fix build with rust 1.47

[packages/thunderbird.git] / rust-1.47.patch

# HG changeset patch
# User Emilio Cobos Álvarez <emilio@crisal.io>
# Date 1599584448 0
# Node ID 85c38ea4d34969797eb5d24265cd90cc6841e6ae
# Parent  5aa243a2fe9d77578dd95ce3ab3a2aa6c1e92604
Bug 1663715 - Update syn and proc-macro2 so that Firefox can build on Rust nightly again. r=froydnj, a=RyanVM

Generated with:

  cargo update -p syn --precise 1.0.40
  ./mach vendor rust

Rust issue: https://github.com/rust-lang/rust/issues/76482

Differential Revision: https://phabricator.services.mozilla.com/D89473

diff --git a/Cargo.lock b/Cargo.lock
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3712,19 +3712,19 @@ checksum = "ecd45702f76d6d3c75a80564378a
 dependencies = [
  "proc-macro2",
  "quote",
  "syn",
 ]
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "90cf5f418035b98e655e9cdb225047638296b862b42411c4e45bb88d700f7fc0"
+version = "1.0.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "175c513d55719db99da20232b06cda8bab6b83ec2d04e3283edf0213c37c1a29"
 dependencies = [
  "unicode-xid",
 ]
 
 [[package]]
 name = "procedural-masquerade"
 version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -4642,19 +4642,19 @@ dependencies = [
  "cc",
  "gleam",
  "glsl-to-cxx",
  "webrender_build",
 ]
 
 [[package]]
 name = "syn"
-version = "1.0.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "66850e97125af79138385e9b88339cbcd037e3f28ceab8c5ad98e64f0f1f80bf"
+version = "1.0.40"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "963f7d3cc59b59b9325165add223142bbf1df27655d07789f109896d353d8350"
 dependencies = [
  "proc-macro2",
  "quote",
  "unicode-xid",
 ]
 
 [[package]]
 name = "sync-guid"
diff --git a/third_party/rust/proc-macro2/.cargo-checksum.json b/third_party/rust/proc-macro2/.cargo-checksum.json
--- a/third_party/rust/proc-macro2/.cargo-checksum.json
+++ b/third_party/rust/proc-macro2/.cargo-checksum.json
@@ -1,1 +1,1 @@
-{"files":{"Cargo.toml":"e2c1fc6ed317eeef8462fcd192f6b6389e1d84f0d7afeac78f12c23903deddf8","LICENSE-APACHE":"a60eea817514531668d7e00765731449fe14d059d3249e0bc93b36de45f759f2","LICENSE-MIT":"378f5840b258e2779c39418f3f2d7b2ba96f1c7917dd6be0713f88305dbda397","README.md":"362a2156f7645528061b6e8487a2eb0f32f1693012ed82ee57afa05c039bba0d","build.rs":"0cc6e2cb919ddbff59cf1d810283939f97a59f0037540c0f2ee3453237635ff8","src/fallback.rs":"5c6379a90735e27abcc40253b223158c6b1e5784f3850bc423335363e87ef038","src/lib.rs":"ae5251296ad3fcd8b600919a993fec0afd8b56da3e11fef6bc7265b273129936","src/strnom.rs":"37f7791f73f123817ad5403af1d4e2a0714be27401729a2d451bc80b1f26bac9","src/wrapper.rs":"81372e910604217a625aa71c47d43e65f4e008456eae93ac39325c9abf10701a","tests/features.rs":"a86deb8644992a4eb64d9fd493eff16f9cf9c5cb6ade3a634ce0c990cf87d559","tests/marker.rs":"c2652e3ae1dfcb94d2e6313b29712c5dcbd0fe62026913e67bb7cebd7560aade","tests/test.rs":"8c427be9cba1fa8d4a16647e53e3545e5863e29e2c0b311c93c9dd1399abf6a1"},"package":"90cf5f418035b98e655e9cdb225047638296b862b42411c4e45bb88d700f7fc0"}
\ No newline at end of file
+{"files":{"Cargo.toml":"c20c4c52342e65ea11ad8382edc636e628e8f8c5ab7cffddc32426b2fe8fe4cd","LICENSE-APACHE":"a60eea817514531668d7e00765731449fe14d059d3249e0bc93b36de45f759f2","LICENSE-MIT":"378f5840b258e2779c39418f3f2d7b2ba96f1c7917dd6be0713f88305dbda397","README.md":"e1f9d4fc22cff2c049f166a403b41458632a94357890d31cf0e3ad83807fb430","build.rs":"332185d7ad4c859210f5edd7a76bc95146c8277726a2f81417f34927c4424d68","src/detection.rs":"9d25d896889e65330858f2d6f6223c1b98cd1dad189813ad4161ff189fbda2b8","src/fallback.rs":"239f9a25c0f2ab57592288d944c7f1a0f887536b6d4dc2428a17640af8d10a41","src/lib.rs":"2b1d98424c9b23b547dabf85554120e5e65472026a0f3f711b3a097bca7c32fe","src/parse.rs":"500edee9773132e27e44d0fdaa042b1cb9451e29e65124493986f51710c0664c","src/wrapper.rs":"d36c0dced7ec0e7585c1f935cda836080bcae6de1de3d7851d962e9e11a3ac48","tests/comments.rs":"ea6cbe6f4c8852e6a0612893c7d4f2c144a2e6a134a6c3db641a320cbfc3c800","tests/features.rs":"a86deb8644992a4eb64d9fd493eff16f9cf9c5cb6ade3a634ce0c990cf87d559","tests/marker.rs":"c2652e3ae1dfcb94d2e6313b29712c5dcbd0fe62026913e67bb7cebd7560aade","tests/test.rs":"310c856e27ff61c9ec7f0a5cd96031aac02971557b1621f5e17b089d58e79bcd","tests/test_fmt.rs":"745dfdc41d09c5308c221395eb43f2041f0a1413d2927a813bc2ad4554438fe2"},"package":"175c513d55719db99da20232b06cda8bab6b83ec2d04e3283edf0213c37c1a29"}
\ No newline at end of file
diff --git a/third_party/rust/proc-macro2/Cargo.toml b/third_party/rust/proc-macro2/Cargo.toml
--- a/third_party/rust/proc-macro2/Cargo.toml
+++ b/third_party/rust/proc-macro2/Cargo.toml
@@ -8,36 +8,35 @@
 # If you believe there's an error in this file please file an
 # issue against the rust-lang/cargo repository. If you're
 # editing this file be aware that the upstream Cargo.toml
 # will likely look very different (and much more reasonable)
 
 [package]
 edition = "2018"
 name = "proc-macro2"
-version = "1.0.5"
-authors = ["Alex Crichton <alex@alexcrichton.com>"]
-description = "A stable implementation of the upcoming new `proc_macro` API. Comes with an\noption, off by default, to also reimplement itself in terms of the upstream\nunstable API.\n"
-homepage = "https://github.com/alexcrichton/proc-macro2"
+version = "1.0.20"
+authors = ["Alex Crichton <alex@alexcrichton.com>", "David Tolnay <dtolnay@gmail.com>"]
+description = "A substitute implementation of the compiler's `proc_macro` API to decouple\ntoken-based libraries from the procedural macro use case.\n"
 documentation = "https://docs.rs/proc-macro2"
 readme = "README.md"
 keywords = ["macros"]
+categories = ["development-tools::procedural-macro-helpers"]
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/alexcrichton/proc-macro2"
 [package.metadata.docs.rs]
 rustc-args = ["--cfg", "procmacro2_semver_exempt"]
 rustdoc-args = ["--cfg", "procmacro2_semver_exempt"]
+targets = ["x86_64-unknown-linux-gnu"]
 
-[lib]
-name = "proc_macro2"
+[package.metadata.playground]
+features = ["span-locations"]
 [dependencies.unicode-xid]
 version = "0.2"
 [dev-dependencies.quote]
 version = "1.0"
 default_features = false
 
 [features]
 default = ["proc-macro"]
 nightly = []
 proc-macro = []
 span-locations = []
-[badges.travis-ci]
-repository = "alexcrichton/proc-macro2"
diff --git a/third_party/rust/proc-macro2/README.md b/third_party/rust/proc-macro2/README.md
--- a/third_party/rust/proc-macro2/README.md
+++ b/third_party/rust/proc-macro2/README.md
@@ -1,11 +1,11 @@
 # proc-macro2
 
-[![Build Status](https://api.travis-ci.com/alexcrichton/proc-macro2.svg?branch=master)](https://travis-ci.com/alexcrichton/proc-macro2)
+[![Build Status](https://img.shields.io/github/workflow/status/alexcrichton/proc-macro2/build%20and%20test)](https://github.com/alexcrichton/proc-macro2/actions)
 [![Latest Version](https://img.shields.io/crates/v/proc-macro2.svg)](https://crates.io/crates/proc-macro2)
 [![Rust Documentation](https://img.shields.io/badge/api-rustdoc-blue.svg)](https://docs.rs/proc-macro2)
 
 A wrapper around the procedural macro API of the compiler's `proc_macro` crate.
 This library serves two purposes:
 
 - **Bring proc-macro-like functionality to other contexts like build.rs and
   main.rs.** Types from `proc_macro` are entirely specific to procedural macros
diff --git a/third_party/rust/proc-macro2/build.rs b/third_party/rust/proc-macro2/build.rs
--- a/third_party/rust/proc-macro2/build.rs
+++ b/third_party/rust/proc-macro2/build.rs
@@ -9,16 +9,20 @@
 // "wrap_proc_macro"
 //     Wrap types from libproc_macro rather than polyfilling the whole API.
 //     Enabled on rustc 1.29+ as long as procmacro2_semver_exempt is not set,
 //     because we can't emulate the unstable API without emulating everything
 //     else. Also enabled unconditionally on nightly, in which case the
 //     procmacro2_semver_exempt surface area is implemented by using the
 //     nightly-only proc_macro API.
 //
+//  "hygiene"
+//    Enable Span::mixed_site() and non-dummy behavior of Span::resolved_at
+//    and Span::located_at. Enabled on Rust 1.45+.
+//
 // "proc_macro_span"
 //     Enable non-dummy behavior of Span::start and Span::end methods which
 //     requires an unstable compiler feature. Enabled when building with
 //     nightly, unless `-Z allow-feature` in RUSTFLAGS disallows unstable
 //     features.
 //
 // "super_unstable"
 //     Implement the semver exempt API in terms of the nightly-only proc_macro
@@ -52,16 +56,24 @@ fn main() {
         // https://github.com/alexcrichton/proc-macro2/issues/147
         println!("cargo:rustc-cfg=procmacro2_semver_exempt");
     }
 
     if semver_exempt || cfg!(feature = "span-locations") {
         println!("cargo:rustc-cfg=span_locations");
     }
 
+    if version.minor < 39 {
+        println!("cargo:rustc-cfg=no_bind_by_move_pattern_guard");
+    }
+
+    if version.minor >= 45 {
+        println!("cargo:rustc-cfg=hygiene");
+    }
+
     let target = env::var("TARGET").unwrap();
     if !enable_use_proc_macro(&target) {
         return;
     }
 
     println!("cargo:rustc-cfg=use_proc_macro");
 
     if version.nightly || !semver_exempt {
diff --git a/third_party/rust/proc-macro2/src/detection.rs b/third_party/rust/proc-macro2/src/detection.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/proc-macro2/src/detection.rs
@@ -0,0 +1,67 @@
+use std::panic::{self, PanicInfo};
+use std::sync::atomic::*;
+use std::sync::Once;
+
+static WORKS: AtomicUsize = AtomicUsize::new(0);
+static INIT: Once = Once::new();
+
+pub(crate) fn inside_proc_macro() -> bool {
+    match WORKS.load(Ordering::SeqCst) {
+        1 => return false,
+        2 => return true,
+        _ => {}
+    }
+
+    INIT.call_once(initialize);
+    inside_proc_macro()
+}
+
+pub(crate) fn force_fallback() {
+    WORKS.store(1, Ordering::SeqCst);
+}
+
+pub(crate) fn unforce_fallback() {
+    initialize();
+}
+
+// Swap in a null panic hook to avoid printing "thread panicked" to stderr,
+// then use catch_unwind to determine whether the compiler's proc_macro is
+// working. When proc-macro2 is used from outside of a procedural macro all
+// of the proc_macro crate's APIs currently panic.
+//
+// The Once is to prevent the possibility of this ordering:
+//
+//     thread 1 calls take_hook, gets the user's original hook
+//     thread 1 calls set_hook with the null hook
+//     thread 2 calls take_hook, thinks null hook is the original hook
+//     thread 2 calls set_hook with the null hook
+//     thread 1 calls set_hook with the actual original hook
+//     thread 2 calls set_hook with what it thinks is the original hook
+//
+// in which the user's hook has been lost.
+//
+// There is still a race condition where a panic in a different thread can
+// happen during the interval that the user's original panic hook is
+// unregistered such that their hook is incorrectly not called. This is
+// sufficiently unlikely and less bad than printing panic messages to stderr
+// on correct use of this crate. Maybe there is a libstd feature request
+// here. For now, if a user needs to guarantee that this failure mode does
+// not occur, they need to call e.g. `proc_macro2::Span::call_site()` from
+// the main thread before launching any other threads.
+fn initialize() {
+    type PanicHook = dyn Fn(&PanicInfo) + Sync + Send + 'static;
+
+    let null_hook: Box<PanicHook> = Box::new(|_panic_info| { /* ignore */ });
+    let sanity_check = &*null_hook as *const PanicHook;
+    let original_hook = panic::take_hook();
+    panic::set_hook(null_hook);
+
+    let works = panic::catch_unwind(proc_macro::Span::call_site).is_ok();
+    WORKS.store(works as usize + 1, Ordering::SeqCst);
+
+    let hopefully_null_hook = panic::take_hook();
+    panic::set_hook(original_hook);
+    if sanity_check != &*hopefully_null_hook {
+        panic!("observed race condition in proc_macro2::inside_proc_macro");
+    }
+}
diff --git a/third_party/rust/proc-macro2/src/fallback.rs b/third_party/rust/proc-macro2/src/fallback.rs
--- a/third_party/rust/proc-macro2/src/fallback.rs
+++ b/third_party/rust/proc-macro2/src/fallback.rs
@@ -1,41 +1,121 @@
+use crate::parse::{token_stream, Cursor};
+use crate::{Delimiter, Spacing, TokenTree};
 #[cfg(span_locations)]
 use std::cell::RefCell;
 #[cfg(span_locations)]
 use std::cmp;
-use std::fmt;
-use std::iter;
+use std::fmt::{self, Debug, Display};
+use std::iter::FromIterator;
+use std::mem;
 use std::ops::RangeBounds;
 #[cfg(procmacro2_semver_exempt)]
 use std::path::Path;
 use std::path::PathBuf;
 use std::str::FromStr;
 use std::vec;
-
-use crate::strnom::{block_comment, skip_whitespace, whitespace, word_break, Cursor, PResult};
-use crate::{Delimiter, Punct, Spacing, TokenTree};
 use unicode_xid::UnicodeXID;
 
+/// Force use of proc-macro2's fallback implementation of the API for now, even
+/// if the compiler's implementation is available.
+pub fn force() {
+    #[cfg(wrap_proc_macro)]
+    crate::detection::force_fallback();
+}
+
+/// Resume using the compiler's implementation of the proc macro API if it is
+/// available.
+pub fn unforce() {
+    #[cfg(wrap_proc_macro)]
+    crate::detection::unforce_fallback();
+}
+
 #[derive(Clone)]
-pub struct TokenStream {
-    inner: Vec<TokenTree>,
+pub(crate) struct TokenStream {
+    pub(crate) inner: Vec<TokenTree>,
 }
 
 #[derive(Debug)]
-pub struct LexError;
+pub(crate) struct LexError;
 
 impl TokenStream {
     pub fn new() -> TokenStream {
         TokenStream { inner: Vec::new() }
     }
 
     pub fn is_empty(&self) -> bool {
         self.inner.len() == 0
     }
+
+    fn take_inner(&mut self) -> Vec<TokenTree> {
+        mem::replace(&mut self.inner, Vec::new())
+    }
+
+    fn push_token(&mut self, token: TokenTree) {
+        // https://github.com/alexcrichton/proc-macro2/issues/235
+        match token {
+            #[cfg(not(no_bind_by_move_pattern_guard))]
+            TokenTree::Literal(crate::Literal {
+                #[cfg(wrap_proc_macro)]
+                    inner: crate::imp::Literal::Fallback(literal),
+                #[cfg(not(wrap_proc_macro))]
+                    inner: literal,
+                ..
+            }) if literal.text.starts_with('-') => {
+                push_negative_literal(self, literal);
+            }
+            #[cfg(no_bind_by_move_pattern_guard)]
+            TokenTree::Literal(crate::Literal {
+                #[cfg(wrap_proc_macro)]
+                    inner: crate::imp::Literal::Fallback(literal),
+                #[cfg(not(wrap_proc_macro))]
+                    inner: literal,
+                ..
+            }) => {
+                if literal.text.starts_with('-') {
+                    push_negative_literal(self, literal);
+                } else {
+                    self.inner
+                        .push(TokenTree::Literal(crate::Literal::_new_stable(literal)));
+                }
+            }
+            _ => self.inner.push(token),
+        }
+
+        #[cold]
+        fn push_negative_literal(stream: &mut TokenStream, mut literal: Literal) {
+            literal.text.remove(0);
+            let mut punct = crate::Punct::new('-', Spacing::Alone);
+            punct.set_span(crate::Span::_new_stable(literal.span));
+            stream.inner.push(TokenTree::Punct(punct));
+            stream
+                .inner
+                .push(TokenTree::Literal(crate::Literal::_new_stable(literal)));
+        }
+    }
+}
+
+// Nonrecursive to prevent stack overflow.
+impl Drop for TokenStream {
+    fn drop(&mut self) {
+        while let Some(token) = self.inner.pop() {
+            let group = match token {
+                TokenTree::Group(group) => group.inner,
+                _ => continue,
+            };
+            #[cfg(wrap_proc_macro)]
+            let group = match group {
+                crate::imp::Group::Fallback(group) => group,
+                _ => continue,
+            };
+            let mut group = group;
+            self.inner.extend(group.stream.take_inner());
+        }
+    }
 }
 
 #[cfg(span_locations)]
 fn get_cursor(src: &str) -> Cursor {
     // Create a dummy file & add it to the source map
     SOURCE_MAP.with(|cm| {
         let mut cm = cm.borrow_mut();
         let name = format!("<parsed string {}>", cm.files.len());
@@ -54,68 +134,49 @@ fn get_cursor(src: &str) -> Cursor {
 
 impl FromStr for TokenStream {
     type Err = LexError;
 
     fn from_str(src: &str) -> Result<TokenStream, LexError> {
         // Create a dummy file & add it to the source map
         let cursor = get_cursor(src);
 
-        match token_stream(cursor) {
-            Ok((input, output)) => {
-                if skip_whitespace(input).len() != 0 {
-                    Err(LexError)
-                } else {
-                    Ok(output)
-                }
-            }
-            Err(LexError) => Err(LexError),
+        let (rest, tokens) = token_stream(cursor)?;
+        if rest.is_empty() {
+            Ok(tokens)
+        } else {
+            Err(LexError)
         }
     }
 }
 
-impl fmt::Display for TokenStream {
+impl Display for TokenStream {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let mut joint = false;
         for (i, tt) in self.inner.iter().enumerate() {
             if i != 0 && !joint {
                 write!(f, " ")?;
             }
             joint = false;
-            match *tt {
-                TokenTree::Group(ref tt) => {
-                    let (start, end) = match tt.delimiter() {
-                        Delimiter::Parenthesis => ("(", ")"),
-                        Delimiter::Brace => ("{", "}"),
-                        Delimiter::Bracket => ("[", "]"),
-                        Delimiter::None => ("", ""),
-                    };
-                    if tt.stream().into_iter().next().is_none() {
-                        write!(f, "{} {}", start, end)?
-                    } else {
-                        write!(f, "{} {} {}", start, tt.stream(), end)?
-                    }
+            match tt {
+                TokenTree::Group(tt) => Display::fmt(tt, f),
+                TokenTree::Ident(tt) => Display::fmt(tt, f),
+                TokenTree::Punct(tt) => {
+                    joint = tt.spacing() == Spacing::Joint;
+                    Display::fmt(tt, f)
                 }
-                TokenTree::Ident(ref tt) => write!(f, "{}", tt)?,
-                TokenTree::Punct(ref tt) => {
-                    write!(f, "{}", tt.as_char())?;
-                    match tt.spacing() {
-                        Spacing::Alone => {}
-                        Spacing::Joint => joint = true,
-                    }
-                }
-                TokenTree::Literal(ref tt) => write!(f, "{}", tt)?,
-            }
+                TokenTree::Literal(tt) => Display::fmt(tt, f),
+            }?
         }
 
         Ok(())
     }
 }
 
-impl fmt::Debug for TokenStream {
+impl Debug for TokenStream {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.write_str("TokenStream ")?;
         f.debug_list().entries(self.clone()).finish()
     }
 }
 
 #[cfg(use_proc_macro)]
 impl From<proc_macro::TokenStream> for TokenStream {
@@ -134,122 +195,107 @@ impl From<TokenStream> for proc_macro::T
             .to_string()
             .parse()
             .expect("failed to parse to compiler tokens")
     }
 }
 
 impl From<TokenTree> for TokenStream {
     fn from(tree: TokenTree) -> TokenStream {
-        TokenStream { inner: vec![tree] }
+        let mut stream = TokenStream::new();
+        stream.push_token(tree);
+        stream
     }
 }
 
-impl iter::FromIterator<TokenTree> for TokenStream {
-    fn from_iter<I: IntoIterator<Item = TokenTree>>(streams: I) -> Self {
-        let mut v = Vec::new();
-
-        for token in streams.into_iter() {
-            v.push(token);
-        }
-
-        TokenStream { inner: v }
+impl FromIterator<TokenTree> for TokenStream {
+    fn from_iter<I: IntoIterator<Item = TokenTree>>(tokens: I) -> Self {
+        let mut stream = TokenStream::new();
+        stream.extend(tokens);
+        stream
     }
 }
 
-impl iter::FromIterator<TokenStream> for TokenStream {
+impl FromIterator<TokenStream> for TokenStream {
     fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self {
         let mut v = Vec::new();
 
-        for stream in streams.into_iter() {
-            v.extend(stream.inner);
+        for mut stream in streams {
+            v.extend(stream.take_inner());
         }
 
         TokenStream { inner: v }
     }
 }
 
 impl Extend<TokenTree> for TokenStream {
-    fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, streams: I) {
-        self.inner.extend(streams);
+    fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, tokens: I) {
+        tokens.into_iter().for_each(|token| self.push_token(token));
     }
 }
 
 impl Extend<TokenStream> for TokenStream {
     fn extend<I: IntoIterator<Item = TokenStream>>(&mut self, streams: I) {
-        self.inner
-            .extend(streams.into_iter().flat_map(|stream| stream));
+        self.inner.extend(streams.into_iter().flatten());
     }
 }
 
-pub type TokenTreeIter = vec::IntoIter<TokenTree>;
+pub(crate) type TokenTreeIter = vec::IntoIter<TokenTree>;
 
 impl IntoIterator for TokenStream {
     type Item = TokenTree;
     type IntoIter = TokenTreeIter;
 
-    fn into_iter(self) -> TokenTreeIter {
-        self.inner.into_iter()
+    fn into_iter(mut self) -> TokenTreeIter {
+        self.take_inner().into_iter()
     }
 }
 
 #[derive(Clone, PartialEq, Eq)]
-pub struct SourceFile {
+pub(crate) struct SourceFile {
     path: PathBuf,
 }
 
 impl SourceFile {
     /// Get the path to this source file as a string.
     pub fn path(&self) -> PathBuf {
         self.path.clone()
     }
 
     pub fn is_real(&self) -> bool {
         // XXX(nika): Support real files in the future?
         false
     }
 }
 
-impl fmt::Debug for SourceFile {
+impl Debug for SourceFile {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_struct("SourceFile")
             .field("path", &self.path())
             .field("is_real", &self.is_real())
             .finish()
     }
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
-pub struct LineColumn {
+pub(crate) struct LineColumn {
     pub line: usize,
     pub column: usize,
 }
 
 #[cfg(span_locations)]
 thread_local! {
     static SOURCE_MAP: RefCell<SourceMap> = RefCell::new(SourceMap {
         // NOTE: We start with a single dummy file which all call_site() and
         // def_site() spans reference.
-        files: vec![{
+        files: vec![FileInfo {
             #[cfg(procmacro2_semver_exempt)]
-            {
-                FileInfo {
-                    name: "<unspecified>".to_owned(),
-                    span: Span { lo: 0, hi: 0 },
-                    lines: vec![0],
-                }
-            }
-
-            #[cfg(not(procmacro2_semver_exempt))]
-            {
-                FileInfo {
-                    span: Span { lo: 0, hi: 0 },
-                    lines: vec![0],
-                }
-            }
+            name: "<unspecified>".to_owned(),
+            span: Span { lo: 0, hi: 0 },
+            lines: vec![0],
         }],
     });
 }
 
 #[cfg(span_locations)]
 struct FileInfo {
     #[cfg(procmacro2_semver_exempt)]
     name: String,
@@ -277,26 +323,31 @@ impl FileInfo {
         }
     }
 
     fn span_within(&self, span: Span) -> bool {
         span.lo >= self.span.lo && span.hi <= self.span.hi
     }
 }
 
-/// Computesthe offsets of each line in the given source string.
+/// Computes the offsets of each line in the given source string
+/// and the total number of characters
 #[cfg(span_locations)]
-fn lines_offsets(s: &str) -> Vec<usize> {
+fn lines_offsets(s: &str) -> (usize, Vec<usize>) {
     let mut lines = vec![0];
-    let mut prev = 0;
-    while let Some(len) = s[prev..].find('\n') {
-        prev += len + 1;
-        lines.push(prev);
+    let mut total = 0;
+
+    for ch in s.chars() {
+        total += 1;
+        if ch == '\n' {
+            lines.push(total);
+        }
     }
-    lines
+
+    (total, lines)
 }
 
 #[cfg(span_locations)]
 struct SourceMap {
     files: Vec<FileInfo>,
 }
 
 #[cfg(span_locations)]
@@ -305,81 +356,83 @@ impl SourceMap {
         // Add 1 so there's always space between files.
         //
         // We'll always have at least 1 file, as we initialize our files list
         // with a dummy file.
         self.files.last().unwrap().span.hi + 1
     }
 
     fn add_file(&mut self, name: &str, src: &str) -> Span {
-        let lines = lines_offsets(src);
+        let (len, lines) = lines_offsets(src);
         let lo = self.next_start_pos();
         // XXX(nika): Shouild we bother doing a checked cast or checked add here?
         let span = Span {
             lo,
-            hi: lo + (src.len() as u32),
+            hi: lo + (len as u32),
         };
 
-        #[cfg(procmacro2_semver_exempt)]
         self.files.push(FileInfo {
+            #[cfg(procmacro2_semver_exempt)]
             name: name.to_owned(),
             span,
             lines,
         });
 
         #[cfg(not(procmacro2_semver_exempt))]
-        self.files.push(FileInfo { span, lines });
         let _ = name;
 
         span
     }
 
     fn fileinfo(&self, span: Span) -> &FileInfo {
         for file in &self.files {
             if file.span_within(span) {
                 return file;
             }
         }
         panic!("Invalid span with no related FileInfo!");
     }
 }
 
 #[derive(Clone, Copy, PartialEq, Eq)]
-pub struct Span {
+pub(crate) struct Span {
     #[cfg(span_locations)]
-    lo: u32,
+    pub(crate) lo: u32,
     #[cfg(span_locations)]
-    hi: u32,
+    pub(crate) hi: u32,
 }
 
 impl Span {
     #[cfg(not(span_locations))]
     pub fn call_site() -> Span {
         Span {}
     }
 
     #[cfg(span_locations)]
     pub fn call_site() -> Span {
         Span { lo: 0, hi: 0 }
     }
 
+    #[cfg(hygiene)]
+    pub fn mixed_site() -> Span {
+        Span::call_site()
+    }
+
     #[cfg(procmacro2_semver_exempt)]
     pub fn def_site() -> Span {
         Span::call_site()
     }
 
-    #[cfg(procmacro2_semver_exempt)]
     pub fn resolved_at(&self, _other: Span) -> Span {
         // Stable spans consist only of line/column information, so
         // `resolved_at` and `located_at` only select which span the
         // caller wants line/column information from.
         *self
     }
 
-    #[cfg(procmacro2_semver_exempt)]
     pub fn located_at(&self, other: Span) -> Span {
         other
     }
 
     #[cfg(procmacro2_semver_exempt)]
     pub fn source_file(&self) -> SourceFile {
         SOURCE_MAP.with(|cm| {
             let cm = cm.borrow();
@@ -422,36 +475,69 @@ impl Span {
                 return None;
             }
             Some(Span {
                 lo: cmp::min(self.lo, other.lo),
                 hi: cmp::max(self.hi, other.hi),
             })
         })
     }
+
+    #[cfg(not(span_locations))]
+    fn first_byte(self) -> Self {
+        self
+    }
+
+    #[cfg(span_locations)]
+    fn first_byte(self) -> Self {
+        Span {
+            lo: self.lo,
+            hi: cmp::min(self.lo.saturating_add(1), self.hi),
+        }
+    }
+
+    #[cfg(not(span_locations))]
+    fn last_byte(self) -> Self {
+        self
+    }
+
+    #[cfg(span_locations)]
+    fn last_byte(self) -> Self {
+        Span {
+            lo: cmp::max(self.hi.saturating_sub(1), self.lo),
+            hi: self.hi,
+        }
+    }
 }
 
-impl fmt::Debug for Span {
+impl Debug for Span {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        #[cfg(procmacro2_semver_exempt)]
+        #[cfg(span_locations)]
         return write!(f, "bytes({}..{})", self.lo, self.hi);
 
-        #[cfg(not(procmacro2_semver_exempt))]
+        #[cfg(not(span_locations))]
         write!(f, "Span")
     }
 }
 
-pub fn debug_span_field_if_nontrivial(debug: &mut fmt::DebugStruct, span: Span) {
-    if cfg!(procmacro2_semver_exempt) {
+pub(crate) fn debug_span_field_if_nontrivial(debug: &mut fmt::DebugStruct, span: Span) {
+    #[cfg(span_locations)]
+    {
+        if span.lo == 0 && span.hi == 0 {
+            return;
+        }
+    }
+
+    if cfg!(span_locations) {
         debug.field("span", &span);
     }
 }
 
 #[derive(Clone)]
-pub struct Group {
+pub(crate) struct Group {
     delimiter: Delimiter,
     stream: TokenStream,
     span: Span,
 }
 
 impl Group {
     pub fn new(delimiter: Delimiter, stream: TokenStream) -> Group {
         Group {
@@ -469,58 +555,67 @@ impl Group {
         self.stream.clone()
     }
 
     pub fn span(&self) -> Span {
         self.span
     }
 
     pub fn span_open(&self) -> Span {
-        self.span
+        self.span.first_byte()
     }
 
     pub fn span_close(&self) -> Span {
-        self.span
+        self.span.last_byte()
     }
 
     pub fn set_span(&mut self, span: Span) {
         self.span = span;
     }
 }
 
-impl fmt::Display for Group {
+impl Display for Group {
+    // We attempt to match libproc_macro's formatting.
+    // Empty parens: ()
+    // Nonempty parens: (...)
+    // Empty brackets: []
+    // Nonempty brackets: [...]
+    // Empty braces: { }
+    // Nonempty braces: { ... }
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let (left, right) = match self.delimiter {
+        let (open, close) = match self.delimiter {
             Delimiter::Parenthesis => ("(", ")"),
-            Delimiter::Brace => ("{", "}"),
+            Delimiter::Brace => ("{ ", "}"),
             Delimiter::Bracket => ("[", "]"),
             Delimiter::None => ("", ""),
         };
 
-        f.write_str(left)?;
-        self.stream.fmt(f)?;
-        f.write_str(right)?;
+        f.write_str(open)?;
+        Display::fmt(&self.stream, f)?;
+        if self.delimiter == Delimiter::Brace && !self.stream.inner.is_empty() {
+            f.write_str(" ")?;
+        }
+        f.write_str(close)?;
 
         Ok(())
     }
 }
 
-impl fmt::Debug for Group {
+impl Debug for Group {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         let mut debug = fmt.debug_struct("Group");
         debug.field("delimiter", &self.delimiter);
         debug.field("stream", &self.stream);
-        #[cfg(procmacro2_semver_exempt)]
-        debug.field("span", &self.span);
+        debug_span_field_if_nontrivial(&mut debug, self.span);
         debug.finish()
     }
 }
 
 #[derive(Clone)]
-pub struct Ident {
+pub(crate) struct Ident {
     sym: String,
     span: Span,
     raw: bool,
 }
 
 impl Ident {
     fn _new(string: &str, raw: bool, span: Span) -> Ident {
         validate_ident(string);
@@ -544,26 +639,24 @@ impl Ident {
         self.span
     }
 
     pub fn set_span(&mut self, span: Span) {
         self.span = span;
     }
 }
 
-#[inline]
-fn is_ident_start(c: char) -> bool {
+pub(crate) fn is_ident_start(c: char) -> bool {
     ('a' <= c && c <= 'z')
         || ('A' <= c && c <= 'Z')
         || c == '_'
         || (c > '\x7f' && UnicodeXID::is_xid_start(c))
 }
 
-#[inline]
-fn is_ident_continue(c: char) -> bool {
+pub(crate) fn is_ident_continue(c: char) -> bool {
     ('a' <= c && c <= 'z')
         || ('A' <= c && c <= 'Z')
         || c == '_'
         || ('0' <= c && c <= '9')
         || (c > '\x7f' && UnicodeXID::is_xid_continue(c))
 }
 
 fn validate_ident(string: &str) {
@@ -610,49 +703,49 @@ where
         if self.raw {
             other.starts_with("r#") && self.sym == other[2..]
         } else {
             self.sym == other
         }
     }
 }
 
-impl fmt::Display for Ident {
+impl Display for Ident {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         if self.raw {
-            "r#".fmt(f)?;
+            f.write_str("r#")?;
         }
-        self.sym.fmt(f)
+        Display::fmt(&self.sym, f)
     }
 }
 
-impl fmt::Debug for Ident {
+impl Debug for Ident {
     // Ident(proc_macro), Ident(r#union)
-    #[cfg(not(procmacro2_semver_exempt))]
+    #[cfg(not(span_locations))]
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let mut debug = f.debug_tuple("Ident");
         debug.field(&format_args!("{}", self));
         debug.finish()
     }
 
     // Ident {
     //     sym: proc_macro,
     //     span: bytes(128..138)
     // }
-    #[cfg(procmacro2_semver_exempt)]
+    #[cfg(span_locations)]
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let mut debug = f.debug_struct("Ident");
         debug.field("sym", &format_args!("{}", self));
-        debug.field("span", &self.span);
+        debug_span_field_if_nontrivial(&mut debug, self.span);
         debug.finish()
     }
 }
 
 #[derive(Clone)]
-pub struct Literal {
+pub(crate) struct Literal {
     text: String,
     span: Span,
 }
 
 macro_rules! suffixed_numbers {
     ($($name:ident => $kind:ident,)*) => ($(
         pub fn $name(n: $kind) -> Literal {
             Literal::_new(format!(concat!("{}", stringify!($kind)), n))
@@ -664,17 +757,17 @@ macro_rules! unsuffixed_numbers {
     ($($name:ident => $kind:ident,)*) => ($(
         pub fn $name(n: $kind) -> Literal {
             Literal::_new(n.to_string())
         }
     )*)
 }
 
 impl Literal {
-    fn _new(text: String) -> Literal {
+    pub(crate) fn _new(text: String) -> Literal {
         Literal {
             text,
             span: Span::call_site(),
         }
     }
 
     suffixed_numbers! {
         u8_suffixed => u8,
@@ -706,61 +799,62 @@ impl Literal {
         i32_unsuffixed => i32,
         i64_unsuffixed => i64,
         i128_unsuffixed => i128,
         isize_unsuffixed => isize,
     }
 
     pub fn f32_unsuffixed(f: f32) -> Literal {
         let mut s = f.to_string();
-        if !s.contains(".") {
+        if !s.contains('.') {
             s.push_str(".0");
         }
         Literal::_new(s)
     }
 
     pub fn f64_unsuffixed(f: f64) -> Literal {
         let mut s = f.to_string();
-        if !s.contains(".") {
+        if !s.contains('.') {
             s.push_str(".0");
         }
         Literal::_new(s)
     }
 
     pub fn string(t: &str) -> Literal {
         let mut text = String::with_capacity(t.len() + 2);
         text.push('"');
         for c in t.chars() {
             if c == '\'' {
-                // escape_default turns this into "\'" which is unnecessary.
+                // escape_debug turns this into "\'" which is unnecessary.
                 text.push(c);
             } else {
-                text.extend(c.escape_default());
+                text.extend(c.escape_debug());
             }
         }
         text.push('"');
         Literal::_new(text)
     }
 
     pub fn character(t: char) -> Literal {
         let mut text = String::new();
         text.push('\'');
         if t == '"' {
-            // escape_default turns this into '\"' which is unnecessary.
+            // escape_debug turns this into '\"' which is unnecessary.
             text.push(t);
         } else {
-            text.extend(t.escape_default());
+            text.extend(t.escape_debug());
         }
         text.push('\'');
         Literal::_new(text)
     }
 
     pub fn byte_string(bytes: &[u8]) -> Literal {
         let mut escaped = "b\"".to_string();
         for b in bytes {
+            #[allow(clippy::match_overlapping_arm)]
             match *b {
                 b'\0' => escaped.push_str(r"\0"),
                 b'\t' => escaped.push_str(r"\t"),
                 b'\n' => escaped.push_str(r"\n"),
                 b'\r' => escaped.push_str(r"\r"),
                 b'"' => escaped.push_str("\\\""),
                 b'\\' => escaped.push_str("\\\\"),
                 b'\x20'..=b'\x7E' => escaped.push(*b as char),
@@ -779,656 +873,22 @@ impl Literal {
         self.span = span;
     }
 
     pub fn subspan<R: RangeBounds<usize>>(&self, _range: R) -> Option<Span> {
         None
     }
 }
 
-impl fmt::Display for Literal {
+impl Display for Literal {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.text.fmt(f)
-    }
-}
-
-impl fmt::Debug for Literal {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        let mut debug = fmt.debug_struct("Literal");
-        debug.field("lit", &format_args!("{}", self.text));
-        #[cfg(procmacro2_semver_exempt)]
-        debug.field("span", &self.span);
-        debug.finish()
-    }
-}
-
-fn token_stream(mut input: Cursor) -> PResult<TokenStream> {
-    let mut trees = Vec::new();
-    loop {
-        let input_no_ws = skip_whitespace(input);
-        if input_no_ws.rest.len() == 0 {
-            break;
-        }
-        if let Ok((a, tokens)) = doc_comment(input_no_ws) {
-            input = a;
-            trees.extend(tokens);
-            continue;
-        }
-
-        let (a, tt) = match token_tree(input_no_ws) {
-            Ok(p) => p,
-            Err(_) => break,
-        };
-        trees.push(tt);
-        input = a;
-    }
-    Ok((input, TokenStream { inner: trees }))
-}
-
-#[cfg(not(span_locations))]
-fn spanned<'a, T>(
-    input: Cursor<'a>,
-    f: fn(Cursor<'a>) -> PResult<'a, T>,
-) -> PResult<'a, (T, crate::Span)> {
-    let (a, b) = f(skip_whitespace(input))?;
-    Ok((a, ((b, crate::Span::_new_stable(Span::call_site())))))
-}
-
-#[cfg(span_locations)]
-fn spanned<'a, T>(
-    input: Cursor<'a>,
-    f: fn(Cursor<'a>) -> PResult<'a, T>,
-) -> PResult<'a, (T, crate::Span)> {
-    let input = skip_whitespace(input);
-    let lo = input.off;
-    let (a, b) = f(input)?;
-    let hi = a.off;
-    let span = crate::Span::_new_stable(Span { lo, hi });
-    Ok((a, (b, span)))
-}
-
-fn token_tree(input: Cursor) -> PResult<TokenTree> {
-    let (rest, (mut tt, span)) = spanned(input, token_kind)?;
-    tt.set_span(span);
-    Ok((rest, tt))
-}
-
-named!(token_kind -> TokenTree, alt!(
-    map!(group, |g| TokenTree::Group(crate::Group::_new_stable(g)))
-    |
-    map!(literal, |l| TokenTree::Literal(crate::Literal::_new_stable(l))) // must be before symbol
-    |
-    map!(op, TokenTree::Punct)
-    |
-    symbol_leading_ws
-));
-
-named!(group -> Group, alt!(
-    delimited!(
-        punct!("("),
-        token_stream,
-        punct!(")")
-    ) => { |ts| Group::new(Delimiter::Parenthesis, ts) }
-    |
-    delimited!(
-        punct!("["),
-        token_stream,
-        punct!("]")
-    ) => { |ts| Group::new(Delimiter::Bracket, ts) }
-    |
-    delimited!(
-        punct!("{"),
-        token_stream,
-        punct!("}")
-    ) => { |ts| Group::new(Delimiter::Brace, ts) }
-));
-
-fn symbol_leading_ws(input: Cursor) -> PResult<TokenTree> {
-    symbol(skip_whitespace(input))
-}
-
-fn symbol(input: Cursor) -> PResult<TokenTree> {
-    let raw = input.starts_with("r#");
-    let rest = input.advance((raw as usize) << 1);
-
-    let (rest, sym) = symbol_not_raw(rest)?;
-
-    if !raw {
-        let ident = crate::Ident::new(sym, crate::Span::call_site());
-        return Ok((rest, ident.into()));
-    }
-
-    if sym == "_" {
-        return Err(LexError);
-    }
-
-    let ident = crate::Ident::_new_raw(sym, crate::Span::call_site());
-    Ok((rest, ident.into()))
-}
-
-fn symbol_not_raw(input: Cursor) -> PResult<&str> {
-    let mut chars = input.char_indices();
-
-    match chars.next() {
-        Some((_, ch)) if is_ident_start(ch) => {}
-        _ => return Err(LexError),
-    }
-
-    let mut end = input.len();
-    for (i, ch) in chars {
-        if !is_ident_continue(ch) {
-            end = i;
-            break;
-        }
-    }
-
-    Ok((input.advance(end), &input.rest[..end]))
-}
-
-fn literal(input: Cursor) -> PResult<Literal> {
-    let input_no_ws = skip_whitespace(input);
-
-    match literal_nocapture(input_no_ws) {
-        Ok((a, ())) => {
-            let start = input.len() - input_no_ws.len();
-            let len = input_no_ws.len() - a.len();
-            let end = start + len;
-            Ok((a, Literal::_new(input.rest[start..end].to_string())))
-        }
-        Err(LexError) => Err(LexError),
+        Display::fmt(&self.text, f)
     }
 }
 
-named!(literal_nocapture -> (), alt!(
-    string
-    |
-    byte_string
-    |
-    byte
-    |
-    character
-    |
-    float
-    |
-    int
-));
-
-named!(string -> (), alt!(
-    quoted_string
-    |
-    preceded!(
-        punct!("r"),
-        raw_string
-    ) => { |_| () }
-));
-
-named!(quoted_string -> (), do_parse!(
-    punct!("\"") >>
-    cooked_string >>
-    tag!("\"") >>
-    option!(symbol_not_raw) >>
-    (())
-));
-
-fn cooked_string(input: Cursor) -> PResult<()> {
-    let mut chars = input.char_indices().peekable();
-    while let Some((byte_offset, ch)) = chars.next() {
-        match ch {
-            '"' => {
-                return Ok((input.advance(byte_offset), ()));
-            }
-            '\r' => {
-                if let Some((_, '\n')) = chars.next() {
-                    // ...
-                } else {
-                    break;
-                }
-            }
-            '\\' => match chars.next() {
-                Some((_, 'x')) => {
-                    if !backslash_x_char(&mut chars) {
-                        break;
-                    }
-                }
-                Some((_, 'n')) | Some((_, 'r')) | Some((_, 't')) | Some((_, '\\'))
-                | Some((_, '\'')) | Some((_, '"')) | Some((_, '0')) => {}
-                Some((_, 'u')) => {
-                    if !backslash_u(&mut chars) {
-                        break;
-                    }
-                }
-                Some((_, '\n')) | Some((_, '\r')) => {
-                    while let Some(&(_, ch)) = chars.peek() {
-                        if ch.is_whitespace() {
-                            chars.next();
-                        } else {
-                            break;
-                        }
-                    }
-                }
-                _ => break,
-            },
-            _ch => {}
-        }
-    }
-    Err(LexError)
-}
-
-named!(byte_string -> (), alt!(
-    delimited!(
-        punct!("b\""),
-        cooked_byte_string,
-        tag!("\"")
-    ) => { |_| () }
-    |
-    preceded!(
-        punct!("br"),
-        raw_string
-    ) => { |_| () }
-));
-
-fn cooked_byte_string(mut input: Cursor) -> PResult<()> {
-    let mut bytes = input.bytes().enumerate();
-    'outer: while let Some((offset, b)) = bytes.next() {
-        match b {
-            b'"' => {
-                return Ok((input.advance(offset), ()));
-            }
-            b'\r' => {
-                if let Some((_, b'\n')) = bytes.next() {
-                    // ...
-                } else {
-                    break;
-                }
-            }
-            b'\\' => match bytes.next() {
-                Some((_, b'x')) => {
-                    if !backslash_x_byte(&mut bytes) {
-                        break;
-                    }
-                }
-                Some((_, b'n')) | Some((_, b'r')) | Some((_, b't')) | Some((_, b'\\'))
-                | Some((_, b'0')) | Some((_, b'\'')) | Some((_, b'"')) => {}
-                Some((newline, b'\n')) | Some((newline, b'\r')) => {
-                    let rest = input.advance(newline + 1);
-                    for (offset, ch) in rest.char_indices() {
-                        if !ch.is_whitespace() {
-                            input = rest.advance(offset);
-                            bytes = input.bytes().enumerate();
-                            continue 'outer;
-                        }
-                    }
-                    break;
-                }
-                _ => break,
-            },
-            b if b < 0x80 => {}
-            _ => break,
-        }
-    }
-    Err(LexError)
-}
-
-fn raw_string(input: Cursor) -> PResult<()> {
-    let mut chars = input.char_indices();
-    let mut n = 0;
-    while let Some((byte_offset, ch)) = chars.next() {
-        match ch {
-            '"' => {
-                n = byte_offset;
-                break;
-            }
-            '#' => {}
-            _ => return Err(LexError),
-        }
-    }
-    for (byte_offset, ch) in chars {
-        match ch {
-            '"' if input.advance(byte_offset + 1).starts_with(&input.rest[..n]) => {
-                let rest = input.advance(byte_offset + 1 + n);
-                return Ok((rest, ()));
-            }
-            '\r' => {}
-            _ => {}
-        }
-    }
-    Err(LexError)
-}
-
-named!(byte -> (), do_parse!(
-    punct!("b") >>
-    tag!("'") >>
-    cooked_byte >>
-    tag!("'") >>
-    (())
-));
-
-fn cooked_byte(input: Cursor) -> PResult<()> {
-    let mut bytes = input.bytes().enumerate();
-    let ok = match bytes.next().map(|(_, b)| b) {
-        Some(b'\\') => match bytes.next().map(|(_, b)| b) {
-            Some(b'x') => backslash_x_byte(&mut bytes),
-            Some(b'n') | Some(b'r') | Some(b't') | Some(b'\\') | Some(b'0') | Some(b'\'')
-            | Some(b'"') => true,
-            _ => false,
-        },
-        b => b.is_some(),
-    };
-    if ok {
-        match bytes.next() {
-            Some((offset, _)) => {
-                if input.chars().as_str().is_char_boundary(offset) {
-                    Ok((input.advance(offset), ()))
-                } else {
-                    Err(LexError)
-                }
-            }
-            None => Ok((input.advance(input.len()), ())),
-        }
-    } else {
-        Err(LexError)
-    }
-}
-
-named!(character -> (), do_parse!(
-    punct!("'") >>
-    cooked_char >>
-    tag!("'") >>
-    (())
-));
-
-fn cooked_char(input: Cursor) -> PResult<()> {
-    let mut chars = input.char_indices();
-    let ok = match chars.next().map(|(_, ch)| ch) {
-        Some('\\') => match chars.next().map(|(_, ch)| ch) {
-            Some('x') => backslash_x_char(&mut chars),
-            Some('u') => backslash_u(&mut chars),
-            Some('n') | Some('r') | Some('t') | Some('\\') | Some('0') | Some('\'') | Some('"') => {
-                true
-            }
-            _ => false,
-        },
-        ch => ch.is_some(),
-    };
-    if ok {
-        match chars.next() {
-            Some((idx, _)) => Ok((input.advance(idx), ())),
-            None => Ok((input.advance(input.len()), ())),
-        }
-    } else {
-        Err(LexError)
+impl Debug for Literal {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let mut debug = fmt.debug_struct("Literal");
+        debug.field("lit", &format_args!("{}", self.text));
+        debug_span_field_if_nontrivial(&mut debug, self.span);
+        debug.finish()
     }
 }
-
-macro_rules! next_ch {
-    ($chars:ident @ $pat:pat $(| $rest:pat)*) => {
-        match $chars.next() {
-            Some((_, ch)) => match ch {
-                $pat $(| $rest)*  => ch,
-                _ => return false,
-            },
-            None => return false
-        }
-    };
-}
-
-fn backslash_x_char<I>(chars: &mut I) -> bool
-where
-    I: Iterator<Item = (usize, char)>,
-{
-    next_ch!(chars @ '0'..='7');
-    next_ch!(chars @ '0'..='9' | 'a'..='f' | 'A'..='F');
-    true
-}
-
-fn backslash_x_byte<I>(chars: &mut I) -> bool
-where
-    I: Iterator<Item = (usize, u8)>,
-{
-    next_ch!(chars @ b'0'..=b'9' | b'a'..=b'f' | b'A'..=b'F');
-    next_ch!(chars @ b'0'..=b'9' | b'a'..=b'f' | b'A'..=b'F');
-    true
-}
-
-fn backslash_u<I>(chars: &mut I) -> bool
-where
-    I: Iterator<Item = (usize, char)>,
-{
-    next_ch!(chars @ '{');
-    next_ch!(chars @ '0'..='9' | 'a'..='f' | 'A'..='F');
-    loop {
-        let c = next_ch!(chars @ '0'..='9' | 'a'..='f' | 'A'..='F' | '_' | '}');
-        if c == '}' {
-            return true;
-        }
-    }
-}
-
-fn float(input: Cursor) -> PResult<()> {
-    let (mut rest, ()) = float_digits(input)?;
-    if let Some(ch) = rest.chars().next() {
-        if is_ident_start(ch) {
-            rest = symbol_not_raw(rest)?.0;
-        }
-    }
-    word_break(rest)
-}
-
-fn float_digits(input: Cursor) -> PResult<()> {
-    let mut chars = input.chars().peekable();
-    match chars.next() {
-        Some(ch) if ch >= '0' && ch <= '9' => {}
-        _ => return Err(LexError),
-    }
-
-    let mut len = 1;
-    let mut has_dot = false;
-    let mut has_exp = false;
-    while let Some(&ch) = chars.peek() {
-        match ch {
-            '0'..='9' | '_' => {
-                chars.next();
-                len += 1;
-            }
-            '.' => {
-                if has_dot {
-                    break;
-                }
-                chars.next();
-                if chars
-                    .peek()
-                    .map(|&ch| ch == '.' || is_ident_start(ch))
-                    .unwrap_or(false)
-                {
-                    return Err(LexError);
-                }
-                len += 1;
-                has_dot = true;
-            }
-            'e' | 'E' => {
-                chars.next();
-                len += 1;
-                has_exp = true;
-                break;
-            }
-            _ => break,
-        }
-    }
-
-    let rest = input.advance(len);
-    if !(has_dot || has_exp || rest.starts_with("f32") || rest.starts_with("f64")) {
-        return Err(LexError);
-    }
-
-    if has_exp {
-        let mut has_exp_value = false;
-        while let Some(&ch) = chars.peek() {
-            match ch {
-                '+' | '-' => {
-                    if has_exp_value {
-                        break;
-                    }
-                    chars.next();
-                    len += 1;
-                }
-                '0'..='9' => {
-                    chars.next();
-                    len += 1;
-                    has_exp_value = true;
-                }
-                '_' => {
-                    chars.next();
-                    len += 1;
-                }
-                _ => break,
-            }
-        }
-        if !has_exp_value {
-            return Err(LexError);
-        }
-    }
-
-    Ok((input.advance(len), ()))
-}
-
-fn int(input: Cursor) -> PResult<()> {
-    let (mut rest, ()) = digits(input)?;
-    if let Some(ch) = rest.chars().next() {
-        if is_ident_start(ch) {
-            rest = symbol_not_raw(rest)?.0;
-        }
-    }
-    word_break(rest)
-}
-
-fn digits(mut input: Cursor) -> PResult<()> {
-    let base = if input.starts_with("0x") {
-        input = input.advance(2);
-        16
-    } else if input.starts_with("0o") {
-        input = input.advance(2);
-        8
-    } else if input.starts_with("0b") {
-        input = input.advance(2);
-        2
-    } else {
-        10
-    };
-
-    let mut len = 0;
-    let mut empty = true;
-    for b in input.bytes() {
-        let digit = match b {
-            b'0'..=b'9' => (b - b'0') as u64,
-            b'a'..=b'f' => 10 + (b - b'a') as u64,
-            b'A'..=b'F' => 10 + (b - b'A') as u64,
-            b'_' => {
-                if empty && base == 10 {
-                    return Err(LexError);
-                }
-                len += 1;
-                continue;
-            }
-            _ => break,
-        };
-        if digit >= base {
-            return Err(LexError);
-        }
-        len += 1;
-        empty = false;
-    }
-    if empty {
-        Err(LexError)
-    } else {
-        Ok((input.advance(len), ()))
-    }
-}
-
-fn op(input: Cursor) -> PResult<Punct> {
-    let input = skip_whitespace(input);
-    match op_char(input) {
-        Ok((rest, '\'')) => {
-            symbol(rest)?;
-            Ok((rest, Punct::new('\'', Spacing::Joint)))
-        }
-        Ok((rest, ch)) => {
-            let kind = match op_char(rest) {
-                Ok(_) => Spacing::Joint,
-                Err(LexError) => Spacing::Alone,
-            };
-            Ok((rest, Punct::new(ch, kind)))
-        }
-        Err(LexError) => Err(LexError),
-    }
-}
-
-fn op_char(input: Cursor) -> PResult<char> {
-    if input.starts_with("//") || input.starts_with("/*") {
-        // Do not accept `/` of a comment as an op.
-        return Err(LexError);
-    }
-
-    let mut chars = input.chars();
-    let first = match chars.next() {
-        Some(ch) => ch,
-        None => {
-            return Err(LexError);
-        }
-    };
-    let recognized = "~!@#$%^&*-=+|;:,<.>/?'";
-    if recognized.contains(first) {
-        Ok((input.advance(first.len_utf8()), first))
-    } else {
-        Err(LexError)
-    }
-}
-
-fn doc_comment(input: Cursor) -> PResult<Vec<TokenTree>> {
-    let mut trees = Vec::new();
-    let (rest, ((comment, inner), span)) = spanned(input, doc_comment_contents)?;
-    trees.push(TokenTree::Punct(Punct::new('#', Spacing::Alone)));
-    if inner {
-        trees.push(Punct::new('!', Spacing::Alone).into());
-    }
-    let mut stream = vec![
-        TokenTree::Ident(crate::Ident::new("doc", span)),
-        TokenTree::Punct(Punct::new('=', Spacing::Alone)),
-        TokenTree::Literal(crate::Literal::string(comment)),
-    ];
-    for tt in stream.iter_mut() {
-        tt.set_span(span);
-    }
-    let group = Group::new(Delimiter::Bracket, stream.into_iter().collect());
-    trees.push(crate::Group::_new_stable(group).into());
-    for tt in trees.iter_mut() {
-        tt.set_span(span);
-    }
-    Ok((rest, trees))
-}
-
-named!(doc_comment_contents -> (&str, bool), alt!(
-    do_parse!(
-        punct!("//!") >>
-        s: take_until_newline_or_eof!() >>
-        ((s, true))
-    )
-    |
-    do_parse!(
-        option!(whitespace) >>
-        peek!(tag!("/*!")) >>
-        s: block_comment >>
-        ((s, true))
-    )
-    |
-    do_parse!(
-        punct!("///") >>
-        not!(tag!("/")) >>
-        s: take_until_newline_or_eof!() >>
-        ((s, false))
-    )
-    |
-    do_parse!(
-        option!(whitespace) >>
-        peek!(tuple!(tag!("/**"), not!(tag!("*")))) >>
-        s: block_comment >>
-        ((s, false))
-    )
-));
diff --git a/third_party/rust/proc-macro2/src/lib.rs b/third_party/rust/proc-macro2/src/lib.rs
--- a/third_party/rust/proc-macro2/src/lib.rs
+++ b/third_party/rust/proc-macro2/src/lib.rs
@@ -73,37 +73,44 @@
 //!
 //! # Thread-Safety
 //!
 //! Most types in this crate are `!Sync` because the underlying compiler
 //! types make use of thread-local memory, meaning they cannot be accessed from
 //! a different thread.
 
 // Proc-macro2 types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/proc-macro2/1.0.5")]
+#![doc(html_root_url = "https://docs.rs/proc-macro2/1.0.20")]
 #![cfg_attr(any(proc_macro_span, super_unstable), feature(proc_macro_span))]
 #![cfg_attr(super_unstable, feature(proc_macro_raw_ident, proc_macro_def_site))]
+#![allow(clippy::needless_doctest_main)]
 
 #[cfg(use_proc_macro)]
 extern crate proc_macro;
 
 use std::cmp::Ordering;
-use std::fmt;
+use std::fmt::{self, Debug, Display};
 use std::hash::{Hash, Hasher};
 use std::iter::FromIterator;
 use std::marker;
 use std::ops::RangeBounds;
 #[cfg(procmacro2_semver_exempt)]
 use std::path::PathBuf;
 use std::rc::Rc;
 use std::str::FromStr;
 
-#[macro_use]
-mod strnom;
-mod fallback;
+mod parse;
+
+#[cfg(wrap_proc_macro)]
+mod detection;
+
+// Public for proc_macro2::fallback::force() and unforce(), but those are quite
+// a niche use case so we omit it from rustdoc.
+#[doc(hidden)]
+pub mod fallback;
 
 #[cfg(not(wrap_proc_macro))]
 use crate::fallback as imp;
 #[path = "wrapper.rs"]
 #[cfg(wrap_proc_macro)]
 mod imp;
 
 /// An abstract stream of tokens, or more concretely a sequence of token trees.
@@ -223,32 +230,32 @@ impl FromIterator<TokenStream> for Token
         TokenStream::_new(streams.into_iter().map(|i| i.inner).collect())
     }
 }
 
 /// Prints the token stream as a string that is supposed to be losslessly
 /// convertible back into the same token stream (modulo spans), except for
 /// possibly `TokenTree::Group`s with `Delimiter::None` delimiters and negative
 /// numeric literals.
-impl fmt::Display for TokenStream {
+impl Display for TokenStream {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.inner.fmt(f)
+        Display::fmt(&self.inner, f)
     }
 }
 
 /// Prints token in a form convenient for debugging.
-impl fmt::Debug for TokenStream {
+impl Debug for TokenStream {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.inner.fmt(f)
+        Debug::fmt(&self.inner, f)
     }
 }
 
-impl fmt::Debug for LexError {
+impl Debug for LexError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.inner.fmt(f)
+        Debug::fmt(&self.inner, f)
     }
 }
 
 /// The source file of a given `Span`.
 ///
 /// This type is semver exempt and not exposed by default.
 #[cfg(procmacro2_semver_exempt)]
 #[derive(Clone, PartialEq, Eq)]
@@ -286,19 +293,19 @@ impl SourceFile {
     /// Returns `true` if this source file is a real source file, and not
     /// generated by an external macro's expansion.
     pub fn is_real(&self) -> bool {
         self.inner.is_real()
     }
 }
 
 #[cfg(procmacro2_semver_exempt)]
-impl fmt::Debug for SourceFile {
+impl Debug for SourceFile {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.inner.fmt(f)
+        Debug::fmt(&self.inner, f)
     }
 }
 
 /// A line-column pair representing the start or end of a `Span`.
 ///
 /// This type is semver exempt and not exposed by default.
 #[cfg(span_locations)]
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
@@ -306,16 +313,32 @@ pub struct LineColumn {
     /// The 1-indexed line in the source file on which the span starts or ends
     /// (inclusive).
     pub line: usize,
     /// The 0-indexed column (in UTF-8 characters) in the source file on which
     /// the span starts or ends (inclusive).
     pub column: usize,
 }
 
+#[cfg(span_locations)]
+impl Ord for LineColumn {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.line
+            .cmp(&other.line)
+            .then(self.column.cmp(&other.column))
+    }
+}
+
+#[cfg(span_locations)]
+impl PartialOrd for LineColumn {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
 /// A region of source code, along with macro expansion information.
 #[derive(Copy, Clone)]
 pub struct Span {
     inner: imp::Span,
     _marker: marker::PhantomData<Rc<()>>,
 }
 
 impl Span {
@@ -337,38 +360,42 @@ impl Span {
     ///
     /// Identifiers created with this span will be resolved as if they were
     /// written directly at the macro call location (call-site hygiene) and
     /// other code at the macro call site will be able to refer to them as well.
     pub fn call_site() -> Span {
         Span::_new(imp::Span::call_site())
     }
 
+    /// The span located at the invocation of the procedural macro, but with
+    /// local variables, labels, and `$crate` resolved at the definition site
+    /// of the macro. This is the same hygiene behavior as `macro_rules`.
+    ///
+    /// This function requires Rust 1.45 or later.
+    #[cfg(hygiene)]
+    pub fn mixed_site() -> Span {
+        Span::_new(imp::Span::mixed_site())
+    }
+
     /// A span that resolves at the macro definition site.
     ///
     /// This method is semver exempt and not exposed by default.
     #[cfg(procmacro2_semver_exempt)]
     pub fn def_site() -> Span {
         Span::_new(imp::Span::def_site())
     }
 
     /// Creates a new span with the same line/column information as `self` but
     /// that resolves symbols as though it were at `other`.
-    ///
-    /// This method is semver exempt and not exposed by default.
-    #[cfg(procmacro2_semver_exempt)]
     pub fn resolved_at(&self, other: Span) -> Span {
         Span::_new(self.inner.resolved_at(other.inner))
     }
 
     /// Creates a new span with the same name resolution behavior as `self` but
     /// with the line/column information of `other`.
-    ///
-    /// This method is semver exempt and not exposed by default.
-    #[cfg(procmacro2_semver_exempt)]
     pub fn located_at(&self, other: Span) -> Span {
         Span::_new(self.inner.located_at(other.inner))
     }
 
     /// Convert `proc_macro2::Span` to `proc_macro::Span`.
     ///
     /// This method is available when building with a nightly compiler, or when
     /// building with rustc 1.29+ *without* semver exempt features.
@@ -434,19 +461,19 @@ impl Span {
     /// This method is semver exempt and not exposed by default.
     #[cfg(procmacro2_semver_exempt)]
     pub fn eq(&self, other: &Span) -> bool {
         self.inner.eq(&other.inner)
     }
 }
 
 /// Prints a span in a form convenient for debugging.
-impl fmt::Debug for Span {
+impl Debug for Span {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.inner.fmt(f)
+        Debug::fmt(&self.inner, f)
     }
 }
 
 /// A single token or a delimited sequence of token trees (e.g. `[1, (), ..]`).
 #[derive(Clone)]
 pub enum TokenTree {
     /// A token stream surrounded by bracket delimiters.
     Group(Group),
@@ -457,35 +484,35 @@ pub enum TokenTree {
     /// A literal character (`'a'`), string (`"hello"`), number (`2.3`), etc.
     Literal(Literal),
 }
 
 impl TokenTree {
     /// Returns the span of this tree, delegating to the `span` method of
     /// the contained token or a delimited stream.
     pub fn span(&self) -> Span {
-        match *self {
-            TokenTree::Group(ref t) => t.span(),
-            TokenTree::Ident(ref t) => t.span(),
-            TokenTree::Punct(ref t) => t.span(),
-            TokenTree::Literal(ref t) => t.span(),
+        match self {
+            TokenTree::Group(t) => t.span(),
+            TokenTree::Ident(t) => t.span(),
+            TokenTree::Punct(t) => t.span(),
+            TokenTree::Literal(t) => t.span(),
         }
     }
 
     /// Configures the span for *only this token*.
     ///
     /// Note that if this token is a `Group` then this method will not configure
     /// the span of each of the internal tokens, this will simply delegate to
     /// the `set_span` method of each variant.
     pub fn set_span(&mut self, span: Span) {
-        match *self {
-            TokenTree::Group(ref mut t) => t.set_span(span),
-            TokenTree::Ident(ref mut t) => t.set_span(span),
-            TokenTree::Punct(ref mut t) => t.set_span(span),
-            TokenTree::Literal(ref mut t) => t.set_span(span),
+        match self {
+            TokenTree::Group(t) => t.set_span(span),
+            TokenTree::Ident(t) => t.set_span(span),
+            TokenTree::Punct(t) => t.set_span(span),
+            TokenTree::Literal(t) => t.set_span(span),
         }
     }
 }
 
 impl From<Group> for TokenTree {
     fn from(g: Group) -> TokenTree {
         TokenTree::Group(g)
     }
@@ -508,42 +535,42 @@ impl From<Literal> for TokenTree {
         TokenTree::Literal(g)
     }
 }
 
 /// Prints the token tree as a string that is supposed to be losslessly
 /// convertible back into the same token tree (modulo spans), except for
 /// possibly `TokenTree::Group`s with `Delimiter::None` delimiters and negative
 /// numeric literals.
-impl fmt::Display for TokenTree {
+impl Display for TokenTree {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match *self {
-            TokenTree::Group(ref t) => t.fmt(f),
-            TokenTree::Ident(ref t) => t.fmt(f),
-            TokenTree::Punct(ref t) => t.fmt(f),
-            TokenTree::Literal(ref t) => t.fmt(f),
+        match self {
+            TokenTree::Group(t) => Display::fmt(t, f),
+            TokenTree::Ident(t) => Display::fmt(t, f),
+            TokenTree::Punct(t) => Display::fmt(t, f),
+            TokenTree::Literal(t) => Display::fmt(t, f),
         }
     }
 }
 
 /// Prints token tree in a form convenient for debugging.
-impl fmt::Debug for TokenTree {
+impl Debug for TokenTree {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         // Each of these has the name in the struct type in the derived debug,
         // so don't bother with an extra layer of indirection
-        match *self {
-            TokenTree::Group(ref t) => t.fmt(f),
-            TokenTree::Ident(ref t) => {
+        match self {
+            TokenTree::Group(t) => Debug::fmt(t, f),
+            TokenTree::Ident(t) => {
                 let mut debug = f.debug_struct("Ident");
                 debug.field("sym", &format_args!("{}", t));
                 imp::debug_span_field_if_nontrivial(&mut debug, t.span().inner);
                 debug.finish()
             }
-            TokenTree::Punct(ref t) => t.fmt(f),
-            TokenTree::Literal(ref t) => t.fmt(f),
+            TokenTree::Punct(t) => Debug::fmt(t, f),
+            TokenTree::Literal(t) => Debug::fmt(t, f),
         }
     }
 }
 
 /// A delimited token stream.
 ///
 /// A `Group` internally contains a `TokenStream` which is surrounded by
 /// `Delimiter`s.
@@ -646,25 +673,25 @@ impl Group {
     pub fn set_span(&mut self, span: Span) {
         self.inner.set_span(span.inner)
     }
 }
 
 /// Prints the group as a string that should be losslessly convertible back
 /// into the same group (modulo spans), except for possibly `TokenTree::Group`s
 /// with `Delimiter::None` delimiters.
-impl fmt::Display for Group {
+impl Display for Group {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Display::fmt(&self.inner, formatter)
+        Display::fmt(&self.inner, formatter)
     }
 }
 
-impl fmt::Debug for Group {
+impl Debug for Group {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Debug::fmt(&self.inner, formatter)
+        Debug::fmt(&self.inner, formatter)
     }
 }
 
 /// An `Punct` is an single punctuation character like `+`, `-` or `#`.
 ///
 /// Multicharacter operators like `+=` are represented as two instances of
 /// `Punct` with different forms of `Spacing` returned.
 #[derive(Clone)]
@@ -725,23 +752,23 @@ impl Punct {
     /// Configure the span for this punctuation character.
     pub fn set_span(&mut self, span: Span) {
         self.span = span;
     }
 }
 
 /// Prints the punctuation character as a string that should be losslessly
 /// convertible back into the same character.
-impl fmt::Display for Punct {
+impl Display for Punct {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.op.fmt(f)
+        Display::fmt(&self.op, f)
     }
 }
 
-impl fmt::Debug for Punct {
+impl Debug for Punct {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         let mut debug = fmt.debug_struct("Punct");
         debug.field("op", &self.op);
         debug.field("spacing", &self.spacing);
         imp::debug_span_field_if_nontrivial(&mut debug, self.span.inner);
         debug.finish()
     }
 }
@@ -915,25 +942,25 @@ impl Ord for Ident {
 impl Hash for Ident {
     fn hash<H: Hasher>(&self, hasher: &mut H) {
         self.to_string().hash(hasher)
     }
 }
 
 /// Prints the identifier as a string that should be losslessly convertible back
 /// into the same identifier.
-impl fmt::Display for Ident {
+impl Display for Ident {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.inner.fmt(f)
+        Display::fmt(&self.inner, f)
     }
 }
 
-impl fmt::Debug for Ident {
+impl Debug for Ident {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.inner.fmt(f)
+        Debug::fmt(&self.inner, f)
     }
 }
 
 /// A literal string (`"hello"`), byte string (`b"hello"`), character (`'a'`),
 /// byte character (`b'a'`), an integer or floating point number with or without
 /// a suffix (`1`, `1u8`, `2.3`, `2.3f32`).
 ///
 /// Boolean literals like `true` and `false` do not belong here, they are
@@ -1135,36 +1162,36 @@ impl Literal {
     /// nightly compiler, this method will always return `None`.
     ///
     /// [`proc_macro::Literal::subspan`]: https://doc.rust-lang.org/proc_macro/struct.Literal.html#method.subspan
     pub fn subspan<R: RangeBounds<usize>>(&self, range: R) -> Option<Span> {
         self.inner.subspan(range).map(Span::_new)
     }
 }
 
-impl fmt::Debug for Literal {
+impl Debug for Literal {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.inner.fmt(f)
+        Debug::fmt(&self.inner, f)
     }
 }
 
-impl fmt::Display for Literal {
+impl Display for Literal {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.inner.fmt(f)
+        Display::fmt(&self.inner, f)
     }
 }
 
 /// Public implementation details for the `TokenStream` type, such as iterators.
 pub mod token_stream {
-    use std::fmt;
+    use crate::{imp, TokenTree};
+    use std::fmt::{self, Debug};
     use std::marker;
     use std::rc::Rc;
 
     pub use crate::TokenStream;
-    use crate::{imp, TokenTree};
 
     /// An iterator over `TokenStream`'s `TokenTree`s.
     ///
     /// The iteration is "shallow", e.g. the iterator doesn't recurse into
     /// delimited groups, and returns whole groups as token trees.
     #[derive(Clone)]
     pub struct IntoIter {
         inner: imp::TokenTreeIter,
@@ -1174,19 +1201,19 @@ pub mod token_stream {
     impl Iterator for IntoIter {
         type Item = TokenTree;
 
         fn next(&mut self) -> Option<TokenTree> {
             self.inner.next()
         }
     }
 
-    impl fmt::Debug for IntoIter {
+    impl Debug for IntoIter {
         fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-            self.inner.fmt(f)
+            Debug::fmt(&self.inner, f)
         }
     }
 
     impl IntoIterator for TokenStream {
         type Item = TokenTree;
         type IntoIter = IntoIter;
 
         fn into_iter(self) -> IntoIter {
diff --git a/third_party/rust/proc-macro2/src/parse.rs b/third_party/rust/proc-macro2/src/parse.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/proc-macro2/src/parse.rs
@@ -0,0 +1,791 @@
+use crate::fallback::{
+    is_ident_continue, is_ident_start, Group, LexError, Literal, Span, TokenStream,
+};
+use crate::{Delimiter, Punct, Spacing, TokenTree};
+use std::str::{Bytes, CharIndices, Chars};
+use unicode_xid::UnicodeXID;
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub(crate) struct Cursor<'a> {
+    pub rest: &'a str,
+    #[cfg(span_locations)]
+    pub off: u32,
+}
+
+impl<'a> Cursor<'a> {
+    fn advance(&self, bytes: usize) -> Cursor<'a> {
+        let (_front, rest) = self.rest.split_at(bytes);
+        Cursor {
+            rest,
+            #[cfg(span_locations)]
+            off: self.off + _front.chars().count() as u32,
+        }
+    }
+
+    fn starts_with(&self, s: &str) -> bool {
+        self.rest.starts_with(s)
+    }
+
+    pub(crate) fn is_empty(&self) -> bool {
+        self.rest.is_empty()
+    }
+
+    fn len(&self) -> usize {
+        self.rest.len()
+    }
+
+    fn as_bytes(&self) -> &'a [u8] {
+        self.rest.as_bytes()
+    }
+
+    fn bytes(&self) -> Bytes<'a> {
+        self.rest.bytes()
+    }
+
+    fn chars(&self) -> Chars<'a> {
+        self.rest.chars()
+    }
+
+    fn char_indices(&self) -> CharIndices<'a> {
+        self.rest.char_indices()
+    }
+
+    fn parse(&self, tag: &str) -> Result<Cursor<'a>, LexError> {
+        if self.starts_with(tag) {
+            Ok(self.advance(tag.len()))
+        } else {
+            Err(LexError)
+        }
+    }
+}
+
+type PResult<'a, O> = Result<(Cursor<'a>, O), LexError>;
+
+fn skip_whitespace(input: Cursor) -> Cursor {
+    let mut s = input;
+
+    while !s.is_empty() {
+        let byte = s.as_bytes()[0];
+        if byte == b'/' {
+            if s.starts_with("//")
+                && (!s.starts_with("///") || s.starts_with("////"))
+                && !s.starts_with("//!")
+            {
+                let (cursor, _) = take_until_newline_or_eof(s);
+                s = cursor;
+                continue;
+            } else if s.starts_with("/**/") {
+                s = s.advance(4);
+                continue;
+            } else if s.starts_with("/*")
+                && (!s.starts_with("/**") || s.starts_with("/***"))
+                && !s.starts_with("/*!")
+            {
+                match block_comment(s) {
+                    Ok((rest, _)) => {
+                        s = rest;
+                        continue;
+                    }
+                    Err(LexError) => return s,
+                }
+            }
+        }
+        match byte {
+            b' ' | 0x09..=0x0d => {
+                s = s.advance(1);
+                continue;
+            }
+            b if b <= 0x7f => {}
+            _ => {
+                let ch = s.chars().next().unwrap();
+                if is_whitespace(ch) {
+                    s = s.advance(ch.len_utf8());
+                    continue;
+                }
+            }
+        }
+        return s;
+    }
+    s
+}
+
+fn block_comment(input: Cursor) -> PResult<&str> {
+    if !input.starts_with("/*") {
+        return Err(LexError);
+    }
+
+    let mut depth = 0;
+    let bytes = input.as_bytes();
+    let mut i = 0;
+    let upper = bytes.len() - 1;
+
+    while i < upper {
+        if bytes[i] == b'/' && bytes[i + 1] == b'*' {
+            depth += 1;
+            i += 1; // eat '*'
+        } else if bytes[i] == b'*' && bytes[i + 1] == b'/' {
+            depth -= 1;
+            if depth == 0 {
+                return Ok((input.advance(i + 2), &input.rest[..i + 2]));
+            }
+            i += 1; // eat '/'
+        }
+        i += 1;
+    }
+
+    Err(LexError)
+}
+
+fn is_whitespace(ch: char) -> bool {
+    // Rust treats left-to-right mark and right-to-left mark as whitespace
+    ch.is_whitespace() || ch == '\u{200e}' || ch == '\u{200f}'
+}
+
+fn word_break(input: Cursor) -> Result<Cursor, LexError> {
+    match input.chars().next() {
+        Some(ch) if UnicodeXID::is_xid_continue(ch) => Err(LexError),
+        Some(_) | None => Ok(input),
+    }
+}
+
+pub(crate) fn token_stream(mut input: Cursor) -> PResult<TokenStream> {
+    let mut trees = Vec::new();
+    let mut stack = Vec::new();
+
+    loop {
+        input = skip_whitespace(input);
+
+        if let Ok((rest, tt)) = doc_comment(input) {
+            trees.extend(tt);
+            input = rest;
+            continue;
+        }
+
+        #[cfg(span_locations)]
+        let lo = input.off;
+
+        let first = match input.bytes().next() {
+            Some(first) => first,
+            None => break,
+        };
+
+        if let Some(open_delimiter) = match first {
+            b'(' => Some(Delimiter::Parenthesis),
+            b'[' => Some(Delimiter::Bracket),
+            b'{' => Some(Delimiter::Brace),
+            _ => None,
+        } {
+            input = input.advance(1);
+            let frame = (open_delimiter, trees);
+            #[cfg(span_locations)]
+            let frame = (lo, frame);
+            stack.push(frame);
+            trees = Vec::new();
+        } else if let Some(close_delimiter) = match first {
+            b')' => Some(Delimiter::Parenthesis),
+            b']' => Some(Delimiter::Bracket),
+            b'}' => Some(Delimiter::Brace),
+            _ => None,
+        } {
+            input = input.advance(1);
+            let frame = stack.pop().ok_or(LexError)?;
+            #[cfg(span_locations)]
+            let (lo, frame) = frame;
+            let (open_delimiter, outer) = frame;
+            if open_delimiter != close_delimiter {
+                return Err(LexError);
+            }
+            let mut g = Group::new(open_delimiter, TokenStream { inner: trees });
+            g.set_span(Span {
+                #[cfg(span_locations)]
+                lo,
+                #[cfg(span_locations)]
+                hi: input.off,
+            });
+            trees = outer;
+            trees.push(TokenTree::Group(crate::Group::_new_stable(g)));
+        } else {
+            let (rest, mut tt) = leaf_token(input)?;
+            tt.set_span(crate::Span::_new_stable(Span {
+                #[cfg(span_locations)]
+                lo,
+                #[cfg(span_locations)]
+                hi: rest.off,
+            }));
+            trees.push(tt);
+            input = rest;
+        }
+    }
+
+    if stack.is_empty() {
+        Ok((input, TokenStream { inner: trees }))
+    } else {
+        Err(LexError)
+    }
+}
+
+fn leaf_token(input: Cursor) -> PResult<TokenTree> {
+    if let Ok((input, l)) = literal(input) {
+        // must be parsed before ident
+        Ok((input, TokenTree::Literal(crate::Literal::_new_stable(l))))
+    } else if let Ok((input, p)) = op(input) {
+        Ok((input, TokenTree::Punct(p)))
+    } else if let Ok((input, i)) = ident(input) {
+        Ok((input, TokenTree::Ident(i)))
+    } else {
+        Err(LexError)
+    }
+}
+
+fn ident(input: Cursor) -> PResult<crate::Ident> {
+    let raw = input.starts_with("r#");
+    let rest = input.advance((raw as usize) << 1);
+
+    let (rest, sym) = ident_not_raw(rest)?;
+
+    if !raw {
+        let ident = crate::Ident::new(sym, crate::Span::call_site());
+        return Ok((rest, ident));
+    }
+
+    if sym == "_" {
+        return Err(LexError);
+    }
+
+    let ident = crate::Ident::_new_raw(sym, crate::Span::call_site());
+    Ok((rest, ident))
+}
+
+fn ident_not_raw(input: Cursor) -> PResult<&str> {
+    let mut chars = input.char_indices();
+
+    match chars.next() {
+        Some((_, ch)) if is_ident_start(ch) => {}
+        _ => return Err(LexError),
+    }
+
+    let mut end = input.len();
+    for (i, ch) in chars {
+        if !is_ident_continue(ch) {
+            end = i;
+            break;
+        }
+    }
+
+    Ok((input.advance(end), &input.rest[..end]))
+}
+
+fn literal(input: Cursor) -> PResult<Literal> {
+    match literal_nocapture(input) {
+        Ok(a) => {
+            let end = input.len() - a.len();
+            Ok((a, Literal::_new(input.rest[..end].to_string())))
+        }
+        Err(LexError) => Err(LexError),
+    }
+}
+
+fn literal_nocapture(input: Cursor) -> Result<Cursor, LexError> {
+    if let Ok(ok) = string(input) {
+        Ok(ok)
+    } else if let Ok(ok) = byte_string(input) {
+        Ok(ok)
+    } else if let Ok(ok) = byte(input) {
+        Ok(ok)
+    } else if let Ok(ok) = character(input) {
+        Ok(ok)
+    } else if let Ok(ok) = float(input) {
+        Ok(ok)
+    } else if let Ok(ok) = int(input) {
+        Ok(ok)
+    } else {
+        Err(LexError)
+    }
+}
+
+fn literal_suffix(input: Cursor) -> Cursor {
+    match ident_not_raw(input) {
+        Ok((input, _)) => input,
+        Err(LexError) => input,
+    }
+}
+
+fn string(input: Cursor) -> Result<Cursor, LexError> {
+    if let Ok(input) = input.parse("\"") {
+        cooked_string(input)
+    } else if let Ok(input) = input.parse("r") {
+        raw_string(input)
+    } else {
+        Err(LexError)
+    }
+}
+
+fn cooked_string(input: Cursor) -> Result<Cursor, LexError> {
+    let mut chars = input.char_indices().peekable();
+
+    while let Some((i, ch)) = chars.next() {
+        match ch {
+            '"' => {
+                let input = input.advance(i + 1);
+                return Ok(literal_suffix(input));
+            }
+            '\r' => {
+                if let Some((_, '\n')) = chars.next() {
+                    // ...
+                } else {
+                    break;
+                }
+            }
+            '\\' => match chars.next() {
+                Some((_, 'x')) => {
+                    if !backslash_x_char(&mut chars) {
+                        break;
+                    }
+                }
+                Some((_, 'n')) | Some((_, 'r')) | Some((_, 't')) | Some((_, '\\'))
+                | Some((_, '\'')) | Some((_, '"')) | Some((_, '0')) => {}
+                Some((_, 'u')) => {
+                    if !backslash_u(&mut chars) {
+                        break;
+                    }
+                }
+                Some((_, '\n')) | Some((_, '\r')) => {
+                    while let Some(&(_, ch)) = chars.peek() {
+                        if ch.is_whitespace() {
+                            chars.next();
+                        } else {
+                            break;
+                        }
+                    }
+                }
+                _ => break,
+            },
+            _ch => {}
+        }
+    }
+    Err(LexError)
+}
+
+fn byte_string(input: Cursor) -> Result<Cursor, LexError> {
+    if let Ok(input) = input.parse("b\"") {
+        cooked_byte_string(input)
+    } else if let Ok(input) = input.parse("br") {
+        raw_string(input)
+    } else {
+        Err(LexError)
+    }
+}
+
+fn cooked_byte_string(mut input: Cursor) -> Result<Cursor, LexError> {
+    let mut bytes = input.bytes().enumerate();
+    'outer: while let Some((offset, b)) = bytes.next() {
+        match b {
+            b'"' => {
+                let input = input.advance(offset + 1);
+                return Ok(literal_suffix(input));
+            }
+            b'\r' => {
+                if let Some((_, b'\n')) = bytes.next() {
+                    // ...
+                } else {
+                    break;
+                }
+            }
+            b'\\' => match bytes.next() {
+                Some((_, b'x')) => {
+                    if !backslash_x_byte(&mut bytes) {
+                        break;
+                    }
+                }
+                Some((_, b'n')) | Some((_, b'r')) | Some((_, b't')) | Some((_, b'\\'))
+                | Some((_, b'0')) | Some((_, b'\'')) | Some((_, b'"')) => {}
+                Some((newline, b'\n')) | Some((newline, b'\r')) => {
+                    let rest = input.advance(newline + 1);
+                    for (offset, ch) in rest.char_indices() {
+                        if !ch.is_whitespace() {
+                            input = rest.advance(offset);
+                            bytes = input.bytes().enumerate();
+                            continue 'outer;
+                        }
+                    }
+                    break;
+                }
+                _ => break,
+            },
+            b if b < 0x80 => {}
+            _ => break,
+        }
+    }
+    Err(LexError)
+}
+
+fn raw_string(input: Cursor) -> Result<Cursor, LexError> {
+    let mut chars = input.char_indices();
+    let mut n = 0;
+    while let Some((i, ch)) = chars.next() {
+        match ch {
+            '"' => {
+                n = i;
+                break;
+            }
+            '#' => {}
+            _ => return Err(LexError),
+        }
+    }
+    for (i, ch) in chars {
+        match ch {
+            '"' if input.rest[i + 1..].starts_with(&input.rest[..n]) => {
+                let rest = input.advance(i + 1 + n);
+                return Ok(literal_suffix(rest));
+            }
+            '\r' => {}
+            _ => {}
+        }
+    }
+    Err(LexError)
+}
+
+fn byte(input: Cursor) -> Result<Cursor, LexError> {
+    let input = input.parse("b'")?;
+    let mut bytes = input.bytes().enumerate();
+    let ok = match bytes.next().map(|(_, b)| b) {
+        Some(b'\\') => match bytes.next().map(|(_, b)| b) {
+            Some(b'x') => backslash_x_byte(&mut bytes),
+            Some(b'n') | Some(b'r') | Some(b't') | Some(b'\\') | Some(b'0') | Some(b'\'')
+            | Some(b'"') => true,
+            _ => false,
+        },
+        b => b.is_some(),
+    };
+    if !ok {
+        return Err(LexError);
+    }
+    let (offset, _) = bytes.next().ok_or(LexError)?;
+    if !input.chars().as_str().is_char_boundary(offset) {
+        return Err(LexError);
+    }
+    let input = input.advance(offset).parse("'")?;
+    Ok(literal_suffix(input))
+}
+
+fn character(input: Cursor) -> Result<Cursor, LexError> {
+    let input = input.parse("'")?;
+    let mut chars = input.char_indices();
+    let ok = match chars.next().map(|(_, ch)| ch) {
+        Some('\\') => match chars.next().map(|(_, ch)| ch) {
+            Some('x') => backslash_x_char(&mut chars),
+            Some('u') => backslash_u(&mut chars),
+            Some('n') | Some('r') | Some('t') | Some('\\') | Some('0') | Some('\'') | Some('"') => {
+                true
+            }
+            _ => false,
+        },
+        ch => ch.is_some(),
+    };
+    if !ok {
+        return Err(LexError);
+    }
+    let (idx, _) = chars.next().ok_or(LexError)?;
+    let input = input.advance(idx).parse("'")?;
+    Ok(literal_suffix(input))
+}
+
+macro_rules! next_ch {
+    ($chars:ident @ $pat:pat $(| $rest:pat)*) => {
+        match $chars.next() {
+            Some((_, ch)) => match ch {
+                $pat $(| $rest)* => ch,
+                _ => return false,
+            },
+            None => return false,
+        }
+    };
+}
+
+fn backslash_x_char<I>(chars: &mut I) -> bool
+where
+    I: Iterator<Item = (usize, char)>,
+{
+    next_ch!(chars @ '0'..='7');
+    next_ch!(chars @ '0'..='9' | 'a'..='f' | 'A'..='F');
+    true
+}
+
+fn backslash_x_byte<I>(chars: &mut I) -> bool
+where
+    I: Iterator<Item = (usize, u8)>,
+{
+    next_ch!(chars @ b'0'..=b'9' | b'a'..=b'f' | b'A'..=b'F');
+    next_ch!(chars @ b'0'..=b'9' | b'a'..=b'f' | b'A'..=b'F');
+    true
+}
+
+fn backslash_u<I>(chars: &mut I) -> bool
+where
+    I: Iterator<Item = (usize, char)>,
+{
+    next_ch!(chars @ '{');
+    next_ch!(chars @ '0'..='9' | 'a'..='f' | 'A'..='F');
+    loop {
+        let c = next_ch!(chars @ '0'..='9' | 'a'..='f' | 'A'..='F' | '_' | '}');
+        if c == '}' {
+            return true;
+        }
+    }
+}
+
+fn float(input: Cursor) -> Result<Cursor, LexError> {
+    let mut rest = float_digits(input)?;
+    if let Some(ch) = rest.chars().next() {
+        if is_ident_start(ch) {
+            rest = ident_not_raw(rest)?.0;
+        }
+    }
+    word_break(rest)
+}
+
+fn float_digits(input: Cursor) -> Result<Cursor, LexError> {
+    let mut chars = input.chars().peekable();
+    match chars.next() {
+        Some(ch) if ch >= '0' && ch <= '9' => {}
+        _ => return Err(LexError),
+    }
+
+    let mut len = 1;
+    let mut has_dot = false;
+    let mut has_exp = false;
+    while let Some(&ch) = chars.peek() {
+        match ch {
+            '0'..='9' | '_' => {
+                chars.next();
+                len += 1;
+            }
+            '.' => {
+                if has_dot {
+                    break;
+                }
+                chars.next();
+                if chars
+                    .peek()
+                    .map(|&ch| ch == '.' || is_ident_start(ch))
+                    .unwrap_or(false)
+                {
+                    return Err(LexError);
+                }
+                len += 1;
+                has_dot = true;
+            }
+            'e' | 'E' => {
+                chars.next();
+                len += 1;
+                has_exp = true;
+                break;
+            }
+            _ => break,
+        }
+    }
+
+    let rest = input.advance(len);
+    if !(has_dot || has_exp || rest.starts_with("f32") || rest.starts_with("f64")) {
+        return Err(LexError);
+    }
+
+    if has_exp {
+        let mut has_exp_value = false;
+        while let Some(&ch) = chars.peek() {
+            match ch {
+                '+' | '-' => {
+                    if has_exp_value {
+                        break;
+                    }
+                    chars.next();
+                    len += 1;
+                }
+                '0'..='9' => {
+                    chars.next();
+                    len += 1;
+                    has_exp_value = true;
+                }
+                '_' => {
+                    chars.next();
+                    len += 1;
+                }
+                _ => break,
+            }
+        }
+        if !has_exp_value {
+            return Err(LexError);
+        }
+    }
+
+    Ok(input.advance(len))
+}
+
+fn int(input: Cursor) -> Result<Cursor, LexError> {
+    let mut rest = digits(input)?;
+    if let Some(ch) = rest.chars().next() {
+        if is_ident_start(ch) {
+            rest = ident_not_raw(rest)?.0;
+        }
+    }
+    word_break(rest)
+}
+
+fn digits(mut input: Cursor) -> Result<Cursor, LexError> {
+    let base = if input.starts_with("0x") {
+        input = input.advance(2);
+        16
+    } else if input.starts_with("0o") {
+        input = input.advance(2);
+        8
+    } else if input.starts_with("0b") {
+        input = input.advance(2);
+        2
+    } else {
+        10
+    };
+
+    let mut len = 0;
+    let mut empty = true;
+    for b in input.bytes() {
+        let digit = match b {
+            b'0'..=b'9' => (b - b'0') as u64,
+            b'a'..=b'f' => 10 + (b - b'a') as u64,
+            b'A'..=b'F' => 10 + (b - b'A') as u64,
+            b'_' => {
+                if empty && base == 10 {
+                    return Err(LexError);
+                }
+                len += 1;
+                continue;
+            }
+            _ => break,
+        };
+        if digit >= base {
+            return Err(LexError);
+        }
+        len += 1;
+        empty = false;
+    }
+    if empty {
+        Err(LexError)
+    } else {
+        Ok(input.advance(len))
+    }
+}
+
+fn op(input: Cursor) -> PResult<Punct> {
+    match op_char(input) {
+        Ok((rest, '\'')) => {
+            ident(rest)?;
+            Ok((rest, Punct::new('\'', Spacing::Joint)))
+        }
+        Ok((rest, ch)) => {
+            let kind = match op_char(rest) {
+                Ok(_) => Spacing::Joint,
+                Err(LexError) => Spacing::Alone,
+            };
+            Ok((rest, Punct::new(ch, kind)))
+        }
+        Err(LexError) => Err(LexError),
+    }
+}
+
+fn op_char(input: Cursor) -> PResult<char> {
+    if input.starts_with("//") || input.starts_with("/*") {
+        // Do not accept `/` of a comment as an op.
+        return Err(LexError);
+    }
+
+    let mut chars = input.chars();
+    let first = match chars.next() {
+        Some(ch) => ch,
+        None => {
+            return Err(LexError);
+        }
+    };
+    let recognized = "~!@#$%^&*-=+|;:,<.>/?'";
+    if recognized.contains(first) {
+        Ok((input.advance(first.len_utf8()), first))
+    } else {
+        Err(LexError)
+    }
+}
+
+fn doc_comment(input: Cursor) -> PResult<Vec<TokenTree>> {
+    #[cfg(span_locations)]
+    let lo = input.off;
+    let (rest, (comment, inner)) = doc_comment_contents(input)?;
+    let span = crate::Span::_new_stable(Span {
+        #[cfg(span_locations)]
+        lo,
+        #[cfg(span_locations)]
+        hi: rest.off,
+    });
+
+    let mut scan_for_bare_cr = comment;
+    while let Some(cr) = scan_for_bare_cr.find('\r') {
+        let rest = &scan_for_bare_cr[cr + 1..];
+        if !rest.starts_with('\n') {
+            return Err(LexError);
+        }
+        scan_for_bare_cr = rest;
+    }
+
+    let mut trees = Vec::new();
+    trees.push(TokenTree::Punct(Punct::new('#', Spacing::Alone)));
+    if inner {
+        trees.push(Punct::new('!', Spacing::Alone).into());
+    }
+    let mut stream = vec![
+        TokenTree::Ident(crate::Ident::new("doc", span)),
+        TokenTree::Punct(Punct::new('=', Spacing::Alone)),
+        TokenTree::Literal(crate::Literal::string(comment)),
+    ];
+    for tt in stream.iter_mut() {
+        tt.set_span(span);
+    }
+    let group = Group::new(Delimiter::Bracket, stream.into_iter().collect());
+    trees.push(crate::Group::_new_stable(group).into());
+    for tt in trees.iter_mut() {
+        tt.set_span(span);
+    }
+    Ok((rest, trees))
+}
+
+fn doc_comment_contents(input: Cursor) -> PResult<(&str, bool)> {
+    if input.starts_with("//!") {
+        let input = input.advance(3);
+        let (input, s) = take_until_newline_or_eof(input);
+        Ok((input, (s, true)))
+    } else if input.starts_with("/*!") {
+        let (input, s) = block_comment(input)?;
+        Ok((input, (&s[3..s.len() - 2], true)))
+    } else if input.starts_with("///") {
+        let input = input.advance(3);
+        if input.starts_with("/") {
+            return Err(LexError);
+        }
+        let (input, s) = take_until_newline_or_eof(input);
+        Ok((input, (s, false)))
+    } else if input.starts_with("/**") && !input.rest[3..].starts_with('*') {
+        let (input, s) = block_comment(input)?;
+        Ok((input, (&s[3..s.len() - 2], false)))
+    } else {
+        Err(LexError)
+    }
+}
+
+fn take_until_newline_or_eof(input: Cursor) -> (Cursor, &str) {
+    let chars = input.char_indices();
+
+    for (i, ch) in chars {
+        if ch == '\n' {
+            return (input.advance(i), &input.rest[..i]);
+        } else if ch == '\r' && input.rest[i + 1..].starts_with('\n') {
+            return (input.advance(i + 1), &input.rest[..i]);
+        }
+    }
+
+    (input.advance(input.len()), input.rest)
+}
diff --git a/third_party/rust/proc-macro2/src/strnom.rs b/third_party/rust/proc-macro2/src/strnom.rs
deleted file mode 100644
--- a/third_party/rust/proc-macro2/src/strnom.rs
+++ /dev/null
@@ -1,391 +0,0 @@
-//! Adapted from [`nom`](https://github.com/Geal/nom).
-
-use crate::fallback::LexError;
-use std::str::{Bytes, CharIndices, Chars};
-use unicode_xid::UnicodeXID;
-
-#[derive(Copy, Clone, Eq, PartialEq)]
-pub struct Cursor<'a> {
-    pub rest: &'a str,
-    #[cfg(span_locations)]
-    pub off: u32,
-}
-
-impl<'a> Cursor<'a> {
-    #[cfg(not(span_locations))]
-    pub fn advance(&self, amt: usize) -> Cursor<'a> {
-        Cursor {
-            rest: &self.rest[amt..],
-        }
-    }
-    #[cfg(span_locations)]
-    pub fn advance(&self, amt: usize) -> Cursor<'a> {
-        Cursor {
-            rest: &self.rest[amt..],
-            off: self.off + (amt as u32),
-        }
-    }
-
-    pub fn find(&self, p: char) -> Option<usize> {
-        self.rest.find(p)
-    }
-
-    pub fn starts_with(&self, s: &str) -> bool {
-        self.rest.starts_with(s)
-    }
-
-    pub fn is_empty(&self) -> bool {
-        self.rest.is_empty()
-    }
-
-    pub fn len(&self) -> usize {
-        self.rest.len()
-    }
-
-    pub fn as_bytes(&self) -> &'a [u8] {
-        self.rest.as_bytes()
-    }
-
-    pub fn bytes(&self) -> Bytes<'a> {
-        self.rest.bytes()
-    }
-
-    pub fn chars(&self) -> Chars<'a> {
-        self.rest.chars()
-    }
-
-    pub fn char_indices(&self) -> CharIndices<'a> {
-        self.rest.char_indices()
-    }
-}
-
-pub type PResult<'a, O> = Result<(Cursor<'a>, O), LexError>;
-
-pub fn whitespace(input: Cursor) -> PResult<()> {
-    if input.is_empty() {
-        return Err(LexError);
-    }
-
-    let bytes = input.as_bytes();
-    let mut i = 0;
-    while i < bytes.len() {
-        let s = input.advance(i);
-        if bytes[i] == b'/' {
-            if s.starts_with("//")
-                && (!s.starts_with("///") || s.starts_with("////"))
-                && !s.starts_with("//!")
-            {
-                if let Some(len) = s.find('\n') {
-                    i += len + 1;
-                    continue;
-                }
-                break;
-            } else if s.starts_with("/**/") {
-                i += 4;
-                continue;
-            } else if s.starts_with("/*")
-                && (!s.starts_with("/**") || s.starts_with("/***"))
-                && !s.starts_with("/*!")
-            {
-                let (_, com) = block_comment(s)?;
-                i += com.len();
-                continue;
-            }
-        }
-        match bytes[i] {
-            b' ' | 0x09..=0x0d => {
-                i += 1;
-                continue;
-            }
-            b if b <= 0x7f => {}
-            _ => {
-                let ch = s.chars().next().unwrap();
-                if is_whitespace(ch) {
-                    i += ch.len_utf8();
-                    continue;
-                }
-            }
-        }
-        return if i > 0 { Ok((s, ())) } else { Err(LexError) };
-    }
-    Ok((input.advance(input.len()), ()))
-}
-
-pub fn block_comment(input: Cursor) -> PResult<&str> {
-    if !input.starts_with("/*") {
-        return Err(LexError);
-    }
-
-    let mut depth = 0;
-    let bytes = input.as_bytes();
-    let mut i = 0;
-    let upper = bytes.len() - 1;
-    while i < upper {
-        if bytes[i] == b'/' && bytes[i + 1] == b'*' {
-            depth += 1;
-            i += 1; // eat '*'
-        } else if bytes[i] == b'*' && bytes[i + 1] == b'/' {
-            depth -= 1;
-            if depth == 0 {
-                return Ok((input.advance(i + 2), &input.rest[..i + 2]));
-            }
-            i += 1; // eat '/'
-        }
-        i += 1;
-    }
-    Err(LexError)
-}
-
-pub fn skip_whitespace(input: Cursor) -> Cursor {
-    match whitespace(input) {
-        Ok((rest, _)) => rest,
-        Err(LexError) => input,
-    }
-}
-
-fn is_whitespace(ch: char) -> bool {
-    // Rust treats left-to-right mark and right-to-left mark as whitespace
-    ch.is_whitespace() || ch == '\u{200e}' || ch == '\u{200f}'
-}
-
-pub fn word_break(input: Cursor) -> PResult<()> {
-    match input.chars().next() {
-        Some(ch) if UnicodeXID::is_xid_continue(ch) => Err(LexError),
-        Some(_) | None => Ok((input, ())),
-    }
-}
-
-macro_rules! named {
-    ($name:ident -> $o:ty, $submac:ident!( $($args:tt)* )) => {
-        fn $name<'a>(i: Cursor<'a>) -> $crate::strnom::PResult<'a, $o> {
-            $submac!(i, $($args)*)
-        }
-    };
-}
-
-macro_rules! alt {
-    ($i:expr, $e:ident | $($rest:tt)*) => {
-        alt!($i, call!($e) | $($rest)*)
-    };
-
-    ($i:expr, $subrule:ident!( $($args:tt)*) | $($rest:tt)*) => {
-        match $subrule!($i, $($args)*) {
-            res @ Ok(_) => res,
-            _ => alt!($i, $($rest)*)
-        }
-    };
-
-    ($i:expr, $subrule:ident!( $($args:tt)* ) => { $gen:expr } | $($rest:tt)+) => {
-        match $subrule!($i, $($args)*) {
-            Ok((i, o)) => Ok((i, $gen(o))),
-            Err(LexError) => alt!($i, $($rest)*)
-        }
-    };
-
-    ($i:expr, $e:ident => { $gen:expr } | $($rest:tt)*) => {
-        alt!($i, call!($e) => { $gen } | $($rest)*)
-    };
-
-    ($i:expr, $e:ident => { $gen:expr }) => {
-        alt!($i, call!($e) => { $gen })
-    };
-
-    ($i:expr, $subrule:ident!( $($args:tt)* ) => { $gen:expr }) => {
-        match $subrule!($i, $($args)*) {
-            Ok((i, o)) => Ok((i, $gen(o))),
-            Err(LexError) => Err(LexError),
-        }
-    };
-
-    ($i:expr, $e:ident) => {
-        alt!($i, call!($e))
-    };
-
-    ($i:expr, $subrule:ident!( $($args:tt)*)) => {
-        $subrule!($i, $($args)*)
-    };
-}
-
-macro_rules! do_parse {
-    ($i:expr, ( $($rest:expr),* )) => {
-        Ok(($i, ( $($rest),* )))
-    };
-
-    ($i:expr, $e:ident >> $($rest:tt)*) => {
-        do_parse!($i, call!($e) >> $($rest)*)
-    };
-
-    ($i:expr, $submac:ident!( $($args:tt)* ) >> $($rest:tt)*) => {
-        match $submac!($i, $($args)*) {
-            Err(LexError) => Err(LexError),
-            Ok((i, _)) => do_parse!(i, $($rest)*),
-        }
-    };
-
-    ($i:expr, $field:ident : $e:ident >> $($rest:tt)*) => {
-        do_parse!($i, $field: call!($e) >> $($rest)*)
-    };
-
-    ($i:expr, $field:ident : $submac:ident!( $($args:tt)* ) >> $($rest:tt)*) => {
-        match $submac!($i, $($args)*) {
-            Err(LexError) => Err(LexError),
-            Ok((i, o)) => {
-                let $field = o;
-                do_parse!(i, $($rest)*)
-            },
-        }
-    };
-}
-
-macro_rules! peek {
-    ($i:expr, $submac:ident!( $($args:tt)* )) => {
-        match $submac!($i, $($args)*) {
-            Ok((_, o)) => Ok(($i, o)),
-            Err(LexError) => Err(LexError),
-        }
-    };
-}
-
-macro_rules! call {
-    ($i:expr, $fun:expr $(, $args:expr)*) => {
-        $fun($i $(, $args)*)
-    };
-}
-
-macro_rules! option {
-    ($i:expr, $f:expr) => {
-        match $f($i) {
-            Ok((i, o)) => Ok((i, Some(o))),
-            Err(LexError) => Ok(($i, None)),
-        }
-    };
-}
-
-macro_rules! take_until_newline_or_eof {
-    ($i:expr,) => {{
-        if $i.len() == 0 {
-            Ok(($i, ""))
-        } else {
-            match $i.find('\n') {
-                Some(i) => Ok(($i.advance(i), &$i.rest[..i])),
-                None => Ok(($i.advance($i.len()), &$i.rest[..$i.len()])),
-            }
-        }
-    }};
-}
-
-macro_rules! tuple {
-    ($i:expr, $($rest:tt)*) => {
-        tuple_parser!($i, (), $($rest)*)
-    };
-}
-
-/// Do not use directly. Use `tuple!`.
-macro_rules! tuple_parser {
-    ($i:expr, ($($parsed:tt),*), $e:ident, $($rest:tt)*) => {
-        tuple_parser!($i, ($($parsed),*), call!($e), $($rest)*)
-    };
-
-    ($i:expr, (), $submac:ident!( $($args:tt)* ), $($rest:tt)*) => {
-        match $submac!($i, $($args)*) {
-            Err(LexError) => Err(LexError),
-            Ok((i, o)) => tuple_parser!(i, (o), $($rest)*),
-        }
-    };
-
-    ($i:expr, ($($parsed:tt)*), $submac:ident!( $($args:tt)* ), $($rest:tt)*) => {
-        match $submac!($i, $($args)*) {
-            Err(LexError) => Err(LexError),
-            Ok((i, o)) => tuple_parser!(i, ($($parsed)* , o), $($rest)*),
-        }
-    };
-
-    ($i:expr, ($($parsed:tt),*), $e:ident) => {
-        tuple_parser!($i, ($($parsed),*), call!($e))
-    };
-
-    ($i:expr, (), $submac:ident!( $($args:tt)* )) => {
-        $submac!($i, $($args)*)
-    };
-
-    ($i:expr, ($($parsed:expr),*), $submac:ident!( $($args:tt)* )) => {
-        match $submac!($i, $($args)*) {
-            Err(LexError) => Err(LexError),
-            Ok((i, o)) => Ok((i, ($($parsed),*, o)))
-        }
-    };
-
-    ($i:expr, ($($parsed:expr),*)) => {
-        Ok(($i, ($($parsed),*)))
-    };
-}
-
-macro_rules! not {
-    ($i:expr, $submac:ident!( $($args:tt)* )) => {
-        match $submac!($i, $($args)*) {
-            Ok((_, _)) => Err(LexError),
-            Err(LexError) => Ok(($i, ())),
-        }
-    };
-}
-
-macro_rules! tag {
-    ($i:expr, $tag:expr) => {
-        if $i.starts_with($tag) {
-            Ok(($i.advance($tag.len()), &$i.rest[..$tag.len()]))
-        } else {
-            Err(LexError)
-        }
-    };
-}
-
-macro_rules! punct {
-    ($i:expr, $punct:expr) => {
-        $crate::strnom::punct($i, $punct)
-    };
-}
-
-/// Do not use directly. Use `punct!`.
-pub fn punct<'a>(input: Cursor<'a>, token: &'static str) -> PResult<'a, &'a str> {
-    let input = skip_whitespace(input);
-    if input.starts_with(token) {
-        Ok((input.advance(token.len()), token))
-    } else {
-        Err(LexError)
-    }
-}
-
-macro_rules! preceded {
-    ($i:expr, $submac:ident!( $($args:tt)* ), $submac2:ident!( $($args2:tt)* )) => {
-        match tuple!($i, $submac!($($args)*), $submac2!($($args2)*)) {
-            Ok((remaining, (_, o))) => Ok((remaining, o)),
-            Err(LexError) => Err(LexError),
-        }
-    };
-
-    ($i:expr, $submac:ident!( $($args:tt)* ), $g:expr) => {
-        preceded!($i, $submac!($($args)*), call!($g))
-    };
-}
-
-macro_rules! delimited {
-    ($i:expr, $submac:ident!( $($args:tt)* ), $($rest:tt)+) => {
-        match tuple_parser!($i, (), $submac!($($args)*), $($rest)*) {
-            Err(LexError) => Err(LexError),
-            Ok((i1, (_, o, _))) => Ok((i1, o))
-        }
-    };
-}
-
-macro_rules! map {
-    ($i:expr, $submac:ident!( $($args:tt)* ), $g:expr) => {
-        match $submac!($i, $($args)*) {
-            Err(LexError) => Err(LexError),
-            Ok((i, o)) => Ok((i, call!(o, $g)))
-        }
-    };
-
-    ($i:expr, $f:expr, $g:expr) => {
-        map!($i, call!($f), $g)
-    };
-}
diff --git a/third_party/rust/proc-macro2/src/wrapper.rs b/third_party/rust/proc-macro2/src/wrapper.rs
--- a/third_party/rust/proc-macro2/src/wrapper.rs
+++ b/third_party/rust/proc-macro2/src/wrapper.rs
@@ -1,96 +1,39 @@
-use std::fmt;
-use std::iter;
+use crate::detection::inside_proc_macro;
+use crate::{fallback, Delimiter, Punct, Spacing, TokenTree};
+use std::fmt::{self, Debug, Display};
+use std::iter::FromIterator;
 use std::ops::RangeBounds;
-use std::panic::{self, PanicInfo};
+use std::panic;
 #[cfg(super_unstable)]
 use std::path::PathBuf;
 use std::str::FromStr;
 
-use crate::{fallback, Delimiter, Punct, Spacing, TokenTree};
-
 #[derive(Clone)]
-pub enum TokenStream {
+pub(crate) enum TokenStream {
     Compiler(DeferredTokenStream),
     Fallback(fallback::TokenStream),
 }
 
 // Work around https://github.com/rust-lang/rust/issues/65080.
 // In `impl Extend<TokenTree> for TokenStream` which is used heavily by quote,
 // we hold on to the appended tokens and do proc_macro::TokenStream::extend as
 // late as possible to batch together consecutive uses of the Extend impl.
 #[derive(Clone)]
-pub struct DeferredTokenStream {
+pub(crate) struct DeferredTokenStream {
     stream: proc_macro::TokenStream,
     extra: Vec<proc_macro::TokenTree>,
 }
 
-pub enum LexError {
+pub(crate) enum LexError {
     Compiler(proc_macro::LexError),
     Fallback(fallback::LexError),
 }
 
-fn nightly_works() -> bool {
-    use std::sync::atomic::*;
-    use std::sync::Once;
-
-    static WORKS: AtomicUsize = AtomicUsize::new(0);
-    static INIT: Once = Once::new();
-
-    match WORKS.load(Ordering::SeqCst) {
-        1 => return false,
-        2 => return true,
-        _ => {}
-    }
-
-    // Swap in a null panic hook to avoid printing "thread panicked" to stderr,
-    // then use catch_unwind to determine whether the compiler's proc_macro is
-    // working. When proc-macro2 is used from outside of a procedural macro all
-    // of the proc_macro crate's APIs currently panic.
-    //
-    // The Once is to prevent the possibility of this ordering:
-    //
-    //     thread 1 calls take_hook, gets the user's original hook
-    //     thread 1 calls set_hook with the null hook
-    //     thread 2 calls take_hook, thinks null hook is the original hook
-    //     thread 2 calls set_hook with the null hook
-    //     thread 1 calls set_hook with the actual original hook
-    //     thread 2 calls set_hook with what it thinks is the original hook
-    //
-    // in which the user's hook has been lost.
-    //
-    // There is still a race condition where a panic in a different thread can
-    // happen during the interval that the user's original panic hook is
-    // unregistered such that their hook is incorrectly not called. This is
-    // sufficiently unlikely and less bad than printing panic messages to stderr
-    // on correct use of this crate. Maybe there is a libstd feature request
-    // here. For now, if a user needs to guarantee that this failure mode does
-    // not occur, they need to call e.g. `proc_macro2::Span::call_site()` from
-    // the main thread before launching any other threads.
-    INIT.call_once(|| {
-        type PanicHook = dyn Fn(&PanicInfo) + Sync + Send + 'static;
-
-        let null_hook: Box<PanicHook> = Box::new(|_panic_info| { /* ignore */ });
-        let sanity_check = &*null_hook as *const PanicHook;
-        let original_hook = panic::take_hook();
-        panic::set_hook(null_hook);
-
-        let works = panic::catch_unwind(|| proc_macro::Span::call_site()).is_ok();
-        WORKS.store(works as usize + 1, Ordering::SeqCst);
-
-        let hopefully_null_hook = panic::take_hook();
-        panic::set_hook(original_hook);
-        if sanity_check != &*hopefully_null_hook {
-            panic!("observed race condition in proc_macro2::nightly_works");
-        }
-    });
-    nightly_works()
-}
-
 fn mismatch() -> ! {
     panic!("stable/nightly mismatch")
 }
 
 impl DeferredTokenStream {
     fn new(stream: proc_macro::TokenStream) -> Self {
         DeferredTokenStream {
             stream,
@@ -98,28 +41,33 @@ impl DeferredTokenStream {
         }
     }
 
     fn is_empty(&self) -> bool {
         self.stream.is_empty() && self.extra.is_empty()
     }
 
     fn evaluate_now(&mut self) {
-        self.stream.extend(self.extra.drain(..));
+        // If-check provides a fast short circuit for the common case of `extra`
+        // being empty, which saves a round trip over the proc macro bridge.
+        // Improves macro expansion time in winrt by 6% in debug mode.
+        if !self.extra.is_empty() {
+            self.stream.extend(self.extra.drain(..));
+        }
     }
 
     fn into_token_stream(mut self) -> proc_macro::TokenStream {
         self.evaluate_now();
         self.stream
     }
 }
 
 impl TokenStream {
     pub fn new() -> TokenStream {
-        if nightly_works() {
+        if inside_proc_macro() {
             TokenStream::Compiler(DeferredTokenStream::new(proc_macro::TokenStream::new()))
         } else {
             TokenStream::Fallback(fallback::TokenStream::new())
         }
     }
 
     pub fn is_empty(&self) -> bool {
         match self {
@@ -142,31 +90,37 @@ impl TokenStream {
         }
     }
 }
 
 impl FromStr for TokenStream {
     type Err = LexError;
 
     fn from_str(src: &str) -> Result<TokenStream, LexError> {
-        if nightly_works() {
+        if inside_proc_macro() {
             Ok(TokenStream::Compiler(DeferredTokenStream::new(
-                src.parse()?,
+                proc_macro_parse(src)?,
             )))
         } else {
             Ok(TokenStream::Fallback(src.parse()?))
         }
     }
 }
 
-impl fmt::Display for TokenStream {
+// Work around https://github.com/rust-lang/rust/issues/58736.
+fn proc_macro_parse(src: &str) -> Result<proc_macro::TokenStream, LexError> {
+    panic::catch_unwind(|| src.parse().map_err(LexError::Compiler))
+        .unwrap_or(Err(LexError::Fallback(fallback::LexError)))
+}
+
+impl Display for TokenStream {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            TokenStream::Compiler(tts) => tts.clone().into_token_stream().fmt(f),
-            TokenStream::Fallback(tts) => tts.fmt(f),
+            TokenStream::Compiler(tts) => Display::fmt(&tts.clone().into_token_stream(), f),
+            TokenStream::Fallback(tts) => Display::fmt(tts, f),
         }
     }
 }
 
 impl From<proc_macro::TokenStream> for TokenStream {
     fn from(inner: proc_macro::TokenStream) -> TokenStream {
         TokenStream::Compiler(DeferredTokenStream::new(inner))
     }
@@ -182,17 +136,17 @@ impl From<TokenStream> for proc_macro::T
 }
 
 impl From<fallback::TokenStream> for TokenStream {
     fn from(inner: fallback::TokenStream) -> TokenStream {
         TokenStream::Fallback(inner)
     }
 }
 
-// Assumes nightly_works().
+// Assumes inside_proc_macro().
 fn into_compiler_token(token: TokenTree) -> proc_macro::TokenTree {
     match token {
         TokenTree::Group(tt) => tt.inner.unwrap_nightly().into(),
         TokenTree::Punct(tt) => {
             let spacing = match tt.spacing() {
                 Spacing::Joint => proc_macro::Spacing::Joint,
                 Spacing::Alone => proc_macro::Spacing::Alone,
             };
@@ -202,37 +156,37 @@ fn into_compiler_token(token: TokenTree)
         }
         TokenTree::Ident(tt) => tt.inner.unwrap_nightly().into(),
         TokenTree::Literal(tt) => tt.inner.unwrap_nightly().into(),
     }
 }
 
 impl From<TokenTree> for TokenStream {
     fn from(token: TokenTree) -> TokenStream {
-        if nightly_works() {
+        if inside_proc_macro() {
             TokenStream::Compiler(DeferredTokenStream::new(into_compiler_token(token).into()))
         } else {
             TokenStream::Fallback(token.into())
         }
     }
 }
 
-impl iter::FromIterator<TokenTree> for TokenStream {
+impl FromIterator<TokenTree> for TokenStream {
     fn from_iter<I: IntoIterator<Item = TokenTree>>(trees: I) -> Self {
-        if nightly_works() {
+        if inside_proc_macro() {
             TokenStream::Compiler(DeferredTokenStream::new(
                 trees.into_iter().map(into_compiler_token).collect(),
             ))
         } else {
             TokenStream::Fallback(trees.into_iter().collect())
         }
     }
 }
 
-impl iter::FromIterator<TokenStream> for TokenStream {
+impl FromIterator<TokenStream> for TokenStream {
     fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self {
         let mut streams = streams.into_iter();
         match streams.next() {
             Some(TokenStream::Compiler(mut first)) => {
                 first.evaluate_now();
                 first.stream.extend(streams.map(|s| match s {
                     TokenStream::Compiler(s) => s.into_token_stream(),
                     TokenStream::Fallback(_) => mismatch(),
@@ -247,75 +201,76 @@ impl iter::FromIterator<TokenStream> for
                 TokenStream::Fallback(first)
             }
             None => TokenStream::new(),
         }
     }
 }
 
 impl Extend<TokenTree> for TokenStream {
-    fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, streams: I) {
+    fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, stream: I) {
         match self {
             TokenStream::Compiler(tts) => {
                 // Here is the reason for DeferredTokenStream.
-                tts.extra
-                    .extend(streams.into_iter().map(into_compiler_token));
+                for token in stream {
+                    tts.extra.push(into_compiler_token(token));
+                }
             }
-            TokenStream::Fallback(tts) => tts.extend(streams),
+            TokenStream::Fallback(tts) => tts.extend(stream),
         }
     }
 }
 
 impl Extend<TokenStream> for TokenStream {
     fn extend<I: IntoIterator<Item = TokenStream>>(&mut self, streams: I) {
         match self {
             TokenStream::Compiler(tts) => {
                 tts.evaluate_now();
                 tts.stream
-                    .extend(streams.into_iter().map(|stream| stream.unwrap_nightly()));
+                    .extend(streams.into_iter().map(TokenStream::unwrap_nightly));
             }
             TokenStream::Fallback(tts) => {
-                tts.extend(streams.into_iter().map(|stream| stream.unwrap_stable()));
+                tts.extend(streams.into_iter().map(TokenStream::unwrap_stable));
             }
         }
     }
 }
 
-impl fmt::Debug for TokenStream {
+impl Debug for TokenStream {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            TokenStream::Compiler(tts) => tts.clone().into_token_stream().fmt(f),
-            TokenStream::Fallback(tts) => tts.fmt(f),
+            TokenStream::Compiler(tts) => Debug::fmt(&tts.clone().into_token_stream(), f),
+            TokenStream::Fallback(tts) => Debug::fmt(tts, f),
         }
     }
 }
 
 impl From<proc_macro::LexError> for LexError {
     fn from(e: proc_macro::LexError) -> LexError {
         LexError::Compiler(e)
     }
 }
 
 impl From<fallback::LexError> for LexError {
     fn from(e: fallback::LexError) -> LexError {
         LexError::Fallback(e)
     }
 }
 
-impl fmt::Debug for LexError {
+impl Debug for LexError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            LexError::Compiler(e) => e.fmt(f),
-            LexError::Fallback(e) => e.fmt(f),
+            LexError::Compiler(e) => Debug::fmt(e, f),
+            LexError::Fallback(e) => Debug::fmt(e, f),
         }
     }
 }
 
 #[derive(Clone)]
-pub enum TokenTreeIter {
+pub(crate) enum TokenTreeIter {
     Compiler(proc_macro::token_stream::IntoIter),
     Fallback(fallback::TokenTreeIter),
 }
 
 impl IntoIterator for TokenStream {
     type Item = TokenTree;
     type IntoIter = TokenTreeIter;
 
@@ -356,25 +311,25 @@ impl Iterator for TokenTreeIter {
     fn size_hint(&self) -> (usize, Option<usize>) {
         match self {
             TokenTreeIter::Compiler(tts) => tts.size_hint(),
             TokenTreeIter::Fallback(tts) => tts.size_hint(),
         }
     }
 }
 
-impl fmt::Debug for TokenTreeIter {
+impl Debug for TokenTreeIter {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_struct("TokenTreeIter").finish()
     }
 }
 
 #[derive(Clone, PartialEq, Eq)]
 #[cfg(super_unstable)]
-pub enum SourceFile {
+pub(crate) enum SourceFile {
     Compiler(proc_macro::SourceFile),
     Fallback(fallback::SourceFile),
 }
 
 #[cfg(super_unstable)]
 impl SourceFile {
     fn nightly(sf: proc_macro::SourceFile) -> Self {
         SourceFile::Compiler(sf)
@@ -392,68 +347,87 @@ impl SourceFile {
         match self {
             SourceFile::Compiler(a) => a.is_real(),
             SourceFile::Fallback(a) => a.is_real(),
         }
     }
 }
 
 #[cfg(super_unstable)]
-impl fmt::Debug for SourceFile {
+impl Debug for SourceFile {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            SourceFile::Compiler(a) => a.fmt(f),
-            SourceFile::Fallback(a) => a.fmt(f),
+            SourceFile::Compiler(a) => Debug::fmt(a, f),
+            SourceFile::Fallback(a) => Debug::fmt(a, f),
         }
     }
 }
 
 #[cfg(any(super_unstable, feature = "span-locations"))]
-pub struct LineColumn {
+pub(crate) struct LineColumn {
     pub line: usize,
     pub column: usize,
 }
 
 #[derive(Copy, Clone)]
-pub enum Span {
+pub(crate) enum Span {
     Compiler(proc_macro::Span),
     Fallback(fallback::Span),
 }
 
 impl Span {
     pub fn call_site() -> Span {
-        if nightly_works() {
+        if inside_proc_macro() {
             Span::Compiler(proc_macro::Span::call_site())
         } else {
             Span::Fallback(fallback::Span::call_site())
         }
     }
 
+    #[cfg(hygiene)]
+    pub fn mixed_site() -> Span {
+        if inside_proc_macro() {
+            Span::Compiler(proc_macro::Span::mixed_site())
+        } else {
+            Span::Fallback(fallback::Span::mixed_site())
+        }
+    }
+
     #[cfg(super_unstable)]
     pub fn def_site() -> Span {
-        if nightly_works() {
+        if inside_proc_macro() {
             Span::Compiler(proc_macro::Span::def_site())
         } else {
             Span::Fallback(fallback::Span::def_site())
         }
     }
 
-    #[cfg(super_unstable)]
     pub fn resolved_at(&self, other: Span) -> Span {
         match (self, other) {
+            #[cfg(hygiene)]
             (Span::Compiler(a), Span::Compiler(b)) => Span::Compiler(a.resolved_at(b)),
+
+            // Name resolution affects semantics, but location is only cosmetic
+            #[cfg(not(hygiene))]
+            (Span::Compiler(_), Span::Compiler(_)) => other,
+
             (Span::Fallback(a), Span::Fallback(b)) => Span::Fallback(a.resolved_at(b)),
             _ => mismatch(),
         }
     }
 
-    #[cfg(super_unstable)]
     pub fn located_at(&self, other: Span) -> Span {
         match (self, other) {
+            #[cfg(hygiene)]
             (Span::Compiler(a), Span::Compiler(b)) => Span::Compiler(a.located_at(b)),
+
+            // Name resolution affects semantics, but location is only cosmetic
+            #[cfg(not(hygiene))]
+            (Span::Compiler(_), Span::Compiler(_)) => *self,
+
             (Span::Fallback(a), Span::Fallback(b)) => Span::Fallback(a.located_at(b)),
             _ => mismatch(),
         }
     }
 
     pub fn unwrap(self) -> proc_macro::Span {
         match self {
             Span::Compiler(s) => s,
@@ -537,36 +511,36 @@ impl From<proc_macro::Span> for crate::S
 }
 
 impl From<fallback::Span> for Span {
     fn from(inner: fallback::Span) -> Span {
         Span::Fallback(inner)
     }
 }
 
-impl fmt::Debug for Span {
+impl Debug for Span {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            Span::Compiler(s) => s.fmt(f),
-            Span::Fallback(s) => s.fmt(f),
+            Span::Compiler(s) => Debug::fmt(s, f),
+            Span::Fallback(s) => Debug::fmt(s, f),
         }
     }
 }
 
-pub fn debug_span_field_if_nontrivial(debug: &mut fmt::DebugStruct, span: Span) {
+pub(crate) fn debug_span_field_if_nontrivial(debug: &mut fmt::DebugStruct, span: Span) {
     match span {
         Span::Compiler(s) => {
             debug.field("span", &s);
         }
         Span::Fallback(s) => fallback::debug_span_field_if_nontrivial(debug, s),
     }
 }
 
 #[derive(Clone)]
-pub enum Group {
+pub(crate) enum Group {
     Compiler(proc_macro::Group),
     Fallback(fallback::Group),
 }
 
 impl Group {
     pub fn new(delimiter: Delimiter, stream: TokenStream) -> Group {
         match stream {
             TokenStream::Compiler(tts) => {
@@ -647,36 +621,36 @@ impl Group {
 }
 
 impl From<fallback::Group> for Group {
     fn from(g: fallback::Group) -> Self {
         Group::Fallback(g)
     }
 }
 
-impl fmt::Display for Group {
+impl Display for Group {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            Group::Compiler(group) => group.fmt(formatter),
-            Group::Fallback(group) => group.fmt(formatter),
+            Group::Compiler(group) => Display::fmt(group, formatter),
+            Group::Fallback(group) => Display::fmt(group, formatter),
         }
     }
 }
 
-impl fmt::Debug for Group {
+impl Debug for Group {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            Group::Compiler(group) => group.fmt(formatter),
-            Group::Fallback(group) => group.fmt(formatter),
+            Group::Compiler(group) => Debug::fmt(group, formatter),
+            Group::Fallback(group) => Debug::fmt(group, formatter),
         }
     }
 }
 
 #[derive(Clone)]
-pub enum Ident {
+pub(crate) enum Ident {
     Compiler(proc_macro::Ident),
     Fallback(fallback::Ident),
 }
 
 impl Ident {
     pub fn new(string: &str, span: Span) -> Ident {
         match span {
             Span::Compiler(s) => Ident::Compiler(proc_macro::Ident::new(string, s)),
@@ -742,56 +716,56 @@ where
         let other = other.as_ref();
         match self {
             Ident::Compiler(t) => t.to_string() == other,
             Ident::Fallback(t) => t == other,
         }
     }
 }
 
-impl fmt::Display for Ident {
+impl Display for Ident {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            Ident::Compiler(t) => t.fmt(f),
-            Ident::Fallback(t) => t.fmt(f),
+            Ident::Compiler(t) => Display::fmt(t, f),
+            Ident::Fallback(t) => Display::fmt(t, f),
         }
     }
 }
 
-impl fmt::Debug for Ident {
+impl Debug for Ident {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            Ident::Compiler(t) => t.fmt(f),
-            Ident::Fallback(t) => t.fmt(f),
+            Ident::Compiler(t) => Debug::fmt(t, f),
+            Ident::Fallback(t) => Debug::fmt(t, f),
         }
     }
 }
 
 #[derive(Clone)]
-pub enum Literal {
+pub(crate) enum Literal {
     Compiler(proc_macro::Literal),
     Fallback(fallback::Literal),
 }
 
 macro_rules! suffixed_numbers {
     ($($name:ident => $kind:ident,)*) => ($(
         pub fn $name(n: $kind) -> Literal {
-            if nightly_works() {
+            if inside_proc_macro() {
                 Literal::Compiler(proc_macro::Literal::$name(n))
             } else {
                 Literal::Fallback(fallback::Literal::$name(n))
             }
         }
     )*)
 }
 
 macro_rules! unsuffixed_integers {
     ($($name:ident => $kind:ident,)*) => ($(
         pub fn $name(n: $kind) -> Literal {
-            if nightly_works() {
+            if inside_proc_macro() {
                 Literal::Compiler(proc_macro::Literal::$name(n))
             } else {
                 Literal::Fallback(fallback::Literal::$name(n))
             }
         }
     )*)
 }
 
@@ -825,49 +799,49 @@ impl Literal {
         i16_unsuffixed => i16,
         i32_unsuffixed => i32,
         i64_unsuffixed => i64,
         i128_unsuffixed => i128,
         isize_unsuffixed => isize,
     }
 
     pub fn f32_unsuffixed(f: f32) -> Literal {
-        if nightly_works() {
+        if inside_proc_macro() {
             Literal::Compiler(proc_macro::Literal::f32_unsuffixed(f))
         } else {
             Literal::Fallback(fallback::Literal::f32_unsuffixed(f))
         }
     }
 
     pub fn f64_unsuffixed(f: f64) -> Literal {
-        if nightly_works() {
+        if inside_proc_macro() {
             Literal::Compiler(proc_macro::Literal::f64_unsuffixed(f))
         } else {
             Literal::Fallback(fallback::Literal::f64_unsuffixed(f))
         }
     }
 
     pub fn string(t: &str) -> Literal {
-        if nightly_works() {
+        if inside_proc_macro() {
             Literal::Compiler(proc_macro::Literal::string(t))
         } else {
             Literal::Fallback(fallback::Literal::string(t))
         }
     }
 
     pub fn character(t: char) -> Literal {
-        if nightly_works() {
+        if inside_proc_macro() {
             Literal::Compiler(proc_macro::Literal::character(t))
         } else {
             Literal::Fallback(fallback::Literal::character(t))
         }
     }
 
     pub fn byte_string(bytes: &[u8]) -> Literal {
-        if nightly_works() {
+        if inside_proc_macro() {
             Literal::Compiler(proc_macro::Literal::byte_string(bytes))
         } else {
             Literal::Fallback(fallback::Literal::byte_string(bytes))
         }
     }
 
     pub fn span(&self) -> Span {
         match self {
@@ -903,25 +877,25 @@ impl Literal {
 }
 
 impl From<fallback::Literal> for Literal {
     fn from(s: fallback::Literal) -> Literal {
         Literal::Fallback(s)
     }
 }
 
-impl fmt::Display for Literal {
+impl Display for Literal {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            Literal::Compiler(t) => t.fmt(f),
-            Literal::Fallback(t) => t.fmt(f),
+            Literal::Compiler(t) => Display::fmt(t, f),
+            Literal::Fallback(t) => Display::fmt(t, f),
         }
     }
 }
 
-impl fmt::Debug for Literal {
+impl Debug for Literal {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            Literal::Compiler(t) => t.fmt(f),
-            Literal::Fallback(t) => t.fmt(f),
+            Literal::Compiler(t) => Debug::fmt(t, f),
+            Literal::Fallback(t) => Debug::fmt(t, f),
         }
     }
 }
diff --git a/third_party/rust/proc-macro2/tests/comments.rs b/third_party/rust/proc-macro2/tests/comments.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/proc-macro2/tests/comments.rs
@@ -0,0 +1,103 @@
+use proc_macro2::{Delimiter, Literal, Spacing, TokenStream, TokenTree};
+
+// #[doc = "..."] -> "..."
+fn lit_of_outer_doc_comment(tokens: TokenStream) -> Literal {
+    lit_of_doc_comment(tokens, false)
+}
+
+// #![doc = "..."] -> "..."
+fn lit_of_inner_doc_comment(tokens: TokenStream) -> Literal {
+    lit_of_doc_comment(tokens, true)
+}
+
+fn lit_of_doc_comment(tokens: TokenStream, inner: bool) -> Literal {
+    let mut iter = tokens.clone().into_iter();
+    match iter.next().unwrap() {
+        TokenTree::Punct(punct) => {
+            assert_eq!(punct.as_char(), '#');
+            assert_eq!(punct.spacing(), Spacing::Alone);
+        }
+        _ => panic!("wrong token {:?}", tokens),
+    }
+    if inner {
+        match iter.next().unwrap() {
+            TokenTree::Punct(punct) => {
+                assert_eq!(punct.as_char(), '!');
+                assert_eq!(punct.spacing(), Spacing::Alone);
+            }
+            _ => panic!("wrong token {:?}", tokens),
+        }
+    }
+    iter = match iter.next().unwrap() {
+        TokenTree::Group(group) => {
+            assert_eq!(group.delimiter(), Delimiter::Bracket);
+            assert!(iter.next().is_none(), "unexpected token {:?}", tokens);
+            group.stream().into_iter()
+        }
+        _ => panic!("wrong token {:?}", tokens),
+    };
+    match iter.next().unwrap() {
+        TokenTree::Ident(ident) => assert_eq!(ident.to_string(), "doc"),
+        _ => panic!("wrong token {:?}", tokens),
+    }
+    match iter.next().unwrap() {
+        TokenTree::Punct(punct) => {
+            assert_eq!(punct.as_char(), '=');
+            assert_eq!(punct.spacing(), Spacing::Alone);
+        }
+        _ => panic!("wrong token {:?}", tokens),
+    }
+    match iter.next().unwrap() {
+        TokenTree::Literal(literal) => {
+            assert!(iter.next().is_none(), "unexpected token {:?}", tokens);
+            literal
+        }
+        _ => panic!("wrong token {:?}", tokens),
+    }
+}
+
+#[test]
+fn closed_immediately() {
+    let stream = "/**/".parse::<TokenStream>().unwrap();
+    let tokens = stream.into_iter().collect::<Vec<_>>();
+    assert!(tokens.is_empty(), "not empty -- {:?}", tokens);
+}
+
+#[test]
+fn incomplete() {
+    assert!("/*/".parse::<TokenStream>().is_err());
+}
+
+#[test]
+fn lit() {
+    let stream = "/// doc".parse::<TokenStream>().unwrap();
+    let lit = lit_of_outer_doc_comment(stream);
+    assert_eq!(lit.to_string(), "\" doc\"");
+
+    let stream = "//! doc".parse::<TokenStream>().unwrap();
+    let lit = lit_of_inner_doc_comment(stream);
+    assert_eq!(lit.to_string(), "\" doc\"");
+
+    let stream = "/** doc */".parse::<TokenStream>().unwrap();
+    let lit = lit_of_outer_doc_comment(stream);
+    assert_eq!(lit.to_string(), "\" doc \"");
+
+    let stream = "/*! doc */".parse::<TokenStream>().unwrap();
+    let lit = lit_of_inner_doc_comment(stream);
+    assert_eq!(lit.to_string(), "\" doc \"");
+}
+
+#[test]
+fn carriage_return() {
+    let stream = "///\r\n".parse::<TokenStream>().unwrap();
+    let lit = lit_of_outer_doc_comment(stream);
+    assert_eq!(lit.to_string(), "\"\"");
+
+    let stream = "/**\r\n*/".parse::<TokenStream>().unwrap();
+    let lit = lit_of_outer_doc_comment(stream);
+    assert_eq!(lit.to_string(), "\"\\r\\n\"");
+
+    "///\r".parse::<TokenStream>().unwrap_err();
+    "///\r \n".parse::<TokenStream>().unwrap_err();
+    "/**\r \n*/".parse::<TokenStream>().unwrap_err();
+}
diff --git a/third_party/rust/proc-macro2/tests/test.rs b/third_party/rust/proc-macro2/tests/test.rs
--- a/third_party/rust/proc-macro2/tests/test.rs
+++ b/third_party/rust/proc-macro2/tests/test.rs
@@ -1,12 +1,11 @@
+use proc_macro2::{Ident, Literal, Spacing, Span, TokenStream, TokenTree};
 use std::str::{self, FromStr};
 
-use proc_macro2::{Ident, Literal, Spacing, Span, TokenStream, TokenTree};
-
 #[test]
 fn idents() {
     assert_eq!(
         Ident::new("String", Span::call_site()).to_string(),
         "String"
     );
     assert_eq!(Ident::new("fn", Span::call_site()).to_string(), "fn");
     assert_eq!(Ident::new("_", Span::call_site()).to_string(), "_");
@@ -105,16 +104,43 @@ fn literal_suffix() {
     assert_eq!(token_count("999u256"), 1);
     assert_eq!(token_count("999r#u256"), 3);
     assert_eq!(token_count("1."), 1);
     assert_eq!(token_count("1.f32"), 3);
     assert_eq!(token_count("1.0_0"), 1);
     assert_eq!(token_count("1._0"), 3);
     assert_eq!(token_count("1._m"), 3);
     assert_eq!(token_count("\"\"s"), 1);
+    assert_eq!(token_count("r\"\"r"), 1);
+    assert_eq!(token_count("b\"\"b"), 1);
+    assert_eq!(token_count("br\"\"br"), 1);
+    assert_eq!(token_count("r#\"\"#r"), 1);
+    assert_eq!(token_count("'c'c"), 1);
+    assert_eq!(token_count("b'b'b"), 1);
+}
+
+#[test]
+fn literal_iter_negative() {
+    let negative_literal = Literal::i32_suffixed(-3);
+    let tokens = TokenStream::from(TokenTree::Literal(negative_literal));
+    let mut iter = tokens.into_iter();
+    match iter.next().unwrap() {
+        TokenTree::Punct(punct) => {
+            assert_eq!(punct.as_char(), '-');
+            assert_eq!(punct.spacing(), Spacing::Alone);
+        }
+        unexpected => panic!("unexpected token {:?}", unexpected),
+    }
+    match iter.next().unwrap() {
+        TokenTree::Literal(literal) => {
+            assert_eq!(literal.to_string(), "3i32");
+        }
+        unexpected => panic!("unexpected token {:?}", unexpected),
+    }
+    assert!(iter.next().is_none());
 }
 
 #[test]
 fn roundtrip() {
     fn roundtrip(p: &str) {
         println!("parse: {}", p);
         let s = p.parse::<TokenStream>().unwrap().to_string();
         println!("first: {}", s);
@@ -161,46 +187,16 @@ fn fail() {
     fail("' static");
     fail("r#1");
     fail("r#_");
 }
 
 #[cfg(span_locations)]
 #[test]
 fn span_test() {
-    use proc_macro2::TokenTree;
-
-    fn check_spans(p: &str, mut lines: &[(usize, usize, usize, usize)]) {
-        let ts = p.parse::<TokenStream>().unwrap();
-        check_spans_internal(ts, &mut lines);
-    }
-
-    fn check_spans_internal(ts: TokenStream, lines: &mut &[(usize, usize, usize, usize)]) {
-        for i in ts {
-            if let Some((&(sline, scol, eline, ecol), rest)) = lines.split_first() {
-                *lines = rest;
-
-                let start = i.span().start();
-                assert_eq!(start.line, sline, "sline did not match for {}", i);
-                assert_eq!(start.column, scol, "scol did not match for {}", i);
-
-                let end = i.span().end();
-                assert_eq!(end.line, eline, "eline did not match for {}", i);
-                assert_eq!(end.column, ecol, "ecol did not match for {}", i);
-
-                match i {
-                    TokenTree::Group(ref g) => {
-                        check_spans_internal(g.stream().clone(), lines);
-                    }
-                    _ => {}
-                }
-            }
-        }
-    }
-
     check_spans(
         "\
 /// This is a document comment
 testing 123
 {
   testing 234
 }",
         &[
@@ -269,59 +265,17 @@ fn span_join() {
         joined1.unwrap().source_file(),
         source1[0].span().source_file()
     );
 }
 
 #[test]
 fn no_panic() {
     let s = str::from_utf8(b"b\'\xc2\x86  \x00\x00\x00^\"").unwrap();
-    assert!(s.parse::<proc_macro2::TokenStream>().is_err());
-}
-
-#[test]
-fn tricky_doc_comment() {
-    let stream = "/**/".parse::<proc_macro2::TokenStream>().unwrap();
-    let tokens = stream.into_iter().collect::<Vec<_>>();
-    assert!(tokens.is_empty(), "not empty -- {:?}", tokens);
-
-    let stream = "/// doc".parse::<proc_macro2::TokenStream>().unwrap();
-    let tokens = stream.into_iter().collect::<Vec<_>>();
-    assert!(tokens.len() == 2, "not length 2 -- {:?}", tokens);
-    match tokens[0] {
-        proc_macro2::TokenTree::Punct(ref tt) => assert_eq!(tt.as_char(), '#'),
-        _ => panic!("wrong token {:?}", tokens[0]),
-    }
-    let mut tokens = match tokens[1] {
-        proc_macro2::TokenTree::Group(ref tt) => {
-            assert_eq!(tt.delimiter(), proc_macro2::Delimiter::Bracket);
-            tt.stream().into_iter()
-        }
-        _ => panic!("wrong token {:?}", tokens[0]),
-    };
-
-    match tokens.next().unwrap() {
-        proc_macro2::TokenTree::Ident(ref tt) => assert_eq!(tt.to_string(), "doc"),
-        t => panic!("wrong token {:?}", t),
-    }
-    match tokens.next().unwrap() {
-        proc_macro2::TokenTree::Punct(ref tt) => assert_eq!(tt.as_char(), '='),
-        t => panic!("wrong token {:?}", t),
-    }
-    match tokens.next().unwrap() {
-        proc_macro2::TokenTree::Literal(ref tt) => {
-            assert_eq!(tt.to_string(), "\" doc\"");
-        }
-        t => panic!("wrong token {:?}", t),
-    }
-    assert!(tokens.next().is_none());
-
-    let stream = "//! doc".parse::<proc_macro2::TokenStream>().unwrap();
-    let tokens = stream.into_iter().collect::<Vec<_>>();
-    assert!(tokens.len() == 3, "not length 3 -- {:?}", tokens);
+    assert!(s.parse::<TokenStream>().is_err());
 }
 
 #[test]
 fn op_before_comment() {
     let mut tts = TokenStream::from_str("~// comment").unwrap().into_iter();
     match tts.next().unwrap() {
         TokenTree::Punct(tt) => {
             assert_eq!(tt.as_char(), '~');
@@ -340,30 +294,30 @@ fn raw_identifier() {
     }
     assert!(tts.next().is_none());
 }
 
 #[test]
 fn test_debug_ident() {
     let ident = Ident::new("proc_macro", Span::call_site());
 
-    #[cfg(not(procmacro2_semver_exempt))]
+    #[cfg(not(span_locations))]
     let expected = "Ident(proc_macro)";
 
-    #[cfg(procmacro2_semver_exempt)]
-    let expected = "Ident { sym: proc_macro, span: bytes(0..0) }";
+    #[cfg(span_locations)]
+    let expected = "Ident { sym: proc_macro }";
 
     assert_eq!(expected, format!("{:?}", ident));
 }
 
 #[test]
 fn test_debug_tokenstream() {
     let tts = TokenStream::from_str("[a + 1]").unwrap();
 
-    #[cfg(not(procmacro2_semver_exempt))]
+    #[cfg(not(span_locations))]
     let expected = "\
 TokenStream [
     Group {
         delimiter: Bracket,
         stream: TokenStream [
             Ident {
                 sym: a,
             },
@@ -374,17 +328,17 @@ TokenStream [
             Literal {
                 lit: 1,
             },
         ],
     },
 ]\
     ";
 
-    #[cfg(not(procmacro2_semver_exempt))]
+    #[cfg(not(span_locations))]
     let expected_before_trailing_commas = "\
 TokenStream [
     Group {
         delimiter: Bracket,
         stream: TokenStream [
             Ident {
                 sym: a
             },
@@ -395,17 +349,17 @@ TokenStream [
             Literal {
                 lit: 1
             }
         ]
     }
 ]\
     ";
 
-    #[cfg(procmacro2_semver_exempt)]
+    #[cfg(span_locations)]
     let expected = "\
 TokenStream [
     Group {
         delimiter: Bracket,
         stream: TokenStream [
             Ident {
                 sym: a,
                 span: bytes(2..3),
@@ -420,17 +374,17 @@ TokenStream [
                 span: bytes(6..7),
             },
         ],
         span: bytes(1..8),
     },
 ]\
     ";
 
-    #[cfg(procmacro2_semver_exempt)]
+    #[cfg(span_locations)]
     let expected_before_trailing_commas = "\
 TokenStream [
     Group {
         delimiter: Bracket,
         stream: TokenStream [
             Ident {
                 sym: a,
                 span: bytes(2..3)
@@ -459,8 +413,85 @@ TokenStream [
 }
 
 #[test]
 fn default_tokenstream_is_empty() {
     let default_token_stream: TokenStream = Default::default();
 
     assert!(default_token_stream.is_empty());
 }
+
+#[test]
+fn tuple_indexing() {
+    // This behavior may change depending on https://github.com/rust-lang/rust/pull/71322
+    let mut tokens = "tuple.0.0".parse::<TokenStream>().unwrap().into_iter();
+    assert_eq!("tuple", tokens.next().unwrap().to_string());
+    assert_eq!(".", tokens.next().unwrap().to_string());
+    assert_eq!("0.0", tokens.next().unwrap().to_string());
+    assert!(tokens.next().is_none());
+}
+
+#[cfg(span_locations)]
+#[test]
+fn non_ascii_tokens() {
+    check_spans("// abc", &[]);
+    check_spans("// ábc", &[]);
+    check_spans("// abc x", &[]);
+    check_spans("// ábc x", &[]);
+    check_spans("/* abc */ x", &[(1, 10, 1, 11)]);
+    check_spans("/* ábc */ x", &[(1, 10, 1, 11)]);
+    check_spans("/* ab\nc */ x", &[(2, 5, 2, 6)]);
+    check_spans("/* áb\nc */ x", &[(2, 5, 2, 6)]);
+    check_spans("/*** abc */ x", &[(1, 12, 1, 13)]);
+    check_spans("/*** ábc */ x", &[(1, 12, 1, 13)]);
+    check_spans(r#""abc""#, &[(1, 0, 1, 5)]);
+    check_spans(r#""ábc""#, &[(1, 0, 1, 5)]);
+    check_spans(r###"r#"abc"#"###, &[(1, 0, 1, 8)]);
+    check_spans(r###"r#"ábc"#"###, &[(1, 0, 1, 8)]);
+    check_spans("r#\"a\nc\"#", &[(1, 0, 2, 3)]);
+    check_spans("r#\"á\nc\"#", &[(1, 0, 2, 3)]);
+    check_spans("'a'", &[(1, 0, 1, 3)]);
+    check_spans("'á'", &[(1, 0, 1, 3)]);
+    check_spans("//! abc", &[(1, 0, 1, 7), (1, 0, 1, 7), (1, 0, 1, 7)]);
+    check_spans("//! ábc", &[(1, 0, 1, 7), (1, 0, 1, 7), (1, 0, 1, 7)]);
+    check_spans("//! abc\n", &[(1, 0, 1, 7), (1, 0, 1, 7), (1, 0, 1, 7)]);
+    check_spans("//! ábc\n", &[(1, 0, 1, 7), (1, 0, 1, 7), (1, 0, 1, 7)]);
+    check_spans("/*! abc */", &[(1, 0, 1, 10), (1, 0, 1, 10), (1, 0, 1, 10)]);
+    check_spans("/*! ábc */", &[(1, 0, 1, 10), (1, 0, 1, 10), (1, 0, 1, 10)]);
+    check_spans("/*! a\nc */", &[(1, 0, 2, 4), (1, 0, 2, 4), (1, 0, 2, 4)]);
+    check_spans("/*! á\nc */", &[(1, 0, 2, 4), (1, 0, 2, 4), (1, 0, 2, 4)]);
+    check_spans("abc", &[(1, 0, 1, 3)]);
+    check_spans("ábc", &[(1, 0, 1, 3)]);
+    check_spans("ábć", &[(1, 0, 1, 3)]);
+    check_spans("abc// foo", &[(1, 0, 1, 3)]);
+    check_spans("ábc// foo", &[(1, 0, 1, 3)]);
+    check_spans("ábć// foo", &[(1, 0, 1, 3)]);
+    check_spans("b\"a\\\n c\"", &[(1, 0, 2, 3)]);
+    check_spans("b\"a\\\n\u{00a0}c\"", &[(1, 0, 2, 3)]);
+}
+
+#[cfg(span_locations)]
+fn check_spans(p: &str, mut lines: &[(usize, usize, usize, usize)]) {
+    let ts = p.parse::<TokenStream>().unwrap();
+    check_spans_internal(ts, &mut lines);
+    assert!(lines.is_empty(), "leftover ranges: {:?}", lines);
+}
+
+#[cfg(span_locations)]
+fn check_spans_internal(ts: TokenStream, lines: &mut &[(usize, usize, usize, usize)]) {
+    for i in ts {
+        if let Some((&(sline, scol, eline, ecol), rest)) = lines.split_first() {
+            *lines = rest;
+
+            let start = i.span().start();
+            assert_eq!(start.line, sline, "sline did not match for {}", i);
+            assert_eq!(start.column, scol, "scol did not match for {}", i);
+
+            let end = i.span().end();
+            assert_eq!(end.line, eline, "eline did not match for {}", i);
+            assert_eq!(end.column, ecol, "ecol did not match for {}", i);
+
+            if let TokenTree::Group(g) = i {
+                check_spans_internal(g.stream().clone(), lines);
+            }
+        }
+    }
+}
diff --git a/third_party/rust/proc-macro2/tests/test_fmt.rs b/third_party/rust/proc-macro2/tests/test_fmt.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/proc-macro2/tests/test_fmt.rs
@@ -0,0 +1,26 @@
+use proc_macro2::{Delimiter, Group, Ident, Span, TokenStream, TokenTree};
+use std::iter::{self, FromIterator};
+
+#[test]
+fn test_fmt_group() {
+    let ident = Ident::new("x", Span::call_site());
+    let inner = TokenStream::from_iter(iter::once(TokenTree::Ident(ident)));
+    let parens_empty = Group::new(Delimiter::Parenthesis, TokenStream::new());
+    let parens_nonempty = Group::new(Delimiter::Parenthesis, inner.clone());
+    let brackets_empty = Group::new(Delimiter::Bracket, TokenStream::new());
+    let brackets_nonempty = Group::new(Delimiter::Bracket, inner.clone());
+    let braces_empty = Group::new(Delimiter::Brace, TokenStream::new());
+    let braces_nonempty = Group::new(Delimiter::Brace, inner.clone());
+    let none_empty = Group::new(Delimiter::None, TokenStream::new());
+    let none_nonempty = Group::new(Delimiter::None, inner.clone());
+
+    // Matches libproc_macro.
+    assert_eq!("()", parens_empty.to_string());
+    assert_eq!("(x)", parens_nonempty.to_string());
+    assert_eq!("[]", brackets_empty.to_string());
+    assert_eq!("[x]", brackets_nonempty.to_string());
+    assert_eq!("{ }", braces_empty.to_string());
+    assert_eq!("{ x }", braces_nonempty.to_string());
+    assert_eq!("", none_empty.to_string());
+    assert_eq!("x", none_nonempty.to_string());
+}
diff --git a/third_party/rust/syn/.cargo-checksum.json b/third_party/rust/syn/.cargo-checksum.json
--- a/third_party/rust/syn/.cargo-checksum.json
+++ b/third_party/rust/syn/.cargo-checksum.json
@@ -1,1 +1,1 @@
-{"files":{"Cargo.toml":"484d29864d333a361652fa4e24e1dcfab9efa47705ffd8c106d802eb03b78da7","LICENSE-APACHE":"a60eea817514531668d7e00765731449fe14d059d3249e0bc93b36de45f759f2","LICENSE-MIT":"23f18e03dc49df91622fe2a76176497404e46ced8a715d9d2b67a7446571cca3","README.md":"ca605417b6db8c995458f8407afaad6c177aedcc2274004283600f5638fa1b0c","benches/file.rs":"b45211cc4a0296a77aac2b4de16dbc6b5cb66adfb5afac00a77bccea87f43968","benches/rust.rs":"9cc0f62e944f1583d05c43a395a1556731501cf5976ef67a081f4f6387f883ba","build.rs":"7423ab199728d55c7d64c44b7c6729cfd93bd8273366a77707353003e27565d7","src/attr.rs":"cf81add298f0e75c35a9980a59bc3c2fd3fe933635830d1591374eeb2487c225","src/await.rs":"18f0b2ecb319991f891e300011424985e3cf33d166ea9f29f22d575fc8c83a76","src/bigint.rs":"efc7f64959980653d73fe4f8bc2a3a2904dc05f45b02c6dc15cd316fa3d7c338","src/buffer.rs":"2a432c11a3da67a21d46c2272bf9ce60a0bb20893b5750027bbd8ca3e843ab35","src/custom_keyword.rs":"589e46ec1be9a04d6de12c0b8cadf87cc1c05606ed46ddea62e9869cbca4a191","src/custom_punctuation.rs":"2ba2e294e15a0fce7ede3686c42b2891797079a724dd1193b66e7d305624c891","src/data.rs":"cc9b250d084e444782d3ff5e63c1ba387cbde8f7f2e977eab9846d920b4b8c3f","src/derive.rs":"c18878f14be5d5ab11fd7dda2d2ff1ff75c9662daf11eed033de62e4d0670a89","src/discouraged.rs":"50e10915695c4d14f64a78e20ecbef90a2cd53a7c26ee3426a2524a8ee5c9cbf","src/error.rs":"2c17a402f83ed5ae4ad96e753216771bef620235c2ff1ccc23f4bbafc7266fe1","src/export.rs":"dcae67456278c0339acfbcbb4737b8d37cfba5a150ae789f31f4be79abf7e726","src/expr.rs":"871d8eeb43cef02ef88de3bea7477b79b4eabc096a0899dde0e5750edf482f49","src/ext.rs":"b97ed549490b9248b5b5df31b3d5b08ba8791e23e6c5d3a1157a0363eb683ff3","src/file.rs":"3cc2bf5c709238d515a557f721f231c8c725b196400de051f945b549299d38a7","src/gen/fold.rs":"10b3ae33d0ce410d6bbe8b93be9d5f9e856c7dc8212133cc46b703f97d548190","src/gen/visit.rs":"e0f5798552d186024696b7bfc7219d4ff53b0e45f735a83e77cbb6b6578c5fa4","src/gen/visit_mut.rs":"9f7dda83907969971dba84d545aaa563b0728e54db97ffab5050fdf43a79c731","src/gen_helper.rs":"ea6c66388365971db6a2fc86cbb208f7eacde77e245bc8623f27a3642a3d7741","src/generics.rs":"d845d7a828863123a5187fd0fe59c9dae3636f63bad302bd035792eed3dcb1ba","src/group.rs":"119b62d8481b4b1c327639bed40e114bf1969765250b68186628247fd4144b3b","src/ident.rs":"503156ce51a7ef0420892e8dbf2ecf8fe51f42a84d52cc2c05654e1a83020cbf","src/item.rs":"213f2f58c65ee1aa222f111bc9b1be681f8fb069caed04ca56586839979318d0","src/keyword.rs":"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855","src/lib.rs":"24778e9f15e8025e75aca114c712716ada586b471adb3b3b69278f4d39b8a21b","src/lifetime.rs":"905359708f772ec858954badde69ee016d29e6eeba1dd205b268445b1aff6f3a","src/lit.rs":"5bb0bddb94cbd256e50e92dc091a0baa09f1be40a77058b897507f3b17191e5d","src/lookahead.rs":"5cce8b4cb345a85c24a452ea6d78eadb76f01ca0a789cbf5ce35108334904173","src/mac.rs":"6b468244cc07e3f2f10419f833d9e2ed23edbcd6dc34cf21c5947633699db964","src/macros.rs":"0d8c3bab47539aa2d00bec64e92c901ea2c9c0af74c868051c0905b82650f970","src/op.rs":"93cd44770bb110deadf807a01d9a666efe644b6e3010f4b51cae77ee7438cfbb","src/parse.rs":"5017123c249ebc65866af113a0ad671814b9873f47568180e6539a305eb0317d","src/parse_macro_input.rs":"f799aadb7216c2d333b579f48ed2fedfe07b5e96f004b25b569649ffbaa958d2","src/parse_quote.rs":"81575bf60b18b0d8624d7025a5bcc8dcd6633ad70c454dee2a06e4c391700b6c","src/pat.rs":"db0f2263b9813de1f4e3e3e0396fe0080b1e11c8090c6b4fb6fca3cfbe22bc96","src/path.rs":"32e685ac7fd2d4b9989802de8f326a8d47fa710f86ec3e45fd9d3ff8fdfe97ef","src/print.rs":"da6529c1d9d21aaf6c835f66b4e67eacb7cf91a10eb5e9a2143b49bf99b3b5e1","src/punctuated.rs":"384e7b317b26f24118eb4b0c39e949ee9f4f3e700a4c80e462342c83b2cc3282","src/sealed.rs":"896a495a5340eec898527f18bd4ddca408ea03ea0ee3af30074ff48deace778d","src/span.rs":"748c51c6feb223c26d3b1701f5bb98aee823666c775c98106cfa24fe29d8cec1","src/spanned.rs":"adddb6acae14a0fa340df302b932c31e34b259706ce56fd82ab597ec424500e1","src/stmt.rs":"fbccf2b4da7980fe6ea8d99457d291577c0f225b370c1dd97da41abf2a18fcf7","src/thread.rs":"815eca6bd64f4eef7c447f0809e84108f5428ff50225224b373efd8fbb696874","src/token.rs":"761d8d1793560eb2b631c36ddfdbb14ac65178405f095453aa0e75e8816bdbb9","src/tt.rs":"1e32ae216d14d895ff621bf32bc611f138aa00108b0090be2cbaa0affebe8e2a","src/ty.rs":"ce052e0079b65b66bea4e9502d2ff2c90ad4b867904bf7eb892eb60aa3ef219a","tests/clone.sh":"961243d42540d9992090efbbd5478b7aa395671db64a6c28cdadb6edc610ebdf","tests/common/eq.rs":"a42d339808fd32dd4bfd440c254add8c56d5e2cde3a6bf0c88621b618ce5eaa7","tests/common/mod.rs":"20a3300016351fa210a193fbb0db059ef5125fa7909585ded64790004d4977ed","tests/common/parse.rs":"17ba6d1e74aaa3f8096c6d379d803221f12d95cca69927be047d6ddf8367647f","tests/debug/gen.rs":"57bd5cf585e0b86ad00f29f09ff3db3390c4a756d503514a9b28407500dcea3c","tests/debug/mod.rs":"462d6fe34ee75c3ca1207d4db2ff3bdee5b430b9f9ca632e5671d1588d3f76b3","tests/features/error.rs":"e0581a2869cbd237c2bc18a0a85272296e1577bb5f7317a67fa85e28e04eea6f","tests/features/mod.rs":"66a2605ec54ede29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\ No newline at end of file
diff --git a/third_party/rust/syn/Cargo.toml b/third_party/rust/syn/Cargo.toml
--- a/third_party/rust/syn/Cargo.toml
+++ b/third_party/rust/syn/Cargo.toml
@@ -8,79 +8,90 @@
 # If you believe there's an error in this file please file an
 # issue against the rust-lang/cargo repository. If you're
 # editing this file be aware that the upstream Cargo.toml
 # will likely look very different (and much more reasonable)
 
 [package]
 edition = "2018"
 name = "syn"
-version = "1.0.5"
+version = "1.0.40"
 authors = ["David Tolnay <dtolnay@gmail.com>"]
 include = ["/benches/**", "/build.rs", "/Cargo.toml", "/LICENSE-APACHE", "/LICENSE-MIT", "/README.md", "/src/**", "/tests/**"]
 description = "Parser for Rust source code"
 documentation = "https://docs.rs/syn"
 readme = "README.md"
 categories = ["development-tools::procedural-macro-helpers"]
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/dtolnay/syn"
 [package.metadata.docs.rs]
 all-features = true
+targets = ["x86_64-unknown-linux-gnu"]
 
 [package.metadata.playground]
-all-features = true
-
-[lib]
-name = "syn"
+features = ["full", "visit", "visit-mut", "fold", "extra-traits"]
 
 [[bench]]
 name = "rust"
 harness = false
 required-features = ["full", "parsing"]
-edition = "2018"
 
 [[bench]]
 name = "file"
 required-features = ["full", "parsing"]
-edition = "2018"
 [dependencies.proc-macro2]
-version = "1.0"
+version = "1.0.13"
 default-features = false
 
 [dependencies.quote]
 version = "1.0"
 optional = true
 default-features = false
 
 [dependencies.unicode-xid]
 version = "0.2"
+[dev-dependencies.anyhow]
+version = "1.0"
+
+[dev-dependencies.flate2]
+version = "1.0"
+
 [dev-dependencies.insta]
-version = "0.9"
+version = "0.16"
 
 [dev-dependencies.rayon]
 version = "1.0"
 
 [dev-dependencies.ref-cast]
-version = "0.2"
+version = "1.0"
 
 [dev-dependencies.regex]
 version = "1.0"
 
+[dev-dependencies.reqwest]
+version = "0.10"
+features = ["blocking"]
+
+[dev-dependencies.syn-test-suite]
+version = "0"
+
+[dev-dependencies.tar]
+version = "0.4"
+
 [dev-dependencies.termcolor]
 version = "1.0"
 
 [dev-dependencies.walkdir]
 version = "2.1"
 
 [features]
 clone-impls = []
 default = ["derive", "parsing", "printing", "clone-impls", "proc-macro"]
 derive = []
 extra-traits = []
 fold = []
 full = []
 parsing = []
 printing = ["quote"]
 proc-macro = ["proc-macro2/proc-macro", "quote/proc-macro"]
+test = ["syn-test-suite/all-features"]
 visit = []
 visit-mut = []
-[badges.travis-ci]
-repository = "dtolnay/syn"
diff --git a/third_party/rust/syn/README.md b/third_party/rust/syn/README.md
--- a/third_party/rust/syn/README.md
+++ b/third_party/rust/syn/README.md
@@ -1,15 +1,15 @@
 Parser for Rust source code
 ===========================
 
-[![Build Status](https://api.travis-ci.org/dtolnay/syn.svg?branch=master)](https://travis-ci.org/dtolnay/syn)
-[![Latest Version](https://img.shields.io/crates/v/syn.svg)](https://crates.io/crates/syn)
-[![Rust Documentation](https://img.shields.io/badge/api-rustdoc-blue.svg)](https://docs.rs/syn/1.0/syn/)
-[![Rustc Version 1.31+](https://img.shields.io/badge/rustc-1.31+-lightgray.svg)](https://blog.rust-lang.org/2018/12/06/Rust-1.31-and-rust-2018.html)
+[<img alt="github" src="https://img.shields.io/badge/github-dtolnay/syn-8da0cb?style=for-the-badge&labelColor=555555&logo=github" height="20">](https://github.com/dtolnay/syn)
+[<img alt="crates.io" src="https://img.shields.io/crates/v/syn.svg?style=for-the-badge&color=fc8d62&logo=rust" height="20">](https://crates.io/crates/syn)
+[<img alt="docs.rs" src="https://img.shields.io/badge/docs.rs-syn-66c2a5?style=for-the-badge&labelColor=555555&logoColor=white&logo=data:image/svg+xml;base64,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" height="20">](https://docs.rs/syn)
+[<img alt="build status" src="https://img.shields.io/github/workflow/status/dtolnay/syn/CI/master?style=for-the-badge" height="20">](https://github.com/dtolnay/syn/actions?query=branch%3Amaster)
 
 Syn is a parsing library for parsing a stream of Rust tokens into a syntax tree
 of Rust source code.
 
 Currently this library is geared toward use in Rust procedural macros, but
 contains some APIs that may be useful more generally.
 
 - **Data structures** — Syn provides a complete syntax tree that can represent
@@ -41,20 +41,16 @@ contains some APIs that may be useful mo
 
 [`syn::File`]: https://docs.rs/syn/1.0/syn/struct.File.html
 [`syn::Item`]: https://docs.rs/syn/1.0/syn/enum.Item.html
 [`syn::Expr`]: https://docs.rs/syn/1.0/syn/enum.Expr.html
 [`syn::Type`]: https://docs.rs/syn/1.0/syn/enum.Type.html
 [`syn::DeriveInput`]: https://docs.rs/syn/1.0/syn/struct.DeriveInput.html
 [parser functions]: https://docs.rs/syn/1.0/syn/parse/index.html
 
-If you get stuck with anything involving procedural macros in Rust I am happy to
-provide help even if the issue is not related to Syn. Please file a ticket in
-this repo.
-
 *Version requirement: Syn supports rustc 1.31 and up.*
 
 [*Release notes*](https://github.com/dtolnay/syn/releases)
 
 <br>
 
 ## Resources
 
@@ -83,18 +79,16 @@ tokens back to the compiler to compile i
 syn = "1.0"
 quote = "1.0"
 
 [lib]
 proc-macro = true
 ```
 
 ```rust
-extern crate proc_macro;
-
 use proc_macro::TokenStream;
 use quote::quote;
 use syn::{parse_macro_input, DeriveInput};
 
 #[proc_macro_derive(MyMacro)]
 pub fn my_macro(input: TokenStream) -> TokenStream {
     // Parse the input tokens into a syntax tree
     let input = parse_macro_input!(input as DeriveInput);
@@ -266,17 +260,17 @@ incompatible ecosystems for proc macros 
 
 In general all of your code should be written against proc-macro2 rather than
 proc-macro. The one exception is in the signatures of procedural macro entry
 points, which are required by the language to use `proc_macro::TokenStream`.
 
 The proc-macro2 crate will automatically detect and use the compiler's data
 structures when a procedural macro is active.
 
-[proc-macro2]: https://docs.rs/proc-macro2/1.0.0/proc_macro2/
+[proc-macro2]: https://docs.rs/proc-macro2/1.0/proc_macro2/
 
 <br>
 
 #### License
 
 <sup>
 Licensed under either of <a href="LICENSE-APACHE">Apache License, Version
 2.0</a> or <a href="LICENSE-MIT">MIT license</a> at your option.
diff --git a/third_party/rust/syn/benches/file.rs b/third_party/rust/syn/benches/file.rs
--- a/third_party/rust/syn/benches/file.rs
+++ b/third_party/rust/syn/benches/file.rs
@@ -1,14 +1,21 @@
 // $ cargo bench --features full --bench file
 
 #![feature(rustc_private, test)]
+#![recursion_limit = "1024"]
 
 extern crate test;
 
+#[macro_use]
+#[path = "../tests/macros/mod.rs"]
+mod macros;
+
+#[path = "../tests/common/mod.rs"]
+mod common;
 #[path = "../tests/repo/mod.rs"]
 pub mod repo;
 
 use proc_macro2::TokenStream;
 use std::fs;
 use std::str::FromStr;
 use test::Bencher;
 
diff --git a/third_party/rust/syn/benches/rust.rs b/third_party/rust/syn/benches/rust.rs
--- a/third_party/rust/syn/benches/rust.rs
+++ b/third_party/rust/syn/benches/rust.rs
@@ -1,15 +1,22 @@
 // $ cargo bench --features full --bench rust
 //
 // Syn only, useful for profiling:
 // $ RUSTFLAGS='--cfg syn_only' cargo build --release --features full --bench rust
 
 #![cfg_attr(not(syn_only), feature(rustc_private))]
+#![recursion_limit = "1024"]
 
+#[macro_use]
+#[path = "../tests/macros/mod.rs"]
+mod macros;
+
+#[path = "../tests/common/mod.rs"]
+mod common;
 #[path = "../tests/repo/mod.rs"]
 mod repo;
 
 use std::fs;
 use std::time::{Duration, Instant};
 
 #[cfg(not(syn_only))]
 mod tokenstream_parse {
@@ -23,41 +30,45 @@ mod tokenstream_parse {
 
 mod syn_parse {
     pub fn bench(content: &str) -> Result<(), ()> {
         syn::parse_file(content).map(drop).map_err(drop)
     }
 }
 
 #[cfg(not(syn_only))]
-mod libsyntax_parse {
+mod librustc_parse {
     extern crate rustc_data_structures;
-    extern crate syntax;
-    extern crate syntax_pos;
+    extern crate rustc_errors;
+    extern crate rustc_parse;
+    extern crate rustc_session;
+    extern crate rustc_span;
 
     use rustc_data_structures::sync::Lrc;
-    use syntax::edition::Edition;
-    use syntax::errors::{emitter::Emitter, DiagnosticBuilder, Handler};
-    use syntax::parse::ParseSess;
-    use syntax::source_map::{FilePathMapping, SourceMap};
-    use syntax_pos::FileName;
+    use rustc_errors::{emitter::Emitter, Diagnostic, Handler};
+    use rustc_session::parse::ParseSess;
+    use rustc_span::source_map::{FilePathMapping, SourceMap};
+    use rustc_span::{edition::Edition, FileName};
 
     pub fn bench(content: &str) -> Result<(), ()> {
         struct SilentEmitter;
 
         impl Emitter for SilentEmitter {
-            fn emit_diagnostic(&mut self, _db: &DiagnosticBuilder) {}
+            fn emit_diagnostic(&mut self, _diag: &Diagnostic) {}
+            fn source_map(&self) -> Option<&Lrc<SourceMap>> {
+                None
+            }
         }
 
-        syntax::with_globals(Edition::Edition2018, || {
+        rustc_span::with_session_globals(Edition::Edition2018, || {
             let cm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
             let emitter = Box::new(SilentEmitter);
             let handler = Handler::with_emitter(false, None, emitter);
             let sess = ParseSess::with_span_handler(handler, cm);
-            if let Err(mut diagnostic) = syntax::parse::parse_crate_from_source_str(
+            if let Err(mut diagnostic) = rustc_parse::parse_crate_from_source_str(
                 FileName::Custom("bench".to_owned()),
                 content.to_owned(),
                 &sess,
             ) {
                 diagnostic.cancel();
                 return Err(());
             };
             Ok(())
@@ -99,21 +110,21 @@ fn exec(mut codepath: impl FnMut(&str) -
     assert_eq!(success, total);
     begin.elapsed()
 }
 
 fn main() {
     repo::clone_rust();
 
     macro_rules! testcases {
-        ($($(#[$cfg:meta])* $name:path,)*) => {
+        ($($(#[$cfg:meta])* $name:ident,)*) => {
             vec![
                 $(
                     $(#[$cfg])*
-                    (stringify!($name), $name as fn(&str) -> Result<(), ()>),
+                    (stringify!($name), $name::bench as fn(&str) -> Result<(), ()>),
                 )*
             ]
         };
     }
 
     #[cfg(not(syn_only))]
     {
         let mut lines = 0;
@@ -123,22 +134,22 @@ fn main() {
             files += 1;
             Ok(())
         });
         eprintln!("\n{} lines in {} files", lines, files);
     }
 
     for (name, f) in testcases!(
         #[cfg(not(syn_only))]
-        read_from_disk::bench,
+        read_from_disk,
         #[cfg(not(syn_only))]
-        tokenstream_parse::bench,
-        syn_parse::bench,
+        tokenstream_parse,
+        syn_parse,
         #[cfg(not(syn_only))]
-        libsyntax_parse::bench,
+        librustc_parse,
     ) {
         eprint!("{:20}", format!("{}:", name));
         let elapsed = exec(f);
         eprintln!(
             "elapsed={}.{:03}s",
             elapsed.as_secs(),
             elapsed.subsec_millis(),
         );
diff --git a/third_party/rust/syn/build.rs b/third_party/rust/syn/build.rs
--- a/third_party/rust/syn/build.rs
+++ b/third_party/rust/syn/build.rs
@@ -1,11 +1,11 @@
 use std::env;
 use std::process::Command;
-use std::str::{self, FromStr};
+use std::str;
 
 // The rustc-cfg strings below are *not* public API. Please let us know by
 // opening a GitHub issue if your build environment requires some way to enable
 // these cfgs other than by executing our build script.
 fn main() {
     let compiler = match rustc_version() {
         Some(compiler) => compiler,
         None => return,
@@ -21,43 +21,19 @@ fn main() {
 }
 
 struct Compiler {
     minor: u32,
     nightly: bool,
 }
 
 fn rustc_version() -> Option<Compiler> {
-    let rustc = match env::var_os("RUSTC") {
-        Some(rustc) => rustc,
-        None => return None,
-    };
-
-    let output = match Command::new(rustc).arg("--version").output() {
-        Ok(output) => output,
-        Err(_) => return None,
-    };
-
-    let version = match str::from_utf8(&output.stdout) {
-        Ok(version) => version,
-        Err(_) => return None,
-    };
-
+    let rustc = env::var_os("RUSTC")?;
+    let output = Command::new(rustc).arg("--version").output().ok()?;
+    let version = str::from_utf8(&output.stdout).ok()?;
     let mut pieces = version.split('.');
     if pieces.next() != Some("rustc 1") {
         return None;
     }
-
-    let next = match pieces.next() {
-        Some(next) => next,
-        None => return None,
-    };
-
-    let minor = match u32::from_str(next) {
-        Ok(minor) => minor,
-        Err(_) => return None,
-    };
-
-    Some(Compiler {
-        minor: minor,
-        nightly: version.contains("nightly"),
-    })
+    let minor = pieces.next()?.parse().ok()?;
+    let nightly = version.contains("nightly");
+    Some(Compiler { minor, nightly })
 }
diff --git a/third_party/rust/syn/src/attr.rs b/third_party/rust/syn/src/attr.rs
--- a/third_party/rust/syn/src/attr.rs
+++ b/third_party/rust/syn/src/attr.rs
@@ -4,25 +4,21 @@ use crate::punctuated::Punctuated;
 use std::iter;
 
 use proc_macro2::TokenStream;
 
 #[cfg(feature = "parsing")]
 use crate::parse::{Parse, ParseBuffer, ParseStream, Parser, Result};
 #[cfg(feature = "parsing")]
 use crate::punctuated::Pair;
-#[cfg(feature = "extra-traits")]
-use crate::tt::TokenStreamHelper;
-#[cfg(feature = "extra-traits")]
-use std::hash::{Hash, Hasher};
 
 ast_struct! {
     /// An attribute like `#[repr(transparent)]`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     ///
     /// <br>
     ///
     /// # Syntax
     ///
     /// Rust has six types of attributes.
     ///
@@ -106,58 +102,69 @@ ast_struct! {
     /// If the attribute you are parsing is expected to conform to the
     /// conventional structured form of attribute, use [`parse_meta()`] to
     /// obtain that structured representation. If the attribute follows some
     /// other grammar of its own, use [`parse_args()`] to parse that into the
     /// expected data structure.
     ///
     /// [`parse_meta()`]: Attribute::parse_meta
     /// [`parse_args()`]: Attribute::parse_args
-    pub struct Attribute #manual_extra_traits {
+    ///
+    /// <p><br></p>
+    ///
+    /// # Doc comments
+    ///
+    /// The compiler transforms doc comments, such as `/// comment` and `/*!
+    /// comment */`, into attributes before macros are expanded. Each comment is
+    /// expanded into an attribute of the form `#[doc = r"comment"]`.
+    ///
+    /// As an example, the following `mod` items are expanded identically:
+    ///
+    /// ```
+    /// # use syn::{ItemMod, parse_quote};
+    /// let doc: ItemMod = parse_quote! {
+    ///     /// Single line doc comments
+    ///     /// We write so many!
+    ///     /**
+    ///      * Multi-line comments...
+    ///      * May span many lines
+    ///      */
+    ///     mod example {
+    ///         //! Of course, they can be inner too
+    ///         /*! And fit in a single line */
+    ///     }
+    /// };
+    /// let attr: ItemMod = parse_quote! {
+    ///     #[doc = r" Single line doc comments"]
+    ///     #[doc = r" We write so many!"]
+    ///     #[doc = r"
+    ///      * Multi-line comments...
+    ///      * May span many lines
+    ///      "]
+    ///     mod example {
+    ///         #![doc = r" Of course, they can be inner too"]
+    ///         #![doc = r" And fit in a single line "]
+    ///     }
+    /// };
+    /// assert_eq!(doc, attr);
+    /// ```
+    pub struct Attribute {
         pub pound_token: Token![#],
         pub style: AttrStyle,
         pub bracket_token: token::Bracket,
         pub path: Path,
         pub tokens: TokenStream,
     }
 }
 
-#[cfg(feature = "extra-traits")]
-impl Eq for Attribute {}
-
-#[cfg(feature = "extra-traits")]
-impl PartialEq for Attribute {
-    fn eq(&self, other: &Self) -> bool {
-        self.style == other.style
-            && self.pound_token == other.pound_token
-            && self.bracket_token == other.bracket_token
-            && self.path == other.path
-            && TokenStreamHelper(&self.tokens) == TokenStreamHelper(&other.tokens)
-    }
-}
-
-#[cfg(feature = "extra-traits")]
-impl Hash for Attribute {
-    fn hash<H>(&self, state: &mut H)
-    where
-        H: Hasher,
-    {
-        self.style.hash(state);
-        self.pound_token.hash(state);
-        self.bracket_token.hash(state);
-        self.path.hash(state);
-        TokenStreamHelper(&self.tokens).hash(state);
-    }
-}
-
 impl Attribute {
     /// Parses the content of the attribute, consisting of the path and tokens,
     /// as a [`Meta`] if possible.
     ///
-    /// *This function is available if Syn is built with the `"parsing"`
+    /// *This function is available only if Syn is built with the `"parsing"`
     /// feature.*
     #[cfg(feature = "parsing")]
     pub fn parse_meta(&self) -> Result<Meta> {
         fn clone_ident_segment(segment: &PathSegment) -> PathSegment {
             PathSegment {
                 ident: segment.ident.clone(),
                 arguments: PathArguments::None,
             }
@@ -194,91 +201,95 @@ impl Attribute {
     ///   parser; and
     /// - the error message has a more useful span when `tokens` is empty.
     ///
     /// ```text
     /// #[my_attr(value < 5)]
     ///           ^^^^^^^^^ what gets parsed
     /// ```
     ///
-    /// *This function is available if Syn is built with the `"parsing"`
+    /// *This function is available only if Syn is built with the `"parsing"`
     /// feature.*
     #[cfg(feature = "parsing")]
     pub fn parse_args<T: Parse>(&self) -> Result<T> {
         self.parse_args_with(T::parse)
     }
 
     /// Parse the arguments to the attribute using the given parser.
     ///
-    /// *This function is available if Syn is built with the `"parsing"`
+    /// *This function is available only if Syn is built with the `"parsing"`
     /// feature.*
     #[cfg(feature = "parsing")]
     pub fn parse_args_with<F: Parser>(&self, parser: F) -> Result<F::Output> {
         let parser = |input: ParseStream| {
             let args = enter_args(self, input)?;
             parse::parse_stream(parser, &args)
         };
         parser.parse2(self.tokens.clone())
     }
 
     /// Parses zero or more outer attributes from the stream.
     ///
-    /// *This function is available if Syn is built with the `"parsing"`
+    /// *This function is available only if Syn is built with the `"parsing"`
     /// feature.*
     #[cfg(feature = "parsing")]
     pub fn parse_outer(input: ParseStream) -> Result<Vec<Self>> {
         let mut attrs = Vec::new();
         while input.peek(Token![#]) {
             attrs.push(input.call(parsing::single_parse_outer)?);
         }
         Ok(attrs)
     }
 
     /// Parses zero or more inner attributes from the stream.
     ///
-    /// *This function is available if Syn is built with the `"parsing"`
+    /// *This function is available only if Syn is built with the `"parsing"`
     /// feature.*
     #[cfg(feature = "parsing")]
     pub fn parse_inner(input: ParseStream) -> Result<Vec<Self>> {
         let mut attrs = Vec::new();
         while input.peek(Token![#]) && input.peek2(Token![!]) {
             attrs.push(input.call(parsing::single_parse_inner)?);
         }
         Ok(attrs)
     }
 }
 
 #[cfg(feature = "parsing")]
-fn error_expected_args(attr: &Attribute) -> Error {
+fn expected_parentheses(attr: &Attribute) -> String {
     let style = match attr.style {
         AttrStyle::Outer => "#",
         AttrStyle::Inner(_) => "#!",
     };
 
     let mut path = String::new();
     for segment in &attr.path.segments {
         if !path.is_empty() || attr.path.leading_colon.is_some() {
             path += "::";
         }
         path += &segment.ident.to_string();
     }
 
-    let msg = format!("expected attribute arguments: {}[{}(...)]", style, path);
-
-    #[cfg(feature = "printing")]
-    return Error::new_spanned(attr, msg);
-
-    #[cfg(not(feature = "printing"))]
-    return Error::new(attr.bracket_token.span, msg);
+    format!("{}[{}(...)]", style, path)
 }
 
 #[cfg(feature = "parsing")]
 fn enter_args<'a>(attr: &Attribute, input: ParseStream<'a>) -> Result<ParseBuffer<'a>> {
     if input.is_empty() {
-        return Err(error_expected_args(attr));
+        let expected = expected_parentheses(attr);
+        let msg = format!("expected attribute arguments in parentheses: {}", expected);
+        return Err(crate::error::new2(
+            attr.pound_token.span,
+            attr.bracket_token.span,
+            msg,
+        ));
+    } else if input.peek(Token![=]) {
+        let expected = expected_parentheses(attr);
+        let msg = format!("expected parentheses: {}", expected);
+        return Err(input.error(msg));
     };
 
     let content;
     if input.peek(token::Paren) {
         parenthesized!(content in input);
     } else if input.peek(token::Bracket) {
         bracketed!(content in input);
     } else if input.peek(token::Brace) {
@@ -293,41 +304,40 @@ fn enter_args<'a>(attr: &Attribute, inpu
         Err(input.error("unexpected token in attribute arguments"))
     }
 }
 
 ast_enum! {
     /// Distinguishes between attributes that decorate an item and attributes
     /// that are contained within an item.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     ///
     /// # Outer attributes
     ///
     /// - `#[repr(transparent)]`
     /// - `/// # Example`
     /// - `/** Please file an issue */`
     ///
     /// # Inner attributes
     ///
     /// - `#![feature(proc_macro)]`
     /// - `//! # Example`
     /// - `/*! Please file an issue */`
-    #[cfg_attr(feature = "clone-impls", derive(Copy))]
     pub enum AttrStyle {
         Outer,
         Inner(Token![!]),
     }
 }
 
 ast_enum_of_structs! {
     /// Content of a compile-time structured attribute.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     ///
     /// ## Path
     ///
     /// A meta path is like the `test` in `#[test]`.
     ///
     /// ## List
     ///
@@ -355,29 +365,29 @@ ast_enum_of_structs! {
         /// A name-value pair within an attribute, like `feature = "nightly"`.
         NameValue(MetaNameValue),
     }
 }
 
 ast_struct! {
     /// A structured list within an attribute, like `derive(Copy, Clone)`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct MetaList {
         pub path: Path,
         pub paren_token: token::Paren,
         pub nested: Punctuated<NestedMeta, Token![,]>,
     }
 }
 
 ast_struct! {
     /// A name-value pair within an attribute, like `feature = "nightly"`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct MetaNameValue {
         pub path: Path,
         pub eq_token: Token![=],
         pub lit: Lit,
     }
 }
 
@@ -393,17 +403,17 @@ impl Meta {
             Meta::NameValue(meta) => &meta.path,
         }
     }
 }
 
 ast_enum_of_structs! {
     /// Element of a compile-time attribute list.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub enum NestedMeta {
         /// A structured meta item, like the `Copy` in `#[derive(Copy)]` which
         /// would be a nested `Meta::Path`.
         Meta(Meta),
 
         /// A Rust literal, like the `"new_name"` in `#[rename("new_name")]`.
         Lit(Lit),
@@ -424,18 +434,18 @@ ast_enum_of_structs! {
 ///     /* ... */
 /// }
 /// ```
 ///
 /// The implementation of this macro would want to parse its attribute arguments
 /// as type `AttributeArgs`.
 ///
 /// ```
-/// extern crate proc_macro;
-///
+/// # extern crate proc_macro;
+/// #
 /// use proc_macro::TokenStream;
 /// use syn::{parse_macro_input, AttributeArgs, ItemFn};
 ///
 /// # const IGNORE: &str = stringify! {
 /// #[proc_macro_attribute]
 /// # };
 /// pub fn my_attribute(args: TokenStream, input: TokenStream) -> TokenStream {
 ///     let args = parse_macro_input!(args as AttributeArgs);
@@ -459,27 +469,27 @@ where
     T: IntoIterator<Item = &'a Attribute>,
 {
     type Ret = iter::Filter<T::IntoIter, fn(&&Attribute) -> bool>;
 
     fn outer(self) -> Self::Ret {
         fn is_outer(attr: &&Attribute) -> bool {
             match attr.style {
                 AttrStyle::Outer => true,
-                _ => false,
+                AttrStyle::Inner(_) => false,
             }
         }
         self.into_iter().filter(is_outer)
     }
 
     fn inner(self) -> Self::Ret {
         fn is_inner(attr: &&Attribute) -> bool {
             match attr.style {
                 AttrStyle::Inner(_) => true,
-                _ => false,
+                AttrStyle::Outer => false,
             }
         }
         self.into_iter().filter(is_inner)
     }
 }
 
 #[cfg(feature = "parsing")]
 pub mod parsing {
diff --git a/third_party/rust/syn/src/buffer.rs b/third_party/rust/syn/src/buffer.rs
--- a/third_party/rust/syn/src/buffer.rs
+++ b/third_party/rust/syn/src/buffer.rs
@@ -1,12 +1,12 @@
 //! A stably addressed token buffer supporting efficient traversal based on a
 //! cheaply copyable cursor.
 //!
-//! *This module is available if Syn is built with the `"parsing"` feature.*
+//! *This module is available only if Syn is built with the `"parsing"` feature.*
 
 // This module is heavily commented as it contains most of the unsafe code in
 // Syn, and caution should be used when editing it. The public-facing interface
 // is 100% safe but the implementation is fragile internally.
 
 #[cfg(all(
     not(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "wasi"))),
     feature = "proc-macro"
@@ -31,17 +31,17 @@ enum Entry {
     // token tree, or null if this is the outermost level.
     End(*const Entry),
 }
 
 /// A buffer that can be efficiently traversed multiple times, unlike
 /// `TokenStream` which requires a deep copy in order to traverse more than
 /// once.
 ///
-/// *This type is available if Syn is built with the `"parsing"` feature.*
+/// *This type is available only if Syn is built with the `"parsing"` feature.*
 pub struct TokenBuffer {
     // NOTE: Do not derive clone on this - there are raw pointers inside which
     // will be messed up. Moving the `TokenBuffer` itself is safe as the actual
     // backing slices won't be moved.
     data: Box<[Entry]>,
 }
 
 impl TokenBuffer {
@@ -93,17 +93,17 @@ impl TokenBuffer {
         }
 
         TokenBuffer { data: entries }
     }
 
     /// Creates a `TokenBuffer` containing all the tokens from the input
     /// `TokenStream`.
     ///
-    /// *This method is available if Syn is built with both the `"parsing"` and
+    /// *This method is available only if Syn is built with both the `"parsing"` and
     /// `"proc-macro"` features.*
     #[cfg(all(
         not(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "wasi"))),
         feature = "proc-macro"
     ))]
     pub fn new(stream: pm::TokenStream) -> TokenBuffer {
         Self::new2(stream.into())
     }
@@ -128,18 +128,17 @@ impl TokenBuffer {
 /// and copied around.
 ///
 /// An empty `Cursor` can be created directly, or one may create a `TokenBuffer`
 /// object and get a cursor to its first token with `begin()`.
 ///
 /// Two cursors are equal if they have the same location in the same input
 /// stream, and have the same scope.
 ///
-/// *This type is available if Syn is built with the `"parsing"` feature.*
-#[derive(Copy, Clone, Eq, PartialEq)]
+/// *This type is available only if Syn is built with the `"parsing"` feature.*
 pub struct Cursor<'a> {
     // The current entry which the `Cursor` is pointing at.
     ptr: *const Entry,
     // This is the only `Entry::End(..)` object which this cursor is allowed to
     // point at. All other `End` objects are skipped over in `Cursor::create`.
     scope: *const Entry,
     // Cursor is covariant in 'a. This field ensures that our pointers are still
     // valid.
@@ -196,37 +195,38 @@ impl<'a> Cursor<'a> {
 
     /// Bump the cursor to point at the next token after the current one. This
     /// is undefined behavior if the cursor is currently looking at an
     /// `Entry::End`.
     unsafe fn bump(self) -> Cursor<'a> {
         Cursor::create(self.ptr.offset(1), self.scope)
     }
 
-    /// If the cursor is looking at a `None`-delimited group, move it to look at
-    /// the first token inside instead. If the group is empty, this will move
+    /// While the cursor is looking at a `None`-delimited group, move it to look
+    /// at the first token inside instead. If the group is empty, this will move
     /// the cursor past the `None`-delimited group.
     ///
     /// WARNING: This mutates its argument.
     fn ignore_none(&mut self) {
-        if let Entry::Group(group, buf) = self.entry() {
+        while let Entry::Group(group, buf) = self.entry() {
             if group.delimiter() == Delimiter::None {
                 // NOTE: We call `Cursor::create` here to make sure that
                 // situations where we should immediately exit the span after
                 // entering it are handled correctly.
                 unsafe {
                     *self = Cursor::create(&buf.data[0], self.scope);
                 }
+            } else {
+                break;
             }
         }
     }
 
     /// Checks whether the cursor is currently pointing at the end of its valid
     /// scope.
-    #[inline]
     pub fn eof(self) -> bool {
         // We're at eof if we're at the end of our scope.
         self.ptr == self.scope
     }
 
     /// If the cursor is pointing at a `Group` with the given delimiter, returns
     /// a cursor into that group and one pointing to the next `TokenTree`.
     pub fn group(mut self, delim: Delimiter) -> Option<(Cursor<'a>, Span, Cursor<'a>)> {
@@ -337,16 +337,54 @@ impl<'a> Cursor<'a> {
         match self.entry() {
             Entry::Group(group, _) => group.span(),
             Entry::Literal(l) => l.span(),
             Entry::Ident(t) => t.span(),
             Entry::Punct(o) => o.span(),
             Entry::End(..) => Span::call_site(),
         }
     }
+
+    /// Skip over the next token without cloning it. Returns `None` if this
+    /// cursor points to eof.
+    ///
+    /// This method treats `'lifetimes` as a single token.
+    pub(crate) fn skip(self) -> Option<Cursor<'a>> {
+        match self.entry() {
+            Entry::End(..) => None,
+
+            // Treat lifetimes as a single tt for the purposes of 'skip'.
+            Entry::Punct(op) if op.as_char() == '\'' && op.spacing() == Spacing::Joint => {
+                let next = unsafe { self.bump() };
+                match next.entry() {
+                    Entry::Ident(_) => Some(unsafe { next.bump() }),
+                    _ => Some(next),
+                }
+            }
+            _ => Some(unsafe { self.bump() }),
+        }
+    }
+}
+
+impl<'a> Copy for Cursor<'a> {}
+
+impl<'a> Clone for Cursor<'a> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+impl<'a> Eq for Cursor<'a> {}
+
+impl<'a> PartialEq for Cursor<'a> {
+    fn eq(&self, other: &Self) -> bool {
+        let Cursor { ptr, scope, marker } = self;
+        let _ = marker;
+        *ptr == other.ptr && *scope == other.scope
+    }
 }
 
 pub(crate) fn same_scope(a: Cursor, b: Cursor) -> bool {
     a.scope == b.scope
 }
 
 pub(crate) fn open_span_of_group(cursor: Cursor) -> Span {
     match cursor.entry() {
diff --git a/third_party/rust/syn/src/custom_keyword.rs b/third_party/rust/syn/src/custom_keyword.rs
--- a/third_party/rust/syn/src/custom_keyword.rs
+++ b/third_party/rust/syn/src/custom_keyword.rs
@@ -81,46 +81,46 @@
 ///                 value: input.parse()?,
 ///             })
 ///         } else {
 ///             Err(lookahead.error())
 ///         }
 ///     }
 /// }
 /// ```
-#[macro_export(local_inner_macros)]
+#[macro_export]
 macro_rules! custom_keyword {
     ($ident:ident) => {
         #[allow(non_camel_case_types)]
         pub struct $ident {
             pub span: $crate::export::Span,
         }
 
         #[doc(hidden)]
-        #[allow(non_snake_case)]
+        #[allow(dead_code, non_snake_case)]
         pub fn $ident<__S: $crate::export::IntoSpans<[$crate::export::Span; 1]>>(
             span: __S,
         ) -> $ident {
             $ident {
                 span: $crate::export::IntoSpans::into_spans(span)[0],
             }
         }
 
         impl $crate::export::Default for $ident {
             fn default() -> Self {
                 $ident {
                     span: $crate::export::Span::call_site(),
                 }
             }
         }
 
-        impl_parse_for_custom_keyword!($ident);
-        impl_to_tokens_for_custom_keyword!($ident);
-        impl_clone_for_custom_keyword!($ident);
-        impl_extra_traits_for_custom_keyword!($ident);
+        $crate::impl_parse_for_custom_keyword!($ident);
+        $crate::impl_to_tokens_for_custom_keyword!($ident);
+        $crate::impl_clone_for_custom_keyword!($ident);
+        $crate::impl_extra_traits_for_custom_keyword!($ident);
     };
 }
 
 // Not public API.
 #[cfg(feature = "parsing")]
 #[doc(hidden)]
 #[macro_export]
 macro_rules! impl_parse_for_custom_keyword {
diff --git a/third_party/rust/syn/src/custom_punctuation.rs b/third_party/rust/syn/src/custom_punctuation.rs
--- a/third_party/rust/syn/src/custom_punctuation.rs
+++ b/third_party/rust/syn/src/custom_punctuation.rs
@@ -69,67 +69,67 @@
 ///     Ok(tokens)
 /// }
 ///
 /// fn main() {
 ///     let input = r#" a::b </> c::d::e "#;
 ///     let _: PathSegments = syn::parse_str(input).unwrap();
 /// }
 /// ```
-#[macro_export(local_inner_macros)]
+#[macro_export]
 macro_rules! custom_punctuation {
     ($ident:ident, $($tt:tt)+) => {
         pub struct $ident {
-            pub spans: custom_punctuation_repr!($($tt)+),
+            pub spans: $crate::custom_punctuation_repr!($($tt)+),
         }
 
         #[doc(hidden)]
-        #[allow(non_snake_case)]
-        pub fn $ident<__S: $crate::export::IntoSpans<custom_punctuation_repr!($($tt)+)>>(
+        #[allow(dead_code, non_snake_case)]
+        pub fn $ident<__S: $crate::export::IntoSpans<$crate::custom_punctuation_repr!($($tt)+)>>(
             spans: __S,
         ) -> $ident {
-            let _validate_len = 0 $(+ custom_punctuation_len!(strict, $tt))*;
+            let _validate_len = 0 $(+ $crate::custom_punctuation_len!(strict, $tt))*;
             $ident {
                 spans: $crate::export::IntoSpans::into_spans(spans)
             }
         }
 
         impl $crate::export::Default for $ident {
             fn default() -> Self {
                 $ident($crate::export::Span::call_site())
             }
         }
 
-        impl_parse_for_custom_punctuation!($ident, $($tt)+);
-        impl_to_tokens_for_custom_punctuation!($ident, $($tt)+);
-        impl_clone_for_custom_punctuation!($ident, $($tt)+);
-        impl_extra_traits_for_custom_punctuation!($ident, $($tt)+);
+        $crate::impl_parse_for_custom_punctuation!($ident, $($tt)+);
+        $crate::impl_to_tokens_for_custom_punctuation!($ident, $($tt)+);
+        $crate::impl_clone_for_custom_punctuation!($ident, $($tt)+);
+        $crate::impl_extra_traits_for_custom_punctuation!($ident, $($tt)+);
     };
 }
 
 // Not public API.
 #[cfg(feature = "parsing")]
 #[doc(hidden)]
-#[macro_export(local_inner_macros)]
+#[macro_export]
 macro_rules! impl_parse_for_custom_punctuation {
     ($ident:ident, $($tt:tt)+) => {
         impl $crate::token::CustomToken for $ident {
             fn peek(cursor: $crate::buffer::Cursor) -> bool {
-                $crate::token::parsing::peek_punct(cursor, stringify_punct!($($tt)+))
+                $crate::token::parsing::peek_punct(cursor, $crate::stringify_punct!($($tt)+))
             }
 
             fn display() -> &'static $crate::export::str {
-                custom_punctuation_concat!("`", stringify_punct!($($tt)+), "`")
+                concat!("`", $crate::stringify_punct!($($tt)+), "`")
             }
         }
 
         impl $crate::parse::Parse for $ident {
             fn parse(input: $crate::parse::ParseStream) -> $crate::parse::Result<$ident> {
-                let spans: custom_punctuation_repr!($($tt)+) =
-                    $crate::token::parsing::punct(input, stringify_punct!($($tt)+))?;
+                let spans: $crate::custom_punctuation_repr!($($tt)+) =
+                    $crate::token::parsing::punct(input, $crate::stringify_punct!($($tt)+))?;
                 Ok($ident(spans))
             }
         }
     };
 }
 
 // Not public API.
 #[cfg(not(feature = "parsing"))]
@@ -137,22 +137,22 @@ macro_rules! impl_parse_for_custom_punct
 #[macro_export]
 macro_rules! impl_parse_for_custom_punctuation {
     ($ident:ident, $($tt:tt)+) => {};
 }
 
 // Not public API.
 #[cfg(feature = "printing")]
 #[doc(hidden)]
-#[macro_export(local_inner_macros)]
+#[macro_export]
 macro_rules! impl_to_tokens_for_custom_punctuation {
     ($ident:ident, $($tt:tt)+) => {
         impl $crate::export::ToTokens for $ident {
             fn to_tokens(&self, tokens: &mut $crate::export::TokenStream2) {
-                $crate::token::printing::punct(stringify_punct!($($tt)+), &self.spans, tokens)
+                $crate::token::printing::punct($crate::stringify_punct!($($tt)+), &self.spans, tokens)
             }
         }
     };
 }
 
 // Not public API.
 #[cfg(not(feature = "printing"))]
 #[doc(hidden)]
@@ -216,26 +216,26 @@ macro_rules! impl_extra_traits_for_custo
 #[doc(hidden)]
 #[macro_export]
 macro_rules! impl_extra_traits_for_custom_punctuation {
     ($ident:ident, $($tt:tt)+) => {};
 }
 
 // Not public API.
 #[doc(hidden)]
-#[macro_export(local_inner_macros)]
+#[macro_export]
 macro_rules! custom_punctuation_repr {
     ($($tt:tt)+) => {
-        [$crate::export::Span; 0 $(+ custom_punctuation_len!(lenient, $tt))+]
+        [$crate::export::Span; 0 $(+ $crate::custom_punctuation_len!(lenient, $tt))+]
     };
 }
 
 // Not public API.
 #[doc(hidden)]
-#[macro_export(local_inner_macros)]
+#[macro_export]
 #[rustfmt::skip]
 macro_rules! custom_punctuation_len {
     ($mode:ident, +)     => { 1 };
     ($mode:ident, +=)    => { 2 };
     ($mode:ident, &)     => { 1 };
     ($mode:ident, &&)    => { 2 };
     ($mode:ident, &=)    => { 2 };
     ($mode:ident, @)     => { 1 };
@@ -274,17 +274,17 @@ macro_rules! custom_punctuation_len {
     ($mode:ident, <<=)   => { 3 };
     ($mode:ident, >>)    => { 2 };
     ($mode:ident, >>=)   => { 3 };
     ($mode:ident, *)     => { 1 };
     ($mode:ident, -)     => { 1 };
     ($mode:ident, -=)    => { 2 };
     ($mode:ident, ~)     => { 1 };
     (lenient, $tt:tt)    => { 0 };
-    (strict, $tt:tt)     => {{ custom_punctuation_unexpected!($tt); 0 }};
+    (strict, $tt:tt)     => {{ $crate::custom_punctuation_unexpected!($tt); 0 }};
 }
 
 // Not public API.
 #[doc(hidden)]
 #[macro_export]
 macro_rules! custom_punctuation_unexpected {
     () => {};
 }
@@ -292,18 +292,8 @@ macro_rules! custom_punctuation_unexpect
 // Not public API.
 #[doc(hidden)]
 #[macro_export]
 macro_rules! stringify_punct {
     ($($tt:tt)+) => {
         concat!($(stringify!($tt)),+)
     };
 }
-
-// Not public API.
-// Without this, local_inner_macros breaks when looking for concat!
-#[doc(hidden)]
-#[macro_export]
-macro_rules! custom_punctuation_concat {
-    ($($tt:tt)*) => {
-        concat!($($tt)*)
-    };
-}
diff --git a/third_party/rust/syn/src/data.rs b/third_party/rust/syn/src/data.rs
--- a/third_party/rust/syn/src/data.rs
+++ b/third_party/rust/syn/src/data.rs
@@ -1,15 +1,15 @@
 use super::*;
 use crate::punctuated::Punctuated;
 
 ast_struct! {
     /// An enum variant.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub struct Variant {
         /// Attributes tagged on the variant.
         pub attrs: Vec<Attribute>,
 
         /// Name of the variant.
         pub ident: Ident,
 
@@ -19,17 +19,17 @@ ast_struct! {
         /// Explicit discriminant: `Variant = 1`
         pub discriminant: Option<(Token![=], Expr)>,
     }
 }
 
 ast_enum_of_structs! {
     /// Data stored within an enum variant or struct.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     ///
     /// # Syntax tree enum
     ///
     /// This type is a [syntax tree enum].
     ///
     /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums
     //
@@ -47,28 +47,28 @@ ast_enum_of_structs! {
         Unit,
     }
 }
 
 ast_struct! {
     /// Named fields of a struct or struct variant such as `Point { x: f64,
     /// y: f64 }`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct FieldsNamed {
         pub brace_token: token::Brace,
         pub named: Punctuated<Field, Token![,]>,
     }
 }
 
 ast_struct! {
     /// Unnamed fields of a tuple struct or tuple variant such as `Some(T)`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct FieldsUnnamed {
         pub paren_token: token::Paren,
         pub unnamed: Punctuated<Field, Token![,]>,
     }
 }
 
 impl Fields {
@@ -88,16 +88,34 @@ impl Fields {
     /// struct or variant's fields uniformly.
     pub fn iter_mut(&mut self) -> punctuated::IterMut<Field> {
         match self {
             Fields::Unit => crate::punctuated::empty_punctuated_iter_mut(),
             Fields::Named(f) => f.named.iter_mut(),
             Fields::Unnamed(f) => f.unnamed.iter_mut(),
         }
     }
+
+    /// Returns the number of fields.
+    pub fn len(&self) -> usize {
+        match self {
+            Fields::Unit => 0,
+            Fields::Named(f) => f.named.len(),
+            Fields::Unnamed(f) => f.unnamed.len(),
+        }
+    }
+
+    /// Returns `true` if there are zero fields.
+    pub fn is_empty(&self) -> bool {
+        match self {
+            Fields::Unit => true,
+            Fields::Named(f) => f.named.is_empty(),
+            Fields::Unnamed(f) => f.unnamed.is_empty(),
+        }
+    }
 }
 
 impl IntoIterator for Fields {
     type Item = Field;
     type IntoIter = punctuated::IntoIter<Field>;
 
     fn into_iter(self) -> Self::IntoIter {
         match self {
@@ -124,17 +142,17 @@ impl<'a> IntoIterator for &'a mut Fields
     fn into_iter(self) -> Self::IntoIter {
         self.iter_mut()
     }
 }
 
 ast_struct! {
     /// A field of a struct or enum variant.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub struct Field {
         /// Attributes tagged on the field.
         pub attrs: Vec<Attribute>,
 
         /// Visibility of the field.
         pub vis: Visibility,
 
@@ -149,17 +167,17 @@ ast_struct! {
         pub ty: Type,
     }
 }
 
 ast_enum_of_structs! {
     /// The visibility level of an item: inherited or `pub` or
     /// `pub(restricted)`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     ///
     /// # Syntax tree enum
     ///
     /// This type is a [syntax tree enum].
     ///
     /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums
     //
@@ -179,58 +197,61 @@ ast_enum_of_structs! {
         /// An inherited visibility, which usually means private.
         Inherited,
     }
 }
 
 ast_struct! {
     /// A public visibility level: `pub`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct VisPublic {
         pub pub_token: Token![pub],
     }
 }
 
 ast_struct! {
     /// A crate-level visibility: `crate`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct VisCrate {
         pub crate_token: Token![crate],
     }
 }
 
 ast_struct! {
     /// A visibility level restricted to some path: `pub(self)` or
     /// `pub(super)` or `pub(crate)` or `pub(in some::module)`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct VisRestricted {
         pub pub_token: Token![pub],
         pub paren_token: token::Paren,
         pub in_token: Option<Token![in]>,
         pub path: Box<Path>,
     }
 }
 
 #[cfg(feature = "parsing")]
 pub mod parsing {
     use super::*;
 
     use crate::ext::IdentExt;
+    use crate::parse::discouraged::Speculative;
     use crate::parse::{Parse, ParseStream, Result};
 
     impl Parse for Variant {
         fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let _visibility: Visibility = input.parse()?;
             Ok(Variant {
-                attrs: input.call(Attribute::parse_outer)?,
+                attrs,
                 ident: input.parse()?,
                 fields: {
                     if input.peek(token::Brace) {
                         Fields::Named(input.parse()?)
                     } else if input.peek(token::Paren) {
                         Fields::Unnamed(input.parse()?)
                     } else {
                         Fields::Unit
@@ -290,68 +311,99 @@ pub mod parsing {
                 colon_token: None,
                 ty: input.parse()?,
             })
         }
     }
 
     impl Parse for Visibility {
         fn parse(input: ParseStream) -> Result<Self> {
+            // Recognize an empty None-delimited group, as produced by a $:vis
+            // matcher that matched no tokens.
+            if input.peek(token::Group) {
+                let ahead = input.fork();
+                let group = crate::group::parse_group(&ahead)?;
+                if group.content.is_empty() {
+                    input.advance_to(&ahead);
+                    return Ok(Visibility::Inherited);
+                }
+            }
+
             if input.peek(Token![pub]) {
                 Self::parse_pub(input)
             } else if input.peek(Token![crate]) {
                 Self::parse_crate(input)
             } else {
                 Ok(Visibility::Inherited)
             }
         }
     }
 
     impl Visibility {
         fn parse_pub(input: ParseStream) -> Result<Self> {
             let pub_token = input.parse::<Token![pub]>()?;
 
             if input.peek(token::Paren) {
-                // TODO: optimize using advance_to
                 let ahead = input.fork();
-                let mut content;
-                parenthesized!(content in ahead);
 
+                let content;
+                let paren_token = parenthesized!(content in ahead);
                 if content.peek(Token![crate])
                     || content.peek(Token![self])
                     || content.peek(Token![super])
                 {
+                    let path = content.call(Ident::parse_any)?;
+
+                    // Ensure there are no additional tokens within `content`.
+                    // Without explicitly checking, we may misinterpret a tuple
+                    // field as a restricted visibility, causing a parse error.
+                    // e.g. `pub (crate::A, crate::B)` (Issue #720).
+                    if content.is_empty() {
+                        input.advance_to(&ahead);
+                        return Ok(Visibility::Restricted(VisRestricted {
+                            pub_token,
+                            paren_token,
+                            in_token: None,
+                            path: Box::new(Path::from(path)),
+                        }));
+                    }
+                } else if content.peek(Token![in]) {
+                    let in_token: Token![in] = content.parse()?;
+                    let path = content.call(Path::parse_mod_style)?;
+
+                    input.advance_to(&ahead);
                     return Ok(Visibility::Restricted(VisRestricted {
                         pub_token,
-                        paren_token: parenthesized!(content in input),
-                        in_token: None,
-                        path: Box::new(Path::from(content.call(Ident::parse_any)?)),
-                    }));
-                } else if content.peek(Token![in]) {
-                    return Ok(Visibility::Restricted(VisRestricted {
-                        pub_token,
-                        paren_token: parenthesized!(content in input),
-                        in_token: Some(content.parse()?),
-                        path: Box::new(content.call(Path::parse_mod_style)?),
+                        paren_token,
+                        in_token: Some(in_token),
+                        path: Box::new(path),
                     }));
                 }
             }
 
             Ok(Visibility::Public(VisPublic { pub_token }))
         }
 
         fn parse_crate(input: ParseStream) -> Result<Self> {
             if input.peek2(Token![::]) {
                 Ok(Visibility::Inherited)
             } else {
                 Ok(Visibility::Crate(VisCrate {
                     crate_token: input.parse()?,
                 }))
             }
         }
+
+        #[cfg(feature = "full")]
+        pub(crate) fn is_some(&self) -> bool {
+            match self {
+                Visibility::Inherited => false,
+                _ => true,
+            }
+        }
     }
 }
 
 #[cfg(feature = "printing")]
 mod printing {
     use super::*;
 
     use proc_macro2::TokenStream;
diff --git a/third_party/rust/syn/src/derive.rs b/third_party/rust/syn/src/derive.rs
--- a/third_party/rust/syn/src/derive.rs
+++ b/third_party/rust/syn/src/derive.rs
@@ -1,15 +1,15 @@
 use super::*;
 use crate::punctuated::Punctuated;
 
 ast_struct! {
     /// Data structure sent to a `proc_macro_derive` macro.
     ///
-    /// *This type is available if Syn is built with the `"derive"` feature.*
+    /// *This type is available only if Syn is built with the `"derive"` feature.*
     pub struct DeriveInput {
         /// Attributes tagged on the whole struct or enum.
         pub attrs: Vec<Attribute>,
 
         /// Visibility of the struct or enum.
         pub vis: Visibility,
 
         /// Name of the struct or enum.
@@ -21,17 +21,17 @@ ast_struct! {
         /// Data within the struct or enum.
         pub data: Data,
     }
 }
 
 ast_enum_of_structs! {
     /// The storage of a struct, enum or union data structure.
     ///
-    /// *This type is available if Syn is built with the `"derive"` feature.*
+    /// *This type is available only if Syn is built with the `"derive"` feature.*
     ///
     /// # Syntax tree enum
     ///
     /// This type is a [syntax tree enum].
     ///
     /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums
     //
     // TODO: change syntax-tree-enum link to an intra rustdoc link, currently
@@ -48,41 +48,41 @@ ast_enum_of_structs! {
     }
 
     do_not_generate_to_tokens
 }
 
 ast_struct! {
     /// A struct input to a `proc_macro_derive` macro.
     ///
-    /// *This type is available if Syn is built with the `"derive"`
+    /// *This type is available only if Syn is built with the `"derive"`
     /// feature.*
     pub struct DataStruct {
         pub struct_token: Token![struct],
         pub fields: Fields,
         pub semi_token: Option<Token![;]>,
     }
 }
 
 ast_struct! {
     /// An enum input to a `proc_macro_derive` macro.
     ///
-    /// *This type is available if Syn is built with the `"derive"`
+    /// *This type is available only if Syn is built with the `"derive"`
     /// feature.*
     pub struct DataEnum {
         pub enum_token: Token![enum],
         pub brace_token: token::Brace,
         pub variants: Punctuated<Variant, Token![,]>,
     }
 }
 
 ast_struct! {
     /// An untagged union input to a `proc_macro_derive` macro.
     ///
-    /// *This type is available if Syn is built with the `"derive"`
+    /// *This type is available only if Syn is built with the `"derive"`
     /// feature.*
     pub struct DataUnion {
         pub union_token: Token![union],
         pub fields: FieldsNamed,
     }
 }
 
 #[cfg(feature = "parsing")]
diff --git a/third_party/rust/syn/src/discouraged.rs b/third_party/rust/syn/src/discouraged.rs
--- a/third_party/rust/syn/src/discouraged.rs
+++ b/third_party/rust/syn/src/discouraged.rs
@@ -11,17 +11,17 @@ pub trait Speculative {
     /// stream to the fork to "commit" the parsing from the fork to the main
     /// stream.
     ///
     /// If you can avoid doing this, you should, as it limits the ability to
     /// generate useful errors. That said, it is often the only way to parse
     /// syntax of the form `A* B*` for arbitrary syntax `A` and `B`. The problem
     /// is that when the fork fails to parse an `A`, it's impossible to tell
     /// whether that was because of a syntax error and the user meant to provide
-    /// an `A`, or that the `A`s are finished and its time to start parsing
+    /// an `A`, or that the `A`s are finished and it's time to start parsing
     /// `B`s. Use with care.
     ///
     /// Also note that if `A` is a subset of `B`, `A* B*` can be parsed by
     /// parsing `B*` and removing the leading members of `A` from the
     /// repetition, bypassing the need to involve the downsides associated with
     /// speculative parsing.
     ///
     /// [`ParseStream::fork`]: ParseBuffer::fork
@@ -67,17 +67,16 @@ pub trait Speculative {
     /// # }
     ///
     /// impl Parse for PathSegment {
     ///     fn parse(input: ParseStream) -> Result<Self> {
     ///         if input.peek(Token![super])
     ///             || input.peek(Token![self])
     ///             || input.peek(Token![Self])
     ///             || input.peek(Token![crate])
-    ///             || input.peek(Token![extern])
     ///         {
     ///             let ident = input.call(Ident::parse_any)?;
     ///             return Ok(PathSegment::from(ident));
     ///         }
     ///
     ///         let ident = input.parse()?;
     ///         if input.peek(Token![::]) && input.peek3(Token![<]) {
     ///             return Ok(PathSegment {
@@ -159,13 +158,37 @@ pub trait Speculative {
 }
 
 impl<'a> Speculative for ParseBuffer<'a> {
     fn advance_to(&self, fork: &Self) {
         if !crate::buffer::same_scope(self.cursor(), fork.cursor()) {
             panic!("Fork was not derived from the advancing parse stream");
         }
 
+        let (self_unexp, self_sp) = inner_unexpected(self);
+        let (fork_unexp, fork_sp) = inner_unexpected(fork);
+        if !Rc::ptr_eq(&self_unexp, &fork_unexp) {
+            match (fork_sp, self_sp) {
+                // Unexpected set on the fork, but not on `self`, copy it over.
+                (Some(span), None) => {
+                    self_unexp.set(Unexpected::Some(span));
+                }
+                // Unexpected unset. Use chain to propagate errors from fork.
+                (None, None) => {
+                    fork_unexp.set(Unexpected::Chain(self_unexp));
+
+                    // Ensure toplevel 'unexpected' tokens from the fork don't
+                    // bubble up the chain by replacing the root `unexpected`
+                    // pointer, only 'unexpected' tokens from existing group
+                    // parsers should bubble.
+                    fork.unexpected
+                        .set(Some(Rc::new(Cell::new(Unexpected::None))));
+                }
+                // Unexpected has been set on `self`. No changes needed.
+                (_, Some(_)) => {}
+            }
+        }
+
         // See comment on `cell` in the struct definition.
         self.cell
             .set(unsafe { mem::transmute::<Cursor, Cursor<'static>>(fork.cursor()) })
     }
 }
diff --git a/third_party/rust/syn/src/error.rs b/third_party/rust/syn/src/error.rs
--- a/third_party/rust/syn/src/error.rs
+++ b/third_party/rust/syn/src/error.rs
@@ -1,9 +1,8 @@
-use std;
 use std::fmt::{self, Debug, Display};
 use std::iter::FromIterator;
 use std::slice;
 use std::vec;
 
 use proc_macro2::{
     Delimiter, Group, Ident, LexError, Literal, Punct, Spacing, Span, TokenStream, TokenTree,
 };
@@ -27,18 +26,18 @@ pub type Result<T> = std::result::Result
 /// message than simply panicking the macro.
 ///
 /// [`compile_error!`]: https://doc.rust-lang.org/std/macro.compile_error.html
 ///
 /// When parsing macro input, the [`parse_macro_input!`] macro handles the
 /// conversion to `compile_error!` automatically.
 ///
 /// ```
-/// extern crate proc_macro;
-///
+/// # extern crate proc_macro;
+/// #
 /// use proc_macro::TokenStream;
 /// use syn::{parse_macro_input, AttributeArgs, ItemFn};
 ///
 /// # const IGNORE: &str = stringify! {
 /// #[proc_macro_attribute]
 /// # };
 /// pub fn my_attr(args: TokenStream, input: TokenStream) -> TokenStream {
 ///     let args = parse_macro_input!(args as AttributeArgs);
@@ -77,17 +76,16 @@ pub type Result<T> = std::result::Result
 /// #     use proc_macro2::TokenStream;
 /// #     use syn::{DeriveInput, Result};
 /// #
 /// #     pub fn my_derive(input: DeriveInput) -> Result<TokenStream> {
 /// #         unimplemented!()
 /// #     }
 /// # }
 /// ```
-#[derive(Clone)]
 pub struct Error {
     messages: Vec<ErrorMessage>,
 }
 
 struct ErrorMessage {
     // Span is implemented as an index into a thread-local interner to keep the
     // size small. It is not safe to access from a different thread. We want
     // errors to be Send and Sync to play nicely with the Failure crate, so pin
@@ -245,16 +243,27 @@ pub fn new_at<T: Display>(scope: Span, c
     if cursor.eof() {
         Error::new(scope, format!("unexpected end of input, {}", message))
     } else {
         let span = crate::buffer::open_span_of_group(cursor);
         Error::new(span, message)
     }
 }
 
+#[cfg(all(feature = "parsing", any(feature = "full", feature = "derive")))]
+pub fn new2<T: Display>(start: Span, end: Span, message: T) -> Error {
+    Error {
+        messages: vec![ErrorMessage {
+            start_span: ThreadBound::new(start),
+            end_span: ThreadBound::new(end),
+            message: message.to_string(),
+        }],
+    }
+}
+
 impl Debug for Error {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         if self.messages.len() == 1 {
             formatter
                 .debug_tuple("Error")
                 .field(&self.messages[0])
                 .finish()
         } else {
@@ -273,16 +282,24 @@ impl Debug for ErrorMessage {
 }
 
 impl Display for Error {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         formatter.write_str(&self.messages[0].message)
     }
 }
 
+impl Clone for Error {
+    fn clone(&self) -> Self {
+        Error {
+            messages: self.messages.clone(),
+        }
+    }
+}
+
 impl Clone for ErrorMessage {
     fn clone(&self) -> Self {
         let start = self
             .start_span
             .get()
             .cloned()
             .unwrap_or_else(Span::call_site);
         let end = self.end_span.get().cloned().unwrap_or_else(Span::call_site);
@@ -350,8 +367,16 @@ impl<'a> Iterator for Iter<'a> {
     type Item = Error;
 
     fn next(&mut self) -> Option<Self::Item> {
         Some(Error {
             messages: vec![self.messages.next()?.clone()],
         })
     }
 }
+
+impl Extend<Error> for Error {
+    fn extend<T: IntoIterator<Item = Error>>(&mut self, iter: T) {
+        for err in iter {
+            self.combine(err);
+        }
+    }
+}
diff --git a/third_party/rust/syn/src/expr.rs b/third_party/rust/syn/src/expr.rs
--- a/third_party/rust/syn/src/expr.rs
+++ b/third_party/rust/syn/src/expr.rs
@@ -1,23 +1,26 @@
 use super::*;
 use crate::punctuated::Punctuated;
-#[cfg(feature = "extra-traits")]
-use crate::tt::TokenStreamHelper;
+#[cfg(feature = "full")]
+use crate::reserved::Reserved;
 use proc_macro2::{Span, TokenStream};
-#[cfg(feature = "extra-traits")]
+#[cfg(feature = "printing")]
+use quote::IdentFragment;
+#[cfg(feature = "printing")]
+use std::fmt::{self, Display};
 use std::hash::{Hash, Hasher};
-#[cfg(all(feature = "parsing", feature = "full"))]
+#[cfg(feature = "parsing")]
 use std::mem;
 
 ast_enum_of_structs! {
     /// A Rust expression.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
-    /// feature.*
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
+    /// feature, but most of the variants are not available unless "full" is enabled.*
     ///
     /// # Syntax tree enums
     ///
     /// This type is a syntax tree enum. In Syn this and other syntax tree enums
     /// are designed to be traversed using the following rebinding idiom.
     ///
     /// ```
     /// # use syn::Expr;
@@ -78,17 +81,17 @@ ast_enum_of_structs! {
     /// if let Expr::Tuple(base) = *discriminant.base {
     /// # }
     /// # }
     /// ```
     ///
     /// A sign that you may not be choosing the right variable names is if you
     /// see names getting repeated in your code, like accessing
     /// `receiver.receiver` or `pat.pat` or `cond.cond`.
-    pub enum Expr #manual_extra_traits {
+    pub enum Expr {
         /// A slice literal expression: `[a, b, c, d]`.
         Array(ExprArray),
 
         /// An assignment expression: `a = compute()`.
         Assign(ExprAssign),
 
         /// A compound assignment expression: `counter += 1`.
         AssignOp(ExprAssignOp),
@@ -223,191 +226,191 @@ ast_enum_of_structs! {
         #[doc(hidden)]
         __Nonexhaustive,
     }
 }
 
 ast_struct! {
     /// A slice literal expression: `[a, b, c, d]`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprArray #full {
         pub attrs: Vec<Attribute>,
         pub bracket_token: token::Bracket,
         pub elems: Punctuated<Expr, Token![,]>,
     }
 }
 
 ast_struct! {
     /// An assignment expression: `a = compute()`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprAssign #full {
         pub attrs: Vec<Attribute>,
         pub left: Box<Expr>,
         pub eq_token: Token![=],
         pub right: Box<Expr>,
     }
 }
 
 ast_struct! {
     /// A compound assignment expression: `counter += 1`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprAssignOp #full {
         pub attrs: Vec<Attribute>,
         pub left: Box<Expr>,
         pub op: BinOp,
         pub right: Box<Expr>,
     }
 }
 
 ast_struct! {
     /// An async block: `async { ... }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprAsync #full {
         pub attrs: Vec<Attribute>,
         pub async_token: Token![async],
         pub capture: Option<Token![move]>,
         pub block: Block,
     }
 }
 
 ast_struct! {
     /// An await expression: `fut.await`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprAwait #full {
         pub attrs: Vec<Attribute>,
         pub base: Box<Expr>,
         pub dot_token: Token![.],
         pub await_token: token::Await,
     }
 }
 
 ast_struct! {
     /// A binary operation: `a + b`, `a * b`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct ExprBinary {
         pub attrs: Vec<Attribute>,
         pub left: Box<Expr>,
         pub op: BinOp,
         pub right: Box<Expr>,
     }
 }
 
 ast_struct! {
     /// A blocked scope: `{ ... }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprBlock #full {
         pub attrs: Vec<Attribute>,
         pub label: Option<Label>,
         pub block: Block,
     }
 }
 
 ast_struct! {
     /// A box expression: `box f`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprBox #full {
         pub attrs: Vec<Attribute>,
         pub box_token: Token![box],
         pub expr: Box<Expr>,
     }
 }
 
 ast_struct! {
     /// A `break`, with an optional label to break and an optional
     /// expression.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprBreak #full {
         pub attrs: Vec<Attribute>,
         pub break_token: Token![break],
         pub label: Option<Lifetime>,
         pub expr: Option<Box<Expr>>,
     }
 }
 
 ast_struct! {
     /// A function call expression: `invoke(a, b)`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct ExprCall {
         pub attrs: Vec<Attribute>,
         pub func: Box<Expr>,
         pub paren_token: token::Paren,
         pub args: Punctuated<Expr, Token![,]>,
     }
 }
 
 ast_struct! {
     /// A cast expression: `foo as f64`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct ExprCast {
         pub attrs: Vec<Attribute>,
         pub expr: Box<Expr>,
         pub as_token: Token![as],
         pub ty: Box<Type>,
     }
 }
 
 ast_struct! {
     /// A closure expression: `|a, b| a + b`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprClosure #full {
         pub attrs: Vec<Attribute>,
         pub asyncness: Option<Token![async]>,
         pub movability: Option<Token![static]>,
         pub capture: Option<Token![move]>,
         pub or1_token: Token![|],
         pub inputs: Punctuated<Pat, Token![,]>,
         pub or2_token: Token![|],
         pub output: ReturnType,
         pub body: Box<Expr>,
     }
 }
 
 ast_struct! {
     /// A `continue`, with an optional label.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprContinue #full {
         pub attrs: Vec<Attribute>,
         pub continue_token: Token![continue],
         pub label: Option<Lifetime>,
     }
 }
 
 ast_struct! {
     /// Access of a named struct field (`obj.k`) or unnamed tuple struct
     /// field (`obj.0`).
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprField {
         pub attrs: Vec<Attribute>,
         pub base: Box<Expr>,
         pub dot_token: Token![.],
         pub member: Member,
     }
 }
 
 ast_struct! {
     /// A for loop: `for pat in expr { ... }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprForLoop #full {
         pub attrs: Vec<Attribute>,
         pub label: Option<Label>,
         pub for_token: Token![for],
         pub pat: Pat,
         pub in_token: Token![in],
         pub expr: Box<Expr>,
         pub body: Block,
@@ -416,538 +419,312 @@ ast_struct! {
 
 ast_struct! {
     /// An expression contained within invisible delimiters.
     ///
     /// This variant is important for faithfully representing the precedence
     /// of expressions and is related to `None`-delimited spans in a
     /// `TokenStream`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprGroup #full {
         pub attrs: Vec<Attribute>,
         pub group_token: token::Group,
         pub expr: Box<Expr>,
     }
 }
 
 ast_struct! {
     /// An `if` expression with an optional `else` block: `if expr { ... }
     /// else { ... }`.
     ///
     /// The `else` branch expression may only be an `If` or `Block`
     /// expression, not any of the other types of expression.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprIf #full {
         pub attrs: Vec<Attribute>,
         pub if_token: Token![if],
         pub cond: Box<Expr>,
         pub then_branch: Block,
         pub else_branch: Option<(Token![else], Box<Expr>)>,
     }
 }
 
 ast_struct! {
     /// A square bracketed indexing expression: `vector[2]`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct ExprIndex {
         pub attrs: Vec<Attribute>,
         pub expr: Box<Expr>,
         pub bracket_token: token::Bracket,
         pub index: Box<Expr>,
     }
 }
 
 ast_struct! {
     /// A `let` guard: `let Some(x) = opt`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprLet #full {
         pub attrs: Vec<Attribute>,
         pub let_token: Token![let],
         pub pat: Pat,
         pub eq_token: Token![=],
         pub expr: Box<Expr>,
     }
 }
 
 ast_struct! {
     /// A literal in place of an expression: `1`, `"foo"`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct ExprLit {
         pub attrs: Vec<Attribute>,
         pub lit: Lit,
     }
 }
 
 ast_struct! {
     /// Conditionless loop: `loop { ... }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprLoop #full {
         pub attrs: Vec<Attribute>,
         pub label: Option<Label>,
         pub loop_token: Token![loop],
         pub body: Block,
     }
 }
 
 ast_struct! {
     /// A macro invocation expression: `format!("{}", q)`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprMacro #full {
         pub attrs: Vec<Attribute>,
         pub mac: Macro,
     }
 }
 
 ast_struct! {
     /// A `match` expression: `match n { Some(n) => {}, None => {} }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprMatch #full {
         pub attrs: Vec<Attribute>,
         pub match_token: Token![match],
         pub expr: Box<Expr>,
         pub brace_token: token::Brace,
         pub arms: Vec<Arm>,
     }
 }
 
 ast_struct! {
     /// A method call expression: `x.foo::<T>(a, b)`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprMethodCall #full {
         pub attrs: Vec<Attribute>,
         pub receiver: Box<Expr>,
         pub dot_token: Token![.],
         pub method: Ident,
         pub turbofish: Option<MethodTurbofish>,
         pub paren_token: token::Paren,
         pub args: Punctuated<Expr, Token![,]>,
     }
 }
 
 ast_struct! {
     /// A parenthesized expression: `(a + b)`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprParen {
         pub attrs: Vec<Attribute>,
         pub paren_token: token::Paren,
         pub expr: Box<Expr>,
     }
 }
 
 ast_struct! {
     /// A path like `std::mem::replace` possibly containing generic
     /// parameters and a qualified self-type.
     ///
     /// A plain identifier like `x` is a path of length 1.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct ExprPath {
         pub attrs: Vec<Attribute>,
         pub qself: Option<QSelf>,
         pub path: Path,
     }
 }
 
 ast_struct! {
     /// A range expression: `1..2`, `1..`, `..2`, `1..=2`, `..=2`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprRange #full {
         pub attrs: Vec<Attribute>,
         pub from: Option<Box<Expr>>,
         pub limits: RangeLimits,
         pub to: Option<Box<Expr>>,
     }
 }
 
 ast_struct! {
     /// A referencing operation: `&a` or `&mut a`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprReference #full {
         pub attrs: Vec<Attribute>,
         pub and_token: Token![&],
         pub raw: Reserved,
         pub mutability: Option<Token![mut]>,
         pub expr: Box<Expr>,
     }
 }
 
 ast_struct! {
     /// An array literal constructed from one repeated element: `[0u8; N]`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprRepeat #full {
         pub attrs: Vec<Attribute>,
         pub bracket_token: token::Bracket,
         pub expr: Box<Expr>,
         pub semi_token: Token![;],
         pub len: Box<Expr>,
     }
 }
 
 ast_struct! {
     /// A `return`, with an optional value to be returned.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprReturn #full {
         pub attrs: Vec<Attribute>,
         pub return_token: Token![return],
         pub expr: Option<Box<Expr>>,
     }
 }
 
 ast_struct! {
     /// A struct literal expression: `Point { x: 1, y: 1 }`.
     ///
     /// The `rest` provides the value of the remaining fields as in `S { a:
     /// 1, b: 1, ..rest }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprStruct #full {
         pub attrs: Vec<Attribute>,
         pub path: Path,
         pub brace_token: token::Brace,
         pub fields: Punctuated<FieldValue, Token![,]>,
         pub dot2_token: Option<Token![..]>,
         pub rest: Option<Box<Expr>>,
     }
 }
 
 ast_struct! {
     /// A try-expression: `expr?`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprTry #full {
         pub attrs: Vec<Attribute>,
         pub expr: Box<Expr>,
         pub question_token: Token![?],
     }
 }
 
 ast_struct! {
     /// A try block: `try { ... }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprTryBlock #full {
         pub attrs: Vec<Attribute>,
         pub try_token: Token![try],
         pub block: Block,
     }
 }
 
 ast_struct! {
     /// A tuple expression: `(a, b, c, d)`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprTuple #full {
         pub attrs: Vec<Attribute>,
         pub paren_token: token::Paren,
         pub elems: Punctuated<Expr, Token![,]>,
     }
 }
 
 ast_struct! {
     /// A type ascription expression: `foo: f64`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprType #full {
         pub attrs: Vec<Attribute>,
         pub expr: Box<Expr>,
         pub colon_token: Token![:],
         pub ty: Box<Type>,
     }
 }
 
 ast_struct! {
     /// A unary operation: `!x`, `*x`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct ExprUnary {
         pub attrs: Vec<Attribute>,
         pub op: UnOp,
         pub expr: Box<Expr>,
     }
 }
 
 ast_struct! {
     /// An unsafe block: `unsafe { ... }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprUnsafe #full {
         pub attrs: Vec<Attribute>,
         pub unsafe_token: Token![unsafe],
         pub block: Block,
     }
 }
 
 ast_struct! {
     /// A while loop: `while expr { ... }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprWhile #full {
         pub attrs: Vec<Attribute>,
         pub label: Option<Label>,
         pub while_token: Token![while],
         pub cond: Box<Expr>,
         pub body: Block,
     }
 }
 
 ast_struct! {
     /// A yield expression: `yield expr`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ExprYield #full {
         pub attrs: Vec<Attribute>,
         pub yield_token: Token![yield],
         pub expr: Option<Box<Expr>>,
     }
 }
 
-#[cfg(feature = "extra-traits")]
-impl Eq for Expr {}
-
-#[cfg(feature = "extra-traits")]
-impl PartialEq for Expr {
-    fn eq(&self, other: &Self) -> bool {
-        match (self, other) {
-            (Expr::Array(this), Expr::Array(other)) => this == other,
-            (Expr::Assign(this), Expr::Assign(other)) => this == other,
-            (Expr::AssignOp(this), Expr::AssignOp(other)) => this == other,
-            (Expr::Async(this), Expr::Async(other)) => this == other,
-            (Expr::Await(this), Expr::Await(other)) => this == other,
-            (Expr::Binary(this), Expr::Binary(other)) => this == other,
-            (Expr::Block(this), Expr::Block(other)) => this == other,
-            (Expr::Box(this), Expr::Box(other)) => this == other,
-            (Expr::Break(this), Expr::Break(other)) => this == other,
-            (Expr::Call(this), Expr::Call(other)) => this == other,
-            (Expr::Cast(this), Expr::Cast(other)) => this == other,
-            (Expr::Closure(this), Expr::Closure(other)) => this == other,
-            (Expr::Continue(this), Expr::Continue(other)) => this == other,
-            (Expr::Field(this), Expr::Field(other)) => this == other,
-            (Expr::ForLoop(this), Expr::ForLoop(other)) => this == other,
-            (Expr::Group(this), Expr::Group(other)) => this == other,
-            (Expr::If(this), Expr::If(other)) => this == other,
-            (Expr::Index(this), Expr::Index(other)) => this == other,
-            (Expr::Let(this), Expr::Let(other)) => this == other,
-            (Expr::Lit(this), Expr::Lit(other)) => this == other,
-            (Expr::Loop(this), Expr::Loop(other)) => this == other,
-            (Expr::Macro(this), Expr::Macro(other)) => this == other,
-            (Expr::Match(this), Expr::Match(other)) => this == other,
-            (Expr::MethodCall(this), Expr::MethodCall(other)) => this == other,
-            (Expr::Paren(this), Expr::Paren(other)) => this == other,
-            (Expr::Path(this), Expr::Path(other)) => this == other,
-            (Expr::Range(this), Expr::Range(other)) => this == other,
-            (Expr::Reference(this), Expr::Reference(other)) => this == other,
-            (Expr::Repeat(this), Expr::Repeat(other)) => this == other,
-            (Expr::Return(this), Expr::Return(other)) => this == other,
-            (Expr::Struct(this), Expr::Struct(other)) => this == other,
-            (Expr::Try(this), Expr::Try(other)) => this == other,
-            (Expr::TryBlock(this), Expr::TryBlock(other)) => this == other,
-            (Expr::Tuple(this), Expr::Tuple(other)) => this == other,
-            (Expr::Type(this), Expr::Type(other)) => this == other,
-            (Expr::Unary(this), Expr::Unary(other)) => this == other,
-            (Expr::Unsafe(this), Expr::Unsafe(other)) => this == other,
-            (Expr::Verbatim(this), Expr::Verbatim(other)) => {
-                TokenStreamHelper(this) == TokenStreamHelper(other)
-            }
-            (Expr::While(this), Expr::While(other)) => this == other,
-            (Expr::Yield(this), Expr::Yield(other)) => this == other,
-            _ => false,
-        }
-    }
-}
-
-#[cfg(feature = "extra-traits")]
-impl Hash for Expr {
-    fn hash<H>(&self, hash: &mut H)
-    where
-        H: Hasher,
-    {
-        match self {
-            Expr::Array(expr) => {
-                hash.write_u8(0);
-                expr.hash(hash);
-            }
-            Expr::Assign(expr) => {
-                hash.write_u8(1);
-                expr.hash(hash);
-            }
-            Expr::AssignOp(expr) => {
-                hash.write_u8(2);
-                expr.hash(hash);
-            }
-            Expr::Async(expr) => {
-                hash.write_u8(3);
-                expr.hash(hash);
-            }
-            Expr::Await(expr) => {
-                hash.write_u8(4);
-                expr.hash(hash);
-            }
-            Expr::Binary(expr) => {
-                hash.write_u8(5);
-                expr.hash(hash);
-            }
-            Expr::Block(expr) => {
-                hash.write_u8(6);
-                expr.hash(hash);
-            }
-            Expr::Box(expr) => {
-                hash.write_u8(7);
-                expr.hash(hash);
-            }
-            Expr::Break(expr) => {
-                hash.write_u8(8);
-                expr.hash(hash);
-            }
-            Expr::Call(expr) => {
-                hash.write_u8(9);
-                expr.hash(hash);
-            }
-            Expr::Cast(expr) => {
-                hash.write_u8(10);
-                expr.hash(hash);
-            }
-            Expr::Closure(expr) => {
-                hash.write_u8(11);
-                expr.hash(hash);
-            }
-            Expr::Continue(expr) => {
-                hash.write_u8(12);
-                expr.hash(hash);
-            }
-            Expr::Field(expr) => {
-                hash.write_u8(13);
-                expr.hash(hash);
-            }
-            Expr::ForLoop(expr) => {
-                hash.write_u8(14);
-                expr.hash(hash);
-            }
-            Expr::Group(expr) => {
-                hash.write_u8(15);
-                expr.hash(hash);
-            }
-            Expr::If(expr) => {
-                hash.write_u8(16);
-                expr.hash(hash);
-            }
-            Expr::Index(expr) => {
-                hash.write_u8(17);
-                expr.hash(hash);
-            }
-            Expr::Let(expr) => {
-                hash.write_u8(18);
-                expr.hash(hash);
-            }
-            Expr::Lit(expr) => {
-                hash.write_u8(19);
-                expr.hash(hash);
-            }
-            Expr::Loop(expr) => {
-                hash.write_u8(20);
-                expr.hash(hash);
-            }
-            Expr::Macro(expr) => {
-                hash.write_u8(21);
-                expr.hash(hash);
-            }
-            Expr::Match(expr) => {
-                hash.write_u8(22);
-                expr.hash(hash);
-            }
-            Expr::MethodCall(expr) => {
-                hash.write_u8(23);
-                expr.hash(hash);
-            }
-            Expr::Paren(expr) => {
-                hash.write_u8(24);
-                expr.hash(hash);
-            }
-            Expr::Path(expr) => {
-                hash.write_u8(25);
-                expr.hash(hash);
-            }
-            Expr::Range(expr) => {
-                hash.write_u8(26);
-                expr.hash(hash);
-            }
-            Expr::Reference(expr) => {
-                hash.write_u8(27);
-                expr.hash(hash);
-            }
-            Expr::Repeat(expr) => {
-                hash.write_u8(28);
-                expr.hash(hash);
-            }
-            Expr::Return(expr) => {
-                hash.write_u8(29);
-                expr.hash(hash);
-            }
-            Expr::Struct(expr) => {
-                hash.write_u8(30);
-                expr.hash(hash);
-            }
-            Expr::Try(expr) => {
-                hash.write_u8(31);
-                expr.hash(hash);
-            }
-            Expr::TryBlock(expr) => {
-                hash.write_u8(32);
-                expr.hash(hash);
-            }
-            Expr::Tuple(expr) => {
-                hash.write_u8(33);
-                expr.hash(hash);
-            }
-            Expr::Type(expr) => {
-                hash.write_u8(34);
-                expr.hash(hash);
-            }
-            Expr::Unary(expr) => {
-                hash.write_u8(35);
-                expr.hash(hash);
-            }
-            Expr::Unsafe(expr) => {
-                hash.write_u8(36);
-                expr.hash(hash);
-            }
-            Expr::Verbatim(expr) => {
-                hash.write_u8(37);
-                TokenStreamHelper(expr).hash(hash);
-            }
-            Expr::While(expr) => {
-                hash.write_u8(38);
-                expr.hash(hash);
-            }
-            Expr::Yield(expr) => {
-                hash.write_u8(39);
-                expr.hash(hash);
-            }
-            Expr::__Nonexhaustive => unreachable!(),
-        }
-    }
-}
-
 impl Expr {
     #[cfg(all(feature = "parsing", feature = "full"))]
     pub(crate) fn replace_attrs(&mut self, new: Vec<Attribute>) -> Vec<Attribute> {
         match self {
             Expr::Box(ExprBox { attrs, .. })
             | Expr::Array(ExprArray { attrs, .. })
             | Expr::Call(ExprCall { attrs, .. })
             | Expr::MethodCall(ExprMethodCall { attrs, .. })
@@ -991,107 +768,145 @@ impl Expr {
         }
     }
 }
 
 ast_enum! {
     /// A struct or tuple struct field accessed in a struct literal or field
     /// expression.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub enum Member {
         /// A named field like `self.x`.
         Named(Ident),
         /// An unnamed field like `self.0`.
         Unnamed(Index),
     }
 }
 
+impl Eq for Member {}
+
+impl PartialEq for Member {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (Member::Named(this), Member::Named(other)) => this == other,
+            (Member::Unnamed(this), Member::Unnamed(other)) => this == other,
+            _ => false,
+        }
+    }
+}
+
+impl Hash for Member {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        match self {
+            Member::Named(m) => m.hash(state),
+            Member::Unnamed(m) => m.hash(state),
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+impl IdentFragment for Member {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Member::Named(m) => Display::fmt(m, formatter),
+            Member::Unnamed(m) => Display::fmt(&m.index, formatter),
+        }
+    }
+
+    fn span(&self) -> Option<Span> {
+        match self {
+            Member::Named(m) => Some(m.span()),
+            Member::Unnamed(m) => Some(m.span),
+        }
+    }
+}
+
 ast_struct! {
     /// The index of an unnamed tuple struct field.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
-    pub struct Index #manual_extra_traits {
+    pub struct Index {
         pub index: u32,
         pub span: Span,
     }
 }
 
 impl From<usize> for Index {
     fn from(index: usize) -> Index {
         assert!(index < u32::max_value() as usize);
         Index {
             index: index as u32,
             span: Span::call_site(),
         }
     }
 }
 
-#[cfg(feature = "extra-traits")]
 impl Eq for Index {}
 
-#[cfg(feature = "extra-traits")]
 impl PartialEq for Index {
     fn eq(&self, other: &Self) -> bool {
         self.index == other.index
     }
 }
 
-#[cfg(feature = "extra-traits")]
 impl Hash for Index {
     fn hash<H: Hasher>(&self, state: &mut H) {
         self.index.hash(state);
     }
 }
 
-#[cfg(feature = "full")]
-ast_struct! {
-    #[derive(Default)]
-    pub struct Reserved {
-        private: (),
+#[cfg(feature = "printing")]
+impl IdentFragment for Index {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        Display::fmt(&self.index, formatter)
+    }
+
+    fn span(&self) -> Option<Span> {
+        Some(self.span)
     }
 }
 
 #[cfg(feature = "full")]
 ast_struct! {
     /// The `::<>` explicit type parameters passed to a method call:
     /// `parse::<u64>()`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct MethodTurbofish {
         pub colon2_token: Token![::],
         pub lt_token: Token![<],
         pub args: Punctuated<GenericMethodArgument, Token![,]>,
         pub gt_token: Token![>],
     }
 }
 
 #[cfg(feature = "full")]
 ast_enum! {
     /// An individual generic argument to a method, like `T`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub enum GenericMethodArgument {
         /// A type argument.
         Type(Type),
         /// A const expression. Must be inside of a block.
         ///
         /// NOTE: Identity expressions are represented as Type arguments, as
         /// they are indistinguishable syntactically.
         Const(Expr),
     }
 }
 
 #[cfg(feature = "full")]
 ast_struct! {
     /// A field-value pair in a struct literal.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct FieldValue {
         /// Attributes tagged on the field.
         pub attrs: Vec<Attribute>,
 
         /// Name or index of the field.
         pub member: Member,
 
         /// The colon in `Struct { x: x }`. If written in shorthand like
@@ -1102,17 +917,17 @@ ast_struct! {
         pub expr: Expr,
     }
 }
 
 #[cfg(feature = "full")]
 ast_struct! {
     /// A lifetime labeling a `for`, `while`, or `loop`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct Label {
         pub name: Lifetime,
         pub colon_token: Token![:],
     }
 }
 
 #[cfg(feature = "full")]
 ast_struct! {
@@ -1129,45 +944,44 @@ ast_struct! {
     ///     }
     ///     // ...
     ///     # _ => {}
     /// }
     /// #   false
     /// # }
     /// ```
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct Arm {
         pub attrs: Vec<Attribute>,
         pub pat: Pat,
         pub guard: Option<(Token![if], Box<Expr>)>,
         pub fat_arrow_token: Token![=>],
         pub body: Box<Expr>,
         pub comma: Option<Token![,]>,
     }
 }
 
 #[cfg(feature = "full")]
 ast_enum! {
     /// Limit types of a range, inclusive or exclusive.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
-    #[cfg_attr(feature = "clone-impls", derive(Copy))]
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub enum RangeLimits {
         /// Inclusive at the beginning, exclusive at the end.
         HalfOpen(Token![..]),
         /// Inclusive at the beginning and end.
         Closed(Token![..=]),
     }
 }
 
 #[cfg(any(feature = "parsing", feature = "printing"))]
 #[cfg(feature = "full")]
 pub(crate) fn requires_terminator(expr: &Expr) -> bool {
-    // see https://github.com/rust-lang/rust/blob/eb8f2586e/src/libsyntax/parse/classify.rs#L17-L37
+    // see https://github.com/rust-lang/rust/blob/2679c38fc/src/librustc_ast/util/classify.rs#L7-L25
     match *expr {
         Expr::Unsafe(..)
         | Expr::Block(..)
         | Expr::If(..)
         | Expr::Match(..)
         | Expr::While(..)
         | Expr::Loop(..)
         | Expr::ForLoop(..)
@@ -1178,26 +992,27 @@ pub(crate) fn requires_terminator(expr: 
 }
 
 #[cfg(feature = "parsing")]
 pub(crate) mod parsing {
     use super::*;
 
     use crate::parse::{Parse, ParseStream, Result};
     use crate::path;
+    use std::cmp::Ordering;
+
+    crate::custom_keyword!(raw);
 
     // When we're parsing expressions which occur before blocks, like in an if
     // statement's condition, we cannot parse a struct literal.
     //
     // Struct literals are ambiguous in certain positions
     // https://github.com/rust-lang/rfcs/pull/92
-    #[derive(Copy, Clone)]
     pub struct AllowStruct(bool);
 
-    #[derive(Copy, Clone, PartialEq, PartialOrd)]
     enum Precedence {
         Any,
         Assign,
         Range,
         Or,
         And,
         Compare,
         BitOr,
@@ -1241,19 +1056,131 @@ pub(crate) mod parsing {
     }
 
     impl Parse for Expr {
         fn parse(input: ParseStream) -> Result<Self> {
             ambiguous_expr(input, AllowStruct(true))
         }
     }
 
-    #[cfg(feature = "full")]
-    fn expr_no_struct(input: ParseStream) -> Result<Expr> {
-        ambiguous_expr(input, AllowStruct(false))
+    impl Expr {
+        /// An alternative to the primary `Expr::parse` parser (from the
+        /// [`Parse`] trait) for ambiguous syntactic positions in which a
+        /// trailing brace should not be taken as part of the expression.
+        ///
+        /// Rust grammar has an ambiguity where braces sometimes turn a path
+        /// expression into a struct initialization and sometimes do not. In the
+        /// following code, the expression `S {}` is one expression. Presumably
+        /// there is an empty struct `struct S {}` defined somewhere which it is
+        /// instantiating.
+        ///
+        /// ```
+        /// # struct S;
+        /// # impl std::ops::Deref for S {
+        /// #     type Target = bool;
+        /// #     fn deref(&self) -> &Self::Target {
+        /// #         &true
+        /// #     }
+        /// # }
+        /// let _ = *S {};
+        ///
+        /// // parsed by rustc as: `*(S {})`
+        /// ```
+        ///
+        /// We would want to parse the above using `Expr::parse` after the `=`
+        /// token.
+        ///
+        /// But in the following, `S {}` is *not* a struct init expression.
+        ///
+        /// ```
+        /// # const S: &bool = &true;
+        /// if *S {} {}
+        ///
+        /// // parsed by rustc as:
+        /// //
+        /// //    if (*S) {
+        /// //        /* empty block */
+        /// //    }
+        /// //    {
+        /// //        /* another empty block */
+        /// //    }
+        /// ```
+        ///
+        /// For that reason we would want to parse if-conditions using
+        /// `Expr::parse_without_eager_brace` after the `if` token. Same for
+        /// similar syntactic positions such as the condition expr after a
+        /// `while` token or the expr at the top of a `match`.
+        ///
+        /// The Rust grammar's choices around which way this ambiguity is
+        /// resolved at various syntactic positions is fairly arbitrary. Really
+        /// either parse behavior could work in most positions, and language
+        /// designers just decide each case based on which is more likely to be
+        /// what the programmer had in mind most of the time.
+        ///
+        /// ```
+        /// # struct S;
+        /// # fn doc() -> S {
+        /// if return S {} {}
+        /// # unreachable!()
+        /// # }
+        ///
+        /// // parsed by rustc as:
+        /// //
+        /// //    if (return (S {})) {
+        /// //    }
+        /// //
+        /// // but could equally well have been this other arbitrary choice:
+        /// //
+        /// //    if (return S) {
+        /// //    }
+        /// //    {}
+        /// ```
+        ///
+        /// Note the grammar ambiguity on trailing braces is distinct from
+        /// precedence and is not captured by assigning a precedence level to
+        /// the braced struct init expr in relation to other operators. This can
+        /// be illustrated by `return 0..S {}` vs `match 0..S {}`. The former
+        /// parses as `return (0..(S {}))` implying tighter precedence for
+        /// struct init than `..`, while the latter parses as `match (0..S) {}`
+        /// implying tighter precedence for `..` than struct init, a
+        /// contradiction.
+        #[cfg(feature = "full")]
+        pub fn parse_without_eager_brace(input: ParseStream) -> Result<Expr> {
+            ambiguous_expr(input, AllowStruct(false))
+        }
+    }
+
+    impl Copy for AllowStruct {}
+
+    impl Clone for AllowStruct {
+        fn clone(&self) -> Self {
+            *self
+        }
+    }
+
+    impl Copy for Precedence {}
+
+    impl Clone for Precedence {
+        fn clone(&self) -> Self {
+            *self
+        }
+    }
+
+    impl PartialEq for Precedence {
+        fn eq(&self, other: &Self) -> bool {
+            *self as u8 == *other as u8
+        }
+    }
+
+    impl PartialOrd for Precedence {
+        fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+            let this = *self as u8;
+            let other = *other as u8;
+            Some(this.cmp(&other))
+        }
     }
 
     #[cfg(feature = "full")]
     fn parse_expr(
         input: ParseStream,
         mut lhs: Expr,
         allow_struct: AllowStruct,
         base: Precedence,
@@ -1425,88 +1352,114 @@ pub(crate) mod parsing {
     }
 
     // Parse an arbitrary expression.
     fn ambiguous_expr(input: ParseStream, allow_struct: AllowStruct) -> Result<Expr> {
         let lhs = unary_expr(input, allow_struct)?;
         parse_expr(input, lhs, allow_struct, Precedence::Any)
     }
 
+    #[cfg(feature = "full")]
+    fn expr_attrs(input: ParseStream) -> Result<Vec<Attribute>> {
+        let mut attrs = Vec::new();
+        loop {
+            if input.peek(token::Group) {
+                let ahead = input.fork();
+                let group = crate::group::parse_group(&ahead)?;
+                if !group.content.peek(Token![#]) || group.content.peek2(Token![!]) {
+                    break;
+                }
+                let attr = group.content.call(attr::parsing::single_parse_outer)?;
+                if !group.content.is_empty() {
+                    break;
+                }
+                attrs.push(attr);
+            } else if input.peek(Token![#]) {
+                attrs.push(input.call(attr::parsing::single_parse_outer)?);
+            } else {
+                break;
+            }
+        }
+        Ok(attrs)
+    }
+
     // <UnOp> <trailer>
     // & <trailer>
     // &mut <trailer>
     // box <trailer>
     #[cfg(feature = "full")]
     fn unary_expr(input: ParseStream, allow_struct: AllowStruct) -> Result<Expr> {
-        // TODO: optimize using advance_to
-        let ahead = input.fork();
-        ahead.call(Attribute::parse_outer)?;
-        if ahead.peek(Token![&])
-            || ahead.peek(Token![box])
-            || ahead.peek(Token![*])
-            || ahead.peek(Token![!])
-            || ahead.peek(Token![-])
-        {
-            let attrs = input.call(Attribute::parse_outer)?;
-            if input.peek(Token![&]) {
+        let begin = input.fork();
+        let attrs = input.call(expr_attrs)?;
+        if input.peek(Token![&]) {
+            let and_token: Token![&] = input.parse()?;
+            let raw: Option<raw> =
+                if input.peek(raw) && (input.peek2(Token![mut]) || input.peek2(Token![const])) {
+                    Some(input.parse()?)
+                } else {
+                    None
+                };
+            let mutability: Option<Token![mut]> = input.parse()?;
+            if raw.is_some() && mutability.is_none() {
+                input.parse::<Token![const]>()?;
+            }
+            let expr = Box::new(unary_expr(input, allow_struct)?);
+            if raw.is_some() {
+                Ok(Expr::Verbatim(verbatim::between(begin, input)))
+            } else {
                 Ok(Expr::Reference(ExprReference {
                     attrs,
-                    and_token: input.parse()?,
+                    and_token,
                     raw: Reserved::default(),
-                    mutability: input.parse()?,
-                    expr: Box::new(unary_expr(input, allow_struct)?),
-                }))
-            } else if input.peek(Token![box]) {
-                Ok(Expr::Box(ExprBox {
-                    attrs,
-                    box_token: input.parse()?,
-                    expr: Box::new(unary_expr(input, allow_struct)?),
-                }))
-            } else {
-                Ok(Expr::Unary(ExprUnary {
-                    attrs,
-                    op: input.parse()?,
-                    expr: Box::new(unary_expr(input, allow_struct)?),
+                    mutability,
+                    expr,
                 }))
             }
+        } else if input.peek(Token![box]) {
+            Ok(Expr::Box(ExprBox {
+                attrs,
+                box_token: input.parse()?,
+                expr: Box::new(unary_expr(input, allow_struct)?),
+            }))
+        } else if input.peek(Token![*]) || input.peek(Token![!]) || input.peek(Token![-]) {
+            Ok(Expr::Unary(ExprUnary {
+                attrs,
+                op: input.parse()?,
+                expr: Box::new(unary_expr(input, allow_struct)?),
+            }))
         } else {
-            trailer_expr(input, allow_struct)
+            trailer_expr(attrs, input, allow_struct)
         }
     }
 
     #[cfg(not(feature = "full"))]
     fn unary_expr(input: ParseStream, allow_struct: AllowStruct) -> Result<Expr> {
-        // TODO: optimize using advance_to
-        let ahead = input.fork();
-        ahead.call(Attribute::parse_outer)?;
-        if ahead.peek(Token![*]) || ahead.peek(Token![!]) || ahead.peek(Token![-]) {
+        if input.peek(Token![*]) || input.peek(Token![!]) || input.peek(Token![-]) {
             Ok(Expr::Unary(ExprUnary {
-                attrs: input.call(Attribute::parse_outer)?,
+                attrs: Vec::new(),
                 op: input.parse()?,
                 expr: Box::new(unary_expr(input, allow_struct)?),
             }))
         } else {
             trailer_expr(input, allow_struct)
         }
     }
 
     // <atom> (..<args>) ...
     // <atom> . <ident> (..<args>) ...
     // <atom> . <ident> ...
     // <atom> . <lit> ...
     // <atom> [ <expr> ] ...
     // <atom> ? ...
     #[cfg(feature = "full")]
-    fn trailer_expr(input: ParseStream, allow_struct: AllowStruct) -> Result<Expr> {
-        if input.peek(token::Group) {
-            return input.call(expr_group).map(Expr::Group);
-        }
-
-        let outer_attrs = input.call(Attribute::parse_outer)?;
-
+    fn trailer_expr(
+        outer_attrs: Vec<Attribute>,
+        input: ParseStream,
+        allow_struct: AllowStruct,
+    ) -> Result<Expr> {
         let atom = atom_expr(input, allow_struct)?;
         let mut e = trailer_helper(input, atom)?;
 
         let inner_attrs = e.replace_attrs(Vec::new());
         let attrs = private::attrs(outer_attrs, inner_attrs);
         e.replace_attrs(attrs);
         Ok(e)
     }
@@ -1518,28 +1471,36 @@ pub(crate) mod parsing {
                 let content;
                 e = Expr::Call(ExprCall {
                     attrs: Vec::new(),
                     func: Box::new(e),
                     paren_token: parenthesized!(content in input),
                     args: content.parse_terminated(Expr::parse)?,
                 });
             } else if input.peek(Token![.]) && !input.peek(Token![..]) {
-                let dot_token: Token![.] = input.parse()?;
+                let mut dot_token: Token![.] = input.parse()?;
 
-                if input.peek(token::Await) {
+                let await_token: Option<token::Await> = input.parse()?;
+                if let Some(await_token) = await_token {
                     e = Expr::Await(ExprAwait {
                         attrs: Vec::new(),
                         base: Box::new(e),
                         dot_token,
-                        await_token: input.parse()?,
+                        await_token,
                     });
                     continue;
                 }
 
+                let float_token: Option<LitFloat> = input.parse()?;
+                if let Some(float_token) = float_token {
+                    if multi_index(&mut e, &mut dot_token, float_token)? {
+                        continue;
+                    }
+                }
+
                 let member: Member = input.parse()?;
                 let turbofish = if member.is_named() && input.peek(Token![::]) {
                     Some(MethodTurbofish {
                         colon2_token: input.parse()?,
                         lt_token: input.parse()?,
                         args: {
                             let mut args = Punctuated::new();
                             loop {
@@ -1615,20 +1576,27 @@ pub(crate) mod parsing {
                 e = Expr::Call(ExprCall {
                     attrs: Vec::new(),
                     func: Box::new(e),
                     paren_token: parenthesized!(content in input),
                     args: content.parse_terminated(Expr::parse)?,
                 });
             } else if input.peek(Token![.]) && !input.peek(Token![..]) && !input.peek2(token::Await)
             {
+                let mut dot_token: Token![.] = input.parse()?;
+                let float_token: Option<LitFloat> = input.parse()?;
+                if let Some(float_token) = float_token {
+                    if multi_index(&mut e, &mut dot_token, float_token)? {
+                        continue;
+                    }
+                }
                 e = Expr::Field(ExprField {
                     attrs: Vec::new(),
                     base: Box::new(e),
-                    dot_token: input.parse()?,
+                    dot_token,
                     member: input.parse()?,
                 });
             } else if input.peek(token::Bracket) {
                 let content;
                 e = Expr::Index(ExprIndex {
                     attrs: Vec::new(),
                     expr: Box::new(e),
                     bracket_token: bracketed!(content in input),
@@ -1641,17 +1609,21 @@ pub(crate) mod parsing {
 
         Ok(e)
     }
 
     // Parse all atomic expressions which don't have to worry about precedence
     // interactions, as they are fully contained.
     #[cfg(feature = "full")]
     fn atom_expr(input: ParseStream, allow_struct: AllowStruct) -> Result<Expr> {
-        if input.peek(token::Group) {
+        if input.peek(token::Group)
+            && !input.peek2(Token![::])
+            && !input.peek2(Token![!])
+            && !input.peek2(token::Brace)
+        {
             input.call(expr_group).map(Expr::Group)
         } else if input.peek(Lit) {
             input.parse().map(Expr::Lit)
         } else if input.peek(Token![async])
             && (input.peek2(token::Brace) || input.peek2(Token![move]) && input.peek3(token::Brace))
         {
             input.call(expr_async).map(Expr::Async)
         } else if input.peek(Token![try]) && input.peek2(token::Brace) {
@@ -1663,17 +1635,16 @@ pub(crate) mod parsing {
         {
             expr_closure(input, allow_struct).map(Expr::Closure)
         } else if input.peek(Ident)
             || input.peek(Token![::])
             || input.peek(Token![<])
             || input.peek(Token![self])
             || input.peek(Token![Self])
             || input.peek(Token![super])
-            || input.peek(Token![extern])
             || input.peek(Token![crate])
         {
             path_or_macro_or_struct(input, allow_struct)
         } else if input.peek(token::Paren) {
             paren_or_tuple(input)
         } else if input.peek(Token![break]) {
             expr_break(input, allow_struct).map(Expr::Break)
         } else if input.peek(Token![continue]) {
@@ -1735,17 +1706,16 @@ pub(crate) mod parsing {
         } else if input.peek(token::Paren) {
             input.call(expr_paren).map(Expr::Paren)
         } else if input.peek(Ident)
             || input.peek(Token![::])
             || input.peek(Token![<])
             || input.peek(Token![self])
             || input.peek(Token![Self])
             || input.peek(Token![super])
-            || input.peek(Token![extern])
             || input.peek(Token![crate])
         {
             input.parse().map(Expr::Path)
         } else {
             Err(input.error("unsupported expression; enable syn's features=[\"full\"]"))
         }
     }
 
@@ -1873,17 +1843,17 @@ pub(crate) mod parsing {
             }))
         } else {
             Err(content.error("expected `,` or `;`"))
         }
     }
 
     #[cfg(feature = "full")]
     pub(crate) fn expr_early(input: ParseStream) -> Result<Expr> {
-        let mut attrs = input.call(Attribute::parse_outer)?;
+        let mut attrs = input.call(expr_attrs)?;
         let mut expr = if input.peek(Token![if]) {
             Expr::If(input.parse()?)
         } else if input.peek(Token![while]) {
             Expr::While(input.parse()?)
         } else if input.peek(Token![for]) {
             Expr::ForLoop(input.parse()?)
         } else if input.peek(Token![loop]) {
             Expr::Loop(input.parse()?)
@@ -1900,17 +1870,17 @@ pub(crate) mod parsing {
             let mut expr = unary_expr(input, allow_struct)?;
 
             attrs.extend(expr.replace_attrs(Vec::new()));
             expr.replace_attrs(attrs);
 
             return parse_expr(input, expr, allow_struct, Precedence::Any);
         };
 
-        if input.peek(Token![.]) || input.peek(Token![?]) {
+        if input.peek(Token![.]) && !input.peek(Token![..]) || input.peek(Token![?]) {
             expr = trailer_helper(input, expr)?;
 
             attrs.extend(expr.replace_attrs(Vec::new()));
             expr.replace_attrs(attrs);
 
             let allow_struct = AllowStruct(true);
             return parse_expr(input, expr, allow_struct, Precedence::Any);
         }
@@ -1946,63 +1916,48 @@ pub(crate) mod parsing {
             attrs: Vec::new(),
             paren_token: parenthesized!(content in input),
             expr: content.parse()?,
         })
     }
 
     #[cfg(feature = "full")]
     fn generic_method_argument(input: ParseStream) -> Result<GenericMethodArgument> {
-        // TODO parse const generics as well
+        if input.peek(Lit) {
+            let lit = input.parse()?;
+            return Ok(GenericMethodArgument::Const(Expr::Lit(lit)));
+        }
+
+        if input.peek(token::Brace) {
+            let block = input.call(expr::parsing::expr_block)?;
+            return Ok(GenericMethodArgument::Const(Expr::Block(block)));
+        }
+
         input.parse().map(GenericMethodArgument::Type)
     }
 
     #[cfg(feature = "full")]
     fn expr_let(input: ParseStream) -> Result<ExprLet> {
         Ok(ExprLet {
             attrs: Vec::new(),
             let_token: input.parse()?,
-            pat: {
-                let leading_vert: Option<Token![|]> = input.parse()?;
-                let pat: Pat = input.parse()?;
-                if leading_vert.is_some()
-                    || input.peek(Token![|]) && !input.peek(Token![||]) && !input.peek(Token![|=])
-                {
-                    let mut cases = Punctuated::new();
-                    cases.push_value(pat);
-                    while input.peek(Token![|])
-                        && !input.peek(Token![||])
-                        && !input.peek(Token![|=])
-                    {
-                        let punct = input.parse()?;
-                        cases.push_punct(punct);
-                        let pat: Pat = input.parse()?;
-                        cases.push_value(pat);
-                    }
-                    Pat::Or(PatOr {
-                        attrs: Vec::new(),
-                        leading_vert,
-                        cases,
-                    })
-                } else {
-                    pat
-                }
-            },
+            pat: pat::parsing::multi_pat_with_leading_vert(input)?,
             eq_token: input.parse()?,
-            expr: Box::new(input.call(expr_no_struct)?),
+            expr: Box::new(input.call(Expr::parse_without_eager_brace)?),
         })
     }
 
     #[cfg(feature = "full")]
     impl Parse for ExprIf {
         fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
             Ok(ExprIf {
-                attrs: Vec::new(),
+                attrs,
                 if_token: input.parse()?,
-                cond: Box::new(input.call(expr_no_struct)?),
+                cond: Box::new(input.call(Expr::parse_without_eager_brace)?),
                 then_branch: input.parse()?,
                 else_branch: {
                     if input.peek(Token![else]) {
                         Some(input.call(else_block)?)
                     } else {
                         None
                     }
                 },
@@ -2028,94 +1983,81 @@ pub(crate) mod parsing {
         };
 
         Ok((else_token, Box::new(else_branch)))
     }
 
     #[cfg(feature = "full")]
     impl Parse for ExprForLoop {
         fn parse(input: ParseStream) -> Result<Self> {
+            let outer_attrs = input.call(Attribute::parse_outer)?;
             let label: Option<Label> = input.parse()?;
             let for_token: Token![for] = input.parse()?;
 
-            let leading_vert: Option<Token![|]> = input.parse()?;
-            let mut pat: Pat = input.parse()?;
-            if leading_vert.is_some() || input.peek(Token![|]) {
-                let mut cases = Punctuated::new();
-                cases.push_value(pat);
-                while input.peek(Token![|]) {
-                    let punct = input.parse()?;
-                    cases.push_punct(punct);
-                    let pat: Pat = input.parse()?;
-                    cases.push_value(pat);
-                }
-                pat = Pat::Or(PatOr {
-                    attrs: Vec::new(),
-                    leading_vert,
-                    cases,
-                });
-            }
+            let pat = pat::parsing::multi_pat_with_leading_vert(input)?;
 
             let in_token: Token![in] = input.parse()?;
-            let expr: Expr = input.call(expr_no_struct)?;
+            let expr: Expr = input.call(Expr::parse_without_eager_brace)?;
 
             let content;
             let brace_token = braced!(content in input);
             let inner_attrs = content.call(Attribute::parse_inner)?;
             let stmts = content.call(Block::parse_within)?;
 
             Ok(ExprForLoop {
-                attrs: inner_attrs,
+                attrs: private::attrs(outer_attrs, inner_attrs),
                 label,
                 for_token,
                 pat,
                 in_token,
                 expr: Box::new(expr),
                 body: Block { brace_token, stmts },
             })
         }
     }
 
     #[cfg(feature = "full")]
     impl Parse for ExprLoop {
         fn parse(input: ParseStream) -> Result<Self> {
+            let outer_attrs = input.call(Attribute::parse_outer)?;
             let label: Option<Label> = input.parse()?;
             let loop_token: Token![loop] = input.parse()?;
 
             let content;
             let brace_token = braced!(content in input);
             let inner_attrs = content.call(Attribute::parse_inner)?;
             let stmts = content.call(Block::parse_within)?;
 
             Ok(ExprLoop {
-                attrs: inner_attrs,
+                attrs: private::attrs(outer_attrs, inner_attrs),
                 label,
                 loop_token,
                 body: Block { brace_token, stmts },
             })
         }
     }
 
     #[cfg(feature = "full")]
     impl Parse for ExprMatch {
         fn parse(input: ParseStream) -> Result<Self> {
+            let outer_attrs = input.call(Attribute::parse_outer)?;
             let match_token: Token![match] = input.parse()?;
-            let expr = expr_no_struct(input)?;
+            let expr = Expr::parse_without_eager_brace(input)?;
 
             let content;
             let brace_token = braced!(content in input);
             let inner_attrs = content.call(Attribute::parse_inner)?;
 
             let mut arms = Vec::new();
             while !content.is_empty() {
                 arms.push(content.call(Arm::parse)?);
             }
 
             Ok(ExprMatch {
-                attrs: inner_attrs,
+                attrs: private::attrs(outer_attrs, inner_attrs),
                 match_token,
                 expr: Box::new(expr),
                 brace_token,
                 arms,
             })
         }
     }
 
@@ -2300,27 +2242,28 @@ pub(crate) mod parsing {
             }
             Ok(pat)
         }
     }
 
     #[cfg(feature = "full")]
     impl Parse for ExprWhile {
         fn parse(input: ParseStream) -> Result<Self> {
+            let outer_attrs = input.call(Attribute::parse_outer)?;
             let label: Option<Label> = input.parse()?;
             let while_token: Token![while] = input.parse()?;
-            let cond = expr_no_struct(input)?;
+            let cond = Expr::parse_without_eager_brace(input)?;
 
             let content;
             let brace_token = braced!(content in input);
             let inner_attrs = content.call(Attribute::parse_inner)?;
             let stmts = content.call(Block::parse_within)?;
 
             Ok(ExprWhile {
-                attrs: inner_attrs,
+                attrs: private::attrs(outer_attrs, inner_attrs),
                 label,
                 while_token,
                 cond: Box::new(cond),
                 body: Block { brace_token, stmts },
             })
         }
     }
 
@@ -2394,16 +2337,17 @@ pub(crate) mod parsing {
                 }
             },
         })
     }
 
     #[cfg(feature = "full")]
     impl Parse for FieldValue {
         fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
             let member: Member = input.parse()?;
             let (colon_token, value) = if input.peek(Token![:]) || !member.is_named() {
                 let colon_token: Token![:] = input.parse()?;
                 let value: Expr = input.parse()?;
                 (Some(colon_token), value)
             } else if let Member::Named(ident) = &member {
                 let value = Expr::Path(ExprPath {
                     attrs: Vec::new(),
@@ -2411,73 +2355,63 @@ pub(crate) mod parsing {
                     path: Path::from(ident.clone()),
                 });
                 (None, value)
             } else {
                 unreachable!()
             };
 
             Ok(FieldValue {
-                attrs: Vec::new(),
+                attrs,
                 member,
                 colon_token,
                 expr: value,
             })
         }
     }
 
     #[cfg(feature = "full")]
     fn expr_struct_helper(
         input: ParseStream,
         outer_attrs: Vec<Attribute>,
         path: Path,
     ) -> Result<ExprStruct> {
         let content;
         let brace_token = braced!(content in input);
         let inner_attrs = content.call(Attribute::parse_inner)?;
+        let attrs = private::attrs(outer_attrs, inner_attrs);
 
         let mut fields = Punctuated::new();
-        loop {
-            let attrs = content.call(Attribute::parse_outer)?;
-            // TODO: optimize using advance_to
-            if content.fork().parse::<Member>().is_err() {
-                if attrs.is_empty() {
-                    break;
-                } else {
-                    return Err(content.error("expected struct field"));
-                }
+        while !content.is_empty() {
+            if content.peek(Token![..]) {
+                return Ok(ExprStruct {
+                    attrs,
+                    brace_token,
+                    path,
+                    fields,
+                    dot2_token: Some(content.parse()?),
+                    rest: Some(Box::new(content.parse()?)),
+                });
             }
 
-            fields.push(FieldValue {
-                attrs,
-                ..content.parse()?
-            });
-
-            if !content.peek(Token![,]) {
+            fields.push(content.parse()?);
+            if content.is_empty() {
                 break;
             }
             let punct: Token![,] = content.parse()?;
             fields.push_punct(punct);
         }
 
-        let (dot2_token, rest) = if fields.empty_or_trailing() && content.peek(Token![..]) {
-            let dot2_token: Token![..] = content.parse()?;
-            let rest: Expr = content.parse()?;
-            (Some(dot2_token), Some(Box::new(rest)))
-        } else {
-            (None, None)
-        };
-
         Ok(ExprStruct {
-            attrs: private::attrs(outer_attrs, inner_attrs),
+            attrs,
             brace_token,
             path,
             fields,
-            dot2_token,
-            rest,
+            dot2_token: None,
+            rest: None,
         })
     }
 
     #[cfg(feature = "full")]
     fn expr_unsafe(input: ParseStream) -> Result<ExprUnsafe> {
         let unsafe_token: Token![unsafe] = input.parse()?;
 
         let content;
@@ -2572,37 +2506,17 @@ pub(crate) mod parsing {
     }
 
     #[cfg(feature = "full")]
     impl Parse for Arm {
         fn parse(input: ParseStream) -> Result<Arm> {
             let requires_comma;
             Ok(Arm {
                 attrs: input.call(Attribute::parse_outer)?,
-                pat: {
-                    let leading_vert: Option<Token![|]> = input.parse()?;
-                    let pat: Pat = input.parse()?;
-                    if leading_vert.is_some() || input.peek(Token![|]) {
-                        let mut cases = Punctuated::new();
-                        cases.push_value(pat);
-                        while input.peek(Token![|]) {
-                            let punct = input.parse()?;
-                            cases.push_punct(punct);
-                            let pat: Pat = input.parse()?;
-                            cases.push_value(pat);
-                        }
-                        Pat::Or(PatOr {
-                            attrs: Vec::new(),
-                            leading_vert,
-                            cases,
-                        })
-                    } else {
-                        pat
-                    }
-                },
+                pat: pat::parsing::multi_pat_with_leading_vert(input)?,
                 guard: {
                     if input.peek(Token![if]) {
                         let if_token: Token![if] = input.parse()?;
                         let guard: Expr = input.parse()?;
                         Some((if_token, Box::new(guard)))
                     } else {
                         None
                     }
@@ -2636,16 +2550,36 @@ pub(crate) mod parsing {
                     span: lit.span(),
                 })
             } else {
                 Err(Error::new(lit.span(), "expected unsuffixed integer"))
             }
         }
     }
 
+    fn multi_index(e: &mut Expr, dot_token: &mut Token![.], float: LitFloat) -> Result<bool> {
+        let mut float_repr = float.to_string();
+        let trailing_dot = float_repr.ends_with('.');
+        if trailing_dot {
+            float_repr.truncate(float_repr.len() - 1);
+        }
+        for part in float_repr.split('.') {
+            let index = crate::parse_str(part).map_err(|err| Error::new(float.span(), err))?;
+            let base = mem::replace(e, Expr::__Nonexhaustive);
+            *e = Expr::Field(ExprField {
+                attrs: Vec::new(),
+                base: Box::new(base),
+                dot_token: Token![.](dot_token.span),
+                member: Member::Unnamed(index),
+            });
+            *dot_token = Token![.](float.span());
+        }
+        Ok(!trailing_dot)
+    }
+
     #[cfg(feature = "full")]
     impl Member {
         fn is_named(&self) -> bool {
             match *self {
                 Member::Named(_) => true,
                 Member::Unnamed(_) => false,
             }
         }
diff --git a/third_party/rust/syn/src/ext.rs b/third_party/rust/syn/src/ext.rs
--- a/third_party/rust/syn/src/ext.rs
+++ b/third_party/rust/syn/src/ext.rs
@@ -1,27 +1,27 @@
 //! Extension traits to provide parsing methods on foreign types.
 //!
-//! *This module is available if Syn is built with the `"parsing"` feature.*
+//! *This module is available only if Syn is built with the `"parsing"` feature.*
 
 use proc_macro2::Ident;
 
 use crate::parse::{ParseStream, Result};
 
 use crate::buffer::Cursor;
 use crate::parse::Peek;
 use crate::sealed::lookahead;
 use crate::token::CustomToken;
 
 /// Additional methods for `Ident` not provided by proc-macro2 or libproc_macro.
 ///
 /// This trait is sealed and cannot be implemented for types outside of Syn. It
 /// is implemented only for `proc_macro2::Ident`.
 ///
-/// *This trait is available if Syn is built with the `"parsing"` feature.*
+/// *This trait is available only if Syn is built with the `"parsing"` feature.*
 pub trait IdentExt: Sized + private::Sealed {
     /// Parses any identifier including keywords.
     ///
     /// This is useful when parsing macro input which allows Rust keywords as
     /// identifiers.
     ///
     /// # Example
     ///
@@ -124,12 +124,18 @@ impl lookahead::Sealed for private::Peek
 
 mod private {
     use proc_macro2::Ident;
 
     pub trait Sealed {}
 
     impl Sealed for Ident {}
 
-    #[derive(Copy, Clone)]
     pub struct PeekFn;
     pub struct IdentAny;
+
+    impl Copy for PeekFn {}
+    impl Clone for PeekFn {
+        fn clone(&self) -> Self {
+            *self
+        }
+    }
 }
diff --git a/third_party/rust/syn/src/file.rs b/third_party/rust/syn/src/file.rs
--- a/third_party/rust/syn/src/file.rs
+++ b/third_party/rust/syn/src/file.rs
@@ -1,14 +1,14 @@
 use super::*;
 
 ast_struct! {
     /// A complete file of Rust source code.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     ///
     /// # Example
     ///
     /// Parse a Rust source file into a `syn::File` and print out a debug
     /// representation of the syntax tree.
     ///
     /// ```
     /// use std::env;
@@ -32,16 +32,18 @@ ast_struct! {
     ///     };
     ///
     ///     let mut file = File::open(&filename).expect("Unable to open file");
     ///
     ///     let mut src = String::new();
     ///     file.read_to_string(&mut src).expect("Unable to read file");
     ///
     ///     let syntax = syn::parse_file(&src).expect("Unable to parse file");
+    ///
+    ///     // Debug impl is available if Syn is built with "extra-traits" feature.
     ///     println!("{:#?}", syntax);
     /// }
     /// ```
     ///
     /// Running with its own source code as input, this program prints output
     /// that begins with:
     ///
     /// ```text
diff --git a/third_party/rust/syn/src/gen/clone.rs b/third_party/rust/syn/src/gen/clone.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/src/gen/clone.rs
@@ -0,0 +1,2051 @@
+// This file is @generated by syn-internal-codegen.
+// It is not intended for manual editing.
+
+#![allow(clippy::clone_on_copy, clippy::expl_impl_clone_on_copy)]
+use crate::*;
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Abi {
+    fn clone(&self) -> Self {
+        Abi {
+            extern_token: self.extern_token.clone(),
+            name: self.name.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for AngleBracketedGenericArguments {
+    fn clone(&self) -> Self {
+        AngleBracketedGenericArguments {
+            colon2_token: self.colon2_token.clone(),
+            lt_token: self.lt_token.clone(),
+            args: self.args.clone(),
+            gt_token: self.gt_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for Arm {
+    fn clone(&self) -> Self {
+        Arm {
+            attrs: self.attrs.clone(),
+            pat: self.pat.clone(),
+            guard: self.guard.clone(),
+            fat_arrow_token: self.fat_arrow_token.clone(),
+            body: self.body.clone(),
+            comma: self.comma.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Copy for AttrStyle {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for AttrStyle {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Attribute {
+    fn clone(&self) -> Self {
+        Attribute {
+            pound_token: self.pound_token.clone(),
+            style: self.style.clone(),
+            bracket_token: self.bracket_token.clone(),
+            path: self.path.clone(),
+            tokens: self.tokens.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for BareFnArg {
+    fn clone(&self) -> Self {
+        BareFnArg {
+            attrs: self.attrs.clone(),
+            name: self.name.clone(),
+            ty: self.ty.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Copy for BinOp {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for BinOp {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Binding {
+    fn clone(&self) -> Self {
+        Binding {
+            ident: self.ident.clone(),
+            eq_token: self.eq_token.clone(),
+            ty: self.ty.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for Block {
+    fn clone(&self) -> Self {
+        Block {
+            brace_token: self.brace_token.clone(),
+            stmts: self.stmts.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for BoundLifetimes {
+    fn clone(&self) -> Self {
+        BoundLifetimes {
+            for_token: self.for_token.clone(),
+            lt_token: self.lt_token.clone(),
+            lifetimes: self.lifetimes.clone(),
+            gt_token: self.gt_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for ConstParam {
+    fn clone(&self) -> Self {
+        ConstParam {
+            attrs: self.attrs.clone(),
+            const_token: self.const_token.clone(),
+            ident: self.ident.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+            eq_token: self.eq_token.clone(),
+            default: self.default.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Constraint {
+    fn clone(&self) -> Self {
+        Constraint {
+            ident: self.ident.clone(),
+            colon_token: self.colon_token.clone(),
+            bounds: self.bounds.clone(),
+        }
+    }
+}
+#[cfg(feature = "derive")]
+impl Clone for Data {
+    fn clone(&self) -> Self {
+        match self {
+            Data::Struct(v0) => Data::Struct(v0.clone()),
+            Data::Enum(v0) => Data::Enum(v0.clone()),
+            Data::Union(v0) => Data::Union(v0.clone()),
+        }
+    }
+}
+#[cfg(feature = "derive")]
+impl Clone for DataEnum {
+    fn clone(&self) -> Self {
+        DataEnum {
+            enum_token: self.enum_token.clone(),
+            brace_token: self.brace_token.clone(),
+            variants: self.variants.clone(),
+        }
+    }
+}
+#[cfg(feature = "derive")]
+impl Clone for DataStruct {
+    fn clone(&self) -> Self {
+        DataStruct {
+            struct_token: self.struct_token.clone(),
+            fields: self.fields.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "derive")]
+impl Clone for DataUnion {
+    fn clone(&self) -> Self {
+        DataUnion {
+            union_token: self.union_token.clone(),
+            fields: self.fields.clone(),
+        }
+    }
+}
+#[cfg(feature = "derive")]
+impl Clone for DeriveInput {
+    fn clone(&self) -> Self {
+        DeriveInput {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            data: self.data.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Expr {
+    fn clone(&self) -> Self {
+        match self {
+            #[cfg(feature = "full")]
+            Expr::Array(v0) => Expr::Array(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Assign(v0) => Expr::Assign(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::AssignOp(v0) => Expr::AssignOp(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Async(v0) => Expr::Async(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Await(v0) => Expr::Await(v0.clone()),
+            Expr::Binary(v0) => Expr::Binary(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Block(v0) => Expr::Block(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Box(v0) => Expr::Box(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Break(v0) => Expr::Break(v0.clone()),
+            Expr::Call(v0) => Expr::Call(v0.clone()),
+            Expr::Cast(v0) => Expr::Cast(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Closure(v0) => Expr::Closure(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Continue(v0) => Expr::Continue(v0.clone()),
+            Expr::Field(v0) => Expr::Field(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::ForLoop(v0) => Expr::ForLoop(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Group(v0) => Expr::Group(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::If(v0) => Expr::If(v0.clone()),
+            Expr::Index(v0) => Expr::Index(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Let(v0) => Expr::Let(v0.clone()),
+            Expr::Lit(v0) => Expr::Lit(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Loop(v0) => Expr::Loop(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Macro(v0) => Expr::Macro(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Match(v0) => Expr::Match(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::MethodCall(v0) => Expr::MethodCall(v0.clone()),
+            Expr::Paren(v0) => Expr::Paren(v0.clone()),
+            Expr::Path(v0) => Expr::Path(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Range(v0) => Expr::Range(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Reference(v0) => Expr::Reference(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Repeat(v0) => Expr::Repeat(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Return(v0) => Expr::Return(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Struct(v0) => Expr::Struct(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Try(v0) => Expr::Try(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::TryBlock(v0) => Expr::TryBlock(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Tuple(v0) => Expr::Tuple(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Type(v0) => Expr::Type(v0.clone()),
+            Expr::Unary(v0) => Expr::Unary(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Unsafe(v0) => Expr::Unsafe(v0.clone()),
+            Expr::Verbatim(v0) => Expr::Verbatim(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::While(v0) => Expr::While(v0.clone()),
+            #[cfg(feature = "full")]
+            Expr::Yield(v0) => Expr::Yield(v0.clone()),
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprArray {
+    fn clone(&self) -> Self {
+        ExprArray {
+            attrs: self.attrs.clone(),
+            bracket_token: self.bracket_token.clone(),
+            elems: self.elems.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprAssign {
+    fn clone(&self) -> Self {
+        ExprAssign {
+            attrs: self.attrs.clone(),
+            left: self.left.clone(),
+            eq_token: self.eq_token.clone(),
+            right: self.right.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprAssignOp {
+    fn clone(&self) -> Self {
+        ExprAssignOp {
+            attrs: self.attrs.clone(),
+            left: self.left.clone(),
+            op: self.op.clone(),
+            right: self.right.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprAsync {
+    fn clone(&self) -> Self {
+        ExprAsync {
+            attrs: self.attrs.clone(),
+            async_token: self.async_token.clone(),
+            capture: self.capture.clone(),
+            block: self.block.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprAwait {
+    fn clone(&self) -> Self {
+        ExprAwait {
+            attrs: self.attrs.clone(),
+            base: self.base.clone(),
+            dot_token: self.dot_token.clone(),
+            await_token: self.await_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for ExprBinary {
+    fn clone(&self) -> Self {
+        ExprBinary {
+            attrs: self.attrs.clone(),
+            left: self.left.clone(),
+            op: self.op.clone(),
+            right: self.right.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprBlock {
+    fn clone(&self) -> Self {
+        ExprBlock {
+            attrs: self.attrs.clone(),
+            label: self.label.clone(),
+            block: self.block.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprBox {
+    fn clone(&self) -> Self {
+        ExprBox {
+            attrs: self.attrs.clone(),
+            box_token: self.box_token.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprBreak {
+    fn clone(&self) -> Self {
+        ExprBreak {
+            attrs: self.attrs.clone(),
+            break_token: self.break_token.clone(),
+            label: self.label.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for ExprCall {
+    fn clone(&self) -> Self {
+        ExprCall {
+            attrs: self.attrs.clone(),
+            func: self.func.clone(),
+            paren_token: self.paren_token.clone(),
+            args: self.args.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for ExprCast {
+    fn clone(&self) -> Self {
+        ExprCast {
+            attrs: self.attrs.clone(),
+            expr: self.expr.clone(),
+            as_token: self.as_token.clone(),
+            ty: self.ty.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprClosure {
+    fn clone(&self) -> Self {
+        ExprClosure {
+            attrs: self.attrs.clone(),
+            asyncness: self.asyncness.clone(),
+            movability: self.movability.clone(),
+            capture: self.capture.clone(),
+            or1_token: self.or1_token.clone(),
+            inputs: self.inputs.clone(),
+            or2_token: self.or2_token.clone(),
+            output: self.output.clone(),
+            body: self.body.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprContinue {
+    fn clone(&self) -> Self {
+        ExprContinue {
+            attrs: self.attrs.clone(),
+            continue_token: self.continue_token.clone(),
+            label: self.label.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for ExprField {
+    fn clone(&self) -> Self {
+        ExprField {
+            attrs: self.attrs.clone(),
+            base: self.base.clone(),
+            dot_token: self.dot_token.clone(),
+            member: self.member.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprForLoop {
+    fn clone(&self) -> Self {
+        ExprForLoop {
+            attrs: self.attrs.clone(),
+            label: self.label.clone(),
+            for_token: self.for_token.clone(),
+            pat: self.pat.clone(),
+            in_token: self.in_token.clone(),
+            expr: self.expr.clone(),
+            body: self.body.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprGroup {
+    fn clone(&self) -> Self {
+        ExprGroup {
+            attrs: self.attrs.clone(),
+            group_token: self.group_token.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprIf {
+    fn clone(&self) -> Self {
+        ExprIf {
+            attrs: self.attrs.clone(),
+            if_token: self.if_token.clone(),
+            cond: self.cond.clone(),
+            then_branch: self.then_branch.clone(),
+            else_branch: self.else_branch.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for ExprIndex {
+    fn clone(&self) -> Self {
+        ExprIndex {
+            attrs: self.attrs.clone(),
+            expr: self.expr.clone(),
+            bracket_token: self.bracket_token.clone(),
+            index: self.index.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprLet {
+    fn clone(&self) -> Self {
+        ExprLet {
+            attrs: self.attrs.clone(),
+            let_token: self.let_token.clone(),
+            pat: self.pat.clone(),
+            eq_token: self.eq_token.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for ExprLit {
+    fn clone(&self) -> Self {
+        ExprLit {
+            attrs: self.attrs.clone(),
+            lit: self.lit.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprLoop {
+    fn clone(&self) -> Self {
+        ExprLoop {
+            attrs: self.attrs.clone(),
+            label: self.label.clone(),
+            loop_token: self.loop_token.clone(),
+            body: self.body.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprMacro {
+    fn clone(&self) -> Self {
+        ExprMacro {
+            attrs: self.attrs.clone(),
+            mac: self.mac.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprMatch {
+    fn clone(&self) -> Self {
+        ExprMatch {
+            attrs: self.attrs.clone(),
+            match_token: self.match_token.clone(),
+            expr: self.expr.clone(),
+            brace_token: self.brace_token.clone(),
+            arms: self.arms.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprMethodCall {
+    fn clone(&self) -> Self {
+        ExprMethodCall {
+            attrs: self.attrs.clone(),
+            receiver: self.receiver.clone(),
+            dot_token: self.dot_token.clone(),
+            method: self.method.clone(),
+            turbofish: self.turbofish.clone(),
+            paren_token: self.paren_token.clone(),
+            args: self.args.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for ExprParen {
+    fn clone(&self) -> Self {
+        ExprParen {
+            attrs: self.attrs.clone(),
+            paren_token: self.paren_token.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for ExprPath {
+    fn clone(&self) -> Self {
+        ExprPath {
+            attrs: self.attrs.clone(),
+            qself: self.qself.clone(),
+            path: self.path.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprRange {
+    fn clone(&self) -> Self {
+        ExprRange {
+            attrs: self.attrs.clone(),
+            from: self.from.clone(),
+            limits: self.limits.clone(),
+            to: self.to.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprReference {
+    fn clone(&self) -> Self {
+        ExprReference {
+            attrs: self.attrs.clone(),
+            and_token: self.and_token.clone(),
+            raw: self.raw.clone(),
+            mutability: self.mutability.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprRepeat {
+    fn clone(&self) -> Self {
+        ExprRepeat {
+            attrs: self.attrs.clone(),
+            bracket_token: self.bracket_token.clone(),
+            expr: self.expr.clone(),
+            semi_token: self.semi_token.clone(),
+            len: self.len.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprReturn {
+    fn clone(&self) -> Self {
+        ExprReturn {
+            attrs: self.attrs.clone(),
+            return_token: self.return_token.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprStruct {
+    fn clone(&self) -> Self {
+        ExprStruct {
+            attrs: self.attrs.clone(),
+            path: self.path.clone(),
+            brace_token: self.brace_token.clone(),
+            fields: self.fields.clone(),
+            dot2_token: self.dot2_token.clone(),
+            rest: self.rest.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprTry {
+    fn clone(&self) -> Self {
+        ExprTry {
+            attrs: self.attrs.clone(),
+            expr: self.expr.clone(),
+            question_token: self.question_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprTryBlock {
+    fn clone(&self) -> Self {
+        ExprTryBlock {
+            attrs: self.attrs.clone(),
+            try_token: self.try_token.clone(),
+            block: self.block.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprTuple {
+    fn clone(&self) -> Self {
+        ExprTuple {
+            attrs: self.attrs.clone(),
+            paren_token: self.paren_token.clone(),
+            elems: self.elems.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprType {
+    fn clone(&self) -> Self {
+        ExprType {
+            attrs: self.attrs.clone(),
+            expr: self.expr.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for ExprUnary {
+    fn clone(&self) -> Self {
+        ExprUnary {
+            attrs: self.attrs.clone(),
+            op: self.op.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprUnsafe {
+    fn clone(&self) -> Self {
+        ExprUnsafe {
+            attrs: self.attrs.clone(),
+            unsafe_token: self.unsafe_token.clone(),
+            block: self.block.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprWhile {
+    fn clone(&self) -> Self {
+        ExprWhile {
+            attrs: self.attrs.clone(),
+            label: self.label.clone(),
+            while_token: self.while_token.clone(),
+            cond: self.cond.clone(),
+            body: self.body.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ExprYield {
+    fn clone(&self) -> Self {
+        ExprYield {
+            attrs: self.attrs.clone(),
+            yield_token: self.yield_token.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Field {
+    fn clone(&self) -> Self {
+        Field {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            ident: self.ident.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for FieldPat {
+    fn clone(&self) -> Self {
+        FieldPat {
+            attrs: self.attrs.clone(),
+            member: self.member.clone(),
+            colon_token: self.colon_token.clone(),
+            pat: self.pat.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for FieldValue {
+    fn clone(&self) -> Self {
+        FieldValue {
+            attrs: self.attrs.clone(),
+            member: self.member.clone(),
+            colon_token: self.colon_token.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Fields {
+    fn clone(&self) -> Self {
+        match self {
+            Fields::Named(v0) => Fields::Named(v0.clone()),
+            Fields::Unnamed(v0) => Fields::Unnamed(v0.clone()),
+            Fields::Unit => Fields::Unit,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for FieldsNamed {
+    fn clone(&self) -> Self {
+        FieldsNamed {
+            brace_token: self.brace_token.clone(),
+            named: self.named.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for FieldsUnnamed {
+    fn clone(&self) -> Self {
+        FieldsUnnamed {
+            paren_token: self.paren_token.clone(),
+            unnamed: self.unnamed.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for File {
+    fn clone(&self) -> Self {
+        File {
+            shebang: self.shebang.clone(),
+            attrs: self.attrs.clone(),
+            items: self.items.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for FnArg {
+    fn clone(&self) -> Self {
+        match self {
+            FnArg::Receiver(v0) => FnArg::Receiver(v0.clone()),
+            FnArg::Typed(v0) => FnArg::Typed(v0.clone()),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ForeignItem {
+    fn clone(&self) -> Self {
+        match self {
+            ForeignItem::Fn(v0) => ForeignItem::Fn(v0.clone()),
+            ForeignItem::Static(v0) => ForeignItem::Static(v0.clone()),
+            ForeignItem::Type(v0) => ForeignItem::Type(v0.clone()),
+            ForeignItem::Macro(v0) => ForeignItem::Macro(v0.clone()),
+            ForeignItem::Verbatim(v0) => ForeignItem::Verbatim(v0.clone()),
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ForeignItemFn {
+    fn clone(&self) -> Self {
+        ForeignItemFn {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            sig: self.sig.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ForeignItemMacro {
+    fn clone(&self) -> Self {
+        ForeignItemMacro {
+            attrs: self.attrs.clone(),
+            mac: self.mac.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ForeignItemStatic {
+    fn clone(&self) -> Self {
+        ForeignItemStatic {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            static_token: self.static_token.clone(),
+            mutability: self.mutability.clone(),
+            ident: self.ident.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ForeignItemType {
+    fn clone(&self) -> Self {
+        ForeignItemType {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            type_token: self.type_token.clone(),
+            ident: self.ident.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for GenericArgument {
+    fn clone(&self) -> Self {
+        match self {
+            GenericArgument::Lifetime(v0) => GenericArgument::Lifetime(v0.clone()),
+            GenericArgument::Type(v0) => GenericArgument::Type(v0.clone()),
+            GenericArgument::Binding(v0) => GenericArgument::Binding(v0.clone()),
+            GenericArgument::Constraint(v0) => GenericArgument::Constraint(v0.clone()),
+            GenericArgument::Const(v0) => GenericArgument::Const(v0.clone()),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for GenericMethodArgument {
+    fn clone(&self) -> Self {
+        match self {
+            GenericMethodArgument::Type(v0) => GenericMethodArgument::Type(v0.clone()),
+            GenericMethodArgument::Const(v0) => GenericMethodArgument::Const(v0.clone()),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for GenericParam {
+    fn clone(&self) -> Self {
+        match self {
+            GenericParam::Type(v0) => GenericParam::Type(v0.clone()),
+            GenericParam::Lifetime(v0) => GenericParam::Lifetime(v0.clone()),
+            GenericParam::Const(v0) => GenericParam::Const(v0.clone()),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Generics {
+    fn clone(&self) -> Self {
+        Generics {
+            lt_token: self.lt_token.clone(),
+            params: self.params.clone(),
+            gt_token: self.gt_token.clone(),
+            where_clause: self.where_clause.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ImplItem {
+    fn clone(&self) -> Self {
+        match self {
+            ImplItem::Const(v0) => ImplItem::Const(v0.clone()),
+            ImplItem::Method(v0) => ImplItem::Method(v0.clone()),
+            ImplItem::Type(v0) => ImplItem::Type(v0.clone()),
+            ImplItem::Macro(v0) => ImplItem::Macro(v0.clone()),
+            ImplItem::Verbatim(v0) => ImplItem::Verbatim(v0.clone()),
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ImplItemConst {
+    fn clone(&self) -> Self {
+        ImplItemConst {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            defaultness: self.defaultness.clone(),
+            const_token: self.const_token.clone(),
+            ident: self.ident.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+            eq_token: self.eq_token.clone(),
+            expr: self.expr.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ImplItemMacro {
+    fn clone(&self) -> Self {
+        ImplItemMacro {
+            attrs: self.attrs.clone(),
+            mac: self.mac.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ImplItemMethod {
+    fn clone(&self) -> Self {
+        ImplItemMethod {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            defaultness: self.defaultness.clone(),
+            sig: self.sig.clone(),
+            block: self.block.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ImplItemType {
+    fn clone(&self) -> Self {
+        ImplItemType {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            defaultness: self.defaultness.clone(),
+            type_token: self.type_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            eq_token: self.eq_token.clone(),
+            ty: self.ty.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Index {
+    fn clone(&self) -> Self {
+        Index {
+            index: self.index.clone(),
+            span: self.span.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for Item {
+    fn clone(&self) -> Self {
+        match self {
+            Item::Const(v0) => Item::Const(v0.clone()),
+            Item::Enum(v0) => Item::Enum(v0.clone()),
+            Item::ExternCrate(v0) => Item::ExternCrate(v0.clone()),
+            Item::Fn(v0) => Item::Fn(v0.clone()),
+            Item::ForeignMod(v0) => Item::ForeignMod(v0.clone()),
+            Item::Impl(v0) => Item::Impl(v0.clone()),
+            Item::Macro(v0) => Item::Macro(v0.clone()),
+            Item::Macro2(v0) => Item::Macro2(v0.clone()),
+            Item::Mod(v0) => Item::Mod(v0.clone()),
+            Item::Static(v0) => Item::Static(v0.clone()),
+            Item::Struct(v0) => Item::Struct(v0.clone()),
+            Item::Trait(v0) => Item::Trait(v0.clone()),
+            Item::TraitAlias(v0) => Item::TraitAlias(v0.clone()),
+            Item::Type(v0) => Item::Type(v0.clone()),
+            Item::Union(v0) => Item::Union(v0.clone()),
+            Item::Use(v0) => Item::Use(v0.clone()),
+            Item::Verbatim(v0) => Item::Verbatim(v0.clone()),
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ItemConst {
+    fn clone(&self) -> Self {
+        ItemConst {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            const_token: self.const_token.clone(),
+            ident: self.ident.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+            eq_token: self.eq_token.clone(),
+            expr: self.expr.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ItemEnum {
+    fn clone(&self) -> Self {
+        ItemEnum {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            enum_token: self.enum_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            brace_token: self.brace_token.clone(),
+            variants: self.variants.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ItemExternCrate {
+    fn clone(&self) -> Self {
+        ItemExternCrate {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            extern_token: self.extern_token.clone(),
+            crate_token: self.crate_token.clone(),
+            ident: self.ident.clone(),
+            rename: self.rename.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ItemFn {
+    fn clone(&self) -> Self {
+        ItemFn {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            sig: self.sig.clone(),
+            block: self.block.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ItemForeignMod {
+    fn clone(&self) -> Self {
+        ItemForeignMod {
+            attrs: self.attrs.clone(),
+            abi: self.abi.clone(),
+            brace_token: self.brace_token.clone(),
+            items: self.items.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ItemImpl {
+    fn clone(&self) -> Self {
+        ItemImpl {
+            attrs: self.attrs.clone(),
+            defaultness: self.defaultness.clone(),
+            unsafety: self.unsafety.clone(),
+            impl_token: self.impl_token.clone(),
+            generics: self.generics.clone(),
+            trait_: self.trait_.clone(),
+            self_ty: self.self_ty.clone(),
+            brace_token: self.brace_token.clone(),
+            items: self.items.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ItemMacro {
+    fn clone(&self) -> Self {
+        ItemMacro {
+            attrs: self.attrs.clone(),
+            ident: self.ident.clone(),
+            mac: self.mac.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ItemMacro2 {
+    fn clone(&self) -> Self {
+        ItemMacro2 {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            macro_token: self.macro_token.clone(),
+            ident: self.ident.clone(),
+            rules: self.rules.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ItemMod {
+    fn clone(&self) -> Self {
+        ItemMod {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            mod_token: self.mod_token.clone(),
+            ident: self.ident.clone(),
+            content: self.content.clone(),
+            semi: self.semi.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ItemStatic {
+    fn clone(&self) -> Self {
+        ItemStatic {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            static_token: self.static_token.clone(),
+            mutability: self.mutability.clone(),
+            ident: self.ident.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+            eq_token: self.eq_token.clone(),
+            expr: self.expr.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ItemStruct {
+    fn clone(&self) -> Self {
+        ItemStruct {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            struct_token: self.struct_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            fields: self.fields.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ItemTrait {
+    fn clone(&self) -> Self {
+        ItemTrait {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            unsafety: self.unsafety.clone(),
+            auto_token: self.auto_token.clone(),
+            trait_token: self.trait_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            colon_token: self.colon_token.clone(),
+            supertraits: self.supertraits.clone(),
+            brace_token: self.brace_token.clone(),
+            items: self.items.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ItemTraitAlias {
+    fn clone(&self) -> Self {
+        ItemTraitAlias {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            trait_token: self.trait_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            eq_token: self.eq_token.clone(),
+            bounds: self.bounds.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ItemType {
+    fn clone(&self) -> Self {
+        ItemType {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            type_token: self.type_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            eq_token: self.eq_token.clone(),
+            ty: self.ty.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ItemUnion {
+    fn clone(&self) -> Self {
+        ItemUnion {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            union_token: self.union_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            fields: self.fields.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for ItemUse {
+    fn clone(&self) -> Self {
+        ItemUse {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            use_token: self.use_token.clone(),
+            leading_colon: self.leading_colon.clone(),
+            tree: self.tree.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for Label {
+    fn clone(&self) -> Self {
+        Label {
+            name: self.name.clone(),
+            colon_token: self.colon_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for LifetimeDef {
+    fn clone(&self) -> Self {
+        LifetimeDef {
+            attrs: self.attrs.clone(),
+            lifetime: self.lifetime.clone(),
+            colon_token: self.colon_token.clone(),
+            bounds: self.bounds.clone(),
+        }
+    }
+}
+impl Clone for Lit {
+    fn clone(&self) -> Self {
+        match self {
+            Lit::Str(v0) => Lit::Str(v0.clone()),
+            Lit::ByteStr(v0) => Lit::ByteStr(v0.clone()),
+            Lit::Byte(v0) => Lit::Byte(v0.clone()),
+            Lit::Char(v0) => Lit::Char(v0.clone()),
+            Lit::Int(v0) => Lit::Int(v0.clone()),
+            Lit::Float(v0) => Lit::Float(v0.clone()),
+            Lit::Bool(v0) => Lit::Bool(v0.clone()),
+            Lit::Verbatim(v0) => Lit::Verbatim(v0.clone()),
+        }
+    }
+}
+impl Clone for LitBool {
+    fn clone(&self) -> Self {
+        LitBool {
+            value: self.value.clone(),
+            span: self.span.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for Local {
+    fn clone(&self) -> Self {
+        Local {
+            attrs: self.attrs.clone(),
+            let_token: self.let_token.clone(),
+            pat: self.pat.clone(),
+            init: self.init.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Macro {
+    fn clone(&self) -> Self {
+        Macro {
+            path: self.path.clone(),
+            bang_token: self.bang_token.clone(),
+            delimiter: self.delimiter.clone(),
+            tokens: self.tokens.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for MacroDelimiter {
+    fn clone(&self) -> Self {
+        match self {
+            MacroDelimiter::Paren(v0) => MacroDelimiter::Paren(v0.clone()),
+            MacroDelimiter::Brace(v0) => MacroDelimiter::Brace(v0.clone()),
+            MacroDelimiter::Bracket(v0) => MacroDelimiter::Bracket(v0.clone()),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Member {
+    fn clone(&self) -> Self {
+        match self {
+            Member::Named(v0) => Member::Named(v0.clone()),
+            Member::Unnamed(v0) => Member::Unnamed(v0.clone()),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Meta {
+    fn clone(&self) -> Self {
+        match self {
+            Meta::Path(v0) => Meta::Path(v0.clone()),
+            Meta::List(v0) => Meta::List(v0.clone()),
+            Meta::NameValue(v0) => Meta::NameValue(v0.clone()),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for MetaList {
+    fn clone(&self) -> Self {
+        MetaList {
+            path: self.path.clone(),
+            paren_token: self.paren_token.clone(),
+            nested: self.nested.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for MetaNameValue {
+    fn clone(&self) -> Self {
+        MetaNameValue {
+            path: self.path.clone(),
+            eq_token: self.eq_token.clone(),
+            lit: self.lit.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for MethodTurbofish {
+    fn clone(&self) -> Self {
+        MethodTurbofish {
+            colon2_token: self.colon2_token.clone(),
+            lt_token: self.lt_token.clone(),
+            args: self.args.clone(),
+            gt_token: self.gt_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for NestedMeta {
+    fn clone(&self) -> Self {
+        match self {
+            NestedMeta::Meta(v0) => NestedMeta::Meta(v0.clone()),
+            NestedMeta::Lit(v0) => NestedMeta::Lit(v0.clone()),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for ParenthesizedGenericArguments {
+    fn clone(&self) -> Self {
+        ParenthesizedGenericArguments {
+            paren_token: self.paren_token.clone(),
+            inputs: self.inputs.clone(),
+            output: self.output.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for Pat {
+    fn clone(&self) -> Self {
+        match self {
+            Pat::Box(v0) => Pat::Box(v0.clone()),
+            Pat::Ident(v0) => Pat::Ident(v0.clone()),
+            Pat::Lit(v0) => Pat::Lit(v0.clone()),
+            Pat::Macro(v0) => Pat::Macro(v0.clone()),
+            Pat::Or(v0) => Pat::Or(v0.clone()),
+            Pat::Path(v0) => Pat::Path(v0.clone()),
+            Pat::Range(v0) => Pat::Range(v0.clone()),
+            Pat::Reference(v0) => Pat::Reference(v0.clone()),
+            Pat::Rest(v0) => Pat::Rest(v0.clone()),
+            Pat::Slice(v0) => Pat::Slice(v0.clone()),
+            Pat::Struct(v0) => Pat::Struct(v0.clone()),
+            Pat::Tuple(v0) => Pat::Tuple(v0.clone()),
+            Pat::TupleStruct(v0) => Pat::TupleStruct(v0.clone()),
+            Pat::Type(v0) => Pat::Type(v0.clone()),
+            Pat::Verbatim(v0) => Pat::Verbatim(v0.clone()),
+            Pat::Wild(v0) => Pat::Wild(v0.clone()),
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for PatBox {
+    fn clone(&self) -> Self {
+        PatBox {
+            attrs: self.attrs.clone(),
+            box_token: self.box_token.clone(),
+            pat: self.pat.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for PatIdent {
+    fn clone(&self) -> Self {
+        PatIdent {
+            attrs: self.attrs.clone(),
+            by_ref: self.by_ref.clone(),
+            mutability: self.mutability.clone(),
+            ident: self.ident.clone(),
+            subpat: self.subpat.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for PatLit {
+    fn clone(&self) -> Self {
+        PatLit {
+            attrs: self.attrs.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for PatMacro {
+    fn clone(&self) -> Self {
+        PatMacro {
+            attrs: self.attrs.clone(),
+            mac: self.mac.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for PatOr {
+    fn clone(&self) -> Self {
+        PatOr {
+            attrs: self.attrs.clone(),
+            leading_vert: self.leading_vert.clone(),
+            cases: self.cases.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for PatPath {
+    fn clone(&self) -> Self {
+        PatPath {
+            attrs: self.attrs.clone(),
+            qself: self.qself.clone(),
+            path: self.path.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for PatRange {
+    fn clone(&self) -> Self {
+        PatRange {
+            attrs: self.attrs.clone(),
+            lo: self.lo.clone(),
+            limits: self.limits.clone(),
+            hi: self.hi.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for PatReference {
+    fn clone(&self) -> Self {
+        PatReference {
+            attrs: self.attrs.clone(),
+            and_token: self.and_token.clone(),
+            mutability: self.mutability.clone(),
+            pat: self.pat.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for PatRest {
+    fn clone(&self) -> Self {
+        PatRest {
+            attrs: self.attrs.clone(),
+            dot2_token: self.dot2_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for PatSlice {
+    fn clone(&self) -> Self {
+        PatSlice {
+            attrs: self.attrs.clone(),
+            bracket_token: self.bracket_token.clone(),
+            elems: self.elems.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for PatStruct {
+    fn clone(&self) -> Self {
+        PatStruct {
+            attrs: self.attrs.clone(),
+            path: self.path.clone(),
+            brace_token: self.brace_token.clone(),
+            fields: self.fields.clone(),
+            dot2_token: self.dot2_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for PatTuple {
+    fn clone(&self) -> Self {
+        PatTuple {
+            attrs: self.attrs.clone(),
+            paren_token: self.paren_token.clone(),
+            elems: self.elems.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for PatTupleStruct {
+    fn clone(&self) -> Self {
+        PatTupleStruct {
+            attrs: self.attrs.clone(),
+            path: self.path.clone(),
+            pat: self.pat.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for PatType {
+    fn clone(&self) -> Self {
+        PatType {
+            attrs: self.attrs.clone(),
+            pat: self.pat.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for PatWild {
+    fn clone(&self) -> Self {
+        PatWild {
+            attrs: self.attrs.clone(),
+            underscore_token: self.underscore_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Path {
+    fn clone(&self) -> Self {
+        Path {
+            leading_colon: self.leading_colon.clone(),
+            segments: self.segments.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for PathArguments {
+    fn clone(&self) -> Self {
+        match self {
+            PathArguments::None => PathArguments::None,
+            PathArguments::AngleBracketed(v0) => PathArguments::AngleBracketed(v0.clone()),
+            PathArguments::Parenthesized(v0) => PathArguments::Parenthesized(v0.clone()),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for PathSegment {
+    fn clone(&self) -> Self {
+        PathSegment {
+            ident: self.ident.clone(),
+            arguments: self.arguments.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for PredicateEq {
+    fn clone(&self) -> Self {
+        PredicateEq {
+            lhs_ty: self.lhs_ty.clone(),
+            eq_token: self.eq_token.clone(),
+            rhs_ty: self.rhs_ty.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for PredicateLifetime {
+    fn clone(&self) -> Self {
+        PredicateLifetime {
+            lifetime: self.lifetime.clone(),
+            colon_token: self.colon_token.clone(),
+            bounds: self.bounds.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for PredicateType {
+    fn clone(&self) -> Self {
+        PredicateType {
+            lifetimes: self.lifetimes.clone(),
+            bounded_ty: self.bounded_ty.clone(),
+            colon_token: self.colon_token.clone(),
+            bounds: self.bounds.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for QSelf {
+    fn clone(&self) -> Self {
+        QSelf {
+            lt_token: self.lt_token.clone(),
+            ty: self.ty.clone(),
+            position: self.position.clone(),
+            as_token: self.as_token.clone(),
+            gt_token: self.gt_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Copy for RangeLimits {}
+#[cfg(feature = "full")]
+impl Clone for RangeLimits {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for Receiver {
+    fn clone(&self) -> Self {
+        Receiver {
+            attrs: self.attrs.clone(),
+            reference: self.reference.clone(),
+            mutability: self.mutability.clone(),
+            self_token: self.self_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for ReturnType {
+    fn clone(&self) -> Self {
+        match self {
+            ReturnType::Default => ReturnType::Default,
+            ReturnType::Type(v0, v1) => ReturnType::Type(v0.clone(), v1.clone()),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for Signature {
+    fn clone(&self) -> Self {
+        Signature {
+            constness: self.constness.clone(),
+            asyncness: self.asyncness.clone(),
+            unsafety: self.unsafety.clone(),
+            abi: self.abi.clone(),
+            fn_token: self.fn_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            paren_token: self.paren_token.clone(),
+            inputs: self.inputs.clone(),
+            variadic: self.variadic.clone(),
+            output: self.output.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for Stmt {
+    fn clone(&self) -> Self {
+        match self {
+            Stmt::Local(v0) => Stmt::Local(v0.clone()),
+            Stmt::Item(v0) => Stmt::Item(v0.clone()),
+            Stmt::Expr(v0) => Stmt::Expr(v0.clone()),
+            Stmt::Semi(v0, v1) => Stmt::Semi(v0.clone(), v1.clone()),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TraitBound {
+    fn clone(&self) -> Self {
+        TraitBound {
+            paren_token: self.paren_token.clone(),
+            modifier: self.modifier.clone(),
+            lifetimes: self.lifetimes.clone(),
+            path: self.path.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Copy for TraitBoundModifier {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TraitBoundModifier {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for TraitItem {
+    fn clone(&self) -> Self {
+        match self {
+            TraitItem::Const(v0) => TraitItem::Const(v0.clone()),
+            TraitItem::Method(v0) => TraitItem::Method(v0.clone()),
+            TraitItem::Type(v0) => TraitItem::Type(v0.clone()),
+            TraitItem::Macro(v0) => TraitItem::Macro(v0.clone()),
+            TraitItem::Verbatim(v0) => TraitItem::Verbatim(v0.clone()),
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for TraitItemConst {
+    fn clone(&self) -> Self {
+        TraitItemConst {
+            attrs: self.attrs.clone(),
+            const_token: self.const_token.clone(),
+            ident: self.ident.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+            default: self.default.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for TraitItemMacro {
+    fn clone(&self) -> Self {
+        TraitItemMacro {
+            attrs: self.attrs.clone(),
+            mac: self.mac.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for TraitItemMethod {
+    fn clone(&self) -> Self {
+        TraitItemMethod {
+            attrs: self.attrs.clone(),
+            sig: self.sig.clone(),
+            default: self.default.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for TraitItemType {
+    fn clone(&self) -> Self {
+        TraitItemType {
+            attrs: self.attrs.clone(),
+            type_token: self.type_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            colon_token: self.colon_token.clone(),
+            bounds: self.bounds.clone(),
+            default: self.default.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Type {
+    fn clone(&self) -> Self {
+        match self {
+            Type::Array(v0) => Type::Array(v0.clone()),
+            Type::BareFn(v0) => Type::BareFn(v0.clone()),
+            Type::Group(v0) => Type::Group(v0.clone()),
+            Type::ImplTrait(v0) => Type::ImplTrait(v0.clone()),
+            Type::Infer(v0) => Type::Infer(v0.clone()),
+            Type::Macro(v0) => Type::Macro(v0.clone()),
+            Type::Never(v0) => Type::Never(v0.clone()),
+            Type::Paren(v0) => Type::Paren(v0.clone()),
+            Type::Path(v0) => Type::Path(v0.clone()),
+            Type::Ptr(v0) => Type::Ptr(v0.clone()),
+            Type::Reference(v0) => Type::Reference(v0.clone()),
+            Type::Slice(v0) => Type::Slice(v0.clone()),
+            Type::TraitObject(v0) => Type::TraitObject(v0.clone()),
+            Type::Tuple(v0) => Type::Tuple(v0.clone()),
+            Type::Verbatim(v0) => Type::Verbatim(v0.clone()),
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TypeArray {
+    fn clone(&self) -> Self {
+        TypeArray {
+            bracket_token: self.bracket_token.clone(),
+            elem: self.elem.clone(),
+            semi_token: self.semi_token.clone(),
+            len: self.len.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TypeBareFn {
+    fn clone(&self) -> Self {
+        TypeBareFn {
+            lifetimes: self.lifetimes.clone(),
+            unsafety: self.unsafety.clone(),
+            abi: self.abi.clone(),
+            fn_token: self.fn_token.clone(),
+            paren_token: self.paren_token.clone(),
+            inputs: self.inputs.clone(),
+            variadic: self.variadic.clone(),
+            output: self.output.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TypeGroup {
+    fn clone(&self) -> Self {
+        TypeGroup {
+            group_token: self.group_token.clone(),
+            elem: self.elem.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TypeImplTrait {
+    fn clone(&self) -> Self {
+        TypeImplTrait {
+            impl_token: self.impl_token.clone(),
+            bounds: self.bounds.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TypeInfer {
+    fn clone(&self) -> Self {
+        TypeInfer {
+            underscore_token: self.underscore_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TypeMacro {
+    fn clone(&self) -> Self {
+        TypeMacro {
+            mac: self.mac.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TypeNever {
+    fn clone(&self) -> Self {
+        TypeNever {
+            bang_token: self.bang_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TypeParam {
+    fn clone(&self) -> Self {
+        TypeParam {
+            attrs: self.attrs.clone(),
+            ident: self.ident.clone(),
+            colon_token: self.colon_token.clone(),
+            bounds: self.bounds.clone(),
+            eq_token: self.eq_token.clone(),
+            default: self.default.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TypeParamBound {
+    fn clone(&self) -> Self {
+        match self {
+            TypeParamBound::Trait(v0) => TypeParamBound::Trait(v0.clone()),
+            TypeParamBound::Lifetime(v0) => TypeParamBound::Lifetime(v0.clone()),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TypeParen {
+    fn clone(&self) -> Self {
+        TypeParen {
+            paren_token: self.paren_token.clone(),
+            elem: self.elem.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TypePath {
+    fn clone(&self) -> Self {
+        TypePath {
+            qself: self.qself.clone(),
+            path: self.path.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TypePtr {
+    fn clone(&self) -> Self {
+        TypePtr {
+            star_token: self.star_token.clone(),
+            const_token: self.const_token.clone(),
+            mutability: self.mutability.clone(),
+            elem: self.elem.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TypeReference {
+    fn clone(&self) -> Self {
+        TypeReference {
+            and_token: self.and_token.clone(),
+            lifetime: self.lifetime.clone(),
+            mutability: self.mutability.clone(),
+            elem: self.elem.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TypeSlice {
+    fn clone(&self) -> Self {
+        TypeSlice {
+            bracket_token: self.bracket_token.clone(),
+            elem: self.elem.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TypeTraitObject {
+    fn clone(&self) -> Self {
+        TypeTraitObject {
+            dyn_token: self.dyn_token.clone(),
+            bounds: self.bounds.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for TypeTuple {
+    fn clone(&self) -> Self {
+        TypeTuple {
+            paren_token: self.paren_token.clone(),
+            elems: self.elems.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Copy for UnOp {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for UnOp {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for UseGlob {
+    fn clone(&self) -> Self {
+        UseGlob {
+            star_token: self.star_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for UseGroup {
+    fn clone(&self) -> Self {
+        UseGroup {
+            brace_token: self.brace_token.clone(),
+            items: self.items.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for UseName {
+    fn clone(&self) -> Self {
+        UseName {
+            ident: self.ident.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for UsePath {
+    fn clone(&self) -> Self {
+        UsePath {
+            ident: self.ident.clone(),
+            colon2_token: self.colon2_token.clone(),
+            tree: self.tree.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for UseRename {
+    fn clone(&self) -> Self {
+        UseRename {
+            ident: self.ident.clone(),
+            as_token: self.as_token.clone(),
+            rename: self.rename.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Clone for UseTree {
+    fn clone(&self) -> Self {
+        match self {
+            UseTree::Path(v0) => UseTree::Path(v0.clone()),
+            UseTree::Name(v0) => UseTree::Name(v0.clone()),
+            UseTree::Rename(v0) => UseTree::Rename(v0.clone()),
+            UseTree::Glob(v0) => UseTree::Glob(v0.clone()),
+            UseTree::Group(v0) => UseTree::Group(v0.clone()),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Variadic {
+    fn clone(&self) -> Self {
+        Variadic {
+            attrs: self.attrs.clone(),
+            dots: self.dots.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Variant {
+    fn clone(&self) -> Self {
+        Variant {
+            attrs: self.attrs.clone(),
+            ident: self.ident.clone(),
+            fields: self.fields.clone(),
+            discriminant: self.discriminant.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for VisCrate {
+    fn clone(&self) -> Self {
+        VisCrate {
+            crate_token: self.crate_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for VisPublic {
+    fn clone(&self) -> Self {
+        VisPublic {
+            pub_token: self.pub_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for VisRestricted {
+    fn clone(&self) -> Self {
+        VisRestricted {
+            pub_token: self.pub_token.clone(),
+            paren_token: self.paren_token.clone(),
+            in_token: self.in_token.clone(),
+            path: self.path.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for Visibility {
+    fn clone(&self) -> Self {
+        match self {
+            Visibility::Public(v0) => Visibility::Public(v0.clone()),
+            Visibility::Crate(v0) => Visibility::Crate(v0.clone()),
+            Visibility::Restricted(v0) => Visibility::Restricted(v0.clone()),
+            Visibility::Inherited => Visibility::Inherited,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for WhereClause {
+    fn clone(&self) -> Self {
+        WhereClause {
+            where_token: self.where_token.clone(),
+            predicates: self.predicates.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Clone for WherePredicate {
+    fn clone(&self) -> Self {
+        match self {
+            WherePredicate::Type(v0) => WherePredicate::Type(v0.clone()),
+            WherePredicate::Lifetime(v0) => WherePredicate::Lifetime(v0.clone()),
+            WherePredicate::Eq(v0) => WherePredicate::Eq(v0.clone()),
+        }
+    }
+}
diff --git a/third_party/rust/syn/src/gen/debug.rs b/third_party/rust/syn/src/gen/debug.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/src/gen/debug.rs
@@ -0,0 +1,2857 @@
+// This file is @generated by syn-internal-codegen.
+// It is not intended for manual editing.
+
+use crate::*;
+use std::fmt::{self, Debug};
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Abi {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Abi");
+        formatter.field("extern_token", &self.extern_token);
+        formatter.field("name", &self.name);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for AngleBracketedGenericArguments {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("AngleBracketedGenericArguments");
+        formatter.field("colon2_token", &self.colon2_token);
+        formatter.field("lt_token", &self.lt_token);
+        formatter.field("args", &self.args);
+        formatter.field("gt_token", &self.gt_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for Arm {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Arm");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("pat", &self.pat);
+        formatter.field("guard", &self.guard);
+        formatter.field("fat_arrow_token", &self.fat_arrow_token);
+        formatter.field("body", &self.body);
+        formatter.field("comma", &self.comma);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for AttrStyle {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            AttrStyle::Outer => formatter.write_str("Outer"),
+            AttrStyle::Inner(v0) => {
+                let mut formatter = formatter.debug_tuple("Inner");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Attribute {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Attribute");
+        formatter.field("pound_token", &self.pound_token);
+        formatter.field("style", &self.style);
+        formatter.field("bracket_token", &self.bracket_token);
+        formatter.field("path", &self.path);
+        formatter.field("tokens", &self.tokens);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for BareFnArg {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("BareFnArg");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("name", &self.name);
+        formatter.field("ty", &self.ty);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for BinOp {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            BinOp::Add(v0) => {
+                let mut formatter = formatter.debug_tuple("Add");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::Sub(v0) => {
+                let mut formatter = formatter.debug_tuple("Sub");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::Mul(v0) => {
+                let mut formatter = formatter.debug_tuple("Mul");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::Div(v0) => {
+                let mut formatter = formatter.debug_tuple("Div");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::Rem(v0) => {
+                let mut formatter = formatter.debug_tuple("Rem");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::And(v0) => {
+                let mut formatter = formatter.debug_tuple("And");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::Or(v0) => {
+                let mut formatter = formatter.debug_tuple("Or");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::BitXor(v0) => {
+                let mut formatter = formatter.debug_tuple("BitXor");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::BitAnd(v0) => {
+                let mut formatter = formatter.debug_tuple("BitAnd");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::BitOr(v0) => {
+                let mut formatter = formatter.debug_tuple("BitOr");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::Shl(v0) => {
+                let mut formatter = formatter.debug_tuple("Shl");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::Shr(v0) => {
+                let mut formatter = formatter.debug_tuple("Shr");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::Eq(v0) => {
+                let mut formatter = formatter.debug_tuple("Eq");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::Lt(v0) => {
+                let mut formatter = formatter.debug_tuple("Lt");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::Le(v0) => {
+                let mut formatter = formatter.debug_tuple("Le");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::Ne(v0) => {
+                let mut formatter = formatter.debug_tuple("Ne");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::Ge(v0) => {
+                let mut formatter = formatter.debug_tuple("Ge");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::Gt(v0) => {
+                let mut formatter = formatter.debug_tuple("Gt");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::AddEq(v0) => {
+                let mut formatter = formatter.debug_tuple("AddEq");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::SubEq(v0) => {
+                let mut formatter = formatter.debug_tuple("SubEq");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::MulEq(v0) => {
+                let mut formatter = formatter.debug_tuple("MulEq");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::DivEq(v0) => {
+                let mut formatter = formatter.debug_tuple("DivEq");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::RemEq(v0) => {
+                let mut formatter = formatter.debug_tuple("RemEq");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::BitXorEq(v0) => {
+                let mut formatter = formatter.debug_tuple("BitXorEq");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::BitAndEq(v0) => {
+                let mut formatter = formatter.debug_tuple("BitAndEq");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::BitOrEq(v0) => {
+                let mut formatter = formatter.debug_tuple("BitOrEq");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::ShlEq(v0) => {
+                let mut formatter = formatter.debug_tuple("ShlEq");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            BinOp::ShrEq(v0) => {
+                let mut formatter = formatter.debug_tuple("ShrEq");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Binding {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Binding");
+        formatter.field("ident", &self.ident);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("ty", &self.ty);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for Block {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Block");
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("stmts", &self.stmts);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for BoundLifetimes {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("BoundLifetimes");
+        formatter.field("for_token", &self.for_token);
+        formatter.field("lt_token", &self.lt_token);
+        formatter.field("lifetimes", &self.lifetimes);
+        formatter.field("gt_token", &self.gt_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for ConstParam {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ConstParam");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("const_token", &self.const_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("default", &self.default);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Constraint {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Constraint");
+        formatter.field("ident", &self.ident);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "derive")]
+impl Debug for Data {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Data::Struct(v0) => {
+                let mut formatter = formatter.debug_tuple("Struct");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Data::Enum(v0) => {
+                let mut formatter = formatter.debug_tuple("Enum");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Data::Union(v0) => {
+                let mut formatter = formatter.debug_tuple("Union");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "derive")]
+impl Debug for DataEnum {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("DataEnum");
+        formatter.field("enum_token", &self.enum_token);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("variants", &self.variants);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "derive")]
+impl Debug for DataStruct {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("DataStruct");
+        formatter.field("struct_token", &self.struct_token);
+        formatter.field("fields", &self.fields);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "derive")]
+impl Debug for DataUnion {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("DataUnion");
+        formatter.field("union_token", &self.union_token);
+        formatter.field("fields", &self.fields);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "derive")]
+impl Debug for DeriveInput {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("DeriveInput");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("data", &self.data);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Expr {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            #[cfg(feature = "full")]
+            Expr::Array(v0) => {
+                let mut formatter = formatter.debug_tuple("Array");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Assign(v0) => {
+                let mut formatter = formatter.debug_tuple("Assign");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::AssignOp(v0) => {
+                let mut formatter = formatter.debug_tuple("AssignOp");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Async(v0) => {
+                let mut formatter = formatter.debug_tuple("Async");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Await(v0) => {
+                let mut formatter = formatter.debug_tuple("Await");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Expr::Binary(v0) => {
+                let mut formatter = formatter.debug_tuple("Binary");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Block(v0) => {
+                let mut formatter = formatter.debug_tuple("Block");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Box(v0) => {
+                let mut formatter = formatter.debug_tuple("Box");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Break(v0) => {
+                let mut formatter = formatter.debug_tuple("Break");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Expr::Call(v0) => {
+                let mut formatter = formatter.debug_tuple("Call");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Expr::Cast(v0) => {
+                let mut formatter = formatter.debug_tuple("Cast");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Closure(v0) => {
+                let mut formatter = formatter.debug_tuple("Closure");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Continue(v0) => {
+                let mut formatter = formatter.debug_tuple("Continue");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Expr::Field(v0) => {
+                let mut formatter = formatter.debug_tuple("Field");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::ForLoop(v0) => {
+                let mut formatter = formatter.debug_tuple("ForLoop");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Group(v0) => {
+                let mut formatter = formatter.debug_tuple("Group");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::If(v0) => {
+                let mut formatter = formatter.debug_tuple("If");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Expr::Index(v0) => {
+                let mut formatter = formatter.debug_tuple("Index");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Let(v0) => {
+                let mut formatter = formatter.debug_tuple("Let");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Expr::Lit(v0) => {
+                let mut formatter = formatter.debug_tuple("Lit");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Loop(v0) => {
+                let mut formatter = formatter.debug_tuple("Loop");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Macro(v0) => {
+                let mut formatter = formatter.debug_tuple("Macro");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Match(v0) => {
+                let mut formatter = formatter.debug_tuple("Match");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::MethodCall(v0) => {
+                let mut formatter = formatter.debug_tuple("MethodCall");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Expr::Paren(v0) => {
+                let mut formatter = formatter.debug_tuple("Paren");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Expr::Path(v0) => {
+                let mut formatter = formatter.debug_tuple("Path");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Range(v0) => {
+                let mut formatter = formatter.debug_tuple("Range");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Reference(v0) => {
+                let mut formatter = formatter.debug_tuple("Reference");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Repeat(v0) => {
+                let mut formatter = formatter.debug_tuple("Repeat");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Return(v0) => {
+                let mut formatter = formatter.debug_tuple("Return");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Struct(v0) => {
+                let mut formatter = formatter.debug_tuple("Struct");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Try(v0) => {
+                let mut formatter = formatter.debug_tuple("Try");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::TryBlock(v0) => {
+                let mut formatter = formatter.debug_tuple("TryBlock");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Tuple(v0) => {
+                let mut formatter = formatter.debug_tuple("Tuple");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Type(v0) => {
+                let mut formatter = formatter.debug_tuple("Type");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Expr::Unary(v0) => {
+                let mut formatter = formatter.debug_tuple("Unary");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Unsafe(v0) => {
+                let mut formatter = formatter.debug_tuple("Unsafe");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Expr::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::While(v0) => {
+                let mut formatter = formatter.debug_tuple("While");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            Expr::Yield(v0) => {
+                let mut formatter = formatter.debug_tuple("Yield");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprArray {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprArray");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("bracket_token", &self.bracket_token);
+        formatter.field("elems", &self.elems);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprAssign {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprAssign");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("left", &self.left);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("right", &self.right);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprAssignOp {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprAssignOp");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("left", &self.left);
+        formatter.field("op", &self.op);
+        formatter.field("right", &self.right);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprAsync {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprAsync");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("async_token", &self.async_token);
+        formatter.field("capture", &self.capture);
+        formatter.field("block", &self.block);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprAwait {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprAwait");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("base", &self.base);
+        formatter.field("dot_token", &self.dot_token);
+        formatter.field("await_token", &self.await_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for ExprBinary {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprBinary");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("left", &self.left);
+        formatter.field("op", &self.op);
+        formatter.field("right", &self.right);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprBlock {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprBlock");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("label", &self.label);
+        formatter.field("block", &self.block);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprBox {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprBox");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("box_token", &self.box_token);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprBreak {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprBreak");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("break_token", &self.break_token);
+        formatter.field("label", &self.label);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for ExprCall {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprCall");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("func", &self.func);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("args", &self.args);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for ExprCast {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprCast");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("expr", &self.expr);
+        formatter.field("as_token", &self.as_token);
+        formatter.field("ty", &self.ty);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprClosure {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprClosure");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("asyncness", &self.asyncness);
+        formatter.field("movability", &self.movability);
+        formatter.field("capture", &self.capture);
+        formatter.field("or1_token", &self.or1_token);
+        formatter.field("inputs", &self.inputs);
+        formatter.field("or2_token", &self.or2_token);
+        formatter.field("output", &self.output);
+        formatter.field("body", &self.body);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprContinue {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprContinue");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("continue_token", &self.continue_token);
+        formatter.field("label", &self.label);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for ExprField {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprField");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("base", &self.base);
+        formatter.field("dot_token", &self.dot_token);
+        formatter.field("member", &self.member);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprForLoop {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprForLoop");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("label", &self.label);
+        formatter.field("for_token", &self.for_token);
+        formatter.field("pat", &self.pat);
+        formatter.field("in_token", &self.in_token);
+        formatter.field("expr", &self.expr);
+        formatter.field("body", &self.body);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprGroup {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprGroup");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("group_token", &self.group_token);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprIf {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprIf");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("if_token", &self.if_token);
+        formatter.field("cond", &self.cond);
+        formatter.field("then_branch", &self.then_branch);
+        formatter.field("else_branch", &self.else_branch);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for ExprIndex {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprIndex");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("expr", &self.expr);
+        formatter.field("bracket_token", &self.bracket_token);
+        formatter.field("index", &self.index);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprLet {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprLet");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("let_token", &self.let_token);
+        formatter.field("pat", &self.pat);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for ExprLit {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprLit");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("lit", &self.lit);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprLoop {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprLoop");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("label", &self.label);
+        formatter.field("loop_token", &self.loop_token);
+        formatter.field("body", &self.body);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprMacro {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprMacro");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("mac", &self.mac);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprMatch {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprMatch");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("match_token", &self.match_token);
+        formatter.field("expr", &self.expr);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("arms", &self.arms);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprMethodCall {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprMethodCall");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("receiver", &self.receiver);
+        formatter.field("dot_token", &self.dot_token);
+        formatter.field("method", &self.method);
+        formatter.field("turbofish", &self.turbofish);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("args", &self.args);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for ExprParen {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprParen");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for ExprPath {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprPath");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("qself", &self.qself);
+        formatter.field("path", &self.path);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprRange {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprRange");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("from", &self.from);
+        formatter.field("limits", &self.limits);
+        formatter.field("to", &self.to);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprReference {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprReference");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("and_token", &self.and_token);
+        formatter.field("raw", &self.raw);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprRepeat {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprRepeat");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("bracket_token", &self.bracket_token);
+        formatter.field("expr", &self.expr);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.field("len", &self.len);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprReturn {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprReturn");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("return_token", &self.return_token);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprStruct {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprStruct");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("path", &self.path);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("fields", &self.fields);
+        formatter.field("dot2_token", &self.dot2_token);
+        formatter.field("rest", &self.rest);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprTry {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprTry");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("expr", &self.expr);
+        formatter.field("question_token", &self.question_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprTryBlock {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprTryBlock");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("try_token", &self.try_token);
+        formatter.field("block", &self.block);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprTuple {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprTuple");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("elems", &self.elems);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprType {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprType");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("expr", &self.expr);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for ExprUnary {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprUnary");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("op", &self.op);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprUnsafe {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprUnsafe");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("unsafe_token", &self.unsafe_token);
+        formatter.field("block", &self.block);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprWhile {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprWhile");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("label", &self.label);
+        formatter.field("while_token", &self.while_token);
+        formatter.field("cond", &self.cond);
+        formatter.field("body", &self.body);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ExprYield {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ExprYield");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("yield_token", &self.yield_token);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Field {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Field");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("ident", &self.ident);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for FieldPat {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("FieldPat");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("member", &self.member);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("pat", &self.pat);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for FieldValue {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("FieldValue");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("member", &self.member);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Fields {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Fields::Named(v0) => {
+                let mut formatter = formatter.debug_tuple("Named");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Fields::Unnamed(v0) => {
+                let mut formatter = formatter.debug_tuple("Unnamed");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Fields::Unit => formatter.write_str("Unit"),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for FieldsNamed {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("FieldsNamed");
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("named", &self.named);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for FieldsUnnamed {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("FieldsUnnamed");
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("unnamed", &self.unnamed);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for File {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("File");
+        formatter.field("shebang", &self.shebang);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("items", &self.items);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for FnArg {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            FnArg::Receiver(v0) => {
+                let mut formatter = formatter.debug_tuple("Receiver");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            FnArg::Typed(v0) => {
+                let mut formatter = formatter.debug_tuple("Typed");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ForeignItem {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            ForeignItem::Fn(v0) => {
+                let mut formatter = formatter.debug_tuple("Fn");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            ForeignItem::Static(v0) => {
+                let mut formatter = formatter.debug_tuple("Static");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            ForeignItem::Type(v0) => {
+                let mut formatter = formatter.debug_tuple("Type");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            ForeignItem::Macro(v0) => {
+                let mut formatter = formatter.debug_tuple("Macro");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            ForeignItem::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ForeignItemFn {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ForeignItemFn");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("sig", &self.sig);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ForeignItemMacro {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ForeignItemMacro");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("mac", &self.mac);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ForeignItemStatic {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ForeignItemStatic");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("static_token", &self.static_token);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("ident", &self.ident);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ForeignItemType {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ForeignItemType");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("type_token", &self.type_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for GenericArgument {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            GenericArgument::Lifetime(v0) => {
+                let mut formatter = formatter.debug_tuple("Lifetime");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            GenericArgument::Type(v0) => {
+                let mut formatter = formatter.debug_tuple("Type");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            GenericArgument::Binding(v0) => {
+                let mut formatter = formatter.debug_tuple("Binding");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            GenericArgument::Constraint(v0) => {
+                let mut formatter = formatter.debug_tuple("Constraint");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            GenericArgument::Const(v0) => {
+                let mut formatter = formatter.debug_tuple("Const");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for GenericMethodArgument {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            GenericMethodArgument::Type(v0) => {
+                let mut formatter = formatter.debug_tuple("Type");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            GenericMethodArgument::Const(v0) => {
+                let mut formatter = formatter.debug_tuple("Const");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for GenericParam {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            GenericParam::Type(v0) => {
+                let mut formatter = formatter.debug_tuple("Type");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            GenericParam::Lifetime(v0) => {
+                let mut formatter = formatter.debug_tuple("Lifetime");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            GenericParam::Const(v0) => {
+                let mut formatter = formatter.debug_tuple("Const");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Generics {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Generics");
+        formatter.field("lt_token", &self.lt_token);
+        formatter.field("params", &self.params);
+        formatter.field("gt_token", &self.gt_token);
+        formatter.field("where_clause", &self.where_clause);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ImplItem {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            ImplItem::Const(v0) => {
+                let mut formatter = formatter.debug_tuple("Const");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            ImplItem::Method(v0) => {
+                let mut formatter = formatter.debug_tuple("Method");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            ImplItem::Type(v0) => {
+                let mut formatter = formatter.debug_tuple("Type");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            ImplItem::Macro(v0) => {
+                let mut formatter = formatter.debug_tuple("Macro");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            ImplItem::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ImplItemConst {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ImplItemConst");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("defaultness", &self.defaultness);
+        formatter.field("const_token", &self.const_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("expr", &self.expr);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ImplItemMacro {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ImplItemMacro");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("mac", &self.mac);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ImplItemMethod {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ImplItemMethod");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("defaultness", &self.defaultness);
+        formatter.field("sig", &self.sig);
+        formatter.field("block", &self.block);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ImplItemType {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ImplItemType");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("defaultness", &self.defaultness);
+        formatter.field("type_token", &self.type_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Index {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Index");
+        formatter.field("index", &self.index);
+        formatter.field("span", &self.span);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for Item {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Item::Const(v0) => {
+                let mut formatter = formatter.debug_tuple("Const");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Item::Enum(v0) => {
+                let mut formatter = formatter.debug_tuple("Enum");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Item::ExternCrate(v0) => {
+                let mut formatter = formatter.debug_tuple("ExternCrate");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Item::Fn(v0) => {
+                let mut formatter = formatter.debug_tuple("Fn");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Item::ForeignMod(v0) => {
+                let mut formatter = formatter.debug_tuple("ForeignMod");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Item::Impl(v0) => {
+                let mut formatter = formatter.debug_tuple("Impl");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Item::Macro(v0) => {
+                let mut formatter = formatter.debug_tuple("Macro");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Item::Macro2(v0) => {
+                let mut formatter = formatter.debug_tuple("Macro2");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Item::Mod(v0) => {
+                let mut formatter = formatter.debug_tuple("Mod");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Item::Static(v0) => {
+                let mut formatter = formatter.debug_tuple("Static");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Item::Struct(v0) => {
+                let mut formatter = formatter.debug_tuple("Struct");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Item::Trait(v0) => {
+                let mut formatter = formatter.debug_tuple("Trait");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Item::TraitAlias(v0) => {
+                let mut formatter = formatter.debug_tuple("TraitAlias");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Item::Type(v0) => {
+                let mut formatter = formatter.debug_tuple("Type");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Item::Union(v0) => {
+                let mut formatter = formatter.debug_tuple("Union");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Item::Use(v0) => {
+                let mut formatter = formatter.debug_tuple("Use");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Item::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ItemConst {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ItemConst");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("const_token", &self.const_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("expr", &self.expr);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ItemEnum {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ItemEnum");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("enum_token", &self.enum_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("variants", &self.variants);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ItemExternCrate {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ItemExternCrate");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("extern_token", &self.extern_token);
+        formatter.field("crate_token", &self.crate_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("rename", &self.rename);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ItemFn {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ItemFn");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("sig", &self.sig);
+        formatter.field("block", &self.block);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ItemForeignMod {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ItemForeignMod");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("abi", &self.abi);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("items", &self.items);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ItemImpl {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ItemImpl");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("defaultness", &self.defaultness);
+        formatter.field("unsafety", &self.unsafety);
+        formatter.field("impl_token", &self.impl_token);
+        formatter.field("generics", &self.generics);
+        formatter.field("trait_", &self.trait_);
+        formatter.field("self_ty", &self.self_ty);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("items", &self.items);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ItemMacro {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ItemMacro");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("ident", &self.ident);
+        formatter.field("mac", &self.mac);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ItemMacro2 {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ItemMacro2");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("macro_token", &self.macro_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("rules", &self.rules);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ItemMod {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ItemMod");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("mod_token", &self.mod_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("content", &self.content);
+        formatter.field("semi", &self.semi);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ItemStatic {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ItemStatic");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("static_token", &self.static_token);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("ident", &self.ident);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("expr", &self.expr);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ItemStruct {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ItemStruct");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("struct_token", &self.struct_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("fields", &self.fields);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ItemTrait {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ItemTrait");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("unsafety", &self.unsafety);
+        formatter.field("auto_token", &self.auto_token);
+        formatter.field("trait_token", &self.trait_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("supertraits", &self.supertraits);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("items", &self.items);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ItemTraitAlias {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ItemTraitAlias");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("trait_token", &self.trait_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ItemType {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ItemType");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("type_token", &self.type_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ItemUnion {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ItemUnion");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("union_token", &self.union_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("fields", &self.fields);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for ItemUse {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ItemUse");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("use_token", &self.use_token);
+        formatter.field("leading_colon", &self.leading_colon);
+        formatter.field("tree", &self.tree);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for Label {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Label");
+        formatter.field("name", &self.name);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.finish()
+    }
+}
+impl Debug for Lifetime {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Lifetime");
+        formatter.field("apostrophe", &self.apostrophe);
+        formatter.field("ident", &self.ident);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for LifetimeDef {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("LifetimeDef");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("lifetime", &self.lifetime);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.finish()
+    }
+}
+impl Debug for Lit {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Lit::Str(v0) => {
+                let mut formatter = formatter.debug_tuple("Str");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Lit::ByteStr(v0) => {
+                let mut formatter = formatter.debug_tuple("ByteStr");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Lit::Byte(v0) => {
+                let mut formatter = formatter.debug_tuple("Byte");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Lit::Char(v0) => {
+                let mut formatter = formatter.debug_tuple("Char");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Lit::Int(v0) => {
+                let mut formatter = formatter.debug_tuple("Int");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Lit::Float(v0) => {
+                let mut formatter = formatter.debug_tuple("Float");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Lit::Bool(v0) => {
+                let mut formatter = formatter.debug_tuple("Bool");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Lit::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for Local {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Local");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("let_token", &self.let_token);
+        formatter.field("pat", &self.pat);
+        formatter.field("init", &self.init);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Macro {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Macro");
+        formatter.field("path", &self.path);
+        formatter.field("bang_token", &self.bang_token);
+        formatter.field("delimiter", &self.delimiter);
+        formatter.field("tokens", &self.tokens);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for MacroDelimiter {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            MacroDelimiter::Paren(v0) => {
+                let mut formatter = formatter.debug_tuple("Paren");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            MacroDelimiter::Brace(v0) => {
+                let mut formatter = formatter.debug_tuple("Brace");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            MacroDelimiter::Bracket(v0) => {
+                let mut formatter = formatter.debug_tuple("Bracket");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Member {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Member::Named(v0) => {
+                let mut formatter = formatter.debug_tuple("Named");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Member::Unnamed(v0) => {
+                let mut formatter = formatter.debug_tuple("Unnamed");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Meta {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Meta::Path(v0) => {
+                let mut formatter = formatter.debug_tuple("Path");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Meta::List(v0) => {
+                let mut formatter = formatter.debug_tuple("List");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Meta::NameValue(v0) => {
+                let mut formatter = formatter.debug_tuple("NameValue");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for MetaList {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("MetaList");
+        formatter.field("path", &self.path);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("nested", &self.nested);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for MetaNameValue {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("MetaNameValue");
+        formatter.field("path", &self.path);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("lit", &self.lit);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for MethodTurbofish {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("MethodTurbofish");
+        formatter.field("colon2_token", &self.colon2_token);
+        formatter.field("lt_token", &self.lt_token);
+        formatter.field("args", &self.args);
+        formatter.field("gt_token", &self.gt_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for NestedMeta {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            NestedMeta::Meta(v0) => {
+                let mut formatter = formatter.debug_tuple("Meta");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            NestedMeta::Lit(v0) => {
+                let mut formatter = formatter.debug_tuple("Lit");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for ParenthesizedGenericArguments {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ParenthesizedGenericArguments");
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("inputs", &self.inputs);
+        formatter.field("output", &self.output);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for Pat {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Pat::Box(v0) => {
+                let mut formatter = formatter.debug_tuple("Box");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Pat::Ident(v0) => {
+                let mut formatter = formatter.debug_tuple("Ident");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Pat::Lit(v0) => {
+                let mut formatter = formatter.debug_tuple("Lit");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Pat::Macro(v0) => {
+                let mut formatter = formatter.debug_tuple("Macro");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Pat::Or(v0) => {
+                let mut formatter = formatter.debug_tuple("Or");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Pat::Path(v0) => {
+                let mut formatter = formatter.debug_tuple("Path");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Pat::Range(v0) => {
+                let mut formatter = formatter.debug_tuple("Range");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Pat::Reference(v0) => {
+                let mut formatter = formatter.debug_tuple("Reference");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Pat::Rest(v0) => {
+                let mut formatter = formatter.debug_tuple("Rest");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Pat::Slice(v0) => {
+                let mut formatter = formatter.debug_tuple("Slice");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Pat::Struct(v0) => {
+                let mut formatter = formatter.debug_tuple("Struct");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Pat::Tuple(v0) => {
+                let mut formatter = formatter.debug_tuple("Tuple");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Pat::TupleStruct(v0) => {
+                let mut formatter = formatter.debug_tuple("TupleStruct");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Pat::Type(v0) => {
+                let mut formatter = formatter.debug_tuple("Type");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Pat::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Pat::Wild(v0) => {
+                let mut formatter = formatter.debug_tuple("Wild");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for PatBox {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PatBox");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("box_token", &self.box_token);
+        formatter.field("pat", &self.pat);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for PatIdent {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PatIdent");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("by_ref", &self.by_ref);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("ident", &self.ident);
+        formatter.field("subpat", &self.subpat);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for PatLit {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PatLit");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for PatMacro {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PatMacro");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("mac", &self.mac);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for PatOr {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PatOr");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("leading_vert", &self.leading_vert);
+        formatter.field("cases", &self.cases);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for PatPath {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PatPath");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("qself", &self.qself);
+        formatter.field("path", &self.path);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for PatRange {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PatRange");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("lo", &self.lo);
+        formatter.field("limits", &self.limits);
+        formatter.field("hi", &self.hi);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for PatReference {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PatReference");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("and_token", &self.and_token);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("pat", &self.pat);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for PatRest {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PatRest");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("dot2_token", &self.dot2_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for PatSlice {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PatSlice");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("bracket_token", &self.bracket_token);
+        formatter.field("elems", &self.elems);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for PatStruct {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PatStruct");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("path", &self.path);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("fields", &self.fields);
+        formatter.field("dot2_token", &self.dot2_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for PatTuple {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PatTuple");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("elems", &self.elems);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for PatTupleStruct {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PatTupleStruct");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("path", &self.path);
+        formatter.field("pat", &self.pat);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for PatType {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PatType");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("pat", &self.pat);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for PatWild {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PatWild");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("underscore_token", &self.underscore_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Path {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Path");
+        formatter.field("leading_colon", &self.leading_colon);
+        formatter.field("segments", &self.segments);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for PathArguments {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            PathArguments::None => formatter.write_str("None"),
+            PathArguments::AngleBracketed(v0) => {
+                let mut formatter = formatter.debug_tuple("AngleBracketed");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            PathArguments::Parenthesized(v0) => {
+                let mut formatter = formatter.debug_tuple("Parenthesized");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for PathSegment {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PathSegment");
+        formatter.field("ident", &self.ident);
+        formatter.field("arguments", &self.arguments);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for PredicateEq {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PredicateEq");
+        formatter.field("lhs_ty", &self.lhs_ty);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("rhs_ty", &self.rhs_ty);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for PredicateLifetime {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PredicateLifetime");
+        formatter.field("lifetime", &self.lifetime);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for PredicateType {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PredicateType");
+        formatter.field("lifetimes", &self.lifetimes);
+        formatter.field("bounded_ty", &self.bounded_ty);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for QSelf {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("QSelf");
+        formatter.field("lt_token", &self.lt_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("position", &self.position);
+        formatter.field("as_token", &self.as_token);
+        formatter.field("gt_token", &self.gt_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for RangeLimits {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            RangeLimits::HalfOpen(v0) => {
+                let mut formatter = formatter.debug_tuple("HalfOpen");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            RangeLimits::Closed(v0) => {
+                let mut formatter = formatter.debug_tuple("Closed");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for Receiver {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Receiver");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("reference", &self.reference);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("self_token", &self.self_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for ReturnType {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            ReturnType::Default => formatter.write_str("Default"),
+            ReturnType::Type(v0, v1) => {
+                let mut formatter = formatter.debug_tuple("Type");
+                formatter.field(v0);
+                formatter.field(v1);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for Signature {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Signature");
+        formatter.field("constness", &self.constness);
+        formatter.field("asyncness", &self.asyncness);
+        formatter.field("unsafety", &self.unsafety);
+        formatter.field("abi", &self.abi);
+        formatter.field("fn_token", &self.fn_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("inputs", &self.inputs);
+        formatter.field("variadic", &self.variadic);
+        formatter.field("output", &self.output);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for Stmt {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Stmt::Local(v0) => {
+                let mut formatter = formatter.debug_tuple("Local");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Stmt::Item(v0) => {
+                let mut formatter = formatter.debug_tuple("Item");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Stmt::Expr(v0) => {
+                let mut formatter = formatter.debug_tuple("Expr");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Stmt::Semi(v0, v1) => {
+                let mut formatter = formatter.debug_tuple("Semi");
+                formatter.field(v0);
+                formatter.field(v1);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TraitBound {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TraitBound");
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("modifier", &self.modifier);
+        formatter.field("lifetimes", &self.lifetimes);
+        formatter.field("path", &self.path);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TraitBoundModifier {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            TraitBoundModifier::None => formatter.write_str("None"),
+            TraitBoundModifier::Maybe(v0) => {
+                let mut formatter = formatter.debug_tuple("Maybe");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for TraitItem {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            TraitItem::Const(v0) => {
+                let mut formatter = formatter.debug_tuple("Const");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            TraitItem::Method(v0) => {
+                let mut formatter = formatter.debug_tuple("Method");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            TraitItem::Type(v0) => {
+                let mut formatter = formatter.debug_tuple("Type");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            TraitItem::Macro(v0) => {
+                let mut formatter = formatter.debug_tuple("Macro");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            TraitItem::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for TraitItemConst {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TraitItemConst");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("const_token", &self.const_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("default", &self.default);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for TraitItemMacro {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TraitItemMacro");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("mac", &self.mac);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for TraitItemMethod {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TraitItemMethod");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("sig", &self.sig);
+        formatter.field("default", &self.default);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for TraitItemType {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TraitItemType");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("type_token", &self.type_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.field("default", &self.default);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Type {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Type::Array(v0) => {
+                let mut formatter = formatter.debug_tuple("Array");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Type::BareFn(v0) => {
+                let mut formatter = formatter.debug_tuple("BareFn");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Type::Group(v0) => {
+                let mut formatter = formatter.debug_tuple("Group");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Type::ImplTrait(v0) => {
+                let mut formatter = formatter.debug_tuple("ImplTrait");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Type::Infer(v0) => {
+                let mut formatter = formatter.debug_tuple("Infer");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Type::Macro(v0) => {
+                let mut formatter = formatter.debug_tuple("Macro");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Type::Never(v0) => {
+                let mut formatter = formatter.debug_tuple("Never");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Type::Paren(v0) => {
+                let mut formatter = formatter.debug_tuple("Paren");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Type::Path(v0) => {
+                let mut formatter = formatter.debug_tuple("Path");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Type::Ptr(v0) => {
+                let mut formatter = formatter.debug_tuple("Ptr");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Type::Reference(v0) => {
+                let mut formatter = formatter.debug_tuple("Reference");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Type::Slice(v0) => {
+                let mut formatter = formatter.debug_tuple("Slice");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Type::TraitObject(v0) => {
+                let mut formatter = formatter.debug_tuple("TraitObject");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Type::Tuple(v0) => {
+                let mut formatter = formatter.debug_tuple("Tuple");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Type::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TypeArray {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TypeArray");
+        formatter.field("bracket_token", &self.bracket_token);
+        formatter.field("elem", &self.elem);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.field("len", &self.len);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TypeBareFn {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TypeBareFn");
+        formatter.field("lifetimes", &self.lifetimes);
+        formatter.field("unsafety", &self.unsafety);
+        formatter.field("abi", &self.abi);
+        formatter.field("fn_token", &self.fn_token);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("inputs", &self.inputs);
+        formatter.field("variadic", &self.variadic);
+        formatter.field("output", &self.output);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TypeGroup {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TypeGroup");
+        formatter.field("group_token", &self.group_token);
+        formatter.field("elem", &self.elem);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TypeImplTrait {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TypeImplTrait");
+        formatter.field("impl_token", &self.impl_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TypeInfer {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TypeInfer");
+        formatter.field("underscore_token", &self.underscore_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TypeMacro {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TypeMacro");
+        formatter.field("mac", &self.mac);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TypeNever {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TypeNever");
+        formatter.field("bang_token", &self.bang_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TypeParam {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TypeParam");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("ident", &self.ident);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("default", &self.default);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TypeParamBound {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            TypeParamBound::Trait(v0) => {
+                let mut formatter = formatter.debug_tuple("Trait");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            TypeParamBound::Lifetime(v0) => {
+                let mut formatter = formatter.debug_tuple("Lifetime");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TypeParen {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TypeParen");
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("elem", &self.elem);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TypePath {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TypePath");
+        formatter.field("qself", &self.qself);
+        formatter.field("path", &self.path);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TypePtr {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TypePtr");
+        formatter.field("star_token", &self.star_token);
+        formatter.field("const_token", &self.const_token);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("elem", &self.elem);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TypeReference {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TypeReference");
+        formatter.field("and_token", &self.and_token);
+        formatter.field("lifetime", &self.lifetime);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("elem", &self.elem);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TypeSlice {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TypeSlice");
+        formatter.field("bracket_token", &self.bracket_token);
+        formatter.field("elem", &self.elem);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TypeTraitObject {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TypeTraitObject");
+        formatter.field("dyn_token", &self.dyn_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for TypeTuple {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TypeTuple");
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("elems", &self.elems);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for UnOp {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            UnOp::Deref(v0) => {
+                let mut formatter = formatter.debug_tuple("Deref");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            UnOp::Not(v0) => {
+                let mut formatter = formatter.debug_tuple("Not");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            UnOp::Neg(v0) => {
+                let mut formatter = formatter.debug_tuple("Neg");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for UseGlob {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("UseGlob");
+        formatter.field("star_token", &self.star_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for UseGroup {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("UseGroup");
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("items", &self.items);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for UseName {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("UseName");
+        formatter.field("ident", &self.ident);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for UsePath {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("UsePath");
+        formatter.field("ident", &self.ident);
+        formatter.field("colon2_token", &self.colon2_token);
+        formatter.field("tree", &self.tree);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for UseRename {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("UseRename");
+        formatter.field("ident", &self.ident);
+        formatter.field("as_token", &self.as_token);
+        formatter.field("rename", &self.rename);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+impl Debug for UseTree {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            UseTree::Path(v0) => {
+                let mut formatter = formatter.debug_tuple("Path");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            UseTree::Name(v0) => {
+                let mut formatter = formatter.debug_tuple("Name");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            UseTree::Rename(v0) => {
+                let mut formatter = formatter.debug_tuple("Rename");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            UseTree::Glob(v0) => {
+                let mut formatter = formatter.debug_tuple("Glob");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            UseTree::Group(v0) => {
+                let mut formatter = formatter.debug_tuple("Group");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Variadic {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Variadic");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("dots", &self.dots);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Variant {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Variant");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("ident", &self.ident);
+        formatter.field("fields", &self.fields);
+        formatter.field("discriminant", &self.discriminant);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for VisCrate {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("VisCrate");
+        formatter.field("crate_token", &self.crate_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for VisPublic {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("VisPublic");
+        formatter.field("pub_token", &self.pub_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for VisRestricted {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("VisRestricted");
+        formatter.field("pub_token", &self.pub_token);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("in_token", &self.in_token);
+        formatter.field("path", &self.path);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for Visibility {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Visibility::Public(v0) => {
+                let mut formatter = formatter.debug_tuple("Public");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Visibility::Crate(v0) => {
+                let mut formatter = formatter.debug_tuple("Crate");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Visibility::Restricted(v0) => {
+                let mut formatter = formatter.debug_tuple("Restricted");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            Visibility::Inherited => formatter.write_str("Inherited"),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for WhereClause {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("WhereClause");
+        formatter.field("where_token", &self.where_token);
+        formatter.field("predicates", &self.predicates);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Debug for WherePredicate {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            WherePredicate::Type(v0) => {
+                let mut formatter = formatter.debug_tuple("Type");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            WherePredicate::Lifetime(v0) => {
+                let mut formatter = formatter.debug_tuple("Lifetime");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            WherePredicate::Eq(v0) => {
+                let mut formatter = formatter.debug_tuple("Eq");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
diff --git a/third_party/rust/syn/src/gen/eq.rs b/third_party/rust/syn/src/gen/eq.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/src/gen/eq.rs
@@ -0,0 +1,1930 @@
+// This file is @generated by syn-internal-codegen.
+// It is not intended for manual editing.
+
+#[cfg(any(feature = "derive", feature = "full"))]
+use crate::tt::TokenStreamHelper;
+use crate::*;
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for Abi {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for Abi {
+    fn eq(&self, other: &Self) -> bool {
+        self.name == other.name
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for AngleBracketedGenericArguments {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for AngleBracketedGenericArguments {
+    fn eq(&self, other: &Self) -> bool {
+        self.colon2_token == other.colon2_token && self.args == other.args
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for Arm {}
+#[cfg(feature = "full")]
+impl PartialEq for Arm {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.pat == other.pat
+            && self.guard == other.guard
+            && self.body == other.body
+            && self.comma == other.comma
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for AttrStyle {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for AttrStyle {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (AttrStyle::Outer, AttrStyle::Outer) => true,
+            (AttrStyle::Inner(_), AttrStyle::Inner(_)) => true,
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for Attribute {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for Attribute {
+    fn eq(&self, other: &Self) -> bool {
+        self.style == other.style
+            && self.path == other.path
+            && TokenStreamHelper(&self.tokens) == TokenStreamHelper(&other.tokens)
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for BareFnArg {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for BareFnArg {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.name == other.name && self.ty == other.ty
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for BinOp {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for BinOp {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (BinOp::Add(_), BinOp::Add(_)) => true,
+            (BinOp::Sub(_), BinOp::Sub(_)) => true,
+            (BinOp::Mul(_), BinOp::Mul(_)) => true,
+            (BinOp::Div(_), BinOp::Div(_)) => true,
+            (BinOp::Rem(_), BinOp::Rem(_)) => true,
+            (BinOp::And(_), BinOp::And(_)) => true,
+            (BinOp::Or(_), BinOp::Or(_)) => true,
+            (BinOp::BitXor(_), BinOp::BitXor(_)) => true,
+            (BinOp::BitAnd(_), BinOp::BitAnd(_)) => true,
+            (BinOp::BitOr(_), BinOp::BitOr(_)) => true,
+            (BinOp::Shl(_), BinOp::Shl(_)) => true,
+            (BinOp::Shr(_), BinOp::Shr(_)) => true,
+            (BinOp::Eq(_), BinOp::Eq(_)) => true,
+            (BinOp::Lt(_), BinOp::Lt(_)) => true,
+            (BinOp::Le(_), BinOp::Le(_)) => true,
+            (BinOp::Ne(_), BinOp::Ne(_)) => true,
+            (BinOp::Ge(_), BinOp::Ge(_)) => true,
+            (BinOp::Gt(_), BinOp::Gt(_)) => true,
+            (BinOp::AddEq(_), BinOp::AddEq(_)) => true,
+            (BinOp::SubEq(_), BinOp::SubEq(_)) => true,
+            (BinOp::MulEq(_), BinOp::MulEq(_)) => true,
+            (BinOp::DivEq(_), BinOp::DivEq(_)) => true,
+            (BinOp::RemEq(_), BinOp::RemEq(_)) => true,
+            (BinOp::BitXorEq(_), BinOp::BitXorEq(_)) => true,
+            (BinOp::BitAndEq(_), BinOp::BitAndEq(_)) => true,
+            (BinOp::BitOrEq(_), BinOp::BitOrEq(_)) => true,
+            (BinOp::ShlEq(_), BinOp::ShlEq(_)) => true,
+            (BinOp::ShrEq(_), BinOp::ShrEq(_)) => true,
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for Binding {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for Binding {
+    fn eq(&self, other: &Self) -> bool {
+        self.ident == other.ident && self.ty == other.ty
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for Block {}
+#[cfg(feature = "full")]
+impl PartialEq for Block {
+    fn eq(&self, other: &Self) -> bool {
+        self.stmts == other.stmts
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for BoundLifetimes {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for BoundLifetimes {
+    fn eq(&self, other: &Self) -> bool {
+        self.lifetimes == other.lifetimes
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for ConstParam {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for ConstParam {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.ident == other.ident
+            && self.ty == other.ty
+            && self.eq_token == other.eq_token
+            && self.default == other.default
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for Constraint {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for Constraint {
+    fn eq(&self, other: &Self) -> bool {
+        self.ident == other.ident && self.bounds == other.bounds
+    }
+}
+#[cfg(feature = "derive")]
+impl Eq for Data {}
+#[cfg(feature = "derive")]
+impl PartialEq for Data {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (Data::Struct(self0), Data::Struct(other0)) => self0 == other0,
+            (Data::Enum(self0), Data::Enum(other0)) => self0 == other0,
+            (Data::Union(self0), Data::Union(other0)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "derive")]
+impl Eq for DataEnum {}
+#[cfg(feature = "derive")]
+impl PartialEq for DataEnum {
+    fn eq(&self, other: &Self) -> bool {
+        self.variants == other.variants
+    }
+}
+#[cfg(feature = "derive")]
+impl Eq for DataStruct {}
+#[cfg(feature = "derive")]
+impl PartialEq for DataStruct {
+    fn eq(&self, other: &Self) -> bool {
+        self.fields == other.fields && self.semi_token == other.semi_token
+    }
+}
+#[cfg(feature = "derive")]
+impl Eq for DataUnion {}
+#[cfg(feature = "derive")]
+impl PartialEq for DataUnion {
+    fn eq(&self, other: &Self) -> bool {
+        self.fields == other.fields
+    }
+}
+#[cfg(feature = "derive")]
+impl Eq for DeriveInput {}
+#[cfg(feature = "derive")]
+impl PartialEq for DeriveInput {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.ident == other.ident
+            && self.generics == other.generics
+            && self.data == other.data
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for Expr {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for Expr {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            #[cfg(feature = "full")]
+            (Expr::Array(self0), Expr::Array(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Assign(self0), Expr::Assign(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::AssignOp(self0), Expr::AssignOp(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Async(self0), Expr::Async(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Await(self0), Expr::Await(other0)) => self0 == other0,
+            (Expr::Binary(self0), Expr::Binary(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Block(self0), Expr::Block(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Box(self0), Expr::Box(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Break(self0), Expr::Break(other0)) => self0 == other0,
+            (Expr::Call(self0), Expr::Call(other0)) => self0 == other0,
+            (Expr::Cast(self0), Expr::Cast(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Closure(self0), Expr::Closure(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Continue(self0), Expr::Continue(other0)) => self0 == other0,
+            (Expr::Field(self0), Expr::Field(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::ForLoop(self0), Expr::ForLoop(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Group(self0), Expr::Group(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::If(self0), Expr::If(other0)) => self0 == other0,
+            (Expr::Index(self0), Expr::Index(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Let(self0), Expr::Let(other0)) => self0 == other0,
+            (Expr::Lit(self0), Expr::Lit(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Loop(self0), Expr::Loop(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Macro(self0), Expr::Macro(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Match(self0), Expr::Match(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::MethodCall(self0), Expr::MethodCall(other0)) => self0 == other0,
+            (Expr::Paren(self0), Expr::Paren(other0)) => self0 == other0,
+            (Expr::Path(self0), Expr::Path(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Range(self0), Expr::Range(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Reference(self0), Expr::Reference(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Repeat(self0), Expr::Repeat(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Return(self0), Expr::Return(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Struct(self0), Expr::Struct(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Try(self0), Expr::Try(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::TryBlock(self0), Expr::TryBlock(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Tuple(self0), Expr::Tuple(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Type(self0), Expr::Type(other0)) => self0 == other0,
+            (Expr::Unary(self0), Expr::Unary(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Unsafe(self0), Expr::Unsafe(other0)) => self0 == other0,
+            (Expr::Verbatim(self0), Expr::Verbatim(other0)) => {
+                TokenStreamHelper(self0) == TokenStreamHelper(other0)
+            }
+            #[cfg(feature = "full")]
+            (Expr::While(self0), Expr::While(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (Expr::Yield(self0), Expr::Yield(other0)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprArray {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprArray {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.elems == other.elems
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprAssign {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprAssign {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.left == other.left && self.right == other.right
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprAssignOp {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprAssignOp {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.left == other.left
+            && self.op == other.op
+            && self.right == other.right
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprAsync {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprAsync {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.capture == other.capture && self.block == other.block
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprAwait {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprAwait {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.base == other.base
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for ExprBinary {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for ExprBinary {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.left == other.left
+            && self.op == other.op
+            && self.right == other.right
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprBlock {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprBlock {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.label == other.label && self.block == other.block
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprBox {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprBox {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprBreak {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprBreak {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.label == other.label && self.expr == other.expr
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for ExprCall {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for ExprCall {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.func == other.func && self.args == other.args
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for ExprCast {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for ExprCast {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr && self.ty == other.ty
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprClosure {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprClosure {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.asyncness == other.asyncness
+            && self.movability == other.movability
+            && self.capture == other.capture
+            && self.inputs == other.inputs
+            && self.output == other.output
+            && self.body == other.body
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprContinue {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprContinue {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.label == other.label
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for ExprField {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for ExprField {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.base == other.base && self.member == other.member
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprForLoop {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprForLoop {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.label == other.label
+            && self.pat == other.pat
+            && self.expr == other.expr
+            && self.body == other.body
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprGroup {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprGroup {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprIf {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprIf {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.cond == other.cond
+            && self.then_branch == other.then_branch
+            && self.else_branch == other.else_branch
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for ExprIndex {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for ExprIndex {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr && self.index == other.index
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprLet {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprLet {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.pat == other.pat && self.expr == other.expr
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for ExprLit {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for ExprLit {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.lit == other.lit
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprLoop {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprLoop {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.label == other.label && self.body == other.body
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprMacro {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprMacro {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.mac == other.mac
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprMatch {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprMatch {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr && self.arms == other.arms
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprMethodCall {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprMethodCall {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.receiver == other.receiver
+            && self.method == other.method
+            && self.turbofish == other.turbofish
+            && self.args == other.args
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for ExprParen {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for ExprParen {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for ExprPath {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for ExprPath {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.qself == other.qself && self.path == other.path
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprRange {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprRange {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.from == other.from
+            && self.limits == other.limits
+            && self.to == other.to
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprReference {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprReference {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.mutability == other.mutability && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprRepeat {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprRepeat {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr && self.len == other.len
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprReturn {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprReturn {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprStruct {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprStruct {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.path == other.path
+            && self.fields == other.fields
+            && self.dot2_token == other.dot2_token
+            && self.rest == other.rest
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprTry {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprTry {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprTryBlock {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprTryBlock {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.block == other.block
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprTuple {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprTuple {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.elems == other.elems
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprType {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprType {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr && self.ty == other.ty
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for ExprUnary {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for ExprUnary {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.op == other.op && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprUnsafe {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprUnsafe {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.block == other.block
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprWhile {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprWhile {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.label == other.label
+            && self.cond == other.cond
+            && self.body == other.body
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ExprYield {}
+#[cfg(feature = "full")]
+impl PartialEq for ExprYield {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for Field {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for Field {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.ident == other.ident
+            && self.colon_token == other.colon_token
+            && self.ty == other.ty
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for FieldPat {}
+#[cfg(feature = "full")]
+impl PartialEq for FieldPat {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.member == other.member
+            && self.colon_token == other.colon_token
+            && self.pat == other.pat
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for FieldValue {}
+#[cfg(feature = "full")]
+impl PartialEq for FieldValue {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.member == other.member
+            && self.colon_token == other.colon_token
+            && self.expr == other.expr
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for Fields {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for Fields {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (Fields::Named(self0), Fields::Named(other0)) => self0 == other0,
+            (Fields::Unnamed(self0), Fields::Unnamed(other0)) => self0 == other0,
+            (Fields::Unit, Fields::Unit) => true,
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for FieldsNamed {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for FieldsNamed {
+    fn eq(&self, other: &Self) -> bool {
+        self.named == other.named
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for FieldsUnnamed {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for FieldsUnnamed {
+    fn eq(&self, other: &Self) -> bool {
+        self.unnamed == other.unnamed
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for File {}
+#[cfg(feature = "full")]
+impl PartialEq for File {
+    fn eq(&self, other: &Self) -> bool {
+        self.shebang == other.shebang && self.attrs == other.attrs && self.items == other.items
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for FnArg {}
+#[cfg(feature = "full")]
+impl PartialEq for FnArg {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (FnArg::Receiver(self0), FnArg::Receiver(other0)) => self0 == other0,
+            (FnArg::Typed(self0), FnArg::Typed(other0)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ForeignItem {}
+#[cfg(feature = "full")]
+impl PartialEq for ForeignItem {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (ForeignItem::Fn(self0), ForeignItem::Fn(other0)) => self0 == other0,
+            (ForeignItem::Static(self0), ForeignItem::Static(other0)) => self0 == other0,
+            (ForeignItem::Type(self0), ForeignItem::Type(other0)) => self0 == other0,
+            (ForeignItem::Macro(self0), ForeignItem::Macro(other0)) => self0 == other0,
+            (ForeignItem::Verbatim(self0), ForeignItem::Verbatim(other0)) => {
+                TokenStreamHelper(self0) == TokenStreamHelper(other0)
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ForeignItemFn {}
+#[cfg(feature = "full")]
+impl PartialEq for ForeignItemFn {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis && self.sig == other.sig
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ForeignItemMacro {}
+#[cfg(feature = "full")]
+impl PartialEq for ForeignItemMacro {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.mac == other.mac && self.semi_token == other.semi_token
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ForeignItemStatic {}
+#[cfg(feature = "full")]
+impl PartialEq for ForeignItemStatic {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.mutability == other.mutability
+            && self.ident == other.ident
+            && self.ty == other.ty
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ForeignItemType {}
+#[cfg(feature = "full")]
+impl PartialEq for ForeignItemType {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis && self.ident == other.ident
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for GenericArgument {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for GenericArgument {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (GenericArgument::Lifetime(self0), GenericArgument::Lifetime(other0)) => {
+                self0 == other0
+            }
+            (GenericArgument::Type(self0), GenericArgument::Type(other0)) => self0 == other0,
+            (GenericArgument::Binding(self0), GenericArgument::Binding(other0)) => self0 == other0,
+            (GenericArgument::Constraint(self0), GenericArgument::Constraint(other0)) => {
+                self0 == other0
+            }
+            (GenericArgument::Const(self0), GenericArgument::Const(other0)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for GenericMethodArgument {}
+#[cfg(feature = "full")]
+impl PartialEq for GenericMethodArgument {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (GenericMethodArgument::Type(self0), GenericMethodArgument::Type(other0)) => {
+                self0 == other0
+            }
+            (GenericMethodArgument::Const(self0), GenericMethodArgument::Const(other0)) => {
+                self0 == other0
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for GenericParam {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for GenericParam {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (GenericParam::Type(self0), GenericParam::Type(other0)) => self0 == other0,
+            (GenericParam::Lifetime(self0), GenericParam::Lifetime(other0)) => self0 == other0,
+            (GenericParam::Const(self0), GenericParam::Const(other0)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for Generics {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for Generics {
+    fn eq(&self, other: &Self) -> bool {
+        self.lt_token == other.lt_token
+            && self.params == other.params
+            && self.gt_token == other.gt_token
+            && self.where_clause == other.where_clause
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ImplItem {}
+#[cfg(feature = "full")]
+impl PartialEq for ImplItem {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (ImplItem::Const(self0), ImplItem::Const(other0)) => self0 == other0,
+            (ImplItem::Method(self0), ImplItem::Method(other0)) => self0 == other0,
+            (ImplItem::Type(self0), ImplItem::Type(other0)) => self0 == other0,
+            (ImplItem::Macro(self0), ImplItem::Macro(other0)) => self0 == other0,
+            (ImplItem::Verbatim(self0), ImplItem::Verbatim(other0)) => {
+                TokenStreamHelper(self0) == TokenStreamHelper(other0)
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ImplItemConst {}
+#[cfg(feature = "full")]
+impl PartialEq for ImplItemConst {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.defaultness == other.defaultness
+            && self.ident == other.ident
+            && self.ty == other.ty
+            && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ImplItemMacro {}
+#[cfg(feature = "full")]
+impl PartialEq for ImplItemMacro {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.mac == other.mac && self.semi_token == other.semi_token
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ImplItemMethod {}
+#[cfg(feature = "full")]
+impl PartialEq for ImplItemMethod {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.defaultness == other.defaultness
+            && self.sig == other.sig
+            && self.block == other.block
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ImplItemType {}
+#[cfg(feature = "full")]
+impl PartialEq for ImplItemType {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.defaultness == other.defaultness
+            && self.ident == other.ident
+            && self.generics == other.generics
+            && self.ty == other.ty
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for Item {}
+#[cfg(feature = "full")]
+impl PartialEq for Item {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (Item::Const(self0), Item::Const(other0)) => self0 == other0,
+            (Item::Enum(self0), Item::Enum(other0)) => self0 == other0,
+            (Item::ExternCrate(self0), Item::ExternCrate(other0)) => self0 == other0,
+            (Item::Fn(self0), Item::Fn(other0)) => self0 == other0,
+            (Item::ForeignMod(self0), Item::ForeignMod(other0)) => self0 == other0,
+            (Item::Impl(self0), Item::Impl(other0)) => self0 == other0,
+            (Item::Macro(self0), Item::Macro(other0)) => self0 == other0,
+            (Item::Macro2(self0), Item::Macro2(other0)) => self0 == other0,
+            (Item::Mod(self0), Item::Mod(other0)) => self0 == other0,
+            (Item::Static(self0), Item::Static(other0)) => self0 == other0,
+            (Item::Struct(self0), Item::Struct(other0)) => self0 == other0,
+            (Item::Trait(self0), Item::Trait(other0)) => self0 == other0,
+            (Item::TraitAlias(self0), Item::TraitAlias(other0)) => self0 == other0,
+            (Item::Type(self0), Item::Type(other0)) => self0 == other0,
+            (Item::Union(self0), Item::Union(other0)) => self0 == other0,
+            (Item::Use(self0), Item::Use(other0)) => self0 == other0,
+            (Item::Verbatim(self0), Item::Verbatim(other0)) => {
+                TokenStreamHelper(self0) == TokenStreamHelper(other0)
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ItemConst {}
+#[cfg(feature = "full")]
+impl PartialEq for ItemConst {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.ident == other.ident
+            && self.ty == other.ty
+            && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ItemEnum {}
+#[cfg(feature = "full")]
+impl PartialEq for ItemEnum {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.ident == other.ident
+            && self.generics == other.generics
+            && self.variants == other.variants
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ItemExternCrate {}
+#[cfg(feature = "full")]
+impl PartialEq for ItemExternCrate {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.ident == other.ident
+            && self.rename == other.rename
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ItemFn {}
+#[cfg(feature = "full")]
+impl PartialEq for ItemFn {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.sig == other.sig
+            && self.block == other.block
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ItemForeignMod {}
+#[cfg(feature = "full")]
+impl PartialEq for ItemForeignMod {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.abi == other.abi && self.items == other.items
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ItemImpl {}
+#[cfg(feature = "full")]
+impl PartialEq for ItemImpl {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.defaultness == other.defaultness
+            && self.unsafety == other.unsafety
+            && self.generics == other.generics
+            && self.trait_ == other.trait_
+            && self.self_ty == other.self_ty
+            && self.items == other.items
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ItemMacro {}
+#[cfg(feature = "full")]
+impl PartialEq for ItemMacro {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.ident == other.ident
+            && self.mac == other.mac
+            && self.semi_token == other.semi_token
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ItemMacro2 {}
+#[cfg(feature = "full")]
+impl PartialEq for ItemMacro2 {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.ident == other.ident
+            && TokenStreamHelper(&self.rules) == TokenStreamHelper(&other.rules)
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ItemMod {}
+#[cfg(feature = "full")]
+impl PartialEq for ItemMod {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.ident == other.ident
+            && self.content == other.content
+            && self.semi == other.semi
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ItemStatic {}
+#[cfg(feature = "full")]
+impl PartialEq for ItemStatic {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.mutability == other.mutability
+            && self.ident == other.ident
+            && self.ty == other.ty
+            && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ItemStruct {}
+#[cfg(feature = "full")]
+impl PartialEq for ItemStruct {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.ident == other.ident
+            && self.generics == other.generics
+            && self.fields == other.fields
+            && self.semi_token == other.semi_token
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ItemTrait {}
+#[cfg(feature = "full")]
+impl PartialEq for ItemTrait {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.unsafety == other.unsafety
+            && self.auto_token == other.auto_token
+            && self.ident == other.ident
+            && self.generics == other.generics
+            && self.colon_token == other.colon_token
+            && self.supertraits == other.supertraits
+            && self.items == other.items
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ItemTraitAlias {}
+#[cfg(feature = "full")]
+impl PartialEq for ItemTraitAlias {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.ident == other.ident
+            && self.generics == other.generics
+            && self.bounds == other.bounds
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ItemType {}
+#[cfg(feature = "full")]
+impl PartialEq for ItemType {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.ident == other.ident
+            && self.generics == other.generics
+            && self.ty == other.ty
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ItemUnion {}
+#[cfg(feature = "full")]
+impl PartialEq for ItemUnion {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.ident == other.ident
+            && self.generics == other.generics
+            && self.fields == other.fields
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for ItemUse {}
+#[cfg(feature = "full")]
+impl PartialEq for ItemUse {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.vis == other.vis
+            && self.leading_colon == other.leading_colon
+            && self.tree == other.tree
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for Label {}
+#[cfg(feature = "full")]
+impl PartialEq for Label {
+    fn eq(&self, other: &Self) -> bool {
+        self.name == other.name
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for LifetimeDef {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for LifetimeDef {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.lifetime == other.lifetime
+            && self.colon_token == other.colon_token
+            && self.bounds == other.bounds
+    }
+}
+impl Eq for Lit {}
+impl PartialEq for Lit {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (Lit::Str(self0), Lit::Str(other0)) => self0 == other0,
+            (Lit::ByteStr(self0), Lit::ByteStr(other0)) => self0 == other0,
+            (Lit::Byte(self0), Lit::Byte(other0)) => self0 == other0,
+            (Lit::Char(self0), Lit::Char(other0)) => self0 == other0,
+            (Lit::Int(self0), Lit::Int(other0)) => self0 == other0,
+            (Lit::Float(self0), Lit::Float(other0)) => self0 == other0,
+            (Lit::Bool(self0), Lit::Bool(other0)) => self0 == other0,
+            (Lit::Verbatim(self0), Lit::Verbatim(other0)) => {
+                self0.to_string() == other0.to_string()
+            }
+            _ => false,
+        }
+    }
+}
+impl Eq for LitBool {}
+impl PartialEq for LitBool {
+    fn eq(&self, other: &Self) -> bool {
+        self.value == other.value
+    }
+}
+impl Eq for LitByte {}
+impl Eq for LitByteStr {}
+impl Eq for LitChar {}
+impl Eq for LitFloat {}
+impl Eq for LitInt {}
+impl Eq for LitStr {}
+#[cfg(feature = "full")]
+impl Eq for Local {}
+#[cfg(feature = "full")]
+impl PartialEq for Local {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.pat == other.pat && self.init == other.init
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for Macro {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for Macro {
+    fn eq(&self, other: &Self) -> bool {
+        self.path == other.path
+            && self.delimiter == other.delimiter
+            && TokenStreamHelper(&self.tokens) == TokenStreamHelper(&other.tokens)
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for MacroDelimiter {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for MacroDelimiter {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (MacroDelimiter::Paren(_), MacroDelimiter::Paren(_)) => true,
+            (MacroDelimiter::Brace(_), MacroDelimiter::Brace(_)) => true,
+            (MacroDelimiter::Bracket(_), MacroDelimiter::Bracket(_)) => true,
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for Meta {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for Meta {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (Meta::Path(self0), Meta::Path(other0)) => self0 == other0,
+            (Meta::List(self0), Meta::List(other0)) => self0 == other0,
+            (Meta::NameValue(self0), Meta::NameValue(other0)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for MetaList {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for MetaList {
+    fn eq(&self, other: &Self) -> bool {
+        self.path == other.path && self.nested == other.nested
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for MetaNameValue {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for MetaNameValue {
+    fn eq(&self, other: &Self) -> bool {
+        self.path == other.path && self.lit == other.lit
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for MethodTurbofish {}
+#[cfg(feature = "full")]
+impl PartialEq for MethodTurbofish {
+    fn eq(&self, other: &Self) -> bool {
+        self.args == other.args
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for NestedMeta {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for NestedMeta {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (NestedMeta::Meta(self0), NestedMeta::Meta(other0)) => self0 == other0,
+            (NestedMeta::Lit(self0), NestedMeta::Lit(other0)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for ParenthesizedGenericArguments {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for ParenthesizedGenericArguments {
+    fn eq(&self, other: &Self) -> bool {
+        self.inputs == other.inputs && self.output == other.output
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for Pat {}
+#[cfg(feature = "full")]
+impl PartialEq for Pat {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (Pat::Box(self0), Pat::Box(other0)) => self0 == other0,
+            (Pat::Ident(self0), Pat::Ident(other0)) => self0 == other0,
+            (Pat::Lit(self0), Pat::Lit(other0)) => self0 == other0,
+            (Pat::Macro(self0), Pat::Macro(other0)) => self0 == other0,
+            (Pat::Or(self0), Pat::Or(other0)) => self0 == other0,
+            (Pat::Path(self0), Pat::Path(other0)) => self0 == other0,
+            (Pat::Range(self0), Pat::Range(other0)) => self0 == other0,
+            (Pat::Reference(self0), Pat::Reference(other0)) => self0 == other0,
+            (Pat::Rest(self0), Pat::Rest(other0)) => self0 == other0,
+            (Pat::Slice(self0), Pat::Slice(other0)) => self0 == other0,
+            (Pat::Struct(self0), Pat::Struct(other0)) => self0 == other0,
+            (Pat::Tuple(self0), Pat::Tuple(other0)) => self0 == other0,
+            (Pat::TupleStruct(self0), Pat::TupleStruct(other0)) => self0 == other0,
+            (Pat::Type(self0), Pat::Type(other0)) => self0 == other0,
+            (Pat::Verbatim(self0), Pat::Verbatim(other0)) => {
+                TokenStreamHelper(self0) == TokenStreamHelper(other0)
+            }
+            (Pat::Wild(self0), Pat::Wild(other0)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for PatBox {}
+#[cfg(feature = "full")]
+impl PartialEq for PatBox {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.pat == other.pat
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for PatIdent {}
+#[cfg(feature = "full")]
+impl PartialEq for PatIdent {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.by_ref == other.by_ref
+            && self.mutability == other.mutability
+            && self.ident == other.ident
+            && self.subpat == other.subpat
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for PatLit {}
+#[cfg(feature = "full")]
+impl PartialEq for PatLit {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for PatMacro {}
+#[cfg(feature = "full")]
+impl PartialEq for PatMacro {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.mac == other.mac
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for PatOr {}
+#[cfg(feature = "full")]
+impl PartialEq for PatOr {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.leading_vert == other.leading_vert
+            && self.cases == other.cases
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for PatPath {}
+#[cfg(feature = "full")]
+impl PartialEq for PatPath {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.qself == other.qself && self.path == other.path
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for PatRange {}
+#[cfg(feature = "full")]
+impl PartialEq for PatRange {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.lo == other.lo
+            && self.limits == other.limits
+            && self.hi == other.hi
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for PatReference {}
+#[cfg(feature = "full")]
+impl PartialEq for PatReference {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.mutability == other.mutability && self.pat == other.pat
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for PatRest {}
+#[cfg(feature = "full")]
+impl PartialEq for PatRest {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for PatSlice {}
+#[cfg(feature = "full")]
+impl PartialEq for PatSlice {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.elems == other.elems
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for PatStruct {}
+#[cfg(feature = "full")]
+impl PartialEq for PatStruct {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.path == other.path
+            && self.fields == other.fields
+            && self.dot2_token == other.dot2_token
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for PatTuple {}
+#[cfg(feature = "full")]
+impl PartialEq for PatTuple {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.elems == other.elems
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for PatTupleStruct {}
+#[cfg(feature = "full")]
+impl PartialEq for PatTupleStruct {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.path == other.path && self.pat == other.pat
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for PatType {}
+#[cfg(feature = "full")]
+impl PartialEq for PatType {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.pat == other.pat && self.ty == other.ty
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for PatWild {}
+#[cfg(feature = "full")]
+impl PartialEq for PatWild {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for Path {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for Path {
+    fn eq(&self, other: &Self) -> bool {
+        self.leading_colon == other.leading_colon && self.segments == other.segments
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for PathArguments {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for PathArguments {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (PathArguments::None, PathArguments::None) => true,
+            (PathArguments::AngleBracketed(self0), PathArguments::AngleBracketed(other0)) => {
+                self0 == other0
+            }
+            (PathArguments::Parenthesized(self0), PathArguments::Parenthesized(other0)) => {
+                self0 == other0
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for PathSegment {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for PathSegment {
+    fn eq(&self, other: &Self) -> bool {
+        self.ident == other.ident && self.arguments == other.arguments
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for PredicateEq {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for PredicateEq {
+    fn eq(&self, other: &Self) -> bool {
+        self.lhs_ty == other.lhs_ty && self.rhs_ty == other.rhs_ty
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for PredicateLifetime {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for PredicateLifetime {
+    fn eq(&self, other: &Self) -> bool {
+        self.lifetime == other.lifetime && self.bounds == other.bounds
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for PredicateType {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for PredicateType {
+    fn eq(&self, other: &Self) -> bool {
+        self.lifetimes == other.lifetimes
+            && self.bounded_ty == other.bounded_ty
+            && self.bounds == other.bounds
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for QSelf {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for QSelf {
+    fn eq(&self, other: &Self) -> bool {
+        self.ty == other.ty && self.position == other.position && self.as_token == other.as_token
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for RangeLimits {}
+#[cfg(feature = "full")]
+impl PartialEq for RangeLimits {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (RangeLimits::HalfOpen(_), RangeLimits::HalfOpen(_)) => true,
+            (RangeLimits::Closed(_), RangeLimits::Closed(_)) => true,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for Receiver {}
+#[cfg(feature = "full")]
+impl PartialEq for Receiver {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.reference == other.reference
+            && self.mutability == other.mutability
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for ReturnType {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for ReturnType {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (ReturnType::Default, ReturnType::Default) => true,
+            (ReturnType::Type(_, self1), ReturnType::Type(_, other1)) => self1 == other1,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for Signature {}
+#[cfg(feature = "full")]
+impl PartialEq for Signature {
+    fn eq(&self, other: &Self) -> bool {
+        self.constness == other.constness
+            && self.asyncness == other.asyncness
+            && self.unsafety == other.unsafety
+            && self.abi == other.abi
+            && self.ident == other.ident
+            && self.generics == other.generics
+            && self.inputs == other.inputs
+            && self.variadic == other.variadic
+            && self.output == other.output
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for Stmt {}
+#[cfg(feature = "full")]
+impl PartialEq for Stmt {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (Stmt::Local(self0), Stmt::Local(other0)) => self0 == other0,
+            (Stmt::Item(self0), Stmt::Item(other0)) => self0 == other0,
+            (Stmt::Expr(self0), Stmt::Expr(other0)) => self0 == other0,
+            (Stmt::Semi(self0, _), Stmt::Semi(other0, _)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TraitBound {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TraitBound {
+    fn eq(&self, other: &Self) -> bool {
+        self.paren_token == other.paren_token
+            && self.modifier == other.modifier
+            && self.lifetimes == other.lifetimes
+            && self.path == other.path
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TraitBoundModifier {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TraitBoundModifier {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (TraitBoundModifier::None, TraitBoundModifier::None) => true,
+            (TraitBoundModifier::Maybe(_), TraitBoundModifier::Maybe(_)) => true,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for TraitItem {}
+#[cfg(feature = "full")]
+impl PartialEq for TraitItem {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (TraitItem::Const(self0), TraitItem::Const(other0)) => self0 == other0,
+            (TraitItem::Method(self0), TraitItem::Method(other0)) => self0 == other0,
+            (TraitItem::Type(self0), TraitItem::Type(other0)) => self0 == other0,
+            (TraitItem::Macro(self0), TraitItem::Macro(other0)) => self0 == other0,
+            (TraitItem::Verbatim(self0), TraitItem::Verbatim(other0)) => {
+                TokenStreamHelper(self0) == TokenStreamHelper(other0)
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for TraitItemConst {}
+#[cfg(feature = "full")]
+impl PartialEq for TraitItemConst {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.ident == other.ident
+            && self.ty == other.ty
+            && self.default == other.default
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for TraitItemMacro {}
+#[cfg(feature = "full")]
+impl PartialEq for TraitItemMacro {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.mac == other.mac && self.semi_token == other.semi_token
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for TraitItemMethod {}
+#[cfg(feature = "full")]
+impl PartialEq for TraitItemMethod {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.sig == other.sig
+            && self.default == other.default
+            && self.semi_token == other.semi_token
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for TraitItemType {}
+#[cfg(feature = "full")]
+impl PartialEq for TraitItemType {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.ident == other.ident
+            && self.generics == other.generics
+            && self.colon_token == other.colon_token
+            && self.bounds == other.bounds
+            && self.default == other.default
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for Type {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for Type {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (Type::Array(self0), Type::Array(other0)) => self0 == other0,
+            (Type::BareFn(self0), Type::BareFn(other0)) => self0 == other0,
+            (Type::Group(self0), Type::Group(other0)) => self0 == other0,
+            (Type::ImplTrait(self0), Type::ImplTrait(other0)) => self0 == other0,
+            (Type::Infer(self0), Type::Infer(other0)) => self0 == other0,
+            (Type::Macro(self0), Type::Macro(other0)) => self0 == other0,
+            (Type::Never(self0), Type::Never(other0)) => self0 == other0,
+            (Type::Paren(self0), Type::Paren(other0)) => self0 == other0,
+            (Type::Path(self0), Type::Path(other0)) => self0 == other0,
+            (Type::Ptr(self0), Type::Ptr(other0)) => self0 == other0,
+            (Type::Reference(self0), Type::Reference(other0)) => self0 == other0,
+            (Type::Slice(self0), Type::Slice(other0)) => self0 == other0,
+            (Type::TraitObject(self0), Type::TraitObject(other0)) => self0 == other0,
+            (Type::Tuple(self0), Type::Tuple(other0)) => self0 == other0,
+            (Type::Verbatim(self0), Type::Verbatim(other0)) => {
+                TokenStreamHelper(self0) == TokenStreamHelper(other0)
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TypeArray {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TypeArray {
+    fn eq(&self, other: &Self) -> bool {
+        self.elem == other.elem && self.len == other.len
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TypeBareFn {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TypeBareFn {
+    fn eq(&self, other: &Self) -> bool {
+        self.lifetimes == other.lifetimes
+            && self.unsafety == other.unsafety
+            && self.abi == other.abi
+            && self.inputs == other.inputs
+            && self.variadic == other.variadic
+            && self.output == other.output
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TypeGroup {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TypeGroup {
+    fn eq(&self, other: &Self) -> bool {
+        self.elem == other.elem
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TypeImplTrait {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TypeImplTrait {
+    fn eq(&self, other: &Self) -> bool {
+        self.bounds == other.bounds
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TypeInfer {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TypeInfer {
+    fn eq(&self, _other: &Self) -> bool {
+        true
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TypeMacro {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TypeMacro {
+    fn eq(&self, other: &Self) -> bool {
+        self.mac == other.mac
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TypeNever {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TypeNever {
+    fn eq(&self, _other: &Self) -> bool {
+        true
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TypeParam {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TypeParam {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.ident == other.ident
+            && self.colon_token == other.colon_token
+            && self.bounds == other.bounds
+            && self.eq_token == other.eq_token
+            && self.default == other.default
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TypeParamBound {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TypeParamBound {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (TypeParamBound::Trait(self0), TypeParamBound::Trait(other0)) => self0 == other0,
+            (TypeParamBound::Lifetime(self0), TypeParamBound::Lifetime(other0)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TypeParen {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TypeParen {
+    fn eq(&self, other: &Self) -> bool {
+        self.elem == other.elem
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TypePath {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TypePath {
+    fn eq(&self, other: &Self) -> bool {
+        self.qself == other.qself && self.path == other.path
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TypePtr {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TypePtr {
+    fn eq(&self, other: &Self) -> bool {
+        self.const_token == other.const_token
+            && self.mutability == other.mutability
+            && self.elem == other.elem
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TypeReference {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TypeReference {
+    fn eq(&self, other: &Self) -> bool {
+        self.lifetime == other.lifetime
+            && self.mutability == other.mutability
+            && self.elem == other.elem
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TypeSlice {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TypeSlice {
+    fn eq(&self, other: &Self) -> bool {
+        self.elem == other.elem
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TypeTraitObject {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TypeTraitObject {
+    fn eq(&self, other: &Self) -> bool {
+        self.dyn_token == other.dyn_token && self.bounds == other.bounds
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for TypeTuple {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for TypeTuple {
+    fn eq(&self, other: &Self) -> bool {
+        self.elems == other.elems
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for UnOp {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for UnOp {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (UnOp::Deref(_), UnOp::Deref(_)) => true,
+            (UnOp::Not(_), UnOp::Not(_)) => true,
+            (UnOp::Neg(_), UnOp::Neg(_)) => true,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for UseGlob {}
+#[cfg(feature = "full")]
+impl PartialEq for UseGlob {
+    fn eq(&self, _other: &Self) -> bool {
+        true
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for UseGroup {}
+#[cfg(feature = "full")]
+impl PartialEq for UseGroup {
+    fn eq(&self, other: &Self) -> bool {
+        self.items == other.items
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for UseName {}
+#[cfg(feature = "full")]
+impl PartialEq for UseName {
+    fn eq(&self, other: &Self) -> bool {
+        self.ident == other.ident
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for UsePath {}
+#[cfg(feature = "full")]
+impl PartialEq for UsePath {
+    fn eq(&self, other: &Self) -> bool {
+        self.ident == other.ident && self.tree == other.tree
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for UseRename {}
+#[cfg(feature = "full")]
+impl PartialEq for UseRename {
+    fn eq(&self, other: &Self) -> bool {
+        self.ident == other.ident && self.rename == other.rename
+    }
+}
+#[cfg(feature = "full")]
+impl Eq for UseTree {}
+#[cfg(feature = "full")]
+impl PartialEq for UseTree {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (UseTree::Path(self0), UseTree::Path(other0)) => self0 == other0,
+            (UseTree::Name(self0), UseTree::Name(other0)) => self0 == other0,
+            (UseTree::Rename(self0), UseTree::Rename(other0)) => self0 == other0,
+            (UseTree::Glob(self0), UseTree::Glob(other0)) => self0 == other0,
+            (UseTree::Group(self0), UseTree::Group(other0)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for Variadic {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for Variadic {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for Variant {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for Variant {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+            && self.ident == other.ident
+            && self.fields == other.fields
+            && self.discriminant == other.discriminant
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for VisCrate {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for VisCrate {
+    fn eq(&self, _other: &Self) -> bool {
+        true
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for VisPublic {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for VisPublic {
+    fn eq(&self, _other: &Self) -> bool {
+        true
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for VisRestricted {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for VisRestricted {
+    fn eq(&self, other: &Self) -> bool {
+        self.in_token == other.in_token && self.path == other.path
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for Visibility {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for Visibility {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (Visibility::Public(self0), Visibility::Public(other0)) => self0 == other0,
+            (Visibility::Crate(self0), Visibility::Crate(other0)) => self0 == other0,
+            (Visibility::Restricted(self0), Visibility::Restricted(other0)) => self0 == other0,
+            (Visibility::Inherited, Visibility::Inherited) => true,
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for WhereClause {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for WhereClause {
+    fn eq(&self, other: &Self) -> bool {
+        self.predicates == other.predicates
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Eq for WherePredicate {}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl PartialEq for WherePredicate {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (WherePredicate::Type(self0), WherePredicate::Type(other0)) => self0 == other0,
+            (WherePredicate::Lifetime(self0), WherePredicate::Lifetime(other0)) => self0 == other0,
+            (WherePredicate::Eq(self0), WherePredicate::Eq(other0)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
diff --git a/third_party/rust/syn/src/gen/fold.rs b/third_party/rust/syn/src/gen/fold.rs
--- a/third_party/rust/syn/src/gen/fold.rs
+++ b/third_party/rust/syn/src/gen/fold.rs
@@ -1,12 +1,13 @@
 // This file is @generated by syn-internal-codegen.
 // It is not intended for manual editing.
 
 #![allow(unreachable_code, unused_variables)]
+#![allow(clippy::match_wildcard_for_single_variants)]
 #[cfg(any(feature = "full", feature = "derive"))]
 use crate::gen::helper::fold::*;
 #[cfg(any(feature = "full", feature = "derive"))]
 use crate::token::{Brace, Bracket, Group, Paren};
 use crate::*;
 use proc_macro2::Span;
 #[cfg(feature = "full")]
 macro_rules! full {
@@ -21,17 +22,17 @@ macro_rules! full {
     };
 }
 /// Syntax tree traversal to transform the nodes of an owned syntax tree.
 ///
 /// See the [module documentation] for details.
 ///
 /// [module documentation]: self
 ///
-/// *This trait is available if Syn is built with the `"fold"` feature.*
+/// *This trait is available only if Syn is built with the `"fold"` feature.*
 pub trait Fold {
     #[cfg(any(feature = "derive", feature = "full"))]
     fn fold_abi(&mut self, i: Abi) -> Abi {
         fold_abi(self, i)
     }
     #[cfg(any(feature = "derive", feature = "full"))]
     fn fold_angle_bracketed_generic_arguments(
         &mut self,
@@ -428,45 +429,37 @@ pub trait Fold {
     }
     fn fold_lifetime(&mut self, i: Lifetime) -> Lifetime {
         fold_lifetime(self, i)
     }
     #[cfg(any(feature = "derive", feature = "full"))]
     fn fold_lifetime_def(&mut self, i: LifetimeDef) -> LifetimeDef {
         fold_lifetime_def(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn fold_lit(&mut self, i: Lit) -> Lit {
         fold_lit(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn fold_lit_bool(&mut self, i: LitBool) -> LitBool {
         fold_lit_bool(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn fold_lit_byte(&mut self, i: LitByte) -> LitByte {
         fold_lit_byte(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn fold_lit_byte_str(&mut self, i: LitByteStr) -> LitByteStr {
         fold_lit_byte_str(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn fold_lit_char(&mut self, i: LitChar) -> LitChar {
         fold_lit_char(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn fold_lit_float(&mut self, i: LitFloat) -> LitFloat {
         fold_lit_float(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn fold_lit_int(&mut self, i: LitInt) -> LitInt {
         fold_lit_int(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn fold_lit_str(&mut self, i: LitStr) -> LitStr {
         fold_lit_str(self, i)
     }
     #[cfg(feature = "full")]
     fn fold_local(&mut self, i: Local) -> Local {
         fold_local(self, i)
     }
     #[cfg(any(feature = "derive", feature = "full"))]
@@ -794,39 +787,39 @@ where
 pub fn fold_angle_bracketed_generic_arguments<F>(
     f: &mut F,
     node: AngleBracketedGenericArguments,
 ) -> AngleBracketedGenericArguments
 where
     F: Fold + ?Sized,
 {
     AngleBracketedGenericArguments {
-        colon2_token: (node.colon2_token).map(|it| Token ! [ :: ](tokens_helper(f, &it.spans))),
-        lt_token: Token ! [ < ](tokens_helper(f, &node.lt_token.spans)),
+        colon2_token: (node.colon2_token).map(|it| Token ! [::](tokens_helper(f, &it.spans))),
+        lt_token: Token ! [<](tokens_helper(f, &node.lt_token.spans)),
         args: FoldHelper::lift(node.args, |it| f.fold_generic_argument(it)),
-        gt_token: Token ! [ > ](tokens_helper(f, &node.gt_token.spans)),
+        gt_token: Token ! [>](tokens_helper(f, &node.gt_token.spans)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_arm<F>(f: &mut F, node: Arm) -> Arm
 where
     F: Fold + ?Sized,
 {
     Arm {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         pat: f.fold_pat(node.pat),
         guard: (node.guard).map(|it| {
             (
                 Token![if](tokens_helper(f, &(it).0.span)),
                 Box::new(f.fold_expr(*(it).1)),
             )
         }),
-        fat_arrow_token: Token ! [ => ](tokens_helper(f, &node.fat_arrow_token.spans)),
+        fat_arrow_token: Token ! [=>](tokens_helper(f, &node.fat_arrow_token.spans)),
         body: Box::new(f.fold_expr(*node.body)),
-        comma: (node.comma).map(|it| Token ! [ , ](tokens_helper(f, &it.spans))),
+        comma: (node.comma).map(|it| Token ! [,](tokens_helper(f, &it.spans))),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_attr_style<F>(f: &mut F, node: AttrStyle) -> AttrStyle
 where
     F: Fold + ?Sized,
 {
     match node {
@@ -837,109 +830,97 @@ where
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_attribute<F>(f: &mut F, node: Attribute) -> Attribute
 where
     F: Fold + ?Sized,
 {
     Attribute {
-        pound_token: Token ! [ # ](tokens_helper(f, &node.pound_token.spans)),
+        pound_token: Token ! [#](tokens_helper(f, &node.pound_token.spans)),
         style: f.fold_attr_style(node.style),
         bracket_token: Bracket(tokens_helper(f, &node.bracket_token.span)),
         path: f.fold_path(node.path),
         tokens: node.tokens,
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_bare_fn_arg<F>(f: &mut F, node: BareFnArg) -> BareFnArg
 where
     F: Fold + ?Sized,
 {
     BareFnArg {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         name: (node.name).map(|it| {
             (
                 f.fold_ident((it).0),
-                Token ! [ : ](tokens_helper(f, &(it).1.spans)),
+                Token ! [:](tokens_helper(f, &(it).1.spans)),
             )
         }),
         ty: f.fold_type(node.ty),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_bin_op<F>(f: &mut F, node: BinOp) -> BinOp
 where
     F: Fold + ?Sized,
 {
     match node {
-        BinOp::Add(_binding_0) => BinOp::Add(Token ! [ + ](tokens_helper(f, &_binding_0.spans))),
-        BinOp::Sub(_binding_0) => BinOp::Sub(Token ! [ - ](tokens_helper(f, &_binding_0.spans))),
-        BinOp::Mul(_binding_0) => BinOp::Mul(Token ! [ * ](tokens_helper(f, &_binding_0.spans))),
-        BinOp::Div(_binding_0) => BinOp::Div(Token ! [ / ](tokens_helper(f, &_binding_0.spans))),
-        BinOp::Rem(_binding_0) => BinOp::Rem(Token ! [ % ](tokens_helper(f, &_binding_0.spans))),
-        BinOp::And(_binding_0) => BinOp::And(Token ! [ && ](tokens_helper(f, &_binding_0.spans))),
-        BinOp::Or(_binding_0) => BinOp::Or(Token ! [ || ](tokens_helper(f, &_binding_0.spans))),
+        BinOp::Add(_binding_0) => BinOp::Add(Token ! [+](tokens_helper(f, &_binding_0.spans))),
+        BinOp::Sub(_binding_0) => BinOp::Sub(Token ! [-](tokens_helper(f, &_binding_0.spans))),
+        BinOp::Mul(_binding_0) => BinOp::Mul(Token ! [*](tokens_helper(f, &_binding_0.spans))),
+        BinOp::Div(_binding_0) => BinOp::Div(Token ! [/](tokens_helper(f, &_binding_0.spans))),
+        BinOp::Rem(_binding_0) => BinOp::Rem(Token ! [%](tokens_helper(f, &_binding_0.spans))),
+        BinOp::And(_binding_0) => BinOp::And(Token ! [&&](tokens_helper(f, &_binding_0.spans))),
+        BinOp::Or(_binding_0) => BinOp::Or(Token ! [||](tokens_helper(f, &_binding_0.spans))),
         BinOp::BitXor(_binding_0) => {
-            BinOp::BitXor(Token ! [ ^ ](tokens_helper(f, &_binding_0.spans)))
+            BinOp::BitXor(Token ! [^](tokens_helper(f, &_binding_0.spans)))
         }
         BinOp::BitAnd(_binding_0) => {
-            BinOp::BitAnd(Token ! [ & ](tokens_helper(f, &_binding_0.spans)))
-        }
-        BinOp::BitOr(_binding_0) => {
-            BinOp::BitOr(Token ! [ | ](tokens_helper(f, &_binding_0.spans)))
+            BinOp::BitAnd(Token ! [&](tokens_helper(f, &_binding_0.spans)))
         }
-        BinOp::Shl(_binding_0) => BinOp::Shl(Token ! [ << ](tokens_helper(f, &_binding_0.spans))),
-        BinOp::Shr(_binding_0) => BinOp::Shr(Token ! [ >> ](tokens_helper(f, &_binding_0.spans))),
-        BinOp::Eq(_binding_0) => BinOp::Eq(Token ! [ == ](tokens_helper(f, &_binding_0.spans))),
-        BinOp::Lt(_binding_0) => BinOp::Lt(Token ! [ < ](tokens_helper(f, &_binding_0.spans))),
-        BinOp::Le(_binding_0) => BinOp::Le(Token ! [ <= ](tokens_helper(f, &_binding_0.spans))),
-        BinOp::Ne(_binding_0) => BinOp::Ne(Token ! [ != ](tokens_helper(f, &_binding_0.spans))),
-        BinOp::Ge(_binding_0) => BinOp::Ge(Token ! [ >= ](tokens_helper(f, &_binding_0.spans))),
-        BinOp::Gt(_binding_0) => BinOp::Gt(Token ! [ > ](tokens_helper(f, &_binding_0.spans))),
-        BinOp::AddEq(_binding_0) => {
-            BinOp::AddEq(Token ! [ += ](tokens_helper(f, &_binding_0.spans)))
-        }
-        BinOp::SubEq(_binding_0) => {
-            BinOp::SubEq(Token ! [ -= ](tokens_helper(f, &_binding_0.spans)))
-        }
-        BinOp::MulEq(_binding_0) => {
-            BinOp::MulEq(Token ! [ *= ](tokens_helper(f, &_binding_0.spans)))
-        }
-        BinOp::DivEq(_binding_0) => {
-            BinOp::DivEq(Token ! [ /= ](tokens_helper(f, &_binding_0.spans)))
-        }
-        BinOp::RemEq(_binding_0) => {
-            BinOp::RemEq(Token ! [ %= ](tokens_helper(f, &_binding_0.spans)))
-        }
+        BinOp::BitOr(_binding_0) => BinOp::BitOr(Token ! [|](tokens_helper(f, &_binding_0.spans))),
+        BinOp::Shl(_binding_0) => BinOp::Shl(Token ! [<<](tokens_helper(f, &_binding_0.spans))),
+        BinOp::Shr(_binding_0) => BinOp::Shr(Token ! [>>](tokens_helper(f, &_binding_0.spans))),
+        BinOp::Eq(_binding_0) => BinOp::Eq(Token ! [==](tokens_helper(f, &_binding_0.spans))),
+        BinOp::Lt(_binding_0) => BinOp::Lt(Token ! [<](tokens_helper(f, &_binding_0.spans))),
+        BinOp::Le(_binding_0) => BinOp::Le(Token ! [<=](tokens_helper(f, &_binding_0.spans))),
+        BinOp::Ne(_binding_0) => BinOp::Ne(Token ! [!=](tokens_helper(f, &_binding_0.spans))),
+        BinOp::Ge(_binding_0) => BinOp::Ge(Token ! [>=](tokens_helper(f, &_binding_0.spans))),
+        BinOp::Gt(_binding_0) => BinOp::Gt(Token ! [>](tokens_helper(f, &_binding_0.spans))),
+        BinOp::AddEq(_binding_0) => BinOp::AddEq(Token ! [+=](tokens_helper(f, &_binding_0.spans))),
+        BinOp::SubEq(_binding_0) => BinOp::SubEq(Token ! [-=](tokens_helper(f, &_binding_0.spans))),
+        BinOp::MulEq(_binding_0) => BinOp::MulEq(Token ! [*=](tokens_helper(f, &_binding_0.spans))),
+        BinOp::DivEq(_binding_0) => BinOp::DivEq(Token ! [/=](tokens_helper(f, &_binding_0.spans))),
+        BinOp::RemEq(_binding_0) => BinOp::RemEq(Token ! [%=](tokens_helper(f, &_binding_0.spans))),
         BinOp::BitXorEq(_binding_0) => {
-            BinOp::BitXorEq(Token ! [ ^= ](tokens_helper(f, &_binding_0.spans)))
+            BinOp::BitXorEq(Token ! [^=](tokens_helper(f, &_binding_0.spans)))
         }
         BinOp::BitAndEq(_binding_0) => {
-            BinOp::BitAndEq(Token ! [ &= ](tokens_helper(f, &_binding_0.spans)))
+            BinOp::BitAndEq(Token ! [&=](tokens_helper(f, &_binding_0.spans)))
         }
         BinOp::BitOrEq(_binding_0) => {
-            BinOp::BitOrEq(Token ! [ |= ](tokens_helper(f, &_binding_0.spans)))
+            BinOp::BitOrEq(Token ! [|=](tokens_helper(f, &_binding_0.spans)))
         }
         BinOp::ShlEq(_binding_0) => {
-            BinOp::ShlEq(Token ! [ <<= ](tokens_helper(f, &_binding_0.spans)))
+            BinOp::ShlEq(Token ! [<<=](tokens_helper(f, &_binding_0.spans)))
         }
         BinOp::ShrEq(_binding_0) => {
-            BinOp::ShrEq(Token ! [ >>= ](tokens_helper(f, &_binding_0.spans)))
+            BinOp::ShrEq(Token ! [>>=](tokens_helper(f, &_binding_0.spans)))
         }
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_binding<F>(f: &mut F, node: Binding) -> Binding
 where
     F: Fold + ?Sized,
 {
     Binding {
         ident: f.fold_ident(node.ident),
-        eq_token: Token ! [ = ](tokens_helper(f, &node.eq_token.spans)),
+        eq_token: Token ! [=](tokens_helper(f, &node.eq_token.spans)),
         ty: f.fold_type(node.ty),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_block<F>(f: &mut F, node: Block) -> Block
 where
     F: Fold + ?Sized,
 {
@@ -950,44 +931,44 @@ where
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_bound_lifetimes<F>(f: &mut F, node: BoundLifetimes) -> BoundLifetimes
 where
     F: Fold + ?Sized,
 {
     BoundLifetimes {
         for_token: Token![for](tokens_helper(f, &node.for_token.span)),
-        lt_token: Token ! [ < ](tokens_helper(f, &node.lt_token.spans)),
+        lt_token: Token ! [<](tokens_helper(f, &node.lt_token.spans)),
         lifetimes: FoldHelper::lift(node.lifetimes, |it| f.fold_lifetime_def(it)),
-        gt_token: Token ! [ > ](tokens_helper(f, &node.gt_token.spans)),
+        gt_token: Token ! [>](tokens_helper(f, &node.gt_token.spans)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_const_param<F>(f: &mut F, node: ConstParam) -> ConstParam
 where
     F: Fold + ?Sized,
 {
     ConstParam {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         const_token: Token![const](tokens_helper(f, &node.const_token.span)),
         ident: f.fold_ident(node.ident),
-        colon_token: Token ! [ : ](tokens_helper(f, &node.colon_token.spans)),
+        colon_token: Token ! [:](tokens_helper(f, &node.colon_token.spans)),
         ty: f.fold_type(node.ty),
-        eq_token: (node.eq_token).map(|it| Token ! [ = ](tokens_helper(f, &it.spans))),
+        eq_token: (node.eq_token).map(|it| Token ! [=](tokens_helper(f, &it.spans))),
         default: (node.default).map(|it| f.fold_expr(it)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_constraint<F>(f: &mut F, node: Constraint) -> Constraint
 where
     F: Fold + ?Sized,
 {
     Constraint {
         ident: f.fold_ident(node.ident),
-        colon_token: Token ! [ : ](tokens_helper(f, &node.colon_token.spans)),
+        colon_token: Token ! [:](tokens_helper(f, &node.colon_token.spans)),
         bounds: FoldHelper::lift(node.bounds, |it| f.fold_type_param_bound(it)),
     }
 }
 #[cfg(feature = "derive")]
 pub fn fold_data<F>(f: &mut F, node: Data) -> Data
 where
     F: Fold + ?Sized,
 {
@@ -1011,17 +992,17 @@ where
 #[cfg(feature = "derive")]
 pub fn fold_data_struct<F>(f: &mut F, node: DataStruct) -> DataStruct
 where
     F: Fold + ?Sized,
 {
     DataStruct {
         struct_token: Token![struct](tokens_helper(f, &node.struct_token.span)),
         fields: f.fold_fields(node.fields),
-        semi_token: (node.semi_token).map(|it| Token ! [ ; ](tokens_helper(f, &it.spans))),
+        semi_token: (node.semi_token).map(|it| Token ! [;](tokens_helper(f, &it.spans))),
     }
 }
 #[cfg(feature = "derive")]
 pub fn fold_data_union<F>(f: &mut F, node: DataUnion) -> DataUnion
 where
     F: Fold + ?Sized,
 {
     DataUnion {
@@ -1107,17 +1088,17 @@ where
 #[cfg(feature = "full")]
 pub fn fold_expr_assign<F>(f: &mut F, node: ExprAssign) -> ExprAssign
 where
     F: Fold + ?Sized,
 {
     ExprAssign {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         left: Box::new(f.fold_expr(*node.left)),
-        eq_token: Token ! [ = ](tokens_helper(f, &node.eq_token.spans)),
+        eq_token: Token ! [=](tokens_helper(f, &node.eq_token.spans)),
         right: Box::new(f.fold_expr(*node.right)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_expr_assign_op<F>(f: &mut F, node: ExprAssignOp) -> ExprAssignOp
 where
     F: Fold + ?Sized,
 {
@@ -1143,17 +1124,17 @@ where
 #[cfg(feature = "full")]
 pub fn fold_expr_await<F>(f: &mut F, node: ExprAwait) -> ExprAwait
 where
     F: Fold + ?Sized,
 {
     ExprAwait {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         base: Box::new(f.fold_expr(*node.base)),
-        dot_token: Token ! [ . ](tokens_helper(f, &node.dot_token.spans)),
+        dot_token: Token ! [.](tokens_helper(f, &node.dot_token.spans)),
         await_token: crate::token::Await(tokens_helper(f, &node.await_token.span)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_expr_binary<F>(f: &mut F, node: ExprBinary) -> ExprBinary
 where
     F: Fold + ?Sized,
 {
@@ -1227,19 +1208,19 @@ pub fn fold_expr_closure<F>(f: &mut F, n
 where
     F: Fold + ?Sized,
 {
     ExprClosure {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         asyncness: (node.asyncness).map(|it| Token![async](tokens_helper(f, &it.span))),
         movability: (node.movability).map(|it| Token![static](tokens_helper(f, &it.span))),
         capture: (node.capture).map(|it| Token![move](tokens_helper(f, &it.span))),
-        or1_token: Token ! [ | ](tokens_helper(f, &node.or1_token.spans)),
+        or1_token: Token ! [|](tokens_helper(f, &node.or1_token.spans)),
         inputs: FoldHelper::lift(node.inputs, |it| f.fold_pat(it)),
-        or2_token: Token ! [ | ](tokens_helper(f, &node.or2_token.spans)),
+        or2_token: Token ! [|](tokens_helper(f, &node.or2_token.spans)),
         output: f.fold_return_type(node.output),
         body: Box::new(f.fold_expr(*node.body)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_expr_continue<F>(f: &mut F, node: ExprContinue) -> ExprContinue
 where
     F: Fold + ?Sized,
@@ -1253,17 +1234,17 @@ where
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_expr_field<F>(f: &mut F, node: ExprField) -> ExprField
 where
     F: Fold + ?Sized,
 {
     ExprField {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         base: Box::new(f.fold_expr(*node.base)),
-        dot_token: Token ! [ . ](tokens_helper(f, &node.dot_token.spans)),
+        dot_token: Token ! [.](tokens_helper(f, &node.dot_token.spans)),
         member: f.fold_member(node.member),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_expr_for_loop<F>(f: &mut F, node: ExprForLoop) -> ExprForLoop
 where
     F: Fold + ?Sized,
 {
@@ -1322,17 +1303,17 @@ where
 pub fn fold_expr_let<F>(f: &mut F, node: ExprLet) -> ExprLet
 where
     F: Fold + ?Sized,
 {
     ExprLet {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         let_token: Token![let](tokens_helper(f, &node.let_token.span)),
         pat: f.fold_pat(node.pat),
-        eq_token: Token ! [ = ](tokens_helper(f, &node.eq_token.spans)),
+        eq_token: Token ! [=](tokens_helper(f, &node.eq_token.spans)),
         expr: Box::new(f.fold_expr(*node.expr)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_expr_lit<F>(f: &mut F, node: ExprLit) -> ExprLit
 where
     F: Fold + ?Sized,
 {
@@ -1379,17 +1360,17 @@ where
 #[cfg(feature = "full")]
 pub fn fold_expr_method_call<F>(f: &mut F, node: ExprMethodCall) -> ExprMethodCall
 where
     F: Fold + ?Sized,
 {
     ExprMethodCall {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         receiver: Box::new(f.fold_expr(*node.receiver)),
-        dot_token: Token ! [ . ](tokens_helper(f, &node.dot_token.spans)),
+        dot_token: Token ! [.](tokens_helper(f, &node.dot_token.spans)),
         method: f.fold_ident(node.method),
         turbofish: (node.turbofish).map(|it| f.fold_method_turbofish(it)),
         paren_token: Paren(tokens_helper(f, &node.paren_token.span)),
         args: FoldHelper::lift(node.args, |it| f.fold_expr(it)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_expr_paren<F>(f: &mut F, node: ExprParen) -> ExprParen
@@ -1427,32 +1408,32 @@ where
 }
 #[cfg(feature = "full")]
 pub fn fold_expr_reference<F>(f: &mut F, node: ExprReference) -> ExprReference
 where
     F: Fold + ?Sized,
 {
     ExprReference {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
-        and_token: Token ! [ & ](tokens_helper(f, &node.and_token.spans)),
+        and_token: Token ! [&](tokens_helper(f, &node.and_token.spans)),
         raw: node.raw,
         mutability: (node.mutability).map(|it| Token![mut](tokens_helper(f, &it.span))),
         expr: Box::new(f.fold_expr(*node.expr)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_expr_repeat<F>(f: &mut F, node: ExprRepeat) -> ExprRepeat
 where
     F: Fold + ?Sized,
 {
     ExprRepeat {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         bracket_token: Bracket(tokens_helper(f, &node.bracket_token.span)),
         expr: Box::new(f.fold_expr(*node.expr)),
-        semi_token: Token ! [ ; ](tokens_helper(f, &node.semi_token.spans)),
+        semi_token: Token ! [;](tokens_helper(f, &node.semi_token.spans)),
         len: Box::new(f.fold_expr(*node.len)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_expr_return<F>(f: &mut F, node: ExprReturn) -> ExprReturn
 where
     F: Fold + ?Sized,
 {
@@ -1479,17 +1460,17 @@ where
 #[cfg(feature = "full")]
 pub fn fold_expr_try<F>(f: &mut F, node: ExprTry) -> ExprTry
 where
     F: Fold + ?Sized,
 {
     ExprTry {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         expr: Box::new(f.fold_expr(*node.expr)),
-        question_token: Token ! [ ? ](tokens_helper(f, &node.question_token.spans)),
+        question_token: Token ! [?](tokens_helper(f, &node.question_token.spans)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_expr_try_block<F>(f: &mut F, node: ExprTryBlock) -> ExprTryBlock
 where
     F: Fold + ?Sized,
 {
     ExprTryBlock {
@@ -1512,17 +1493,17 @@ where
 #[cfg(feature = "full")]
 pub fn fold_expr_type<F>(f: &mut F, node: ExprType) -> ExprType
 where
     F: Fold + ?Sized,
 {
     ExprType {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         expr: Box::new(f.fold_expr(*node.expr)),
-        colon_token: Token ! [ : ](tokens_helper(f, &node.colon_token.spans)),
+        colon_token: Token ! [:](tokens_helper(f, &node.colon_token.spans)),
         ty: Box::new(f.fold_type(*node.ty)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_expr_unary<F>(f: &mut F, node: ExprUnary) -> ExprUnary
 where
     F: Fold + ?Sized,
 {
@@ -1571,41 +1552,41 @@ where
 pub fn fold_field<F>(f: &mut F, node: Field) -> Field
 where
     F: Fold + ?Sized,
 {
     Field {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         vis: f.fold_visibility(node.vis),
         ident: (node.ident).map(|it| f.fold_ident(it)),
-        colon_token: (node.colon_token).map(|it| Token ! [ : ](tokens_helper(f, &it.spans))),
+        colon_token: (node.colon_token).map(|it| Token ! [:](tokens_helper(f, &it.spans))),
         ty: f.fold_type(node.ty),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_field_pat<F>(f: &mut F, node: FieldPat) -> FieldPat
 where
     F: Fold + ?Sized,
 {
     FieldPat {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         member: f.fold_member(node.member),
-        colon_token: (node.colon_token).map(|it| Token ! [ : ](tokens_helper(f, &it.spans))),
+        colon_token: (node.colon_token).map(|it| Token ! [:](tokens_helper(f, &it.spans))),
         pat: Box::new(f.fold_pat(*node.pat)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_field_value<F>(f: &mut F, node: FieldValue) -> FieldValue
 where
     F: Fold + ?Sized,
 {
     FieldValue {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         member: f.fold_member(node.member),
-        colon_token: (node.colon_token).map(|it| Token ! [ : ](tokens_helper(f, &it.spans))),
+        colon_token: (node.colon_token).map(|it| Token ! [:](tokens_helper(f, &it.spans))),
         expr: f.fold_expr(node.expr),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_fields<F>(f: &mut F, node: Fields) -> Fields
 where
     F: Fold + ?Sized,
 {
@@ -1676,57 +1657,57 @@ where
 pub fn fold_foreign_item_fn<F>(f: &mut F, node: ForeignItemFn) -> ForeignItemFn
 where
     F: Fold + ?Sized,
 {
     ForeignItemFn {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         vis: f.fold_visibility(node.vis),
         sig: f.fold_signature(node.sig),
-        semi_token: Token ! [ ; ](tokens_helper(f, &node.semi_token.spans)),
+        semi_token: Token ! [;](tokens_helper(f, &node.semi_token.spans)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_foreign_item_macro<F>(f: &mut F, node: ForeignItemMacro) -> ForeignItemMacro
 where
     F: Fold + ?Sized,
 {
     ForeignItemMacro {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         mac: f.fold_macro(node.mac),
-        semi_token: (node.semi_token).map(|it| Token ! [ ; ](tokens_helper(f, &it.spans))),
+        semi_token: (node.semi_token).map(|it| Token ! [;](tokens_helper(f, &it.spans))),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_foreign_item_static<F>(f: &mut F, node: ForeignItemStatic) -> ForeignItemStatic
 where
     F: Fold + ?Sized,
 {
     ForeignItemStatic {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         vis: f.fold_visibility(node.vis),
         static_token: Token![static](tokens_helper(f, &node.static_token.span)),
         mutability: (node.mutability).map(|it| Token![mut](tokens_helper(f, &it.span))),
         ident: f.fold_ident(node.ident),
-        colon_token: Token ! [ : ](tokens_helper(f, &node.colon_token.spans)),
+        colon_token: Token ! [:](tokens_helper(f, &node.colon_token.spans)),
         ty: Box::new(f.fold_type(*node.ty)),
-        semi_token: Token ! [ ; ](tokens_helper(f, &node.semi_token.spans)),
+        semi_token: Token ! [;](tokens_helper(f, &node.semi_token.spans)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_foreign_item_type<F>(f: &mut F, node: ForeignItemType) -> ForeignItemType
 where
     F: Fold + ?Sized,
 {
     ForeignItemType {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         vis: f.fold_visibility(node.vis),
         type_token: Token![type](tokens_helper(f, &node.type_token.span)),
         ident: f.fold_ident(node.ident),
-        semi_token: Token ! [ ; ](tokens_helper(f, &node.semi_token.spans)),
+        semi_token: Token ! [;](tokens_helper(f, &node.semi_token.spans)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_generic_argument<F>(f: &mut F, node: GenericArgument) -> GenericArgument
 where
     F: Fold + ?Sized,
 {
     match node {
@@ -1774,19 +1755,19 @@ where
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_generics<F>(f: &mut F, node: Generics) -> Generics
 where
     F: Fold + ?Sized,
 {
     Generics {
-        lt_token: (node.lt_token).map(|it| Token ! [ < ](tokens_helper(f, &it.spans))),
+        lt_token: (node.lt_token).map(|it| Token ! [<](tokens_helper(f, &it.spans))),
         params: FoldHelper::lift(node.params, |it| f.fold_generic_param(it)),
-        gt_token: (node.gt_token).map(|it| Token ! [ > ](tokens_helper(f, &it.spans))),
+        gt_token: (node.gt_token).map(|it| Token ! [>](tokens_helper(f, &it.spans))),
         where_clause: (node.where_clause).map(|it| f.fold_where_clause(it)),
     }
 }
 pub fn fold_ident<F>(f: &mut F, node: Ident) -> Ident
 where
     F: Fold + ?Sized,
 {
     let mut node = node;
@@ -1814,32 +1795,32 @@ where
     F: Fold + ?Sized,
 {
     ImplItemConst {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         vis: f.fold_visibility(node.vis),
         defaultness: (node.defaultness).map(|it| Token![default](tokens_helper(f, &it.span))),
         const_token: Token![const](tokens_helper(f, &node.const_token.span)),
         ident: f.fold_ident(node.ident),
-        colon_token: Token ! [ : ](tokens_helper(f, &node.colon_token.spans)),
+        colon_token: Token ! [:](tokens_helper(f, &node.colon_token.spans)),
         ty: f.fold_type(node.ty),
-        eq_token: Token ! [ = ](tokens_helper(f, &node.eq_token.spans)),
+        eq_token: Token ! [=](tokens_helper(f, &node.eq_token.spans)),
         expr: f.fold_expr(node.expr),
-        semi_token: Token ! [ ; ](tokens_helper(f, &node.semi_token.spans)),
+        semi_token: Token ! [;](tokens_helper(f, &node.semi_token.spans)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_impl_item_macro<F>(f: &mut F, node: ImplItemMacro) -> ImplItemMacro
 where
     F: Fold + ?Sized,
 {
     ImplItemMacro {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         mac: f.fold_macro(node.mac),
-        semi_token: (node.semi_token).map(|it| Token ! [ ; ](tokens_helper(f, &it.spans))),
+        semi_token: (node.semi_token).map(|it| Token ! [;](tokens_helper(f, &it.spans))),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_impl_item_method<F>(f: &mut F, node: ImplItemMethod) -> ImplItemMethod
 where
     F: Fold + ?Sized,
 {
     ImplItemMethod {
@@ -1857,19 +1838,19 @@ where
 {
     ImplItemType {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         vis: f.fold_visibility(node.vis),
         defaultness: (node.defaultness).map(|it| Token![default](tokens_helper(f, &it.span))),
         type_token: Token![type](tokens_helper(f, &node.type_token.span)),
         ident: f.fold_ident(node.ident),
         generics: f.fold_generics(node.generics),
-        eq_token: Token ! [ = ](tokens_helper(f, &node.eq_token.spans)),
+        eq_token: Token ! [=](tokens_helper(f, &node.eq_token.spans)),
         ty: f.fold_type(node.ty),
-        semi_token: Token ! [ ; ](tokens_helper(f, &node.semi_token.spans)),
+        semi_token: Token ! [;](tokens_helper(f, &node.semi_token.spans)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_index<F>(f: &mut F, node: Index) -> Index
 where
     F: Fold + ?Sized,
 {
     Index {
@@ -1908,21 +1889,21 @@ pub fn fold_item_const<F>(f: &mut F, nod
 where
     F: Fold + ?Sized,
 {
     ItemConst {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         vis: f.fold_visibility(node.vis),
         const_token: Token![const](tokens_helper(f, &node.const_token.span)),
         ident: f.fold_ident(node.ident),
-        colon_token: Token ! [ : ](tokens_helper(f, &node.colon_token.spans)),
+        colon_token: Token ! [:](tokens_helper(f, &node.colon_token.spans)),
         ty: Box::new(f.fold_type(*node.ty)),
-        eq_token: Token ! [ = ](tokens_helper(f, &node.eq_token.spans)),
+        eq_token: Token ! [=](tokens_helper(f, &node.eq_token.spans)),
         expr: Box::new(f.fold_expr(*node.expr)),
-        semi_token: Token ! [ ; ](tokens_helper(f, &node.semi_token.spans)),
+        semi_token: Token ! [;](tokens_helper(f, &node.semi_token.spans)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_item_enum<F>(f: &mut F, node: ItemEnum) -> ItemEnum
 where
     F: Fold + ?Sized,
 {
     ItemEnum {
@@ -1947,17 +1928,17 @@ where
         crate_token: Token![crate](tokens_helper(f, &node.crate_token.span)),
         ident: f.fold_ident(node.ident),
         rename: (node.rename).map(|it| {
             (
                 Token![as](tokens_helper(f, &(it).0.span)),
                 f.fold_ident((it).1),
             )
         }),
-        semi_token: Token ! [ ; ](tokens_helper(f, &node.semi_token.spans)),
+        semi_token: Token ! [;](tokens_helper(f, &node.semi_token.spans)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_item_fn<F>(f: &mut F, node: ItemFn) -> ItemFn
 where
     F: Fold + ?Sized,
 {
     ItemFn {
@@ -2006,17 +1987,17 @@ where
 pub fn fold_item_macro<F>(f: &mut F, node: ItemMacro) -> ItemMacro
 where
     F: Fold + ?Sized,
 {
     ItemMacro {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         ident: (node.ident).map(|it| f.fold_ident(it)),
         mac: f.fold_macro(node.mac),
-        semi_token: (node.semi_token).map(|it| Token ! [ ; ](tokens_helper(f, &it.spans))),
+        semi_token: (node.semi_token).map(|it| Token ! [;](tokens_helper(f, &it.spans))),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_item_macro2<F>(f: &mut F, node: ItemMacro2) -> ItemMacro2
 where
     F: Fold + ?Sized,
 {
     ItemMacro2 {
@@ -2038,101 +2019,101 @@ where
         mod_token: Token![mod](tokens_helper(f, &node.mod_token.span)),
         ident: f.fold_ident(node.ident),
         content: (node.content).map(|it| {
             (
                 Brace(tokens_helper(f, &(it).0.span)),
                 FoldHelper::lift((it).1, |it| f.fold_item(it)),
             )
         }),
-        semi: (node.semi).map(|it| Token ! [ ; ](tokens_helper(f, &it.spans))),
+        semi: (node.semi).map(|it| Token ! [;](tokens_helper(f, &it.spans))),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_item_static<F>(f: &mut F, node: ItemStatic) -> ItemStatic
 where
     F: Fold + ?Sized,
 {
     ItemStatic {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         vis: f.fold_visibility(node.vis),
         static_token: Token![static](tokens_helper(f, &node.static_token.span)),
         mutability: (node.mutability).map(|it| Token![mut](tokens_helper(f, &it.span))),
         ident: f.fold_ident(node.ident),
-        colon_token: Token ! [ : ](tokens_helper(f, &node.colon_token.spans)),
+        colon_token: Token ! [:](tokens_helper(f, &node.colon_token.spans)),
         ty: Box::new(f.fold_type(*node.ty)),
-        eq_token: Token ! [ = ](tokens_helper(f, &node.eq_token.spans)),
+        eq_token: Token ! [=](tokens_helper(f, &node.eq_token.spans)),
         expr: Box::new(f.fold_expr(*node.expr)),
-        semi_token: Token ! [ ; ](tokens_helper(f, &node.semi_token.spans)),
+        semi_token: Token ! [;](tokens_helper(f, &node.semi_token.spans)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_item_struct<F>(f: &mut F, node: ItemStruct) -> ItemStruct
 where
     F: Fold + ?Sized,
 {
     ItemStruct {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         vis: f.fold_visibility(node.vis),
         struct_token: Token![struct](tokens_helper(f, &node.struct_token.span)),
         ident: f.fold_ident(node.ident),
         generics: f.fold_generics(node.generics),
         fields: f.fold_fields(node.fields),
-        semi_token: (node.semi_token).map(|it| Token ! [ ; ](tokens_helper(f, &it.spans))),
+        semi_token: (node.semi_token).map(|it| Token ! [;](tokens_helper(f, &it.spans))),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_item_trait<F>(f: &mut F, node: ItemTrait) -> ItemTrait
 where
     F: Fold + ?Sized,
 {
     ItemTrait {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         vis: f.fold_visibility(node.vis),
         unsafety: (node.unsafety).map(|it| Token![unsafe](tokens_helper(f, &it.span))),
         auto_token: (node.auto_token).map(|it| Token![auto](tokens_helper(f, &it.span))),
         trait_token: Token![trait](tokens_helper(f, &node.trait_token.span)),
         ident: f.fold_ident(node.ident),
         generics: f.fold_generics(node.generics),
-        colon_token: (node.colon_token).map(|it| Token ! [ : ](tokens_helper(f, &it.spans))),
+        colon_token: (node.colon_token).map(|it| Token ! [:](tokens_helper(f, &it.spans))),
         supertraits: FoldHelper::lift(node.supertraits, |it| f.fold_type_param_bound(it)),
         brace_token: Brace(tokens_helper(f, &node.brace_token.span)),
         items: FoldHelper::lift(node.items, |it| f.fold_trait_item(it)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_item_trait_alias<F>(f: &mut F, node: ItemTraitAlias) -> ItemTraitAlias
 where
     F: Fold + ?Sized,
 {
     ItemTraitAlias {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         vis: f.fold_visibility(node.vis),
         trait_token: Token![trait](tokens_helper(f, &node.trait_token.span)),
         ident: f.fold_ident(node.ident),
         generics: f.fold_generics(node.generics),
-        eq_token: Token ! [ = ](tokens_helper(f, &node.eq_token.spans)),
+        eq_token: Token ! [=](tokens_helper(f, &node.eq_token.spans)),
         bounds: FoldHelper::lift(node.bounds, |it| f.fold_type_param_bound(it)),
-        semi_token: Token ! [ ; ](tokens_helper(f, &node.semi_token.spans)),
+        semi_token: Token ! [;](tokens_helper(f, &node.semi_token.spans)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_item_type<F>(f: &mut F, node: ItemType) -> ItemType
 where
     F: Fold + ?Sized,
 {
     ItemType {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         vis: f.fold_visibility(node.vis),
         type_token: Token![type](tokens_helper(f, &node.type_token.span)),
         ident: f.fold_ident(node.ident),
         generics: f.fold_generics(node.generics),
-        eq_token: Token ! [ = ](tokens_helper(f, &node.eq_token.spans)),
+        eq_token: Token ! [=](tokens_helper(f, &node.eq_token.spans)),
         ty: Box::new(f.fold_type(*node.ty)),
-        semi_token: Token ! [ ; ](tokens_helper(f, &node.semi_token.spans)),
+        semi_token: Token ! [;](tokens_helper(f, &node.semi_token.spans)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_item_union<F>(f: &mut F, node: ItemUnion) -> ItemUnion
 where
     F: Fold + ?Sized,
 {
     ItemUnion {
@@ -2148,29 +2129,29 @@ where
 pub fn fold_item_use<F>(f: &mut F, node: ItemUse) -> ItemUse
 where
     F: Fold + ?Sized,
 {
     ItemUse {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         vis: f.fold_visibility(node.vis),
         use_token: Token![use](tokens_helper(f, &node.use_token.span)),
-        leading_colon: (node.leading_colon).map(|it| Token ! [ :: ](tokens_helper(f, &it.spans))),
+        leading_colon: (node.leading_colon).map(|it| Token ! [::](tokens_helper(f, &it.spans))),
         tree: f.fold_use_tree(node.tree),
-        semi_token: Token ! [ ; ](tokens_helper(f, &node.semi_token.spans)),
+        semi_token: Token ! [;](tokens_helper(f, &node.semi_token.spans)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_label<F>(f: &mut F, node: Label) -> Label
 where
     F: Fold + ?Sized,
 {
     Label {
         name: f.fold_lifetime(node.name),
-        colon_token: Token ! [ : ](tokens_helper(f, &node.colon_token.spans)),
+        colon_token: Token ! [:](tokens_helper(f, &node.colon_token.spans)),
     }
 }
 pub fn fold_lifetime<F>(f: &mut F, node: Lifetime) -> Lifetime
 where
     F: Fold + ?Sized,
 {
     Lifetime {
         apostrophe: f.fold_span(node.apostrophe),
@@ -2180,97 +2161,89 @@ where
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_lifetime_def<F>(f: &mut F, node: LifetimeDef) -> LifetimeDef
 where
     F: Fold + ?Sized,
 {
     LifetimeDef {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         lifetime: f.fold_lifetime(node.lifetime),
-        colon_token: (node.colon_token).map(|it| Token ! [ : ](tokens_helper(f, &it.spans))),
+        colon_token: (node.colon_token).map(|it| Token ! [:](tokens_helper(f, &it.spans))),
         bounds: FoldHelper::lift(node.bounds, |it| f.fold_lifetime(it)),
     }
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_lit<F>(f: &mut F, node: Lit) -> Lit
 where
     F: Fold + ?Sized,
 {
     match node {
         Lit::Str(_binding_0) => Lit::Str(f.fold_lit_str(_binding_0)),
         Lit::ByteStr(_binding_0) => Lit::ByteStr(f.fold_lit_byte_str(_binding_0)),
         Lit::Byte(_binding_0) => Lit::Byte(f.fold_lit_byte(_binding_0)),
         Lit::Char(_binding_0) => Lit::Char(f.fold_lit_char(_binding_0)),
         Lit::Int(_binding_0) => Lit::Int(f.fold_lit_int(_binding_0)),
         Lit::Float(_binding_0) => Lit::Float(f.fold_lit_float(_binding_0)),
         Lit::Bool(_binding_0) => Lit::Bool(f.fold_lit_bool(_binding_0)),
         Lit::Verbatim(_binding_0) => Lit::Verbatim(_binding_0),
     }
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_lit_bool<F>(f: &mut F, node: LitBool) -> LitBool
 where
     F: Fold + ?Sized,
 {
     LitBool {
         value: node.value,
         span: f.fold_span(node.span),
     }
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_lit_byte<F>(f: &mut F, node: LitByte) -> LitByte
 where
     F: Fold + ?Sized,
 {
     let span = f.fold_span(node.span());
     let mut node = node;
     node.set_span(span);
     node
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_lit_byte_str<F>(f: &mut F, node: LitByteStr) -> LitByteStr
 where
     F: Fold + ?Sized,
 {
     let span = f.fold_span(node.span());
     let mut node = node;
     node.set_span(span);
     node
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_lit_char<F>(f: &mut F, node: LitChar) -> LitChar
 where
     F: Fold + ?Sized,
 {
     let span = f.fold_span(node.span());
     let mut node = node;
     node.set_span(span);
     node
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_lit_float<F>(f: &mut F, node: LitFloat) -> LitFloat
 where
     F: Fold + ?Sized,
 {
     let span = f.fold_span(node.span());
     let mut node = node;
     node.set_span(span);
     node
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_lit_int<F>(f: &mut F, node: LitInt) -> LitInt
 where
     F: Fold + ?Sized,
 {
     let span = f.fold_span(node.span());
     let mut node = node;
     node.set_span(span);
     node
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_lit_str<F>(f: &mut F, node: LitStr) -> LitStr
 where
     F: Fold + ?Sized,
 {
     let span = f.fold_span(node.span());
     let mut node = node;
     node.set_span(span);
     node
@@ -2281,21 +2254,21 @@ where
     F: Fold + ?Sized,
 {
     Local {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         let_token: Token![let](tokens_helper(f, &node.let_token.span)),
         pat: f.fold_pat(node.pat),
         init: (node.init).map(|it| {
             (
-                Token ! [ = ](tokens_helper(f, &(it).0.spans)),
+                Token ! [=](tokens_helper(f, &(it).0.spans)),
                 Box::new(f.fold_expr(*(it).1)),
             )
         }),
-        semi_token: Token ! [ ; ](tokens_helper(f, &node.semi_token.spans)),
+        semi_token: Token ! [;](tokens_helper(f, &node.semi_token.spans)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_macro<F>(f: &mut F, node: Macro) -> Macro
 where
     F: Fold + ?Sized,
 {
     Macro {
@@ -2356,30 +2329,30 @@ where
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_meta_name_value<F>(f: &mut F, node: MetaNameValue) -> MetaNameValue
 where
     F: Fold + ?Sized,
 {
     MetaNameValue {
         path: f.fold_path(node.path),
-        eq_token: Token ! [ = ](tokens_helper(f, &node.eq_token.spans)),
+        eq_token: Token ! [=](tokens_helper(f, &node.eq_token.spans)),
         lit: f.fold_lit(node.lit),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_method_turbofish<F>(f: &mut F, node: MethodTurbofish) -> MethodTurbofish
 where
     F: Fold + ?Sized,
 {
     MethodTurbofish {
-        colon2_token: Token ! [ :: ](tokens_helper(f, &node.colon2_token.spans)),
-        lt_token: Token ! [ < ](tokens_helper(f, &node.lt_token.spans)),
+        colon2_token: Token ! [::](tokens_helper(f, &node.colon2_token.spans)),
+        lt_token: Token ! [<](tokens_helper(f, &node.lt_token.spans)),
         args: FoldHelper::lift(node.args, |it| f.fold_generic_method_argument(it)),
-        gt_token: Token ! [ > ](tokens_helper(f, &node.gt_token.spans)),
+        gt_token: Token ! [>](tokens_helper(f, &node.gt_token.spans)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_nested_meta<F>(f: &mut F, node: NestedMeta) -> NestedMeta
 where
     F: Fold + ?Sized,
 {
     match node {
@@ -2444,17 +2417,17 @@ where
 {
     PatIdent {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         by_ref: (node.by_ref).map(|it| Token![ref](tokens_helper(f, &it.span))),
         mutability: (node.mutability).map(|it| Token![mut](tokens_helper(f, &it.span))),
         ident: f.fold_ident(node.ident),
         subpat: (node.subpat).map(|it| {
             (
-                Token ! [ @ ](tokens_helper(f, &(it).0.spans)),
+                Token ! [@](tokens_helper(f, &(it).0.spans)),
                 Box::new(f.fold_pat(*(it).1)),
             )
         }),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_pat_lit<F>(f: &mut F, node: PatLit) -> PatLit
 where
@@ -2477,17 +2450,17 @@ where
 }
 #[cfg(feature = "full")]
 pub fn fold_pat_or<F>(f: &mut F, node: PatOr) -> PatOr
 where
     F: Fold + ?Sized,
 {
     PatOr {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
-        leading_vert: (node.leading_vert).map(|it| Token ! [ | ](tokens_helper(f, &it.spans))),
+        leading_vert: (node.leading_vert).map(|it| Token ! [|](tokens_helper(f, &it.spans))),
         cases: FoldHelper::lift(node.cases, |it| f.fold_pat(it)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_pat_path<F>(f: &mut F, node: PatPath) -> PatPath
 where
     F: Fold + ?Sized,
 {
@@ -2511,17 +2484,17 @@ where
 }
 #[cfg(feature = "full")]
 pub fn fold_pat_reference<F>(f: &mut F, node: PatReference) -> PatReference
 where
     F: Fold + ?Sized,
 {
     PatReference {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
-        and_token: Token ! [ & ](tokens_helper(f, &node.and_token.spans)),
+        and_token: Token ! [&](tokens_helper(f, &node.and_token.spans)),
         mutability: (node.mutability).map(|it| Token![mut](tokens_helper(f, &it.span))),
         pat: Box::new(f.fold_pat(*node.pat)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_pat_rest<F>(f: &mut F, node: PatRest) -> PatRest
 where
     F: Fold + ?Sized,
@@ -2580,17 +2553,17 @@ where
 #[cfg(feature = "full")]
 pub fn fold_pat_type<F>(f: &mut F, node: PatType) -> PatType
 where
     F: Fold + ?Sized,
 {
     PatType {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         pat: Box::new(f.fold_pat(*node.pat)),
-        colon_token: Token ! [ : ](tokens_helper(f, &node.colon_token.spans)),
+        colon_token: Token ! [:](tokens_helper(f, &node.colon_token.spans)),
         ty: Box::new(f.fold_type(*node.ty)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_pat_wild<F>(f: &mut F, node: PatWild) -> PatWild
 where
     F: Fold + ?Sized,
 {
@@ -2600,17 +2573,17 @@ where
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_path<F>(f: &mut F, node: Path) -> Path
 where
     F: Fold + ?Sized,
 {
     Path {
-        leading_colon: (node.leading_colon).map(|it| Token ! [ :: ](tokens_helper(f, &it.spans))),
+        leading_colon: (node.leading_colon).map(|it| Token ! [::](tokens_helper(f, &it.spans))),
         segments: FoldHelper::lift(node.segments, |it| f.fold_path_segment(it)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_path_arguments<F>(f: &mut F, node: PathArguments) -> PathArguments
 where
     F: Fold + ?Sized,
 {
@@ -2636,96 +2609,96 @@ where
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_predicate_eq<F>(f: &mut F, node: PredicateEq) -> PredicateEq
 where
     F: Fold + ?Sized,
 {
     PredicateEq {
         lhs_ty: f.fold_type(node.lhs_ty),
-        eq_token: Token ! [ = ](tokens_helper(f, &node.eq_token.spans)),
+        eq_token: Token ! [=](tokens_helper(f, &node.eq_token.spans)),
         rhs_ty: f.fold_type(node.rhs_ty),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_predicate_lifetime<F>(f: &mut F, node: PredicateLifetime) -> PredicateLifetime
 where
     F: Fold + ?Sized,
 {
     PredicateLifetime {
         lifetime: f.fold_lifetime(node.lifetime),
-        colon_token: Token ! [ : ](tokens_helper(f, &node.colon_token.spans)),
+        colon_token: Token ! [:](tokens_helper(f, &node.colon_token.spans)),
         bounds: FoldHelper::lift(node.bounds, |it| f.fold_lifetime(it)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_predicate_type<F>(f: &mut F, node: PredicateType) -> PredicateType
 where
     F: Fold + ?Sized,
 {
     PredicateType {
         lifetimes: (node.lifetimes).map(|it| f.fold_bound_lifetimes(it)),
         bounded_ty: f.fold_type(node.bounded_ty),
-        colon_token: Token ! [ : ](tokens_helper(f, &node.colon_token.spans)),
+        colon_token: Token ! [:](tokens_helper(f, &node.colon_token.spans)),
         bounds: FoldHelper::lift(node.bounds, |it| f.fold_type_param_bound(it)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_qself<F>(f: &mut F, node: QSelf) -> QSelf
 where
     F: Fold + ?Sized,
 {
     QSelf {
-        lt_token: Token ! [ < ](tokens_helper(f, &node.lt_token.spans)),
+        lt_token: Token ! [<](tokens_helper(f, &node.lt_token.spans)),
         ty: Box::new(f.fold_type(*node.ty)),
         position: node.position,
         as_token: (node.as_token).map(|it| Token![as](tokens_helper(f, &it.span))),
-        gt_token: Token ! [ > ](tokens_helper(f, &node.gt_token.spans)),
+        gt_token: Token ! [>](tokens_helper(f, &node.gt_token.spans)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_range_limits<F>(f: &mut F, node: RangeLimits) -> RangeLimits
 where
     F: Fold + ?Sized,
 {
     match node {
         RangeLimits::HalfOpen(_binding_0) => {
             RangeLimits::HalfOpen(Token![..](tokens_helper(f, &_binding_0.spans)))
         }
         RangeLimits::Closed(_binding_0) => {
-            RangeLimits::Closed(Token ! [ ..= ](tokens_helper(f, &_binding_0.spans)))
+            RangeLimits::Closed(Token ! [..=](tokens_helper(f, &_binding_0.spans)))
         }
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_receiver<F>(f: &mut F, node: Receiver) -> Receiver
 where
     F: Fold + ?Sized,
 {
     Receiver {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         reference: (node.reference).map(|it| {
             (
-                Token ! [ & ](tokens_helper(f, &(it).0.spans)),
+                Token ! [&](tokens_helper(f, &(it).0.spans)),
                 ((it).1).map(|it| f.fold_lifetime(it)),
             )
         }),
         mutability: (node.mutability).map(|it| Token![mut](tokens_helper(f, &it.span))),
         self_token: Token![self](tokens_helper(f, &node.self_token.span)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_return_type<F>(f: &mut F, node: ReturnType) -> ReturnType
 where
     F: Fold + ?Sized,
 {
     match node {
         ReturnType::Default => ReturnType::Default,
         ReturnType::Type(_binding_0, _binding_1) => ReturnType::Type(
-            Token ! [ -> ](tokens_helper(f, &_binding_0.spans)),
+            Token ! [->](tokens_helper(f, &_binding_0.spans)),
             Box::new(f.fold_type(*_binding_1)),
         ),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_signature<F>(f: &mut F, node: Signature) -> Signature
 where
     F: Fold + ?Sized,
@@ -2756,17 +2729,17 @@ where
     F: Fold + ?Sized,
 {
     match node {
         Stmt::Local(_binding_0) => Stmt::Local(f.fold_local(_binding_0)),
         Stmt::Item(_binding_0) => Stmt::Item(f.fold_item(_binding_0)),
         Stmt::Expr(_binding_0) => Stmt::Expr(f.fold_expr(_binding_0)),
         Stmt::Semi(_binding_0, _binding_1) => Stmt::Semi(
             f.fold_expr(_binding_0),
-            Token ! [ ; ](tokens_helper(f, &_binding_1.spans)),
+            Token ! [;](tokens_helper(f, &_binding_1.spans)),
         ),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_trait_bound<F>(f: &mut F, node: TraitBound) -> TraitBound
 where
     F: Fold + ?Sized,
 {
@@ -2780,17 +2753,17 @@ where
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_trait_bound_modifier<F>(f: &mut F, node: TraitBoundModifier) -> TraitBoundModifier
 where
     F: Fold + ?Sized,
 {
     match node {
         TraitBoundModifier::None => TraitBoundModifier::None,
         TraitBoundModifier::Maybe(_binding_0) => {
-            TraitBoundModifier::Maybe(Token ! [ ? ](tokens_helper(f, &_binding_0.spans)))
+            TraitBoundModifier::Maybe(Token ! [?](tokens_helper(f, &_binding_0.spans)))
         }
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_trait_item<F>(f: &mut F, node: TraitItem) -> TraitItem
 where
     F: Fold + ?Sized,
 {
@@ -2807,69 +2780,69 @@ where
 pub fn fold_trait_item_const<F>(f: &mut F, node: TraitItemConst) -> TraitItemConst
 where
     F: Fold + ?Sized,
 {
     TraitItemConst {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         const_token: Token![const](tokens_helper(f, &node.const_token.span)),
         ident: f.fold_ident(node.ident),
-        colon_token: Token ! [ : ](tokens_helper(f, &node.colon_token.spans)),
+        colon_token: Token ! [:](tokens_helper(f, &node.colon_token.spans)),
         ty: f.fold_type(node.ty),
         default: (node.default).map(|it| {
             (
-                Token ! [ = ](tokens_helper(f, &(it).0.spans)),
+                Token ! [=](tokens_helper(f, &(it).0.spans)),
                 f.fold_expr((it).1),
             )
         }),
-        semi_token: Token ! [ ; ](tokens_helper(f, &node.semi_token.spans)),
+        semi_token: Token ! [;](tokens_helper(f, &node.semi_token.spans)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_trait_item_macro<F>(f: &mut F, node: TraitItemMacro) -> TraitItemMacro
 where
     F: Fold + ?Sized,
 {
     TraitItemMacro {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         mac: f.fold_macro(node.mac),
-        semi_token: (node.semi_token).map(|it| Token ! [ ; ](tokens_helper(f, &it.spans))),
+        semi_token: (node.semi_token).map(|it| Token ! [;](tokens_helper(f, &it.spans))),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_trait_item_method<F>(f: &mut F, node: TraitItemMethod) -> TraitItemMethod
 where
     F: Fold + ?Sized,
 {
     TraitItemMethod {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         sig: f.fold_signature(node.sig),
         default: (node.default).map(|it| f.fold_block(it)),
-        semi_token: (node.semi_token).map(|it| Token ! [ ; ](tokens_helper(f, &it.spans))),
+        semi_token: (node.semi_token).map(|it| Token ! [;](tokens_helper(f, &it.spans))),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_trait_item_type<F>(f: &mut F, node: TraitItemType) -> TraitItemType
 where
     F: Fold + ?Sized,
 {
     TraitItemType {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         type_token: Token![type](tokens_helper(f, &node.type_token.span)),
         ident: f.fold_ident(node.ident),
         generics: f.fold_generics(node.generics),
-        colon_token: (node.colon_token).map(|it| Token ! [ : ](tokens_helper(f, &it.spans))),
+        colon_token: (node.colon_token).map(|it| Token ! [:](tokens_helper(f, &it.spans))),
         bounds: FoldHelper::lift(node.bounds, |it| f.fold_type_param_bound(it)),
         default: (node.default).map(|it| {
             (
-                Token ! [ = ](tokens_helper(f, &(it).0.spans)),
+                Token ! [=](tokens_helper(f, &(it).0.spans)),
                 f.fold_type((it).1),
             )
         }),
-        semi_token: Token ! [ ; ](tokens_helper(f, &node.semi_token.spans)),
+        semi_token: Token ! [;](tokens_helper(f, &node.semi_token.spans)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_type<F>(f: &mut F, node: Type) -> Type
 where
     F: Fold + ?Sized,
 {
     match node {
@@ -2894,17 +2867,17 @@ where
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_type_array<F>(f: &mut F, node: TypeArray) -> TypeArray
 where
     F: Fold + ?Sized,
 {
     TypeArray {
         bracket_token: Bracket(tokens_helper(f, &node.bracket_token.span)),
         elem: Box::new(f.fold_type(*node.elem)),
-        semi_token: Token ! [ ; ](tokens_helper(f, &node.semi_token.spans)),
+        semi_token: Token ! [;](tokens_helper(f, &node.semi_token.spans)),
         len: f.fold_expr(node.len),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_type_bare_fn<F>(f: &mut F, node: TypeBareFn) -> TypeBareFn
 where
     F: Fold + ?Sized,
 {
@@ -2969,19 +2942,19 @@ where
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_type_param<F>(f: &mut F, node: TypeParam) -> TypeParam
 where
     F: Fold + ?Sized,
 {
     TypeParam {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         ident: f.fold_ident(node.ident),
-        colon_token: (node.colon_token).map(|it| Token ! [ : ](tokens_helper(f, &it.spans))),
+        colon_token: (node.colon_token).map(|it| Token ! [:](tokens_helper(f, &it.spans))),
         bounds: FoldHelper::lift(node.bounds, |it| f.fold_type_param_bound(it)),
-        eq_token: (node.eq_token).map(|it| Token ! [ = ](tokens_helper(f, &it.spans))),
+        eq_token: (node.eq_token).map(|it| Token ! [=](tokens_helper(f, &it.spans))),
         default: (node.default).map(|it| f.fold_type(it)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_type_param_bound<F>(f: &mut F, node: TypeParamBound) -> TypeParamBound
 where
     F: Fold + ?Sized,
 {
@@ -3013,29 +2986,29 @@ where
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_type_ptr<F>(f: &mut F, node: TypePtr) -> TypePtr
 where
     F: Fold + ?Sized,
 {
     TypePtr {
-        star_token: Token ! [ * ](tokens_helper(f, &node.star_token.spans)),
+        star_token: Token ! [*](tokens_helper(f, &node.star_token.spans)),
         const_token: (node.const_token).map(|it| Token![const](tokens_helper(f, &it.span))),
         mutability: (node.mutability).map(|it| Token![mut](tokens_helper(f, &it.span))),
         elem: Box::new(f.fold_type(*node.elem)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_type_reference<F>(f: &mut F, node: TypeReference) -> TypeReference
 where
     F: Fold + ?Sized,
 {
     TypeReference {
-        and_token: Token ! [ & ](tokens_helper(f, &node.and_token.spans)),
+        and_token: Token ! [&](tokens_helper(f, &node.and_token.spans)),
         lifetime: (node.lifetime).map(|it| f.fold_lifetime(it)),
         mutability: (node.mutability).map(|it| Token![mut](tokens_helper(f, &it.span))),
         elem: Box::new(f.fold_type(*node.elem)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_type_slice<F>(f: &mut F, node: TypeSlice) -> TypeSlice
 where
@@ -3067,28 +3040,28 @@ where
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_un_op<F>(f: &mut F, node: UnOp) -> UnOp
 where
     F: Fold + ?Sized,
 {
     match node {
-        UnOp::Deref(_binding_0) => UnOp::Deref(Token ! [ * ](tokens_helper(f, &_binding_0.spans))),
+        UnOp::Deref(_binding_0) => UnOp::Deref(Token ! [*](tokens_helper(f, &_binding_0.spans))),
         UnOp::Not(_binding_0) => UnOp::Not(Token![!](tokens_helper(f, &_binding_0.spans))),
-        UnOp::Neg(_binding_0) => UnOp::Neg(Token ! [ - ](tokens_helper(f, &_binding_0.spans))),
+        UnOp::Neg(_binding_0) => UnOp::Neg(Token ! [-](tokens_helper(f, &_binding_0.spans))),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_use_glob<F>(f: &mut F, node: UseGlob) -> UseGlob
 where
     F: Fold + ?Sized,
 {
     UseGlob {
-        star_token: Token ! [ * ](tokens_helper(f, &node.star_token.spans)),
+        star_token: Token ! [*](tokens_helper(f, &node.star_token.spans)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_use_group<F>(f: &mut F, node: UseGroup) -> UseGroup
 where
     F: Fold + ?Sized,
 {
     UseGroup {
@@ -3107,17 +3080,17 @@ where
 }
 #[cfg(feature = "full")]
 pub fn fold_use_path<F>(f: &mut F, node: UsePath) -> UsePath
 where
     F: Fold + ?Sized,
 {
     UsePath {
         ident: f.fold_ident(node.ident),
-        colon2_token: Token ! [ :: ](tokens_helper(f, &node.colon2_token.spans)),
+        colon2_token: Token ! [::](tokens_helper(f, &node.colon2_token.spans)),
         tree: Box::new(f.fold_use_tree(*node.tree)),
     }
 }
 #[cfg(feature = "full")]
 pub fn fold_use_rename<F>(f: &mut F, node: UseRename) -> UseRename
 where
     F: Fold + ?Sized,
 {
@@ -3142,31 +3115,31 @@ where
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_variadic<F>(f: &mut F, node: Variadic) -> Variadic
 where
     F: Fold + ?Sized,
 {
     Variadic {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
-        dots: Token ! [ ... ](tokens_helper(f, &node.dots.spans)),
+        dots: Token ! [...](tokens_helper(f, &node.dots.spans)),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_variant<F>(f: &mut F, node: Variant) -> Variant
 where
     F: Fold + ?Sized,
 {
     Variant {
         attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
         ident: f.fold_ident(node.ident),
         fields: f.fold_fields(node.fields),
         discriminant: (node.discriminant).map(|it| {
             (
-                Token ! [ = ](tokens_helper(f, &(it).0.spans)),
+                Token ! [=](tokens_helper(f, &(it).0.spans)),
                 f.fold_expr((it).1),
             )
         }),
     }
 }
 #[cfg(any(feature = "derive", feature = "full"))]
 pub fn fold_vis_crate<F>(f: &mut F, node: VisCrate) -> VisCrate
 where
diff --git a/third_party/rust/syn/src/gen/hash.rs b/third_party/rust/syn/src/gen/hash.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/src/gen/hash.rs
@@ -0,0 +1,2691 @@
+// This file is @generated by syn-internal-codegen.
+// It is not intended for manual editing.
+
+#[cfg(any(feature = "derive", feature = "full"))]
+use crate::tt::TokenStreamHelper;
+use crate::*;
+use std::hash::{Hash, Hasher};
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for Abi {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.name.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for AngleBracketedGenericArguments {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.colon2_token.hash(state);
+        self.args.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for Arm {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.pat.hash(state);
+        self.guard.hash(state);
+        self.body.hash(state);
+        self.comma.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for AttrStyle {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            AttrStyle::Outer => {
+                state.write_u8(0u8);
+            }
+            AttrStyle::Inner(_) => {
+                state.write_u8(1u8);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for Attribute {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.style.hash(state);
+        self.path.hash(state);
+        TokenStreamHelper(&self.tokens).hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for BareFnArg {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.name.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for BinOp {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            BinOp::Add(_) => {
+                state.write_u8(0u8);
+            }
+            BinOp::Sub(_) => {
+                state.write_u8(1u8);
+            }
+            BinOp::Mul(_) => {
+                state.write_u8(2u8);
+            }
+            BinOp::Div(_) => {
+                state.write_u8(3u8);
+            }
+            BinOp::Rem(_) => {
+                state.write_u8(4u8);
+            }
+            BinOp::And(_) => {
+                state.write_u8(5u8);
+            }
+            BinOp::Or(_) => {
+                state.write_u8(6u8);
+            }
+            BinOp::BitXor(_) => {
+                state.write_u8(7u8);
+            }
+            BinOp::BitAnd(_) => {
+                state.write_u8(8u8);
+            }
+            BinOp::BitOr(_) => {
+                state.write_u8(9u8);
+            }
+            BinOp::Shl(_) => {
+                state.write_u8(10u8);
+            }
+            BinOp::Shr(_) => {
+                state.write_u8(11u8);
+            }
+            BinOp::Eq(_) => {
+                state.write_u8(12u8);
+            }
+            BinOp::Lt(_) => {
+                state.write_u8(13u8);
+            }
+            BinOp::Le(_) => {
+                state.write_u8(14u8);
+            }
+            BinOp::Ne(_) => {
+                state.write_u8(15u8);
+            }
+            BinOp::Ge(_) => {
+                state.write_u8(16u8);
+            }
+            BinOp::Gt(_) => {
+                state.write_u8(17u8);
+            }
+            BinOp::AddEq(_) => {
+                state.write_u8(18u8);
+            }
+            BinOp::SubEq(_) => {
+                state.write_u8(19u8);
+            }
+            BinOp::MulEq(_) => {
+                state.write_u8(20u8);
+            }
+            BinOp::DivEq(_) => {
+                state.write_u8(21u8);
+            }
+            BinOp::RemEq(_) => {
+                state.write_u8(22u8);
+            }
+            BinOp::BitXorEq(_) => {
+                state.write_u8(23u8);
+            }
+            BinOp::BitAndEq(_) => {
+                state.write_u8(24u8);
+            }
+            BinOp::BitOrEq(_) => {
+                state.write_u8(25u8);
+            }
+            BinOp::ShlEq(_) => {
+                state.write_u8(26u8);
+            }
+            BinOp::ShrEq(_) => {
+                state.write_u8(27u8);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for Binding {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.ident.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for Block {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.stmts.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for BoundLifetimes {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.lifetimes.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for ConstParam {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.ident.hash(state);
+        self.ty.hash(state);
+        self.eq_token.hash(state);
+        self.default.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for Constraint {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.ident.hash(state);
+        self.bounds.hash(state);
+    }
+}
+#[cfg(feature = "derive")]
+impl Hash for Data {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            Data::Struct(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            Data::Enum(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            Data::Union(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(feature = "derive")]
+impl Hash for DataEnum {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.variants.hash(state);
+    }
+}
+#[cfg(feature = "derive")]
+impl Hash for DataStruct {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.fields.hash(state);
+        self.semi_token.hash(state);
+    }
+}
+#[cfg(feature = "derive")]
+impl Hash for DataUnion {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.fields.hash(state);
+    }
+}
+#[cfg(feature = "derive")]
+impl Hash for DeriveInput {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.data.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for Expr {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            #[cfg(feature = "full")]
+            Expr::Array(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Assign(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::AssignOp(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Async(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Await(v0) => {
+                state.write_u8(4u8);
+                v0.hash(state);
+            }
+            Expr::Binary(v0) => {
+                state.write_u8(5u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Block(v0) => {
+                state.write_u8(6u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Box(v0) => {
+                state.write_u8(7u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Break(v0) => {
+                state.write_u8(8u8);
+                v0.hash(state);
+            }
+            Expr::Call(v0) => {
+                state.write_u8(9u8);
+                v0.hash(state);
+            }
+            Expr::Cast(v0) => {
+                state.write_u8(10u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Closure(v0) => {
+                state.write_u8(11u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Continue(v0) => {
+                state.write_u8(12u8);
+                v0.hash(state);
+            }
+            Expr::Field(v0) => {
+                state.write_u8(13u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::ForLoop(v0) => {
+                state.write_u8(14u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Group(v0) => {
+                state.write_u8(15u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::If(v0) => {
+                state.write_u8(16u8);
+                v0.hash(state);
+            }
+            Expr::Index(v0) => {
+                state.write_u8(17u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Let(v0) => {
+                state.write_u8(18u8);
+                v0.hash(state);
+            }
+            Expr::Lit(v0) => {
+                state.write_u8(19u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Loop(v0) => {
+                state.write_u8(20u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Macro(v0) => {
+                state.write_u8(21u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Match(v0) => {
+                state.write_u8(22u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::MethodCall(v0) => {
+                state.write_u8(23u8);
+                v0.hash(state);
+            }
+            Expr::Paren(v0) => {
+                state.write_u8(24u8);
+                v0.hash(state);
+            }
+            Expr::Path(v0) => {
+                state.write_u8(25u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Range(v0) => {
+                state.write_u8(26u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Reference(v0) => {
+                state.write_u8(27u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Repeat(v0) => {
+                state.write_u8(28u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Return(v0) => {
+                state.write_u8(29u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Struct(v0) => {
+                state.write_u8(30u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Try(v0) => {
+                state.write_u8(31u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::TryBlock(v0) => {
+                state.write_u8(32u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Tuple(v0) => {
+                state.write_u8(33u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Type(v0) => {
+                state.write_u8(34u8);
+                v0.hash(state);
+            }
+            Expr::Unary(v0) => {
+                state.write_u8(35u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Unsafe(v0) => {
+                state.write_u8(36u8);
+                v0.hash(state);
+            }
+            Expr::Verbatim(v0) => {
+                state.write_u8(37u8);
+                TokenStreamHelper(v0).hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::While(v0) => {
+                state.write_u8(38u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            Expr::Yield(v0) => {
+                state.write_u8(39u8);
+                v0.hash(state);
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprArray {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.elems.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprAssign {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.left.hash(state);
+        self.right.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprAssignOp {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.left.hash(state);
+        self.op.hash(state);
+        self.right.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprAsync {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.capture.hash(state);
+        self.block.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprAwait {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.base.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for ExprBinary {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.left.hash(state);
+        self.op.hash(state);
+        self.right.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprBlock {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.label.hash(state);
+        self.block.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprBox {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprBreak {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.label.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for ExprCall {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.func.hash(state);
+        self.args.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for ExprCast {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprClosure {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.asyncness.hash(state);
+        self.movability.hash(state);
+        self.capture.hash(state);
+        self.inputs.hash(state);
+        self.output.hash(state);
+        self.body.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprContinue {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.label.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for ExprField {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.base.hash(state);
+        self.member.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprForLoop {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.label.hash(state);
+        self.pat.hash(state);
+        self.expr.hash(state);
+        self.body.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprGroup {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprIf {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.cond.hash(state);
+        self.then_branch.hash(state);
+        self.else_branch.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for ExprIndex {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+        self.index.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprLet {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.pat.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for ExprLit {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.lit.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprLoop {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.label.hash(state);
+        self.body.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprMacro {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.mac.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprMatch {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+        self.arms.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprMethodCall {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.receiver.hash(state);
+        self.method.hash(state);
+        self.turbofish.hash(state);
+        self.args.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for ExprParen {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for ExprPath {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.qself.hash(state);
+        self.path.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprRange {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.from.hash(state);
+        self.limits.hash(state);
+        self.to.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprReference {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.mutability.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprRepeat {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+        self.len.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprReturn {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprStruct {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.path.hash(state);
+        self.fields.hash(state);
+        self.dot2_token.hash(state);
+        self.rest.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprTry {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprTryBlock {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.block.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprTuple {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.elems.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprType {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for ExprUnary {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.op.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprUnsafe {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.block.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprWhile {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.label.hash(state);
+        self.cond.hash(state);
+        self.body.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ExprYield {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for Field {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.colon_token.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for FieldPat {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.member.hash(state);
+        self.colon_token.hash(state);
+        self.pat.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for FieldValue {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.member.hash(state);
+        self.colon_token.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for Fields {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            Fields::Named(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            Fields::Unnamed(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            Fields::Unit => {
+                state.write_u8(2u8);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for FieldsNamed {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.named.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for FieldsUnnamed {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.unnamed.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for File {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.shebang.hash(state);
+        self.attrs.hash(state);
+        self.items.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for FnArg {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            FnArg::Receiver(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            FnArg::Typed(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ForeignItem {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            ForeignItem::Fn(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            ForeignItem::Static(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            ForeignItem::Type(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            ForeignItem::Macro(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            ForeignItem::Verbatim(v0) => {
+                state.write_u8(4u8);
+                TokenStreamHelper(v0).hash(state);
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ForeignItemFn {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.sig.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ForeignItemMacro {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.mac.hash(state);
+        self.semi_token.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ForeignItemStatic {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.mutability.hash(state);
+        self.ident.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ForeignItemType {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for GenericArgument {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            GenericArgument::Lifetime(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            GenericArgument::Type(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            GenericArgument::Binding(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            GenericArgument::Constraint(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            GenericArgument::Const(v0) => {
+                state.write_u8(4u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for GenericMethodArgument {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            GenericMethodArgument::Type(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            GenericMethodArgument::Const(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for GenericParam {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            GenericParam::Type(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            GenericParam::Lifetime(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            GenericParam::Const(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for Generics {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.lt_token.hash(state);
+        self.params.hash(state);
+        self.gt_token.hash(state);
+        self.where_clause.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ImplItem {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            ImplItem::Const(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            ImplItem::Method(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            ImplItem::Type(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            ImplItem::Macro(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            ImplItem::Verbatim(v0) => {
+                state.write_u8(4u8);
+                TokenStreamHelper(v0).hash(state);
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ImplItemConst {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.defaultness.hash(state);
+        self.ident.hash(state);
+        self.ty.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ImplItemMacro {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.mac.hash(state);
+        self.semi_token.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ImplItemMethod {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.defaultness.hash(state);
+        self.sig.hash(state);
+        self.block.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ImplItemType {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.defaultness.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for Item {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            Item::Const(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            Item::Enum(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            Item::ExternCrate(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            Item::Fn(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            Item::ForeignMod(v0) => {
+                state.write_u8(4u8);
+                v0.hash(state);
+            }
+            Item::Impl(v0) => {
+                state.write_u8(5u8);
+                v0.hash(state);
+            }
+            Item::Macro(v0) => {
+                state.write_u8(6u8);
+                v0.hash(state);
+            }
+            Item::Macro2(v0) => {
+                state.write_u8(7u8);
+                v0.hash(state);
+            }
+            Item::Mod(v0) => {
+                state.write_u8(8u8);
+                v0.hash(state);
+            }
+            Item::Static(v0) => {
+                state.write_u8(9u8);
+                v0.hash(state);
+            }
+            Item::Struct(v0) => {
+                state.write_u8(10u8);
+                v0.hash(state);
+            }
+            Item::Trait(v0) => {
+                state.write_u8(11u8);
+                v0.hash(state);
+            }
+            Item::TraitAlias(v0) => {
+                state.write_u8(12u8);
+                v0.hash(state);
+            }
+            Item::Type(v0) => {
+                state.write_u8(13u8);
+                v0.hash(state);
+            }
+            Item::Union(v0) => {
+                state.write_u8(14u8);
+                v0.hash(state);
+            }
+            Item::Use(v0) => {
+                state.write_u8(15u8);
+                v0.hash(state);
+            }
+            Item::Verbatim(v0) => {
+                state.write_u8(16u8);
+                TokenStreamHelper(v0).hash(state);
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ItemConst {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.ty.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ItemEnum {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.variants.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ItemExternCrate {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.rename.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ItemFn {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.sig.hash(state);
+        self.block.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ItemForeignMod {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.abi.hash(state);
+        self.items.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ItemImpl {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.defaultness.hash(state);
+        self.unsafety.hash(state);
+        self.generics.hash(state);
+        self.trait_.hash(state);
+        self.self_ty.hash(state);
+        self.items.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ItemMacro {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.ident.hash(state);
+        self.mac.hash(state);
+        self.semi_token.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ItemMacro2 {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        TokenStreamHelper(&self.rules).hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ItemMod {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.content.hash(state);
+        self.semi.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ItemStatic {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.mutability.hash(state);
+        self.ident.hash(state);
+        self.ty.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ItemStruct {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.fields.hash(state);
+        self.semi_token.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ItemTrait {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.unsafety.hash(state);
+        self.auto_token.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.colon_token.hash(state);
+        self.supertraits.hash(state);
+        self.items.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ItemTraitAlias {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.bounds.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ItemType {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ItemUnion {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.fields.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for ItemUse {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.leading_colon.hash(state);
+        self.tree.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for Label {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.name.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for LifetimeDef {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.lifetime.hash(state);
+        self.colon_token.hash(state);
+        self.bounds.hash(state);
+    }
+}
+impl Hash for Lit {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            Lit::Str(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            Lit::ByteStr(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            Lit::Byte(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            Lit::Char(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            Lit::Int(v0) => {
+                state.write_u8(4u8);
+                v0.hash(state);
+            }
+            Lit::Float(v0) => {
+                state.write_u8(5u8);
+                v0.hash(state);
+            }
+            Lit::Bool(v0) => {
+                state.write_u8(6u8);
+                v0.hash(state);
+            }
+            Lit::Verbatim(v0) => {
+                state.write_u8(7u8);
+                v0.to_string().hash(state);
+            }
+        }
+    }
+}
+impl Hash for LitBool {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.value.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for Local {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.pat.hash(state);
+        self.init.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for Macro {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.path.hash(state);
+        self.delimiter.hash(state);
+        TokenStreamHelper(&self.tokens).hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for MacroDelimiter {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            MacroDelimiter::Paren(_) => {
+                state.write_u8(0u8);
+            }
+            MacroDelimiter::Brace(_) => {
+                state.write_u8(1u8);
+            }
+            MacroDelimiter::Bracket(_) => {
+                state.write_u8(2u8);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for Meta {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            Meta::Path(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            Meta::List(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            Meta::NameValue(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for MetaList {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.path.hash(state);
+        self.nested.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for MetaNameValue {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.path.hash(state);
+        self.lit.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for MethodTurbofish {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.args.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for NestedMeta {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            NestedMeta::Meta(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            NestedMeta::Lit(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for ParenthesizedGenericArguments {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.inputs.hash(state);
+        self.output.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for Pat {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            Pat::Box(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            Pat::Ident(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            Pat::Lit(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            Pat::Macro(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            Pat::Or(v0) => {
+                state.write_u8(4u8);
+                v0.hash(state);
+            }
+            Pat::Path(v0) => {
+                state.write_u8(5u8);
+                v0.hash(state);
+            }
+            Pat::Range(v0) => {
+                state.write_u8(6u8);
+                v0.hash(state);
+            }
+            Pat::Reference(v0) => {
+                state.write_u8(7u8);
+                v0.hash(state);
+            }
+            Pat::Rest(v0) => {
+                state.write_u8(8u8);
+                v0.hash(state);
+            }
+            Pat::Slice(v0) => {
+                state.write_u8(9u8);
+                v0.hash(state);
+            }
+            Pat::Struct(v0) => {
+                state.write_u8(10u8);
+                v0.hash(state);
+            }
+            Pat::Tuple(v0) => {
+                state.write_u8(11u8);
+                v0.hash(state);
+            }
+            Pat::TupleStruct(v0) => {
+                state.write_u8(12u8);
+                v0.hash(state);
+            }
+            Pat::Type(v0) => {
+                state.write_u8(13u8);
+                v0.hash(state);
+            }
+            Pat::Verbatim(v0) => {
+                state.write_u8(14u8);
+                TokenStreamHelper(v0).hash(state);
+            }
+            Pat::Wild(v0) => {
+                state.write_u8(15u8);
+                v0.hash(state);
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for PatBox {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.pat.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for PatIdent {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.by_ref.hash(state);
+        self.mutability.hash(state);
+        self.ident.hash(state);
+        self.subpat.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for PatLit {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for PatMacro {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.mac.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for PatOr {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.leading_vert.hash(state);
+        self.cases.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for PatPath {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.qself.hash(state);
+        self.path.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for PatRange {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.lo.hash(state);
+        self.limits.hash(state);
+        self.hi.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for PatReference {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.mutability.hash(state);
+        self.pat.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for PatRest {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for PatSlice {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.elems.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for PatStruct {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.path.hash(state);
+        self.fields.hash(state);
+        self.dot2_token.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for PatTuple {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.elems.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for PatTupleStruct {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.path.hash(state);
+        self.pat.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for PatType {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.pat.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for PatWild {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for Path {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.leading_colon.hash(state);
+        self.segments.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for PathArguments {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            PathArguments::None => {
+                state.write_u8(0u8);
+            }
+            PathArguments::AngleBracketed(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            PathArguments::Parenthesized(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for PathSegment {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.ident.hash(state);
+        self.arguments.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for PredicateEq {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.lhs_ty.hash(state);
+        self.rhs_ty.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for PredicateLifetime {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.lifetime.hash(state);
+        self.bounds.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for PredicateType {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.lifetimes.hash(state);
+        self.bounded_ty.hash(state);
+        self.bounds.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for QSelf {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.ty.hash(state);
+        self.position.hash(state);
+        self.as_token.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for RangeLimits {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            RangeLimits::HalfOpen(_) => {
+                state.write_u8(0u8);
+            }
+            RangeLimits::Closed(_) => {
+                state.write_u8(1u8);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for Receiver {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.reference.hash(state);
+        self.mutability.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for ReturnType {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            ReturnType::Default => {
+                state.write_u8(0u8);
+            }
+            ReturnType::Type(_, v1) => {
+                state.write_u8(1u8);
+                v1.hash(state);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for Signature {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.constness.hash(state);
+        self.asyncness.hash(state);
+        self.unsafety.hash(state);
+        self.abi.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.inputs.hash(state);
+        self.variadic.hash(state);
+        self.output.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for Stmt {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            Stmt::Local(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            Stmt::Item(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            Stmt::Expr(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            Stmt::Semi(v0, _) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TraitBound {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.paren_token.hash(state);
+        self.modifier.hash(state);
+        self.lifetimes.hash(state);
+        self.path.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TraitBoundModifier {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            TraitBoundModifier::None => {
+                state.write_u8(0u8);
+            }
+            TraitBoundModifier::Maybe(_) => {
+                state.write_u8(1u8);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for TraitItem {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            TraitItem::Const(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            TraitItem::Method(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            TraitItem::Type(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            TraitItem::Macro(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            TraitItem::Verbatim(v0) => {
+                state.write_u8(4u8);
+                TokenStreamHelper(v0).hash(state);
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for TraitItemConst {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.ident.hash(state);
+        self.ty.hash(state);
+        self.default.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for TraitItemMacro {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.mac.hash(state);
+        self.semi_token.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for TraitItemMethod {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.sig.hash(state);
+        self.default.hash(state);
+        self.semi_token.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for TraitItemType {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.colon_token.hash(state);
+        self.bounds.hash(state);
+        self.default.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for Type {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            Type::Array(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            Type::BareFn(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            Type::Group(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            Type::ImplTrait(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            Type::Infer(v0) => {
+                state.write_u8(4u8);
+                v0.hash(state);
+            }
+            Type::Macro(v0) => {
+                state.write_u8(5u8);
+                v0.hash(state);
+            }
+            Type::Never(v0) => {
+                state.write_u8(6u8);
+                v0.hash(state);
+            }
+            Type::Paren(v0) => {
+                state.write_u8(7u8);
+                v0.hash(state);
+            }
+            Type::Path(v0) => {
+                state.write_u8(8u8);
+                v0.hash(state);
+            }
+            Type::Ptr(v0) => {
+                state.write_u8(9u8);
+                v0.hash(state);
+            }
+            Type::Reference(v0) => {
+                state.write_u8(10u8);
+                v0.hash(state);
+            }
+            Type::Slice(v0) => {
+                state.write_u8(11u8);
+                v0.hash(state);
+            }
+            Type::TraitObject(v0) => {
+                state.write_u8(12u8);
+                v0.hash(state);
+            }
+            Type::Tuple(v0) => {
+                state.write_u8(13u8);
+                v0.hash(state);
+            }
+            Type::Verbatim(v0) => {
+                state.write_u8(14u8);
+                TokenStreamHelper(v0).hash(state);
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TypeArray {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.elem.hash(state);
+        self.len.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TypeBareFn {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.lifetimes.hash(state);
+        self.unsafety.hash(state);
+        self.abi.hash(state);
+        self.inputs.hash(state);
+        self.variadic.hash(state);
+        self.output.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TypeGroup {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.elem.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TypeImplTrait {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.bounds.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TypeInfer {
+    fn hash<H>(&self, _state: &mut H)
+    where
+        H: Hasher,
+    {
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TypeMacro {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.mac.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TypeNever {
+    fn hash<H>(&self, _state: &mut H)
+    where
+        H: Hasher,
+    {
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TypeParam {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.ident.hash(state);
+        self.colon_token.hash(state);
+        self.bounds.hash(state);
+        self.eq_token.hash(state);
+        self.default.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TypeParamBound {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            TypeParamBound::Trait(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            TypeParamBound::Lifetime(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TypeParen {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.elem.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TypePath {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.qself.hash(state);
+        self.path.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TypePtr {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.const_token.hash(state);
+        self.mutability.hash(state);
+        self.elem.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TypeReference {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.lifetime.hash(state);
+        self.mutability.hash(state);
+        self.elem.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TypeSlice {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.elem.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TypeTraitObject {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.dyn_token.hash(state);
+        self.bounds.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for TypeTuple {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.elems.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for UnOp {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            UnOp::Deref(_) => {
+                state.write_u8(0u8);
+            }
+            UnOp::Not(_) => {
+                state.write_u8(1u8);
+            }
+            UnOp::Neg(_) => {
+                state.write_u8(2u8);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for UseGlob {
+    fn hash<H>(&self, _state: &mut H)
+    where
+        H: Hasher,
+    {
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for UseGroup {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.items.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for UseName {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.ident.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for UsePath {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.ident.hash(state);
+        self.tree.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for UseRename {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.ident.hash(state);
+        self.rename.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+impl Hash for UseTree {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            UseTree::Path(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            UseTree::Name(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            UseTree::Rename(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            UseTree::Glob(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            UseTree::Group(v0) => {
+                state.write_u8(4u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for Variadic {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for Variant {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.ident.hash(state);
+        self.fields.hash(state);
+        self.discriminant.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for VisCrate {
+    fn hash<H>(&self, _state: &mut H)
+    where
+        H: Hasher,
+    {
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for VisPublic {
+    fn hash<H>(&self, _state: &mut H)
+    where
+        H: Hasher,
+    {
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for VisRestricted {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.in_token.hash(state);
+        self.path.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for Visibility {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            Visibility::Public(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            Visibility::Crate(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            Visibility::Restricted(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            Visibility::Inherited => {
+                state.write_u8(3u8);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for WhereClause {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.predicates.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl Hash for WherePredicate {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            WherePredicate::Type(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            WherePredicate::Lifetime(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            WherePredicate::Eq(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
diff --git a/third_party/rust/syn/src/gen/visit.rs b/third_party/rust/syn/src/gen/visit.rs
--- a/third_party/rust/syn/src/gen/visit.rs
+++ b/third_party/rust/syn/src/gen/visit.rs
@@ -15,27 +15,26 @@ macro_rules! full {
     };
 }
 #[cfg(all(feature = "derive", not(feature = "full")))]
 macro_rules! full {
     ($e:expr) => {
         unreachable!()
     };
 }
-#[cfg(any(feature = "full", feature = "derive"))]
 macro_rules! skip {
     ($($tt:tt)*) => {};
 }
 /// Syntax tree traversal to walk a shared borrow of a syntax tree.
 ///
 /// See the [module documentation] for details.
 ///
 /// [module documentation]: self
 ///
-/// *This trait is available if Syn is built with the `"visit"` feature.*
+/// *This trait is available only if Syn is built with the `"visit"` feature.*
 pub trait Visit<'ast> {
     #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_abi(&mut self, i: &'ast Abi) {
         visit_abi(self, i)
     }
     #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_angle_bracketed_generic_arguments(&mut self, i: &'ast AngleBracketedGenericArguments) {
         visit_angle_bracketed_generic_arguments(self, i)
@@ -429,45 +428,37 @@ pub trait Visit<'ast> {
     }
     fn visit_lifetime(&mut self, i: &'ast Lifetime) {
         visit_lifetime(self, i)
     }
     #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lifetime_def(&mut self, i: &'ast LifetimeDef) {
         visit_lifetime_def(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lit(&mut self, i: &'ast Lit) {
         visit_lit(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lit_bool(&mut self, i: &'ast LitBool) {
         visit_lit_bool(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lit_byte(&mut self, i: &'ast LitByte) {
         visit_lit_byte(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lit_byte_str(&mut self, i: &'ast LitByteStr) {
         visit_lit_byte_str(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lit_char(&mut self, i: &'ast LitChar) {
         visit_lit_char(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lit_float(&mut self, i: &'ast LitFloat) {
         visit_lit_float(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lit_int(&mut self, i: &'ast LitInt) {
         visit_lit_int(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lit_str(&mut self, i: &'ast LitStr) {
         visit_lit_str(self, i)
     }
     #[cfg(feature = "full")]
     fn visit_local(&mut self, i: &'ast Local) {
         visit_local(self, i)
     }
     #[cfg(any(feature = "derive", feature = "full"))]
@@ -2532,17 +2523,16 @@ where
     for el in Punctuated::pairs(&node.bounds) {
         let (it, p) = el.into_tuple();
         v.visit_lifetime(it);
         if let Some(p) = p {
             tokens_helper(v, &p.spans);
         }
     }
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn visit_lit<'ast, V>(v: &mut V, node: &'ast Lit)
 where
     V: Visit<'ast> + ?Sized,
 {
     match node {
         Lit::Str(_binding_0) => {
             v.visit_lit_str(_binding_0);
         }
@@ -2564,55 +2554,48 @@ where
         Lit::Bool(_binding_0) => {
             v.visit_lit_bool(_binding_0);
         }
         Lit::Verbatim(_binding_0) => {
             skip!(_binding_0);
         }
     }
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn visit_lit_bool<'ast, V>(v: &mut V, node: &'ast LitBool)
 where
     V: Visit<'ast> + ?Sized,
 {
     skip!(node.value);
     v.visit_span(&node.span);
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn visit_lit_byte<'ast, V>(v: &mut V, node: &'ast LitByte)
 where
     V: Visit<'ast> + ?Sized,
 {
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn visit_lit_byte_str<'ast, V>(v: &mut V, node: &'ast LitByteStr)
 where
     V: Visit<'ast> + ?Sized,
 {
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn visit_lit_char<'ast, V>(v: &mut V, node: &'ast LitChar)
 where
     V: Visit<'ast> + ?Sized,
 {
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn visit_lit_float<'ast, V>(v: &mut V, node: &'ast LitFloat)
 where
     V: Visit<'ast> + ?Sized,
 {
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn visit_lit_int<'ast, V>(v: &mut V, node: &'ast LitInt)
 where
     V: Visit<'ast> + ?Sized,
 {
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn visit_lit_str<'ast, V>(v: &mut V, node: &'ast LitStr)
 where
     V: Visit<'ast> + ?Sized,
 {
 }
 #[cfg(feature = "full")]
 pub fn visit_local<'ast, V>(v: &mut V, node: &'ast Local)
 where
diff --git a/third_party/rust/syn/src/gen/visit_mut.rs b/third_party/rust/syn/src/gen/visit_mut.rs
--- a/third_party/rust/syn/src/gen/visit_mut.rs
+++ b/third_party/rust/syn/src/gen/visit_mut.rs
@@ -15,28 +15,27 @@ macro_rules! full {
     };
 }
 #[cfg(all(feature = "derive", not(feature = "full")))]
 macro_rules! full {
     ($e:expr) => {
         unreachable!()
     };
 }
-#[cfg(any(feature = "full", feature = "derive"))]
 macro_rules! skip {
     ($($tt:tt)*) => {};
 }
 /// Syntax tree traversal to mutate an exclusive borrow of a syntax tree in
 /// place.
 ///
 /// See the [module documentation] for details.
 ///
 /// [module documentation]: self
 ///
-/// *This trait is available if Syn is built with the `"visit-mut"` feature.*
+/// *This trait is available only if Syn is built with the `"visit-mut"` feature.*
 pub trait VisitMut {
     #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_abi_mut(&mut self, i: &mut Abi) {
         visit_abi_mut(self, i)
     }
     #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_angle_bracketed_generic_arguments_mut(
         &mut self,
@@ -433,45 +432,37 @@ pub trait VisitMut {
     }
     fn visit_lifetime_mut(&mut self, i: &mut Lifetime) {
         visit_lifetime_mut(self, i)
     }
     #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lifetime_def_mut(&mut self, i: &mut LifetimeDef) {
         visit_lifetime_def_mut(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lit_mut(&mut self, i: &mut Lit) {
         visit_lit_mut(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lit_bool_mut(&mut self, i: &mut LitBool) {
         visit_lit_bool_mut(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lit_byte_mut(&mut self, i: &mut LitByte) {
         visit_lit_byte_mut(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lit_byte_str_mut(&mut self, i: &mut LitByteStr) {
         visit_lit_byte_str_mut(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lit_char_mut(&mut self, i: &mut LitChar) {
         visit_lit_char_mut(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lit_float_mut(&mut self, i: &mut LitFloat) {
         visit_lit_float_mut(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lit_int_mut(&mut self, i: &mut LitInt) {
         visit_lit_int_mut(self, i)
     }
-    #[cfg(any(feature = "derive", feature = "full"))]
     fn visit_lit_str_mut(&mut self, i: &mut LitStr) {
         visit_lit_str_mut(self, i)
     }
     #[cfg(feature = "full")]
     fn visit_local_mut(&mut self, i: &mut Local) {
         visit_local_mut(self, i)
     }
     #[cfg(any(feature = "derive", feature = "full"))]
@@ -2538,17 +2529,16 @@ where
     for el in Punctuated::pairs_mut(&mut node.bounds) {
         let (it, p) = el.into_tuple();
         v.visit_lifetime_mut(it);
         if let Some(p) = p {
             tokens_helper(v, &mut p.spans);
         }
     }
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn visit_lit_mut<V>(v: &mut V, node: &mut Lit)
 where
     V: VisitMut + ?Sized,
 {
     match node {
         Lit::Str(_binding_0) => {
             v.visit_lit_str_mut(_binding_0);
         }
@@ -2570,55 +2560,48 @@ where
         Lit::Bool(_binding_0) => {
             v.visit_lit_bool_mut(_binding_0);
         }
         Lit::Verbatim(_binding_0) => {
             skip!(_binding_0);
         }
     }
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn visit_lit_bool_mut<V>(v: &mut V, node: &mut LitBool)
 where
     V: VisitMut + ?Sized,
 {
     skip!(node.value);
     v.visit_span_mut(&mut node.span);
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn visit_lit_byte_mut<V>(v: &mut V, node: &mut LitByte)
 where
     V: VisitMut + ?Sized,
 {
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn visit_lit_byte_str_mut<V>(v: &mut V, node: &mut LitByteStr)
 where
     V: VisitMut + ?Sized,
 {
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn visit_lit_char_mut<V>(v: &mut V, node: &mut LitChar)
 where
     V: VisitMut + ?Sized,
 {
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn visit_lit_float_mut<V>(v: &mut V, node: &mut LitFloat)
 where
     V: VisitMut + ?Sized,
 {
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn visit_lit_int_mut<V>(v: &mut V, node: &mut LitInt)
 where
     V: VisitMut + ?Sized,
 {
 }
-#[cfg(any(feature = "derive", feature = "full"))]
 pub fn visit_lit_str_mut<V>(v: &mut V, node: &mut LitStr)
 where
     V: VisitMut + ?Sized,
 {
 }
 #[cfg(feature = "full")]
 pub fn visit_local_mut<V>(v: &mut V, node: &mut Local)
 where
diff --git a/third_party/rust/syn/src/generics.rs b/third_party/rust/syn/src/generics.rs
--- a/third_party/rust/syn/src/generics.rs
+++ b/third_party/rust/syn/src/generics.rs
@@ -1,97 +1,108 @@
 use super::*;
 use crate::punctuated::{Iter, IterMut, Punctuated};
+#[cfg(all(feature = "printing", feature = "extra-traits"))]
+use std::fmt::{self, Debug};
+#[cfg(all(feature = "printing", feature = "extra-traits"))]
+use std::hash::{Hash, Hasher};
 
 ast_struct! {
     /// Lifetimes and type parameters attached to a declaration of a function,
     /// enum, trait, etc.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
-    #[derive(Default)]
     pub struct Generics {
         pub lt_token: Option<Token![<]>,
         pub params: Punctuated<GenericParam, Token![,]>,
         pub gt_token: Option<Token![>]>,
         pub where_clause: Option<WhereClause>,
     }
 }
 
 ast_enum_of_structs! {
     /// A generic type parameter, lifetime, or const generic: `T: Into<String>`,
     /// `'a: 'b`, `const LEN: usize`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     ///
     /// # Syntax tree enum
     ///
     /// This type is a [syntax tree enum].
     ///
     /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums
-    //
-    // TODO: change syntax-tree-enum link to an intra rustdoc link, currently
-    // blocked on https://github.com/rust-lang/rust/issues/62833
     pub enum GenericParam {
         /// A generic type parameter: `T: Into<String>`.
         Type(TypeParam),
 
         /// A lifetime definition: `'a: 'b + 'c + 'd`.
         Lifetime(LifetimeDef),
 
         /// A const generic parameter: `const LENGTH: usize`.
         Const(ConstParam),
     }
 }
 
 ast_struct! {
     /// A generic type parameter: `T: Into<String>`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct TypeParam {
         pub attrs: Vec<Attribute>,
         pub ident: Ident,
         pub colon_token: Option<Token![:]>,
         pub bounds: Punctuated<TypeParamBound, Token![+]>,
         pub eq_token: Option<Token![=]>,
         pub default: Option<Type>,
     }
 }
 
 ast_struct! {
     /// A lifetime definition: `'a: 'b + 'c + 'd`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct LifetimeDef {
         pub attrs: Vec<Attribute>,
         pub lifetime: Lifetime,
         pub colon_token: Option<Token![:]>,
         pub bounds: Punctuated<Lifetime, Token![+]>,
     }
 }
 
 ast_struct! {
     /// A const generic parameter: `const LENGTH: usize`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct ConstParam {
         pub attrs: Vec<Attribute>,
         pub const_token: Token![const],
         pub ident: Ident,
         pub colon_token: Token![:],
         pub ty: Type,
         pub eq_token: Option<Token![=]>,
         pub default: Option<Expr>,
     }
 }
 
+impl Default for Generics {
+    fn default() -> Self {
+        Generics {
+            lt_token: None,
+            params: Punctuated::new(),
+            gt_token: None,
+            where_clause: None,
+        }
+    }
+}
+
 impl Generics {
     /// Returns an
     /// <code
     ///   style="padding-right:0;">Iterator&lt;Item = &amp;</code><a
     ///   href="struct.TypeParam.html"><code
     ///   style="padding-left:0;padding-right:0;">TypeParam</code></a><code
     ///   style="padding-left:0;">&gt;</code>
     /// over the type parameters in `self.params`.
@@ -275,100 +286,148 @@ impl<'a> Iterator for ConstParamsMut<'a>
         } else {
             self.next()
         }
     }
 }
 
 /// Returned by `Generics::split_for_impl`.
 ///
-/// *This type is available if Syn is built with the `"derive"` or `"full"`
+/// *This type is available only if Syn is built with the `"derive"` or `"full"`
 /// feature and the `"printing"` feature.*
 #[cfg(feature = "printing")]
-#[cfg_attr(feature = "extra-traits", derive(Debug, Eq, PartialEq, Hash))]
-#[cfg_attr(feature = "clone-impls", derive(Clone))]
 pub struct ImplGenerics<'a>(&'a Generics);
 
 /// Returned by `Generics::split_for_impl`.
 ///
-/// *This type is available if Syn is built with the `"derive"` or `"full"`
+/// *This type is available only if Syn is built with the `"derive"` or `"full"`
 /// feature and the `"printing"` feature.*
 #[cfg(feature = "printing")]
-#[cfg_attr(feature = "extra-traits", derive(Debug, Eq, PartialEq, Hash))]
-#[cfg_attr(feature = "clone-impls", derive(Clone))]
 pub struct TypeGenerics<'a>(&'a Generics);
 
 /// Returned by `TypeGenerics::as_turbofish`.
 ///
-/// *This type is available if Syn is built with the `"derive"` or `"full"`
+/// *This type is available only if Syn is built with the `"derive"` or `"full"`
 /// feature and the `"printing"` feature.*
 #[cfg(feature = "printing")]
-#[cfg_attr(feature = "extra-traits", derive(Debug, Eq, PartialEq, Hash))]
-#[cfg_attr(feature = "clone-impls", derive(Clone))]
 pub struct Turbofish<'a>(&'a Generics);
 
 #[cfg(feature = "printing")]
 impl Generics {
     /// Split a type's generics into the pieces required for impl'ing a trait
     /// for that type.
     ///
     /// ```
     /// # use proc_macro2::{Span, Ident};
     /// # use quote::quote;
     /// #
-    /// # fn main() {
-    /// #     let generics: syn::Generics = Default::default();
-    /// #     let name = Ident::new("MyType", Span::call_site());
+    /// # let generics: syn::Generics = Default::default();
+    /// # let name = Ident::new("MyType", Span::call_site());
     /// #
     /// let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
     /// quote! {
     ///     impl #impl_generics MyTrait for #name #ty_generics #where_clause {
     ///         // ...
     ///     }
     /// }
-    /// #     ;
-    /// # }
+    /// # ;
     /// ```
     ///
-    /// *This method is available if Syn is built with the `"derive"` or
+    /// *This method is available only if Syn is built with the `"derive"` or
     /// `"full"` feature and the `"printing"` feature.*
     pub fn split_for_impl(&self) -> (ImplGenerics, TypeGenerics, Option<&WhereClause>) {
         (
             ImplGenerics(self),
             TypeGenerics(self),
             self.where_clause.as_ref(),
         )
     }
 }
 
 #[cfg(feature = "printing")]
+macro_rules! generics_wrapper_impls {
+    ($ty:ident) => {
+        #[cfg(feature = "clone-impls")]
+        impl<'a> Clone for $ty<'a> {
+            fn clone(&self) -> Self {
+                $ty(self.0)
+            }
+        }
+
+        #[cfg(feature = "extra-traits")]
+        impl<'a> Debug for $ty<'a> {
+            fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                formatter
+                    .debug_tuple(stringify!($ty))
+                    .field(self.0)
+                    .finish()
+            }
+        }
+
+        #[cfg(feature = "extra-traits")]
+        impl<'a> Eq for $ty<'a> {}
+
+        #[cfg(feature = "extra-traits")]
+        impl<'a> PartialEq for $ty<'a> {
+            fn eq(&self, other: &Self) -> bool {
+                self.0 == other.0
+            }
+        }
+
+        #[cfg(feature = "extra-traits")]
+        impl<'a> Hash for $ty<'a> {
+            fn hash<H: Hasher>(&self, state: &mut H) {
+                self.0.hash(state);
+            }
+        }
+    };
+}
+
+#[cfg(feature = "printing")]
+generics_wrapper_impls!(ImplGenerics);
+#[cfg(feature = "printing")]
+generics_wrapper_impls!(TypeGenerics);
+#[cfg(feature = "printing")]
+generics_wrapper_impls!(Turbofish);
+
+#[cfg(feature = "printing")]
 impl<'a> TypeGenerics<'a> {
     /// Turn a type's generics like `<X, Y>` into a turbofish like `::<X, Y>`.
     ///
-    /// *This method is available if Syn is built with the `"derive"` or
+    /// *This method is available only if Syn is built with the `"derive"` or
     /// `"full"` feature and the `"printing"` feature.*
     pub fn as_turbofish(&self) -> Turbofish {
         Turbofish(self.0)
     }
 }
 
 ast_struct! {
     /// A set of bound lifetimes: `for<'a, 'b, 'c>`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
-    #[derive(Default)]
     pub struct BoundLifetimes {
         pub for_token: Token![for],
         pub lt_token: Token![<],
         pub lifetimes: Punctuated<LifetimeDef, Token![,]>,
         pub gt_token: Token![>],
     }
 }
 
+impl Default for BoundLifetimes {
+    fn default() -> Self {
+        BoundLifetimes {
+            for_token: Default::default(),
+            lt_token: Default::default(),
+            lifetimes: Punctuated::new(),
+            gt_token: Default::default(),
+        }
+    }
+}
+
 impl LifetimeDef {
     pub fn new(lifetime: Lifetime) -> Self {
         LifetimeDef {
             attrs: Vec::new(),
             lifetime,
             colon_token: None,
             bounds: Punctuated::new(),
         }
@@ -386,122 +445,118 @@ impl From<Ident> for TypeParam {
             default: None,
         }
     }
 }
 
 ast_enum_of_structs! {
     /// A trait or lifetime used as a bound on a type parameter.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub enum TypeParamBound {
         Trait(TraitBound),
         Lifetime(Lifetime),
     }
 }
 
 ast_struct! {
     /// A trait used as a bound on a type parameter.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub struct TraitBound {
         pub paren_token: Option<token::Paren>,
         pub modifier: TraitBoundModifier,
         /// The `for<'a>` in `for<'a> Foo<&'a T>`
         pub lifetimes: Option<BoundLifetimes>,
         /// The `Foo<&'a T>` in `for<'a> Foo<&'a T>`
         pub path: Path,
     }
 }
 
 ast_enum! {
     /// A modifier on a trait bound, currently only used for the `?` in
     /// `?Sized`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
-    #[cfg_attr(feature = "clone-impls", derive(Copy))]
     pub enum TraitBoundModifier {
         None,
         Maybe(Token![?]),
     }
 }
 
 ast_struct! {
     /// A `where` clause in a definition: `where T: Deserialize<'de>, D:
     /// 'static`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub struct WhereClause {
         pub where_token: Token![where],
         pub predicates: Punctuated<WherePredicate, Token![,]>,
     }
 }
 
 ast_enum_of_structs! {
     /// A single predicate in a `where` clause: `T: Deserialize<'de>`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     ///
     /// # Syntax tree enum
     ///
     /// This type is a [syntax tree enum].
     ///
     /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums
-    //
-    // TODO: change syntax-tree-enum link to an intra rustdoc link, currently
-    // blocked on https://github.com/rust-lang/rust/issues/62833
     pub enum WherePredicate {
         /// A type predicate in a `where` clause: `for<'c> Foo<'c>: Trait<'c>`.
         Type(PredicateType),
 
         /// A lifetime predicate in a `where` clause: `'a: 'b + 'c`.
         Lifetime(PredicateLifetime),
 
         /// An equality predicate in a `where` clause (unsupported).
         Eq(PredicateEq),
     }
 }
 
 ast_struct! {
     /// A type predicate in a `where` clause: `for<'c> Foo<'c>: Trait<'c>`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct PredicateType {
         /// Any lifetimes from a `for` binding
         pub lifetimes: Option<BoundLifetimes>,
         /// The type being bounded
         pub bounded_ty: Type,
         pub colon_token: Token![:],
         /// Trait and lifetime bounds (`Clone+Send+'static`)
         pub bounds: Punctuated<TypeParamBound, Token![+]>,
     }
 }
 
 ast_struct! {
     /// A lifetime predicate in a `where` clause: `'a: 'b + 'c`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct PredicateLifetime {
         pub lifetime: Lifetime,
         pub colon_token: Token![:],
         pub bounds: Punctuated<Lifetime, Token![+]>,
     }
 }
 
 ast_struct! {
     /// An equality predicate in a `where` clause (unsupported).
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct PredicateEq {
         pub lhs_ty: Type,
         pub eq_token: Token![=],
         pub rhs_ty: Type,
     }
 }
 
@@ -516,38 +571,36 @@ pub mod parsing {
             if !input.peek(Token![<]) {
                 return Ok(Generics::default());
             }
 
             let lt_token: Token![<] = input.parse()?;
 
             let mut params = Punctuated::new();
             let mut allow_lifetime_param = true;
-            let mut allow_type_param = true;
             loop {
                 if input.peek(Token![>]) {
                     break;
                 }
 
                 let attrs = input.call(Attribute::parse_outer)?;
                 let lookahead = input.lookahead1();
                 if allow_lifetime_param && lookahead.peek(Lifetime) {
                     params.push_value(GenericParam::Lifetime(LifetimeDef {
                         attrs,
                         ..input.parse()?
                     }));
-                } else if allow_type_param && lookahead.peek(Ident) {
+                } else if lookahead.peek(Ident) {
                     allow_lifetime_param = false;
                     params.push_value(GenericParam::Type(TypeParam {
                         attrs,
                         ..input.parse()?
                     }));
                 } else if lookahead.peek(Token![const]) {
                     allow_lifetime_param = false;
-                    allow_type_param = false;
                     params.push_value(GenericParam::Const(ConstParam {
                         attrs,
                         ..input.parse()?
                     }));
                 } else {
                     return Err(lookahead.error());
                 }
 
@@ -660,67 +713,63 @@ pub mod parsing {
             } else {
                 Ok(None)
             }
         }
     }
 
     impl Parse for TypeParam {
         fn parse(input: ParseStream) -> Result<Self> {
-            let has_colon;
-            let has_default;
-            Ok(TypeParam {
-                attrs: input.call(Attribute::parse_outer)?,
-                ident: input.parse()?,
-                colon_token: {
-                    if input.peek(Token![:]) {
-                        has_colon = true;
-                        Some(input.parse()?)
-                    } else {
-                        has_colon = false;
-                        None
+            let attrs = input.call(Attribute::parse_outer)?;
+            let ident: Ident = input.parse()?;
+            let colon_token: Option<Token![:]> = input.parse()?;
+
+            let begin_bound = input.fork();
+            let mut is_maybe_const = false;
+            let mut bounds = Punctuated::new();
+            if colon_token.is_some() {
+                loop {
+                    if input.peek(Token![,]) || input.peek(Token![>]) || input.peek(Token![=]) {
+                        break;
+                    }
+                    if input.peek(Token![?]) && input.peek2(Token![const]) {
+                        input.parse::<Token![?]>()?;
+                        input.parse::<Token![const]>()?;
+                        is_maybe_const = true;
+                    }
+                    let value: TypeParamBound = input.parse()?;
+                    bounds.push_value(value);
+                    if !input.peek(Token![+]) {
+                        break;
                     }
-                },
-                bounds: {
-                    let mut bounds = Punctuated::new();
-                    if has_colon {
-                        loop {
-                            if input.peek(Token![,])
-                                || input.peek(Token![>])
-                                || input.peek(Token![=])
-                            {
-                                break;
-                            }
-                            let value = input.parse()?;
-                            bounds.push_value(value);
-                            if !input.peek(Token![+]) {
-                                break;
-                            }
-                            let punct = input.parse()?;
-                            bounds.push_punct(punct);
-                        }
-                    }
-                    bounds
-                },
-                eq_token: {
-                    if input.peek(Token![=]) {
-                        has_default = true;
-                        Some(input.parse()?)
-                    } else {
-                        has_default = false;
-                        None
-                    }
-                },
-                default: {
-                    if has_default {
-                        Some(input.parse()?)
-                    } else {
-                        None
-                    }
-                },
+                    let punct: Token![+] = input.parse()?;
+                    bounds.push_punct(punct);
+                }
+            }
+
+            let mut eq_token: Option<Token![=]> = input.parse()?;
+            let mut default = if eq_token.is_some() {
+                Some(input.parse::<Type>()?)
+            } else {
+                None
+            };
+
+            if is_maybe_const {
+                bounds.clear();
+                eq_token = None;
+                default = Some(Type::Verbatim(verbatim::between(begin_bound, input)));
+            }
+
+            Ok(TypeParam {
+                attrs,
+                ident,
+                colon_token,
+                bounds,
+                eq_token,
+                default,
             })
         }
     }
 
     impl Parse for TypeParamBound {
         fn parse(input: ParseStream) -> Result<Self> {
             if input.peek(Lifetime) {
                 return input.parse().map(TypeParamBound::Lifetime);
@@ -893,16 +942,18 @@ pub mod parsing {
     }
 }
 
 #[cfg(feature = "printing")]
 mod printing {
     use super::*;
 
     use proc_macro2::TokenStream;
+    #[cfg(feature = "full")]
+    use proc_macro2::TokenTree;
     use quote::{ToTokens, TokenStreamExt};
 
     use crate::attr::FilterAttrs;
     use crate::print::TokensOrDefault;
 
     impl ToTokens for Generics {
         fn to_tokens(&self, tokens: &mut TokenStream) {
             if self.params.is_empty() {
@@ -1075,19 +1126,35 @@ mod printing {
     impl ToTokens for TypeParam {
         fn to_tokens(&self, tokens: &mut TokenStream) {
             tokens.append_all(self.attrs.outer());
             self.ident.to_tokens(tokens);
             if !self.bounds.is_empty() {
                 TokensOrDefault(&self.colon_token).to_tokens(tokens);
                 self.bounds.to_tokens(tokens);
             }
-            if self.default.is_some() {
+            if let Some(default) = &self.default {
+                #[cfg(feature = "full")]
+                {
+                    if self.eq_token.is_none() {
+                        if let Type::Verbatim(default) = default {
+                            let mut iter = default.clone().into_iter();
+                            match (iter.next(), iter.next()) {
+                                (Some(TokenTree::Punct(ref q)), Some(TokenTree::Ident(ref c)))
+                                    if q.as_char() == '?' && c == "const" =>
+                                {
+                                    return default.to_tokens(tokens);
+                                }
+                                _ => {}
+                            }
+                        }
+                    }
+                }
                 TokensOrDefault(&self.eq_token).to_tokens(tokens);
-                self.default.to_tokens(tokens);
+                default.to_tokens(tokens);
             }
         }
     }
 
     impl ToTokens for TraitBound {
         fn to_tokens(&self, tokens: &mut TokenStream) {
             let to_tokens = |tokens: &mut TokenStream| {
                 self.modifier.to_tokens(tokens);
@@ -1112,19 +1179,19 @@ mod printing {
 
     impl ToTokens for ConstParam {
         fn to_tokens(&self, tokens: &mut TokenStream) {
             tokens.append_all(self.attrs.outer());
             self.const_token.to_tokens(tokens);
             self.ident.to_tokens(tokens);
             self.colon_token.to_tokens(tokens);
             self.ty.to_tokens(tokens);
-            if self.default.is_some() {
+            if let Some(default) = &self.default {
                 TokensOrDefault(&self.eq_token).to_tokens(tokens);
-                self.default.to_tokens(tokens);
+                default.to_tokens(tokens);
             }
         }
     }
 
     impl ToTokens for WhereClause {
         fn to_tokens(&self, tokens: &mut TokenStream) {
             if !self.predicates.is_empty() {
                 self.where_token.to_tokens(tokens);
diff --git a/third_party/rust/syn/src/item.rs b/third_party/rust/syn/src/item.rs
--- a/third_party/rust/syn/src/item.rs
+++ b/third_party/rust/syn/src/item.rs
@@ -1,32 +1,30 @@
 use super::*;
-use crate::derive::{Data, DeriveInput};
+use crate::derive::{Data, DataEnum, DataStruct, DataUnion, DeriveInput};
 use crate::punctuated::Punctuated;
 use proc_macro2::TokenStream;
 
-#[cfg(feature = "extra-traits")]
-use crate::tt::TokenStreamHelper;
-#[cfg(feature = "extra-traits")]
-use std::hash::{Hash, Hasher};
+#[cfg(feature = "parsing")]
+use std::mem;
 
 ast_enum_of_structs! {
     /// Things that can appear directly inside of a module or scope.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     ///
     /// # Syntax tree enum
     ///
     /// This type is a [syntax tree enum].
     ///
     /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums
     //
     // TODO: change syntax-tree-enum link to an intra rustdoc link, currently
     // blocked on https://github.com/rust-lang/rust/issues/62833
-    pub enum Item #manual_extra_traits {
+    pub enum Item {
         /// A constant item: `const MAX: u16 = 65535`.
         Const(ItemConst),
 
         /// An enum definition: `enum Foo<A, B> { A(A), B(B) }`.
         Enum(ItemEnum),
 
         /// An `extern crate` item: `extern crate serde`.
         ExternCrate(ItemExternCrate),
@@ -78,90 +76,90 @@ ast_enum_of_structs! {
         #[doc(hidden)]
         __Nonexhaustive,
     }
 }
 
 ast_struct! {
     /// A constant item: `const MAX: u16 = 65535`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ItemConst {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub const_token: Token![const],
         pub ident: Ident,
         pub colon_token: Token![:],
         pub ty: Box<Type>,
         pub eq_token: Token![=],
         pub expr: Box<Expr>,
         pub semi_token: Token![;],
     }
 }
 
 ast_struct! {
     /// An enum definition: `enum Foo<A, B> { A(A), B(B) }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ItemEnum {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub enum_token: Token![enum],
         pub ident: Ident,
         pub generics: Generics,
         pub brace_token: token::Brace,
         pub variants: Punctuated<Variant, Token![,]>,
     }
 }
 
 ast_struct! {
     /// An `extern crate` item: `extern crate serde`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ItemExternCrate {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub extern_token: Token![extern],
         pub crate_token: Token![crate],
         pub ident: Ident,
         pub rename: Option<(Token![as], Ident)>,
         pub semi_token: Token![;],
     }
 }
 
 ast_struct! {
     /// A free-standing function: `fn process(n: usize) -> Result<()> { ...
     /// }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ItemFn {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub sig: Signature,
         pub block: Box<Block>,
     }
 }
 
 ast_struct! {
     /// A block of foreign items: `extern "C" { ... }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ItemForeignMod {
         pub attrs: Vec<Attribute>,
         pub abi: Abi,
         pub brace_token: token::Brace,
         pub items: Vec<ForeignItem>,
     }
 }
 
 ast_struct! {
     /// An impl block providing trait or associated items: `impl<A> Trait
     /// for Data<A> { ... }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ItemImpl {
         pub attrs: Vec<Attribute>,
         pub defaultness: Option<Token![default]>,
         pub unsafety: Option<Token![unsafe]>,
         pub impl_token: Token![impl],
         pub generics: Generics,
         /// Trait this impl implements.
         pub trait_: Option<(Option<Token![!]>, Path, Token![for])>,
@@ -170,57 +168,57 @@ ast_struct! {
         pub brace_token: token::Brace,
         pub items: Vec<ImplItem>,
     }
 }
 
 ast_struct! {
     /// A macro invocation, which includes `macro_rules!` definitions.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ItemMacro {
         pub attrs: Vec<Attribute>,
         /// The `example` in `macro_rules! example { ... }`.
         pub ident: Option<Ident>,
         pub mac: Macro,
         pub semi_token: Option<Token![;]>,
     }
 }
 
 ast_struct! {
     /// A 2.0-style declarative macro introduced by the `macro` keyword.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
-    pub struct ItemMacro2 #manual_extra_traits {
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    pub struct ItemMacro2 {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub macro_token: Token![macro],
         pub ident: Ident,
         pub rules: TokenStream,
     }
 }
 
 ast_struct! {
     /// A module or module declaration: `mod m` or `mod m { ... }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ItemMod {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub mod_token: Token![mod],
         pub ident: Ident,
         pub content: Option<(token::Brace, Vec<Item>)>,
         pub semi: Option<Token![;]>,
     }
 }
 
 ast_struct! {
     /// A static item: `static BIKE: Shed = Shed(42)`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ItemStatic {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub static_token: Token![static],
         pub mutability: Option<Token![mut]>,
         pub ident: Ident,
         pub colon_token: Token![:],
         pub ty: Box<Type>,
@@ -228,32 +226,32 @@ ast_struct! {
         pub expr: Box<Expr>,
         pub semi_token: Token![;],
     }
 }
 
 ast_struct! {
     /// A struct definition: `struct Foo<A> { x: A }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ItemStruct {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub struct_token: Token![struct],
         pub ident: Ident,
         pub generics: Generics,
         pub fields: Fields,
         pub semi_token: Option<Token![;]>,
     }
 }
 
 ast_struct! {
     /// A trait definition: `pub trait Iterator { ... }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ItemTrait {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub unsafety: Option<Token![unsafe]>,
         pub auto_token: Option<Token![auto]>,
         pub trait_token: Token![trait],
         pub ident: Ident,
         pub generics: Generics,
@@ -262,212 +260,99 @@ ast_struct! {
         pub brace_token: token::Brace,
         pub items: Vec<TraitItem>,
     }
 }
 
 ast_struct! {
     /// A trait alias: `pub trait SharableIterator = Iterator + Sync`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ItemTraitAlias {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub trait_token: Token![trait],
         pub ident: Ident,
         pub generics: Generics,
         pub eq_token: Token![=],
         pub bounds: Punctuated<TypeParamBound, Token![+]>,
         pub semi_token: Token![;],
     }
 }
 
 ast_struct! {
     /// A type alias: `type Result<T> = std::result::Result<T, MyError>`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ItemType {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub type_token: Token![type],
         pub ident: Ident,
         pub generics: Generics,
         pub eq_token: Token![=],
         pub ty: Box<Type>,
         pub semi_token: Token![;],
     }
 }
 
 ast_struct! {
     /// A union definition: `union Foo<A, B> { x: A, y: B }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ItemUnion {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub union_token: Token![union],
         pub ident: Ident,
         pub generics: Generics,
         pub fields: FieldsNamed,
     }
 }
 
 ast_struct! {
     /// A use declaration: `use std::collections::HashMap`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ItemUse {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub use_token: Token![use],
         pub leading_colon: Option<Token![::]>,
         pub tree: UseTree,
         pub semi_token: Token![;],
     }
 }
 
-#[cfg(feature = "extra-traits")]
-impl Eq for Item {}
-
-#[cfg(feature = "extra-traits")]
-impl PartialEq for Item {
-    fn eq(&self, other: &Self) -> bool {
-        match (self, other) {
-            (Item::Const(this), Item::Const(other)) => this == other,
-            (Item::Enum(this), Item::Enum(other)) => this == other,
-            (Item::ExternCrate(this), Item::ExternCrate(other)) => this == other,
-            (Item::Fn(this), Item::Fn(other)) => this == other,
-            (Item::ForeignMod(this), Item::ForeignMod(other)) => this == other,
-            (Item::Impl(this), Item::Impl(other)) => this == other,
-            (Item::Macro(this), Item::Macro(other)) => this == other,
-            (Item::Macro2(this), Item::Macro2(other)) => this == other,
-            (Item::Mod(this), Item::Mod(other)) => this == other,
-            (Item::Static(this), Item::Static(other)) => this == other,
-            (Item::Struct(this), Item::Struct(other)) => this == other,
-            (Item::Trait(this), Item::Trait(other)) => this == other,
-            (Item::TraitAlias(this), Item::TraitAlias(other)) => this == other,
-            (Item::Type(this), Item::Type(other)) => this == other,
-            (Item::Union(this), Item::Union(other)) => this == other,
-            (Item::Use(this), Item::Use(other)) => this == other,
-            (Item::Verbatim(this), Item::Verbatim(other)) => {
-                TokenStreamHelper(this) == TokenStreamHelper(other)
-            }
-            _ => false,
-        }
-    }
-}
-
-#[cfg(feature = "extra-traits")]
-impl Hash for Item {
-    fn hash<H>(&self, state: &mut H)
-    where
-        H: Hasher,
-    {
+impl Item {
+    #[cfg(feature = "parsing")]
+    pub(crate) fn replace_attrs(&mut self, new: Vec<Attribute>) -> Vec<Attribute> {
         match self {
-            Item::Const(item) => {
-                state.write_u8(0);
-                item.hash(state);
-            }
-            Item::Enum(item) => {
-                state.write_u8(1);
-                item.hash(state);
-            }
-            Item::ExternCrate(item) => {
-                state.write_u8(2);
-                item.hash(state);
-            }
-            Item::Fn(item) => {
-                state.write_u8(3);
-                item.hash(state);
-            }
-            Item::ForeignMod(item) => {
-                state.write_u8(4);
-                item.hash(state);
-            }
-            Item::Impl(item) => {
-                state.write_u8(5);
-                item.hash(state);
-            }
-            Item::Macro(item) => {
-                state.write_u8(6);
-                item.hash(state);
-            }
-            Item::Macro2(item) => {
-                state.write_u8(7);
-                item.hash(state);
-            }
-            Item::Mod(item) => {
-                state.write_u8(8);
-                item.hash(state);
-            }
-            Item::Static(item) => {
-                state.write_u8(9);
-                item.hash(state);
-            }
-            Item::Struct(item) => {
-                state.write_u8(10);
-                item.hash(state);
-            }
-            Item::Trait(item) => {
-                state.write_u8(11);
-                item.hash(state);
-            }
-            Item::TraitAlias(item) => {
-                state.write_u8(12);
-                item.hash(state);
-            }
-            Item::Type(item) => {
-                state.write_u8(13);
-                item.hash(state);
-            }
-            Item::Union(item) => {
-                state.write_u8(14);
-                item.hash(state);
-            }
-            Item::Use(item) => {
-                state.write_u8(15);
-                item.hash(state);
-            }
-            Item::Verbatim(item) => {
-                state.write_u8(16);
-                TokenStreamHelper(item).hash(state);
-            }
+            Item::ExternCrate(ItemExternCrate { attrs, .. })
+            | Item::Use(ItemUse { attrs, .. })
+            | Item::Static(ItemStatic { attrs, .. })
+            | Item::Const(ItemConst { attrs, .. })
+            | Item::Fn(ItemFn { attrs, .. })
+            | Item::Mod(ItemMod { attrs, .. })
+            | Item::ForeignMod(ItemForeignMod { attrs, .. })
+            | Item::Type(ItemType { attrs, .. })
+            | Item::Struct(ItemStruct { attrs, .. })
+            | Item::Enum(ItemEnum { attrs, .. })
+            | Item::Union(ItemUnion { attrs, .. })
+            | Item::Trait(ItemTrait { attrs, .. })
+            | Item::TraitAlias(ItemTraitAlias { attrs, .. })
+            | Item::Impl(ItemImpl { attrs, .. })
+            | Item::Macro(ItemMacro { attrs, .. })
+            | Item::Macro2(ItemMacro2 { attrs, .. }) => mem::replace(attrs, new),
+            Item::Verbatim(_) => Vec::new(),
             Item::__Nonexhaustive => unreachable!(),
         }
     }
 }
 
-#[cfg(feature = "extra-traits")]
-impl Eq for ItemMacro2 {}
-
-#[cfg(feature = "extra-traits")]
-impl PartialEq for ItemMacro2 {
-    fn eq(&self, other: &Self) -> bool {
-        self.attrs == other.attrs
-            && self.vis == other.vis
-            && self.macro_token == other.macro_token
-            && self.ident == other.ident
-            && TokenStreamHelper(&self.rules) == TokenStreamHelper(&other.rules)
-    }
-}
-
-#[cfg(feature = "extra-traits")]
-impl Hash for ItemMacro2 {
-    fn hash<H>(&self, state: &mut H)
-    where
-        H: Hasher,
-    {
-        self.attrs.hash(state);
-        self.vis.hash(state);
-        self.macro_token.hash(state);
-        self.ident.hash(state);
-        TokenStreamHelper(&self.rules).hash(state);
-    }
-}
-
 impl From<DeriveInput> for Item {
     fn from(input: DeriveInput) -> Item {
         match input.data {
             Data::Struct(data) => Item::Struct(ItemStruct {
                 attrs: input.attrs,
                 vis: input.vis,
                 struct_token: data.struct_token,
                 ident: input.ident,
@@ -491,20 +376,67 @@ impl From<DeriveInput> for Item {
                 ident: input.ident,
                 generics: input.generics,
                 fields: data.fields,
             }),
         }
     }
 }
 
+impl From<ItemStruct> for DeriveInput {
+    fn from(input: ItemStruct) -> DeriveInput {
+        DeriveInput {
+            attrs: input.attrs,
+            vis: input.vis,
+            ident: input.ident,
+            generics: input.generics,
+            data: Data::Struct(DataStruct {
+                struct_token: input.struct_token,
+                fields: input.fields,
+                semi_token: input.semi_token,
+            }),
+        }
+    }
+}
+
+impl From<ItemEnum> for DeriveInput {
+    fn from(input: ItemEnum) -> DeriveInput {
+        DeriveInput {
+            attrs: input.attrs,
+            vis: input.vis,
+            ident: input.ident,
+            generics: input.generics,
+            data: Data::Enum(DataEnum {
+                enum_token: input.enum_token,
+                brace_token: input.brace_token,
+                variants: input.variants,
+            }),
+        }
+    }
+}
+
+impl From<ItemUnion> for DeriveInput {
+    fn from(input: ItemUnion) -> DeriveInput {
+        DeriveInput {
+            attrs: input.attrs,
+            vis: input.vis,
+            ident: input.ident,
+            generics: input.generics,
+            data: Data::Union(DataUnion {
+                union_token: input.union_token,
+                fields: input.fields,
+            }),
+        }
+    }
+}
+
 ast_enum_of_structs! {
     /// A suffix of an import tree in a `use` item: `Type as Renamed` or `*`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     ///
     /// # Syntax tree enum
     ///
     /// This type is a [syntax tree enum].
     ///
     /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums
     //
     // TODO: change syntax-tree-enum link to an intra rustdoc link, currently
@@ -525,77 +457,77 @@ ast_enum_of_structs! {
         /// A braced group of imports in a `use` item: `{A, B, C}`.
         Group(UseGroup),
     }
 }
 
 ast_struct! {
     /// A path prefix of imports in a `use` item: `std::...`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct UsePath {
         pub ident: Ident,
         pub colon2_token: Token![::],
         pub tree: Box<UseTree>,
     }
 }
 
 ast_struct! {
     /// An identifier imported by a `use` item: `HashMap`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct UseName {
         pub ident: Ident,
     }
 }
 
 ast_struct! {
     /// An renamed identifier imported by a `use` item: `HashMap as Map`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct UseRename {
         pub ident: Ident,
         pub as_token: Token![as],
         pub rename: Ident,
     }
 }
 
 ast_struct! {
     /// A glob import in a `use` item: `*`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct UseGlob {
         pub star_token: Token![*],
     }
 }
 
 ast_struct! {
     /// A braced group of imports in a `use` item: `{A, B, C}`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct UseGroup {
         pub brace_token: token::Brace,
         pub items: Punctuated<UseTree, Token![,]>,
     }
 }
 
 ast_enum_of_structs! {
     /// An item within an `extern` block.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     ///
     /// # Syntax tree enum
     ///
     /// This type is a [syntax tree enum].
     ///
     /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums
     //
     // TODO: change syntax-tree-enum link to an intra rustdoc link, currently
     // blocked on https://github.com/rust-lang/rust/issues/62833
-    pub enum ForeignItem #manual_extra_traits {
+    pub enum ForeignItem {
         /// A foreign function in an `extern` block.
         Fn(ForeignItemFn),
 
         /// A foreign static item in an `extern` block: `static ext: u8`.
         Static(ForeignItemStatic),
 
         /// A foreign type in an `extern` block: `type void`.
         Type(ForeignItemType),
@@ -609,130 +541,79 @@ ast_enum_of_structs! {
         #[doc(hidden)]
         __Nonexhaustive,
     }
 }
 
 ast_struct! {
     /// A foreign function in an `extern` block.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ForeignItemFn {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub sig: Signature,
         pub semi_token: Token![;],
     }
 }
 
 ast_struct! {
     /// A foreign static item in an `extern` block: `static ext: u8`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ForeignItemStatic {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub static_token: Token![static],
         pub mutability: Option<Token![mut]>,
         pub ident: Ident,
         pub colon_token: Token![:],
         pub ty: Box<Type>,
         pub semi_token: Token![;],
     }
 }
 
 ast_struct! {
     /// A foreign type in an `extern` block: `type void`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ForeignItemType {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub type_token: Token![type],
         pub ident: Ident,
         pub semi_token: Token![;],
     }
 }
 
 ast_struct! {
     /// A macro invocation within an extern block.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ForeignItemMacro {
         pub attrs: Vec<Attribute>,
         pub mac: Macro,
         pub semi_token: Option<Token![;]>,
     }
 }
 
-#[cfg(feature = "extra-traits")]
-impl Eq for ForeignItem {}
-
-#[cfg(feature = "extra-traits")]
-impl PartialEq for ForeignItem {
-    fn eq(&self, other: &Self) -> bool {
-        match (self, other) {
-            (ForeignItem::Fn(this), ForeignItem::Fn(other)) => this == other,
-            (ForeignItem::Static(this), ForeignItem::Static(other)) => this == other,
-            (ForeignItem::Type(this), ForeignItem::Type(other)) => this == other,
-            (ForeignItem::Macro(this), ForeignItem::Macro(other)) => this == other,
-            (ForeignItem::Verbatim(this), ForeignItem::Verbatim(other)) => {
-                TokenStreamHelper(this) == TokenStreamHelper(other)
-            }
-            _ => false,
-        }
-    }
-}
-
-#[cfg(feature = "extra-traits")]
-impl Hash for ForeignItem {
-    fn hash<H>(&self, state: &mut H)
-    where
-        H: Hasher,
-    {
-        match self {
-            ForeignItem::Fn(item) => {
-                state.write_u8(0);
-                item.hash(state);
-            }
-            ForeignItem::Static(item) => {
-                state.write_u8(1);
-                item.hash(state);
-            }
-            ForeignItem::Type(item) => {
-                state.write_u8(2);
-                item.hash(state);
-            }
-            ForeignItem::Macro(item) => {
-                state.write_u8(3);
-                item.hash(state);
-            }
-            ForeignItem::Verbatim(item) => {
-                state.write_u8(4);
-                TokenStreamHelper(item).hash(state);
-            }
-            ForeignItem::__Nonexhaustive => unreachable!(),
-        }
-    }
-}
-
 ast_enum_of_structs! {
     /// An item declaration within the definition of a trait.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     ///
     /// # Syntax tree enum
     ///
     /// This type is a [syntax tree enum].
     ///
     /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums
     //
     // TODO: change syntax-tree-enum link to an intra rustdoc link, currently
     // blocked on https://github.com/rust-lang/rust/issues/62833
-    pub enum TraitItem #manual_extra_traits {
+    pub enum TraitItem {
         /// An associated constant within the definition of a trait.
         Const(TraitItemConst),
 
         /// A trait method within the definition of a trait.
         Method(TraitItemMethod),
 
         /// An associated type within the definition of a trait.
         Type(TraitItemType),
@@ -746,132 +627,81 @@ ast_enum_of_structs! {
         #[doc(hidden)]
         __Nonexhaustive,
     }
 }
 
 ast_struct! {
     /// An associated constant within the definition of a trait.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct TraitItemConst {
         pub attrs: Vec<Attribute>,
         pub const_token: Token![const],
         pub ident: Ident,
         pub colon_token: Token![:],
         pub ty: Type,
         pub default: Option<(Token![=], Expr)>,
         pub semi_token: Token![;],
     }
 }
 
 ast_struct! {
     /// A trait method within the definition of a trait.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct TraitItemMethod {
         pub attrs: Vec<Attribute>,
         pub sig: Signature,
         pub default: Option<Block>,
         pub semi_token: Option<Token![;]>,
     }
 }
 
 ast_struct! {
     /// An associated type within the definition of a trait.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct TraitItemType {
         pub attrs: Vec<Attribute>,
         pub type_token: Token![type],
         pub ident: Ident,
         pub generics: Generics,
         pub colon_token: Option<Token![:]>,
         pub bounds: Punctuated<TypeParamBound, Token![+]>,
         pub default: Option<(Token![=], Type)>,
         pub semi_token: Token![;],
     }
 }
 
 ast_struct! {
     /// A macro invocation within the definition of a trait.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct TraitItemMacro {
         pub attrs: Vec<Attribute>,
         pub mac: Macro,
         pub semi_token: Option<Token![;]>,
     }
 }
 
-#[cfg(feature = "extra-traits")]
-impl Eq for TraitItem {}
-
-#[cfg(feature = "extra-traits")]
-impl PartialEq for TraitItem {
-    fn eq(&self, other: &Self) -> bool {
-        match (self, other) {
-            (TraitItem::Const(this), TraitItem::Const(other)) => this == other,
-            (TraitItem::Method(this), TraitItem::Method(other)) => this == other,
-            (TraitItem::Type(this), TraitItem::Type(other)) => this == other,
-            (TraitItem::Macro(this), TraitItem::Macro(other)) => this == other,
-            (TraitItem::Verbatim(this), TraitItem::Verbatim(other)) => {
-                TokenStreamHelper(this) == TokenStreamHelper(other)
-            }
-            _ => false,
-        }
-    }
-}
-
-#[cfg(feature = "extra-traits")]
-impl Hash for TraitItem {
-    fn hash<H>(&self, state: &mut H)
-    where
-        H: Hasher,
-    {
-        match self {
-            TraitItem::Const(item) => {
-                state.write_u8(0);
-                item.hash(state);
-            }
-            TraitItem::Method(item) => {
-                state.write_u8(1);
-                item.hash(state);
-            }
-            TraitItem::Type(item) => {
-                state.write_u8(2);
-                item.hash(state);
-            }
-            TraitItem::Macro(item) => {
-                state.write_u8(3);
-                item.hash(state);
-            }
-            TraitItem::Verbatim(item) => {
-                state.write_u8(4);
-                TokenStreamHelper(item).hash(state);
-            }
-            TraitItem::__Nonexhaustive => unreachable!(),
-        }
-    }
-}
-
 ast_enum_of_structs! {
     /// An item within an impl block.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     ///
     /// # Syntax tree enum
     ///
     /// This type is a [syntax tree enum].
     ///
     /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums
     //
     // TODO: change syntax-tree-enum link to an intra rustdoc link, currently
     // blocked on https://github.com/rust-lang/rust/issues/62833
-    pub enum ImplItem #manual_extra_traits {
+    pub enum ImplItem {
         /// An associated constant within an impl block.
         Const(ImplItemConst),
 
         /// A method within an impl block.
         Method(ImplItemMethod),
 
         /// An associated type within an impl block.
         Type(ImplItemType),
@@ -885,17 +715,17 @@ ast_enum_of_structs! {
         #[doc(hidden)]
         __Nonexhaustive,
     }
 }
 
 ast_struct! {
     /// An associated constant within an impl block.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ImplItemConst {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub defaultness: Option<Token![default]>,
         pub const_token: Token![const],
         pub ident: Ident,
         pub colon_token: Token![:],
         pub ty: Type,
@@ -903,144 +733,117 @@ ast_struct! {
         pub expr: Expr,
         pub semi_token: Token![;],
     }
 }
 
 ast_struct! {
     /// A method within an impl block.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ImplItemMethod {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub defaultness: Option<Token![default]>,
         pub sig: Signature,
         pub block: Block,
     }
 }
 
 ast_struct! {
     /// An associated type within an impl block.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ImplItemType {
         pub attrs: Vec<Attribute>,
         pub vis: Visibility,
         pub defaultness: Option<Token![default]>,
         pub type_token: Token![type],
         pub ident: Ident,
         pub generics: Generics,
         pub eq_token: Token![=],
         pub ty: Type,
         pub semi_token: Token![;],
     }
 }
 
 ast_struct! {
     /// A macro invocation within an impl block.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct ImplItemMacro {
         pub attrs: Vec<Attribute>,
         pub mac: Macro,
         pub semi_token: Option<Token![;]>,
     }
 }
 
-#[cfg(feature = "extra-traits")]
-impl Eq for ImplItem {}
-
-#[cfg(feature = "extra-traits")]
-impl PartialEq for ImplItem {
-    fn eq(&self, other: &Self) -> bool {
-        match (self, other) {
-            (ImplItem::Const(this), ImplItem::Const(other)) => this == other,
-            (ImplItem::Method(this), ImplItem::Method(other)) => this == other,
-            (ImplItem::Type(this), ImplItem::Type(other)) => this == other,
-            (ImplItem::Macro(this), ImplItem::Macro(other)) => this == other,
-            (ImplItem::Verbatim(this), ImplItem::Verbatim(other)) => {
-                TokenStreamHelper(this) == TokenStreamHelper(other)
-            }
-            _ => false,
-        }
-    }
-}
-
-#[cfg(feature = "extra-traits")]
-impl Hash for ImplItem {
-    fn hash<H>(&self, state: &mut H)
-    where
-        H: Hasher,
-    {
-        match self {
-            ImplItem::Const(item) => {
-                state.write_u8(0);
-                item.hash(state);
-            }
-            ImplItem::Method(item) => {
-                state.write_u8(1);
-                item.hash(state);
-            }
-            ImplItem::Type(item) => {
-                state.write_u8(2);
-                item.hash(state);
-            }
-            ImplItem::Macro(item) => {
-                state.write_u8(3);
-                item.hash(state);
-            }
-            ImplItem::Verbatim(item) => {
-                state.write_u8(4);
-                TokenStreamHelper(item).hash(state);
-            }
-            ImplItem::__Nonexhaustive => unreachable!(),
-        }
-    }
-}
-
 ast_struct! {
     /// A function signature in a trait or implementation: `unsafe fn
     /// initialize(&self)`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct Signature {
         pub constness: Option<Token![const]>,
         pub asyncness: Option<Token![async]>,
         pub unsafety: Option<Token![unsafe]>,
         pub abi: Option<Abi>,
         pub fn_token: Token![fn],
         pub ident: Ident,
         pub generics: Generics,
         pub paren_token: token::Paren,
         pub inputs: Punctuated<FnArg, Token![,]>,
         pub variadic: Option<Variadic>,
         pub output: ReturnType,
     }
 }
 
+impl Signature {
+    /// A method's `self` receiver, such as `&self` or `self: Box<Self>`.
+    pub fn receiver(&self) -> Option<&FnArg> {
+        let arg = self.inputs.first()?;
+        match arg {
+            FnArg::Receiver(_) => Some(arg),
+            FnArg::Typed(PatType { pat, .. }) => {
+                if let Pat::Ident(PatIdent { ident, .. }) = &**pat {
+                    if ident == "self" {
+                        return Some(arg);
+                    }
+                }
+                None
+            }
+        }
+    }
+}
+
 ast_enum_of_structs! {
     /// An argument in a function signature: the `n: usize` in `fn f(n: usize)`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub enum FnArg {
         /// The `self` argument of an associated method, whether taken by value
         /// or by reference.
+        ///
+        /// Note that `self` receivers with a specified type, such as `self:
+        /// Box<Self>`, are parsed as a `FnArg::Typed`.
         Receiver(Receiver),
 
         /// A function argument accepted by pattern and type.
         Typed(PatType),
     }
 }
 
 ast_struct! {
     /// The `self` argument of an associated method, whether taken by value
     /// or by reference.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// Note that `self` receivers with a specified type, such as `self:
+    /// Box<Self>`, are parsed as a `FnArg::Typed`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct Receiver {
         pub attrs: Vec<Attribute>,
         pub reference: Option<(Token![&], Option<Lifetime>)>,
         pub mutability: Option<Token![mut]>,
         pub self_token: Token![self],
     }
 }
 
@@ -1051,149 +854,233 @@ impl Receiver {
 }
 
 #[cfg(feature = "parsing")]
 pub mod parsing {
     use super::*;
 
     use crate::ext::IdentExt;
     use crate::parse::discouraged::Speculative;
-    use crate::parse::{Parse, ParseStream, Result};
+    use crate::parse::{Parse, ParseBuffer, ParseStream, Result};
+    use crate::token::Brace;
     use proc_macro2::{Delimiter, Group, Punct, Spacing, TokenTree};
     use std::iter::{self, FromIterator};
 
     crate::custom_keyword!(existential);
 
     impl Parse for Item {
         fn parse(input: ParseStream) -> Result<Self> {
+            let begin = input.fork();
             let mut attrs = input.call(Attribute::parse_outer)?;
             let ahead = input.fork();
             let vis: Visibility = ahead.parse()?;
 
             let lookahead = ahead.lookahead1();
-            let mut item = if lookahead.peek(Token![extern]) {
+            let mut item = if lookahead.peek(Token![fn]) || peek_signature(&ahead) {
+                let vis: Visibility = input.parse()?;
+                let sig = parse_signature(input)?;
+                if input.peek(Token![;]) {
+                    input.parse::<Token![;]>()?;
+                    Ok(Item::Verbatim(verbatim::between(begin, input)))
+                } else {
+                    parse_rest_of_fn(input, Vec::new(), vis, sig).map(Item::Fn)
+                }
+            } else if lookahead.peek(Token![extern]) {
                 ahead.parse::<Token![extern]>()?;
                 let lookahead = ahead.lookahead1();
                 if lookahead.peek(Token![crate]) {
                     input.parse().map(Item::ExternCrate)
-                } else if lookahead.peek(Token![fn]) {
-                    input.parse().map(Item::Fn)
                 } else if lookahead.peek(token::Brace) {
                     input.parse().map(Item::ForeignMod)
                 } else if lookahead.peek(LitStr) {
                     ahead.parse::<LitStr>()?;
                     let lookahead = ahead.lookahead1();
                     if lookahead.peek(token::Brace) {
                         input.parse().map(Item::ForeignMod)
-                    } else if lookahead.peek(Token![fn]) {
-                        input.parse().map(Item::Fn)
                     } else {
                         Err(lookahead.error())
                     }
                 } else {
                     Err(lookahead.error())
                 }
             } else if lookahead.peek(Token![use]) {
                 input.parse().map(Item::Use)
             } else if lookahead.peek(Token![static]) {
-                input.parse().map(Item::Static)
+                let vis = input.parse()?;
+                let static_token = input.parse()?;
+                let mutability = input.parse()?;
+                let ident = input.parse()?;
+                let colon_token = input.parse()?;
+                let ty = input.parse()?;
+                if input.peek(Token![;]) {
+                    input.parse::<Token![;]>()?;
+                    Ok(Item::Verbatim(verbatim::between(begin, input)))
+                } else {
+                    Ok(Item::Static(ItemStatic {
+                        attrs: Vec::new(),
+                        vis,
+                        static_token,
+                        mutability,
+                        ident,
+                        colon_token,
+                        ty,
+                        eq_token: input.parse()?,
+                        expr: input.parse()?,
+                        semi_token: input.parse()?,
+                    }))
+                }
             } else if lookahead.peek(Token![const]) {
                 ahead.parse::<Token![const]>()?;
                 let lookahead = ahead.lookahead1();
                 if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
-                    input.parse().map(Item::Const)
-                } else if lookahead.peek(Token![unsafe])
-                    || lookahead.peek(Token![async])
-                    || lookahead.peek(Token![extern])
-                    || lookahead.peek(Token![fn])
-                {
-                    input.parse().map(Item::Fn)
+                    let vis = input.parse()?;
+                    let const_token = input.parse()?;
+                    let ident = {
+                        let lookahead = input.lookahead1();
+                        if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                            input.call(Ident::parse_any)?
+                        } else {
+                            return Err(lookahead.error());
+                        }
+                    };
+                    let colon_token = input.parse()?;
+                    let ty = input.parse()?;
+                    if input.peek(Token![;]) {
+                        input.parse::<Token![;]>()?;
+                        Ok(Item::Verbatim(verbatim::between(begin, input)))
+                    } else {
+                        Ok(Item::Const(ItemConst {
+                            attrs: Vec::new(),
+                            vis,
+                            const_token,
+                            ident,
+                            colon_token,
+                            ty,
+                            eq_token: input.parse()?,
+                            expr: input.parse()?,
+                            semi_token: input.parse()?,
+                        }))
+                    }
                 } else {
                     Err(lookahead.error())
                 }
             } else if lookahead.peek(Token![unsafe]) {
                 ahead.parse::<Token![unsafe]>()?;
                 let lookahead = ahead.lookahead1();
                 if lookahead.peek(Token![trait])
                     || lookahead.peek(Token![auto]) && ahead.peek2(Token![trait])
                 {
                     input.parse().map(Item::Trait)
                 } else if lookahead.peek(Token![impl]) {
-                    input.parse().map(Item::Impl)
-                } else if lookahead.peek(Token![async])
-                    || lookahead.peek(Token![extern])
-                    || lookahead.peek(Token![fn])
-                {
-                    input.parse().map(Item::Fn)
+                    let allow_const_impl = true;
+                    if let Some(item) = parse_impl(input, allow_const_impl)? {
+                        Ok(Item::Impl(item))
+                    } else {
+                        Ok(Item::Verbatim(verbatim::between(begin, input)))
+                    }
                 } else {
                     Err(lookahead.error())
                 }
-            } else if lookahead.peek(Token![async]) || lookahead.peek(Token![fn]) {
-                input.parse().map(Item::Fn)
             } else if lookahead.peek(Token![mod]) {
                 input.parse().map(Item::Mod)
             } else if lookahead.peek(Token![type]) {
-                input.parse().map(Item::Type)
+                parse_item_type(begin, input)
             } else if lookahead.peek(existential) {
                 input.call(item_existential).map(Item::Verbatim)
             } else if lookahead.peek(Token![struct]) {
                 input.parse().map(Item::Struct)
             } else if lookahead.peek(Token![enum]) {
                 input.parse().map(Item::Enum)
             } else if lookahead.peek(Token![union]) && ahead.peek2(Ident) {
                 input.parse().map(Item::Union)
             } else if lookahead.peek(Token![trait]) {
                 input.call(parse_trait_or_trait_alias)
             } else if lookahead.peek(Token![auto]) && ahead.peek2(Token![trait]) {
                 input.parse().map(Item::Trait)
             } else if lookahead.peek(Token![impl])
                 || lookahead.peek(Token![default]) && !ahead.peek2(Token![!])
             {
-                input.parse().map(Item::Impl)
+                let allow_const_impl = true;
+                if let Some(item) = parse_impl(input, allow_const_impl)? {
+                    Ok(Item::Impl(item))
+                } else {
+                    Ok(Item::Verbatim(verbatim::between(begin, input)))
+                }
             } else if lookahead.peek(Token![macro]) {
                 input.parse().map(Item::Macro2)
             } else if vis.is_inherited()
                 && (lookahead.peek(Ident)
                     || lookahead.peek(Token![self])
                     || lookahead.peek(Token![super])
-                    || lookahead.peek(Token![extern])
                     || lookahead.peek(Token![crate])
                     || lookahead.peek(Token![::]))
             {
                 input.parse().map(Item::Macro)
             } else {
                 Err(lookahead.error())
             }?;
 
-            {
-                let item_attrs = match &mut item {
-                    Item::ExternCrate(item) => &mut item.attrs,
-                    Item::Use(item) => &mut item.attrs,
-                    Item::Static(item) => &mut item.attrs,
-                    Item::Const(item) => &mut item.attrs,
-                    Item::Fn(item) => &mut item.attrs,
-                    Item::Mod(item) => &mut item.attrs,
-                    Item::ForeignMod(item) => &mut item.attrs,
-                    Item::Type(item) => &mut item.attrs,
-                    Item::Struct(item) => &mut item.attrs,
-                    Item::Enum(item) => &mut item.attrs,
-                    Item::Union(item) => &mut item.attrs,
-                    Item::Trait(item) => &mut item.attrs,
-                    Item::TraitAlias(item) => &mut item.attrs,
-                    Item::Impl(item) => &mut item.attrs,
-                    Item::Macro(item) => &mut item.attrs,
-                    Item::Macro2(item) => &mut item.attrs,
-                    Item::Verbatim(_) => return Ok(item),
-                    Item::__Nonexhaustive => unreachable!(),
-                };
-                attrs.extend(item_attrs.drain(..));
-                *item_attrs = attrs;
+            attrs.extend(item.replace_attrs(Vec::new()));
+            item.replace_attrs(attrs);
+            Ok(item)
+        }
+    }
+
+    struct FlexibleItemType {
+        vis: Visibility,
+        defaultness: Option<Token![default]>,
+        type_token: Token![type],
+        ident: Ident,
+        generics: Generics,
+        colon_token: Option<Token![:]>,
+        bounds: Punctuated<TypeParamBound, Token![+]>,
+        ty: Option<(Token![=], Type)>,
+        semi_token: Token![;],
+    }
+
+    impl Parse for FlexibleItemType {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let vis: Visibility = input.parse()?;
+            let defaultness: Option<Token![default]> = input.parse()?;
+            let type_token: Token![type] = input.parse()?;
+            let ident: Ident = input.parse()?;
+            let mut generics: Generics = input.parse()?;
+            let colon_token: Option<Token![:]> = input.parse()?;
+            let mut bounds = Punctuated::new();
+            if colon_token.is_some() {
+                loop {
+                    bounds.push_value(input.parse::<TypeParamBound>()?);
+                    if input.peek(Token![where]) || input.peek(Token![=]) || input.peek(Token![;]) {
+                        break;
+                    }
+                    bounds.push_punct(input.parse::<Token![+]>()?);
+                    if input.peek(Token![where]) || input.peek(Token![=]) || input.peek(Token![;]) {
+                        break;
+                    }
+                }
             }
+            generics.where_clause = input.parse()?;
+            let ty = if let Some(eq_token) = input.parse()? {
+                Some((eq_token, input.parse::<Type>()?))
+            } else {
+                None
+            };
+            let semi_token: Token![;] = input.parse()?;
 
-            Ok(item)
+            Ok(FlexibleItemType {
+                vis,
+                defaultness,
+                type_token,
+                ident,
+                generics,
+                colon_token,
+                bounds,
+                ty,
+                semi_token,
+            })
         }
     }
 
     impl Parse for ItemMacro {
         fn parse(input: ParseStream) -> Result<Self> {
             let attrs = input.call(Attribute::parse_outer)?;
             let path = input.call(Path::parse_mod_style)?;
             let bang_token: Token![!] = input.parse()?;
@@ -1305,17 +1192,16 @@ pub mod parsing {
 
     impl Parse for UseTree {
         fn parse(input: ParseStream) -> Result<UseTree> {
             let lookahead = input.lookahead1();
             if lookahead.peek(Ident)
                 || lookahead.peek(Token![self])
                 || lookahead.peek(Token![super])
                 || lookahead.peek(Token![crate])
-                || lookahead.peek(Token![extern])
             {
                 let ident = input.call(Ident::parse_any)?;
                 if input.peek(Token![::]) {
                     Ok(UseTree::Path(UsePath {
                         ident,
                         colon2_token: input.parse()?,
                         tree: Box::new(input.parse()?),
                     }))
@@ -1387,77 +1273,134 @@ pub mod parsing {
                 ty: input.parse()?,
                 eq_token: input.parse()?,
                 expr: input.parse()?,
                 semi_token: input.parse()?,
             })
         }
     }
 
+    fn pop_variadic(args: &mut Punctuated<FnArg, Token![,]>) -> Option<Variadic> {
+        let trailing_punct = args.trailing_punct();
+
+        let last = match args.last_mut()? {
+            FnArg::Typed(last) => last,
+            _ => return None,
+        };
+
+        let ty = match last.ty.as_ref() {
+            Type::Verbatim(ty) => ty,
+            _ => return None,
+        };
+
+        let mut variadic = Variadic {
+            attrs: Vec::new(),
+            dots: parse2(ty.clone()).ok()?,
+        };
+
+        if let Pat::Verbatim(pat) = last.pat.as_ref() {
+            if pat.to_string() == "..." && !trailing_punct {
+                variadic.attrs = mem::replace(&mut last.attrs, Vec::new());
+                args.pop();
+            }
+        }
+
+        Some(variadic)
+    }
+
+    fn variadic_to_tokens(dots: &Token![...]) -> TokenStream {
+        TokenStream::from_iter(vec![
+            TokenTree::Punct({
+                let mut dot = Punct::new('.', Spacing::Joint);
+                dot.set_span(dots.spans[0]);
+                dot
+            }),
+            TokenTree::Punct({
+                let mut dot = Punct::new('.', Spacing::Joint);
+                dot.set_span(dots.spans[1]);
+                dot
+            }),
+            TokenTree::Punct({
+                let mut dot = Punct::new('.', Spacing::Alone);
+                dot.set_span(dots.spans[2]);
+                dot
+            }),
+        ])
+    }
+
+    fn peek_signature(input: ParseStream) -> bool {
+        let fork = input.fork();
+        fork.parse::<Option<Token![const]>>().is_ok()
+            && fork.parse::<Option<Token![async]>>().is_ok()
+            && fork.parse::<Option<Token![unsafe]>>().is_ok()
+            && fork.parse::<Option<Abi>>().is_ok()
+            && fork.peek(Token![fn])
+    }
+
+    fn parse_signature(input: ParseStream) -> Result<Signature> {
+        let constness: Option<Token![const]> = input.parse()?;
+        let asyncness: Option<Token![async]> = input.parse()?;
+        let unsafety: Option<Token![unsafe]> = input.parse()?;
+        let abi: Option<Abi> = input.parse()?;
+        let fn_token: Token![fn] = input.parse()?;
+        let ident: Ident = input.parse()?;
+        let generics: Generics = input.parse()?;
+
+        let content;
+        let paren_token = parenthesized!(content in input);
+        let mut inputs = parse_fn_args(&content)?;
+        let variadic = pop_variadic(&mut inputs);
+
+        let output: ReturnType = input.parse()?;
+        let where_clause: Option<WhereClause> = input.parse()?;
+
+        Ok(Signature {
+            constness,
+            asyncness,
+            unsafety,
+            abi,
+            fn_token,
+            ident,
+            paren_token,
+            inputs,
+            output,
+            variadic,
+            generics: Generics {
+                where_clause,
+                ..generics
+            },
+        })
+    }
+
     impl Parse for ItemFn {
         fn parse(input: ParseStream) -> Result<Self> {
             let outer_attrs = input.call(Attribute::parse_outer)?;
             let vis: Visibility = input.parse()?;
-            let constness: Option<Token![const]> = input.parse()?;
-            let asyncness: Option<Token![async]> = input.parse()?;
-            let unsafety: Option<Token![unsafe]> = input.parse()?;
-            let abi: Option<Abi> = input.parse()?;
-            let fn_token: Token![fn] = input.parse()?;
-            let ident: Ident = input.parse()?;
-            let generics: Generics = input.parse()?;
-
-            let content;
-            let paren_token = parenthesized!(content in input);
-            let inputs = content.parse_terminated(FnArg::parse)?;
-            let variadic = inputs.last().as_ref().and_then(get_variadic);
-
-            fn get_variadic(input: &&FnArg) -> Option<Variadic> {
-                if let FnArg::Typed(PatType { ty, .. }) = input {
-                    if let Type::Verbatim(tokens) = &**ty {
-                        if let Ok(dots) = parse2(tokens.clone()) {
-                            return Some(Variadic {
-                                attrs: Vec::new(),
-                                dots,
-                            });
-                        }
-                    }
-                }
-                None
-            }
+            let sig = parse_signature(input)?;
+            parse_rest_of_fn(input, outer_attrs, vis, sig)
+        }
+    }
 
-            let output: ReturnType = input.parse()?;
-            let where_clause: Option<WhereClause> = input.parse()?;
-
-            let content;
-            let brace_token = braced!(content in input);
-            let inner_attrs = content.call(Attribute::parse_inner)?;
-            let stmts = content.call(Block::parse_within)?;
+    fn parse_rest_of_fn(
+        input: ParseStream,
+        outer_attrs: Vec<Attribute>,
+        vis: Visibility,
+        sig: Signature,
+    ) -> Result<ItemFn> {
+        let content;
+        let brace_token = braced!(content in input);
+        let inner_attrs = content.call(Attribute::parse_inner)?;
+        let stmts = content.call(Block::parse_within)?;
 
-            Ok(ItemFn {
-                attrs: private::attrs(outer_attrs, inner_attrs),
-                vis,
-                sig: Signature {
-                    constness,
-                    asyncness,
-                    unsafety,
-                    abi,
-                    fn_token,
-                    ident,
-                    paren_token,
-                    inputs,
-                    output,
-                    variadic,
-                    generics: Generics {
-                        where_clause,
-                        ..generics
-                    },
-                },
-                block: Box::new(Block { brace_token, stmts }),
-            })
-        }
+        Ok(ItemFn {
+            attrs: private::attrs(outer_attrs, inner_attrs),
+            vis,
+            sig,
+            block: Box::new(Block { brace_token, stmts }),
+        })
     }
 
     impl Parse for FnArg {
         fn parse(input: ParseStream) -> Result<Self> {
             let attrs = input.call(Attribute::parse_outer)?;
 
             let ahead = input.fork();
             if let Ok(mut receiver) = ahead.parse::<Receiver>() {
@@ -1486,36 +1429,89 @@ pub mod parsing {
                     }
                 },
                 mutability: input.parse()?,
                 self_token: input.parse()?,
             })
         }
     }
 
+    fn parse_fn_args(input: ParseStream) -> Result<Punctuated<FnArg, Token![,]>> {
+        let mut args = Punctuated::new();
+        let mut has_receiver = false;
+
+        while !input.is_empty() {
+            let attrs = input.call(Attribute::parse_outer)?;
+
+            let arg = if let Some(dots) = input.parse::<Option<Token![...]>>()? {
+                FnArg::Typed(PatType {
+                    attrs,
+                    pat: Box::new(Pat::Verbatim(variadic_to_tokens(&dots))),
+                    colon_token: Token![:](dots.spans[0]),
+                    ty: Box::new(Type::Verbatim(variadic_to_tokens(&dots))),
+                })
+            } else {
+                let mut arg: FnArg = input.parse()?;
+                match &mut arg {
+                    FnArg::Receiver(receiver) if has_receiver => {
+                        return Err(Error::new(
+                            receiver.self_token.span,
+                            "unexpected second method receiver",
+                        ));
+                    }
+                    FnArg::Receiver(receiver) if !args.is_empty() => {
+                        return Err(Error::new(
+                            receiver.self_token.span,
+                            "unexpected method receiver",
+                        ));
+                    }
+                    FnArg::Receiver(receiver) => {
+                        has_receiver = true;
+                        receiver.attrs = attrs;
+                    }
+                    FnArg::Typed(arg) => arg.attrs = attrs,
+                }
+                arg
+            };
+            args.push_value(arg);
+
+            if input.is_empty() {
+                break;
+            }
+
+            let comma: Token![,] = input.parse()?;
+            args.push_punct(comma);
+        }
+
+        Ok(args)
+    }
+
     fn fn_arg_typed(input: ParseStream) -> Result<PatType> {
+        // Hack to parse pre-2018 syntax in
+        // test/ui/rfc-2565-param-attrs/param-attrs-pretty.rs
+        // because the rest of the test case is valuable.
+        if input.peek(Ident) && input.peek2(Token![<]) {
+            let span = input.fork().parse::<Ident>()?.span();
+            return Ok(PatType {
+                attrs: Vec::new(),
+                pat: Box::new(Pat::Wild(PatWild {
+                    attrs: Vec::new(),
+                    underscore_token: Token![_](span),
+                })),
+                colon_token: Token![:](span),
+                ty: input.parse()?,
+            });
+        }
+
         Ok(PatType {
             attrs: Vec::new(),
-            pat: input.parse()?,
+            pat: Box::new(pat::parsing::multi_pat(input)?),
             colon_token: input.parse()?,
             ty: Box::new(match input.parse::<Option<Token![...]>>()? {
-                Some(dot3) => {
-                    let args = vec![
-                        TokenTree::Punct(Punct::new('.', Spacing::Joint)),
-                        TokenTree::Punct(Punct::new('.', Spacing::Joint)),
-                        TokenTree::Punct(Punct::new('.', Spacing::Alone)),
-                    ];
-                    let tokens = TokenStream::from_iter(args.into_iter().zip(&dot3.spans).map(
-                        |(mut arg, span)| {
-                            arg.set_span(*span);
-                            arg
-                        },
-                    ));
-                    Type::Verbatim(tokens)
-                }
+                Some(dot3) => Type::Verbatim(variadic_to_tokens(&dot3)),
                 None => input.parse()?,
             }),
         })
     }
 
     impl Parse for ItemMod {
         fn parse(input: ParseStream) -> Result<Self> {
             let outer_attrs = input.call(Attribute::parse_outer)?;
@@ -1576,109 +1572,103 @@ pub mod parsing {
                 brace_token,
                 items,
             })
         }
     }
 
     impl Parse for ForeignItem {
         fn parse(input: ParseStream) -> Result<Self> {
+            let begin = input.fork();
             let mut attrs = input.call(Attribute::parse_outer)?;
             let ahead = input.fork();
             let vis: Visibility = ahead.parse()?;
 
             let lookahead = ahead.lookahead1();
-            let mut item = if lookahead.peek(Token![fn]) {
-                input.parse().map(ForeignItem::Fn)
+            let mut item = if lookahead.peek(Token![fn]) || peek_signature(&ahead) {
+                let vis: Visibility = input.parse()?;
+                let sig = parse_signature(input)?;
+                if input.peek(token::Brace) {
+                    let content;
+                    braced!(content in input);
+                    content.call(Attribute::parse_inner)?;
+                    content.call(Block::parse_within)?;
+
+                    Ok(ForeignItem::Verbatim(verbatim::between(begin, input)))
+                } else {
+                    Ok(ForeignItem::Fn(ForeignItemFn {
+                        attrs: Vec::new(),
+                        vis,
+                        sig,
+                        semi_token: input.parse()?,
+                    }))
+                }
             } else if lookahead.peek(Token![static]) {
-                input.parse().map(ForeignItem::Static)
+                let vis = input.parse()?;
+                let static_token = input.parse()?;
+                let mutability = input.parse()?;
+                let ident = input.parse()?;
+                let colon_token = input.parse()?;
+                let ty = input.parse()?;
+                if input.peek(Token![=]) {
+                    input.parse::<Token![=]>()?;
+                    input.parse::<Expr>()?;
+                    input.parse::<Token![;]>()?;
+                    Ok(ForeignItem::Verbatim(verbatim::between(begin, input)))
+                } else {
+                    Ok(ForeignItem::Static(ForeignItemStatic {
+                        attrs: Vec::new(),
+                        vis,
+                        static_token,
+                        mutability,
+                        ident,
+                        colon_token,
+                        ty,
+                        semi_token: input.parse()?,
+                    }))
+                }
             } else if lookahead.peek(Token![type]) {
-                input.parse().map(ForeignItem::Type)
+                parse_foreign_item_type(begin, input)
             } else if vis.is_inherited()
                 && (lookahead.peek(Ident)
                     || lookahead.peek(Token![self])
                     || lookahead.peek(Token![super])
-                    || lookahead.peek(Token![extern])
                     || lookahead.peek(Token![crate])
                     || lookahead.peek(Token![::]))
             {
                 input.parse().map(ForeignItem::Macro)
             } else {
                 Err(lookahead.error())
             }?;
 
-            {
-                let item_attrs = match &mut item {
-                    ForeignItem::Fn(item) => &mut item.attrs,
-                    ForeignItem::Static(item) => &mut item.attrs,
-                    ForeignItem::Type(item) => &mut item.attrs,
-                    ForeignItem::Macro(item) => &mut item.attrs,
-                    ForeignItem::Verbatim(_) | ForeignItem::__Nonexhaustive => unreachable!(),
-                };
-                attrs.extend(item_attrs.drain(..));
-                *item_attrs = attrs;
-            }
+            let item_attrs = match &mut item {
+                ForeignItem::Fn(item) => &mut item.attrs,
+                ForeignItem::Static(item) => &mut item.attrs,
+                ForeignItem::Type(item) => &mut item.attrs,
+                ForeignItem::Macro(item) => &mut item.attrs,
+                ForeignItem::Verbatim(_) => return Ok(item),
+                ForeignItem::__Nonexhaustive => unreachable!(),
+            };
+            attrs.extend(item_attrs.drain(..));
+            *item_attrs = attrs;
 
             Ok(item)
         }
     }
 
     impl Parse for ForeignItemFn {
         fn parse(input: ParseStream) -> Result<Self> {
             let attrs = input.call(Attribute::parse_outer)?;
             let vis: Visibility = input.parse()?;
-            let fn_token: Token![fn] = input.parse()?;
-            let ident: Ident = input.parse()?;
-            let generics: Generics = input.parse()?;
-
-            let content;
-            let paren_token = parenthesized!(content in input);
-            let mut inputs = Punctuated::new();
-            let mut variadic = None;
-            while !content.is_empty() {
-                let attrs = content.call(Attribute::parse_outer)?;
-
-                if let Some(dots) = content.parse()? {
-                    variadic = Some(Variadic { attrs, dots });
-                    break;
-                }
-
-                let mut arg = content.call(fn_arg_typed)?;
-                arg.attrs = attrs;
-                inputs.push_value(FnArg::Typed(arg));
-                if content.is_empty() {
-                    break;
-                }
-
-                inputs.push_punct(content.parse()?);
-            }
-
-            let output: ReturnType = input.parse()?;
-            let where_clause: Option<WhereClause> = input.parse()?;
+            let sig = parse_signature(input)?;
             let semi_token: Token![;] = input.parse()?;
-
             Ok(ForeignItemFn {
                 attrs,
                 vis,
-                sig: Signature {
-                    constness: None,
-                    asyncness: None,
-                    unsafety: None,
-                    abi: None,
-                    fn_token,
-                    ident,
-                    paren_token,
-                    inputs,
-                    output,
-                    variadic,
-                    generics: Generics {
-                        where_clause,
-                        ..generics
-                    },
-                },
+                sig,
                 semi_token,
             })
         }
     }
 
     impl Parse for ForeignItemStatic {
         fn parse(input: ParseStream) -> Result<Self> {
             Ok(ForeignItemStatic {
@@ -1701,16 +1691,47 @@ pub mod parsing {
                 vis: input.parse()?,
                 type_token: input.parse()?,
                 ident: input.parse()?,
                 semi_token: input.parse()?,
             })
         }
     }
 
+    fn parse_foreign_item_type(begin: ParseBuffer, input: ParseStream) -> Result<ForeignItem> {
+        let FlexibleItemType {
+            vis,
+            defaultness,
+            type_token,
+            ident,
+            generics,
+            colon_token,
+            bounds: _,
+            ty,
+            semi_token,
+        } = input.parse()?;
+
+        if defaultness.is_some()
+            || generics.lt_token.is_some()
+            || generics.where_clause.is_some()
+            || colon_token.is_some()
+            || ty.is_some()
+        {
+            Ok(ForeignItem::Verbatim(verbatim::between(begin, input)))
+        } else {
+            Ok(ForeignItem::Type(ForeignItemType {
+                attrs: Vec::new(),
+                vis,
+                type_token,
+                ident,
+                semi_token,
+            }))
+        }
+    }
+
     impl Parse for ForeignItemMacro {
         fn parse(input: ParseStream) -> Result<Self> {
             let attrs = input.call(Attribute::parse_outer)?;
             let mac: Macro = input.parse()?;
             let semi_token: Option<Token![;]> = if mac.delimiter.is_brace() {
                 None
             } else {
                 Some(input.parse()?)
@@ -1737,16 +1758,46 @@ pub mod parsing {
                 },
                 eq_token: input.parse()?,
                 ty: input.parse()?,
                 semi_token: input.parse()?,
             })
         }
     }
 
+    fn parse_item_type(begin: ParseBuffer, input: ParseStream) -> Result<Item> {
+        let FlexibleItemType {
+            vis,
+            defaultness,
+            type_token,
+            ident,
+            generics,
+            colon_token,
+            bounds: _,
+            ty,
+            semi_token,
+        } = input.parse()?;
+
+        if defaultness.is_some() || colon_token.is_some() || ty.is_none() {
+            Ok(Item::Verbatim(verbatim::between(begin, input)))
+        } else {
+            let (eq_token, ty) = ty.unwrap();
+            Ok(Item::Type(ItemType {
+                attrs: Vec::new(),
+                vis,
+                type_token,
+                ident,
+                generics,
+                eq_token,
+                ty: Box::new(ty),
+                semi_token,
+            }))
+        }
+    }
+
     #[cfg(not(feature = "printing"))]
     fn item_existential(input: ParseStream) -> Result<TokenStream> {
         Err(input.error("existential type is not supported"))
     }
 
     #[cfg(feature = "printing")]
     fn item_existential(input: ParseStream) -> Result<TokenStream> {
         use crate::attr::FilterAttrs;
@@ -1882,39 +1933,39 @@ pub mod parsing {
                 .map(Item::TraitAlias)
         } else {
             Err(lookahead.error())
         }
     }
 
     impl Parse for ItemTrait {
         fn parse(input: ParseStream) -> Result<Self> {
-            let attrs = input.call(Attribute::parse_outer)?;
+            let outer_attrs = input.call(Attribute::parse_outer)?;
             let vis: Visibility = input.parse()?;
             let unsafety: Option<Token![unsafe]> = input.parse()?;
             let auto_token: Option<Token![auto]> = input.parse()?;
             let trait_token: Token![trait] = input.parse()?;
             let ident: Ident = input.parse()?;
             let generics: Generics = input.parse()?;
             parse_rest_of_trait(
                 input,
-                attrs,
+                outer_attrs,
                 vis,
                 unsafety,
                 auto_token,
                 trait_token,
                 ident,
                 generics,
             )
         }
     }
 
     fn parse_rest_of_trait(
         input: ParseStream,
-        attrs: Vec<Attribute>,
+        outer_attrs: Vec<Attribute>,
         vis: Visibility,
         unsafety: Option<Token![unsafe]>,
         auto_token: Option<Token![auto]>,
         trait_token: Token![trait],
         ident: Ident,
         mut generics: Generics,
     ) -> Result<ItemTrait> {
         let colon_token: Option<Token![:]> = input.parse()?;
@@ -1932,23 +1983,24 @@ pub mod parsing {
                 }
             }
         }
 
         generics.where_clause = input.parse()?;
 
         let content;
         let brace_token = braced!(content in input);
+        let inner_attrs = content.call(Attribute::parse_inner)?;
         let mut items = Vec::new();
         while !content.is_empty() {
             items.push(content.parse()?);
         }
 
         Ok(ItemTrait {
-            attrs,
+            attrs: private::attrs(outer_attrs, inner_attrs),
             vis,
             unsafety,
             auto_token,
             trait_token,
             ident,
             generics,
             colon_token,
             supertraits,
@@ -2009,76 +2061,83 @@ pub mod parsing {
             eq_token,
             bounds,
             semi_token,
         })
     }
 
     impl Parse for TraitItem {
         fn parse(input: ParseStream) -> Result<Self> {
+            let begin = input.fork();
             let mut attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let defaultness: Option<Token![default]> = input.parse()?;
             let ahead = input.fork();
 
             let lookahead = ahead.lookahead1();
-            let mut item = if lookahead.peek(Token![const]) {
+            let mut item = if lookahead.peek(Token![fn]) || peek_signature(&ahead) {
+                input.parse().map(TraitItem::Method)
+            } else if lookahead.peek(Token![const]) {
                 ahead.parse::<Token![const]>()?;
                 let lookahead = ahead.lookahead1();
-                if lookahead.peek(Ident) {
+                if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
                     input.parse().map(TraitItem::Const)
                 } else if lookahead.peek(Token![async])
                     || lookahead.peek(Token![unsafe])
                     || lookahead.peek(Token![extern])
                     || lookahead.peek(Token![fn])
                 {
                     input.parse().map(TraitItem::Method)
                 } else {
                     Err(lookahead.error())
                 }
-            } else if lookahead.peek(Token![async])
-                || lookahead.peek(Token![unsafe])
-                || lookahead.peek(Token![extern])
-                || lookahead.peek(Token![fn])
-            {
-                input.parse().map(TraitItem::Method)
             } else if lookahead.peek(Token![type]) {
-                input.parse().map(TraitItem::Type)
+                parse_trait_item_type(begin.fork(), input)
             } else if lookahead.peek(Ident)
                 || lookahead.peek(Token![self])
                 || lookahead.peek(Token![super])
-                || lookahead.peek(Token![extern])
                 || lookahead.peek(Token![crate])
                 || lookahead.peek(Token![::])
             {
                 input.parse().map(TraitItem::Macro)
             } else {
                 Err(lookahead.error())
             }?;
 
-            {
-                let item_attrs = match &mut item {
-                    TraitItem::Const(item) => &mut item.attrs,
-                    TraitItem::Method(item) => &mut item.attrs,
-                    TraitItem::Type(item) => &mut item.attrs,
-                    TraitItem::Macro(item) => &mut item.attrs,
-                    TraitItem::Verbatim(_) | TraitItem::__Nonexhaustive => unreachable!(),
-                };
-                attrs.extend(item_attrs.drain(..));
-                *item_attrs = attrs;
+            match (vis, defaultness) {
+                (Visibility::Inherited, None) => {}
+                _ => return Ok(TraitItem::Verbatim(verbatim::between(begin, input))),
             }
 
+            let item_attrs = match &mut item {
+                TraitItem::Const(item) => &mut item.attrs,
+                TraitItem::Method(item) => &mut item.attrs,
+                TraitItem::Type(item) => &mut item.attrs,
+                TraitItem::Macro(item) => &mut item.attrs,
+                TraitItem::Verbatim(_) | TraitItem::__Nonexhaustive => unreachable!(),
+            };
+            attrs.extend(item_attrs.drain(..));
+            *item_attrs = attrs;
             Ok(item)
         }
     }
 
     impl Parse for TraitItemConst {
         fn parse(input: ParseStream) -> Result<Self> {
             Ok(TraitItemConst {
                 attrs: input.call(Attribute::parse_outer)?,
                 const_token: input.parse()?,
-                ident: input.parse()?,
+                ident: {
+                    let lookahead = input.lookahead1();
+                    if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                        input.call(Ident::parse_any)?
+                    } else {
+                        return Err(lookahead.error());
+                    }
+                },
                 colon_token: input.parse()?,
                 ty: input.parse()?,
                 default: {
                     if input.peek(Token![=]) {
                         let eq_token: Token![=] = input.parse()?;
                         let default: Expr = input.parse()?;
                         Some((eq_token, default))
                     } else {
@@ -2088,30 +2147,17 @@ pub mod parsing {
                 semi_token: input.parse()?,
             })
         }
     }
 
     impl Parse for TraitItemMethod {
         fn parse(input: ParseStream) -> Result<Self> {
             let outer_attrs = input.call(Attribute::parse_outer)?;
-            let constness: Option<Token![const]> = input.parse()?;
-            let asyncness: Option<Token![async]> = input.parse()?;
-            let unsafety: Option<Token![unsafe]> = input.parse()?;
-            let abi: Option<Abi> = input.parse()?;
-            let fn_token: Token![fn] = input.parse()?;
-            let ident: Ident = input.parse()?;
-            let generics: Generics = input.parse()?;
-
-            let content;
-            let paren_token = parenthesized!(content in input);
-            let inputs = content.parse_terminated(FnArg::parse)?;
-
-            let output: ReturnType = input.parse()?;
-            let where_clause: Option<WhereClause> = input.parse()?;
+            let sig = parse_signature(input)?;
 
             let lookahead = input.lookahead1();
             let (brace_token, inner_attrs, stmts, semi_token) = if lookahead.peek(token::Brace) {
                 let content;
                 let brace_token = braced!(content in input);
                 let inner_attrs = content.call(Attribute::parse_inner)?;
                 let stmts = content.call(Block::parse_within)?;
                 (Some(brace_token), inner_attrs, stmts, None)
@@ -2119,32 +2165,17 @@ pub mod parsing {
                 let semi_token: Token![;] = input.parse()?;
                 (None, Vec::new(), Vec::new(), Some(semi_token))
             } else {
                 return Err(lookahead.error());
             };
 
             Ok(TraitItemMethod {
                 attrs: private::attrs(outer_attrs, inner_attrs),
-                sig: Signature {
-                    constness,
-                    asyncness,
-                    unsafety,
-                    abi,
-                    fn_token,
-                    ident,
-                    paren_token,
-                    inputs,
-                    output,
-                    variadic: None,
-                    generics: Generics {
-                        where_clause,
-                        ..generics
-                    },
-                },
+                sig,
                 default: brace_token.map(|brace_token| Block { brace_token, stmts }),
                 semi_token,
             })
         }
     }
 
     impl Parse for TraitItemType {
         fn parse(input: ParseStream) -> Result<Self> {
@@ -2183,16 +2214,45 @@ pub mod parsing {
                 colon_token,
                 bounds,
                 default,
                 semi_token,
             })
         }
     }
 
+    fn parse_trait_item_type(begin: ParseBuffer, input: ParseStream) -> Result<TraitItem> {
+        let FlexibleItemType {
+            vis,
+            defaultness,
+            type_token,
+            ident,
+            generics,
+            colon_token,
+            bounds,
+            ty,
+            semi_token,
+        } = input.parse()?;
+
+        if defaultness.is_some() || vis.is_some() {
+            Ok(TraitItem::Verbatim(verbatim::between(begin, input)))
+        } else {
+            Ok(TraitItem::Type(TraitItemType {
+                attrs: Vec::new(),
+                type_token,
+                ident,
+                generics,
+                colon_token,
+                bounds,
+                default: ty,
+                semi_token,
+            }))
+        }
+    }
+
     impl Parse for TraitItemMacro {
         fn parse(input: ParseStream) -> Result<Self> {
             let attrs = input.call(Attribute::parse_outer)?;
             let mac: Macro = input.parse()?;
             let semi_token: Option<Token![;]> = if mac.delimiter.is_brace() {
                 None
             } else {
                 Some(input.parse()?)
@@ -2202,123 +2262,148 @@ pub mod parsing {
                 mac,
                 semi_token,
             })
         }
     }
 
     impl Parse for ItemImpl {
         fn parse(input: ParseStream) -> Result<Self> {
-            let outer_attrs = input.call(Attribute::parse_outer)?;
-            let defaultness: Option<Token![default]> = input.parse()?;
-            let unsafety: Option<Token![unsafe]> = input.parse()?;
-            let impl_token: Token![impl] = input.parse()?;
+            let allow_const_impl = false;
+            parse_impl(input, allow_const_impl).map(Option::unwrap)
+        }
+    }
+
+    fn parse_impl(input: ParseStream, allow_const_impl: bool) -> Result<Option<ItemImpl>> {
+        let outer_attrs = input.call(Attribute::parse_outer)?;
+        let defaultness: Option<Token![default]> = input.parse()?;
+        let unsafety: Option<Token![unsafe]> = input.parse()?;
+        let impl_token: Token![impl] = input.parse()?;
 
-            let has_generics = input.peek(Token![<])
-                && (input.peek2(Token![>])
-                    || input.peek2(Token![#])
-                    || (input.peek2(Ident) || input.peek2(Lifetime))
-                        && (input.peek3(Token![:])
-                            || input.peek3(Token![,])
-                            || input.peek3(Token![>])));
-            let generics: Generics = if has_generics {
-                input.parse()?
-            } else {
-                Generics::default()
-            };
+        let has_generics = input.peek(Token![<])
+            && (input.peek2(Token![>])
+                || input.peek2(Token![#])
+                || (input.peek2(Ident) || input.peek2(Lifetime))
+                    && (input.peek3(Token![:])
+                        || input.peek3(Token![,])
+                        || input.peek3(Token![>]))
+                || input.peek2(Token![const]));
+        let generics: Generics = if has_generics {
+            input.parse()?
+        } else {
+            Generics::default()
+        };
 
-            let trait_ = {
-                // TODO: optimize using advance_to
-                let ahead = input.fork();
-                if ahead.parse::<Option<Token![!]>>().is_ok()
-                    && ahead.parse::<Path>().is_ok()
-                    && ahead.parse::<Token![for]>().is_ok()
-                {
-                    let polarity: Option<Token![!]> = input.parse()?;
-                    let path: Path = input.parse()?;
-                    let for_token: Token![for] = input.parse()?;
-                    Some((polarity, path, for_token))
-                } else {
-                    None
-                }
-            };
-            let self_ty: Type = input.parse()?;
-            let where_clause: Option<WhereClause> = input.parse()?;
+        let is_const_impl = allow_const_impl
+            && (input.peek(Token![const]) || input.peek(Token![?]) && input.peek2(Token![const]));
+        if is_const_impl {
+            input.parse::<Option<Token![?]>>()?;
+            input.parse::<Token![const]>()?;
+        }
 
-            let content;
-            let brace_token = braced!(content in input);
-            let inner_attrs = content.call(Attribute::parse_inner)?;
+        let trait_ = (|| -> Option<_> {
+            let ahead = input.fork();
+            let polarity: Option<Token![!]> = ahead.parse().ok()?;
+            let mut path: Path = ahead.parse().ok()?;
+            if path.segments.last().unwrap().arguments.is_empty() && ahead.peek(token::Paren) {
+                let parenthesized = PathArguments::Parenthesized(ahead.parse().ok()?);
+                path.segments.last_mut().unwrap().arguments = parenthesized;
+            }
+            let for_token: Token![for] = ahead.parse().ok()?;
+            input.advance_to(&ahead);
+            Some((polarity, path, for_token))
+        })();
 
-            let mut items = Vec::new();
-            while !content.is_empty() {
-                items.push(content.parse()?);
-            }
+        let self_ty: Type = input.parse()?;
+        let where_clause: Option<WhereClause> = input.parse()?;
+
+        let content;
+        let brace_token = braced!(content in input);
+        let inner_attrs = content.call(Attribute::parse_inner)?;
 
-            Ok(ItemImpl {
+        let mut items = Vec::new();
+        while !content.is_empty() {
+            items.push(content.parse()?);
+        }
+
+        if is_const_impl {
+            Ok(None)
+        } else {
+            Ok(Some(ItemImpl {
                 attrs: private::attrs(outer_attrs, inner_attrs),
                 defaultness,
                 unsafety,
                 impl_token,
                 generics: Generics {
                     where_clause,
                     ..generics
                 },
                 trait_,
                 self_ty: Box::new(self_ty),
                 brace_token,
                 items,
-            })
+            }))
         }
     }
 
     impl Parse for ImplItem {
         fn parse(input: ParseStream) -> Result<Self> {
+            let begin = input.fork();
             let mut attrs = input.call(Attribute::parse_outer)?;
             let ahead = input.fork();
             let vis: Visibility = ahead.parse()?;
 
             let mut lookahead = ahead.lookahead1();
             let defaultness = if lookahead.peek(Token![default]) && !ahead.peek2(Token![!]) {
                 let defaultness: Token![default] = ahead.parse()?;
                 lookahead = ahead.lookahead1();
                 Some(defaultness)
             } else {
                 None
             };
 
-            let mut item = if lookahead.peek(Token![const]) {
-                ahead.parse::<Token![const]>()?;
+            let mut item = if lookahead.peek(Token![fn]) || peek_signature(&ahead) {
+                input.parse().map(ImplItem::Method)
+            } else if lookahead.peek(Token![const]) {
+                let const_token: Token![const] = ahead.parse()?;
                 let lookahead = ahead.lookahead1();
-                if lookahead.peek(Ident) {
-                    input.parse().map(ImplItem::Const)
-                } else if lookahead.peek(Token![unsafe])
-                    || lookahead.peek(Token![async])
-                    || lookahead.peek(Token![extern])
-                    || lookahead.peek(Token![fn])
-                {
-                    input.parse().map(ImplItem::Method)
+                if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                    input.advance_to(&ahead);
+                    let ident: Ident = input.call(Ident::parse_any)?;
+                    let colon_token: Token![:] = input.parse()?;
+                    let ty: Type = input.parse()?;
+                    if let Some(eq_token) = input.parse()? {
+                        return Ok(ImplItem::Const(ImplItemConst {
+                            attrs,
+                            vis,
+                            defaultness,
+                            const_token,
+                            ident,
+                            colon_token,
+                            ty,
+                            eq_token,
+                            expr: input.parse()?,
+                            semi_token: input.parse()?,
+                        }));
+                    } else {
+                        input.parse::<Token![;]>()?;
+                        return Ok(ImplItem::Verbatim(verbatim::between(begin, input)));
+                    }
                 } else {
                     Err(lookahead.error())
                 }
-            } else if lookahead.peek(Token![unsafe])
-                || lookahead.peek(Token![async])
-                || lookahead.peek(Token![extern])
-                || lookahead.peek(Token![fn])
-            {
-                input.parse().map(ImplItem::Method)
             } else if lookahead.peek(Token![type]) {
-                input.parse().map(ImplItem::Type)
+                parse_impl_item_type(begin, input)
             } else if vis.is_inherited() && defaultness.is_none() && lookahead.peek(existential) {
                 input.call(item_existential).map(ImplItem::Verbatim)
             } else if vis.is_inherited()
                 && defaultness.is_none()
                 && (lookahead.peek(Ident)
                     || lookahead.peek(Token![self])
                     || lookahead.peek(Token![super])
-                    || lookahead.peek(Token![extern])
                     || lookahead.peek(Token![crate])
                     || lookahead.peek(Token![::]))
             {
                 input.parse().map(ImplItem::Macro)
             } else {
                 Err(lookahead.error())
             }?;
 
@@ -2341,72 +2426,68 @@ pub mod parsing {
 
     impl Parse for ImplItemConst {
         fn parse(input: ParseStream) -> Result<Self> {
             Ok(ImplItemConst {
                 attrs: input.call(Attribute::parse_outer)?,
                 vis: input.parse()?,
                 defaultness: input.parse()?,
                 const_token: input.parse()?,
-                ident: input.parse()?,
+                ident: {
+                    let lookahead = input.lookahead1();
+                    if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                        input.call(Ident::parse_any)?
+                    } else {
+                        return Err(lookahead.error());
+                    }
+                },
                 colon_token: input.parse()?,
                 ty: input.parse()?,
                 eq_token: input.parse()?,
                 expr: input.parse()?,
                 semi_token: input.parse()?,
             })
         }
     }
 
     impl Parse for ImplItemMethod {
         fn parse(input: ParseStream) -> Result<Self> {
-            let outer_attrs = input.call(Attribute::parse_outer)?;
+            let mut attrs = input.call(Attribute::parse_outer)?;
             let vis: Visibility = input.parse()?;
             let defaultness: Option<Token![default]> = input.parse()?;
-            let constness: Option<Token![const]> = input.parse()?;
-            let asyncness: Option<Token![async]> = input.parse()?;
-            let unsafety: Option<Token![unsafe]> = input.parse()?;
-            let abi: Option<Abi> = input.parse()?;
-            let fn_token: Token![fn] = input.parse()?;
-            let ident: Ident = input.parse()?;
-            let generics: Generics = input.parse()?;
+            let sig = parse_signature(input)?;
 
-            let content;
-            let paren_token = parenthesized!(content in input);
-            let inputs = content.parse_terminated(FnArg::parse)?;
-
-            let output: ReturnType = input.parse()?;
-            let where_clause: Option<WhereClause> = input.parse()?;
-
-            let content;
-            let brace_token = braced!(content in input);
-            let inner_attrs = content.call(Attribute::parse_inner)?;
-            let stmts = content.call(Block::parse_within)?;
+            let block = if let Some(semi) = input.parse::<Option<Token![;]>>()? {
+                // Accept methods without a body in an impl block because
+                // rustc's *parser* does not reject them (the compilation error
+                // is emitted later than parsing) and it can be useful for macro
+                // DSLs.
+                let mut punct = Punct::new(';', Spacing::Alone);
+                punct.set_span(semi.span);
+                let tokens = TokenStream::from_iter(vec![TokenTree::Punct(punct)]);
+                Block {
+                    brace_token: Brace::default(),
+                    stmts: vec![Stmt::Item(Item::Verbatim(tokens))],
+                }
+            } else {
+                let content;
+                let brace_token = braced!(content in input);
+                attrs.extend(content.call(Attribute::parse_inner)?);
+                Block {
+                    brace_token,
+                    stmts: content.call(Block::parse_within)?,
+                }
+            };
 
             Ok(ImplItemMethod {
-                attrs: private::attrs(outer_attrs, inner_attrs),
+                attrs,
                 vis,
                 defaultness,
-                sig: Signature {
-                    constness,
-                    asyncness,
-                    unsafety,
-                    abi,
-                    fn_token,
-                    ident,
-                    paren_token,
-                    inputs,
-                    output,
-                    variadic: None,
-                    generics: Generics {
-                        where_clause,
-                        ..generics
-                    },
-                },
-                block: Block { brace_token, stmts },
+                sig,
+                block,
             })
         }
     }
 
     impl Parse for ImplItemType {
         fn parse(input: ParseStream) -> Result<Self> {
             Ok(ImplItemType {
                 attrs: input.call(Attribute::parse_outer)?,
@@ -2421,16 +2502,47 @@ pub mod parsing {
                 },
                 eq_token: input.parse()?,
                 ty: input.parse()?,
                 semi_token: input.parse()?,
             })
         }
     }
 
+    fn parse_impl_item_type(begin: ParseBuffer, input: ParseStream) -> Result<ImplItem> {
+        let FlexibleItemType {
+            vis,
+            defaultness,
+            type_token,
+            ident,
+            generics,
+            colon_token,
+            bounds: _,
+            ty,
+            semi_token,
+        } = input.parse()?;
+
+        if colon_token.is_some() || ty.is_none() {
+            Ok(ImplItem::Verbatim(verbatim::between(begin, input)))
+        } else {
+            let (eq_token, ty) = ty.unwrap();
+            Ok(ImplItem::Type(ImplItemType {
+                attrs: Vec::new(),
+                vis,
+                defaultness,
+                type_token,
+                ident,
+                generics,
+                eq_token,
+                ty,
+                semi_token,
+            }))
+        }
+    }
+
     impl Parse for ImplItemMacro {
         fn parse(input: ParseStream) -> Result<Self> {
             let attrs = input.call(Attribute::parse_outer)?;
             let mac: Macro = input.parse()?;
             let semi_token: Option<Token![;]> = if mac.delimiter.is_brace() {
                 None
             } else {
                 Some(input.parse()?)
@@ -2466,16 +2578,17 @@ pub mod parsing {
 mod printing {
     use super::*;
 
     use proc_macro2::TokenStream;
     use quote::{ToTokens, TokenStreamExt};
 
     use crate::attr::FilterAttrs;
     use crate::print::TokensOrDefault;
+    use crate::punctuated::Pair;
 
     impl ToTokens for ItemExternCrate {
         fn to_tokens(&self, tokens: &mut TokenStream) {
             tokens.append_all(self.attrs.outer());
             self.vis.to_tokens(tokens);
             self.extern_token.to_tokens(tokens);
             self.crate_token.to_tokens(tokens);
             self.ident.to_tokens(tokens);
@@ -2830,16 +2943,24 @@ mod printing {
     }
 
     impl ToTokens for ImplItemMethod {
         fn to_tokens(&self, tokens: &mut TokenStream) {
             tokens.append_all(self.attrs.outer());
             self.vis.to_tokens(tokens);
             self.defaultness.to_tokens(tokens);
             self.sig.to_tokens(tokens);
+            if self.block.stmts.len() == 1 {
+                if let Stmt::Item(Item::Verbatim(verbatim)) = &self.block.stmts[0] {
+                    if verbatim.to_string() == ";" {
+                        verbatim.to_tokens(tokens);
+                        return;
+                    }
+                }
+            }
             self.block.brace_token.surround(tokens, |tokens| {
                 tokens.append_all(self.attrs.inner());
                 tokens.append_all(&self.block.stmts);
             });
         }
     }
 
     impl ToTokens for ImplItemType {
@@ -2900,31 +3021,71 @@ mod printing {
     impl ToTokens for ForeignItemMacro {
         fn to_tokens(&self, tokens: &mut TokenStream) {
             tokens.append_all(self.attrs.outer());
             self.mac.to_tokens(tokens);
             self.semi_token.to_tokens(tokens);
         }
     }
 
+    fn maybe_variadic_to_tokens(arg: &FnArg, tokens: &mut TokenStream) -> bool {
+        let arg = match arg {
+            FnArg::Typed(arg) => arg,
+            FnArg::Receiver(receiver) => {
+                receiver.to_tokens(tokens);
+                return false;
+            }
+        };
+
+        match arg.ty.as_ref() {
+            Type::Verbatim(ty) if ty.to_string() == "..." => {
+                match arg.pat.as_ref() {
+                    Pat::Verbatim(pat) if pat.to_string() == "..." => {
+                        tokens.append_all(arg.attrs.outer());
+                        pat.to_tokens(tokens);
+                    }
+                    _ => arg.to_tokens(tokens),
+                }
+                true
+            }
+            _ => {
+                arg.to_tokens(tokens);
+                false
+            }
+        }
+    }
+
     impl ToTokens for Signature {
         fn to_tokens(&self, tokens: &mut TokenStream) {
             self.constness.to_tokens(tokens);
             self.asyncness.to_tokens(tokens);
             self.unsafety.to_tokens(tokens);
             self.abi.to_tokens(tokens);
             self.fn_token.to_tokens(tokens);
             self.ident.to_tokens(tokens);
             self.generics.to_tokens(tokens);
             self.paren_token.surround(tokens, |tokens| {
-                self.inputs.to_tokens(tokens);
-                if self.variadic.is_some() && !self.inputs.empty_or_trailing() {
-                    <Token![,]>::default().to_tokens(tokens);
+                let mut last_is_variadic = false;
+                for input in self.inputs.pairs() {
+                    match input {
+                        Pair::Punctuated(input, comma) => {
+                            maybe_variadic_to_tokens(input, tokens);
+                            comma.to_tokens(tokens);
+                        }
+                        Pair::End(input) => {
+                            last_is_variadic = maybe_variadic_to_tokens(input, tokens);
+                        }
+                    }
                 }
-                self.variadic.to_tokens(tokens);
+                if self.variadic.is_some() && !last_is_variadic {
+                    if !self.inputs.empty_or_trailing() {
+                        <Token![,]>::default().to_tokens(tokens);
+                    }
+                    self.variadic.to_tokens(tokens);
+                }
             });
             self.output.to_tokens(tokens);
             self.generics.where_clause.to_tokens(tokens);
         }
     }
 
     impl ToTokens for Receiver {
         fn to_tokens(&self, tokens: &mut TokenStream) {
diff --git a/third_party/rust/syn/src/lib.rs b/third_party/rust/syn/src/lib.rs
--- a/third_party/rust/syn/src/lib.rs
+++ b/third_party/rust/syn/src/lib.rs
@@ -1,8 +1,16 @@
+//! [![github]](https://github.com/dtolnay/syn)&ensp;[![crates-io]](https://crates.io/crates/syn)&ensp;[![docs-rs]](https://docs.rs/syn)
+//!
+//! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github
+//! [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rust
+//! [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logoColor=white&logo=data:image/svg+xml;base64,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
+//!
+//! <br>
+//!
 //! Syn is a parsing library for parsing a stream of Rust tokens into a syntax
 //! tree of Rust source code.
 //!
 //! Currently this library is geared toward use in Rust procedural macros, but
 //! contains some APIs that may be useful more generally.
 //!
 //! - **Data structures** — Syn provides a complete syntax tree that can
 //!   represent any valid Rust source code. The syntax tree is rooted at
@@ -57,18 +65,18 @@
 //! syn = "1.0"
 //! quote = "1.0"
 //!
 //! [lib]
 //! proc-macro = true
 //! ```
 //!
 //! ```
-//! extern crate proc_macro;
-//!
+//! # extern crate proc_macro;
+//! #
 //! use proc_macro::TokenStream;
 //! use quote::quote;
 //! use syn::{parse_macro_input, DeriveInput};
 //!
 //! # const IGNORE_TOKENS: &str = stringify! {
 //! #[proc_macro_derive(MyMacro)]
 //! # };
 //! pub fn my_macro(input: TokenStream) -> TokenStream {
@@ -237,59 +245,71 @@
 //! - **`clone-impls`** *(enabled by default)* — Clone impls for all syntax tree
 //!   types.
 //! - **`extra-traits`** — Debug, Eq, PartialEq, Hash impls for all syntax tree
 //!   types.
 //! - **`proc-macro`** *(enabled by default)* — Runtime dependency on the
 //!   dynamic library libproc_macro from rustc toolchain.
 
 // Syn types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/syn/1.0.5")]
+#![doc(html_root_url = "https://docs.rs/syn/1.0.40")]
 #![deny(clippy::all, clippy::pedantic)]
 // Ignored clippy lints.
 #![allow(
-    clippy::block_in_if_condition_stmt,
+    clippy::blocks_in_if_conditions,
     clippy::cognitive_complexity,
     clippy::doc_markdown,
     clippy::eval_order_dependence,
     clippy::inherent_to_string,
     clippy::large_enum_variant,
+    clippy::manual_non_exhaustive,
+    clippy::match_like_matches_macro,
+    clippy::match_on_vec_items,
+    clippy::needless_doctest_main,
     clippy::needless_pass_by_value,
     clippy::never_loop,
     clippy::suspicious_op_assign_impl,
     clippy::too_many_arguments,
-    clippy::trivially_copy_pass_by_ref
+    clippy::trivially_copy_pass_by_ref,
+    clippy::unnecessary_unwrap
 )]
 // Ignored clippy_pedantic lints.
 #![allow(
     clippy::cast_possible_truncation,
+    clippy::default_trait_access,
     clippy::empty_enum,
+    clippy::expl_impl_clone_on_copy,
     clippy::if_not_else,
     clippy::items_after_statements,
+    clippy::match_same_arms,
+    clippy::missing_errors_doc,
     clippy::module_name_repetitions,
+    clippy::must_use_candidate,
+    clippy::option_if_let_else,
     clippy::shadow_unrelated,
     clippy::similar_names,
     clippy::single_match_else,
+    clippy::too_many_lines,
     clippy::unseparated_literal_suffix,
     clippy::use_self,
-    clippy::used_underscore_binding
+    clippy::used_underscore_binding,
+    clippy::wildcard_imports
 )]
 
 #[cfg(all(
     not(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "wasi"))),
     feature = "proc-macro"
 ))]
 extern crate proc_macro;
 extern crate proc_macro2;
 extern crate unicode_xid;
 
 #[cfg(feature = "printing")]
 extern crate quote;
 
-#[cfg(any(feature = "full", feature = "derive"))]
 #[macro_use]
 mod macros;
 
 // Not public API.
 #[cfg(feature = "parsing")]
 #[doc(hidden)]
 #[macro_use]
 pub mod group;
@@ -302,17 +322,16 @@ pub use crate::ident::Ident;
 
 #[cfg(any(feature = "full", feature = "derive"))]
 mod attr;
 #[cfg(any(feature = "full", feature = "derive"))]
 pub use crate::attr::{
     AttrStyle, Attribute, AttributeArgs, Meta, MetaList, MetaNameValue, NestedMeta,
 };
 
-#[cfg(any(feature = "full", feature = "derive"))]
 mod bigint;
 
 #[cfg(any(feature = "full", feature = "derive"))]
 mod data;
 #[cfg(any(feature = "full", feature = "derive"))]
 pub use crate::data::{
     Field, Fields, FieldsNamed, FieldsUnnamed, Variant, VisCrate, VisPublic, VisRestricted,
     Visibility,
@@ -359,19 +378,17 @@ pub use crate::item::{
 #[cfg(feature = "full")]
 mod file;
 #[cfg(feature = "full")]
 pub use crate::file::File;
 
 mod lifetime;
 pub use crate::lifetime::Lifetime;
 
-#[cfg(any(feature = "full", feature = "derive"))]
 mod lit;
-#[cfg(any(feature = "full", feature = "derive"))]
 pub use crate::lit::{
     Lit, LitBool, LitByte, LitByteStr, LitChar, LitFloat, LitInt, LitStr, StrStyle,
 };
 
 #[cfg(any(feature = "full", feature = "derive"))]
 mod mac;
 #[cfg(any(feature = "full", feature = "derive"))]
 pub use crate::mac::{Macro, MacroDelimiter};
@@ -436,16 +453,19 @@ pub mod parse_quote;
     feature = "proc-macro"
 ))]
 #[doc(hidden)]
 pub mod parse_macro_input;
 
 #[cfg(all(feature = "parsing", feature = "printing"))]
 pub mod spanned;
 
+#[cfg(all(feature = "parsing", feature = "full"))]
+mod whitespace;
+
 mod gen {
     /// Syntax tree traversal to walk a shared borrow of a syntax tree.
     ///
     /// Each method of the [`Visit`] trait is a hook that can be overridden to
     /// customize the behavior when visiting the corresponding type of node. By
     /// default, every method recursively visits the substructure of the input
     /// by invoking the right visitor method of each of its fields.
     ///
@@ -477,17 +497,17 @@ mod gen {
     ///     v.visit_expr(&*node.left);
     ///     v.visit_bin_op(&node.op);
     ///     v.visit_expr(&*node.right);
     /// }
     ///
     /// /* ... */
     /// ```
     ///
-    /// *This module is available if Syn is built with the `"visit"` feature.*
+    /// *This module is available only if Syn is built with the `"visit"` feature.*
     ///
     /// <br>
     ///
     /// # Example
     ///
     /// This visitor will print the name of every freestanding function in the
     /// syntax tree, including nested functions.
     ///
@@ -598,17 +618,17 @@ mod gen {
     ///     v.visit_expr_mut(&mut *node.left);
     ///     v.visit_bin_op_mut(&mut node.op);
     ///     v.visit_expr_mut(&mut *node.right);
     /// }
     ///
     /// /* ... */
     /// ```
     ///
-    /// *This module is available if Syn is built with the `"visit-mut"`
+    /// *This module is available only if Syn is built with the `"visit-mut"`
     /// feature.*
     ///
     /// <br>
     ///
     /// # Example
     ///
     /// This mut visitor replace occurrences of u256 suffixed integer literals
     /// like `999u256` with a macro invocation `bigint::u256!(999)`.
@@ -697,17 +717,17 @@ mod gen {
     ///         op: v.fold_bin_op(node.op),
     ///         right: Box::new(v.fold_expr(*node.right)),
     ///     }
     /// }
     ///
     /// /* ... */
     /// ```
     ///
-    /// *This module is available if Syn is built with the `"fold"` feature.*
+    /// *This module is available only if Syn is built with the `"fold"` feature.*
     ///
     /// <br>
     ///
     /// # Example
     ///
     /// This fold inserts parentheses to fully parenthesizes any expression.
     ///
     /// ```
@@ -739,43 +759,63 @@ mod gen {
     ///
     ///     // Output: (((a)()) + (((b)((1))) * ((c).d)))
     /// }
     /// ```
     #[cfg(feature = "fold")]
     #[rustfmt::skip]
     pub mod fold;
 
+    #[cfg(feature = "clone-impls")]
+    #[rustfmt::skip]
+    mod clone;
+
+    #[cfg(feature = "extra-traits")]
+    #[rustfmt::skip]
+    mod eq;
+
+    #[cfg(feature = "extra-traits")]
+    #[rustfmt::skip]
+    mod hash;
+
+    #[cfg(feature = "extra-traits")]
+    #[rustfmt::skip]
+    mod debug;
+
     #[cfg(any(feature = "full", feature = "derive"))]
     #[path = "../gen_helper.rs"]
     mod helper;
 }
 pub use crate::gen::*;
 
 // Not public API.
 #[doc(hidden)]
 pub mod export;
 
 mod custom_keyword;
 mod custom_punctuation;
 mod sealed;
+mod span;
+mod thread;
 
 #[cfg(feature = "parsing")]
 mod lookahead;
 
 #[cfg(feature = "parsing")]
 pub mod parse;
 
-mod span;
+#[cfg(feature = "full")]
+mod reserved;
+
+#[cfg(all(any(feature = "full", feature = "derive"), feature = "parsing"))]
+mod verbatim;
 
 #[cfg(all(any(feature = "full", feature = "derive"), feature = "printing"))]
 mod print;
 
-mod thread;
-
 ////////////////////////////////////////////////////////////////////////////////
 
 #[allow(dead_code, non_camel_case_types)]
 struct private;
 
 // https://github.com/rust-lang/rust/issues/62830
 #[cfg(feature = "parsing")]
 mod rustdoc_workaround {
@@ -795,24 +835,24 @@ pub use crate::error::{Error, Result};
 /// messages.
 ///
 /// This function parses a `proc_macro::TokenStream` which is the type used for
 /// interop with the compiler in a procedural macro. To parse a
 /// `proc_macro2::TokenStream`, use [`syn::parse2`] instead.
 ///
 /// [`syn::parse2`]: parse2
 ///
-/// *This function is available if Syn is built with both the `"parsing"` and
+/// *This function is available only if Syn is built with both the `"parsing"` and
 /// `"proc-macro"` features.*
 ///
 /// # Examples
 ///
 /// ```
-/// extern crate proc_macro;
-///
+/// # extern crate proc_macro;
+/// #
 /// use proc_macro::TokenStream;
 /// use quote::quote;
 /// use syn::DeriveInput;
 ///
 /// # const IGNORE_TOKENS: &str = stringify! {
 /// #[proc_macro_derive(MyMacro)]
 /// # };
 /// pub fn my_macro(input: TokenStream) -> TokenStream {
@@ -842,25 +882,25 @@ pub fn parse<T: parse::Parse>(tokens: pr
 /// This function parses a `proc_macro2::TokenStream` which is commonly useful
 /// when the input comes from a node of the Syn syntax tree, for example the
 /// body tokens of a [`Macro`] node. When in a procedural macro parsing the
 /// `proc_macro::TokenStream` provided by the compiler, use [`syn::parse`]
 /// instead.
 ///
 /// [`syn::parse`]: parse()
 ///
-/// *This function is available if Syn is built with the `"parsing"` feature.*
+/// *This function is available only if Syn is built with the `"parsing"` feature.*
 #[cfg(feature = "parsing")]
 pub fn parse2<T: parse::Parse>(tokens: proc_macro2::TokenStream) -> Result<T> {
     parse::Parser::parse2(T::parse, tokens)
 }
 
 /// Parse a string of Rust code into the chosen syntax tree node.
 ///
-/// *This function is available if Syn is built with the `"parsing"` feature.*
+/// *This function is available only if Syn is built with the `"parsing"` feature.*
 ///
 /// # Hygiene
 ///
 /// Every span in the resulting syntax tree will be set to resolve at the macro
 /// call site.
 ///
 /// # Examples
 ///
@@ -869,19 +909,17 @@ pub fn parse2<T: parse::Parse>(tokens: p
 ///
 /// fn run() -> Result<()> {
 ///     let code = "assert_eq!(u8::max_value(), 255)";
 ///     let expr = syn::parse_str::<Expr>(code)?;
 ///     println!("{:#?}", expr);
 ///     Ok(())
 /// }
 /// #
-/// # fn main() {
-/// #     run().unwrap();
-/// # }
+/// # run().unwrap();
 /// ```
 #[cfg(feature = "parsing")]
 pub fn parse_str<T: parse::Parse>(s: &str) -> Result<T> {
     parse::Parser::parse_str(T::parse, s)
 }
 
 // FIXME the name parse_file makes it sound like you might pass in a path to a
 // file, rather than the content.
@@ -889,17 +927,17 @@ pub fn parse_str<T: parse::Parse>(s: &st
 ///
 /// This is different from `syn::parse_str::<File>(content)` in two ways:
 ///
 /// - It discards a leading byte order mark `\u{FEFF}` if the file has one.
 /// - It preserves the shebang line of the file, such as `#!/usr/bin/env rustx`.
 ///
 /// If present, either of these would be an error using `from_str`.
 ///
-/// *This function is available if Syn is built with the `"parsing"` and
+/// *This function is available only if Syn is built with the `"parsing"` and
 /// `"full"` features.*
 ///
 /// # Examples
 ///
 /// ```no_run
 /// use std::error::Error;
 /// use std::fs::File;
 /// use std::io::Read;
@@ -913,35 +951,36 @@ pub fn parse_str<T: parse::Parse>(s: &st
 ///     if let Some(shebang) = ast.shebang {
 ///         println!("{}", shebang);
 ///     }
 ///     println!("{} items", ast.items.len());
 ///
 ///     Ok(())
 /// }
 /// #
-/// # fn main() {
-/// #     run().unwrap();
-/// # }
+/// # run().unwrap();
 /// ```
 #[cfg(all(feature = "parsing", feature = "full"))]
 pub fn parse_file(mut content: &str) -> Result<File> {
     // Strip the BOM if it is present
     const BOM: &str = "\u{feff}";
     if content.starts_with(BOM) {
         content = &content[BOM.len()..];
     }
 
     let mut shebang = None;
-    if content.starts_with("#!") && !content.starts_with("#![") {
-        if let Some(idx) = content.find('\n') {
-            shebang = Some(content[..idx].to_string());
-            content = &content[idx..];
-        } else {
-            shebang = Some(content.to_string());
-            content = "";
+    if content.starts_with("#!") {
+        let rest = whitespace::skip(&content[2..]);
+        if !rest.starts_with('[') {
+            if let Some(idx) = content.find('\n') {
+                shebang = Some(content[..idx].to_string());
+                content = &content[idx..];
+            } else {
+                shebang = Some(content.to_string());
+                content = "";
+            }
         }
     }
 
     let mut file: File = parse_str(content)?;
     file.shebang = shebang;
     Ok(file)
 }
diff --git a/third_party/rust/syn/src/lifetime.rs b/third_party/rust/syn/src/lifetime.rs
--- a/third_party/rust/syn/src/lifetime.rs
+++ b/third_party/rust/syn/src/lifetime.rs
@@ -13,20 +13,18 @@ use crate::lookahead;
 ///
 /// - Must start with an apostrophe.
 /// - Must not consist of just an apostrophe: `'`.
 /// - Character after the apostrophe must be `_` or a Unicode code point with
 ///   the XID_Start property.
 /// - All following characters must be Unicode code points with the XID_Continue
 ///   property.
 ///
-/// *This type is available if Syn is built with the `"derive"` or `"full"`
+/// *This type is available only if Syn is built with the `"derive"` or `"full"`
 /// feature.*
-#[cfg_attr(feature = "extra-traits", derive(Debug))]
-#[derive(Clone)]
 pub struct Lifetime {
     pub apostrophe: Span,
     pub ident: Ident,
 }
 
 impl Lifetime {
     /// # Panics
     ///
@@ -67,16 +65,25 @@ impl Lifetime {
 
 impl Display for Lifetime {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         "'".fmt(formatter)?;
         self.ident.fmt(formatter)
     }
 }
 
+impl Clone for Lifetime {
+    fn clone(&self) -> Self {
+        Lifetime {
+            apostrophe: self.apostrophe,
+            ident: self.ident.clone(),
+        }
+    }
+}
+
 impl PartialEq for Lifetime {
     fn eq(&self, other: &Lifetime) -> bool {
         self.ident.eq(&other.ident)
     }
 }
 
 impl Eq for Lifetime {}
 
diff --git a/third_party/rust/syn/src/lit.rs b/third_party/rust/syn/src/lit.rs
--- a/third_party/rust/syn/src/lit.rs
+++ b/third_party/rust/syn/src/lit.rs
@@ -17,28 +17,25 @@ use std::hash::{Hash, Hasher};
 use crate::lookahead;
 #[cfg(feature = "parsing")]
 use crate::parse::{Parse, Parser};
 use crate::{Error, Result};
 
 ast_enum_of_structs! {
     /// A Rust literal such as a string or integer or boolean.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
-    /// feature.*
-    ///
     /// # Syntax tree enum
     ///
     /// This type is a [syntax tree enum].
     ///
     /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums
     //
     // TODO: change syntax-tree-enum link to an intra rustdoc link, currently
     // blocked on https://github.com/rust-lang/rust/issues/62833
-    pub enum Lit #manual_extra_traits {
+    pub enum Lit {
         /// A UTF-8 string literal: `"foo"`.
         Str(LitStr),
 
         /// A byte string literal: `b"foo"`.
         ByteStr(LitByteStr),
 
         /// A byte literal: `b'f'`.
         Byte(LitByte),
@@ -59,184 +56,98 @@ ast_enum_of_structs! {
 
         /// A raw token literal not interpreted by Syn.
         Verbatim(Literal),
     }
 }
 
 ast_struct! {
     /// A UTF-8 string literal: `"foo"`.
-    ///
-    /// *This type is available if Syn is built with the `"derive"` or
-    /// `"full"` feature.*
-    pub struct LitStr #manual_extra_traits_debug {
-        repr: Box<LitStrRepr>,
+    pub struct LitStr {
+        repr: Box<LitRepr>,
     }
 }
 
-#[cfg_attr(feature = "clone-impls", derive(Clone))]
-struct LitStrRepr {
-    token: Literal,
-    suffix: Box<str>,
-}
-
 ast_struct! {
     /// A byte string literal: `b"foo"`.
-    ///
-    /// *This type is available if Syn is built with the `"derive"` or
-    /// `"full"` feature.*
-    pub struct LitByteStr #manual_extra_traits_debug {
-        token: Literal,
+    pub struct LitByteStr {
+        repr: Box<LitRepr>,
     }
 }
 
 ast_struct! {
     /// A byte literal: `b'f'`.
-    ///
-    /// *This type is available if Syn is built with the `"derive"` or
-    /// `"full"` feature.*
-    pub struct LitByte #manual_extra_traits_debug {
-        token: Literal,
+    pub struct LitByte {
+        repr: Box<LitRepr>,
     }
 }
 
 ast_struct! {
     /// A character literal: `'a'`.
-    ///
-    /// *This type is available if Syn is built with the `"derive"` or
-    /// `"full"` feature.*
-    pub struct LitChar #manual_extra_traits_debug {
-        token: Literal,
+    pub struct LitChar {
+        repr: Box<LitRepr>,
     }
 }
 
+struct LitRepr {
+    token: Literal,
+    suffix: Box<str>,
+}
+
 ast_struct! {
     /// An integer literal: `1` or `1u16`.
-    ///
-    /// *This type is available if Syn is built with the `"derive"` or
-    /// `"full"` feature.*
-    pub struct LitInt #manual_extra_traits_debug {
+    pub struct LitInt {
         repr: Box<LitIntRepr>,
     }
 }
 
-#[cfg_attr(feature = "clone-impls", derive(Clone))]
 struct LitIntRepr {
     token: Literal,
     digits: Box<str>,
     suffix: Box<str>,
 }
 
 ast_struct! {
     /// A floating point literal: `1f64` or `1.0e10f64`.
     ///
     /// Must be finite. May not be infinte or NaN.
-    ///
-    /// *This type is available if Syn is built with the `"derive"` or
-    /// `"full"` feature.*
-    pub struct LitFloat #manual_extra_traits_debug {
+    pub struct LitFloat {
         repr: Box<LitFloatRepr>,
     }
 }
 
-#[cfg_attr(feature = "clone-impls", derive(Clone))]
 struct LitFloatRepr {
     token: Literal,
     digits: Box<str>,
     suffix: Box<str>,
 }
 
 ast_struct! {
     /// A boolean literal: `true` or `false`.
-    ///
-    /// *This type is available if Syn is built with the `"derive"` or
-    /// `"full"` feature.*
-    pub struct LitBool #manual_extra_traits_debug {
+    pub struct LitBool {
         pub value: bool,
         pub span: Span,
     }
 }
 
-#[cfg(feature = "extra-traits")]
-impl Eq for Lit {}
-
-#[cfg(feature = "extra-traits")]
-impl PartialEq for Lit {
-    fn eq(&self, other: &Self) -> bool {
-        match (self, other) {
-            (Lit::Str(this), Lit::Str(other)) => this == other,
-            (Lit::ByteStr(this), Lit::ByteStr(other)) => this == other,
-            (Lit::Byte(this), Lit::Byte(other)) => this == other,
-            (Lit::Char(this), Lit::Char(other)) => this == other,
-            (Lit::Int(this), Lit::Int(other)) => this == other,
-            (Lit::Float(this), Lit::Float(other)) => this == other,
-            (Lit::Bool(this), Lit::Bool(other)) => this == other,
-            (Lit::Verbatim(this), Lit::Verbatim(other)) => this.to_string() == other.to_string(),
-            _ => false,
-        }
-    }
-}
-
-#[cfg(feature = "extra-traits")]
-impl Hash for Lit {
-    fn hash<H>(&self, hash: &mut H)
-    where
-        H: Hasher,
-    {
-        match self {
-            Lit::Str(lit) => {
-                hash.write_u8(0);
-                lit.hash(hash);
-            }
-            Lit::ByteStr(lit) => {
-                hash.write_u8(1);
-                lit.hash(hash);
-            }
-            Lit::Byte(lit) => {
-                hash.write_u8(2);
-                lit.hash(hash);
-            }
-            Lit::Char(lit) => {
-                hash.write_u8(3);
-                lit.hash(hash);
-            }
-            Lit::Int(lit) => {
-                hash.write_u8(4);
-                lit.hash(hash);
-            }
-            Lit::Float(lit) => {
-                hash.write_u8(5);
-                lit.hash(hash);
-            }
-            Lit::Bool(lit) => {
-                hash.write_u8(6);
-                lit.hash(hash);
-            }
-            Lit::Verbatim(lit) => {
-                hash.write_u8(7);
-                lit.to_string().hash(hash);
-            }
-        }
-    }
-}
-
 impl LitStr {
     pub fn new(value: &str, span: Span) -> Self {
-        let mut lit = Literal::string(value);
-        lit.set_span(span);
+        let mut token = Literal::string(value);
+        token.set_span(span);
         LitStr {
-            repr: Box::new(LitStrRepr {
-                token: lit,
+            repr: Box::new(LitRepr {
+                token,
                 suffix: Box::<str>::default(),
             }),
         }
     }
 
     pub fn value(&self) -> String {
-        let (value, _) = value::parse_lit_str(&self.repr.token.to_string());
+        let repr = self.repr.token.to_string();
+        let (value, _suffix) = value::parse_lit_str(&repr);
         String::from(value)
     }
 
     /// Parse a syntax tree node from the content of this string literal.
     ///
     /// All spans in the syntax tree will point to the span of this `LitStr`.
     ///
     /// # Example
@@ -306,17 +217,17 @@ impl LitStr {
                 .map(|token| respan_token_tree(token, span))
                 .collect()
         }
 
         // Token tree with every span replaced by the given one.
         fn respan_token_tree(mut token: TokenTree, span: Span) -> TokenTree {
             match &mut token {
                 TokenTree::Group(g) => {
-                    let stream = respan_token_stream(g.stream().clone(), span);
+                    let stream = respan_token_stream(g.stream(), span);
                     *g = Group::new(g.delimiter(), stream);
                     g.set_span(span);
                 }
                 other => other.set_span(span),
             }
             token
         }
 
@@ -340,86 +251,124 @@ impl LitStr {
         &self.repr.suffix
     }
 }
 
 impl LitByteStr {
     pub fn new(value: &[u8], span: Span) -> Self {
         let mut token = Literal::byte_string(value);
         token.set_span(span);
-        LitByteStr { token }
+        LitByteStr {
+            repr: Box::new(LitRepr {
+                token,
+                suffix: Box::<str>::default(),
+            }),
+        }
     }
 
     pub fn value(&self) -> Vec<u8> {
-        value::parse_lit_byte_str(&self.token.to_string())
+        let repr = self.repr.token.to_string();
+        let (value, _suffix) = value::parse_lit_byte_str(&repr);
+        value
     }
 
     pub fn span(&self) -> Span {
-        self.token.span()
+        self.repr.token.span()
     }
 
     pub fn set_span(&mut self, span: Span) {
-        self.token.set_span(span)
+        self.repr.token.set_span(span)
+    }
+
+    pub fn suffix(&self) -> &str {
+        &self.repr.suffix
     }
 }
 
 impl LitByte {
     pub fn new(value: u8, span: Span) -> Self {
         let mut token = Literal::u8_suffixed(value);
         token.set_span(span);
-        LitByte { token }
+        LitByte {
+            repr: Box::new(LitRepr {
+                token,
+                suffix: Box::<str>::default(),
+            }),
+        }
     }
 
     pub fn value(&self) -> u8 {
-        value::parse_lit_byte(&self.token.to_string())
+        let repr = self.repr.token.to_string();
+        let (value, _suffix) = value::parse_lit_byte(&repr);
+        value
     }
 
     pub fn span(&self) -> Span {
-        self.token.span()
+        self.repr.token.span()
     }
 
     pub fn set_span(&mut self, span: Span) {
-        self.token.set_span(span)
+        self.repr.token.set_span(span)
+    }
+
+    pub fn suffix(&self) -> &str {
+        &self.repr.suffix
     }
 }
 
 impl LitChar {
     pub fn new(value: char, span: Span) -> Self {
         let mut token = Literal::character(value);
         token.set_span(span);
-        LitChar { token }
+        LitChar {
+            repr: Box::new(LitRepr {
+                token,
+                suffix: Box::<str>::default(),
+            }),
+        }
     }
 
     pub fn value(&self) -> char {
-        value::parse_lit_char(&self.token.to_string())
+        let repr = self.repr.token.to_string();
+        let (value, _suffix) = value::parse_lit_char(&repr);
+        value
     }
 
     pub fn span(&self) -> Span {
-        self.token.span()
+        self.repr.token.span()
     }
 
     pub fn set_span(&mut self, span: Span) {
-        self.token.set_span(span)
+        self.repr.token.set_span(span)
+    }
+
+    pub fn suffix(&self) -> &str {
+        &self.repr.suffix
     }
 }
 
 impl LitInt {
     pub fn new(repr: &str, span: Span) -> Self {
-        if let Some((digits, suffix)) = value::parse_lit_int(repr) {
-            let mut token = value::to_literal(repr);
-            token.set_span(span);
-            LitInt {
-                repr: Box::new(LitIntRepr {
-                    token,
-                    digits,
-                    suffix,
-                }),
-            }
-        } else {
-            panic!("Not an integer literal: `{}`", repr);
+        let (digits, suffix) = match value::parse_lit_int(repr) {
+            Some(parse) => parse,
+            None => panic!("Not an integer literal: `{}`", repr),
+        };
+
+        let mut token = match value::to_literal(repr, &digits, &suffix) {
+            Some(token) => token,
+            None => panic!("Unsupported integer literal: `{}`", repr),
+        };
+
+        token.set_span(span);
+        LitInt {
+            repr: Box::new(LitIntRepr {
+                token,
+                digits,
+                suffix,
+            }),
         }
     }
 
     pub fn base10_digits(&self) -> &str {
         &self.repr.digits
     }
 
     /// Parses the literal into a selected number type.
@@ -487,28 +436,33 @@ impl From<Literal> for LitInt {
 impl Display for LitInt {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         self.repr.token.fmt(formatter)
     }
 }
 
 impl LitFloat {
     pub fn new(repr: &str, span: Span) -> Self {
-        if let Some((digits, suffix)) = value::parse_lit_float(repr) {
-            let mut token = value::to_literal(repr);
-            token.set_span(span);
-            LitFloat {
-                repr: Box::new(LitFloatRepr {
-                    token,
-                    digits,
-                    suffix,
-                }),
-            }
-        } else {
-            panic!("Not a float literal: `{}`", repr);
+        let (digits, suffix) = match value::parse_lit_float(repr) {
+            Some(parse) => parse,
+            None => panic!("Not a float literal: `{}`", repr),
+        };
+
+        let mut token = match value::to_literal(repr, &digits, &suffix) {
+            Some(token) => token,
+            None => panic!("Unsupported float literal: `{}`", repr),
+        };
+
+        token.set_span(span);
+        LitFloat {
+            repr: Box::new(LitFloatRepr {
+                token,
+                digits,
+                suffix,
+            }),
         }
     }
 
     pub fn base10_digits(&self) -> &str {
         &self.repr.digits
     }
 
     pub fn base10_parse<N>(&self) -> Result<N>
@@ -570,35 +524,35 @@ mod debug_impls {
                 .finish()
         }
     }
 
     impl Debug for LitByteStr {
         fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
             formatter
                 .debug_struct("LitByteStr")
-                .field("token", &format_args!("{}", self.token))
+                .field("token", &format_args!("{}", self.repr.token))
                 .finish()
         }
     }
 
     impl Debug for LitByte {
         fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
             formatter
                 .debug_struct("LitByte")
-                .field("token", &format_args!("{}", self.token))
+                .field("token", &format_args!("{}", self.repr.token))
                 .finish()
         }
     }
 
     impl Debug for LitChar {
         fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
             formatter
                 .debug_struct("LitChar")
-                .field("token", &format_args!("{}", self.token))
+                .field("token", &format_args!("{}", self.repr.token))
                 .finish()
         }
     }
 
     impl Debug for LitInt {
         fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
             formatter
                 .debug_struct("LitInt")
@@ -621,61 +575,102 @@ mod debug_impls {
             formatter
                 .debug_struct("LitBool")
                 .field("value", &self.value)
                 .finish()
         }
     }
 }
 
+#[cfg(feature = "clone-impls")]
+impl Clone for LitRepr {
+    fn clone(&self) -> Self {
+        LitRepr {
+            token: self.token.clone(),
+            suffix: self.suffix.clone(),
+        }
+    }
+}
+
+#[cfg(feature = "clone-impls")]
+impl Clone for LitIntRepr {
+    fn clone(&self) -> Self {
+        LitIntRepr {
+            token: self.token.clone(),
+            digits: self.digits.clone(),
+            suffix: self.suffix.clone(),
+        }
+    }
+}
+
+#[cfg(feature = "clone-impls")]
+impl Clone for LitFloatRepr {
+    fn clone(&self) -> Self {
+        LitFloatRepr {
+            token: self.token.clone(),
+            digits: self.digits.clone(),
+            suffix: self.suffix.clone(),
+        }
+    }
+}
+
 macro_rules! lit_extra_traits {
-    ($ty:ident, $($field:ident).+) => {
-        #[cfg(feature = "extra-traits")]
-        impl Eq for $ty {}
+    ($ty:ident) => {
+        #[cfg(feature = "clone-impls")]
+        impl Clone for $ty {
+            fn clone(&self) -> Self {
+                $ty {
+                    repr: self.repr.clone(),
+                }
+            }
+        }
 
         #[cfg(feature = "extra-traits")]
         impl PartialEq for $ty {
             fn eq(&self, other: &Self) -> bool {
-                self.$($field).+.to_string() == other.$($field).+.to_string()
+                self.repr.token.to_string() == other.repr.token.to_string()
             }
         }
 
         #[cfg(feature = "extra-traits")]
         impl Hash for $ty {
             fn hash<H>(&self, state: &mut H)
             where
                 H: Hasher,
             {
-                self.$($field).+.to_string().hash(state);
+                self.repr.token.to_string().hash(state);
             }
         }
 
         #[cfg(feature = "parsing")]
         #[doc(hidden)]
         #[allow(non_snake_case)]
         pub fn $ty(marker: lookahead::TokenMarker) -> $ty {
             match marker {}
         }
     };
 }
 
-lit_extra_traits!(LitStr, repr.token);
-lit_extra_traits!(LitByteStr, token);
-lit_extra_traits!(LitByte, token);
-lit_extra_traits!(LitChar, token);
-lit_extra_traits!(LitInt, repr.token);
-lit_extra_traits!(LitFloat, repr.token);
-lit_extra_traits!(LitBool, value);
+lit_extra_traits!(LitStr);
+lit_extra_traits!(LitByteStr);
+lit_extra_traits!(LitByte);
+lit_extra_traits!(LitChar);
+lit_extra_traits!(LitInt);
+lit_extra_traits!(LitFloat);
+
+#[cfg(feature = "parsing")]
+#[doc(hidden)]
+#[allow(non_snake_case)]
+pub fn LitBool(marker: lookahead::TokenMarker) -> LitBool {
+    match marker {}
+}
 
 ast_enum! {
     /// The style of a string literal, either plain quoted or a raw string like
     /// `r##"data"##`.
-    ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
-    /// feature.*
     pub enum StrStyle #no_visit {
         /// An ordinary string like `"data"`.
         Cooked,
         /// A raw string like `r##"data"##`.
         ///
         /// The unsigned integer is the number of `#` symbols used.
         Raw(usize),
     }
@@ -686,43 +681,93 @@ ast_enum! {
 #[allow(non_snake_case)]
 pub fn Lit(marker: lookahead::TokenMarker) -> Lit {
     match marker {}
 }
 
 #[cfg(feature = "parsing")]
 pub mod parsing {
     use super::*;
+    use crate::buffer::Cursor;
     use crate::parse::{Parse, ParseStream, Result};
+    use proc_macro2::Punct;
 
     impl Parse for Lit {
         fn parse(input: ParseStream) -> Result<Self> {
             input.step(|cursor| {
                 if let Some((lit, rest)) = cursor.literal() {
                     return Ok((Lit::new(lit), rest));
                 }
-                while let Some((ident, rest)) = cursor.ident() {
-                    let value = if ident == "true" {
-                        true
-                    } else if ident == "false" {
-                        false
-                    } else {
-                        break;
-                    };
-                    let lit_bool = LitBool {
-                        value,
-                        span: ident.span(),
-                    };
-                    return Ok((Lit::Bool(lit_bool), rest));
+
+                if let Some((ident, rest)) = cursor.ident() {
+                    let value = ident == "true";
+                    if value || ident == "false" {
+                        let lit_bool = LitBool {
+                            value,
+                            span: ident.span(),
+                        };
+                        return Ok((Lit::Bool(lit_bool), rest));
+                    }
                 }
+
+                if let Some((punct, rest)) = cursor.punct() {
+                    if punct.as_char() == '-' {
+                        if let Some((lit, rest)) = parse_negative_lit(punct, rest) {
+                            return Ok((lit, rest));
+                        }
+                    }
+                }
+
                 Err(cursor.error("expected literal"))
             })
         }
     }
 
+    fn parse_negative_lit(neg: Punct, cursor: Cursor) -> Option<(Lit, Cursor)> {
+        let (lit, rest) = cursor.literal()?;
+
+        let mut span = neg.span();
+        span = span.join(lit.span()).unwrap_or(span);
+
+        let mut repr = lit.to_string();
+        repr.insert(0, '-');
+
+        if !(repr.ends_with("f32") || repr.ends_with("f64")) {
+            if let Some((digits, suffix)) = value::parse_lit_int(&repr) {
+                if let Some(mut token) = value::to_literal(&repr, &digits, &suffix) {
+                    token.set_span(span);
+                    return Some((
+                        Lit::Int(LitInt {
+                            repr: Box::new(LitIntRepr {
+                                token,
+                                digits,
+                                suffix,
+                            }),
+                        }),
+                        rest,
+                    ));
+                }
+            }
+        }
+
+        let (digits, suffix) = value::parse_lit_float(&repr)?;
+        let mut token = value::to_literal(&repr, &digits, &suffix)?;
+        token.set_span(span);
+        Some((
+            Lit::Float(LitFloat {
+                repr: Box::new(LitFloatRepr {
+                    token,
+                    digits,
+                    suffix,
+                }),
+            }),
+            rest,
+        ))
+    }
+
     impl Parse for LitStr {
         fn parse(input: ParseStream) -> Result<Self> {
             let head = input.fork();
             match input.parse()? {
                 Lit::Str(lit) => Ok(lit),
                 _ => Err(head.error("expected string literal")),
             }
         }
@@ -798,29 +843,29 @@ mod printing {
     impl ToTokens for LitStr {
         fn to_tokens(&self, tokens: &mut TokenStream) {
             self.repr.token.to_tokens(tokens);
         }
     }
 
     impl ToTokens for LitByteStr {
         fn to_tokens(&self, tokens: &mut TokenStream) {
-            self.token.to_tokens(tokens);
+            self.repr.token.to_tokens(tokens);
         }
     }
 
     impl ToTokens for LitByte {
         fn to_tokens(&self, tokens: &mut TokenStream) {
-            self.token.to_tokens(tokens);
+            self.repr.token.to_tokens(tokens);
         }
     }
 
     impl ToTokens for LitChar {
         fn to_tokens(&self, tokens: &mut TokenStream) {
-            self.token.to_tokens(tokens);
+            self.repr.token.to_tokens(tokens);
         }
     }
 
     impl ToTokens for LitInt {
         fn to_tokens(&self, tokens: &mut TokenStream) {
             self.repr.token.to_tokens(tokens);
         }
     }
@@ -850,30 +895,39 @@ mod value {
         /// Interpret a Syn literal from a proc-macro2 literal.
         pub fn new(token: Literal) -> Self {
             let repr = token.to_string();
 
             match byte(&repr, 0) {
                 b'"' | b'r' => {
                     let (_, suffix) = parse_lit_str(&repr);
                     return Lit::Str(LitStr {
-                        repr: Box::new(LitStrRepr { token, suffix }),
+                        repr: Box::new(LitRepr { token, suffix }),
                     });
                 }
                 b'b' => match byte(&repr, 1) {
                     b'"' | b'r' => {
-                        return Lit::ByteStr(LitByteStr { token });
+                        let (_, suffix) = parse_lit_byte_str(&repr);
+                        return Lit::ByteStr(LitByteStr {
+                            repr: Box::new(LitRepr { token, suffix }),
+                        });
                     }
                     b'\'' => {
-                        return Lit::Byte(LitByte { token });
+                        let (_, suffix) = parse_lit_byte(&repr);
+                        return Lit::Byte(LitByte {
+                            repr: Box::new(LitRepr { token, suffix }),
+                        });
                     }
                     _ => {}
                 },
                 b'\'' => {
-                    return Lit::Char(LitChar { token });
+                    let (_, suffix) = parse_lit_char(&repr);
+                    return Lit::Char(LitChar {
+                        repr: Box::new(LitRepr { token, suffix }),
+                    });
                 }
                 b'0'..=b'9' | b'-' => {
                     if !(repr.ends_with("f32") || repr.ends_with("f64")) {
                         if let Some((digits, suffix)) = parse_lit_int(&repr) {
                             return Lit::Int(LitInt {
                                 repr: Box::new(LitIntRepr {
                                     token,
                                     digits,
@@ -900,16 +954,54 @@ mod value {
                         });
                     }
                 }
                 _ => {}
             }
 
             panic!("Unrecognized literal: `{}`", repr);
         }
+
+        pub fn suffix(&self) -> &str {
+            match self {
+                Lit::Str(lit) => lit.suffix(),
+                Lit::ByteStr(lit) => lit.suffix(),
+                Lit::Byte(lit) => lit.suffix(),
+                Lit::Char(lit) => lit.suffix(),
+                Lit::Int(lit) => lit.suffix(),
+                Lit::Float(lit) => lit.suffix(),
+                Lit::Bool(_) | Lit::Verbatim(_) => "",
+            }
+        }
+
+        pub fn span(&self) -> Span {
+            match self {
+                Lit::Str(lit) => lit.span(),
+                Lit::ByteStr(lit) => lit.span(),
+                Lit::Byte(lit) => lit.span(),
+                Lit::Char(lit) => lit.span(),
+                Lit::Int(lit) => lit.span(),
+                Lit::Float(lit) => lit.span(),
+                Lit::Bool(lit) => lit.span,
+                Lit::Verbatim(lit) => lit.span(),
+            }
+        }
+
+        pub fn set_span(&mut self, span: Span) {
+            match self {
+                Lit::Str(lit) => lit.set_span(span),
+                Lit::ByteStr(lit) => lit.set_span(span),
+                Lit::Byte(lit) => lit.set_span(span),
+                Lit::Char(lit) => lit.set_span(span),
+                Lit::Int(lit) => lit.set_span(span),
+                Lit::Float(lit) => lit.set_span(span),
+                Lit::Bool(lit) => lit.span = span,
+                Lit::Verbatim(lit) => lit.set_span(span),
+            }
+        }
     }
 
     /// Get the byte at offset idx, or a default of `b'\0'` if we're looking
     /// past the end of the input buffer.
     pub fn byte<S: AsRef<[u8]> + ?Sized>(s: &S, idx: usize) -> u8 {
         let s = s.as_ref();
         if idx < s.len() {
             s[idx]
@@ -999,140 +1091,144 @@ mod value {
         assert_eq!(byte(s, 0), b'r');
         s = &s[1..];
 
         let mut pounds = 0;
         while byte(s, pounds) == b'#' {
             pounds += 1;
         }
         assert_eq!(byte(s, pounds), b'"');
-        assert_eq!(byte(s, s.len() - pounds - 1), b'"');
-        for end in s[s.len() - pounds..].bytes() {
+        let close = s.rfind('"').unwrap();
+        for end in s[close + 1..close + 1 + pounds].bytes() {
             assert_eq!(end, b'#');
         }
 
-        let content = s[pounds + 1..s.len() - pounds - 1]
-            .to_owned()
-            .into_boxed_str();
-        let suffix = Box::<str>::default(); // todo
+        let content = s[pounds + 1..close].to_owned().into_boxed_str();
+        let suffix = s[close + 1 + pounds..].to_owned().into_boxed_str();
         (content, suffix)
     }
 
-    pub fn parse_lit_byte_str(s: &str) -> Vec<u8> {
+    // Returns (content, suffix).
+    pub fn parse_lit_byte_str(s: &str) -> (Vec<u8>, Box<str>) {
         assert_eq!(byte(s, 0), b'b');
         match byte(s, 1) {
             b'"' => parse_lit_byte_str_cooked(s),
             b'r' => parse_lit_byte_str_raw(s),
             _ => unreachable!(),
         }
     }
 
     // Clippy false positive
     // https://github.com/rust-lang-nursery/rust-clippy/issues/2329
     #[allow(clippy::needless_continue)]
-    fn parse_lit_byte_str_cooked(mut s: &str) -> Vec<u8> {
+    fn parse_lit_byte_str_cooked(mut s: &str) -> (Vec<u8>, Box<str>) {
         assert_eq!(byte(s, 0), b'b');
         assert_eq!(byte(s, 1), b'"');
         s = &s[2..];
 
         // We're going to want to have slices which don't respect codepoint boundaries.
-        let mut s = s.as_bytes();
+        let mut v = s.as_bytes();
 
         let mut out = Vec::new();
         'outer: loop {
-            let byte = match byte(s, 0) {
+            let byte = match byte(v, 0) {
                 b'"' => break,
                 b'\\' => {
-                    let b = byte(s, 1);
-                    s = &s[2..];
+                    let b = byte(v, 1);
+                    v = &v[2..];
                     match b {
                         b'x' => {
-                            let (b, rest) = backslash_x(s);
-                            s = rest;
+                            let (b, rest) = backslash_x(v);
+                            v = rest;
                             b
                         }
                         b'n' => b'\n',
                         b'r' => b'\r',
                         b't' => b'\t',
                         b'\\' => b'\\',
                         b'0' => b'\0',
                         b'\'' => b'\'',
                         b'"' => b'"',
                         b'\r' | b'\n' => loop {
-                            let byte = byte(s, 0);
+                            let byte = byte(v, 0);
                             let ch = char::from_u32(u32::from(byte)).unwrap();
                             if ch.is_whitespace() {
-                                s = &s[1..];
+                                v = &v[1..];
                             } else {
                                 continue 'outer;
                             }
                         },
                         b => panic!("unexpected byte {:?} after \\ character in byte literal", b),
                     }
                 }
                 b'\r' => {
-                    assert_eq!(byte(s, 1), b'\n', "Bare CR not allowed in string");
-                    s = &s[2..];
+                    assert_eq!(byte(v, 1), b'\n', "Bare CR not allowed in string");
+                    v = &v[2..];
                     b'\n'
                 }
                 b => {
-                    s = &s[1..];
+                    v = &v[1..];
                     b
                 }
             };
             out.push(byte);
         }
 
-        assert_eq!(s, b"\"");
-        out
+        assert_eq!(byte(v, 0), b'"');
+        let suffix = s[s.len() - v.len() + 1..].to_owned().into_boxed_str();
+        (out, suffix)
     }
 
-    fn parse_lit_byte_str_raw(s: &str) -> Vec<u8> {
+    fn parse_lit_byte_str_raw(s: &str) -> (Vec<u8>, Box<str>) {
         assert_eq!(byte(s, 0), b'b');
-        String::from(parse_lit_str_raw(&s[1..]).0).into_bytes()
+        let (value, suffix) = parse_lit_str_raw(&s[1..]);
+        (String::from(value).into_bytes(), suffix)
     }
 
-    pub fn parse_lit_byte(s: &str) -> u8 {
+    // Returns (value, suffix).
+    pub fn parse_lit_byte(s: &str) -> (u8, Box<str>) {
         assert_eq!(byte(s, 0), b'b');
         assert_eq!(byte(s, 1), b'\'');
 
         // We're going to want to have slices which don't respect codepoint boundaries.
-        let mut s = s[2..].as_bytes();
+        let mut v = s[2..].as_bytes();
 
-        let b = match byte(s, 0) {
+        let b = match byte(v, 0) {
             b'\\' => {
-                let b = byte(s, 1);
-                s = &s[2..];
+                let b = byte(v, 1);
+                v = &v[2..];
                 match b {
                     b'x' => {
-                        let (b, rest) = backslash_x(s);
-                        s = rest;
+                        let (b, rest) = backslash_x(v);
+                        v = rest;
                         b
                     }
                     b'n' => b'\n',
                     b'r' => b'\r',
                     b't' => b'\t',
                     b'\\' => b'\\',
                     b'0' => b'\0',
                     b'\'' => b'\'',
                     b'"' => b'"',
                     b => panic!("unexpected byte {:?} after \\ character in byte literal", b),
                 }
             }
             b => {
-                s = &s[1..];
+                v = &v[1..];
                 b
             }
         };
 
-        assert_eq!(byte(s, 0), b'\'');
-        b
+        assert_eq!(byte(v, 0), b'\'');
+        let suffix = s[s.len() - v.len() + 1..].to_owned().into_boxed_str();
+        (b, suffix)
     }
 
-    pub fn parse_lit_char(mut s: &str) -> char {
+    // Returns (value, suffix).
+    pub fn parse_lit_char(mut s: &str) -> (char, Box<str>) {
         assert_eq!(byte(s, 0), b'\'');
         s = &s[1..];
 
         let ch = match byte(s, 0) {
             b'\\' => {
                 let b = byte(s, 1);
                 s = &s[2..];
                 match b {
@@ -1158,18 +1254,19 @@ mod value {
                 }
             }
             _ => {
                 let ch = next_chr(s);
                 s = &s[ch.len_utf8()..];
                 ch
             }
         };
-        assert_eq!(s, "\'", "Expected end of char literal");
-        ch
+        assert_eq!(byte(s, 0), b'\'');
+        let suffix = s[1..].to_owned().into_boxed_str();
+        (ch, suffix)
     }
 
     fn backslash_x<S>(s: &S) -> (u8, &S)
     where
         S: Index<RangeFrom<usize>, Output = S> + AsRef<[u8]> + ?Sized,
     {
         let mut ch = 0;
         let b0 = byte(s, 0);
@@ -1329,17 +1426,21 @@ mod value {
                     if has_e || has_dot {
                         return None;
                     }
                     has_dot = true;
                     bytes[write] = b'.';
                 }
                 b'e' | b'E' => {
                     if has_e {
-                        return None;
+                        if has_exponent {
+                            break;
+                        } else {
+                            return None;
+                        }
                     }
                     has_e = true;
                     bytes[write] = b'e';
                 }
                 b'-' | b'+' => {
                     if has_sign || has_exponent || !has_e {
                         return None;
                     }
@@ -1367,16 +1468,38 @@ mod value {
         digits.truncate(write);
         if suffix.is_empty() || crate::ident::xid_ok(&suffix) {
             Some((digits.into_boxed_str(), suffix.into_boxed_str()))
         } else {
             None
         }
     }
 
-    pub fn to_literal(s: &str) -> Literal {
-        let stream = s.parse::<TokenStream>().unwrap();
-        match stream.into_iter().next().unwrap() {
-            TokenTree::Literal(l) => l,
-            _ => unreachable!(),
+    pub fn to_literal(repr: &str, digits: &str, suffix: &str) -> Option<Literal> {
+        if repr.starts_with('-') {
+            if suffix == "f64" {
+                digits.parse().ok().map(Literal::f64_suffixed)
+            } else if suffix == "f32" {
+                digits.parse().ok().map(Literal::f32_suffixed)
+            } else if suffix == "i64" {
+                digits.parse().ok().map(Literal::i64_suffixed)
+            } else if suffix == "i32" {
+                digits.parse().ok().map(Literal::i32_suffixed)
+            } else if suffix == "i16" {
+                digits.parse().ok().map(Literal::i16_suffixed)
+            } else if suffix == "i8" {
+                digits.parse().ok().map(Literal::i8_suffixed)
+            } else if !suffix.is_empty() {
+                None
+            } else if digits.contains('.') {
+                digits.parse().ok().map(Literal::f64_unsuffixed)
+            } else {
+                digits.parse().ok().map(Literal::i64_unsuffixed)
+            }
+        } else {
+            let stream = repr.parse::<TokenStream>().unwrap();
+            match stream.into_iter().next().unwrap() {
+                TokenTree::Literal(l) => Some(l),
+                _ => unreachable!(),
+            }
         }
     }
 }
diff --git a/third_party/rust/syn/src/mac.rs b/third_party/rust/syn/src/mac.rs
--- a/third_party/rust/syn/src/mac.rs
+++ b/third_party/rust/syn/src/mac.rs
@@ -1,79 +1,56 @@
 use super::*;
 use crate::token::{Brace, Bracket, Paren};
 use proc_macro2::TokenStream;
 #[cfg(feature = "parsing")]
-use proc_macro2::{Delimiter, Span, TokenTree};
+use proc_macro2::{Delimiter, Group, Span, TokenTree};
 
 #[cfg(feature = "parsing")]
 use crate::parse::{Parse, ParseStream, Parser, Result};
-#[cfg(feature = "extra-traits")]
-use crate::tt::TokenStreamHelper;
-#[cfg(feature = "extra-traits")]
-use std::hash::{Hash, Hasher};
 
 ast_struct! {
     /// A macro invocation: `println!("{}", mac)`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
-    pub struct Macro #manual_extra_traits {
+    pub struct Macro {
         pub path: Path,
         pub bang_token: Token![!],
         pub delimiter: MacroDelimiter,
         pub tokens: TokenStream,
     }
 }
 
 ast_enum! {
     /// A grouping token that surrounds a macro body: `m!(...)` or `m!{...}` or `m![...]`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub enum MacroDelimiter {
         Paren(Paren),
         Brace(Brace),
         Bracket(Bracket),
     }
 }
 
-#[cfg(feature = "extra-traits")]
-impl Eq for Macro {}
-
-#[cfg(feature = "extra-traits")]
-impl PartialEq for Macro {
-    fn eq(&self, other: &Self) -> bool {
-        self.path == other.path
-            && self.bang_token == other.bang_token
-            && self.delimiter == other.delimiter
-            && TokenStreamHelper(&self.tokens) == TokenStreamHelper(&other.tokens)
-    }
-}
-
-#[cfg(feature = "extra-traits")]
-impl Hash for Macro {
-    fn hash<H>(&self, state: &mut H)
-    where
-        H: Hasher,
-    {
-        self.path.hash(state);
-        self.bang_token.hash(state);
-        self.delimiter.hash(state);
-        TokenStreamHelper(&self.tokens).hash(state);
-    }
-}
-
 #[cfg(feature = "parsing")]
-fn delimiter_span(delimiter: &MacroDelimiter) -> Span {
-    match delimiter {
+fn delimiter_span_close(macro_delimiter: &MacroDelimiter) -> Span {
+    let delimiter = match macro_delimiter {
+        MacroDelimiter::Paren(_) => Delimiter::Parenthesis,
+        MacroDelimiter::Brace(_) => Delimiter::Brace,
+        MacroDelimiter::Bracket(_) => Delimiter::Bracket,
+    };
+    let mut group = Group::new(delimiter, TokenStream::new());
+    group.set_span(match macro_delimiter {
         MacroDelimiter::Paren(token) => token.span,
         MacroDelimiter::Brace(token) => token.span,
         MacroDelimiter::Bracket(token) => token.span,
-    }
+    });
+    group.span_close()
 }
 
 impl Macro {
     /// Parse the tokens within the macro invocation's delimiters into a syntax
     /// tree.
     ///
     /// This is equivalent to `syn::parse2::<T>(mac.tokens)` except that it
     /// produces a more useful span when `tokens` is empty.
@@ -158,19 +135,17 @@ impl Macro {
     pub fn parse_body<T: Parse>(&self) -> Result<T> {
         self.parse_body_with(T::parse)
     }
 
     /// Parse the tokens within the macro invocation's delimiters using the
     /// given parser.
     #[cfg(feature = "parsing")]
     pub fn parse_body_with<F: Parser>(&self, parser: F) -> Result<F::Output> {
-        // TODO: see if we can get a group.span_close() span in here as the
-        // scope, rather than the span of the whole group.
-        let scope = delimiter_span(&self.delimiter);
+        let scope = delimiter_span_close(&self.delimiter);
         crate::parse::parse_scoped(parser, scope, self.tokens.clone())
     }
 }
 
 #[cfg(feature = "parsing")]
 pub fn parse_delimiter(input: ParseStream) -> Result<(MacroDelimiter, TokenStream)> {
     input.step(|cursor| {
         if let Some((TokenTree::Group(g), rest)) = cursor.token_tree() {
diff --git a/third_party/rust/syn/src/macros.rs b/third_party/rust/syn/src/macros.rs
--- a/third_party/rust/syn/src/macros.rs
+++ b/third_party/rust/syn/src/macros.rs
@@ -1,56 +1,33 @@
 macro_rules! ast_struct {
     (
         [$($attrs_pub:tt)*]
         struct $name:ident #full $($rest:tt)*
     ) => {
         #[cfg(feature = "full")]
-        #[cfg_attr(feature = "extra-traits", derive(Debug, Eq, PartialEq, Hash))]
-        #[cfg_attr(feature = "clone-impls", derive(Clone))]
         $($attrs_pub)* struct $name $($rest)*
 
         #[cfg(not(feature = "full"))]
-        #[cfg_attr(feature = "extra-traits", derive(Debug, Eq, PartialEq, Hash))]
-        #[cfg_attr(feature = "clone-impls", derive(Clone))]
         $($attrs_pub)* struct $name {
-            _noconstruct: (),
+            _noconstruct: ::std::marker::PhantomData<::proc_macro2::Span>,
         }
 
         #[cfg(all(not(feature = "full"), feature = "printing"))]
         impl ::quote::ToTokens for $name {
             fn to_tokens(&self, _: &mut ::proc_macro2::TokenStream) {
                 unreachable!()
             }
         }
     };
 
     (
         [$($attrs_pub:tt)*]
-        struct $name:ident #manual_extra_traits $($rest:tt)*
-    ) => {
-        #[cfg_attr(feature = "extra-traits", derive(Debug))]
-        #[cfg_attr(feature = "clone-impls", derive(Clone))]
-        $($attrs_pub)* struct $name $($rest)*
-    };
-
-    (
-        [$($attrs_pub:tt)*]
-        struct $name:ident #manual_extra_traits_debug $($rest:tt)*
-    ) => {
-        #[cfg_attr(feature = "clone-impls", derive(Clone))]
-        $($attrs_pub)* struct $name $($rest)*
-    };
-
-    (
-        [$($attrs_pub:tt)*]
         struct $name:ident $($rest:tt)*
     ) => {
-        #[cfg_attr(feature = "extra-traits", derive(Debug, Eq, PartialEq, Hash))]
-        #[cfg_attr(feature = "clone-impls", derive(Clone))]
         $($attrs_pub)* struct $name $($rest)*
     };
 
     ($($t:tt)*) => {
         strip_attrs_pub!(ast_struct!($($t)*));
     };
 }
 
@@ -60,29 +37,18 @@ macro_rules! ast_enum {
         [$($attrs_pub:tt)*]
         enum $name:ident #no_visit $($rest:tt)*
     ) => (
         ast_enum!([$($attrs_pub)*] enum $name $($rest)*);
     );
 
     (
         [$($attrs_pub:tt)*]
-        enum $name:ident #manual_extra_traits $($rest:tt)*
-    ) => (
-        #[cfg_attr(feature = "extra-traits", derive(Debug))]
-        #[cfg_attr(feature = "clone-impls", derive(Clone))]
-        $($attrs_pub)* enum $name $($rest)*
-    );
-
-    (
-        [$($attrs_pub:tt)*]
         enum $name:ident $($rest:tt)*
     ) => (
-        #[cfg_attr(feature = "extra-traits", derive(Debug, Eq, PartialEq, Hash))]
-        #[cfg_attr(feature = "clone-impls", derive(Clone))]
         $($attrs_pub)* enum $name $($rest)*
     );
 
     ($($t:tt)*) => {
         strip_attrs_pub!(ast_enum!($($t)*));
     };
 }
 
@@ -115,36 +81,43 @@ macro_rules! ast_enum_of_structs_impl {
             )*
         }
 
         $($remaining:tt)*
     ) => {
         check_keyword_matches!(pub $pub);
         check_keyword_matches!(enum $enum);
 
-        $(
-            $(
-                impl From<$member> for $name {
-                    fn from(e: $member) -> $name {
-                        $name::$variant(e)
-                    }
-                }
-            )*
-        )*
+        $($(
+            ast_enum_from_struct!($name::$variant, $member);
+        )*)*
 
         #[cfg(feature = "printing")]
         generate_to_tokens! {
             $($remaining)*
             ()
             tokens
             $name { $($variant $($member)*,)* }
         }
     };
 }
 
+macro_rules! ast_enum_from_struct {
+    // No From<TokenStream> for verbatim variants.
+    ($name:ident::Verbatim, $member:ident) => {};
+
+    ($name:ident::$variant:ident, $member:ident) => {
+        impl From<$member> for $name {
+            fn from(e: $member) -> $name {
+                $name::$variant(e)
+            }
+        }
+    };
+}
+
 #[cfg(feature = "printing")]
 macro_rules! generate_to_tokens {
     (do_not_generate_to_tokens $($foo:tt)*) => ();
 
     (($($arms:tt)*) $tokens:ident $name:ident { $variant:ident, $($next:tt)*}) => {
         generate_to_tokens!(
             ($($arms)* $name::$variant => {})
             $tokens $name { $($next)* }
diff --git a/third_party/rust/syn/src/op.rs b/third_party/rust/syn/src/op.rs
--- a/third_party/rust/syn/src/op.rs
+++ b/third_party/rust/syn/src/op.rs
@@ -1,14 +1,13 @@
 ast_enum! {
     /// A binary operator: `+`, `+=`, `&`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
-    #[cfg_attr(feature = "clone-impls", derive(Copy))]
     pub enum BinOp {
         /// The `+` operator (addition)
         Add(Token![+]),
         /// The `-` operator (subtraction)
         Sub(Token![-]),
         /// The `*` operator (multiplication)
         Mul(Token![*]),
         /// The `/` operator (division)
@@ -62,19 +61,18 @@ ast_enum! {
         /// The `>>=` operator
         ShrEq(Token![>>=]),
     }
 }
 
 ast_enum! {
     /// A unary operator: `*`, `!`, `-`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
-    #[cfg_attr(feature = "clone-impls", derive(Copy))]
     pub enum UnOp {
         /// The `*` operator for dereferencing
         Deref(Token![*]),
         /// The `!` operator for logical inversion
         Not(Token![!]),
         /// The `-` operator for negation
         Neg(Token![-]),
     }
diff --git a/third_party/rust/syn/src/parse.rs b/third_party/rust/syn/src/parse.rs
--- a/third_party/rust/syn/src/parse.rs
+++ b/third_party/rust/syn/src/parse.rs
@@ -21,18 +21,18 @@
 //! procedural macro through [`parse_macro_input!`] as shown at the bottom of
 //! the snippet. If the caller provides syntactically invalid input to the
 //! procedural macro, they will receive a helpful compiler error message
 //! pointing out the exact token that triggered the failure to parse.
 //!
 //! [`parse_macro_input!`]: ../macro.parse_macro_input.html
 //!
 //! ```
-//! extern crate proc_macro;
-//!
+//! # extern crate proc_macro;
+//! #
 //! use proc_macro::TokenStream;
 //! use syn::{braced, parse_macro_input, token, Field, Ident, Result, Token};
 //! use syn::parse::{Parse, ParseStream};
 //! use syn::punctuated::Punctuated;
 //!
 //! enum Item {
 //!     Struct(ItemStruct),
 //!     Enum(ItemEnum),
@@ -104,19 +104,17 @@
 //! ```
 //! use syn::Type;
 //!
 //! # fn run_parser() -> syn::Result<()> {
 //! let t: Type = syn::parse_str("std::collections::HashMap<String, Value>")?;
 //! #     Ok(())
 //! # }
 //! #
-//! # fn main() {
-//! #     run_parser().unwrap();
-//! # }
+//! # run_parser().unwrap();
 //! ```
 //!
 //! The [`parse_quote!`] macro also uses this approach.
 //!
 //! [`parse_quote!`]: ../macro.parse_quote.html
 //!
 //! # The `Parser` trait
 //!
@@ -150,18 +148,18 @@
 //!
 //! In these cases the types provide a choice of parser functions rather than a
 //! single `Parse` implementation, and those parser functions can be invoked
 //! through the [`Parser`] trait.
 //!
 //! [`Parser`]: trait.Parser.html
 //!
 //! ```
-//! extern crate proc_macro;
-//!
+//! # extern crate proc_macro;
+//! #
 //! use proc_macro::TokenStream;
 //! use syn::parse::Parser;
 //! use syn::punctuated::Punctuated;
 //! use syn::{Attribute, Expr, PathSegment, Result, Token};
 //!
 //! fn call_some_parser_methods(input: TokenStream) -> Result<()> {
 //!     // Parse a nonempty sequence of path segments separated by `::` punctuation
 //!     // with no trailing punctuation.
@@ -181,17 +179,17 @@
 //!     let _attrs = parser.parse(tokens)?;
 //!
 //!     Ok(())
 //! }
 //! ```
 //!
 //! ---
 //!
-//! *This module is available if Syn is built with the `"parsing"` feature.*
+//! *This module is available only if Syn is built with the `"parsing"` feature.*
 
 #[path = "discouraged.rs"]
 pub mod discouraged;
 
 use std::cell::Cell;
 use std::fmt::{self, Debug, Display};
 use std::marker::PhantomData;
 use std::mem;
@@ -212,16 +210,21 @@ use crate::lookahead;
 use crate::punctuated::Punctuated;
 use crate::token::Token;
 
 pub use crate::error::{Error, Result};
 pub use crate::lookahead::{Lookahead1, Peek};
 
 /// Parsing interface implemented by all types that can be parsed in a default
 /// way from a token stream.
+///
+/// Refer to the [module documentation] for details about implementing and using
+/// the `Parse` trait.
+///
+/// [module documentation]: self
 pub trait Parse: Sized {
     fn parse(input: ParseStream) -> Result<Self>;
 }
 
 /// Input to a Syn parser function.
 ///
 /// See the methods of this type under the documentation of [`ParseBuffer`]. For
 /// an overview of parsing in Syn, refer to the [module documentation].
@@ -258,23 +261,26 @@ pub struct ParseBuffer<'a> {
     // ParseBuffer<'a>, upcast to ParseBuffer<'short> for some lifetime shorter
     // than 'a, and then assign a Cursor<'short> into the Cell.
     //
     // By extension, it would not be safe to expose an API that accepts a
     // Cursor<'a> and trusts that it lives as long as the cursor currently in
     // the cell.
     cell: Cell<Cursor<'static>>,
     marker: PhantomData<Cursor<'a>>,
-    unexpected: Rc<Cell<Option<Span>>>,
+    unexpected: Cell<Option<Rc<Cell<Unexpected>>>>,
 }
 
 impl<'a> Drop for ParseBuffer<'a> {
     fn drop(&mut self) {
-        if !self.is_empty() && self.unexpected.get().is_none() {
-            self.unexpected.set(Some(self.cursor().span()));
+        if let Some(unexpected_span) = span_of_unexpected_ignoring_nones(self.cursor()) {
+            let (inner, old_span) = inner_unexpected(self);
+            if old_span.is_none() {
+                inner.set(Unexpected::Some(unexpected_span));
+            }
         }
     }
 }
 
 impl<'a> Display for ParseBuffer<'a> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         Display::fmt(&self.cursor().token_stream(), f)
     }
@@ -319,25 +325,22 @@ impl<'a> Debug for ParseBuffer<'a> {
 /// #
 /// # fn remainder_after_skipping_past_next_at(
 /// #     input: ParseStream,
 /// # ) -> Result<proc_macro2::TokenStream> {
 /// #     skip_past_next_at(input)?;
 /// #     input.parse()
 /// # }
 /// #
-/// # fn main() {
-/// #     use syn::parse::Parser;
-/// #     let remainder = remainder_after_skipping_past_next_at
-/// #         .parse_str("a @ b c")
-/// #         .unwrap();
-/// #     assert_eq!(remainder.to_string(), "b c");
-/// # }
+/// # use syn::parse::Parser;
+/// # let remainder = remainder_after_skipping_past_next_at
+/// #     .parse_str("a @ b c")
+/// #     .unwrap();
+/// # assert_eq!(remainder.to_string(), "b c");
 /// ```
-#[derive(Copy, Clone)]
 pub struct StepCursor<'c, 'a> {
     scope: Span,
     // This field is covariant in 'c.
     cursor: Cursor<'c>,
     // This field is contravariant in 'c. Together these make StepCursor
     // invariant in 'c. Also covariant in 'a. The user cannot cast 'c to a
     // different lifetime but can upcast into a StepCursor with a shorter
     // lifetime 'a.
@@ -351,16 +354,24 @@ pub struct StepCursor<'c, 'a> {
 impl<'c, 'a> Deref for StepCursor<'c, 'a> {
     type Target = Cursor<'c>;
 
     fn deref(&self) -> &Self::Target {
         &self.cursor
     }
 }
 
+impl<'c, 'a> Copy for StepCursor<'c, 'a> {}
+
+impl<'c, 'a> Clone for StepCursor<'c, 'a> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
 impl<'c, 'a> StepCursor<'c, 'a> {
     /// Triggers an error at the current position of the parse stream.
     ///
     /// The `ParseStream::step` invocation will return this same error without
     /// advancing the stream state.
     pub fn error<T: Display>(self, message: T) -> Error {
         error::new_at(self.scope, self.cursor, message)
     }
@@ -370,46 +381,91 @@ pub(crate) fn advance_step_cursor<'c, 'a
     // Refer to the comments within the StepCursor definition. We use the
     // fact that a StepCursor<'c, 'a> exists as proof that 'c outlives 'a.
     // Cursor is covariant in its lifetime parameter so we can cast a
     // Cursor<'c> to one with the shorter lifetime Cursor<'a>.
     let _ = proof;
     unsafe { mem::transmute::<Cursor<'c>, Cursor<'a>>(to) }
 }
 
-fn skip(input: ParseStream) -> bool {
-    input
-        .step(|cursor| {
-            if let Some((_lifetime, rest)) = cursor.lifetime() {
-                Ok((true, rest))
-            } else if let Some((_token, rest)) = cursor.token_tree() {
-                Ok((true, rest))
-            } else {
-                Ok((false, *cursor))
-            }
-        })
-        .unwrap()
-}
-
 pub(crate) fn new_parse_buffer(
     scope: Span,
     cursor: Cursor,
-    unexpected: Rc<Cell<Option<Span>>>,
+    unexpected: Rc<Cell<Unexpected>>,
 ) -> ParseBuffer {
     ParseBuffer {
         scope,
         // See comment on `cell` in the struct definition.
         cell: Cell::new(unsafe { mem::transmute::<Cursor, Cursor<'static>>(cursor) }),
         marker: PhantomData,
-        unexpected,
+        unexpected: Cell::new(Some(unexpected)),
+    }
+}
+
+pub(crate) enum Unexpected {
+    None,
+    Some(Span),
+    Chain(Rc<Cell<Unexpected>>),
+}
+
+impl Default for Unexpected {
+    fn default() -> Self {
+        Unexpected::None
+    }
+}
+
+impl Clone for Unexpected {
+    fn clone(&self) -> Self {
+        match self {
+            Unexpected::None => Unexpected::None,
+            Unexpected::Some(span) => Unexpected::Some(*span),
+            Unexpected::Chain(next) => Unexpected::Chain(next.clone()),
+        }
     }
 }
 
-pub(crate) fn get_unexpected(buffer: &ParseBuffer) -> Rc<Cell<Option<Span>>> {
-    buffer.unexpected.clone()
+// We call this on Cell<Unexpected> and Cell<Option<T>> where temporarily
+// swapping in a None is cheap.
+fn cell_clone<T: Default + Clone>(cell: &Cell<T>) -> T {
+    let prev = cell.take();
+    let ret = prev.clone();
+    cell.set(prev);
+    ret
+}
+
+fn inner_unexpected(buffer: &ParseBuffer) -> (Rc<Cell<Unexpected>>, Option<Span>) {
+    let mut unexpected = get_unexpected(buffer);
+    loop {
+        match cell_clone(&unexpected) {
+            Unexpected::None => return (unexpected, None),
+            Unexpected::Some(span) => return (unexpected, Some(span)),
+            Unexpected::Chain(next) => unexpected = next,
+        }
+    }
+}
+
+pub(crate) fn get_unexpected(buffer: &ParseBuffer) -> Rc<Cell<Unexpected>> {
+    cell_clone(&buffer.unexpected).unwrap()
+}
+
+fn span_of_unexpected_ignoring_nones(mut cursor: Cursor) -> Option<Span> {
+    if cursor.eof() {
+        return None;
+    }
+    while let Some((inner, _span, rest)) = cursor.group(Delimiter::None) {
+        if let Some(unexpected) = span_of_unexpected_ignoring_nones(inner) {
+            return Some(unexpected);
+        }
+        cursor = rest;
+    }
+    if cursor.eof() {
+        None
+    } else {
+        Some(cursor.span())
+    }
 }
 
 impl<'a> ParseBuffer<'a> {
     /// Parses a syntax tree node of type `T`, advancing the position of our
     /// parse stream past it.
     pub fn parse<T: Parse>(&self) -> Result<T> {
         T::parse(self)
     }
@@ -561,24 +617,27 @@ impl<'a> ParseBuffer<'a> {
     ///             input.parse().map(UnionOrMacro::Union)
     ///         } else {
     ///             input.parse().map(UnionOrMacro::Macro)
     ///         }
     ///     }
     /// }
     /// ```
     pub fn peek2<T: Peek>(&self, token: T) -> bool {
-        let ahead = self.fork();
-        skip(&ahead) && ahead.peek(token)
+        let _ = token;
+        self.cursor().skip().map_or(false, T::Token::peek)
     }
 
     /// Looks at the third-next token in the parse stream.
     pub fn peek3<T: Peek>(&self, token: T) -> bool {
-        let ahead = self.fork();
-        skip(&ahead) && skip(&ahead) && ahead.peek(token)
+        let _ = token;
+        self.cursor()
+            .skip()
+            .and_then(Cursor::skip)
+            .map_or(false, T::Token::peek)
     }
 
     /// Parses zero or more occurrences of `T` separated by punctuation of type
     /// `P`, with optional trailing punctuation.
     ///
     /// Parsing continues until the end of this parse stream. The entire content
     /// of this parse stream must consist of `T` and `P`.
     ///
@@ -610,22 +669,20 @@ impl<'a> ParseBuffer<'a> {
     ///             ident: input.parse()?,
     ///             paren_token: parenthesized!(content in input),
     ///             fields: content.parse_terminated(Type::parse)?,
     ///             semi_token: input.parse()?,
     ///         })
     ///     }
     /// }
     /// #
-    /// # fn main() {
-    /// #     let input = quote! {
-    /// #         struct S(A, B);
-    /// #     };
-    /// #     syn::parse2::<TupleStruct>(input).unwrap();
-    /// # }
+    /// # let input = quote! {
+    /// #     struct S(A, B);
+    /// # };
+    /// # syn::parse2::<TupleStruct>(input).unwrap();
     /// ```
     pub fn parse_terminated<T, P: Parse>(
         &self,
         parser: fn(ParseStream) -> Result<T>,
     ) -> Result<Punctuated<T, P>> {
         Punctuated::parse_terminated_with(self, parser)
     }
 
@@ -842,18 +899,18 @@ impl<'a> ParseBuffer<'a> {
     /// }
     /// ```
     pub fn fork(&self) -> Self {
         ParseBuffer {
             scope: self.scope,
             cell: self.cell.clone(),
             marker: PhantomData,
             // Not the parent's unexpected. Nothing cares whether the clone
-            // parses all the way.
-            unexpected: Rc::new(Cell::new(None)),
+            // parses all the way unless we `advance_to`.
+            unexpected: Cell::new(Some(Rc::new(Cell::new(Unexpected::None)))),
         }
     }
 
     /// Triggers an error at the current position of the parse stream.
     ///
     /// # Example
     ///
     /// ```
@@ -918,23 +975,21 @@ impl<'a> ParseBuffer<'a> {
     /// #
     /// # fn remainder_after_skipping_past_next_at(
     /// #     input: ParseStream,
     /// # ) -> Result<proc_macro2::TokenStream> {
     /// #     skip_past_next_at(input)?;
     /// #     input.parse()
     /// # }
     /// #
-    /// # fn main() {
-    /// #     use syn::parse::Parser;
-    /// #     let remainder = remainder_after_skipping_past_next_at
-    /// #         .parse_str("a @ b c")
-    /// #         .unwrap();
-    /// #     assert_eq!(remainder.to_string(), "b c");
-    /// # }
+    /// # use syn::parse::Parser;
+    /// # let remainder = remainder_after_skipping_past_next_at
+    /// #     .parse_str("a @ b c")
+    /// #     .unwrap();
+    /// # assert_eq!(remainder.to_string(), "b c");
     /// ```
     pub fn step<F, R>(&self, function: F) -> Result<R>
     where
         F: for<'c> FnOnce(StepCursor<'c, 'a>) -> Result<(R, Cursor<'c>)>,
     {
         // Since the user's function is required to work for any 'c, we know
         // that the Cursor<'c> they return is either derived from the input
         // StepCursor<'c, 'a> or from a Cursor<'static>.
@@ -956,27 +1011,39 @@ impl<'a> ParseBuffer<'a> {
             scope: self.scope,
             cursor: self.cell.get(),
             marker: PhantomData,
         })?;
         self.cell.set(rest);
         Ok(node)
     }
 
+    /// Returns the `Span` of the next token in the parse stream, or
+    /// `Span::call_site()` if this parse stream has completely exhausted its
+    /// input `TokenStream`.
+    pub fn span(&self) -> Span {
+        let cursor = self.cursor();
+        if cursor.eof() {
+            self.scope
+        } else {
+            crate::buffer::open_span_of_group(cursor)
+        }
+    }
+
     /// Provides low-level access to the token representation underlying this
     /// parse stream.
     ///
     /// Cursors are immutable so no operations you perform against the cursor
     /// will affect the state of this parse stream.
     pub fn cursor(&self) -> Cursor<'a> {
         self.cell.get()
     }
 
     fn check_unexpected(&self) -> Result<()> {
-        match self.unexpected.get() {
+        match inner_unexpected(self).1 {
             Some(span) => Err(Error::new(span, "unexpected token")),
             None => Ok(()),
         }
     }
 }
 
 impl<T: Parse> Parse for Box<T> {
     fn parse(input: ParseStream) -> Result<Self> {
@@ -1043,32 +1110,32 @@ impl Parse for Literal {
 }
 
 /// Parser that can parse Rust tokens into a particular syntax tree node.
 ///
 /// Refer to the [module documentation] for details about parsing in Syn.
 ///
 /// [module documentation]: self
 ///
-/// *This trait is available if Syn is built with the `"parsing"` feature.*
+/// *This trait is available only if Syn is built with the `"parsing"` feature.*
 pub trait Parser: Sized {
     type Output;
 
     /// Parse a proc-macro2 token stream into the chosen syntax tree node.
     ///
     /// This function will check that the input is fully parsed. If there are
     /// any unparsed tokens at the end of the stream, an error is returned.
     fn parse2(self, tokens: TokenStream) -> Result<Self::Output>;
 
     /// Parse tokens of source code into the chosen syntax tree node.
     ///
     /// This function will check that the input is fully parsed. If there are
     /// any unparsed tokens at the end of the stream, an error is returned.
     ///
-    /// *This method is available if Syn is built with both the `"parsing"` and
+    /// *This method is available only if Syn is built with both the `"parsing"` and
     /// `"proc-macro"` features.*
     #[cfg(all(
         not(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "wasi"))),
         feature = "proc-macro"
     ))]
     fn parse(self, tokens: proc_macro::TokenStream) -> Result<Self::Output> {
         self.parse2(proc_macro2::TokenStream::from(tokens))
     }
@@ -1083,90 +1150,96 @@ pub trait Parser: Sized {
     /// Every span in the resulting syntax tree will be set to resolve at the
     /// macro call site.
     fn parse_str(self, s: &str) -> Result<Self::Output> {
         self.parse2(proc_macro2::TokenStream::from_str(s)?)
     }
 
     // Not public API.
     #[doc(hidden)]
+    #[cfg(any(feature = "full", feature = "derive"))]
     fn __parse_scoped(self, scope: Span, tokens: TokenStream) -> Result<Self::Output> {
         let _ = scope;
         self.parse2(tokens)
     }
 
     // Not public API.
     #[doc(hidden)]
+    #[cfg(any(feature = "full", feature = "derive"))]
     fn __parse_stream(self, input: ParseStream) -> Result<Self::Output> {
         input.parse().and_then(|tokens| self.parse2(tokens))
     }
 }
 
 fn tokens_to_parse_buffer(tokens: &TokenBuffer) -> ParseBuffer {
     let scope = Span::call_site();
     let cursor = tokens.begin();
-    let unexpected = Rc::new(Cell::new(None));
+    let unexpected = Rc::new(Cell::new(Unexpected::None));
     new_parse_buffer(scope, cursor, unexpected)
 }
 
 impl<F, T> Parser for F
 where
     F: FnOnce(ParseStream) -> Result<T>,
 {
     type Output = T;
 
     fn parse2(self, tokens: TokenStream) -> Result<T> {
         let buf = TokenBuffer::new2(tokens);
         let state = tokens_to_parse_buffer(&buf);
         let node = self(&state)?;
         state.check_unexpected()?;
-        if state.is_empty() {
+        if let Some(unexpected_span) = span_of_unexpected_ignoring_nones(state.cursor()) {
+            Err(Error::new(unexpected_span, "unexpected token"))
+        } else {
             Ok(node)
-        } else {
-            Err(state.error("unexpected token"))
         }
     }
 
     #[doc(hidden)]
+    #[cfg(any(feature = "full", feature = "derive"))]
     fn __parse_scoped(self, scope: Span, tokens: TokenStream) -> Result<Self::Output> {
         let buf = TokenBuffer::new2(tokens);
         let cursor = buf.begin();
-        let unexpected = Rc::new(Cell::new(None));
+        let unexpected = Rc::new(Cell::new(Unexpected::None));
         let state = new_parse_buffer(scope, cursor, unexpected);
         let node = self(&state)?;
         state.check_unexpected()?;
-        if state.is_empty() {
+        if let Some(unexpected_span) = span_of_unexpected_ignoring_nones(state.cursor()) {
+            Err(Error::new(unexpected_span, "unexpected token"))
+        } else {
             Ok(node)
-        } else {
-            Err(state.error("unexpected token"))
         }
     }
 
     #[doc(hidden)]
+    #[cfg(any(feature = "full", feature = "derive"))]
     fn __parse_stream(self, input: ParseStream) -> Result<Self::Output> {
         self(input)
     }
 }
 
+#[cfg(any(feature = "full", feature = "derive"))]
 pub(crate) fn parse_scoped<F: Parser>(f: F, scope: Span, tokens: TokenStream) -> Result<F::Output> {
     f.__parse_scoped(scope, tokens)
 }
 
+#[cfg(any(feature = "full", feature = "derive"))]
 pub(crate) fn parse_stream<F: Parser>(f: F, input: ParseStream) -> Result<F::Output> {
     f.__parse_stream(input)
 }
 
 /// An empty syntax tree node that consumes no tokens when parsed.
 ///
 /// This is useful for attribute macros that want to ensure they are not
 /// provided any attribute args.
 ///
 /// ```
-/// extern crate proc_macro;
-///
+/// # extern crate proc_macro;
+/// #
 /// use proc_macro::TokenStream;
 /// use syn::parse_macro_input;
 /// use syn::parse::Nothing;
 ///
 /// # const IGNORE: &str = stringify! {
 /// #[proc_macro_attribute]
 /// # };
 /// pub fn my_attr(args: TokenStream, input: TokenStream) -> TokenStream {
diff --git a/third_party/rust/syn/src/parse_macro_input.rs b/third_party/rust/syn/src/parse_macro_input.rs
--- a/third_party/rust/syn/src/parse_macro_input.rs
+++ b/third_party/rust/syn/src/parse_macro_input.rs
@@ -11,18 +11,18 @@
 /// # Intended usage
 ///
 /// This macro must be called from a function that returns
 /// `proc_macro::TokenStream`. Usually this will be your proc macro entry point,
 /// the function that has the #\[proc_macro\] / #\[proc_macro_derive\] /
 /// #\[proc_macro_attribute\] attribute.
 ///
 /// ```
-/// extern crate proc_macro;
-///
+/// # extern crate proc_macro;
+/// #
 /// use proc_macro::TokenStream;
 /// use syn::{parse_macro_input, Result};
 /// use syn::parse::{Parse, ParseStream};
 ///
 /// struct MyMacroInput {
 ///     /* ... */
 /// }
 ///
@@ -38,28 +38,52 @@
 /// # };
 /// pub fn my_macro(tokens: TokenStream) -> TokenStream {
 ///     let input = parse_macro_input!(tokens as MyMacroInput);
 ///
 ///     /* ... */
 /// #   "".parse().unwrap()
 /// }
 /// ```
-#[macro_export(local_inner_macros)]
+///
+/// <br>
+///
+/// # Expansion
+///
+/// `parse_macro_input!($variable as $Type)` expands to something like:
+///
+/// ```no_run
+/// # extern crate proc_macro;
+/// #
+/// # macro_rules! doc_test {
+/// #     ($variable:ident as $Type:ty) => {
+/// match syn::parse::<$Type>($variable) {
+///     Ok(syntax_tree) => syntax_tree,
+///     Err(err) => return proc_macro::TokenStream::from(err.to_compile_error()),
+/// }
+/// #     };
+/// # }
+/// #
+/// # fn test(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+/// #     let _ = doc_test!(input as syn::Ident);
+/// #     proc_macro::TokenStream::new()
+/// # }
+/// ```
+#[macro_export]
 macro_rules! parse_macro_input {
     ($tokenstream:ident as $ty:ty) => {
         match $crate::parse_macro_input::parse::<$ty>($tokenstream) {
             $crate::export::Ok(data) => data,
             $crate::export::Err(err) => {
                 return $crate::export::TokenStream::from(err.to_compile_error());
             }
         }
     };
     ($tokenstream:ident) => {
-        parse_macro_input!($tokenstream as _)
+        $crate::parse_macro_input!($tokenstream as _)
     };
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // Can parse any type that implements Parse.
 
 use crate::parse::{Parse, ParseStream, Parser, Result};
 use proc_macro::TokenStream;
diff --git a/third_party/rust/syn/src/parse_quote.rs b/third_party/rust/syn/src/parse_quote.rs
--- a/third_party/rust/syn/src/parse_quote.rs
+++ b/third_party/rust/syn/src/parse_quote.rs
@@ -19,17 +19,17 @@
 ///     let stmt: Stmt = parse_quote! {
 ///         let #name: #ty = Default::default();
 ///     };
 ///
 ///     println!("{:#?}", stmt);
 /// }
 /// ```
 ///
-/// *This macro is available if Syn is built with the `"parsing"` feature,
+/// *This macro is available only if Syn is built with the `"parsing"` feature,
 /// although interpolation of syntax tree nodes into the quoted tokens is only
 /// supported if Syn is built with the `"printing"` feature as well.*
 ///
 /// # Example
 ///
 /// The following helper function adds a bound `T: HeapSize` to every type
 /// parameter `T` in the input generics.
 ///
@@ -51,28 +51,30 @@
 ///
 /// This macro can parse the following additional types as a special case even
 /// though they do not implement the `Parse` trait.
 ///
 /// - [`Attribute`] — parses one attribute, allowing either outer like `#[...]`
 ///   or inner like `#![...]`
 /// - [`Punctuated<T, P>`] — parses zero or more `T` separated by punctuation
 ///   `P` with optional trailing punctuation
+/// - [`Vec<Stmt>`] — parses the same as `Block::parse_within`
 ///
 /// [`Punctuated<T, P>`]: punctuated::Punctuated
+/// [`Vec<Stmt>`]: Block::parse_within
 ///
 /// # Panics
 ///
 /// Panics if the tokens fail to parse as the expected syntax tree type. The
 /// caller is responsible for ensuring that the input tokens are syntactically
 /// valid.
 //
 // TODO: allow Punctuated to be inferred as intra doc link, currently blocked on
 // https://github.com/rust-lang/rust/issues/62834
-#[macro_export(local_inner_macros)]
+#[macro_export]
 macro_rules! parse_quote {
     ($($tt:tt)*) => {
         $crate::parse_quote::parse(
             $crate::export::From::from(
                 $crate::export::quote::quote!($($tt)*)
             )
         )
     };
@@ -107,16 +109,18 @@ impl<T: Parse> ParseQuote for T {
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // Any other types that we want `parse_quote!` to be able to parse.
 
 use crate::punctuated::Punctuated;
 #[cfg(any(feature = "full", feature = "derive"))]
 use crate::{attr, Attribute};
+#[cfg(feature = "full")]
+use crate::{Block, Stmt};
 
 #[cfg(any(feature = "full", feature = "derive"))]
 impl ParseQuote for Attribute {
     fn parse(input: ParseStream) -> Result<Self> {
         if input.peek(Token![#]) && input.peek2(Token![!]) {
             attr::parsing::single_parse_inner(input)
         } else {
             attr::parsing::single_parse_outer(input)
@@ -124,8 +128,15 @@ impl ParseQuote for Attribute {
     }
 }
 
 impl<T: Parse, P: Parse> ParseQuote for Punctuated<T, P> {
     fn parse(input: ParseStream) -> Result<Self> {
         Self::parse_terminated(input)
     }
 }
+
+#[cfg(feature = "full")]
+impl ParseQuote for Vec<Stmt> {
+    fn parse(input: ParseStream) -> Result<Self> {
+        Block::parse_within(input)
+    }
+}
diff --git a/third_party/rust/syn/src/pat.rs b/third_party/rust/syn/src/pat.rs
--- a/third_party/rust/syn/src/pat.rs
+++ b/third_party/rust/syn/src/pat.rs
@@ -1,31 +1,27 @@
 use super::*;
 use crate::punctuated::Punctuated;
-#[cfg(feature = "extra-traits")]
-use crate::tt::TokenStreamHelper;
 use proc_macro2::TokenStream;
-#[cfg(feature = "extra-traits")]
-use std::hash::{Hash, Hasher};
 
 ast_enum_of_structs! {
     /// A pattern in a local binding, function signature, match expression, or
     /// various other places.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     ///
     /// # Syntax tree enum
     ///
     /// This type is a [syntax tree enum].
     ///
     /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums
     //
     // TODO: change syntax-tree-enum link to an intra rustdoc link, currently
     // blocked on https://github.com/rust-lang/rust/issues/62833
-    pub enum Pat #manual_extra_traits {
+    pub enum Pat {
         /// A box pattern: `box v`.
         Box(PatBox),
 
         /// A pattern that binds a new variable: `ref mut binding @ SUBPATTERN`.
         Ident(PatIdent),
 
         /// A literal pattern: `0`.
         ///
@@ -81,321 +77,219 @@ ast_enum_of_structs! {
         #[doc(hidden)]
         __Nonexhaustive,
     }
 }
 
 ast_struct! {
     /// A box pattern: `box v`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct PatBox {
         pub attrs: Vec<Attribute>,
         pub box_token: Token![box],
         pub pat: Box<Pat>,
     }
 }
 
 ast_struct! {
     /// A pattern that binds a new variable: `ref mut binding @ SUBPATTERN`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// It may also be a unit struct or struct variant (e.g. `None`), or a
+    /// constant; these cannot be distinguished syntactically.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct PatIdent {
         pub attrs: Vec<Attribute>,
         pub by_ref: Option<Token![ref]>,
         pub mutability: Option<Token![mut]>,
         pub ident: Ident,
         pub subpat: Option<(Token![@], Box<Pat>)>,
     }
 }
 
 ast_struct! {
     /// A literal pattern: `0`.
     ///
     /// This holds an `Expr` rather than a `Lit` because negative numbers
     /// are represented as an `Expr::Unary`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct PatLit {
         pub attrs: Vec<Attribute>,
         pub expr: Box<Expr>,
     }
 }
 
 ast_struct! {
     /// A macro in pattern position.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct PatMacro {
         pub attrs: Vec<Attribute>,
         pub mac: Macro,
     }
 }
 
 ast_struct! {
     /// A pattern that matches any one of a set of cases.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct PatOr {
         pub attrs: Vec<Attribute>,
         pub leading_vert: Option<Token![|]>,
         pub cases: Punctuated<Pat, Token![|]>,
     }
 }
 
 ast_struct! {
     /// A path pattern like `Color::Red`, optionally qualified with a
     /// self-type.
     ///
     /// Unqualified path patterns can legally refer to variants, structs,
     /// constants or associated constants. Qualified path patterns like
     /// `<A>::B::C` and `<A as Trait>::B::C` can only legally refer to
     /// associated constants.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct PatPath {
         pub attrs: Vec<Attribute>,
         pub qself: Option<QSelf>,
         pub path: Path,
     }
 }
 
 ast_struct! {
     /// A range pattern: `1..=2`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct PatRange {
         pub attrs: Vec<Attribute>,
         pub lo: Box<Expr>,
         pub limits: RangeLimits,
         pub hi: Box<Expr>,
     }
 }
 
 ast_struct! {
     /// A reference pattern: `&mut var`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct PatReference {
         pub attrs: Vec<Attribute>,
         pub and_token: Token![&],
         pub mutability: Option<Token![mut]>,
         pub pat: Box<Pat>,
     }
 }
 
 ast_struct! {
     /// The dots in a tuple or slice pattern: `[0, 1, ..]`
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct PatRest {
         pub attrs: Vec<Attribute>,
         pub dot2_token: Token![..],
     }
 }
 
 ast_struct! {
     /// A dynamically sized slice pattern: `[a, b, ref i @ .., y, z]`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct PatSlice {
         pub attrs: Vec<Attribute>,
         pub bracket_token: token::Bracket,
         pub elems: Punctuated<Pat, Token![,]>,
     }
 }
 
 ast_struct! {
     /// A struct or struct variant pattern: `Variant { x, y, .. }`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct PatStruct {
         pub attrs: Vec<Attribute>,
         pub path: Path,
         pub brace_token: token::Brace,
         pub fields: Punctuated<FieldPat, Token![,]>,
         pub dot2_token: Option<Token![..]>,
     }
 }
 
 ast_struct! {
     /// A tuple pattern: `(a, b)`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct PatTuple {
         pub attrs: Vec<Attribute>,
         pub paren_token: token::Paren,
         pub elems: Punctuated<Pat, Token![,]>,
     }
 }
 
 ast_struct! {
     /// A tuple struct or tuple variant pattern: `Variant(x, y, .., z)`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct PatTupleStruct {
         pub attrs: Vec<Attribute>,
         pub path: Path,
         pub pat: PatTuple,
     }
 }
 
 ast_struct! {
     /// A type ascription pattern: `foo: f64`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct PatType {
         pub attrs: Vec<Attribute>,
         pub pat: Box<Pat>,
         pub colon_token: Token![:],
         pub ty: Box<Type>,
     }
 }
 
 ast_struct! {
     /// A pattern that matches any value: `_`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct PatWild {
         pub attrs: Vec<Attribute>,
         pub underscore_token: Token![_],
     }
 }
 
 ast_struct! {
     /// A single field in a struct pattern.
     ///
     /// Patterns like the fields of Foo `{ x, ref y, ref mut z }` are treated
     /// the same as `x: x, y: ref y, z: ref mut z` but there is no colon token.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct FieldPat {
         pub attrs: Vec<Attribute>,
         pub member: Member,
         pub colon_token: Option<Token![:]>,
         pub pat: Box<Pat>,
     }
 }
 
-#[cfg(feature = "extra-traits")]
-impl Eq for Pat {}
-
-#[cfg(feature = "extra-traits")]
-impl PartialEq for Pat {
-    fn eq(&self, other: &Self) -> bool {
-        match (self, other) {
-            (Pat::Box(this), Pat::Box(other)) => this == other,
-            (Pat::Ident(this), Pat::Ident(other)) => this == other,
-            (Pat::Lit(this), Pat::Lit(other)) => this == other,
-            (Pat::Macro(this), Pat::Macro(other)) => this == other,
-            (Pat::Or(this), Pat::Or(other)) => this == other,
-            (Pat::Path(this), Pat::Path(other)) => this == other,
-            (Pat::Range(this), Pat::Range(other)) => this == other,
-            (Pat::Reference(this), Pat::Reference(other)) => this == other,
-            (Pat::Rest(this), Pat::Rest(other)) => this == other,
-            (Pat::Slice(this), Pat::Slice(other)) => this == other,
-            (Pat::Struct(this), Pat::Struct(other)) => this == other,
-            (Pat::Tuple(this), Pat::Tuple(other)) => this == other,
-            (Pat::TupleStruct(this), Pat::TupleStruct(other)) => this == other,
-            (Pat::Type(this), Pat::Type(other)) => this == other,
-            (Pat::Verbatim(this), Pat::Verbatim(other)) => {
-                TokenStreamHelper(this) == TokenStreamHelper(other)
-            }
-            (Pat::Wild(this), Pat::Wild(other)) => this == other,
-            _ => false,
-        }
-    }
-}
-
-#[cfg(feature = "extra-traits")]
-impl Hash for Pat {
-    fn hash<H>(&self, hash: &mut H)
-    where
-        H: Hasher,
-    {
-        match self {
-            Pat::Box(pat) => {
-                hash.write_u8(0);
-                pat.hash(hash);
-            }
-            Pat::Ident(pat) => {
-                hash.write_u8(1);
-                pat.hash(hash);
-            }
-            Pat::Lit(pat) => {
-                hash.write_u8(2);
-                pat.hash(hash);
-            }
-            Pat::Macro(pat) => {
-                hash.write_u8(3);
-                pat.hash(hash);
-            }
-            Pat::Or(pat) => {
-                hash.write_u8(4);
-                pat.hash(hash);
-            }
-            Pat::Path(pat) => {
-                hash.write_u8(5);
-                pat.hash(hash);
-            }
-            Pat::Range(pat) => {
-                hash.write_u8(6);
-                pat.hash(hash);
-            }
-            Pat::Reference(pat) => {
-                hash.write_u8(7);
-                pat.hash(hash);
-            }
-            Pat::Rest(pat) => {
-                hash.write_u8(8);
-                pat.hash(hash);
-            }
-            Pat::Slice(pat) => {
-                hash.write_u8(9);
-                pat.hash(hash);
-            }
-            Pat::Struct(pat) => {
-                hash.write_u8(10);
-                pat.hash(hash);
-            }
-            Pat::Tuple(pat) => {
-                hash.write_u8(11);
-                pat.hash(hash);
-            }
-            Pat::TupleStruct(pat) => {
-                hash.write_u8(12);
-                pat.hash(hash);
-            }
-            Pat::Type(pat) => {
-                hash.write_u8(13);
-                pat.hash(hash);
-            }
-            Pat::Verbatim(pat) => {
-                hash.write_u8(14);
-                TokenStreamHelper(pat).hash(hash);
-            }
-            Pat::Wild(pat) => {
-                hash.write_u8(15);
-                pat.hash(hash);
-            }
-            Pat::__Nonexhaustive => unreachable!(),
-        }
-    }
-}
-
 #[cfg(feature = "parsing")]
-mod parsing {
+pub mod parsing {
     use super::*;
 
     use crate::ext::IdentExt;
-    use crate::parse::{Parse, ParseStream, Result};
+    use crate::parse::{Parse, ParseBuffer, ParseStream, Result};
     use crate::path;
 
     impl Parse for Pat {
         fn parse(input: ParseStream) -> Result<Self> {
+            let begin = input.fork();
             let lookahead = input.lookahead1();
             if lookahead.peek(Ident)
                 && ({
                     input.peek2(Token![::])
                         || input.peek2(Token![!])
                         || input.peek2(token::Brace)
                         || input.peek2(token::Paren)
                         || input.peek2(Token![..])
@@ -406,17 +300,16 @@ mod parsing {
                                 ahead.is_empty() || ahead.peek(Token![,])
                             }
                 })
                 || input.peek(Token![self]) && input.peek2(Token![::])
                 || lookahead.peek(Token![::])
                 || lookahead.peek(Token![<])
                 || input.peek(Token![Self])
                 || input.peek(Token![super])
-                || input.peek(Token![extern])
                 || input.peek(Token![crate])
             {
                 pat_path_or_macro_or_struct_or_range(input)
             } else if lookahead.peek(Token![_]) {
                 input.call(pat_wild).map(Pat::Wild)
             } else if input.peek(Token![box]) {
                 input.call(pat_box).map(Pat::Box)
             } else if input.peek(Token![-]) || lookahead.peek(Lit) {
@@ -429,28 +322,29 @@ mod parsing {
                 input.call(pat_ident).map(Pat::Ident)
             } else if lookahead.peek(Token![&]) {
                 input.call(pat_reference).map(Pat::Reference)
             } else if lookahead.peek(token::Paren) {
                 input.call(pat_tuple).map(Pat::Tuple)
             } else if lookahead.peek(token::Bracket) {
                 input.call(pat_slice).map(Pat::Slice)
             } else if lookahead.peek(Token![..]) && !input.peek(Token![...]) {
-                input.call(pat_rest).map(Pat::Rest)
+                pat_range_half_open(input, begin)
             } else {
                 Err(lookahead.error())
             }
         }
     }
 
     fn pat_path_or_macro_or_struct_or_range(input: ParseStream) -> Result<Pat> {
+        let begin = input.fork();
         let (qself, path) = path::parsing::qpath(input, true)?;
 
         if input.peek(Token![..]) {
-            return pat_range(input, qself, path).map(Pat::Range);
+            return pat_range(input, begin, qself, path);
         }
 
         if qself.is_some() {
             return Ok(Pat::Path(PatPath {
                 attrs: Vec::new(),
                 qself,
                 path,
             }));
@@ -482,17 +376,17 @@ mod parsing {
             }
         }
 
         if input.peek(token::Brace) {
             pat_struct(input, path).map(Pat::Struct)
         } else if input.peek(token::Paren) {
             pat_tuple_struct(input, path).map(Pat::TupleStruct)
         } else if input.peek(Token![..]) {
-            pat_range(input, qself, path).map(Pat::Range)
+            pat_range(input, begin, qself, path)
         } else {
             Ok(Pat::Path(PatPath {
                 attrs: Vec::new(),
                 qself,
                 path,
             }))
         }
     }
@@ -541,17 +435,17 @@ mod parsing {
     fn pat_struct(input: ParseStream, path: Path) -> Result<PatStruct> {
         let content;
         let brace_token = braced!(content in input);
 
         let mut fields = Punctuated::new();
         while !content.is_empty() && !content.peek(Token![..]) {
             let value = content.call(field_pat)?;
             fields.push_value(value);
-            if !content.peek(Token![,]) {
+            if content.is_empty() {
                 break;
             }
             let punct: Token![,] = content.parse()?;
             fields.push_punct(punct);
         }
 
         let dot2_token = if fields.empty_or_trailing() && content.peek(Token![..]) {
             Some(content.parse()?)
@@ -573,29 +467,30 @@ mod parsing {
             match *self {
                 Member::Named(_) => false,
                 Member::Unnamed(_) => true,
             }
         }
     }
 
     fn field_pat(input: ParseStream) -> Result<FieldPat> {
+        let attrs = input.call(Attribute::parse_outer)?;
         let boxed: Option<Token![box]> = input.parse()?;
         let by_ref: Option<Token![ref]> = input.parse()?;
         let mutability: Option<Token![mut]> = input.parse()?;
         let member: Member = input.parse()?;
 
         if boxed.is_none() && by_ref.is_none() && mutability.is_none() && input.peek(Token![:])
             || member.is_unnamed()
         {
             return Ok(FieldPat {
-                attrs: Vec::new(),
+                attrs,
                 member,
                 colon_token: input.parse()?,
-                pat: input.parse()?,
+                pat: Box::new(multi_pat(input)?),
             });
         }
 
         let ident = match member {
             Member::Named(ident) => ident,
             Member::Unnamed(_) => unreachable!(),
         };
 
@@ -605,49 +500,76 @@ mod parsing {
             mutability,
             ident: ident.clone(),
             subpat: None,
         });
 
         if let Some(boxed) = boxed {
             pat = Pat::Box(PatBox {
                 attrs: Vec::new(),
+                box_token: boxed,
                 pat: Box::new(pat),
-                box_token: boxed,
             });
         }
 
         Ok(FieldPat {
+            attrs,
             member: Member::Named(ident),
+            colon_token: None,
             pat: Box::new(pat),
-            attrs: Vec::new(),
-            colon_token: None,
         })
     }
 
-    fn pat_range(input: ParseStream, qself: Option<QSelf>, path: Path) -> Result<PatRange> {
-        Ok(PatRange {
-            attrs: Vec::new(),
-            lo: Box::new(Expr::Path(ExprPath {
+    fn pat_range(
+        input: ParseStream,
+        begin: ParseBuffer,
+        qself: Option<QSelf>,
+        path: Path,
+    ) -> Result<Pat> {
+        let limits: RangeLimits = input.parse()?;
+        let hi = input.call(pat_lit_expr)?;
+        if let Some(hi) = hi {
+            Ok(Pat::Range(PatRange {
                 attrs: Vec::new(),
-                qself,
-                path,
-            })),
-            limits: input.parse()?,
-            hi: input.call(pat_lit_expr)?,
-        })
+                lo: Box::new(Expr::Path(ExprPath {
+                    attrs: Vec::new(),
+                    qself,
+                    path,
+                })),
+                limits,
+                hi,
+            }))
+        } else {
+            Ok(Pat::Verbatim(verbatim::between(begin, input)))
+        }
+    }
+
+    fn pat_range_half_open(input: ParseStream, begin: ParseBuffer) -> Result<Pat> {
+        let limits: RangeLimits = input.parse()?;
+        let hi = input.call(pat_lit_expr)?;
+        if hi.is_some() {
+            Ok(Pat::Verbatim(verbatim::between(begin, input)))
+        } else {
+            match limits {
+                RangeLimits::HalfOpen(dot2_token) => Ok(Pat::Rest(PatRest {
+                    attrs: Vec::new(),
+                    dot2_token,
+                })),
+                RangeLimits::Closed(_) => Err(input.error("expected range upper bound")),
+            }
+        }
     }
 
     fn pat_tuple(input: ParseStream) -> Result<PatTuple> {
         let content;
         let paren_token = parenthesized!(content in input);
 
         let mut elems = Punctuated::new();
         while !content.is_empty() {
-            let value: Pat = content.parse()?;
+            let value = multi_pat(&content)?;
             elems.push_value(value);
             if content.is_empty() {
                 break;
             }
             let punct = content.parse()?;
             elems.push_punct(punct);
         }
 
@@ -663,225 +585,280 @@ mod parsing {
             attrs: Vec::new(),
             and_token: input.parse()?,
             mutability: input.parse()?,
             pat: input.parse()?,
         })
     }
 
     fn pat_lit_or_range(input: ParseStream) -> Result<Pat> {
-        let lo = input.call(pat_lit_expr)?;
+        let begin = input.fork();
+        let lo = input.call(pat_lit_expr)?.unwrap();
         if input.peek(Token![..]) {
-            Ok(Pat::Range(PatRange {
-                attrs: Vec::new(),
-                lo,
-                limits: input.parse()?,
-                hi: input.call(pat_lit_expr)?,
-            }))
+            let limits: RangeLimits = input.parse()?;
+            let hi = input.call(pat_lit_expr)?;
+            if let Some(hi) = hi {
+                Ok(Pat::Range(PatRange {
+                    attrs: Vec::new(),
+                    lo,
+                    limits,
+                    hi,
+                }))
+            } else {
+                Ok(Pat::Verbatim(verbatim::between(begin, input)))
+            }
         } else {
             Ok(Pat::Lit(PatLit {
                 attrs: Vec::new(),
                 expr: lo,
             }))
         }
     }
 
-    fn pat_lit_expr(input: ParseStream) -> Result<Box<Expr>> {
+    fn pat_lit_expr(input: ParseStream) -> Result<Option<Box<Expr>>> {
+        if input.is_empty()
+            || input.peek(Token![|])
+            || input.peek(Token![=>])
+            || input.peek(Token![:]) && !input.peek(Token![::])
+            || input.peek(Token![,])
+            || input.peek(Token![;])
+        {
+            return Ok(None);
+        }
+
         let neg: Option<Token![-]> = input.parse()?;
 
         let lookahead = input.lookahead1();
         let expr = if lookahead.peek(Lit) {
             Expr::Lit(input.parse()?)
         } else if lookahead.peek(Ident)
             || lookahead.peek(Token![::])
             || lookahead.peek(Token![<])
             || lookahead.peek(Token![self])
             || lookahead.peek(Token![Self])
             || lookahead.peek(Token![super])
-            || lookahead.peek(Token![extern])
             || lookahead.peek(Token![crate])
         {
             Expr::Path(input.parse()?)
         } else {
             return Err(lookahead.error());
         };
 
-        Ok(Box::new(if let Some(neg) = neg {
+        Ok(Some(Box::new(if let Some(neg) = neg {
             Expr::Unary(ExprUnary {
                 attrs: Vec::new(),
                 op: UnOp::Neg(neg),
                 expr: Box::new(expr),
             })
         } else {
             expr
-        }))
+        })))
     }
 
     fn pat_slice(input: ParseStream) -> Result<PatSlice> {
         let content;
         let bracket_token = bracketed!(content in input);
 
         let mut elems = Punctuated::new();
         while !content.is_empty() {
-            let value: Pat = content.parse()?;
+            let value = multi_pat(&content)?;
             elems.push_value(value);
             if content.is_empty() {
                 break;
             }
             let punct = content.parse()?;
             elems.push_punct(punct);
         }
 
         Ok(PatSlice {
             attrs: Vec::new(),
             bracket_token,
             elems,
         })
     }
 
-    fn pat_rest(input: ParseStream) -> Result<PatRest> {
-        Ok(PatRest {
-            attrs: Vec::new(),
-            dot2_token: input.parse()?,
-        })
+    pub fn multi_pat(input: ParseStream) -> Result<Pat> {
+        multi_pat_impl(input, None)
+    }
+
+    pub fn multi_pat_with_leading_vert(input: ParseStream) -> Result<Pat> {
+        let leading_vert: Option<Token![|]> = input.parse()?;
+        multi_pat_impl(input, leading_vert)
+    }
+
+    fn multi_pat_impl(input: ParseStream, leading_vert: Option<Token![|]>) -> Result<Pat> {
+        let mut pat: Pat = input.parse()?;
+        if leading_vert.is_some()
+            || input.peek(Token![|]) && !input.peek(Token![||]) && !input.peek(Token![|=])
+        {
+            let mut cases = Punctuated::new();
+            cases.push_value(pat);
+            while input.peek(Token![|]) && !input.peek(Token![||]) && !input.peek(Token![|=]) {
+                let punct = input.parse()?;
+                cases.push_punct(punct);
+                let pat: Pat = input.parse()?;
+                cases.push_value(pat);
+            }
+            pat = Pat::Or(PatOr {
+                attrs: Vec::new(),
+                leading_vert,
+                cases,
+            });
+        }
+        Ok(pat)
     }
 }
 
 #[cfg(feature = "printing")]
 mod printing {
     use super::*;
 
     use proc_macro2::TokenStream;
     use quote::{ToTokens, TokenStreamExt};
 
     use crate::attr::FilterAttrs;
 
     impl ToTokens for PatWild {
         fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
             self.underscore_token.to_tokens(tokens);
         }
     }
 
     impl ToTokens for PatIdent {
         fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
             self.by_ref.to_tokens(tokens);
             self.mutability.to_tokens(tokens);
             self.ident.to_tokens(tokens);
             if let Some((at_token, subpat)) = &self.subpat {
                 at_token.to_tokens(tokens);
                 subpat.to_tokens(tokens);
             }
         }
     }
 
     impl ToTokens for PatStruct {
         fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
             self.path.to_tokens(tokens);
             self.brace_token.surround(tokens, |tokens| {
                 self.fields.to_tokens(tokens);
                 // NOTE: We need a comma before the dot2 token if it is present.
                 if !self.fields.empty_or_trailing() && self.dot2_token.is_some() {
                     <Token![,]>::default().to_tokens(tokens);
                 }
                 self.dot2_token.to_tokens(tokens);
             });
         }
     }
 
     impl ToTokens for PatTupleStruct {
         fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
             self.path.to_tokens(tokens);
             self.pat.to_tokens(tokens);
         }
     }
 
     impl ToTokens for PatType {
         fn to_tokens(&self, tokens: &mut TokenStream) {
             tokens.append_all(self.attrs.outer());
             self.pat.to_tokens(tokens);
             self.colon_token.to_tokens(tokens);
             self.ty.to_tokens(tokens);
         }
     }
 
     impl ToTokens for PatPath {
         fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
             private::print_path(tokens, &self.qself, &self.path);
         }
     }
 
     impl ToTokens for PatTuple {
         fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
             self.paren_token.surround(tokens, |tokens| {
                 self.elems.to_tokens(tokens);
             });
         }
     }
 
     impl ToTokens for PatBox {
         fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
             self.box_token.to_tokens(tokens);
             self.pat.to_tokens(tokens);
         }
     }
 
     impl ToTokens for PatReference {
         fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
             self.and_token.to_tokens(tokens);
             self.mutability.to_tokens(tokens);
             self.pat.to_tokens(tokens);
         }
     }
 
     impl ToTokens for PatRest {
         fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
             self.dot2_token.to_tokens(tokens);
         }
     }
 
     impl ToTokens for PatLit {
         fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
             self.expr.to_tokens(tokens);
         }
     }
 
     impl ToTokens for PatRange {
         fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
             self.lo.to_tokens(tokens);
             match &self.limits {
                 RangeLimits::HalfOpen(t) => t.to_tokens(tokens),
                 RangeLimits::Closed(t) => t.to_tokens(tokens),
             }
             self.hi.to_tokens(tokens);
         }
     }
 
     impl ToTokens for PatSlice {
         fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
             self.bracket_token.surround(tokens, |tokens| {
                 self.elems.to_tokens(tokens);
             });
         }
     }
 
     impl ToTokens for PatMacro {
         fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
             self.mac.to_tokens(tokens);
         }
     }
 
     impl ToTokens for PatOr {
         fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
             self.leading_vert.to_tokens(tokens);
             self.cases.to_tokens(tokens);
         }
     }
 
     impl ToTokens for FieldPat {
         fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
             if let Some(colon_token) = &self.colon_token {
                 self.member.to_tokens(tokens);
                 colon_token.to_tokens(tokens);
             }
             self.pat.to_tokens(tokens);
         }
     }
 }
diff --git a/third_party/rust/syn/src/path.rs b/third_party/rust/syn/src/path.rs
--- a/third_party/rust/syn/src/path.rs
+++ b/third_party/rust/syn/src/path.rs
@@ -1,15 +1,15 @@
 use super::*;
 use crate::punctuated::Punctuated;
 
 ast_struct! {
-    /// A path at which a named item is exported: `std::collections::HashMap`.
+    /// A path at which a named item is exported (e.g. `std::collections::HashMap`).
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub struct Path {
         pub leading_colon: Option<Token![::]>,
         pub segments: Punctuated<PathSegment, Token![::]>,
     }
 }
 
 impl<T> From<T> for Path
@@ -24,17 +24,17 @@ where
         path.segments.push_value(segment.into());
         path
     }
 }
 
 ast_struct! {
     /// A segment of a path together with any path arguments on that segment.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub struct PathSegment {
         pub ident: Ident,
         pub arguments: PathArguments,
     }
 }
 
 impl<T> From<T> for PathSegment
@@ -47,17 +47,17 @@ where
             arguments: PathArguments::None,
         }
     }
 }
 
 ast_enum! {
     /// Angle bracketed or parenthesized arguments of a path segment.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     ///
     /// ## Angle bracketed
     ///
     /// The `<'a, T>` in `std::slice::iter<'a, T>`.
     ///
     /// ## Parenthesized
     ///
@@ -93,17 +93,17 @@ impl PathArguments {
             PathArguments::AngleBracketed(_) | PathArguments::Parenthesized(_) => false,
         }
     }
 }
 
 ast_enum! {
     /// An individual generic argument, like `'a`, `T`, or `Item = T`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub enum GenericArgument {
         /// A lifetime argument.
         Lifetime(Lifetime),
         /// A type argument.
         Type(Type),
         /// A binding (equality constraint) on an associated type: the `Item =
         /// u8` in `Iterator<Item = u8>`.
@@ -117,55 +117,55 @@ ast_enum! {
         Const(Expr),
     }
 }
 
 ast_struct! {
     /// Angle bracketed arguments of a path segment: the `<K, V>` in `HashMap<K,
     /// V>`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub struct AngleBracketedGenericArguments {
         pub colon2_token: Option<Token![::]>,
         pub lt_token: Token![<],
         pub args: Punctuated<GenericArgument, Token![,]>,
         pub gt_token: Token![>],
     }
 }
 
 ast_struct! {
     /// A binding (equality constraint) on an associated type: `Item = u8`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub struct Binding {
         pub ident: Ident,
         pub eq_token: Token![=],
         pub ty: Type,
     }
 }
 
 ast_struct! {
     /// An associated type bound: `Iterator<Item: Display>`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub struct Constraint {
         pub ident: Ident,
         pub colon_token: Token![:],
         pub bounds: Punctuated<TypeParamBound, Token![+]>,
     }
 }
 
 ast_struct! {
     /// Arguments of a function path segment: the `(A, B) -> C` in `Fn(A,B) ->
     /// C`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub struct ParenthesizedGenericArguments {
         pub paren_token: token::Paren,
         /// `(A, B)`
         pub inputs: Punctuated<Type, Token![,]>,
         /// `C`
         pub output: ReturnType,
     }
@@ -184,17 +184,17 @@ ast_struct! {
     ///  ^~~~~~    ~~~~~~~~~~~~~~^
     ///  ty        position = 3
     ///
     /// <Vec<T>>::AssociatedItem
     ///  ^~~~~~   ^
     ///  ty       position = 0
     /// ```
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub struct QSelf {
         pub lt_token: Token![<],
         pub ty: Box<Type>,
         pub position: usize,
         pub as_token: Option<Token![as]>,
         pub gt_token: Token![>],
     }
@@ -286,21 +286,17 @@ pub mod parsing {
     impl Parse for PathSegment {
         fn parse(input: ParseStream) -> Result<Self> {
             Self::parse_helper(input, false)
         }
     }
 
     impl PathSegment {
         fn parse_helper(input: ParseStream, expr_style: bool) -> Result<Self> {
-            if input.peek(Token![super])
-                || input.peek(Token![self])
-                || input.peek(Token![crate])
-                || input.peek(Token![extern])
-            {
+            if input.peek(Token![super]) || input.peek(Token![self]) || input.peek(Token![crate]) {
                 let ident = input.call(Ident::parse_any)?;
                 return Ok(PathSegment::from(ident));
             }
 
             let ident = if input.peek(Token![Self]) {
                 input.call(Ident::parse_any)?
             } else {
                 input.parse()?
@@ -353,17 +349,17 @@ pub mod parsing {
                 },
             })
         }
     }
 
     impl Path {
         /// Parse a `Path` containing no path arguments on any of its segments.
         ///
-        /// *This function is available if Syn is built with the `"parsing"`
+        /// *This function is available only if Syn is built with the `"parsing"`
         /// feature.*
         ///
         /// # Example
         ///
         /// ```
         /// use syn::{Path, Result, Token};
         /// use syn::parse::{Parse, ParseStream};
         ///
@@ -395,17 +391,16 @@ pub mod parsing {
                 segments: {
                     let mut segments = Punctuated::new();
                     loop {
                         if !input.peek(Ident)
                             && !input.peek(Token![super])
                             && !input.peek(Token![self])
                             && !input.peek(Token![Self])
                             && !input.peek(Token![crate])
-                            && !input.peek(Token![extern])
                         {
                             break;
                         }
                         let ident = Ident::parse_any(input)?;
                         segments.push_value(PathSegment::from(ident));
                         if !input.peek(Token![::]) {
                             break;
                         }
@@ -428,17 +423,17 @@ pub mod parsing {
         /// For them to compare equal, it must be the case that:
         ///
         /// - the path has no leading colon,
         /// - the number of path segments is 1,
         /// - the first path segment has no angle bracketed or parenthesized
         ///   path arguments, and
         /// - the ident of the first path segment is equal to the given one.
         ///
-        /// *This function is available if Syn is built with the `"parsing"`
+        /// *This function is available only if Syn is built with the `"parsing"`
         /// feature.*
         ///
         /// # Example
         ///
         /// ```
         /// use syn::{Attribute, Error, Meta, NestedMeta, Result};
         /// # use std::iter::FromIterator;
         ///
@@ -467,17 +462,17 @@ pub mod parsing {
         ///
         /// A path is considered an ident if:
         ///
         /// - the path has no leading colon,
         /// - the number of path segments is 1, and
         /// - the first path segment has no angle bracketed or parenthesized
         ///   path arguments.
         ///
-        /// *This function is available if Syn is built with the `"parsing"`
+        /// *This function is available only if Syn is built with the `"parsing"`
         /// feature.*
         pub fn get_ident(&self) -> Option<&Ident> {
             if self.leading_colon.is_none()
                 && self.segments.len() == 1
                 && self.segments[0].arguments.is_none()
             {
                 Some(&self.segments[0].ident)
             } else {
diff --git a/third_party/rust/syn/src/punctuated.rs b/third_party/rust/syn/src/punctuated.rs
--- a/third_party/rust/syn/src/punctuated.rs
+++ b/third_party/rust/syn/src/punctuated.rs
@@ -17,16 +17,18 @@
 //!
 //! ```text
 //! a_function_call(arg1, arg2, arg3);
 //!                 ~~~~^ ~~~~^ ~~~~
 //! ```
 
 #[cfg(feature = "extra-traits")]
 use std::fmt::{self, Debug};
+#[cfg(feature = "extra-traits")]
+use std::hash::{Hash, Hasher};
 #[cfg(any(feature = "full", feature = "derive"))]
 use std::iter;
 use std::iter::FromIterator;
 use std::ops::{Index, IndexMut};
 use std::option;
 use std::slice;
 use std::vec;
 
@@ -36,18 +38,16 @@ use crate::parse::{Parse, ParseStream, R
 use crate::token::Token;
 
 /// A punctuated sequence of syntax tree nodes of type `T` separated by
 /// punctuation of type `P`.
 ///
 /// Refer to the [module documentation] for details about punctuated sequences.
 ///
 /// [module documentation]: self
-#[cfg_attr(feature = "extra-traits", derive(Eq, PartialEq, Hash))]
-#[cfg_attr(feature = "clone-impls", derive(Clone))]
 pub struct Punctuated<T, P> {
     inner: Vec<(T, P)>,
     last: Option<Box<T>>,
 }
 
 impl<T, P> Punctuated<T, P> {
     /// Creates an empty punctuated sequence.
     pub fn new() -> Punctuated<T, P> {
@@ -71,32 +71,29 @@ impl<T, P> Punctuated<T, P> {
         self.inner.len() + if self.last.is_some() { 1 } else { 0 }
     }
 
     /// Borrows the first element in this sequence.
     pub fn first(&self) -> Option<&T> {
         self.iter().next()
     }
 
+    /// Mutably borrows the first element in this sequence.
+    pub fn first_mut(&mut self) -> Option<&mut T> {
+        self.iter_mut().next()
+    }
+
     /// Borrows the last element in this sequence.
     pub fn last(&self) -> Option<&T> {
-        if self.last.is_some() {
-            self.last.as_ref().map(Box::as_ref)
-        } else {
-            self.inner.last().map(|pair| &pair.0)
-        }
+        self.iter().next_back()
     }
 
     /// Mutably borrows the last element in this sequence.
     pub fn last_mut(&mut self) -> Option<&mut T> {
-        if self.last.is_some() {
-            self.last.as_mut().map(Box::as_mut)
-        } else {
-            self.inner.last_mut().map(|pair| &mut pair.0)
-        }
+        self.iter_mut().next_back()
     }
 
     /// Returns an iterator over borrowed syntax tree nodes of type `&T`.
     pub fn iter(&self) -> Iter<T> {
         Iter {
             inner: Box::new(PrivateIter {
                 inner: self.inner.iter(),
                 last: self.last.as_ref().map(Box::as_ref).into_iter(),
@@ -225,23 +222,29 @@ impl<T, P> Punctuated<T, P> {
 
         if index == self.len() {
             self.push(value);
         } else {
             self.inner.insert(index, (value, Default::default()));
         }
     }
 
+    /// Clears the sequence of all values and punctuation, making it empty.
+    pub fn clear(&mut self) {
+        self.inner.clear();
+        self.last = None;
+    }
+
     /// Parses zero or more occurrences of `T` separated by punctuation of type
     /// `P`, with optional trailing punctuation.
     ///
     /// Parsing continues until the end of this parse stream. The entire content
     /// of this parse stream must consist of `T` and `P`.
     ///
-    /// *This function is available if Syn is built with the `"parsing"`
+    /// *This function is available only if Syn is built with the `"parsing"`
     /// feature.*
     #[cfg(feature = "parsing")]
     pub fn parse_terminated(input: ParseStream) -> Result<Self>
     where
         T: Parse,
         P: Parse,
     {
         Self::parse_terminated_with(input, T::parse)
@@ -251,17 +254,17 @@ impl<T, P> Punctuated<T, P> {
     /// separated by punctuation of type `P`, with optional trailing
     /// punctuation.
     ///
     /// Like [`parse_terminated`], the entire content of this stream is expected
     /// to be parsed.
     ///
     /// [`parse_terminated`]: Punctuated::parse_terminated
     ///
-    /// *This function is available if Syn is built with the `"parsing"`
+    /// *This function is available only if Syn is built with the `"parsing"`
     /// feature.*
     #[cfg(feature = "parsing")]
     pub fn parse_terminated_with(
         input: ParseStream,
         parser: fn(ParseStream) -> Result<T>,
     ) -> Result<Self>
     where
         P: Parse,
@@ -287,17 +290,17 @@ impl<T, P> Punctuated<T, P> {
     /// Parses one or more occurrences of `T` separated by punctuation of type
     /// `P`, not accepting trailing punctuation.
     ///
     /// Parsing continues as long as punctuation `P` is present at the head of
     /// the stream. This method returns upon parsing a `T` and observing that it
     /// is not followed by a `P`, even if there are remaining tokens in the
     /// stream.
     ///
-    /// *This function is available if Syn is built with the `"parsing"`
+    /// *This function is available only if Syn is built with the `"parsing"`
     /// feature.*
     #[cfg(feature = "parsing")]
     pub fn parse_separated_nonempty(input: ParseStream) -> Result<Self>
     where
         T: Parse,
         P: Token + Parse,
     {
         Self::parse_separated_nonempty_with(input, T::parse)
@@ -307,17 +310,17 @@ impl<T, P> Punctuated<T, P> {
     /// separated by punctuation of type `P`, not accepting trailing
     /// punctuation.
     ///
     /// Like [`parse_separated_nonempty`], may complete early without parsing
     /// the entire content of this stream.
     ///
     /// [`parse_separated_nonempty`]: Punctuated::parse_separated_nonempty
     ///
-    /// *This function is available if Syn is built with the `"parsing"`
+    /// *This function is available only if Syn is built with the `"parsing"`
     /// feature.*
     #[cfg(feature = "parsing")]
     pub fn parse_separated_nonempty_with(
         input: ParseStream,
         parser: fn(ParseStream) -> Result<T>,
     ) -> Result<Self>
     where
         P: Token + Parse,
@@ -333,16 +336,63 @@ impl<T, P> Punctuated<T, P> {
             let punct = input.parse()?;
             punctuated.push_punct(punct);
         }
 
         Ok(punctuated)
     }
 }
 
+#[cfg(feature = "clone-impls")]
+impl<T, P> Clone for Punctuated<T, P>
+where
+    T: Clone,
+    P: Clone,
+{
+    fn clone(&self) -> Self {
+        Punctuated {
+            inner: self.inner.clone(),
+            last: self.last.clone(),
+        }
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+impl<T, P> Eq for Punctuated<T, P>
+where
+    T: Eq,
+    P: Eq,
+{
+}
+
+#[cfg(feature = "extra-traits")]
+impl<T, P> PartialEq for Punctuated<T, P>
+where
+    T: PartialEq,
+    P: PartialEq,
+{
+    fn eq(&self, other: &Self) -> bool {
+        let Punctuated { inner, last } = self;
+        *inner == other.inner && *last == other.last
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+impl<T, P> Hash for Punctuated<T, P>
+where
+    T: Hash,
+    P: Hash,
+{
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        let Punctuated { inner, last } = self;
+        inner.hash(state);
+        last.hash(state);
+    }
+}
+
 #[cfg(feature = "extra-traits")]
 impl<T: Debug, P: Debug> Debug for Punctuated<T, P> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let mut list = f.debug_list();
         for (t, p) in &self.inner {
             list.entry(t);
             list.entry(p);
         }
@@ -531,17 +581,16 @@ impl<'a, T, P> ExactSizeIterator for Pai
     }
 }
 
 /// An iterator over owned pairs of type `Pair<T, P>`.
 ///
 /// Refer to the [module documentation] for details about punctuated sequences.
 ///
 /// [module documentation]: self
-#[derive(Clone)]
 pub struct IntoPairs<T, P> {
     inner: vec::IntoIter<(T, P)>,
     last: option::IntoIter<T>,
 }
 
 impl<T, P> Iterator for IntoPairs<T, P> {
     type Item = Pair<T, P>;
 
@@ -567,22 +616,34 @@ impl<T, P> DoubleEndedIterator for IntoP
 }
 
 impl<T, P> ExactSizeIterator for IntoPairs<T, P> {
     fn len(&self) -> usize {
         self.inner.len() + self.last.len()
     }
 }
 
+impl<T, P> Clone for IntoPairs<T, P>
+where
+    T: Clone,
+    P: Clone,
+{
+    fn clone(&self) -> Self {
+        IntoPairs {
+            inner: self.inner.clone(),
+            last: self.last.clone(),
+        }
+    }
+}
+
 /// An iterator over owned values of type `T`.
 ///
 /// Refer to the [module documentation] for details about punctuated sequences.
 ///
 /// [module documentation]: self
-#[derive(Clone)]
 pub struct IntoIter<T> {
     inner: vec::IntoIter<T>,
 }
 
 impl<T> Iterator for IntoIter<T> {
     type Item = T;
 
     fn next(&mut self) -> Option<Self::Item> {
@@ -601,16 +662,27 @@ impl<T> DoubleEndedIterator for IntoIter
 }
 
 impl<T> ExactSizeIterator for IntoIter<T> {
     fn len(&self) -> usize {
         self.inner.len()
     }
 }
 
+impl<T> Clone for IntoIter<T>
+where
+    T: Clone,
+{
+    fn clone(&self) -> Self {
+        IntoIter {
+            inner: self.inner.clone(),
+        }
+    }
+}
+
 /// An iterator over borrowed values of type `&T`.
 ///
 /// Refer to the [module documentation] for details about punctuated sequences.
 ///
 /// [module documentation]: self
 pub struct Iter<'a, T: 'a> {
     // The `Item = &'a T` needs to be specified to support rustc 1.31 and older.
     // On modern compilers we would be able to write just IterTrait<'a, T> where
@@ -794,17 +866,16 @@ impl<'a, T: 'a, I: 'a> IterMutTrait<'a, 
 }
 
 /// A single syntax tree node of type `T` followed by its trailing punctuation
 /// of type `P` if any.
 ///
 /// Refer to the [module documentation] for details about punctuated sequences.
 ///
 /// [module documentation]: self
-#[cfg_attr(feature = "clone-impls", derive(Clone))]
 pub enum Pair<T, P> {
     Punctuated(T, P),
     End(T),
 }
 
 impl<T, P> Pair<T, P> {
     /// Extracts the syntax tree node from this punctuated pair, discarding the
     /// following punctuation.
@@ -851,16 +922,30 @@ impl<T, P> Pair<T, P> {
     pub fn into_tuple(self) -> (T, Option<P>) {
         match self {
             Pair::Punctuated(t, d) => (t, Some(d)),
             Pair::End(t) => (t, None),
         }
     }
 }
 
+#[cfg(feature = "clone-impls")]
+impl<T, P> Clone for Pair<T, P>
+where
+    T: Clone,
+    P: Clone,
+{
+    fn clone(&self) -> Self {
+        match self {
+            Pair::Punctuated(t, p) => Pair::Punctuated(t.clone(), p.clone()),
+            Pair::End(t) => Pair::End(t.clone()),
+        }
+    }
+}
+
 impl<T, P> Index<usize> for Punctuated<T, P> {
     type Output = T;
 
     fn index(&self, index: usize) -> &Self::Output {
         if index == self.len() - 1 {
             match &self.last {
                 Some(t) => t,
                 None => &self.inner[index].0,
diff --git a/third_party/rust/syn/src/reserved.rs b/third_party/rust/syn/src/reserved.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/src/reserved.rs
@@ -0,0 +1,42 @@
+// Type for a syntax tree node that is reserved for future use.
+//
+// For example ExprReference contains a field `raw` of type Reserved. If `&raw
+// place` syntax becomes a thing as per https://github.com/rust-lang/rfcs/pull/2582,
+// we can backward compatibly change `raw`'s type to Option<Token![raw]> without
+// the possibility of breaking any code.
+
+use proc_macro2::Span;
+use std::marker::PhantomData;
+
+#[cfg(feature = "extra-traits")]
+use std::fmt::{self, Debug};
+
+ast_struct! {
+    pub struct Reserved {
+        _private: PhantomData<Span>,
+    }
+}
+
+impl Default for Reserved {
+    fn default() -> Self {
+        Reserved {
+            _private: PhantomData,
+        }
+    }
+}
+
+#[cfg(feature = "clone-impls")]
+impl Clone for Reserved {
+    fn clone(&self) -> Self {
+        Reserved {
+            _private: self._private,
+        }
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+impl Debug for Reserved {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.debug_struct("Reserved").finish()
+    }
+}
diff --git a/third_party/rust/syn/src/spanned.rs b/third_party/rust/syn/src/spanned.rs
--- a/third_party/rust/syn/src/spanned.rs
+++ b/third_party/rust/syn/src/spanned.rs
@@ -1,12 +1,12 @@
 //! A trait that can provide the `Span` of the complete contents of a syntax
 //! tree node.
 //!
-//! *This module is available if Syn is built with both the `"parsing"` and
+//! *This module is available only if Syn is built with both the `"parsing"` and
 //! `"printing"` features.*
 //!
 //! <br>
 //!
 //! # Example
 //!
 //! Suppose in a procedural macro we have a [`Type`] that we want to assert
 //! implements the [`Sync`] trait. Maybe this is the type of one of the fields
@@ -92,17 +92,17 @@ use quote::spanned::Spanned as ToTokens;
 /// [`ToTokens`] from the `quote` crate, as well as for `Span` itself.
 ///
 /// [`ToTokens`]: quote::ToTokens
 ///
 /// See the [module documentation] for an example.
 ///
 /// [module documentation]: self
 ///
-/// *This trait is available if Syn is built with both the `"parsing"` and
+/// *This trait is available only if Syn is built with both the `"parsing"` and
 /// `"printing"` features.*
 pub trait Spanned {
     /// Returns a `Span` covering the complete contents of this syntax tree
     /// node, or [`Span::call_site()`] if this node is empty.
     ///
     /// [`Span::call_site()`]: proc_macro2::Span::call_site
     fn span(&self) -> Span;
 }
diff --git a/third_party/rust/syn/src/stmt.rs b/third_party/rust/syn/src/stmt.rs
--- a/third_party/rust/syn/src/stmt.rs
+++ b/third_party/rust/syn/src/stmt.rs
@@ -1,25 +1,25 @@
 use super::*;
 
 ast_struct! {
     /// A braced block containing Rust statements.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct Block {
         pub brace_token: token::Brace,
         /// Statements in a block
         pub stmts: Vec<Stmt>,
     }
 }
 
 ast_enum! {
     /// A statement, usually ending in a semicolon.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub enum Stmt {
         /// A local (let) binding.
         Local(Local),
 
         /// An item definition.
         Item(Item),
 
         /// Expr without trailing semicolon.
@@ -28,38 +28,39 @@ ast_enum! {
         /// Expression with trailing semicolon.
         Semi(Expr, Token![;]),
     }
 }
 
 ast_struct! {
     /// A local `let` binding: `let x: u64 = s.parse()?`.
     ///
-    /// *This type is available if Syn is built with the `"full"` feature.*
+    /// *This type is available only if Syn is built with the `"full"` feature.*
     pub struct Local {
         pub attrs: Vec<Attribute>,
         pub let_token: Token![let],
         pub pat: Pat,
         pub init: Option<(Token![=], Box<Expr>)>,
         pub semi_token: Token![;],
     }
 }
 
 #[cfg(feature = "parsing")]
 pub mod parsing {
     use super::*;
 
+    use crate::parse::discouraged::Speculative;
     use crate::parse::{Parse, ParseStream, Result};
-    use crate::punctuated::Punctuated;
+    use proc_macro2::TokenStream;
 
     impl Block {
         /// Parse the body of a block as zero or more statements, possibly
         /// including one trailing expression.
         ///
-        /// *This function is available if Syn is built with the `"parsing"`
+        /// *This function is available only if Syn is built with the `"parsing"`
         /// feature.*
         ///
         /// # Example
         ///
         /// ```
         /// use syn::{braced, token, Attribute, Block, Ident, Result, Stmt, Token};
         /// use syn::parse::{Parse, ParseStream};
         ///
@@ -101,18 +102,18 @@ pub mod parsing {
         ///             stmts,
         ///         })
         ///     }
         /// }
         /// ```
         pub fn parse_within(input: ParseStream) -> Result<Vec<Stmt>> {
             let mut stmts = Vec::new();
             loop {
-                while input.peek(Token![;]) {
-                    input.parse::<Token![;]>()?;
+                while let Some(semi) = input.parse::<Option<Token![;]>>()? {
+                    stmts.push(Stmt::Semi(Expr::Verbatim(TokenStream::new()), semi));
                 }
                 if input.is_empty() {
                     break;
                 }
                 let s = parse_stmt(input, true)?;
                 let requires_semicolon = if let Stmt::Expr(s) = &s {
                     expr::requires_terminator(s)
                 } else {
@@ -141,65 +142,65 @@ pub mod parsing {
 
     impl Parse for Stmt {
         fn parse(input: ParseStream) -> Result<Self> {
             parse_stmt(input, false)
         }
     }
 
     fn parse_stmt(input: ParseStream, allow_nosemi: bool) -> Result<Stmt> {
-        // TODO: optimize using advance_to
+        let mut attrs = input.call(Attribute::parse_outer)?;
+
+        // brace-style macros; paren and bracket macros get parsed as
+        // expression statements.
         let ahead = input.fork();
-        ahead.call(Attribute::parse_outer)?;
+        if let Ok(path) = ahead.call(Path::parse_mod_style) {
+            if ahead.peek(Token![!]) && (ahead.peek2(token::Brace) || ahead.peek2(Ident)) {
+                input.advance_to(&ahead);
+                return stmt_mac(input, attrs, path);
+            }
+        }
 
-        if {
-            let ahead = ahead.fork();
-            // Only parse braces here; paren and bracket will get parsed as
-            // expression statements
-            ahead.call(Path::parse_mod_style).is_ok()
-                && ahead.parse::<Token![!]>().is_ok()
-                && (ahead.peek(token::Brace) || ahead.peek(Ident))
-        } {
-            stmt_mac(input)
-        } else if ahead.peek(Token![let]) {
-            stmt_local(input).map(Stmt::Local)
-        } else if ahead.peek(Token![pub])
-            || ahead.peek(Token![crate]) && !ahead.peek2(Token![::])
-            || ahead.peek(Token![extern]) && !ahead.peek2(Token![::])
-            || ahead.peek(Token![use])
-            || ahead.peek(Token![static]) && (ahead.peek2(Token![mut]) || ahead.peek2(Ident))
-            || ahead.peek(Token![const])
-            || ahead.peek(Token![unsafe]) && !ahead.peek2(token::Brace)
-            || ahead.peek(Token![async])
-                && (ahead.peek2(Token![unsafe])
-                    || ahead.peek2(Token![extern])
-                    || ahead.peek2(Token![fn]))
-            || ahead.peek(Token![fn])
-            || ahead.peek(Token![mod])
-            || ahead.peek(Token![type])
-            || ahead.peek(item::parsing::existential) && ahead.peek2(Token![type])
-            || ahead.peek(Token![struct])
-            || ahead.peek(Token![enum])
-            || ahead.peek(Token![union]) && ahead.peek2(Ident)
-            || ahead.peek(Token![auto]) && ahead.peek2(Token![trait])
-            || ahead.peek(Token![trait])
-            || ahead.peek(Token![default])
-                && (ahead.peek2(Token![unsafe]) || ahead.peek2(Token![impl]))
-            || ahead.peek(Token![impl])
-            || ahead.peek(Token![macro])
+        if input.peek(Token![let]) {
+            stmt_local(input, attrs).map(Stmt::Local)
+        } else if input.peek(Token![pub])
+            || input.peek(Token![crate]) && !input.peek2(Token![::])
+            || input.peek(Token![extern])
+            || input.peek(Token![use])
+            || input.peek(Token![static]) && (input.peek2(Token![mut]) || input.peek2(Ident))
+            || input.peek(Token![const])
+            || input.peek(Token![unsafe]) && !input.peek2(token::Brace)
+            || input.peek(Token![async])
+                && (input.peek2(Token![unsafe])
+                    || input.peek2(Token![extern])
+                    || input.peek2(Token![fn]))
+            || input.peek(Token![fn])
+            || input.peek(Token![mod])
+            || input.peek(Token![type])
+            || input.peek(item::parsing::existential) && input.peek2(Token![type])
+            || input.peek(Token![struct])
+            || input.peek(Token![enum])
+            || input.peek(Token![union]) && input.peek2(Ident)
+            || input.peek(Token![auto]) && input.peek2(Token![trait])
+            || input.peek(Token![trait])
+            || input.peek(Token![default])
+                && (input.peek2(Token![unsafe]) || input.peek2(Token![impl]))
+            || input.peek(Token![impl])
+            || input.peek(Token![macro])
         {
-            input.parse().map(Stmt::Item)
+            let mut item: Item = input.parse()?;
+            attrs.extend(item.replace_attrs(Vec::new()));
+            item.replace_attrs(attrs);
+            Ok(Stmt::Item(item))
         } else {
-            stmt_expr(input, allow_nosemi)
+            stmt_expr(input, allow_nosemi, attrs)
         }
     }
 
-    fn stmt_mac(input: ParseStream) -> Result<Stmt> {
-        let attrs = input.call(Attribute::parse_outer)?;
-        let path = input.call(Path::parse_mod_style)?;
+    fn stmt_mac(input: ParseStream, attrs: Vec<Attribute>, path: Path) -> Result<Stmt> {
         let bang_token: Token![!] = input.parse()?;
         let ident: Option<Ident> = input.parse()?;
         let (delimiter, tokens) = mac::parse_delimiter(input)?;
         let semi_token: Option<Token![;]> = input.parse()?;
 
         Ok(Stmt::Item(Item::Macro(ItemMacro {
             attrs,
             ident,
@@ -208,43 +209,22 @@ pub mod parsing {
                 bang_token,
                 delimiter,
                 tokens,
             },
             semi_token,
         })))
     }
 
-    fn stmt_local(input: ParseStream) -> Result<Local> {
+    fn stmt_local(input: ParseStream, attrs: Vec<Attribute>) -> Result<Local> {
         Ok(Local {
-            attrs: input.call(Attribute::parse_outer)?,
+            attrs,
             let_token: input.parse()?,
             pat: {
-                let leading_vert: Option<Token![|]> = input.parse()?;
-                let mut pat: Pat = input.parse()?;
-                if leading_vert.is_some()
-                    || input.peek(Token![|]) && !input.peek(Token![||]) && !input.peek(Token![|=])
-                {
-                    let mut cases = Punctuated::new();
-                    cases.push_value(pat);
-                    while input.peek(Token![|])
-                        && !input.peek(Token![||])
-                        && !input.peek(Token![|=])
-                    {
-                        let punct = input.parse()?;
-                        cases.push_punct(punct);
-                        let pat: Pat = input.parse()?;
-                        cases.push_value(pat);
-                    }
-                    pat = Pat::Or(PatOr {
-                        attrs: Vec::new(),
-                        leading_vert,
-                        cases,
-                    });
-                }
+                let mut pat: Pat = pat::parsing::multi_pat_with_leading_vert(input)?;
                 if input.peek(Token![:]) {
                     let colon_token: Token![:] = input.parse()?;
                     let ty: Type = input.parse()?;
                     pat = Pat::Type(PatType {
                         attrs: Vec::new(),
                         pat: Box::new(pat),
                         colon_token,
                         ty: Box::new(ty),
@@ -260,22 +240,29 @@ pub mod parsing {
                 } else {
                     None
                 }
             },
             semi_token: input.parse()?,
         })
     }
 
-    fn stmt_expr(input: ParseStream, allow_nosemi: bool) -> Result<Stmt> {
-        let mut attrs = input.call(Attribute::parse_outer)?;
+    fn stmt_expr(
+        input: ParseStream,
+        allow_nosemi: bool,
+        mut attrs: Vec<Attribute>,
+    ) -> Result<Stmt> {
         let mut e = expr::parsing::expr_early(input)?;
 
-        attrs.extend(e.replace_attrs(Vec::new()));
-        e.replace_attrs(attrs);
+        let mut attr_target = &mut e;
+        while let Expr::Binary(e) = attr_target {
+            attr_target = &mut e.left;
+        }
+        attrs.extend(attr_target.replace_attrs(Vec::new()));
+        attr_target.replace_attrs(attrs);
 
         if input.peek(Token![;]) {
             return Ok(Stmt::Semi(e, input.parse()?));
         }
 
         if allow_nosemi || !expr::requires_terminator(&e) {
             Ok(Stmt::Expr(e))
         } else {
diff --git a/third_party/rust/syn/src/token.rs b/third_party/rust/syn/src/token.rs
--- a/third_party/rust/syn/src/token.rs
+++ b/third_party/rust/syn/src/token.rs
@@ -83,44 +83,41 @@
 //!
 //! - Field access to its span — `let sp = the_token.span`
 //!
 //! [Peeking]: ../parse/struct.ParseBuffer.html#method.peek
 //! [Parsing]: ../parse/struct.ParseBuffer.html#method.parse
 //! [Printing]: https://docs.rs/quote/1.0/quote/trait.ToTokens.html
 //! [`Span`]: https://docs.rs/proc-macro2/1.0/proc_macro2/struct.Span.html
 
-use std;
 #[cfg(feature = "extra-traits")]
 use std::cmp;
 #[cfg(feature = "extra-traits")]
 use std::fmt::{self, Debug};
 #[cfg(feature = "extra-traits")]
 use std::hash::{Hash, Hasher};
 use std::ops::{Deref, DerefMut};
 
-#[cfg(feature = "parsing")]
-use proc_macro2::Delimiter;
 #[cfg(any(feature = "parsing", feature = "printing"))]
 use proc_macro2::Ident;
 use proc_macro2::Span;
 #[cfg(feature = "printing")]
 use proc_macro2::TokenStream;
+#[cfg(feature = "parsing")]
+use proc_macro2::{Delimiter, Literal, Punct, TokenTree};
 #[cfg(feature = "printing")]
 use quote::{ToTokens, TokenStreamExt};
 
 use self::private::WithSpan;
 #[cfg(feature = "parsing")]
 use crate::buffer::Cursor;
 #[cfg(feature = "parsing")]
 use crate::error::Result;
-#[cfg(any(feature = "full", feature = "derive"))]
 #[cfg(feature = "parsing")]
 use crate::lifetime::Lifetime;
-#[cfg(any(feature = "full", feature = "derive"))]
 #[cfg(feature = "parsing")]
 use crate::lit::{Lit, LitBool, LitByte, LitByteStr, LitChar, LitFloat, LitInt, LitStr};
 #[cfg(feature = "parsing")]
 use crate::lookahead;
 #[cfg(feature = "parsing")]
 use crate::parse::{Parse, ParseStream};
 use crate::span::IntoSpans;
 
@@ -150,31 +147,30 @@ mod private {
     pub struct WithSpan {
         pub span: Span,
     }
 }
 
 #[cfg(feature = "parsing")]
 impl private::Sealed for Ident {}
 
-#[cfg(any(feature = "full", feature = "derive"))]
 #[cfg(feature = "parsing")]
 fn peek_impl(cursor: Cursor, peek: fn(ParseStream) -> bool) -> bool {
+    use crate::parse::Unexpected;
     use std::cell::Cell;
     use std::rc::Rc;
 
     let scope = Span::call_site();
-    let unexpected = Rc::new(Cell::new(None));
+    let unexpected = Rc::new(Cell::new(Unexpected::None));
     let buffer = crate::parse::new_parse_buffer(scope, cursor, unexpected);
     peek(&buffer)
 }
 
-#[cfg(any(feature = "full", feature = "derive"))]
 macro_rules! impl_token {
-    ($name:ident $display:expr) => {
+    ($display:tt $name:ty) => {
         #[cfg(feature = "parsing")]
         impl Token for $name {
             fn peek(cursor: Cursor) -> bool {
                 fn peek(input: ParseStream) -> bool {
                     <$name as Parse>::parse(input).is_ok()
                 }
                 peek_impl(cursor, peek)
             }
@@ -184,34 +180,48 @@ macro_rules! impl_token {
             }
         }
 
         #[cfg(feature = "parsing")]
         impl private::Sealed for $name {}
     };
 }
 
-#[cfg(any(feature = "full", feature = "derive"))]
-impl_token!(Lifetime "lifetime");
-#[cfg(any(feature = "full", feature = "derive"))]
-impl_token!(Lit "literal");
-#[cfg(any(feature = "full", feature = "derive"))]
-impl_token!(LitStr "string literal");
-#[cfg(any(feature = "full", feature = "derive"))]
-impl_token!(LitByteStr "byte string literal");
-#[cfg(any(feature = "full", feature = "derive"))]
-impl_token!(LitByte "byte literal");
-#[cfg(any(feature = "full", feature = "derive"))]
-impl_token!(LitChar "character literal");
-#[cfg(any(feature = "full", feature = "derive"))]
-impl_token!(LitInt "integer literal");
-#[cfg(any(feature = "full", feature = "derive"))]
-impl_token!(LitFloat "floating point literal");
-#[cfg(any(feature = "full", feature = "derive"))]
-impl_token!(LitBool "boolean literal");
+impl_token!("lifetime" Lifetime);
+impl_token!("literal" Lit);
+impl_token!("string literal" LitStr);
+impl_token!("byte string literal" LitByteStr);
+impl_token!("byte literal" LitByte);
+impl_token!("character literal" LitChar);
+impl_token!("integer literal" LitInt);
+impl_token!("floating point literal" LitFloat);
+impl_token!("boolean literal" LitBool);
+impl_token!("group token" proc_macro2::Group);
+
+macro_rules! impl_low_level_token {
+    ($display:tt $ty:ident $get:ident) => {
+        #[cfg(feature = "parsing")]
+        impl Token for $ty {
+            fn peek(cursor: Cursor) -> bool {
+                cursor.$get().is_some()
+            }
+
+            fn display() -> &'static str {
+                $display
+            }
+        }
+
+        #[cfg(feature = "parsing")]
+        impl private::Sealed for $ty {}
+    };
+}
+
+impl_low_level_token!("punctuation token" Punct punct);
+impl_low_level_token!("literal" Literal literal);
+impl_low_level_token!("token" TokenTree token_tree);
 
 // Not public API.
 #[doc(hidden)]
 #[cfg(feature = "parsing")]
 pub trait CustomToken {
     fn peek(cursor: Cursor) -> bool;
     fn display() -> &'static str;
 }
@@ -228,17 +238,16 @@ impl<T: CustomToken> Token for T {
     fn display() -> &'static str {
         <Self as CustomToken>::display()
     }
 }
 
 macro_rules! define_keywords {
     ($($token:tt pub struct $name:ident #[$doc:meta])*) => {
         $(
-            #[cfg_attr(feature = "clone-impls", derive(Copy, Clone))]
             #[$doc]
             ///
             /// Don't try to remember the name of this type &mdash; use the
             /// [`Token!`] macro instead.
             ///
             /// [`Token!`]: crate::token
             pub struct $name {
                 pub span: Span,
@@ -255,16 +264,26 @@ macro_rules! define_keywords {
             impl std::default::Default for $name {
                 fn default() -> Self {
                     $name {
                         span: Span::call_site(),
                     }
                 }
             }
 
+            #[cfg(feature = "clone-impls")]
+            impl Copy for $name {}
+
+            #[cfg(feature = "clone-impls")]
+            impl Clone for $name {
+                fn clone(&self) -> Self {
+                    *self
+                }
+            }
+
             #[cfg(feature = "extra-traits")]
             impl Debug for $name {
                 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
                     f.write_str(stringify!($name))
                 }
             }
 
             #[cfg(feature = "extra-traits")]
@@ -333,17 +352,16 @@ macro_rules! impl_deref_if_len_is_1 {
     };
 
     ($name:ident/$len:tt) => {};
 }
 
 macro_rules! define_punctuation_structs {
     ($($token:tt pub struct $name:ident/$len:tt #[$doc:meta])*) => {
         $(
-            #[cfg_attr(feature = "clone-impls", derive(Copy, Clone))]
             #[repr(C)]
             #[$doc]
             ///
             /// Don't try to remember the name of this type &mdash; use the
             /// [`Token!`] macro instead.
             ///
             /// [`Token!`]: crate::token
             pub struct $name {
@@ -361,16 +379,26 @@ macro_rules! define_punctuation_structs 
             impl std::default::Default for $name {
                 fn default() -> Self {
                     $name {
                         spans: [Span::call_site(); $len],
                     }
                 }
             }
 
+            #[cfg(feature = "clone-impls")]
+            impl Copy for $name {}
+
+            #[cfg(feature = "clone-impls")]
+            impl Clone for $name {
+                fn clone(&self) -> Self {
+                    *self
+                }
+            }
+
             #[cfg(feature = "extra-traits")]
             impl Debug for $name {
                 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
                     f.write_str(stringify!($name))
                 }
             }
 
             #[cfg(feature = "extra-traits")]
@@ -431,17 +459,16 @@ macro_rules! define_punctuation {
             impl private::Sealed for $name {}
         )*
     };
 }
 
 macro_rules! define_delimiters {
     ($($token:tt pub struct $name:ident #[$doc:meta])*) => {
         $(
-            #[cfg_attr(feature = "clone-impls", derive(Copy, Clone))]
             #[$doc]
             pub struct $name {
                 pub span: Span,
             }
 
             #[doc(hidden)]
             #[allow(non_snake_case)]
             pub fn $name<S: IntoSpans<[Span; 1]>>(span: S) -> $name {
@@ -453,16 +480,26 @@ macro_rules! define_delimiters {
             impl std::default::Default for $name {
                 fn default() -> Self {
                     $name {
                         span: Span::call_site(),
                     }
                 }
             }
 
+            #[cfg(feature = "clone-impls")]
+            impl Copy for $name {}
+
+            #[cfg(feature = "clone-impls")]
+            impl Clone for $name {
+                fn clone(&self) -> Self {
+                    *self
+                }
+            }
+
             #[cfg(feature = "extra-traits")]
             impl Debug for $name {
                 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
                     f.write_str(stringify!($name))
                 }
             }
 
             #[cfg(feature = "extra-traits")]
@@ -850,17 +887,17 @@ pub mod parsing {
         if let Some((ident, _rest)) = cursor.ident() {
             ident == token
         } else {
             false
         }
     }
 
     pub fn punct<S: FromSpans>(input: ParseStream, token: &str) -> Result<S> {
-        let mut spans = [input.cursor().span(); 3];
+        let mut spans = [input.span(); 3];
         punct_helper(input, token, &mut spans)?;
         Ok(S::from_spans(&spans))
     }
 
     fn punct_helper(input: ParseStream, token: &str, spans: &mut [Span; 3]) -> Result<()> {
         input.step(|cursor| {
             let mut cursor = *cursor;
             assert!(token.len() <= spans.len());
diff --git a/third_party/rust/syn/src/tt.rs b/third_party/rust/syn/src/tt.rs
--- a/third_party/rust/syn/src/tt.rs
+++ b/third_party/rust/syn/src/tt.rs
@@ -13,18 +13,18 @@ impl<'a> PartialEq for TokenTreeHelper<'
                 match (g1.delimiter(), g2.delimiter()) {
                     (Delimiter::Parenthesis, Delimiter::Parenthesis)
                     | (Delimiter::Brace, Delimiter::Brace)
                     | (Delimiter::Bracket, Delimiter::Bracket)
                     | (Delimiter::None, Delimiter::None) => {}
                     _ => return false,
                 }
 
-                let s1 = g1.stream().clone().into_iter();
-                let mut s2 = g2.stream().clone().into_iter();
+                let s1 = g1.stream().into_iter();
+                let mut s2 = g2.stream().into_iter();
 
                 for item1 in s1 {
                     let item2 = match s2.next() {
                         Some(item) => item,
                         None => return false,
                     };
                     if TokenTreeHelper(&item1) != TokenTreeHelper(&item2) {
                         return false;
@@ -55,17 +55,17 @@ impl<'a> Hash for TokenTreeHelper<'a> {
                 0u8.hash(h);
                 match g.delimiter() {
                     Delimiter::Parenthesis => 0u8.hash(h),
                     Delimiter::Brace => 1u8.hash(h),
                     Delimiter::Bracket => 2u8.hash(h),
                     Delimiter::None => 3u8.hash(h),
                 }
 
-                for item in g.stream().clone() {
+                for item in g.stream() {
                     TokenTreeHelper(&item).hash(h);
                 }
                 0xffu8.hash(h); // terminator w/ a variant we don't normally hash
             }
             TokenTree::Punct(op) => {
                 1u8.hash(h);
                 op.as_char().hash(h);
                 match op.spacing() {
diff --git a/third_party/rust/syn/src/ty.rs b/third_party/rust/syn/src/ty.rs
--- a/third_party/rust/syn/src/ty.rs
+++ b/third_party/rust/syn/src/ty.rs
@@ -1,31 +1,27 @@
 use super::*;
 use crate::punctuated::Punctuated;
-#[cfg(feature = "extra-traits")]
-use crate::tt::TokenStreamHelper;
 use proc_macro2::TokenStream;
-#[cfg(feature = "extra-traits")]
-use std::hash::{Hash, Hasher};
 
 ast_enum_of_structs! {
     /// The possible types that a Rust value could have.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     ///
     /// # Syntax tree enum
     ///
     /// This type is a [syntax tree enum].
     ///
     /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums
     //
     // TODO: change syntax-tree-enum link to an intra rustdoc link, currently
     // blocked on https://github.com/rust-lang/rust/issues/62833
-    pub enum Type #manual_extra_traits {
+    pub enum Type {
         /// A fixed size array type: `[T; n]`.
         Array(TypeArray),
 
         /// A bare function type: `fn(usize) -> bool`.
         BareFn(TypeBareFn),
 
         /// A type contained within invisible delimiters.
         Group(TypeGroup),
@@ -72,295 +68,194 @@ ast_enum_of_structs! {
         #[doc(hidden)]
         __Nonexhaustive,
     }
 }
 
 ast_struct! {
     /// A fixed size array type: `[T; n]`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct TypeArray {
         pub bracket_token: token::Bracket,
         pub elem: Box<Type>,
         pub semi_token: Token![;],
         pub len: Expr,
     }
 }
 
 ast_struct! {
     /// A bare function type: `fn(usize) -> bool`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct TypeBareFn {
         pub lifetimes: Option<BoundLifetimes>,
         pub unsafety: Option<Token![unsafe]>,
         pub abi: Option<Abi>,
         pub fn_token: Token![fn],
         pub paren_token: token::Paren,
         pub inputs: Punctuated<BareFnArg, Token![,]>,
         pub variadic: Option<Variadic>,
         pub output: ReturnType,
     }
 }
 
 ast_struct! {
     /// A type contained within invisible delimiters.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct TypeGroup {
         pub group_token: token::Group,
         pub elem: Box<Type>,
     }
 }
 
 ast_struct! {
     /// An `impl Bound1 + Bound2 + Bound3` type where `Bound` is a trait or
     /// a lifetime.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct TypeImplTrait {
         pub impl_token: Token![impl],
         pub bounds: Punctuated<TypeParamBound, Token![+]>,
     }
 }
 
 ast_struct! {
     /// Indication that a type should be inferred by the compiler: `_`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct TypeInfer {
         pub underscore_token: Token![_],
     }
 }
 
 ast_struct! {
     /// A macro in the type position.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct TypeMacro {
         pub mac: Macro,
     }
 }
 
 ast_struct! {
     /// The never type: `!`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct TypeNever {
         pub bang_token: Token![!],
     }
 }
 
 ast_struct! {
     /// A parenthesized type equivalent to the inner type.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct TypeParen {
         pub paren_token: token::Paren,
         pub elem: Box<Type>,
     }
 }
 
 ast_struct! {
     /// A path like `std::slice::Iter`, optionally qualified with a
     /// self-type as in `<Vec<T> as SomeTrait>::Associated`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct TypePath {
         pub qself: Option<QSelf>,
         pub path: Path,
     }
 }
 
 ast_struct! {
     /// A raw pointer type: `*const T` or `*mut T`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct TypePtr {
         pub star_token: Token![*],
         pub const_token: Option<Token![const]>,
         pub mutability: Option<Token![mut]>,
         pub elem: Box<Type>,
     }
 }
 
 ast_struct! {
     /// A reference type: `&'a T` or `&'a mut T`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct TypeReference {
         pub and_token: Token![&],
         pub lifetime: Option<Lifetime>,
         pub mutability: Option<Token![mut]>,
         pub elem: Box<Type>,
     }
 }
 
 ast_struct! {
     /// A dynamically sized slice type: `[T]`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct TypeSlice {
         pub bracket_token: token::Bracket,
         pub elem: Box<Type>,
     }
 }
 
 ast_struct! {
     /// A trait object type `Bound1 + Bound2 + Bound3` where `Bound` is a
     /// trait or a lifetime.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct TypeTraitObject {
         pub dyn_token: Option<Token![dyn]>,
         pub bounds: Punctuated<TypeParamBound, Token![+]>,
     }
 }
 
 ast_struct! {
     /// A tuple type: `(A, B, C, String)`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or
+    /// *This type is available only if Syn is built with the `"derive"` or
     /// `"full"` feature.*
     pub struct TypeTuple {
         pub paren_token: token::Paren,
         pub elems: Punctuated<Type, Token![,]>,
     }
 }
 
-#[cfg(feature = "extra-traits")]
-impl Eq for Type {}
-
-#[cfg(feature = "extra-traits")]
-impl PartialEq for Type {
-    fn eq(&self, other: &Self) -> bool {
-        match (self, other) {
-            (Type::Array(this), Type::Array(other)) => this == other,
-            (Type::BareFn(this), Type::BareFn(other)) => this == other,
-            (Type::Group(this), Type::Group(other)) => this == other,
-            (Type::ImplTrait(this), Type::ImplTrait(other)) => this == other,
-            (Type::Infer(this), Type::Infer(other)) => this == other,
-            (Type::Macro(this), Type::Macro(other)) => this == other,
-            (Type::Never(this), Type::Never(other)) => this == other,
-            (Type::Paren(this), Type::Paren(other)) => this == other,
-            (Type::Path(this), Type::Path(other)) => this == other,
-            (Type::Ptr(this), Type::Ptr(other)) => this == other,
-            (Type::Reference(this), Type::Reference(other)) => this == other,
-            (Type::Slice(this), Type::Slice(other)) => this == other,
-            (Type::TraitObject(this), Type::TraitObject(other)) => this == other,
-            (Type::Tuple(this), Type::Tuple(other)) => this == other,
-            (Type::Verbatim(this), Type::Verbatim(other)) => {
-                TokenStreamHelper(this) == TokenStreamHelper(other)
-            }
-            _ => false,
-        }
-    }
-}
-
-#[cfg(feature = "extra-traits")]
-impl Hash for Type {
-    fn hash<H>(&self, hash: &mut H)
-    where
-        H: Hasher,
-    {
-        match self {
-            Type::Array(ty) => {
-                hash.write_u8(0);
-                ty.hash(hash);
-            }
-            Type::BareFn(ty) => {
-                hash.write_u8(1);
-                ty.hash(hash);
-            }
-            Type::Group(ty) => {
-                hash.write_u8(2);
-                ty.hash(hash);
-            }
-            Type::ImplTrait(ty) => {
-                hash.write_u8(3);
-                ty.hash(hash);
-            }
-            Type::Infer(ty) => {
-                hash.write_u8(4);
-                ty.hash(hash);
-            }
-            Type::Macro(ty) => {
-                hash.write_u8(5);
-                ty.hash(hash);
-            }
-            Type::Never(ty) => {
-                hash.write_u8(6);
-                ty.hash(hash);
-            }
-            Type::Paren(ty) => {
-                hash.write_u8(7);
-                ty.hash(hash);
-            }
-            Type::Path(ty) => {
-                hash.write_u8(8);
-                ty.hash(hash);
-            }
-            Type::Ptr(ty) => {
-                hash.write_u8(9);
-                ty.hash(hash);
-            }
-            Type::Reference(ty) => {
-                hash.write_u8(10);
-                ty.hash(hash);
-            }
-            Type::Slice(ty) => {
-                hash.write_u8(11);
-                ty.hash(hash);
-            }
-            Type::TraitObject(ty) => {
-                hash.write_u8(12);
-                ty.hash(hash);
-            }
-            Type::Tuple(ty) => {
-                hash.write_u8(13);
-                ty.hash(hash);
-            }
-            Type::Verbatim(ty) => {
-                hash.write_u8(14);
-                TokenStreamHelper(ty).hash(hash);
-            }
-            Type::__Nonexhaustive => unreachable!(),
-        }
-    }
-}
-
 ast_struct! {
     /// The binary interface of a function: `extern "C"`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub struct Abi {
         pub extern_token: Token![extern],
         pub name: Option<LitStr>,
     }
 }
 
 ast_struct! {
     /// An argument in a function type: the `usize` in `fn(usize) -> bool`.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub struct BareFnArg {
         pub attrs: Vec<Attribute>,
         pub name: Option<(Ident, Token![:])>,
         pub ty: Type,
     }
 }
 
@@ -372,28 +267,28 @@ ast_struct! {
     /// # struct c_int;
     /// #
     /// extern "C" {
     ///     fn printf(format: *const c_char, ...) -> c_int;
     ///     //                               ^^^
     /// }
     /// ```
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub struct Variadic {
         pub attrs: Vec<Attribute>,
         pub dots: Token![...],
     }
 }
 
 ast_enum! {
     /// Return type of a function signature.
     ///
-    /// *This type is available if Syn is built with the `"derive"` or `"full"`
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
     /// feature.*
     pub enum ReturnType {
         /// Return type is not specified.
         ///
         /// Functions default to `()` and closures default to type inference.
         Default,
         /// A particular type is returned.
         Type(Token![->], Box<Type>),
@@ -402,39 +297,44 @@ ast_enum! {
 
 #[cfg(feature = "parsing")]
 pub mod parsing {
     use super::*;
 
     use crate::ext::IdentExt;
     use crate::parse::{Parse, ParseStream, Result};
     use crate::path;
+    use proc_macro2::{Punct, Spacing, TokenTree};
+    use std::iter::FromIterator;
 
     impl Parse for Type {
         fn parse(input: ParseStream) -> Result<Self> {
-            ambig_ty(input, true)
+            let allow_plus = true;
+            ambig_ty(input, allow_plus)
         }
     }
 
     impl Type {
         /// In some positions, types may not contain the `+` character, to
         /// disambiguate them. For example in the expression `1 as T`, T may not
         /// contain a `+` character.
         ///
         /// This parser does not allow a `+`, while the default parser does.
         pub fn without_plus(input: ParseStream) -> Result<Self> {
-            ambig_ty(input, false)
+            let allow_plus = false;
+            ambig_ty(input, allow_plus)
         }
     }
 
     fn ambig_ty(input: ParseStream, allow_plus: bool) -> Result<Type> {
-        if input.peek(token::Group) {
+        if input.peek(token::Group) && !input.peek2(Token![::]) && !input.peek2(Token![<]) {
             return input.parse().map(Type::Group);
         }
 
+        let begin = input.fork();
         let mut lifetimes = None::<BoundLifetimes>;
         let mut lookahead = input.lookahead1();
         if lookahead.peek(Token![for]) {
             lifetimes = input.parse()?;
             lookahead = input.lookahead1();
             if !lookahead.peek(Ident)
                 && !lookahead.peek(Token![fn])
                 && !lookahead.peek(Token![unsafe])
@@ -519,17 +419,17 @@ pub mod parsing {
                             }
                             match bounds.into_iter().next().unwrap() {
                                 TypeParamBound::Trait(trait_bound) => {
                                     TypeParamBound::Trait(TraitBound {
                                         paren_token: Some(paren_token),
                                         ..trait_bound
                                     })
                                 }
-                                other => other,
+                                other @ TypeParamBound::Lifetime(_) => other,
                             }
                         }
                         _ => break,
                     };
                     return Ok(Type::TraitObject(TypeTraitObject {
                         dyn_token: None,
                         bounds: {
                             let mut bounds = Punctuated::new();
@@ -544,27 +444,30 @@ pub mod parsing {
                 }
             }
             Ok(Type::Paren(TypeParen {
                 paren_token,
                 elem: Box::new(first),
             }))
         } else if lookahead.peek(Token![fn])
             || lookahead.peek(Token![unsafe])
-            || lookahead.peek(Token![extern]) && !input.peek2(Token![::])
+            || lookahead.peek(Token![extern])
         {
-            let mut bare_fn: TypeBareFn = input.parse()?;
-            bare_fn.lifetimes = lifetimes;
-            Ok(Type::BareFn(bare_fn))
+            let allow_mut_self = true;
+            if let Some(mut bare_fn) = parse_bare_fn(input, allow_mut_self)? {
+                bare_fn.lifetimes = lifetimes;
+                Ok(Type::BareFn(bare_fn))
+            } else {
+                Ok(Type::Verbatim(verbatim::between(begin, input)))
+            }
         } else if lookahead.peek(Ident)
             || input.peek(Token![super])
             || input.peek(Token![self])
             || input.peek(Token![Self])
             || input.peek(Token![crate])
-            || input.peek(Token![extern])
             || lookahead.peek(Token![::])
             || lookahead.peek(Token![<])
         {
             if input.peek(Token![dyn]) {
                 let mut trait_object: TypeTraitObject = input.parse()?;
                 if lifetimes.is_some() {
                     match trait_object.bounds.iter_mut().next().unwrap() {
                         TypeParamBound::Trait(trait_bound) => {
@@ -717,48 +620,68 @@ pub mod parsing {
                 // & binds tighter than +, so we don't allow + here.
                 elem: Box::new(input.call(Type::without_plus)?),
             })
         }
     }
 
     impl Parse for TypeBareFn {
         fn parse(input: ParseStream) -> Result<Self> {
-            let args;
-            let allow_variadic;
-            Ok(TypeBareFn {
-                lifetimes: input.parse()?,
-                unsafety: input.parse()?,
-                abi: input.parse()?,
-                fn_token: input.parse()?,
-                paren_token: parenthesized!(args in input),
-                inputs: {
-                    let mut inputs = Punctuated::new();
-                    while !args.is_empty() && !args.peek(Token![...]) {
-                        inputs.push_value(args.parse()?);
-                        if args.is_empty() {
-                            break;
-                        }
-                        inputs.push_punct(args.parse()?);
+            let allow_mut_self = false;
+            parse_bare_fn(input, allow_mut_self).map(Option::unwrap)
+        }
+    }
+
+    fn parse_bare_fn(input: ParseStream, allow_mut_self: bool) -> Result<Option<TypeBareFn>> {
+        let args;
+        let mut variadic = None;
+        let mut has_mut_self = false;
+
+        let bare_fn = TypeBareFn {
+            lifetimes: input.parse()?,
+            unsafety: input.parse()?,
+            abi: input.parse()?,
+            fn_token: input.parse()?,
+            paren_token: parenthesized!(args in input),
+            inputs: {
+                let mut inputs = Punctuated::new();
+
+                while !args.is_empty() {
+                    let attrs = args.call(Attribute::parse_outer)?;
+
+                    if inputs.empty_or_trailing() && args.peek(Token![...]) {
+                        variadic = Some(Variadic {
+                            attrs,
+                            dots: args.parse()?,
+                        });
+                        break;
                     }
-                    allow_variadic = inputs.empty_or_trailing();
-                    inputs
-                },
-                variadic: {
-                    if allow_variadic && args.peek(Token![...]) {
-                        Some(Variadic {
-                            attrs: Vec::new(),
-                            dots: args.parse()?,
-                        })
+
+                    if let Some(arg) = parse_bare_fn_arg(&args, allow_mut_self)? {
+                        inputs.push_value(BareFnArg { attrs, ..arg });
                     } else {
-                        None
+                        has_mut_self = true;
+                    }
+                    if args.is_empty() {
+                        break;
                     }
-                },
-                output: input.call(ReturnType::without_plus)?,
-            })
+
+                    inputs.push_punct(args.parse()?);
+                }
+
+                inputs
+            },
+            variadic,
+            output: input.call(ReturnType::without_plus)?,
+        };
+
+        if has_mut_self {
+            Ok(None)
+        } else {
+            Ok(Some(bare_fn))
         }
     }
 
     impl Parse for TypeNever {
         fn parse(input: ParseStream) -> Result<Self> {
             Ok(TypeNever {
                 bang_token: input.parse()?,
             })
@@ -771,19 +694,37 @@ pub mod parsing {
                 underscore_token: input.parse()?,
             })
         }
     }
 
     impl Parse for TypeTuple {
         fn parse(input: ParseStream) -> Result<Self> {
             let content;
+            let paren_token = parenthesized!(content in input);
+
+            if content.is_empty() {
+                return Ok(TypeTuple {
+                    paren_token,
+                    elems: Punctuated::new(),
+                });
+            }
+
+            let first: Type = content.parse()?;
             Ok(TypeTuple {
-                paren_token: parenthesized!(content in input),
-                elems: content.parse_terminated(Type::parse)?,
+                paren_token,
+                elems: {
+                    let mut elems = Punctuated::new();
+                    elems.push_value(first);
+                    elems.push_punct(content.parse()?);
+                    let rest: Punctuated<Type, Token![,]> =
+                        content.parse_terminated(Parse::parse)?;
+                    elems.extend(rest);
+                    elems
+                },
             })
         }
     }
 
     impl Parse for TypeMacro {
         fn parse(input: ParseStream) -> Result<Self> {
             Ok(TypeMacro {
                 mac: input.parse()?,
@@ -802,19 +743,21 @@ pub mod parsing {
             }
 
             Ok(TypePath { qself, path })
         }
     }
 
     impl ReturnType {
         pub fn without_plus(input: ParseStream) -> Result<Self> {
-            Self::parse(input, false)
+            let allow_plus = false;
+            Self::parse(input, allow_plus)
         }
 
+        #[doc(hidden)]
         pub fn parse(input: ParseStream, allow_plus: bool) -> Result<Self> {
             if input.peek(Token![->]) {
                 let arrow = input.parse()?;
                 let ty = ambig_ty(input, allow_plus)?;
                 Ok(ReturnType::Type(arrow, Box::new(ty)))
             } else {
                 Ok(ReturnType::Default)
             }
@@ -839,20 +782,22 @@ pub mod parsing {
                 return true;
             }
         }
         false
     }
 
     impl TypeTraitObject {
         pub fn without_plus(input: ParseStream) -> Result<Self> {
-            Self::parse(input, false)
+            let allow_plus = false;
+            Self::parse(input, allow_plus)
         }
 
         // Only allow multiple trait references if allow_plus is true.
+        #[doc(hidden)]
         pub fn parse(input: ParseStream, allow_plus: bool) -> Result<Self> {
             Ok(TypeTraitObject {
                 dyn_token: input.parse()?,
                 bounds: {
                     let mut bounds = Punctuated::new();
                     if allow_plus {
                         loop {
                             bounds.push_value(input.parse()?);
@@ -905,48 +850,99 @@ pub mod parsing {
                 group_token: group.token,
                 elem: group.content.parse()?,
             })
         }
     }
 
     impl Parse for TypeParen {
         fn parse(input: ParseStream) -> Result<Self> {
-            Self::parse(input, false)
+            let allow_plus = false;
+            Self::parse(input, allow_plus)
         }
     }
 
     impl TypeParen {
         fn parse(input: ParseStream, allow_plus: bool) -> Result<Self> {
             let content;
             Ok(TypeParen {
                 paren_token: parenthesized!(content in input),
                 elem: Box::new(ambig_ty(&content, allow_plus)?),
             })
         }
     }
 
     impl Parse for BareFnArg {
         fn parse(input: ParseStream) -> Result<Self> {
-            Ok(BareFnArg {
-                attrs: input.call(Attribute::parse_outer)?,
-                name: {
-                    if (input.peek(Ident) || input.peek(Token![_]))
-                        && input.peek2(Token![:])
-                        && !input.peek2(Token![::])
-                    {
-                        let name = input.call(Ident::parse_any)?;
-                        let colon: Token![:] = input.parse()?;
-                        Some((name, colon))
-                    } else {
-                        None
-                    }
-                },
-                ty: input.parse()?,
-            })
+            let allow_mut_self = false;
+            parse_bare_fn_arg(input, allow_mut_self).map(Option::unwrap)
+        }
+    }
+
+    fn parse_bare_fn_arg(
+        input: ParseStream,
+        mut allow_mut_self: bool,
+    ) -> Result<Option<BareFnArg>> {
+        let mut has_mut_self = false;
+        let arg = BareFnArg {
+            attrs: input.call(Attribute::parse_outer)?,
+            name: {
+                if (input.peek(Ident) || input.peek(Token![_]) || input.peek(Token![self]))
+                    && input.peek2(Token![:])
+                    && !input.peek2(Token![::])
+                {
+                    let name = input.call(Ident::parse_any)?;
+                    let colon: Token![:] = input.parse()?;
+                    Some((name, colon))
+                } else if allow_mut_self
+                    && input.peek(Token![mut])
+                    && input.peek2(Token![self])
+                    && input.peek3(Token![:])
+                    && !input.peek3(Token![::])
+                {
+                    has_mut_self = true;
+                    allow_mut_self = false;
+                    input.parse::<Token![mut]>()?;
+                    input.parse::<Token![self]>()?;
+                    input.parse::<Token![:]>()?;
+                    None
+                } else {
+                    None
+                }
+            },
+            ty: if !has_mut_self && input.peek(Token![...]) {
+                let dot3 = input.parse::<Token![...]>()?;
+                let args = vec![
+                    TokenTree::Punct(Punct::new('.', Spacing::Joint)),
+                    TokenTree::Punct(Punct::new('.', Spacing::Joint)),
+                    TokenTree::Punct(Punct::new('.', Spacing::Alone)),
+                ];
+                let tokens = TokenStream::from_iter(args.into_iter().zip(&dot3.spans).map(
+                    |(mut arg, span)| {
+                        arg.set_span(*span);
+                        arg
+                    },
+                ));
+                Type::Verbatim(tokens)
+            } else if allow_mut_self && input.peek(Token![mut]) && input.peek2(Token![self]) {
+                has_mut_self = true;
+                input.parse::<Token![mut]>()?;
+                Type::Path(TypePath {
+                    qself: None,
+                    path: input.parse::<Token![self]>()?.into(),
+                })
+            } else {
+                input.parse()?
+            },
+        };
+
+        if has_mut_self {
+            Ok(None)
+        } else {
+            Ok(Some(arg))
         }
     }
 
     impl Parse for Abi {
         fn parse(input: ParseStream) -> Result<Self> {
             Ok(Abi {
                 extern_token: input.parse()?,
                 name: input.parse()?,
diff --git a/third_party/rust/syn/src/verbatim.rs b/third_party/rust/syn/src/verbatim.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/src/verbatim.rs
@@ -0,0 +1,15 @@
+use crate::parse::{ParseBuffer, ParseStream};
+use proc_macro2::TokenStream;
+use std::iter;
+
+pub fn between<'a>(begin: ParseBuffer<'a>, end: ParseStream<'a>) -> TokenStream {
+    let end = end.cursor();
+    let mut cursor = begin.cursor();
+    let mut tokens = TokenStream::new();
+    while cursor != end {
+        let (tt, next) = cursor.token_tree().unwrap();
+        tokens.extend(iter::once(tt));
+        cursor = next;
+    }
+    tokens
+}
diff --git a/third_party/rust/syn/src/whitespace.rs b/third_party/rust/syn/src/whitespace.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/src/whitespace.rs
@@ -0,0 +1,65 @@
+pub fn skip(mut s: &str) -> &str {
+    'skip: while !s.is_empty() {
+        let byte = s.as_bytes()[0];
+        if byte == b'/' {
+            if s.starts_with("//")
+                && (!s.starts_with("///") || s.starts_with("////"))
+                && !s.starts_with("//!")
+            {
+                if let Some(i) = s.find('\n') {
+                    s = &s[i + 1..];
+                    continue;
+                } else {
+                    return "";
+                }
+            } else if s.starts_with("/**/") {
+                s = &s[4..];
+                continue;
+            } else if s.starts_with("/*")
+                && (!s.starts_with("/**") || s.starts_with("/***"))
+                && !s.starts_with("/*!")
+            {
+                let mut depth = 0;
+                let bytes = s.as_bytes();
+                let mut i = 0;
+                let upper = bytes.len() - 1;
+                while i < upper {
+                    if bytes[i] == b'/' && bytes[i + 1] == b'*' {
+                        depth += 1;
+                        i += 1; // eat '*'
+                    } else if bytes[i] == b'*' && bytes[i + 1] == b'/' {
+                        depth -= 1;
+                        if depth == 0 {
+                            s = &s[i + 2..];
+                            continue 'skip;
+                        }
+                        i += 1; // eat '/'
+                    }
+                    i += 1;
+                }
+                return s;
+            }
+        }
+        match byte {
+            b' ' | 0x09..=0x0d => {
+                s = &s[1..];
+                continue;
+            }
+            b if b <= 0x7f => {}
+            _ => {
+                let ch = s.chars().next().unwrap();
+                if is_whitespace(ch) {
+                    s = &s[ch.len_utf8()..];
+                    continue;
+                }
+            }
+        }
+        return s;
+    }
+    s
+}
+
+fn is_whitespace(ch: char) -> bool {
+    // Rust treats left-to-right mark and right-to-left mark as whitespace
+    ch.is_whitespace() || ch == '\u{200e}' || ch == '\u{200f}'
+}
diff --git a/third_party/rust/syn/tests/.gitignore b/third_party/rust/syn/tests/.gitignore
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/tests/.gitignore
@@ -0,0 +1,1 @@
+/*.pending-snap
diff --git a/third_party/rust/syn/tests/clone.sh b/third_party/rust/syn/tests/clone.sh
deleted file mode 100755
--- a/third_party/rust/syn/tests/clone.sh
+++ /dev/null
@@ -1,16 +0,0 @@
-#!/bin/bash
-
-REV=4560cb830fce63fcffdc4558f4281aaac6a3a1ba
-
-set -euo pipefail
-cd "$(dirname "${BASH_SOURCE[0]}")"
-mkdir -p rust
-touch rust/COMMIT
-
-if [ "$(cat rust/COMMIT)" != "$REV" ]; then
-    rm -rf rust
-    mkdir rust
-    curl -L "https://github.com/rust-lang/rust/archive/${REV}.tar.gz" \
-        | tar xz --directory rust --strip-components 1
-    echo "$REV" > rust/COMMIT
-fi
diff --git a/third_party/rust/syn/tests/common/eq.rs b/third_party/rust/syn/tests/common/eq.rs
--- a/third_party/rust/syn/tests/common/eq.rs
+++ b/third_party/rust/syn/tests/common/eq.rs
@@ -1,41 +1,40 @@
+extern crate rustc_ast;
 extern crate rustc_data_structures;
+extern crate rustc_span;
 extern crate rustc_target;
-extern crate syntax;
-extern crate syntax_pos;
 
 use std::mem;
 
-use self::rustc_data_structures::sync::Lrc;
-use self::rustc_data_structures::thin_vec::ThinVec;
-use self::rustc_target::abi::FloatTy;
-use self::rustc_target::spec::abi::Abi;
-use self::syntax::ast::{
-    AngleBracketedArgs, AnonConst, Arg, Arm, AsmDialect, AssocTyConstraint, AssocTyConstraintKind,
-    AttrId, AttrStyle, Attribute, BareFnTy, BinOpKind, BindingMode, Block, BlockCheckMode,
-    CaptureBy, Constness, Crate, CrateSugar, Defaultness, EnumDef, Expr, ExprKind, Field, FieldPat,
-    FnDecl, FnHeader, ForeignItem, ForeignItemKind, ForeignMod, FunctionRetTy, GenericArg,
-    GenericArgs, GenericBound, GenericParam, GenericParamKind, Generics, GlobalAsm, Ident,
-    ImplItem, ImplItemKind, ImplPolarity, InlineAsm, InlineAsmOutput, IntTy, IsAsync, IsAuto, Item,
-    ItemKind, Label, Lifetime, Lit, LitIntType, LitKind, Local, Mac, MacDelimiter, MacStmtStyle,
-    MacroDef, MethodSig, Mod, Movability, MutTy, Mutability, NodeId, ParenthesizedArgs, Pat,
-    PatKind, Path, PathSegment, PolyTraitRef, QSelf, RangeEnd, RangeLimits, RangeSyntax, Stmt,
-    StmtKind, StrStyle, StructField, TraitBoundModifier, TraitItem, TraitItemKind,
-    TraitObjectSyntax, TraitRef, Ty, TyKind, UintTy, UnOp, UnsafeSource, Unsafety, UseTree,
-    UseTreeKind, Variant, VariantData, VisibilityKind, WhereBoundPredicate, WhereClause,
-    WhereEqPredicate, WherePredicate, WhereRegionPredicate,
+use rustc_ast::ast::{
+    AngleBracketedArg, AngleBracketedArgs, AnonConst, Arm, AssocItemKind, AssocTyConstraint,
+    AssocTyConstraintKind, Async, AttrId, AttrItem, AttrKind, AttrStyle, Attribute, BareFnTy,
+    BinOpKind, BindingMode, Block, BlockCheckMode, BorrowKind, CaptureBy, Const, Crate, CrateSugar,
+    Defaultness, EnumDef, Expr, ExprKind, Extern, Field, FieldPat, FloatTy, FnDecl, FnHeader,
+    FnRetTy, FnSig, ForeignItemKind, ForeignMod, GenericArg, GenericArgs, GenericBound,
+    GenericParam, GenericParamKind, Generics, GlobalAsm, ImplPolarity, InlineAsm, InlineAsmOperand,
+    InlineAsmOptions, InlineAsmRegOrRegClass, InlineAsmTemplatePiece, IntTy, IsAuto, Item,
+    ItemKind, Label, Lifetime, Lit, LitFloatType, LitIntType, LitKind, LlvmAsmDialect,
+    LlvmInlineAsm, LlvmInlineAsmOutput, Local, MacArgs, MacCall, MacCallStmt, MacDelimiter,
+    MacStmtStyle, MacroDef, Mod, Movability, MutTy, Mutability, NodeId, Param, ParenthesizedArgs,
+    Pat, PatKind, Path, PathSegment, PolyTraitRef, QSelf, RangeEnd, RangeLimits, RangeSyntax, Stmt,
+    StmtKind, StrLit, StrStyle, StructField, TraitBoundModifier, TraitObjectSyntax, TraitRef, Ty,
+    TyKind, UintTy, UnOp, Unsafe, UnsafeSource, UseTree, UseTreeKind, Variant, VariantData,
+    VisibilityKind, WhereBoundPredicate, WhereClause, WhereEqPredicate, WherePredicate,
+    WhereRegionPredicate,
 };
-use self::syntax::parse::lexer::comments;
-use self::syntax::parse::token::{self, DelimToken, Token, TokenKind};
-use self::syntax::ptr::P;
-use self::syntax::source_map::Spanned;
-use self::syntax::symbol::{sym, Symbol};
-use self::syntax::tokenstream::{DelimSpan, TokenStream, TokenTree};
-use self::syntax_pos::{Span, SyntaxContext, DUMMY_SP};
+use rustc_ast::ptr::P;
+use rustc_ast::token::{self, CommentKind, DelimToken, Token, TokenKind};
+use rustc_ast::tokenstream::{DelimSpan, TokenStream, TokenTree};
+use rustc_data_structures::sync::Lrc;
+use rustc_data_structures::thin_vec::ThinVec;
+use rustc_span::source_map::Spanned;
+use rustc_span::symbol::Ident;
+use rustc_span::{Span, Symbol, SyntaxContext};
 
 pub trait SpanlessEq {
     fn eq(&self, other: &Self) -> bool;
 }
 
 impl<T: SpanlessEq> SpanlessEq for P<T> {
     fn eq(&self, other: &Self) -> bool {
         SpanlessEq::eq(&**self, &**other)
@@ -81,24 +80,16 @@ impl<T: SpanlessEq> SpanlessEq for Spann
 }
 
 impl<A: SpanlessEq, B: SpanlessEq> SpanlessEq for (A, B) {
     fn eq(&self, other: &Self) -> bool {
         SpanlessEq::eq(&self.0, &other.0) && SpanlessEq::eq(&self.1, &other.1)
     }
 }
 
-impl<A: SpanlessEq, B: SpanlessEq, C: SpanlessEq> SpanlessEq for (A, B, C) {
-    fn eq(&self, other: &Self) -> bool {
-        SpanlessEq::eq(&self.0, &other.0)
-            && SpanlessEq::eq(&self.1, &other.1)
-            && SpanlessEq::eq(&self.2, &other.2)
-    }
-}
-
 macro_rules! spanless_eq_true {
     ($name:ident) => {
         impl SpanlessEq for $name {
             fn eq(&self, _other: &Self) -> bool {
                 true
             }
         }
     };
@@ -121,60 +112,62 @@ macro_rules! spanless_eq_partial_eq {
 }
 
 spanless_eq_partial_eq!(bool);
 spanless_eq_partial_eq!(u8);
 spanless_eq_partial_eq!(u16);
 spanless_eq_partial_eq!(u128);
 spanless_eq_partial_eq!(usize);
 spanless_eq_partial_eq!(char);
+spanless_eq_partial_eq!(String);
 spanless_eq_partial_eq!(Symbol);
-spanless_eq_partial_eq!(Abi);
+spanless_eq_partial_eq!(CommentKind);
 spanless_eq_partial_eq!(DelimToken);
+spanless_eq_partial_eq!(InlineAsmOptions);
 
 macro_rules! spanless_eq_struct {
     {
-        $name:ident;
+        $name:ident $(<$param:ident>)?;
         $([$field:ident $other:ident])*
         $(![$ignore:ident])*
     } => {
-        impl SpanlessEq for $name {
+        impl $(<$param: SpanlessEq>)* SpanlessEq for $name $(<$param>)* {
             fn eq(&self, other: &Self) -> bool {
                 let $name { $($field,)* $($ignore: _,)* } = self;
                 let $name { $($field: $other,)* $($ignore: _,)* } = other;
                 $(SpanlessEq::eq($field, $other))&&*
             }
         }
     };
 
     {
-        $name:ident;
+        $name:ident $(<$param:ident>)?;
         $([$field:ident $other:ident])*
         $next:ident
         $($rest:ident)*
         $(!$ignore:ident)*
     } => {
         spanless_eq_struct! {
-            $name;
+            $name $(<$param>)*;
             $([$field $other])*
             [$next other]
             $($rest)*
             $(!$ignore)*
         }
     };
 
     {
-        $name:ident;
+        $name:ident $(<$param:ident>)?;
         $([$field:ident $other:ident])*
         $(![$ignore:ident])*
         !$next:ident
         $(!$rest:ident)*
     } => {
         spanless_eq_struct! {
-            $name;
+            $name $(<$param>)*;
             $([$field $other])*
             $(![$ignore])*
             ![$next]
             $(!$rest)*
         }
     };
 }
 
@@ -258,129 +251,141 @@ macro_rules! spanless_eq_enum {
             $name;
             $([$variant $($fields)*])*
             [$next]
             $($rest)*
         }
     };
 }
 
-spanless_eq_struct!(AngleBracketedArgs; span args constraints);
+spanless_eq_struct!(AngleBracketedArgs; span args);
 spanless_eq_struct!(AnonConst; id value);
-spanless_eq_struct!(Arg; attrs ty pat id span);
-spanless_eq_struct!(Arm; attrs pats guard body span id);
+spanless_eq_struct!(Arm; attrs pat guard body span id is_placeholder);
 spanless_eq_struct!(AssocTyConstraint; id ident kind span);
-spanless_eq_struct!(Attribute; id style path tokens span !is_sugared_doc);
-spanless_eq_struct!(BareFnTy; unsafety abi generic_params decl);
+spanless_eq_struct!(AttrItem; path args);
+spanless_eq_struct!(Attribute; kind id style span);
+spanless_eq_struct!(BareFnTy; unsafety ext generic_params decl);
 spanless_eq_struct!(Block; stmts id rules span);
-spanless_eq_struct!(Crate; module attrs span);
+spanless_eq_struct!(Crate; module attrs span proc_macros);
 spanless_eq_struct!(EnumDef; variants);
-spanless_eq_struct!(Expr; id node span attrs);
-spanless_eq_struct!(Field; ident expr span is_shorthand attrs id);
-spanless_eq_struct!(FieldPat; ident pat is_shorthand attrs id span);
-spanless_eq_struct!(FnDecl; inputs output c_variadic);
-spanless_eq_struct!(FnHeader; constness asyncness unsafety abi);
-spanless_eq_struct!(ForeignItem; ident attrs node id span vis);
+spanless_eq_struct!(Expr; id kind span attrs !tokens);
+spanless_eq_struct!(Field; attrs id span ident expr is_shorthand is_placeholder);
+spanless_eq_struct!(FieldPat; ident pat is_shorthand attrs id span is_placeholder);
+spanless_eq_struct!(FnDecl; inputs output);
+spanless_eq_struct!(FnHeader; constness asyncness unsafety ext);
+spanless_eq_struct!(FnSig; header decl span);
 spanless_eq_struct!(ForeignMod; abi items);
-spanless_eq_struct!(GenericParam; id ident attrs bounds kind);
+spanless_eq_struct!(GenericParam; id ident attrs bounds is_placeholder kind);
 spanless_eq_struct!(Generics; params where_clause span);
 spanless_eq_struct!(GlobalAsm; asm);
-spanless_eq_struct!(ImplItem; id ident vis defaultness attrs generics node span !tokens);
-spanless_eq_struct!(InlineAsm; asm asm_str_style outputs inputs clobbers volatile alignstack dialect);
-spanless_eq_struct!(InlineAsmOutput; constraint expr is_rw is_indirect);
-spanless_eq_struct!(Item; ident attrs id node vis span !tokens);
+spanless_eq_struct!(InlineAsm; template operands options line_spans);
+spanless_eq_struct!(Item<K>; attrs id span vis ident kind !tokens);
 spanless_eq_struct!(Label; ident);
 spanless_eq_struct!(Lifetime; id ident);
-spanless_eq_struct!(Lit; token node span);
+spanless_eq_struct!(Lit; token kind span);
+spanless_eq_struct!(LlvmInlineAsm; asm asm_str_style outputs inputs clobbers volatile alignstack dialect);
+spanless_eq_struct!(LlvmInlineAsmOutput; constraint expr is_rw is_indirect);
 spanless_eq_struct!(Local; pat ty init id span attrs);
-spanless_eq_struct!(Mac; path delim tts span prior_type_ascription);
-spanless_eq_struct!(MacroDef; tokens legacy);
-spanless_eq_struct!(MethodSig; header decl);
+spanless_eq_struct!(MacCall; path args prior_type_ascription);
+spanless_eq_struct!(MacCallStmt; mac style attrs);
+spanless_eq_struct!(MacroDef; body macro_rules);
 spanless_eq_struct!(Mod; inner items inline);
 spanless_eq_struct!(MutTy; ty mutbl);
+spanless_eq_struct!(Param; attrs ty pat id span is_placeholder);
 spanless_eq_struct!(ParenthesizedArgs; span inputs output);
-spanless_eq_struct!(Pat; id node span);
+spanless_eq_struct!(Pat; id kind span tokens);
 spanless_eq_struct!(Path; span segments);
 spanless_eq_struct!(PathSegment; ident id args);
 spanless_eq_struct!(PolyTraitRef; bound_generic_params trait_ref span);
 spanless_eq_struct!(QSelf; ty path_span position);
-spanless_eq_struct!(Stmt; id node span);
-spanless_eq_struct!(StructField; span ident vis id ty attrs);
+spanless_eq_struct!(Stmt; id kind span);
+spanless_eq_struct!(StrLit; style symbol suffix span symbol_unescaped);
+spanless_eq_struct!(StructField; attrs id span vis ident ty is_placeholder);
 spanless_eq_struct!(Token; kind span);
-spanless_eq_struct!(TraitItem; id ident attrs generics node span !tokens);
 spanless_eq_struct!(TraitRef; path ref_id);
-spanless_eq_struct!(Ty; id node span);
+spanless_eq_struct!(Ty; id kind span);
 spanless_eq_struct!(UseTree; prefix kind span);
-spanless_eq_struct!(Variant; ident attrs id data disr_expr span);
+spanless_eq_struct!(Variant; attrs id span vis ident data disr_expr is_placeholder);
 spanless_eq_struct!(WhereBoundPredicate; span bound_generic_params bounded_ty bounds);
-spanless_eq_struct!(WhereClause; predicates span);
+spanless_eq_struct!(WhereClause; has_where_token predicates span);
 spanless_eq_struct!(WhereEqPredicate; id span lhs_ty rhs_ty);
 spanless_eq_struct!(WhereRegionPredicate; span lifetime bounds);
-spanless_eq_enum!(AsmDialect; Att Intel);
+spanless_eq_enum!(AngleBracketedArg; Arg(0) Constraint(0));
+spanless_eq_enum!(AssocItemKind; Const(0 1 2) Fn(0 1 2 3) TyAlias(0 1 2 3) MacCall(0));
 spanless_eq_enum!(AssocTyConstraintKind; Equality(ty) Bound(bounds));
+spanless_eq_enum!(Async; Yes(span closure_id return_impl_trait_id) No);
+spanless_eq_enum!(AttrKind; Normal(0) DocComment(0 1));
 spanless_eq_enum!(AttrStyle; Outer Inner);
 spanless_eq_enum!(BinOpKind; Add Sub Mul Div Rem And Or BitXor BitAnd BitOr Shl Shr Eq Lt Le Ne Ge Gt);
 spanless_eq_enum!(BindingMode; ByRef(0) ByValue(0));
 spanless_eq_enum!(BlockCheckMode; Default Unsafe(0));
+spanless_eq_enum!(BorrowKind; Ref Raw);
 spanless_eq_enum!(CaptureBy; Value Ref);
-spanless_eq_enum!(Constness; Const NotConst);
+spanless_eq_enum!(Const; Yes(0) No);
 spanless_eq_enum!(CrateSugar; PubCrate JustCrate);
-spanless_eq_enum!(Defaultness; Default Final);
+spanless_eq_enum!(Defaultness; Default(0) Final);
+spanless_eq_enum!(Extern; None Implicit Explicit(0));
 spanless_eq_enum!(FloatTy; F32 F64);
-spanless_eq_enum!(ForeignItemKind; Fn(0 1) Static(0 1) Ty Macro(0));
-spanless_eq_enum!(FunctionRetTy; Default(0) Ty(0));
+spanless_eq_enum!(FnRetTy; Default(0) Ty(0));
+spanless_eq_enum!(ForeignItemKind; Static(0 1 2) Fn(0 1 2 3) TyAlias(0 1 2 3) MacCall(0));
 spanless_eq_enum!(GenericArg; Lifetime(0) Type(0) Const(0));
 spanless_eq_enum!(GenericArgs; AngleBracketed(0) Parenthesized(0));
 spanless_eq_enum!(GenericBound; Trait(0 1) Outlives(0));
-spanless_eq_enum!(GenericParamKind; Lifetime Type(default) Const(ty));
-spanless_eq_enum!(ImplItemKind; Const(0 1) Method(0 1) TyAlias(0) OpaqueTy(0) Macro(0));
-spanless_eq_enum!(ImplPolarity; Positive Negative);
+spanless_eq_enum!(GenericParamKind; Lifetime Type(default) Const(ty kw_span));
+spanless_eq_enum!(ImplPolarity; Positive Negative(0));
+spanless_eq_enum!(InlineAsmRegOrRegClass; Reg(0) RegClass(0));
+spanless_eq_enum!(InlineAsmTemplatePiece; String(0) Placeholder(operand_idx modifier span));
 spanless_eq_enum!(IntTy; Isize I8 I16 I32 I64 I128);
-spanless_eq_enum!(IsAsync; Async(closure_id return_impl_trait_id) NotAsync);
 spanless_eq_enum!(IsAuto; Yes No);
+spanless_eq_enum!(LitFloatType; Suffixed(0) Unsuffixed);
 spanless_eq_enum!(LitIntType; Signed(0) Unsigned(0) Unsuffixed);
+spanless_eq_enum!(LlvmAsmDialect; Att Intel);
+spanless_eq_enum!(MacArgs; Empty Delimited(0 1 2) Eq(0 1));
 spanless_eq_enum!(MacDelimiter; Parenthesis Bracket Brace);
 spanless_eq_enum!(MacStmtStyle; Semicolon Braces NoBraces);
 spanless_eq_enum!(Movability; Static Movable);
-spanless_eq_enum!(Mutability; Mutable Immutable);
+spanless_eq_enum!(Mutability; Mut Not);
 spanless_eq_enum!(RangeEnd; Included(0) Excluded);
 spanless_eq_enum!(RangeLimits; HalfOpen Closed);
-spanless_eq_enum!(StmtKind; Local(0) Item(0) Expr(0) Semi(0) Mac(0));
+spanless_eq_enum!(StmtKind; Local(0) Item(0) Expr(0) Semi(0) Empty MacCall(0));
 spanless_eq_enum!(StrStyle; Cooked Raw(0));
 spanless_eq_enum!(TokenTree; Token(0) Delimited(0 1 2));
-spanless_eq_enum!(TraitBoundModifier; None Maybe);
-spanless_eq_enum!(TraitItemKind; Const(0 1) Method(0 1) Type(0 1) Macro(0));
+spanless_eq_enum!(TraitBoundModifier; None Maybe MaybeConst MaybeConstMaybe);
 spanless_eq_enum!(TraitObjectSyntax; Dyn None);
 spanless_eq_enum!(UintTy; Usize U8 U16 U32 U64 U128);
 spanless_eq_enum!(UnOp; Deref Not Neg);
+spanless_eq_enum!(Unsafe; Yes(0) No);
 spanless_eq_enum!(UnsafeSource; CompilerGenerated UserProvided);
-spanless_eq_enum!(Unsafety; Unsafe Normal);
 spanless_eq_enum!(UseTreeKind; Simple(0 1 2) Nested(0) Glob);
 spanless_eq_enum!(VariantData; Struct(0 1) Tuple(0 1) Unit(0));
 spanless_eq_enum!(VisibilityKind; Public Crate(0) Restricted(path id) Inherited);
 spanless_eq_enum!(WherePredicate; BoundPredicate(0) RegionPredicate(0) EqPredicate(0));
-spanless_eq_enum!(ExprKind; Box(0) Array(0) Call(0 1) MethodCall(0 1) Tup(0)
+spanless_eq_enum!(ExprKind; Box(0) Array(0) Call(0 1) MethodCall(0 1 2) Tup(0)
     Binary(0 1 2) Unary(0 1) Lit(0) Cast(0 1) Type(0 1) Let(0 1) If(0 1 2)
     While(0 1 2) ForLoop(0 1 2 3) Loop(0 1) Match(0 1) Closure(0 1 2 3 4 5)
-    Block(0 1) Async(0 1 2) Await(0) TryBlock(0) Assign(0 1) AssignOp(0 1 2)
-    Field(0 1) Index(0 1) Range(0 1 2) Path(0 1) AddrOf(0 1) Break(0 1)
-    Continue(0) Ret(0) InlineAsm(0) Mac(0) Struct(0 1 2) Repeat(0 1) Paren(0)
-    Try(0) Yield(0) Err);
-spanless_eq_enum!(ItemKind; ExternCrate(0) Use(0) Static(0 1 2) Const(0 1)
-    Fn(0 1 2 3) Mod(0) ForeignMod(0) GlobalAsm(0) TyAlias(0 1) OpaqueTy(0 1)
-    Enum(0 1) Struct(0 1) Union(0 1) Trait(0 1 2 3 4) TraitAlias(0 1)
-    Impl(0 1 2 3 4 5 6) Mac(0) MacroDef(0));
+    Block(0 1) Async(0 1 2) Await(0) TryBlock(0) Assign(0 1 2) AssignOp(0 1 2)
+    Field(0 1) Index(0 1) Range(0 1 2) Path(0 1) AddrOf(0 1 2) Break(0 1)
+    Continue(0) Ret(0) InlineAsm(0) LlvmInlineAsm(0) MacCall(0) Struct(0 1 2)
+    Repeat(0 1) Paren(0) Try(0) Yield(0) Err);
+spanless_eq_enum!(InlineAsmOperand; In(reg expr) Out(reg late expr)
+    InOut(reg late expr) SplitInOut(reg late in_expr out_expr) Const(expr)
+    Sym(expr));
+spanless_eq_enum!(ItemKind; ExternCrate(0) Use(0) Static(0 1 2) Const(0 1 2)
+    Fn(0 1 2 3) Mod(0) ForeignMod(0) GlobalAsm(0) TyAlias(0 1 2 3) Enum(0 1)
+    Struct(0 1) Union(0 1) Trait(0 1 2 3 4) TraitAlias(0 1)
+    Impl(unsafety polarity defaultness constness generics of_trait self_ty items)
+    MacCall(0) MacroDef(0));
 spanless_eq_enum!(LitKind; Str(0 1) ByteStr(0) Byte(0) Char(0) Int(0 1)
-    Float(0 1) FloatUnsuffixed(0) Bool(0) Err(0));
+    Float(0 1) Bool(0) Err(0));
 spanless_eq_enum!(PatKind; Wild Ident(0 1 2) Struct(0 1 2) TupleStruct(0 1)
     Or(0) Path(0 1) Tuple(0) Box(0) Ref(0 1) Lit(0) Range(0 1 2) Slice(0) Rest
-    Paren(0) Mac(0));
+    Paren(0) MacCall(0));
 spanless_eq_enum!(TyKind; Slice(0) Array(0 1) Ptr(0) Rptr(0 1) BareFn(0) Never
     Tup(0) Path(0 1) TraitObject(0 1) ImplTrait(0 1) Paren(0) Typeof(0) Infer
-    ImplicitSelf Mac(0) Err CVarArgs);
+    ImplicitSelf MacCall(0) Err CVarArgs);
 
 impl SpanlessEq for Ident {
     fn eq(&self, other: &Self) -> bool {
         self.as_str() == other.as_str()
     }
 }
 
 // Give up on comparing literals inside of macros because there are so many
@@ -409,49 +414,25 @@ impl SpanlessEq for TokenKind {
             },
             _ => self == other,
         }
     }
 }
 
 impl SpanlessEq for TokenStream {
     fn eq(&self, other: &Self) -> bool {
-        SpanlessEq::eq(&expand_tts(self), &expand_tts(other))
+        let mut this = self.clone().into_trees();
+        let mut other = other.clone().into_trees();
+        loop {
+            let this = match this.next() {
+                None => return other.next().is_none(),
+                Some(val) => val,
+            };
+            let other = match other.next() {
+                None => return false,
+                Some(val) => val,
+            };
+            if !SpanlessEq::eq(&this, &other) {
+                return false;
+            }
+        }
     }
 }
-
-fn expand_tts(tts: &TokenStream) -> Vec<TokenTree> {
-    let mut tokens = Vec::new();
-    for tt in tts.clone().into_trees() {
-        let c = match tt {
-            TokenTree::Token(Token {
-                kind: TokenKind::DocComment(c),
-                ..
-            }) => c,
-            _ => {
-                tokens.push(tt);
-                continue;
-            }
-        };
-        let contents = comments::strip_doc_comment_decoration(&c.as_str());
-        let style = comments::doc_comment_style(&c.as_str());
-        tokens.push(TokenTree::token(TokenKind::Pound, DUMMY_SP));
-        if style == AttrStyle::Inner {
-            tokens.push(TokenTree::token(TokenKind::Not, DUMMY_SP));
-        }
-        let lit = token::Lit {
-            kind: token::LitKind::Str,
-            symbol: Symbol::intern(&contents),
-            suffix: None,
-        };
-        let tts = vec![
-            TokenTree::token(TokenKind::Ident(sym::doc, false), DUMMY_SP),
-            TokenTree::token(TokenKind::Eq, DUMMY_SP),
-            TokenTree::token(TokenKind::Literal(lit), DUMMY_SP),
-        ];
-        tokens.push(TokenTree::Delimited(
-            DelimSpan::dummy(),
-            DelimToken::Bracket,
-            tts.into_iter().collect::<TokenStream>().into(),
-        ));
-    }
-    tokens
-}
diff --git a/third_party/rust/syn/tests/common/mod.rs b/third_party/rust/syn/tests/common/mod.rs
--- a/third_party/rust/syn/tests/common/mod.rs
+++ b/third_party/rust/syn/tests/common/mod.rs
@@ -1,14 +1,27 @@
 #![allow(dead_code)]
 
+use rayon::ThreadPoolBuilder;
 use std::env;
 
 pub mod eq;
 pub mod parse;
 
 /// Read the `ABORT_AFTER_FAILURE` environment variable, and parse it.
 pub fn abort_after() -> usize {
     match env::var("ABORT_AFTER_FAILURE") {
         Ok(s) => s.parse().expect("failed to parse ABORT_AFTER_FAILURE"),
         Err(_) => usize::max_value(),
     }
 }
+
+/// Configure Rayon threadpool.
+pub fn rayon_init() {
+    let stack_size = match env::var("RUST_MIN_STACK") {
+        Ok(s) => s.parse().expect("failed to parse RUST_MIN_STACK"),
+        Err(_) => 20 * 1024 * 1024,
+    };
+    ThreadPoolBuilder::new()
+        .stack_size(stack_size)
+        .build_global()
+        .unwrap();
+}
diff --git a/third_party/rust/syn/tests/common/parse.rs b/third_party/rust/syn/tests/common/parse.rs
--- a/third_party/rust/syn/tests/common/parse.rs
+++ b/third_party/rust/syn/tests/common/parse.rs
@@ -1,25 +1,25 @@
-extern crate proc_macro2;
-extern crate syn;
-extern crate syntax;
-extern crate syntax_pos;
+extern crate rustc_ast;
+extern crate rustc_expand;
+extern crate rustc_parse as parse;
+extern crate rustc_session;
+extern crate rustc_span;
 
-use self::syntax::ast;
-use self::syntax::parse::{self, ParseSess};
-use self::syntax::ptr::P;
-use self::syntax::source_map::FilePathMapping;
-use self::syntax_pos::FileName;
+use rustc_ast::ast;
+use rustc_ast::ptr::P;
+use rustc_session::parse::ParseSess;
+use rustc_span::source_map::FilePathMapping;
+use rustc_span::FileName;
 
 use std::panic;
 
-pub fn libsyntax_expr(input: &str) -> Option<P<ast::Expr>> {
+pub fn librustc_expr(input: &str) -> Option<P<ast::Expr>> {
     match panic::catch_unwind(|| {
         let sess = ParseSess::new(FilePathMapping::empty());
-        sess.span_diagnostic.set_continue_after_error(false);
         let e = parse::new_parser_from_source_str(
             &sess,
             FileName::Custom("test_precedence".to_string()),
             input.to_string(),
         )
         .parse_expr();
         match e {
             Ok(expr) => Some(expr),
@@ -27,17 +27,17 @@ pub fn libsyntax_expr(input: &str) -> Op
                 diagnostic.emit();
                 None
             }
         }
     }) {
         Ok(Some(e)) => Some(e),
         Ok(None) => None,
         Err(_) => {
-            errorf!("libsyntax panicked\n");
+            errorf!("librustc panicked\n");
             None
         }
     }
 }
 
 pub fn syn_expr(input: &str) -> Option<syn::Expr> {
     match syn::parse_str(input) {
         Ok(e) => Some(e),
diff --git a/third_party/rust/syn/tests/debug/gen.rs b/third_party/rust/syn/tests/debug/gen.rs
--- a/third_party/rust/syn/tests/debug/gen.rs
+++ b/third_party/rust/syn/tests/debug/gen.rs
@@ -1,13 +1,13 @@
 // This file is @generated by syn-internal-codegen.
 // It is not intended for manual editing.
 
 use super::{Lite, RefCast};
-use std::fmt::{self, Debug};
+use std::fmt::{self, Debug, Display};
 impl Debug for Lite<syn::Abi> {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         let _val = &self.value;
         let mut formatter = formatter.debug_struct("Abi");
         if let Some(val) = &_val.name {
             #[derive(RefCast)]
             #[repr(transparent)]
             struct Print(syn::LitStr);
@@ -1034,19 +1034,19 @@ impl Debug for Lite<syn::Expr> {
                 if !_val.attrs.is_empty() {
                     formatter.field("attrs", Lite(&_val.attrs));
                 }
                 formatter.field("block", Lite(&_val.block));
                 formatter.finish()
             }
             syn::Expr::Verbatim(_val) => {
                 formatter.write_str("Verbatim")?;
-                formatter.write_str("(")?;
-                Debug::fmt(Lite(_val), formatter)?;
-                formatter.write_str(")")?;
+                formatter.write_str("(`")?;
+                Display::fmt(_val, formatter)?;
+                formatter.write_str("`)")?;
                 Ok(())
             }
             syn::Expr::While(_val) => {
                 let mut formatter = formatter.debug_struct("Expr::While");
                 if !_val.attrs.is_empty() {
                     formatter.field("attrs", Lite(&_val.attrs));
                 }
                 if let Some(val) = &_val.label {
@@ -2111,19 +2111,19 @@ impl Debug for Lite<syn::ForeignItem> {
                         }
                     }
                     formatter.field("semi_token", Print::ref_cast(val));
                 }
                 formatter.finish()
             }
             syn::ForeignItem::Verbatim(_val) => {
                 formatter.write_str("Verbatim")?;
-                formatter.write_str("(")?;
-                Debug::fmt(Lite(_val), formatter)?;
-                formatter.write_str(")")?;
+                formatter.write_str("(`")?;
+                Display::fmt(_val, formatter)?;
+                formatter.write_str("`)")?;
                 Ok(())
             }
             _ => unreachable!(),
         }
     }
 }
 impl Debug for Lite<syn::ForeignItemFn> {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
@@ -2427,19 +2427,19 @@ impl Debug for Lite<syn::ImplItem> {
                         }
                     }
                     formatter.field("semi_token", Print::ref_cast(val));
                 }
                 formatter.finish()
             }
             syn::ImplItem::Verbatim(_val) => {
                 formatter.write_str("Verbatim")?;
-                formatter.write_str("(")?;
-                Debug::fmt(Lite(_val), formatter)?;
-                formatter.write_str(")")?;
+                formatter.write_str("(`")?;
+                Display::fmt(_val, formatter)?;
+                formatter.write_str("`)")?;
                 Ok(())
             }
             _ => unreachable!(),
         }
     }
 }
 impl Debug for Lite<syn::ImplItemConst> {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
@@ -2935,19 +2935,19 @@ impl Debug for Lite<syn::Item> {
                     }
                     formatter.field("leading_colon", Print::ref_cast(val));
                 }
                 formatter.field("tree", Lite(&_val.tree));
                 formatter.finish()
             }
             syn::Item::Verbatim(_val) => {
                 formatter.write_str("Verbatim")?;
-                formatter.write_str("(")?;
-                Debug::fmt(Lite(_val), formatter)?;
-                formatter.write_str(")")?;
+                formatter.write_str("(`")?;
+                Display::fmt(_val, formatter)?;
+                formatter.write_str("`)")?;
                 Ok(())
             }
             _ => unreachable!(),
         }
     }
 }
 impl Debug for Lite<syn::ItemConst> {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
@@ -3432,19 +3432,19 @@ impl Debug for Lite<syn::Lit> {
             syn::Lit::Float(_val) => write!(formatter, "{}", _val),
             syn::Lit::Bool(_val) => {
                 let mut formatter = formatter.debug_struct("Lit::Bool");
                 formatter.field("value", Lite(&_val.value));
                 formatter.finish()
             }
             syn::Lit::Verbatim(_val) => {
                 formatter.write_str("Verbatim")?;
-                formatter.write_str("(")?;
-                Debug::fmt(Lite(_val), formatter)?;
-                formatter.write_str(")")?;
+                formatter.write_str("(`")?;
+                Display::fmt(_val, formatter)?;
+                formatter.write_str("`)")?;
                 Ok(())
             }
         }
     }
 }
 impl Debug for Lite<syn::LitBool> {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         let _val = &self.value;
@@ -3873,19 +3873,19 @@ impl Debug for Lite<syn::Pat> {
                     formatter.field("attrs", Lite(&_val.attrs));
                 }
                 formatter.field("pat", Lite(&_val.pat));
                 formatter.field("ty", Lite(&_val.ty));
                 formatter.finish()
             }
             syn::Pat::Verbatim(_val) => {
                 formatter.write_str("Verbatim")?;
-                formatter.write_str("(")?;
-                Debug::fmt(Lite(_val), formatter)?;
-                formatter.write_str(")")?;
+                formatter.write_str("(`")?;
+                Display::fmt(_val, formatter)?;
+                formatter.write_str("`)")?;
                 Ok(())
             }
             syn::Pat::Wild(_val) => {
                 let mut formatter = formatter.debug_struct("Pat::Wild");
                 if !_val.attrs.is_empty() {
                     formatter.field("attrs", Lite(&_val.attrs));
                 }
                 formatter.finish()
@@ -4669,19 +4669,19 @@ impl Debug for Lite<syn::TraitItem> {
                         }
                     }
                     formatter.field("semi_token", Print::ref_cast(val));
                 }
                 formatter.finish()
             }
             syn::TraitItem::Verbatim(_val) => {
                 formatter.write_str("Verbatim")?;
-                formatter.write_str("(")?;
-                Debug::fmt(Lite(_val), formatter)?;
-                formatter.write_str(")")?;
+                formatter.write_str("(`")?;
+                Display::fmt(_val, formatter)?;
+                formatter.write_str("`)")?;
                 Ok(())
             }
             _ => unreachable!(),
         }
     }
 }
 impl Debug for Lite<syn::TraitItemConst> {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
@@ -5035,19 +5035,19 @@ impl Debug for Lite<syn::Type> {
                 let mut formatter = formatter.debug_struct("Type::Tuple");
                 if !_val.elems.is_empty() {
                     formatter.field("elems", Lite(&_val.elems));
                 }
                 formatter.finish()
             }
             syn::Type::Verbatim(_val) => {
                 formatter.write_str("Verbatim")?;
-                formatter.write_str("(")?;
-                Debug::fmt(Lite(_val), formatter)?;
-                formatter.write_str(")")?;
+                formatter.write_str("(`")?;
+                Display::fmt(_val, formatter)?;
+                formatter.write_str("`)")?;
                 Ok(())
             }
             _ => unreachable!(),
         }
     }
 }
 impl Debug for Lite<syn::TypeArray> {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
diff --git a/third_party/rust/syn/tests/debug/mod.rs b/third_party/rust/syn/tests/debug/mod.rs
--- a/third_party/rust/syn/tests/debug/mod.rs
+++ b/third_party/rust/syn/tests/debug/mod.rs
@@ -1,15 +1,12 @@
-extern crate proc_macro2;
-extern crate ref_cast;
-
 mod gen;
 
-use self::proc_macro2::{Ident, Literal, TokenStream};
-use self::ref_cast::RefCast;
+use proc_macro2::{Ident, Literal, TokenStream};
+use ref_cast::RefCast;
 use std::fmt::{self, Debug};
 use std::ops::Deref;
 use syn::punctuated::Punctuated;
 
 #[derive(RefCast)]
 #[repr(transparent)]
 pub struct Lite<T: ?Sized> {
     value: T,
@@ -61,17 +58,25 @@ impl Debug for Lite<Ident> {
 impl Debug for Lite<Literal> {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         write!(formatter, "{}", self.value)
     }
 }
 
 impl Debug for Lite<TokenStream> {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-        write!(formatter, "`{}`", self.value)
+        let string = self.value.to_string();
+        if string.len() <= 80 {
+            write!(formatter, "TokenStream(`{}`)", self.value)
+        } else {
+            formatter
+                .debug_tuple("TokenStream")
+                .field(&format_args!("`{}`", string))
+                .finish()
+        }
     }
 }
 
 impl<'a, T> Debug for Lite<&'a T>
 where
     Lite<T>: Debug,
 {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
diff --git a/third_party/rust/syn/tests/features/error.rs b/third_party/rust/syn/tests/features/error.rs
deleted file mode 100644
--- a/third_party/rust/syn/tests/features/error.rs
+++ /dev/null
@@ -1,1 +0,0 @@
-"Hello! You want: cargo test --release --all-features"
diff --git a/third_party/rust/syn/tests/features/mod.rs b/third_party/rust/syn/tests/features/mod.rs
deleted file mode 100644
--- a/third_party/rust/syn/tests/features/mod.rs
+++ /dev/null
@@ -1,22 +0,0 @@
-#[allow(unused_macros)]
-macro_rules! hide_from_rustfmt {
-    ($mod:item) => {
-        $mod
-    };
-}
-
-#[cfg(not(all(
-    feature = "derive",
-    feature = "full",
-    feature = "parsing",
-    feature = "printing",
-    feature = "visit",
-    feature = "visit-mut",
-    feature = "fold",
-    feature = "clone-impls",
-    feature = "extra-traits",
-    feature = "proc-macro",
-)))]
-hide_from_rustfmt! {
-    mod error;
-}
diff --git a/third_party/rust/syn/tests/macros/mod.rs b/third_party/rust/syn/tests/macros/mod.rs
--- a/third_party/rust/syn/tests/macros/mod.rs
+++ b/third_party/rust/syn/tests/macros/mod.rs
@@ -1,10 +1,8 @@
-extern crate proc_macro2;
-
 #[path = "../debug/mod.rs"]
 pub mod debug;
 
 use syn;
 use syn::parse::{Parse, Result};
 
 #[macro_export]
 macro_rules! errorf {
@@ -37,28 +35,28 @@ macro_rules! snapshot {
     };
 }
 
 #[macro_export]
 macro_rules! snapshot_impl {
     (($expr:ident) as $t:ty, @$snapshot:literal) => {
         let $expr = crate::macros::Tokens::parse::<$t>($expr).unwrap();
         let debug = crate::macros::debug::Lite(&$expr);
-        insta::assert_debug_snapshot_matches!(debug, @$snapshot);
+        insta::assert_debug_snapshot!(debug, @$snapshot);
     };
     (($($expr:tt)*) as $t:ty, @$snapshot:literal) => {{
         let syntax_tree = crate::macros::Tokens::parse::<$t>($($expr)*).unwrap();
         let debug = crate::macros::debug::Lite(&syntax_tree);
-        insta::assert_debug_snapshot_matches!(debug, @$snapshot);
+        insta::assert_debug_snapshot!(debug, @$snapshot);
         syntax_tree
     }};
     (($($expr:tt)*) , @$snapshot:literal) => {{
         let syntax_tree = $($expr)*;
         let debug = crate::macros::debug::Lite(&syntax_tree);
-        insta::assert_debug_snapshot_matches!(debug, @$snapshot);
+        insta::assert_debug_snapshot!(debug, @$snapshot);
         syntax_tree
     }};
     (($($expr:tt)*) $next:tt $($rest:tt)*) => {
         snapshot_impl!(($($expr)* $next) $($rest)*)
     };
 }
 
 pub trait Tokens {
diff --git a/third_party/rust/syn/tests/repo/mod.rs b/third_party/rust/syn/tests/repo/mod.rs
--- a/third_party/rust/syn/tests/repo/mod.rs
+++ b/third_party/rust/syn/tests/repo/mod.rs
@@ -1,60 +1,135 @@
-extern crate walkdir;
+mod progress;
+
+use self::progress::Progress;
+use anyhow::Result;
+use flate2::read::GzDecoder;
+use std::fs;
+use std::path::Path;
+use tar::Archive;
+use walkdir::DirEntry;
+
+const REVISION: &str = "792c645ca7d11a8d254df307d019c5bf01445c37";
+
+#[rustfmt::skip]
+static EXCLUDE: &[&str] = &[
+    // Compile-fail expr parameter in const generic position: f::<1 + 2>()
+    "test/ui/const-generics/const-expression-parameter.rs",
 
-use std::process::Command;
+    // Deprecated anonymous parameter syntax in traits
+    "test/ui/issues/issue-13105.rs",
+    "test/ui/issues/issue-13775.rs",
+    "test/ui/issues/issue-34074.rs",
+    "test/ui/proc-macro/trait-fn-args-2015.rs",
 
-use self::walkdir::DirEntry;
+    // Not actually test cases
+    "test/rustdoc-ui/test-compile-fail2.rs",
+    "test/rustdoc-ui/test-compile-fail3.rs",
+    "test/ui/include-single-expr-helper.rs",
+    "test/ui/include-single-expr-helper-1.rs",
+    "test/ui/issues/auxiliary/issue-21146-inc.rs",
+    "test/ui/json-bom-plus-crlf-multifile-aux.rs",
+    "test/ui/lint/expansion-time-include.rs",
+    "test/ui/macros/auxiliary/macro-comma-support.rs",
+    "test/ui/macros/auxiliary/macro-include-items-expr.rs",
+];
 
 pub fn base_dir_filter(entry: &DirEntry) -> bool {
     let path = entry.path();
     if path.is_dir() {
         return true; // otherwise walkdir does not visit the files
     }
     if path.extension().map(|e| e != "rs").unwrap_or(true) {
         return false;
     }
-    let path_string = path.to_string_lossy();
-    let path_string = if cfg!(windows) {
-        path_string.replace('\\', "/").into()
+
+    let mut path_string = path.to_string_lossy();
+    if cfg!(windows) {
+        path_string = path_string.replace('\\', "/").into();
+    }
+    let path = if let Some(path) = path_string.strip_prefix("tests/rust/src/") {
+        path
+    } else if let Some(path) = path_string.strip_prefix("tests/rust/library/") {
+        path
     } else {
-        path_string
+        panic!("unexpected path in Rust dist: {}", path_string);
     };
+
     // TODO assert that parsing fails on the parse-fail cases
-    if path_string.starts_with("tests/rust/src/test/parse-fail")
-        || path_string.starts_with("tests/rust/src/test/compile-fail")
-        || path_string.starts_with("tests/rust/src/test/rustfix")
+    if path.starts_with("test/parse-fail")
+        || path.starts_with("test/compile-fail")
+        || path.starts_with("test/rustfix")
     {
         return false;
     }
 
-    if path_string.starts_with("tests/rust/src/test/ui") {
-        let stderr_path = path.with_extension("stderr");
+    if path.starts_with("test/ui") {
+        let stderr_path = entry.path().with_extension("stderr");
         if stderr_path.exists() {
             // Expected to fail in some way
             return false;
         }
     }
 
-    match path_string.as_ref() {
-        // Deprecated placement syntax
-        "tests/rust/src/test/ui/obsolete-in-place/bad.rs" |
-        // Deprecated anonymous parameter syntax in traits
-        "tests/rust/src/test/ui/error-codes/e0119/auxiliary/issue-23563-a.rs" |
-        "tests/rust/src/test/ui/issues/issue-13105.rs" |
-        "tests/rust/src/test/ui/issues/issue-13775.rs" |
-        "tests/rust/src/test/ui/issues/issue-34074.rs" |
-        // Deprecated await macro syntax
-        "tests/rust/src/test/ui/async-await/await-macro.rs" |
-        // 2015-style dyn that libsyntax rejects
-        "tests/rust/src/test/ui/dyn-keyword/dyn-2015-no-warnings-without-lints.rs" |
-        // not actually test cases
-        "tests/rust/src/test/ui/macros/auxiliary/macro-comma-support.rs" |
-        "tests/rust/src/test/ui/macros/auxiliary/macro-include-items-expr.rs" |
-        "tests/rust/src/test/ui/issues/auxiliary/issue-21146-inc.rs" => false,
-        _ => true,
+    !EXCLUDE.contains(&path)
+}
+
+#[allow(dead_code)]
+pub fn edition(path: &Path) -> &'static str {
+    if path.ends_with("dyn-2015-no-warnings-without-lints.rs") {
+        "2015"
+    } else {
+        "2018"
     }
 }
 
 pub fn clone_rust() {
-    let result = Command::new("tests/clone.sh").status().unwrap();
-    assert!(result.success());
+    let needs_clone = match fs::read_to_string("tests/rust/COMMIT") {
+        Err(_) => true,
+        Ok(contents) => contents.trim() != REVISION,
+    };
+    if needs_clone {
+        download_and_unpack().unwrap();
+    }
+    let mut missing = String::new();
+    let test_src = Path::new("tests/rust/src");
+    for exclude in EXCLUDE {
+        if !test_src.join(exclude).exists() {
+            missing += "\ntests/rust/src/";
+            missing += exclude;
+        }
+    }
+    if !missing.is_empty() {
+        panic!("excluded test file does not exist:{}\n", missing);
+    }
 }
+
+fn download_and_unpack() -> Result<()> {
+    let url = format!(
+        "https://github.com/rust-lang/rust/archive/{}.tar.gz",
+        REVISION
+    );
+    let response = reqwest::blocking::get(&url)?.error_for_status()?;
+    let progress = Progress::new(response);
+    let decoder = GzDecoder::new(progress);
+    let mut archive = Archive::new(decoder);
+    let prefix = format!("rust-{}", REVISION);
+
+    let tests_rust = Path::new("tests/rust");
+    if tests_rust.exists() {
+        fs::remove_dir_all(tests_rust)?;
+    }
+
+    for entry in archive.entries()? {
+        let mut entry = entry?;
+        let path = entry.path()?;
+        if path == Path::new("pax_global_header") {
+            continue;
+        }
+        let relative = path.strip_prefix(&prefix)?;
+        let out = tests_rust.join(relative);
+        entry.unpack(&out)?;
+    }
+
+    fs::write("tests/rust/COMMIT", REVISION)?;
+    Ok(())
+}
diff --git a/third_party/rust/syn/tests/repo/progress.rs b/third_party/rust/syn/tests/repo/progress.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/tests/repo/progress.rs
@@ -0,0 +1,37 @@
+use std::io::{Read, Result};
+use std::time::{Duration, Instant};
+
+pub struct Progress<R> {
+    bytes: usize,
+    tick: Instant,
+    stream: R,
+}
+
+impl<R> Progress<R> {
+    pub fn new(stream: R) -> Self {
+        Progress {
+            bytes: 0,
+            tick: Instant::now() + Duration::from_millis(2000),
+            stream,
+        }
+    }
+}
+
+impl<R: Read> Read for Progress<R> {
+    fn read(&mut self, buf: &mut [u8]) -> Result<usize> {
+        let num = self.stream.read(buf)?;
+        self.bytes += num;
+        let now = Instant::now();
+        if now > self.tick {
+            self.tick = now + Duration::from_millis(500);
+            errorf!("downloading... {} bytes\n", self.bytes);
+        }
+        Ok(num)
+    }
+}
+
+impl<R> Drop for Progress<R> {
+    fn drop(&mut self) {
+        errorf!("done ({} bytes)\n", self.bytes);
+    }
+}
diff --git a/third_party/rust/syn/tests/test_asyncness.rs b/third_party/rust/syn/tests/test_asyncness.rs
--- a/third_party/rust/syn/tests/test_asyncness.rs
+++ b/third_party/rust/syn/tests/test_asyncness.rs
@@ -1,41 +1,37 @@
-extern crate syn;
-
-mod features;
-
 #[macro_use]
 mod macros;
 
 use syn::{Expr, Item};
 
 #[test]
 fn test_async_fn() {
     let input = "async fn process() {}";
 
     snapshot!(input as Item, @r###"
-   ⋮Item::Fn {
-   ⋮    vis: Inherited,
-   ⋮    sig: Signature {
-   ⋮        asyncness: Some,
-   ⋮        ident: "process",
-   ⋮        generics: Generics,
-   ⋮        output: Default,
-   ⋮    },
-   ⋮    block: Block,
-   ⋮}
+    Item::Fn {
+        vis: Inherited,
+        sig: Signature {
+            asyncness: Some,
+            ident: "process",
+            generics: Generics,
+            output: Default,
+        },
+        block: Block,
+    }
     "###);
 }
 
 #[test]
 fn test_async_closure() {
     let input = "async || {}";
 
     snapshot!(input as Expr, @r###"
-   ⋮Expr::Closure {
-   ⋮    asyncness: Some,
-   ⋮    output: Default,
-   ⋮    body: Expr::Block {
-   ⋮        block: Block,
-   ⋮    },
-   ⋮}
+    Expr::Closure {
+        asyncness: Some,
+        output: Default,
+        body: Expr::Block {
+            block: Block,
+        },
+    }
     "###);
 }
diff --git a/third_party/rust/syn/tests/test_attribute.rs b/third_party/rust/syn/tests/test_attribute.rs
--- a/third_party/rust/syn/tests/test_attribute.rs
+++ b/third_party/rust/syn/tests/test_attribute.rs
@@ -1,295 +1,333 @@
-extern crate syn;
-
-mod features;
-
 #[macro_use]
 mod macros;
 
 use syn::parse::Parser;
 use syn::{Attribute, Meta};
 
 #[test]
 fn test_meta_item_word() {
     let meta = test("#[foo]");
 
     snapshot!(meta, @r###"
-   ⋮Path(Path {
-   ⋮    segments: [
-   ⋮        PathSegment {
-   ⋮            ident: "foo",
-   ⋮            arguments: None,
-   ⋮        },
-   ⋮    ],
-   ⋮})
+    Path(Path {
+        segments: [
+            PathSegment {
+                ident: "foo",
+                arguments: None,
+            },
+        ],
+    })
     "###);
 }
 
 #[test]
 fn test_meta_item_name_value() {
     let meta = test("#[foo = 5]");
 
     snapshot!(meta, @r###"
-   ⋮Meta::NameValue {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "foo",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    lit: 5,
-   ⋮}
+    Meta::NameValue {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "foo",
+                    arguments: None,
+                },
+            ],
+        },
+        lit: 5,
+    }
     "###);
 }
 
 #[test]
 fn test_meta_item_bool_value() {
     let meta = test("#[foo = true]");
 
     snapshot!(meta, @r###"
-   ⋮Meta::NameValue {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "foo",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    lit: Lit::Bool {
-   ⋮        value: true,
-   ⋮    },
-   ⋮}
+    Meta::NameValue {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "foo",
+                    arguments: None,
+                },
+            ],
+        },
+        lit: Lit::Bool {
+            value: true,
+        },
+    }
     "###);
 
     let meta = test("#[foo = false]");
 
     snapshot!(meta, @r###"
-   ⋮Meta::NameValue {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "foo",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    lit: Lit::Bool {
-   ⋮        value: false,
-   ⋮    },
-   ⋮}
+    Meta::NameValue {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "foo",
+                    arguments: None,
+                },
+            ],
+        },
+        lit: Lit::Bool {
+            value: false,
+        },
+    }
     "###);
 }
 
 #[test]
 fn test_meta_item_list_lit() {
     let meta = test("#[foo(5)]");
 
     snapshot!(meta, @r###"
-   ⋮Meta::List {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "foo",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    nested: [
-   ⋮        Lit(5),
-   ⋮    ],
-   ⋮}
+    Meta::List {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "foo",
+                    arguments: None,
+                },
+            ],
+        },
+        nested: [
+            Lit(5),
+        ],
+    }
     "###);
 }
 
 #[test]
 fn test_meta_item_list_word() {
     let meta = test("#[foo(bar)]");
 
     snapshot!(meta, @r###"
-   ⋮Meta::List {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "foo",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    nested: [
-   ⋮        Meta(Path(Path {
-   ⋮            segments: [
-   ⋮                PathSegment {
-   ⋮                    ident: "bar",
-   ⋮                    arguments: None,
-   ⋮                },
-   ⋮            ],
-   ⋮        })),
-   ⋮    ],
-   ⋮}
+    Meta::List {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "foo",
+                    arguments: None,
+                },
+            ],
+        },
+        nested: [
+            Meta(Path(Path {
+                segments: [
+                    PathSegment {
+                        ident: "bar",
+                        arguments: None,
+                    },
+                ],
+            })),
+        ],
+    }
     "###);
 }
 
 #[test]
 fn test_meta_item_list_name_value() {
     let meta = test("#[foo(bar = 5)]");
 
     snapshot!(meta, @r###"
-   ⋮Meta::List {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "foo",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    nested: [
-   ⋮        Meta(Meta::NameValue {
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "bar",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮            lit: 5,
-   ⋮        }),
-   ⋮    ],
-   ⋮}
+    Meta::List {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "foo",
+                    arguments: None,
+                },
+            ],
+        },
+        nested: [
+            Meta(Meta::NameValue {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "bar",
+                            arguments: None,
+                        },
+                    ],
+                },
+                lit: 5,
+            }),
+        ],
+    }
     "###);
 }
 
 #[test]
 fn test_meta_item_list_bool_value() {
     let meta = test("#[foo(bar = true)]");
 
     snapshot!(meta, @r###"
-   ⋮Meta::List {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "foo",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    nested: [
-   ⋮        Meta(Meta::NameValue {
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "bar",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮            lit: Lit::Bool {
-   ⋮                value: true,
-   ⋮            },
-   ⋮        }),
-   ⋮    ],
-   ⋮}
+    Meta::List {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "foo",
+                    arguments: None,
+                },
+            ],
+        },
+        nested: [
+            Meta(Meta::NameValue {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "bar",
+                            arguments: None,
+                        },
+                    ],
+                },
+                lit: Lit::Bool {
+                    value: true,
+                },
+            }),
+        ],
+    }
     "###);
 }
 
 #[test]
 fn test_meta_item_multiple() {
     let meta = test("#[foo(word, name = 5, list(name2 = 6), word2)]");
 
     snapshot!(meta, @r###"
-   ⋮Meta::List {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "foo",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    nested: [
-   ⋮        Meta(Path(Path {
-   ⋮            segments: [
-   ⋮                PathSegment {
-   ⋮                    ident: "word",
-   ⋮                    arguments: None,
-   ⋮                },
-   ⋮            ],
-   ⋮        })),
-   ⋮        Meta(Meta::NameValue {
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "name",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮            lit: 5,
-   ⋮        }),
-   ⋮        Meta(Meta::List {
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "list",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮            nested: [
-   ⋮                Meta(Meta::NameValue {
-   ⋮                    path: Path {
-   ⋮                        segments: [
-   ⋮                            PathSegment {
-   ⋮                                ident: "name2",
-   ⋮                                arguments: None,
-   ⋮                            },
-   ⋮                        ],
-   ⋮                    },
-   ⋮                    lit: 6,
-   ⋮                }),
-   ⋮            ],
-   ⋮        }),
-   ⋮        Meta(Path(Path {
-   ⋮            segments: [
-   ⋮                PathSegment {
-   ⋮                    ident: "word2",
-   ⋮                    arguments: None,
-   ⋮                },
-   ⋮            ],
-   ⋮        })),
-   ⋮    ],
-   ⋮}
+    Meta::List {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "foo",
+                    arguments: None,
+                },
+            ],
+        },
+        nested: [
+            Meta(Path(Path {
+                segments: [
+                    PathSegment {
+                        ident: "word",
+                        arguments: None,
+                    },
+                ],
+            })),
+            Meta(Meta::NameValue {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "name",
+                            arguments: None,
+                        },
+                    ],
+                },
+                lit: 5,
+            }),
+            Meta(Meta::List {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "list",
+                            arguments: None,
+                        },
+                    ],
+                },
+                nested: [
+                    Meta(Meta::NameValue {
+                        path: Path {
+                            segments: [
+                                PathSegment {
+                                    ident: "name2",
+                                    arguments: None,
+                                },
+                            ],
+                        },
+                        lit: 6,
+                    }),
+                ],
+            }),
+            Meta(Path(Path {
+                segments: [
+                    PathSegment {
+                        ident: "word2",
+                        arguments: None,
+                    },
+                ],
+            })),
+        ],
+    }
     "###);
 }
 
 #[test]
 fn test_bool_lit() {
     let meta = test("#[foo(true)]");
 
     snapshot!(meta, @r###"
-   ⋮Meta::List {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "foo",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    nested: [
-   ⋮        Lit(Lit::Bool {
-   ⋮            value: true,
-   ⋮        }),
-   ⋮    ],
-   ⋮}
+    Meta::List {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "foo",
+                    arguments: None,
+                },
+            ],
+        },
+        nested: [
+            Lit(Lit::Bool {
+                value: true,
+            }),
+        ],
+    }
+    "###);
+}
+
+#[test]
+fn test_negative_lit() {
+    let meta = test("#[form(min = -1, max = 200)]");
+
+    snapshot!(meta, @r###"
+    Meta::List {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "form",
+                    arguments: None,
+                },
+            ],
+        },
+        nested: [
+            Meta(Meta::NameValue {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "min",
+                            arguments: None,
+                        },
+                    ],
+                },
+                lit: -1,
+            }),
+            Meta(Meta::NameValue {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "max",
+                            arguments: None,
+                        },
+                    ],
+                },
+                lit: 200,
+            }),
+        ],
+    }
     "###);
 }
 
 fn test(input: &str) -> Meta {
     let attrs = Attribute::parse_outer.parse_str(input).unwrap();
 
     assert_eq!(attrs.len(), 1);
     let attr = attrs.into_iter().next().unwrap();
diff --git a/third_party/rust/syn/tests/test_derive_input.rs b/third_party/rust/syn/tests/test_derive_input.rs
--- a/third_party/rust/syn/tests/test_derive_input.rs
+++ b/third_party/rust/syn/tests/test_derive_input.rs
@@ -1,201 +1,196 @@
-extern crate quote;
-extern crate syn;
-
-mod features;
-
 #[macro_use]
 mod macros;
 
 use quote::quote;
 use syn::{Data, DeriveInput};
 
 #[test]
 fn test_unit() {
     let input = quote! {
         struct Unit;
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    vis: Inherited,
-   ⋮    ident: "Unit",
-   ⋮    generics: Generics,
-   ⋮    data: Data::Struct {
-   ⋮        fields: Unit,
-   ⋮        semi_token: Some,
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        vis: Inherited,
+        ident: "Unit",
+        generics: Generics,
+        data: Data::Struct {
+            fields: Unit,
+            semi_token: Some,
+        },
+    }
     "###);
 }
 
 #[test]
 fn test_struct() {
     let input = quote! {
         #[derive(Debug, Clone)]
         pub struct Item {
             pub ident: Ident,
             pub attrs: Vec<Attribute>
         }
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    attrs: [
-   ⋮        Attribute {
-   ⋮            style: Outer,
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "derive",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮            tokens: `( Debug , Clone )`,
-   ⋮        },
-   ⋮    ],
-   ⋮    vis: Visibility::Public,
-   ⋮    ident: "Item",
-   ⋮    generics: Generics,
-   ⋮    data: Data::Struct {
-   ⋮        fields: Fields::Named {
-   ⋮            named: [
-   ⋮                Field {
-   ⋮                    vis: Visibility::Public,
-   ⋮                    ident: Some("ident"),
-   ⋮                    colon_token: Some,
-   ⋮                    ty: Type::Path {
-   ⋮                        path: Path {
-   ⋮                            segments: [
-   ⋮                                PathSegment {
-   ⋮                                    ident: "Ident",
-   ⋮                                    arguments: None,
-   ⋮                                },
-   ⋮                            ],
-   ⋮                        },
-   ⋮                    },
-   ⋮                },
-   ⋮                Field {
-   ⋮                    vis: Visibility::Public,
-   ⋮                    ident: Some("attrs"),
-   ⋮                    colon_token: Some,
-   ⋮                    ty: Type::Path {
-   ⋮                        path: Path {
-   ⋮                            segments: [
-   ⋮                                PathSegment {
-   ⋮                                    ident: "Vec",
-   ⋮                                    arguments: PathArguments::AngleBracketed {
-   ⋮                                        args: [
-   ⋮                                            Type(Type::Path {
-   ⋮                                                path: Path {
-   ⋮                                                    segments: [
-   ⋮                                                        PathSegment {
-   ⋮                                                            ident: "Attribute",
-   ⋮                                                            arguments: None,
-   ⋮                                                        },
-   ⋮                                                    ],
-   ⋮                                                },
-   ⋮                                            }),
-   ⋮                                        ],
-   ⋮                                    },
-   ⋮                                },
-   ⋮                            ],
-   ⋮                        },
-   ⋮                    },
-   ⋮                },
-   ⋮            ],
-   ⋮        },
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        attrs: [
+            Attribute {
+                style: Outer,
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "derive",
+                            arguments: None,
+                        },
+                    ],
+                },
+                tokens: TokenStream(`(Debug , Clone)`),
+            },
+        ],
+        vis: Visibility::Public,
+        ident: "Item",
+        generics: Generics,
+        data: Data::Struct {
+            fields: Fields::Named {
+                named: [
+                    Field {
+                        vis: Visibility::Public,
+                        ident: Some("ident"),
+                        colon_token: Some,
+                        ty: Type::Path {
+                            path: Path {
+                                segments: [
+                                    PathSegment {
+                                        ident: "Ident",
+                                        arguments: None,
+                                    },
+                                ],
+                            },
+                        },
+                    },
+                    Field {
+                        vis: Visibility::Public,
+                        ident: Some("attrs"),
+                        colon_token: Some,
+                        ty: Type::Path {
+                            path: Path {
+                                segments: [
+                                    PathSegment {
+                                        ident: "Vec",
+                                        arguments: PathArguments::AngleBracketed {
+                                            args: [
+                                                Type(Type::Path {
+                                                    path: Path {
+                                                        segments: [
+                                                            PathSegment {
+                                                                ident: "Attribute",
+                                                                arguments: None,
+                                                            },
+                                                        ],
+                                                    },
+                                                }),
+                                            ],
+                                        },
+                                    },
+                                ],
+                            },
+                        },
+                    },
+                ],
+            },
+        },
+    }
     "###);
 
     snapshot!(input.attrs[0].parse_meta().unwrap(), @r###"
-   ⋮Meta::List {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "derive",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    nested: [
-   ⋮        Meta(Path(Path {
-   ⋮            segments: [
-   ⋮                PathSegment {
-   ⋮                    ident: "Debug",
-   ⋮                    arguments: None,
-   ⋮                },
-   ⋮            ],
-   ⋮        })),
-   ⋮        Meta(Path(Path {
-   ⋮            segments: [
-   ⋮                PathSegment {
-   ⋮                    ident: "Clone",
-   ⋮                    arguments: None,
-   ⋮                },
-   ⋮            ],
-   ⋮        })),
-   ⋮    ],
-   ⋮}
+    Meta::List {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "derive",
+                    arguments: None,
+                },
+            ],
+        },
+        nested: [
+            Meta(Path(Path {
+                segments: [
+                    PathSegment {
+                        ident: "Debug",
+                        arguments: None,
+                    },
+                ],
+            })),
+            Meta(Path(Path {
+                segments: [
+                    PathSegment {
+                        ident: "Clone",
+                        arguments: None,
+                    },
+                ],
+            })),
+        ],
+    }
     "###);
 }
 
 #[test]
 fn test_union() {
     let input = quote! {
         union MaybeUninit<T> {
             uninit: (),
             value: T
         }
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    vis: Inherited,
-   ⋮    ident: "MaybeUninit",
-   ⋮    generics: Generics {
-   ⋮        lt_token: Some,
-   ⋮        params: [
-   ⋮            Type(TypeParam {
-   ⋮                ident: "T",
-   ⋮            }),
-   ⋮        ],
-   ⋮        gt_token: Some,
-   ⋮    },
-   ⋮    data: Data::Union {
-   ⋮        fields: FieldsNamed {
-   ⋮            named: [
-   ⋮                Field {
-   ⋮                    vis: Inherited,
-   ⋮                    ident: Some("uninit"),
-   ⋮                    colon_token: Some,
-   ⋮                    ty: Type::Tuple,
-   ⋮                },
-   ⋮                Field {
-   ⋮                    vis: Inherited,
-   ⋮                    ident: Some("value"),
-   ⋮                    colon_token: Some,
-   ⋮                    ty: Type::Path {
-   ⋮                        path: Path {
-   ⋮                            segments: [
-   ⋮                                PathSegment {
-   ⋮                                    ident: "T",
-   ⋮                                    arguments: None,
-   ⋮                                },
-   ⋮                            ],
-   ⋮                        },
-   ⋮                    },
-   ⋮                },
-   ⋮            ],
-   ⋮        },
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        vis: Inherited,
+        ident: "MaybeUninit",
+        generics: Generics {
+            lt_token: Some,
+            params: [
+                Type(TypeParam {
+                    ident: "T",
+                }),
+            ],
+            gt_token: Some,
+        },
+        data: Data::Union {
+            fields: FieldsNamed {
+                named: [
+                    Field {
+                        vis: Inherited,
+                        ident: Some("uninit"),
+                        colon_token: Some,
+                        ty: Type::Tuple,
+                    },
+                    Field {
+                        vis: Inherited,
+                        ident: Some("value"),
+                        colon_token: Some,
+                        ty: Type::Path {
+                            path: Path {
+                                segments: [
+                                    PathSegment {
+                                        ident: "T",
+                                        arguments: None,
+                                    },
+                                ],
+                            },
+                        },
+                    },
+                ],
+            },
+        },
+    }
     "###);
 }
 
 #[test]
 #[cfg(feature = "full")]
 fn test_enum() {
     let input = quote! {
         /// See the std::result module documentation for details.
@@ -207,472 +202,472 @@ fn test_enum() {
 
             // Smuggling data into a proc_macro_derive,
             // in the style of https://github.com/dtolnay/proc-macro-hack
             ProcMacroHack = (0, "data").0
         }
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    attrs: [
-   ⋮        Attribute {
-   ⋮            style: Outer,
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "doc",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮            tokens: `= r" See the std::result module documentation for details."`,
-   ⋮        },
-   ⋮        Attribute {
-   ⋮            style: Outer,
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "must_use",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮            tokens: ``,
-   ⋮        },
-   ⋮    ],
-   ⋮    vis: Visibility::Public,
-   ⋮    ident: "Result",
-   ⋮    generics: Generics {
-   ⋮        lt_token: Some,
-   ⋮        params: [
-   ⋮            Type(TypeParam {
-   ⋮                ident: "T",
-   ⋮            }),
-   ⋮            Type(TypeParam {
-   ⋮                ident: "E",
-   ⋮            }),
-   ⋮        ],
-   ⋮        gt_token: Some,
-   ⋮    },
-   ⋮    data: Data::Enum {
-   ⋮        variants: [
-   ⋮            Variant {
-   ⋮                ident: "Ok",
-   ⋮                fields: Fields::Unnamed {
-   ⋮                    unnamed: [
-   ⋮                        Field {
-   ⋮                            vis: Inherited,
-   ⋮                            ty: Type::Path {
-   ⋮                                path: Path {
-   ⋮                                    segments: [
-   ⋮                                        PathSegment {
-   ⋮                                            ident: "T",
-   ⋮                                            arguments: None,
-   ⋮                                        },
-   ⋮                                    ],
-   ⋮                                },
-   ⋮                            },
-   ⋮                        },
-   ⋮                    ],
-   ⋮                },
-   ⋮            },
-   ⋮            Variant {
-   ⋮                ident: "Err",
-   ⋮                fields: Fields::Unnamed {
-   ⋮                    unnamed: [
-   ⋮                        Field {
-   ⋮                            vis: Inherited,
-   ⋮                            ty: Type::Path {
-   ⋮                                path: Path {
-   ⋮                                    segments: [
-   ⋮                                        PathSegment {
-   ⋮                                            ident: "E",
-   ⋮                                            arguments: None,
-   ⋮                                        },
-   ⋮                                    ],
-   ⋮                                },
-   ⋮                            },
-   ⋮                        },
-   ⋮                    ],
-   ⋮                },
-   ⋮            },
-   ⋮            Variant {
-   ⋮                ident: "Surprise",
-   ⋮                fields: Unit,
-   ⋮                discriminant: Some(Expr::Lit {
-   ⋮                    lit: 0isize,
-   ⋮                }),
-   ⋮            },
-   ⋮            Variant {
-   ⋮                ident: "ProcMacroHack",
-   ⋮                fields: Unit,
-   ⋮                discriminant: Some(Expr::Field {
-   ⋮                    base: Expr::Tuple {
-   ⋮                        elems: [
-   ⋮                            Expr::Lit {
-   ⋮                                lit: 0,
-   ⋮                            },
-   ⋮                            Expr::Lit {
-   ⋮                                lit: "data",
-   ⋮                            },
-   ⋮                        ],
-   ⋮                    },
-   ⋮                    member: Unnamed(Index {
-   ⋮                        index: 0,
-   ⋮                    }),
-   ⋮                }),
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        attrs: [
+            Attribute {
+                style: Outer,
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "doc",
+                            arguments: None,
+                        },
+                    ],
+                },
+                tokens: TokenStream(`= r" See the std::result module documentation for details."`),
+            },
+            Attribute {
+                style: Outer,
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "must_use",
+                            arguments: None,
+                        },
+                    ],
+                },
+                tokens: TokenStream(``),
+            },
+        ],
+        vis: Visibility::Public,
+        ident: "Result",
+        generics: Generics {
+            lt_token: Some,
+            params: [
+                Type(TypeParam {
+                    ident: "T",
+                }),
+                Type(TypeParam {
+                    ident: "E",
+                }),
+            ],
+            gt_token: Some,
+        },
+        data: Data::Enum {
+            variants: [
+                Variant {
+                    ident: "Ok",
+                    fields: Fields::Unnamed {
+                        unnamed: [
+                            Field {
+                                vis: Inherited,
+                                ty: Type::Path {
+                                    path: Path {
+                                        segments: [
+                                            PathSegment {
+                                                ident: "T",
+                                                arguments: None,
+                                            },
+                                        ],
+                                    },
+                                },
+                            },
+                        ],
+                    },
+                },
+                Variant {
+                    ident: "Err",
+                    fields: Fields::Unnamed {
+                        unnamed: [
+                            Field {
+                                vis: Inherited,
+                                ty: Type::Path {
+                                    path: Path {
+                                        segments: [
+                                            PathSegment {
+                                                ident: "E",
+                                                arguments: None,
+                                            },
+                                        ],
+                                    },
+                                },
+                            },
+                        ],
+                    },
+                },
+                Variant {
+                    ident: "Surprise",
+                    fields: Unit,
+                    discriminant: Some(Expr::Lit {
+                        lit: 0isize,
+                    }),
+                },
+                Variant {
+                    ident: "ProcMacroHack",
+                    fields: Unit,
+                    discriminant: Some(Expr::Field {
+                        base: Expr::Tuple {
+                            elems: [
+                                Expr::Lit {
+                                    lit: 0,
+                                },
+                                Expr::Lit {
+                                    lit: "data",
+                                },
+                            ],
+                        },
+                        member: Unnamed(Index {
+                            index: 0,
+                        }),
+                    }),
+                },
+            ],
+        },
+    }
     "###);
 
     let meta_items: Vec<_> = input
         .attrs
         .into_iter()
         .map(|attr| attr.parse_meta().unwrap())
         .collect();
 
     snapshot!(meta_items, @r###"
-   ⋮[
-   ⋮    Meta::NameValue {
-   ⋮        path: Path {
-   ⋮            segments: [
-   ⋮                PathSegment {
-   ⋮                    ident: "doc",
-   ⋮                    arguments: None,
-   ⋮                },
-   ⋮            ],
-   ⋮        },
-   ⋮        lit: " See the std::result module documentation for details.",
-   ⋮    },
-   ⋮    Path(Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "must_use",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    }),
-   ⋮]
+    [
+        Meta::NameValue {
+            path: Path {
+                segments: [
+                    PathSegment {
+                        ident: "doc",
+                        arguments: None,
+                    },
+                ],
+            },
+            lit: " See the std::result module documentation for details.",
+        },
+        Path(Path {
+            segments: [
+                PathSegment {
+                    ident: "must_use",
+                    arguments: None,
+                },
+            ],
+        }),
+    ]
     "###);
 }
 
 #[test]
 fn test_attr_with_path() {
     let input = quote! {
         #[::attr_args::identity
             fn main() { assert_eq!(foo(), "Hello, world!"); }]
         struct Dummy;
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    attrs: [
-   ⋮        Attribute {
-   ⋮            style: Outer,
-   ⋮            path: Path {
-   ⋮                leading_colon: Some,
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "attr_args",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                    PathSegment {
-   ⋮                        ident: "identity",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮            tokens: `fn main ( ) { assert_eq ! ( foo ( ) , "Hello, world!" ) ; }`,
-   ⋮        },
-   ⋮    ],
-   ⋮    vis: Inherited,
-   ⋮    ident: "Dummy",
-   ⋮    generics: Generics,
-   ⋮    data: Data::Struct {
-   ⋮        fields: Unit,
-   ⋮        semi_token: Some,
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        attrs: [
+            Attribute {
+                style: Outer,
+                path: Path {
+                    leading_colon: Some,
+                    segments: [
+                        PathSegment {
+                            ident: "attr_args",
+                            arguments: None,
+                        },
+                        PathSegment {
+                            ident: "identity",
+                            arguments: None,
+                        },
+                    ],
+                },
+                tokens: TokenStream(`fn main () { assert_eq ! (foo () , "Hello, world!") ; }`),
+            },
+        ],
+        vis: Inherited,
+        ident: "Dummy",
+        generics: Generics,
+        data: Data::Struct {
+            fields: Unit,
+            semi_token: Some,
+        },
+    }
     "###);
 
     assert!(input.attrs[0].parse_meta().is_err());
 }
 
 #[test]
 fn test_attr_with_non_mod_style_path() {
     let input = quote! {
         #[inert <T>]
         struct S;
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    attrs: [
-   ⋮        Attribute {
-   ⋮            style: Outer,
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "inert",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮            tokens: `< T >`,
-   ⋮        },
-   ⋮    ],
-   ⋮    vis: Inherited,
-   ⋮    ident: "S",
-   ⋮    generics: Generics,
-   ⋮    data: Data::Struct {
-   ⋮        fields: Unit,
-   ⋮        semi_token: Some,
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        attrs: [
+            Attribute {
+                style: Outer,
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "inert",
+                            arguments: None,
+                        },
+                    ],
+                },
+                tokens: TokenStream(`< T >`),
+            },
+        ],
+        vis: Inherited,
+        ident: "S",
+        generics: Generics,
+        data: Data::Struct {
+            fields: Unit,
+            semi_token: Some,
+        },
+    }
     "###);
 
     assert!(input.attrs[0].parse_meta().is_err());
 }
 
 #[test]
 fn test_attr_with_mod_style_path_with_self() {
     let input = quote! {
         #[foo::self]
         struct S;
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    attrs: [
-   ⋮        Attribute {
-   ⋮            style: Outer,
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "foo",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                    PathSegment {
-   ⋮                        ident: "self",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮            tokens: ``,
-   ⋮        },
-   ⋮    ],
-   ⋮    vis: Inherited,
-   ⋮    ident: "S",
-   ⋮    generics: Generics,
-   ⋮    data: Data::Struct {
-   ⋮        fields: Unit,
-   ⋮        semi_token: Some,
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        attrs: [
+            Attribute {
+                style: Outer,
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "foo",
+                            arguments: None,
+                        },
+                        PathSegment {
+                            ident: "self",
+                            arguments: None,
+                        },
+                    ],
+                },
+                tokens: TokenStream(``),
+            },
+        ],
+        vis: Inherited,
+        ident: "S",
+        generics: Generics,
+        data: Data::Struct {
+            fields: Unit,
+            semi_token: Some,
+        },
+    }
     "###);
 
     snapshot!(input.attrs[0].parse_meta().unwrap(), @r###"
-   ⋮Path(Path {
-   ⋮    segments: [
-   ⋮        PathSegment {
-   ⋮            ident: "foo",
-   ⋮            arguments: None,
-   ⋮        },
-   ⋮        PathSegment {
-   ⋮            ident: "self",
-   ⋮            arguments: None,
-   ⋮        },
-   ⋮    ],
-   ⋮})
+    Path(Path {
+        segments: [
+            PathSegment {
+                ident: "foo",
+                arguments: None,
+            },
+            PathSegment {
+                ident: "self",
+                arguments: None,
+            },
+        ],
+    })
     "###);
 }
 
 #[test]
 fn test_pub_restricted() {
     // Taken from tests/rust/src/test/ui/resolve/auxiliary/privacy-struct-ctor.rs
     let input = quote! {
         pub(in m) struct Z(pub(in m::n) u8);
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    vis: Visibility::Restricted {
-   ⋮        in_token: Some,
-   ⋮        path: Path {
-   ⋮            segments: [
-   ⋮                PathSegment {
-   ⋮                    ident: "m",
-   ⋮                    arguments: None,
-   ⋮                },
-   ⋮            ],
-   ⋮        },
-   ⋮    },
-   ⋮    ident: "Z",
-   ⋮    generics: Generics,
-   ⋮    data: Data::Struct {
-   ⋮        fields: Fields::Unnamed {
-   ⋮            unnamed: [
-   ⋮                Field {
-   ⋮                    vis: Visibility::Restricted {
-   ⋮                        in_token: Some,
-   ⋮                        path: Path {
-   ⋮                            segments: [
-   ⋮                                PathSegment {
-   ⋮                                    ident: "m",
-   ⋮                                    arguments: None,
-   ⋮                                },
-   ⋮                                PathSegment {
-   ⋮                                    ident: "n",
-   ⋮                                    arguments: None,
-   ⋮                                },
-   ⋮                            ],
-   ⋮                        },
-   ⋮                    },
-   ⋮                    ty: Type::Path {
-   ⋮                        path: Path {
-   ⋮                            segments: [
-   ⋮                                PathSegment {
-   ⋮                                    ident: "u8",
-   ⋮                                    arguments: None,
-   ⋮                                },
-   ⋮                            ],
-   ⋮                        },
-   ⋮                    },
-   ⋮                },
-   ⋮            ],
-   ⋮        },
-   ⋮        semi_token: Some,
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        vis: Visibility::Restricted {
+            in_token: Some,
+            path: Path {
+                segments: [
+                    PathSegment {
+                        ident: "m",
+                        arguments: None,
+                    },
+                ],
+            },
+        },
+        ident: "Z",
+        generics: Generics,
+        data: Data::Struct {
+            fields: Fields::Unnamed {
+                unnamed: [
+                    Field {
+                        vis: Visibility::Restricted {
+                            in_token: Some,
+                            path: Path {
+                                segments: [
+                                    PathSegment {
+                                        ident: "m",
+                                        arguments: None,
+                                    },
+                                    PathSegment {
+                                        ident: "n",
+                                        arguments: None,
+                                    },
+                                ],
+                            },
+                        },
+                        ty: Type::Path {
+                            path: Path {
+                                segments: [
+                                    PathSegment {
+                                        ident: "u8",
+                                        arguments: None,
+                                    },
+                                ],
+                            },
+                        },
+                    },
+                ],
+            },
+            semi_token: Some,
+        },
+    }
     "###);
 }
 
 #[test]
 fn test_vis_crate() {
     let input = quote! {
         crate struct S;
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    vis: Visibility::Crate,
-   ⋮    ident: "S",
-   ⋮    generics: Generics,
-   ⋮    data: Data::Struct {
-   ⋮        fields: Unit,
-   ⋮        semi_token: Some,
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        vis: Visibility::Crate,
+        ident: "S",
+        generics: Generics,
+        data: Data::Struct {
+            fields: Unit,
+            semi_token: Some,
+        },
+    }
     "###);
 }
 
 #[test]
 fn test_pub_restricted_crate() {
     let input = quote! {
         pub(crate) struct S;
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    vis: Visibility::Restricted {
-   ⋮        path: Path {
-   ⋮            segments: [
-   ⋮                PathSegment {
-   ⋮                    ident: "crate",
-   ⋮                    arguments: None,
-   ⋮                },
-   ⋮            ],
-   ⋮        },
-   ⋮    },
-   ⋮    ident: "S",
-   ⋮    generics: Generics,
-   ⋮    data: Data::Struct {
-   ⋮        fields: Unit,
-   ⋮        semi_token: Some,
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        vis: Visibility::Restricted {
+            path: Path {
+                segments: [
+                    PathSegment {
+                        ident: "crate",
+                        arguments: None,
+                    },
+                ],
+            },
+        },
+        ident: "S",
+        generics: Generics,
+        data: Data::Struct {
+            fields: Unit,
+            semi_token: Some,
+        },
+    }
     "###);
 }
 
 #[test]
 fn test_pub_restricted_super() {
     let input = quote! {
         pub(super) struct S;
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    vis: Visibility::Restricted {
-   ⋮        path: Path {
-   ⋮            segments: [
-   ⋮                PathSegment {
-   ⋮                    ident: "super",
-   ⋮                    arguments: None,
-   ⋮                },
-   ⋮            ],
-   ⋮        },
-   ⋮    },
-   ⋮    ident: "S",
-   ⋮    generics: Generics,
-   ⋮    data: Data::Struct {
-   ⋮        fields: Unit,
-   ⋮        semi_token: Some,
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        vis: Visibility::Restricted {
+            path: Path {
+                segments: [
+                    PathSegment {
+                        ident: "super",
+                        arguments: None,
+                    },
+                ],
+            },
+        },
+        ident: "S",
+        generics: Generics,
+        data: Data::Struct {
+            fields: Unit,
+            semi_token: Some,
+        },
+    }
     "###);
 }
 
 #[test]
 fn test_pub_restricted_in_super() {
     let input = quote! {
         pub(in super) struct S;
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    vis: Visibility::Restricted {
-   ⋮        in_token: Some,
-   ⋮        path: Path {
-   ⋮            segments: [
-   ⋮                PathSegment {
-   ⋮                    ident: "super",
-   ⋮                    arguments: None,
-   ⋮                },
-   ⋮            ],
-   ⋮        },
-   ⋮    },
-   ⋮    ident: "S",
-   ⋮    generics: Generics,
-   ⋮    data: Data::Struct {
-   ⋮        fields: Unit,
-   ⋮        semi_token: Some,
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        vis: Visibility::Restricted {
+            in_token: Some,
+            path: Path {
+                segments: [
+                    PathSegment {
+                        ident: "super",
+                        arguments: None,
+                    },
+                ],
+            },
+        },
+        ident: "S",
+        generics: Generics,
+        data: Data::Struct {
+            fields: Unit,
+            semi_token: Some,
+        },
+    }
     "###);
 }
 
 #[test]
 fn test_fields_on_unit_struct() {
     let input = quote! {
         struct S;
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    vis: Inherited,
-   ⋮    ident: "S",
-   ⋮    generics: Generics,
-   ⋮    data: Data::Struct {
-   ⋮        fields: Unit,
-   ⋮        semi_token: Some,
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        vis: Inherited,
+        ident: "S",
+        generics: Generics,
+        data: Data::Struct {
+            fields: Unit,
+            semi_token: Some,
+        },
+    }
     "###);
 
     let data = match input.data {
         Data::Struct(data) => data,
         _ => panic!("expected a struct"),
     };
 
     assert_eq!(0, data.fields.iter().count());
@@ -683,215 +678,215 @@ fn test_fields_on_named_struct() {
     let input = quote! {
         struct S {
             foo: i32,
             pub bar: String,
         }
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    vis: Inherited,
-   ⋮    ident: "S",
-   ⋮    generics: Generics,
-   ⋮    data: Data::Struct {
-   ⋮        fields: Fields::Named {
-   ⋮            named: [
-   ⋮                Field {
-   ⋮                    vis: Inherited,
-   ⋮                    ident: Some("foo"),
-   ⋮                    colon_token: Some,
-   ⋮                    ty: Type::Path {
-   ⋮                        path: Path {
-   ⋮                            segments: [
-   ⋮                                PathSegment {
-   ⋮                                    ident: "i32",
-   ⋮                                    arguments: None,
-   ⋮                                },
-   ⋮                            ],
-   ⋮                        },
-   ⋮                    },
-   ⋮                },
-   ⋮                Field {
-   ⋮                    vis: Visibility::Public,
-   ⋮                    ident: Some("bar"),
-   ⋮                    colon_token: Some,
-   ⋮                    ty: Type::Path {
-   ⋮                        path: Path {
-   ⋮                            segments: [
-   ⋮                                PathSegment {
-   ⋮                                    ident: "String",
-   ⋮                                    arguments: None,
-   ⋮                                },
-   ⋮                            ],
-   ⋮                        },
-   ⋮                    },
-   ⋮                },
-   ⋮            ],
-   ⋮        },
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        vis: Inherited,
+        ident: "S",
+        generics: Generics,
+        data: Data::Struct {
+            fields: Fields::Named {
+                named: [
+                    Field {
+                        vis: Inherited,
+                        ident: Some("foo"),
+                        colon_token: Some,
+                        ty: Type::Path {
+                            path: Path {
+                                segments: [
+                                    PathSegment {
+                                        ident: "i32",
+                                        arguments: None,
+                                    },
+                                ],
+                            },
+                        },
+                    },
+                    Field {
+                        vis: Visibility::Public,
+                        ident: Some("bar"),
+                        colon_token: Some,
+                        ty: Type::Path {
+                            path: Path {
+                                segments: [
+                                    PathSegment {
+                                        ident: "String",
+                                        arguments: None,
+                                    },
+                                ],
+                            },
+                        },
+                    },
+                ],
+            },
+        },
+    }
     "###);
 
     let data = match input.data {
         Data::Struct(data) => data,
         _ => panic!("expected a struct"),
     };
 
     snapshot!(data.fields.into_iter().collect::<Vec<_>>(), @r###"
-   ⋮[
-   ⋮    Field {
-   ⋮        vis: Inherited,
-   ⋮        ident: Some("foo"),
-   ⋮        colon_token: Some,
-   ⋮        ty: Type::Path {
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "i32",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮        },
-   ⋮    },
-   ⋮    Field {
-   ⋮        vis: Visibility::Public,
-   ⋮        ident: Some("bar"),
-   ⋮        colon_token: Some,
-   ⋮        ty: Type::Path {
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "String",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮        },
-   ⋮    },
-   ⋮]
+    [
+        Field {
+            vis: Inherited,
+            ident: Some("foo"),
+            colon_token: Some,
+            ty: Type::Path {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "i32",
+                            arguments: None,
+                        },
+                    ],
+                },
+            },
+        },
+        Field {
+            vis: Visibility::Public,
+            ident: Some("bar"),
+            colon_token: Some,
+            ty: Type::Path {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "String",
+                            arguments: None,
+                        },
+                    ],
+                },
+            },
+        },
+    ]
     "###);
 }
 
 #[test]
 fn test_fields_on_tuple_struct() {
     let input = quote! {
         struct S(i32, pub String);
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    vis: Inherited,
-   ⋮    ident: "S",
-   ⋮    generics: Generics,
-   ⋮    data: Data::Struct {
-   ⋮        fields: Fields::Unnamed {
-   ⋮            unnamed: [
-   ⋮                Field {
-   ⋮                    vis: Inherited,
-   ⋮                    ty: Type::Path {
-   ⋮                        path: Path {
-   ⋮                            segments: [
-   ⋮                                PathSegment {
-   ⋮                                    ident: "i32",
-   ⋮                                    arguments: None,
-   ⋮                                },
-   ⋮                            ],
-   ⋮                        },
-   ⋮                    },
-   ⋮                },
-   ⋮                Field {
-   ⋮                    vis: Visibility::Public,
-   ⋮                    ty: Type::Path {
-   ⋮                        path: Path {
-   ⋮                            segments: [
-   ⋮                                PathSegment {
-   ⋮                                    ident: "String",
-   ⋮                                    arguments: None,
-   ⋮                                },
-   ⋮                            ],
-   ⋮                        },
-   ⋮                    },
-   ⋮                },
-   ⋮            ],
-   ⋮        },
-   ⋮        semi_token: Some,
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        vis: Inherited,
+        ident: "S",
+        generics: Generics,
+        data: Data::Struct {
+            fields: Fields::Unnamed {
+                unnamed: [
+                    Field {
+                        vis: Inherited,
+                        ty: Type::Path {
+                            path: Path {
+                                segments: [
+                                    PathSegment {
+                                        ident: "i32",
+                                        arguments: None,
+                                    },
+                                ],
+                            },
+                        },
+                    },
+                    Field {
+                        vis: Visibility::Public,
+                        ty: Type::Path {
+                            path: Path {
+                                segments: [
+                                    PathSegment {
+                                        ident: "String",
+                                        arguments: None,
+                                    },
+                                ],
+                            },
+                        },
+                    },
+                ],
+            },
+            semi_token: Some,
+        },
+    }
     "###);
 
     let data = match input.data {
         Data::Struct(data) => data,
         _ => panic!("expected a struct"),
     };
 
     snapshot!(data.fields.iter().collect::<Vec<_>>(), @r###"
-   ⋮[
-   ⋮    Field {
-   ⋮        vis: Inherited,
-   ⋮        ty: Type::Path {
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "i32",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮        },
-   ⋮    },
-   ⋮    Field {
-   ⋮        vis: Visibility::Public,
-   ⋮        ty: Type::Path {
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "String",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮        },
-   ⋮    },
-   ⋮]
+    [
+        Field {
+            vis: Inherited,
+            ty: Type::Path {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "i32",
+                            arguments: None,
+                        },
+                    ],
+                },
+            },
+        },
+        Field {
+            vis: Visibility::Public,
+            ty: Type::Path {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "String",
+                            arguments: None,
+                        },
+                    ],
+                },
+            },
+        },
+    ]
     "###);
 }
 
 #[test]
 fn test_ambiguous_crate() {
     let input = quote! {
         // The field type is `(crate::X)` not `crate (::X)`.
         struct S(crate::X);
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    vis: Inherited,
-   ⋮    ident: "S",
-   ⋮    generics: Generics,
-   ⋮    data: Data::Struct {
-   ⋮        fields: Fields::Unnamed {
-   ⋮            unnamed: [
-   ⋮                Field {
-   ⋮                    vis: Inherited,
-   ⋮                    ty: Type::Path {
-   ⋮                        path: Path {
-   ⋮                            segments: [
-   ⋮                                PathSegment {
-   ⋮                                    ident: "crate",
-   ⋮                                    arguments: None,
-   ⋮                                },
-   ⋮                                PathSegment {
-   ⋮                                    ident: "X",
-   ⋮                                    arguments: None,
-   ⋮                                },
-   ⋮                            ],
-   ⋮                        },
-   ⋮                    },
-   ⋮                },
-   ⋮            ],
-   ⋮        },
-   ⋮        semi_token: Some,
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        vis: Inherited,
+        ident: "S",
+        generics: Generics,
+        data: Data::Struct {
+            fields: Fields::Unnamed {
+                unnamed: [
+                    Field {
+                        vis: Inherited,
+                        ty: Type::Path {
+                            path: Path {
+                                segments: [
+                                    PathSegment {
+                                        ident: "crate",
+                                        arguments: None,
+                                    },
+                                    PathSegment {
+                                        ident: "X",
+                                        arguments: None,
+                                    },
+                                ],
+                            },
+                        },
+                    },
+                ],
+            },
+            semi_token: Some,
+        },
+    }
     "###);
 }
diff --git a/third_party/rust/syn/tests/test_expr.rs b/third_party/rust/syn/tests/test_expr.rs
--- a/third_party/rust/syn/tests/test_expr.rs
+++ b/third_party/rust/syn/tests/test_expr.rs
@@ -1,40 +1,302 @@
-extern crate proc_macro2;
-extern crate syn;
-
 #[macro_use]
 mod macros;
 
-use std::str::FromStr;
-
-use proc_macro2::TokenStream;
+use proc_macro2::{Delimiter, Group, Ident, Punct, Spacing, Span, TokenStream, TokenTree};
+use quote::quote;
+use std::iter::FromIterator;
 use syn::{Expr, ExprRange};
 
 #[test]
 fn test_expr_parse() {
-    let code = "..100u32";
-    let tt = TokenStream::from_str(code).unwrap();
-    let expr: Expr = syn::parse2(tt.clone()).unwrap();
-    let expr_range: ExprRange = syn::parse2(tt).unwrap();
-    assert_eq!(expr, Expr::Range(expr_range));
+    let tokens = quote!(..100u32);
+    snapshot!(tokens as Expr, @r###"
+    Expr::Range {
+        limits: HalfOpen,
+        to: Some(Expr::Lit {
+            lit: 100u32,
+        }),
+    }
+    "###);
+
+    let tokens = quote!(..100u32);
+    snapshot!(tokens as ExprRange, @r###"
+    ExprRange {
+        limits: HalfOpen,
+        to: Some(Expr::Lit {
+            lit: 100u32,
+        }),
+    }
+    "###);
 }
 
 #[test]
 fn test_await() {
     // Must not parse as Expr::Field.
-    let expr = syn::parse_str::<Expr>("fut.await").unwrap();
+    let tokens = quote!(fut.await);
 
-    snapshot!(expr, @r###"
-   ⋮Expr::Await {
-   ⋮    base: Expr::Path {
-   ⋮        path: Path {
-   ⋮            segments: [
-   ⋮                PathSegment {
-   ⋮                    ident: "fut",
-   ⋮                    arguments: None,
-   ⋮                },
-   ⋮            ],
-   ⋮        },
-   ⋮    },
-   ⋮}
+    snapshot!(tokens as Expr, @r###"
+    Expr::Await {
+        base: Expr::Path {
+            path: Path {
+                segments: [
+                    PathSegment {
+                        ident: "fut",
+                        arguments: None,
+                    },
+                ],
+            },
+        },
+    }
     "###);
 }
+
+#[rustfmt::skip]
+#[test]
+fn test_tuple_multi_index() {
+    for &input in &[
+        "tuple.0.0",
+        "tuple .0.0",
+        "tuple. 0.0",
+        "tuple.0 .0",
+        "tuple.0. 0",
+        "tuple . 0 . 0",
+    ] {
+        snapshot!(input as Expr, @r###"
+        Expr::Field {
+            base: Expr::Field {
+                base: Expr::Path {
+                    path: Path {
+                        segments: [
+                            PathSegment {
+                                ident: "tuple",
+                                arguments: None,
+                            },
+                        ],
+                    },
+                },
+                member: Unnamed(Index {
+                    index: 0,
+                }),
+            },
+            member: Unnamed(Index {
+                index: 0,
+            }),
+        }
+        "###);
+    }
+
+    for tokens in vec![
+        quote!(tuple.0.0),
+        quote!(tuple .0.0),
+        quote!(tuple. 0.0),
+        quote!(tuple.0 .0),
+        quote!(tuple.0. 0),
+        quote!(tuple . 0 . 0),
+    ] {
+        snapshot!(tokens as Expr, @r###"
+        Expr::Field {
+            base: Expr::Field {
+                base: Expr::Path {
+                    path: Path {
+                        segments: [
+                            PathSegment {
+                                ident: "tuple",
+                                arguments: None,
+                            },
+                        ],
+                    },
+                },
+                member: Unnamed(Index {
+                    index: 0,
+                }),
+            },
+            member: Unnamed(Index {
+                index: 0,
+            }),
+        }
+        "###);
+    }
+}
+
+#[test]
+fn test_macro_variable_func() {
+    // mimics the token stream corresponding to `$fn()`
+    let tokens = TokenStream::from_iter(vec![
+        TokenTree::Group(Group::new(Delimiter::None, quote! { f })),
+        TokenTree::Group(Group::new(Delimiter::Parenthesis, TokenStream::new())),
+    ]);
+
+    snapshot!(tokens as Expr, @r###"
+    Expr::Call {
+        func: Expr::Group {
+            expr: Expr::Path {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "f",
+                            arguments: None,
+                        },
+                    ],
+                },
+            },
+        },
+    }
+    "###);
+
+    let tokens = TokenStream::from_iter(vec![
+        TokenTree::Punct(Punct::new('#', Spacing::Alone)),
+        TokenTree::Group(Group::new(Delimiter::Bracket, quote! { outside })),
+        TokenTree::Group(Group::new(Delimiter::None, quote! { #[inside] f })),
+        TokenTree::Group(Group::new(Delimiter::Parenthesis, TokenStream::new())),
+    ]);
+
+    snapshot!(tokens as Expr, @r###"
+    Expr::Call {
+        attrs: [
+            Attribute {
+                style: Outer,
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "outside",
+                            arguments: None,
+                        },
+                    ],
+                },
+                tokens: TokenStream(``),
+            },
+        ],
+        func: Expr::Group {
+            expr: Expr::Path {
+                attrs: [
+                    Attribute {
+                        style: Outer,
+                        path: Path {
+                            segments: [
+                                PathSegment {
+                                    ident: "inside",
+                                    arguments: None,
+                                },
+                            ],
+                        },
+                        tokens: TokenStream(``),
+                    },
+                ],
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "f",
+                            arguments: None,
+                        },
+                    ],
+                },
+            },
+        },
+    }
+    "###);
+}
+
+#[test]
+fn test_macro_variable_macro() {
+    // mimics the token stream corresponding to `$macro!()`
+    let tokens = TokenStream::from_iter(vec![
+        TokenTree::Group(Group::new(Delimiter::None, quote! { m })),
+        TokenTree::Punct(Punct::new('!', Spacing::Alone)),
+        TokenTree::Group(Group::new(Delimiter::Parenthesis, TokenStream::new())),
+    ]);
+
+    snapshot!(tokens as Expr, @r###"
+    Expr::Macro {
+        mac: Macro {
+            path: Path {
+                segments: [
+                    PathSegment {
+                        ident: "m",
+                        arguments: None,
+                    },
+                ],
+            },
+            delimiter: Paren,
+            tokens: TokenStream(``),
+        },
+    }
+    "###);
+}
+
+#[test]
+fn test_macro_variable_struct() {
+    // mimics the token stream corresponding to `$struct {}`
+    let tokens = TokenStream::from_iter(vec![
+        TokenTree::Group(Group::new(Delimiter::None, quote! { S })),
+        TokenTree::Group(Group::new(Delimiter::Brace, TokenStream::new())),
+    ]);
+
+    snapshot!(tokens as Expr, @r###"
+    Expr::Struct {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "S",
+                    arguments: None,
+                },
+            ],
+        },
+    }
+    "###);
+}
+
+#[test]
+fn test_macro_variable_match_arm() {
+    // mimics the token stream corresponding to `match v { _ => $expr }`
+    let tokens = TokenStream::from_iter(vec![
+        TokenTree::Ident(Ident::new("match", Span::call_site())),
+        TokenTree::Ident(Ident::new("v", Span::call_site())),
+        TokenTree::Group(Group::new(
+            Delimiter::Brace,
+            TokenStream::from_iter(vec![
+                TokenTree::Punct(Punct::new('_', Spacing::Alone)),
+                TokenTree::Punct(Punct::new('=', Spacing::Joint)),
+                TokenTree::Punct(Punct::new('>', Spacing::Alone)),
+                TokenTree::Group(Group::new(Delimiter::None, quote! { #[a] () })),
+            ]),
+        )),
+    ]);
+
+    snapshot!(tokens as Expr, @r###"
+    Expr::Match {
+        expr: Expr::Path {
+            path: Path {
+                segments: [
+                    PathSegment {
+                        ident: "v",
+                        arguments: None,
+                    },
+                ],
+            },
+        },
+        arms: [
+            Arm {
+                pat: Pat::Wild,
+                body: Expr::Group {
+                    expr: Expr::Tuple {
+                        attrs: [
+                            Attribute {
+                                style: Outer,
+                                path: Path {
+                                    segments: [
+                                        PathSegment {
+                                            ident: "a",
+                                            arguments: None,
+                                        },
+                                    ],
+                                },
+                                tokens: TokenStream(``),
+                            },
+                        ],
+                    },
+                },
+            },
+        ],
+    }
+    "###);
+}
diff --git a/third_party/rust/syn/tests/test_generics.rs b/third_party/rust/syn/tests/test_generics.rs
--- a/third_party/rust/syn/tests/test_generics.rs
+++ b/third_party/rust/syn/tests/test_generics.rs
@@ -1,110 +1,105 @@
-extern crate quote;
-extern crate syn;
-
-mod features;
-
 #[macro_use]
 mod macros;
 
 use quote::quote;
 use syn::{DeriveInput, ItemFn, TypeParamBound, WhereClause, WherePredicate};
 
 #[test]
 fn test_split_for_impl() {
     let input = quote! {
         struct S<'a, 'b: 'a, #[may_dangle] T: 'a = ()> where T: Debug;
     };
 
     snapshot!(input as DeriveInput, @r###"
-   ⋮DeriveInput {
-   ⋮    vis: Inherited,
-   ⋮    ident: "S",
-   ⋮    generics: Generics {
-   ⋮        lt_token: Some,
-   ⋮        params: [
-   ⋮            Lifetime(LifetimeDef {
-   ⋮                lifetime: Lifetime {
-   ⋮                    ident: "a",
-   ⋮                },
-   ⋮            }),
-   ⋮            Lifetime(LifetimeDef {
-   ⋮                lifetime: Lifetime {
-   ⋮                    ident: "b",
-   ⋮                },
-   ⋮                colon_token: Some,
-   ⋮                bounds: [
-   ⋮                    Lifetime {
-   ⋮                        ident: "a",
-   ⋮                    },
-   ⋮                ],
-   ⋮            }),
-   ⋮            Type(TypeParam {
-   ⋮                attrs: [
-   ⋮                    Attribute {
-   ⋮                        style: Outer,
-   ⋮                        path: Path {
-   ⋮                            segments: [
-   ⋮                                PathSegment {
-   ⋮                                    ident: "may_dangle",
-   ⋮                                    arguments: None,
-   ⋮                                },
-   ⋮                            ],
-   ⋮                        },
-   ⋮                        tokens: ``,
-   ⋮                    },
-   ⋮                ],
-   ⋮                ident: "T",
-   ⋮                colon_token: Some,
-   ⋮                bounds: [
-   ⋮                    Lifetime(Lifetime {
-   ⋮                        ident: "a",
-   ⋮                    }),
-   ⋮                ],
-   ⋮                eq_token: Some,
-   ⋮                default: Some(Type::Tuple),
-   ⋮            }),
-   ⋮        ],
-   ⋮        gt_token: Some,
-   ⋮        where_clause: Some(WhereClause {
-   ⋮            predicates: [
-   ⋮                Type(PredicateType {
-   ⋮                    bounded_ty: Type::Path {
-   ⋮                        path: Path {
-   ⋮                            segments: [
-   ⋮                                PathSegment {
-   ⋮                                    ident: "T",
-   ⋮                                    arguments: None,
-   ⋮                                },
-   ⋮                            ],
-   ⋮                        },
-   ⋮                    },
-   ⋮                    bounds: [
-   ⋮                        Trait(TraitBound {
-   ⋮                            modifier: None,
-   ⋮                            path: Path {
-   ⋮                                segments: [
-   ⋮                                    PathSegment {
-   ⋮                                        ident: "Debug",
-   ⋮                                        arguments: None,
-   ⋮                                    },
-   ⋮                                ],
-   ⋮                            },
-   ⋮                        }),
-   ⋮                    ],
-   ⋮                }),
-   ⋮            ],
-   ⋮        }),
-   ⋮    },
-   ⋮    data: Data::Struct {
-   ⋮        fields: Unit,
-   ⋮        semi_token: Some,
-   ⋮    },
-   ⋮}
+    DeriveInput {
+        vis: Inherited,
+        ident: "S",
+        generics: Generics {
+            lt_token: Some,
+            params: [
+                Lifetime(LifetimeDef {
+                    lifetime: Lifetime {
+                        ident: "a",
+                    },
+                }),
+                Lifetime(LifetimeDef {
+                    lifetime: Lifetime {
+                        ident: "b",
+                    },
+                    colon_token: Some,
+                    bounds: [
+                        Lifetime {
+                            ident: "a",
+                        },
+                    ],
+                }),
+                Type(TypeParam {
+                    attrs: [
+                        Attribute {
+                            style: Outer,
+                            path: Path {
+                                segments: [
+                                    PathSegment {
+                                        ident: "may_dangle",
+                                        arguments: None,
+                                    },
+                                ],
+                            },
+                            tokens: TokenStream(``),
+                        },
+                    ],
+                    ident: "T",
+                    colon_token: Some,
+                    bounds: [
+                        Lifetime(Lifetime {
+                            ident: "a",
+                        }),
+                    ],
+                    eq_token: Some,
+                    default: Some(Type::Tuple),
+                }),
+            ],
+            gt_token: Some,
+            where_clause: Some(WhereClause {
+                predicates: [
+                    Type(PredicateType {
+                        bounded_ty: Type::Path {
+                            path: Path {
+                                segments: [
+                                    PathSegment {
+                                        ident: "T",
+                                        arguments: None,
+                                    },
+                                ],
+                            },
+                        },
+                        bounds: [
+                            Trait(TraitBound {
+                                modifier: None,
+                                path: Path {
+                                    segments: [
+                                        PathSegment {
+                                            ident: "Debug",
+                                            arguments: None,
+                                        },
+                                    ],
+                                },
+                            }),
+                        ],
+                    }),
+                ],
+            }),
+        },
+        data: Data::Struct {
+            fields: Unit,
+            semi_token: Some,
+        },
+    }
     "###);
 
     let generics = input.generics;
     let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
 
     let generated = quote! {
         impl #impl_generics MyTrait for Test #ty_generics #where_clause {}
     };
@@ -126,156 +121,156 @@ fn test_split_for_impl() {
     };
     assert_eq!(generated.to_string(), expected.to_string());
 }
 
 #[test]
 fn test_ty_param_bound() {
     let tokens = quote!('a);
     snapshot!(tokens as TypeParamBound, @r###"
-   ⋮Lifetime(Lifetime {
-   ⋮    ident: "a",
-   ⋮})
+    Lifetime(Lifetime {
+        ident: "a",
+    })
     "###);
 
     let tokens = quote!('_);
     snapshot!(tokens as TypeParamBound, @r###"
-   ⋮Lifetime(Lifetime {
-   ⋮    ident: "_",
-   ⋮})
+    Lifetime(Lifetime {
+        ident: "_",
+    })
     "###);
 
     let tokens = quote!(Debug);
     snapshot!(tokens as TypeParamBound, @r###"
-   ⋮Trait(TraitBound {
-   ⋮    modifier: None,
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "Debug",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮})
+    Trait(TraitBound {
+        modifier: None,
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "Debug",
+                    arguments: None,
+                },
+            ],
+        },
+    })
     "###);
 
     let tokens = quote!(?Sized);
     snapshot!(tokens as TypeParamBound, @r###"
-   ⋮Trait(TraitBound {
-   ⋮    modifier: Maybe,
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "Sized",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮})
+    Trait(TraitBound {
+        modifier: Maybe,
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "Sized",
+                    arguments: None,
+                },
+            ],
+        },
+    })
     "###);
 }
 
 #[test]
 fn test_fn_precedence_in_where_clause() {
     // This should parse as two separate bounds, `FnOnce() -> i32` and `Send` - not
     // `FnOnce() -> (i32 + Send)`.
     let input = quote! {
         fn f<G>()
         where
             G: FnOnce() -> i32 + Send,
         {
         }
     };
 
     snapshot!(input as ItemFn, @r###"
-   ⋮ItemFn {
-   ⋮    vis: Inherited,
-   ⋮    sig: Signature {
-   ⋮        ident: "f",
-   ⋮        generics: Generics {
-   ⋮            lt_token: Some,
-   ⋮            params: [
-   ⋮                Type(TypeParam {
-   ⋮                    ident: "G",
-   ⋮                }),
-   ⋮            ],
-   ⋮            gt_token: Some,
-   ⋮            where_clause: Some(WhereClause {
-   ⋮                predicates: [
-   ⋮                    Type(PredicateType {
-   ⋮                        bounded_ty: Type::Path {
-   ⋮                            path: Path {
-   ⋮                                segments: [
-   ⋮                                    PathSegment {
-   ⋮                                        ident: "G",
-   ⋮                                        arguments: None,
-   ⋮                                    },
-   ⋮                                ],
-   ⋮                            },
-   ⋮                        },
-   ⋮                        bounds: [
-   ⋮                            Trait(TraitBound {
-   ⋮                                modifier: None,
-   ⋮                                path: Path {
-   ⋮                                    segments: [
-   ⋮                                        PathSegment {
-   ⋮                                            ident: "FnOnce",
-   ⋮                                            arguments: PathArguments::Parenthesized {
-   ⋮                                                output: Type(
-   ⋮                                                    Type::Path {
-   ⋮                                                        path: Path {
-   ⋮                                                            segments: [
-   ⋮                                                                PathSegment {
-   ⋮                                                                    ident: "i32",
-   ⋮                                                                    arguments: None,
-   ⋮                                                                },
-   ⋮                                                            ],
-   ⋮                                                        },
-   ⋮                                                    },
-   ⋮                                                ),
-   ⋮                                            },
-   ⋮                                        },
-   ⋮                                    ],
-   ⋮                                },
-   ⋮                            }),
-   ⋮                            Trait(TraitBound {
-   ⋮                                modifier: None,
-   ⋮                                path: Path {
-   ⋮                                    segments: [
-   ⋮                                        PathSegment {
-   ⋮                                            ident: "Send",
-   ⋮                                            arguments: None,
-   ⋮                                        },
-   ⋮                                    ],
-   ⋮                                },
-   ⋮                            }),
-   ⋮                        ],
-   ⋮                    }),
-   ⋮                ],
-   ⋮            }),
-   ⋮        },
-   ⋮        output: Default,
-   ⋮    },
-   ⋮    block: Block,
-   ⋮}
+    ItemFn {
+        vis: Inherited,
+        sig: Signature {
+            ident: "f",
+            generics: Generics {
+                lt_token: Some,
+                params: [
+                    Type(TypeParam {
+                        ident: "G",
+                    }),
+                ],
+                gt_token: Some,
+                where_clause: Some(WhereClause {
+                    predicates: [
+                        Type(PredicateType {
+                            bounded_ty: Type::Path {
+                                path: Path {
+                                    segments: [
+                                        PathSegment {
+                                            ident: "G",
+                                            arguments: None,
+                                        },
+                                    ],
+                                },
+                            },
+                            bounds: [
+                                Trait(TraitBound {
+                                    modifier: None,
+                                    path: Path {
+                                        segments: [
+                                            PathSegment {
+                                                ident: "FnOnce",
+                                                arguments: PathArguments::Parenthesized {
+                                                    output: Type(
+                                                        Type::Path {
+                                                            path: Path {
+                                                                segments: [
+                                                                    PathSegment {
+                                                                        ident: "i32",
+                                                                        arguments: None,
+                                                                    },
+                                                                ],
+                                                            },
+                                                        },
+                                                    ),
+                                                },
+                                            },
+                                        ],
+                                    },
+                                }),
+                                Trait(TraitBound {
+                                    modifier: None,
+                                    path: Path {
+                                        segments: [
+                                            PathSegment {
+                                                ident: "Send",
+                                                arguments: None,
+                                            },
+                                        ],
+                                    },
+                                }),
+                            ],
+                        }),
+                    ],
+                }),
+            },
+            output: Default,
+        },
+        block: Block,
+    }
     "###);
 
     let where_clause = input.sig.generics.where_clause.as_ref().unwrap();
     assert_eq!(where_clause.predicates.len(), 1);
 
     let predicate = match &where_clause.predicates[0] {
         WherePredicate::Type(pred) => pred,
         _ => panic!("wrong predicate kind"),
     };
 
     assert_eq!(predicate.bounds.len(), 2, "{:#?}", predicate.bounds);
 
     let first_bound = &predicate.bounds[0];
-    assert_eq!(quote!(#first_bound).to_string(), "FnOnce ( ) -> i32");
+    assert_eq!(quote!(#first_bound).to_string(), "FnOnce () -> i32");
 
     let second_bound = &predicate.bounds[1];
     assert_eq!(quote!(#second_bound).to_string(), "Send");
 }
 
 #[test]
 fn test_where_clause_at_end_of_input() {
     let input = quote! {
diff --git a/third_party/rust/syn/tests/test_grouping.rs b/third_party/rust/syn/tests/test_grouping.rs
--- a/third_party/rust/syn/tests/test_grouping.rs
+++ b/third_party/rust/syn/tests/test_grouping.rs
@@ -1,13 +1,8 @@
-extern crate proc_macro2;
-extern crate syn;
-
-mod features;
-
 #[macro_use]
 mod macros;
 
 use proc_macro2::{Delimiter, Group, Literal, Punct, Spacing, TokenStream, TokenTree};
 use syn::Expr;
 
 use std::iter::FromIterator;
 
@@ -23,36 +18,36 @@ fn test_grouping() {
                 TokenTree::Punct(Punct::new('+', Spacing::Alone)),
                 TokenTree::Literal(Literal::i32_suffixed(3)),
             ]),
         )),
         TokenTree::Punct(Punct::new('*', Spacing::Alone)),
         TokenTree::Literal(Literal::i32_suffixed(4)),
     ]);
 
-    assert_eq!(tokens.to_string(), "1i32 +  2i32 + 3i32  * 4i32");
+    assert_eq!(tokens.to_string(), "1i32 + 2i32 + 3i32 * 4i32");
 
     snapshot!(tokens as Expr, @r###"
-   ⋮Expr::Binary {
-   ⋮    left: Expr::Lit {
-   ⋮        lit: 1i32,
-   ⋮    },
-   ⋮    op: Add,
-   ⋮    right: Expr::Binary {
-   ⋮        left: Expr::Group {
-   ⋮            expr: Expr::Binary {
-   ⋮                left: Expr::Lit {
-   ⋮                    lit: 2i32,
-   ⋮                },
-   ⋮                op: Add,
-   ⋮                right: Expr::Lit {
-   ⋮                    lit: 3i32,
-   ⋮                },
-   ⋮            },
-   ⋮        },
-   ⋮        op: Mul,
-   ⋮        right: Expr::Lit {
-   ⋮            lit: 4i32,
-   ⋮        },
-   ⋮    },
-   ⋮}
+    Expr::Binary {
+        left: Expr::Lit {
+            lit: 1i32,
+        },
+        op: Add,
+        right: Expr::Binary {
+            left: Expr::Group {
+                expr: Expr::Binary {
+                    left: Expr::Lit {
+                        lit: 2i32,
+                    },
+                    op: Add,
+                    right: Expr::Lit {
+                        lit: 3i32,
+                    },
+                },
+            },
+            op: Mul,
+            right: Expr::Lit {
+                lit: 4i32,
+            },
+        },
+    }
     "###);
 }
diff --git a/third_party/rust/syn/tests/test_ident.rs b/third_party/rust/syn/tests/test_ident.rs
--- a/third_party/rust/syn/tests/test_ident.rs
+++ b/third_party/rust/syn/tests/test_ident.rs
@@ -1,13 +1,8 @@
-extern crate proc_macro2;
-extern crate syn;
-
-mod features;
-
 use proc_macro2::{Ident, Span, TokenStream};
 use std::str::FromStr;
 use syn::Result;
 
 fn parse(s: &str) -> Result<Ident> {
     syn::parse2(TokenStream::from_str(s).unwrap())
 }
 
diff --git a/third_party/rust/syn/tests/test_item.rs b/third_party/rust/syn/tests/test_item.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/tests/test_item.rs
@@ -0,0 +1,45 @@
+#[macro_use]
+mod macros;
+
+use proc_macro2::{Delimiter, Group, Ident, Span, TokenStream, TokenTree};
+use quote::quote;
+use std::iter::FromIterator;
+use syn::Item;
+
+#[test]
+fn test_macro_variable_attr() {
+    // mimics the token stream corresponding to `$attr fn f() {}`
+    let tokens = TokenStream::from_iter(vec![
+        TokenTree::Group(Group::new(Delimiter::None, quote! { #[test] })),
+        TokenTree::Ident(Ident::new("fn", Span::call_site())),
+        TokenTree::Ident(Ident::new("f", Span::call_site())),
+        TokenTree::Group(Group::new(Delimiter::Parenthesis, TokenStream::new())),
+        TokenTree::Group(Group::new(Delimiter::Brace, TokenStream::new())),
+    ]);
+
+    snapshot!(tokens as Item, @r###"
+    Item::Fn {
+        attrs: [
+            Attribute {
+                style: Outer,
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "test",
+                            arguments: None,
+                        },
+                    ],
+                },
+                tokens: TokenStream(``),
+            },
+        ],
+        vis: Inherited,
+        sig: Signature {
+            ident: "f",
+            generics: Generics,
+            output: Default,
+        },
+        block: Block,
+    }
+    "###);
+}
diff --git a/third_party/rust/syn/tests/test_iterators.rs b/third_party/rust/syn/tests/test_iterators.rs
--- a/third_party/rust/syn/tests/test_iterators.rs
+++ b/third_party/rust/syn/tests/test_iterators.rs
@@ -1,15 +1,10 @@
 use syn::punctuated::{Pair, Punctuated};
-
-extern crate quote;
-#[macro_use]
-extern crate syn;
-
-mod features;
+use syn::Token;
 
 #[macro_use]
 mod macros;
 
 macro_rules! check_exact_size_iterator {
     ($iter:expr) => {{
         let iter = $iter;
         let size_hint = iter.size_hint();
diff --git a/third_party/rust/syn/tests/test_lit.rs b/third_party/rust/syn/tests/test_lit.rs
--- a/third_party/rust/syn/tests/test_lit.rs
+++ b/third_party/rust/syn/tests/test_lit.rs
@@ -1,18 +1,16 @@
-extern crate proc_macro2;
-extern crate quote;
-extern crate syn;
+#[macro_use]
+mod macros;
 
-mod features;
-
-use proc_macro2::{TokenStream, TokenTree};
+use proc_macro2::{Delimiter, Group, Literal, Span, TokenStream, TokenTree};
 use quote::ToTokens;
+use std::iter::FromIterator;
 use std::str::FromStr;
-use syn::Lit;
+use syn::{Lit, LitFloat, LitInt};
 
 fn lit(s: &str) -> Lit {
     match TokenStream::from_str(s)
         .unwrap()
         .into_iter()
         .next()
         .unwrap()
     {
@@ -45,16 +43,19 @@ fn strings() {
     test_string("\"'\"", "'");
     test_string("\"\"", "");
     test_string("\"\\u{1F415}\"", "\u{1F415}");
     test_string(
         "\"contains\nnewlines\\\nescaped newlines\"",
         "contains\nnewlinesescaped newlines",
     );
     test_string("r\"raw\nstring\\\nhere\"", "raw\nstring\\\nhere");
+    test_string("\"...\"q", "...");
+    test_string("r\"...\"q", "...");
+    test_string("r##\"...\"##q", "...");
 }
 
 #[test]
 fn byte_strings() {
     fn test_byte_string(s: &str, value: &[u8]) {
         match lit(s) {
             Lit::ByteStr(lit) => {
                 assert_eq!(lit.value(), value);
@@ -74,16 +75,19 @@ fn byte_strings() {
     test_byte_string("b\"\\\"\"", b"\"");
     test_byte_string("b\"'\"", b"'");
     test_byte_string("b\"\"", b"");
     test_byte_string(
         "b\"contains\nnewlines\\\nescaped newlines\"",
         b"contains\nnewlinesescaped newlines",
     );
     test_byte_string("br\"raw\nstring\\\nhere\"", b"raw\nstring\\\nhere");
+    test_byte_string("b\"...\"q", b"...");
+    test_byte_string("br\"...\"q", b"...");
+    test_byte_string("br##\"...\"##q", b"...");
 }
 
 #[test]
 fn bytes() {
     fn test_byte(s: &str, value: u8) {
         match lit(s) {
             Lit::Byte(lit) => {
                 assert_eq!(lit.value(), value);
@@ -95,16 +99,17 @@ fn bytes() {
     }
 
     test_byte("b'a'", b'a');
     test_byte("b'\\n'", b'\n');
     test_byte("b'\\r'", b'\r');
     test_byte("b'\\t'", b'\t');
     test_byte("b'\\''", b'\'');
     test_byte("b'\"'", b'"');
+    test_byte("b'a'q", b'a');
 }
 
 #[test]
 fn chars() {
     fn test_char(s: &str, value: char) {
         match lit(s) {
             Lit::Char(lit) => {
                 assert_eq!(lit.value(), value);
@@ -120,16 +125,17 @@ fn chars() {
     test_char("'a'", 'a');
     test_char("'\\n'", '\n');
     test_char("'\\r'", '\r');
     test_char("'\\t'", '\t');
     test_char("'🐕'", '🐕'); // NOTE: This is an emoji
     test_char("'\\''", '\'');
     test_char("'\"'", '"');
     test_char("'\\u{1F415}'", '\u{1F415}');
+    test_char("'a'q", 'a');
 }
 
 #[test]
 fn ints() {
     fn test_int(s: &str, value: u64, suffix: &str) {
         match lit(s) {
             Lit::Int(lit) => {
                 assert_eq!(lit.base10_digits().parse::<u64>().unwrap(), value);
@@ -180,9 +186,64 @@ fn floats() {
         }
     }
 
     test_float("5.5", 5.5, "");
     test_float("5.5E12", 5.5e12, "");
     test_float("5.5e12", 5.5e12, "");
     test_float("1.0__3e-12", 1.03e-12, "");
     test_float("1.03e+12", 1.03e12, "");
+    test_float("9e99e99", 9e99, "e99");
 }
+
+#[test]
+fn negative() {
+    let span = Span::call_site();
+    assert_eq!("-1", LitInt::new("-1", span).to_string());
+    assert_eq!("-1i8", LitInt::new("-1i8", span).to_string());
+    assert_eq!("-1i16", LitInt::new("-1i16", span).to_string());
+    assert_eq!("-1i32", LitInt::new("-1i32", span).to_string());
+    assert_eq!("-1i64", LitInt::new("-1i64", span).to_string());
+    assert_eq!("-1.5", LitFloat::new("-1.5", span).to_string());
+    assert_eq!("-1.5f32", LitFloat::new("-1.5f32", span).to_string());
+    assert_eq!("-1.5f64", LitFloat::new("-1.5f64", span).to_string());
+}
+
+#[test]
+fn suffix() {
+    fn get_suffix(token: &str) -> String {
+        let lit = syn::parse_str::<Lit>(token).unwrap();
+        match lit {
+            Lit::Str(lit) => lit.suffix().to_owned(),
+            Lit::ByteStr(lit) => lit.suffix().to_owned(),
+            Lit::Byte(lit) => lit.suffix().to_owned(),
+            Lit::Char(lit) => lit.suffix().to_owned(),
+            Lit::Int(lit) => lit.suffix().to_owned(),
+            Lit::Float(lit) => lit.suffix().to_owned(),
+            _ => unimplemented!(),
+        }
+    }
+
+    assert_eq!(get_suffix("\"\"s"), "s");
+    assert_eq!(get_suffix("r\"\"r"), "r");
+    assert_eq!(get_suffix("b\"\"b"), "b");
+    assert_eq!(get_suffix("br\"\"br"), "br");
+    assert_eq!(get_suffix("r#\"\"#r"), "r");
+    assert_eq!(get_suffix("'c'c"), "c");
+    assert_eq!(get_suffix("b'b'b"), "b");
+    assert_eq!(get_suffix("1i32"), "i32");
+    assert_eq!(get_suffix("1_i32"), "i32");
+    assert_eq!(get_suffix("1.0f32"), "f32");
+    assert_eq!(get_suffix("1.0_f32"), "f32");
+}
+
+#[test]
+fn test_deep_group_empty() {
+    let tokens = TokenStream::from_iter(vec![TokenTree::Group(Group::new(
+        Delimiter::None,
+        TokenStream::from_iter(vec![TokenTree::Group(Group::new(
+            Delimiter::None,
+            TokenStream::from_iter(vec![TokenTree::Literal(Literal::string("hi"))]),
+        ))]),
+    ))]);
+
+    snapshot!(tokens as Lit, @r#""hi""# );
+}
diff --git a/third_party/rust/syn/tests/test_meta.rs b/third_party/rust/syn/tests/test_meta.rs
--- a/third_party/rust/syn/tests/test_meta.rs
+++ b/third_party/rust/syn/tests/test_meta.rs
@@ -1,343 +1,339 @@
-extern crate syn;
-
-mod features;
-
 #[macro_use]
 mod macros;
 
 use syn::{Meta, MetaList, MetaNameValue, NestedMeta};
 
 #[test]
 fn test_parse_meta_item_word() {
     let input = "hello";
 
     snapshot!(input as Meta, @r###"
-   ⋮Path(Path {
-   ⋮    segments: [
-   ⋮        PathSegment {
-   ⋮            ident: "hello",
-   ⋮            arguments: None,
-   ⋮        },
-   ⋮    ],
-   ⋮})
+    Path(Path {
+        segments: [
+            PathSegment {
+                ident: "hello",
+                arguments: None,
+            },
+        ],
+    })
     "###);
 }
 
 #[test]
 fn test_parse_meta_name_value() {
     let input = "foo = 5";
     let (inner, meta) = (input, input);
 
     snapshot!(inner as MetaNameValue, @r###"
-   ⋮MetaNameValue {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "foo",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    lit: 5,
-   ⋮}
+    MetaNameValue {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "foo",
+                    arguments: None,
+                },
+            ],
+        },
+        lit: 5,
+    }
     "###);
 
     snapshot!(meta as Meta, @r###"
-   ⋮Meta::NameValue {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "foo",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    lit: 5,
-   ⋮}
+    Meta::NameValue {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "foo",
+                    arguments: None,
+                },
+            ],
+        },
+        lit: 5,
+    }
     "###);
 
     assert_eq!(meta, inner.into());
 }
 
 #[test]
 fn test_parse_meta_name_value_with_keyword() {
     let input = "static = 5";
     let (inner, meta) = (input, input);
 
     snapshot!(inner as MetaNameValue, @r###"
-   ⋮MetaNameValue {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "static",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    lit: 5,
-   ⋮}
+    MetaNameValue {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "static",
+                    arguments: None,
+                },
+            ],
+        },
+        lit: 5,
+    }
     "###);
 
     snapshot!(meta as Meta, @r###"
-   ⋮Meta::NameValue {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "static",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    lit: 5,
-   ⋮}
+    Meta::NameValue {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "static",
+                    arguments: None,
+                },
+            ],
+        },
+        lit: 5,
+    }
     "###);
 
     assert_eq!(meta, inner.into());
 }
 
 #[test]
 fn test_parse_meta_name_value_with_bool() {
     let input = "true = 5";
     let (inner, meta) = (input, input);
 
     snapshot!(inner as MetaNameValue, @r###"
-   ⋮MetaNameValue {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "true",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    lit: 5,
-   ⋮}
+    MetaNameValue {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "true",
+                    arguments: None,
+                },
+            ],
+        },
+        lit: 5,
+    }
     "###);
 
     snapshot!(meta as Meta, @r###"
-   ⋮Meta::NameValue {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "true",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    lit: 5,
-   ⋮}
+    Meta::NameValue {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "true",
+                    arguments: None,
+                },
+            ],
+        },
+        lit: 5,
+    }
     "###);
 
     assert_eq!(meta, inner.into());
 }
 
 #[test]
 fn test_parse_meta_item_list_lit() {
     let input = "foo(5)";
     let (inner, meta) = (input, input);
 
     snapshot!(inner as MetaList, @r###"
-   ⋮MetaList {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "foo",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    nested: [
-   ⋮        Lit(5),
-   ⋮    ],
-   ⋮}
+    MetaList {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "foo",
+                    arguments: None,
+                },
+            ],
+        },
+        nested: [
+            Lit(5),
+        ],
+    }
     "###);
 
     snapshot!(meta as Meta, @r###"
-   ⋮Meta::List {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "foo",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    nested: [
-   ⋮        Lit(5),
-   ⋮    ],
-   ⋮}
+    Meta::List {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "foo",
+                    arguments: None,
+                },
+            ],
+        },
+        nested: [
+            Lit(5),
+        ],
+    }
     "###);
 
     assert_eq!(meta, inner.into());
 }
 
 #[test]
 fn test_parse_meta_item_multiple() {
     let input = "foo(word, name = 5, list(name2 = 6), word2)";
     let (inner, meta) = (input, input);
 
     snapshot!(inner as MetaList, @r###"
-   ⋮MetaList {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "foo",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    nested: [
-   ⋮        Meta(Path(Path {
-   ⋮            segments: [
-   ⋮                PathSegment {
-   ⋮                    ident: "word",
-   ⋮                    arguments: None,
-   ⋮                },
-   ⋮            ],
-   ⋮        })),
-   ⋮        Meta(Meta::NameValue {
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "name",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮            lit: 5,
-   ⋮        }),
-   ⋮        Meta(Meta::List {
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "list",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮            nested: [
-   ⋮                Meta(Meta::NameValue {
-   ⋮                    path: Path {
-   ⋮                        segments: [
-   ⋮                            PathSegment {
-   ⋮                                ident: "name2",
-   ⋮                                arguments: None,
-   ⋮                            },
-   ⋮                        ],
-   ⋮                    },
-   ⋮                    lit: 6,
-   ⋮                }),
-   ⋮            ],
-   ⋮        }),
-   ⋮        Meta(Path(Path {
-   ⋮            segments: [
-   ⋮                PathSegment {
-   ⋮                    ident: "word2",
-   ⋮                    arguments: None,
-   ⋮                },
-   ⋮            ],
-   ⋮        })),
-   ⋮    ],
-   ⋮}
+    MetaList {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "foo",
+                    arguments: None,
+                },
+            ],
+        },
+        nested: [
+            Meta(Path(Path {
+                segments: [
+                    PathSegment {
+                        ident: "word",
+                        arguments: None,
+                    },
+                ],
+            })),
+            Meta(Meta::NameValue {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "name",
+                            arguments: None,
+                        },
+                    ],
+                },
+                lit: 5,
+            }),
+            Meta(Meta::List {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "list",
+                            arguments: None,
+                        },
+                    ],
+                },
+                nested: [
+                    Meta(Meta::NameValue {
+                        path: Path {
+                            segments: [
+                                PathSegment {
+                                    ident: "name2",
+                                    arguments: None,
+                                },
+                            ],
+                        },
+                        lit: 6,
+                    }),
+                ],
+            }),
+            Meta(Path(Path {
+                segments: [
+                    PathSegment {
+                        ident: "word2",
+                        arguments: None,
+                    },
+                ],
+            })),
+        ],
+    }
     "###);
 
     snapshot!(meta as Meta, @r###"
-   ⋮Meta::List {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "foo",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    nested: [
-   ⋮        Meta(Path(Path {
-   ⋮            segments: [
-   ⋮                PathSegment {
-   ⋮                    ident: "word",
-   ⋮                    arguments: None,
-   ⋮                },
-   ⋮            ],
-   ⋮        })),
-   ⋮        Meta(Meta::NameValue {
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "name",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮            lit: 5,
-   ⋮        }),
-   ⋮        Meta(Meta::List {
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "list",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮            nested: [
-   ⋮                Meta(Meta::NameValue {
-   ⋮                    path: Path {
-   ⋮                        segments: [
-   ⋮                            PathSegment {
-   ⋮                                ident: "name2",
-   ⋮                                arguments: None,
-   ⋮                            },
-   ⋮                        ],
-   ⋮                    },
-   ⋮                    lit: 6,
-   ⋮                }),
-   ⋮            ],
-   ⋮        }),
-   ⋮        Meta(Path(Path {
-   ⋮            segments: [
-   ⋮                PathSegment {
-   ⋮                    ident: "word2",
-   ⋮                    arguments: None,
-   ⋮                },
-   ⋮            ],
-   ⋮        })),
-   ⋮    ],
-   ⋮}
+    Meta::List {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "foo",
+                    arguments: None,
+                },
+            ],
+        },
+        nested: [
+            Meta(Path(Path {
+                segments: [
+                    PathSegment {
+                        ident: "word",
+                        arguments: None,
+                    },
+                ],
+            })),
+            Meta(Meta::NameValue {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "name",
+                            arguments: None,
+                        },
+                    ],
+                },
+                lit: 5,
+            }),
+            Meta(Meta::List {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "list",
+                            arguments: None,
+                        },
+                    ],
+                },
+                nested: [
+                    Meta(Meta::NameValue {
+                        path: Path {
+                            segments: [
+                                PathSegment {
+                                    ident: "name2",
+                                    arguments: None,
+                                },
+                            ],
+                        },
+                        lit: 6,
+                    }),
+                ],
+            }),
+            Meta(Path(Path {
+                segments: [
+                    PathSegment {
+                        ident: "word2",
+                        arguments: None,
+                    },
+                ],
+            })),
+        ],
+    }
     "###);
 
     assert_eq!(meta, inner.into());
 }
 
 #[test]
 fn test_parse_nested_meta() {
     let input = "5";
     snapshot!(input as NestedMeta, @"Lit(5)");
 
     let input = "list(name2 = 6)";
     snapshot!(input as NestedMeta, @r###"
-   ⋮Meta(Meta::List {
-   ⋮    path: Path {
-   ⋮        segments: [
-   ⋮            PathSegment {
-   ⋮                ident: "list",
-   ⋮                arguments: None,
-   ⋮            },
-   ⋮        ],
-   ⋮    },
-   ⋮    nested: [
-   ⋮        Meta(Meta::NameValue {
-   ⋮            path: Path {
-   ⋮                segments: [
-   ⋮                    PathSegment {
-   ⋮                        ident: "name2",
-   ⋮                        arguments: None,
-   ⋮                    },
-   ⋮                ],
-   ⋮            },
-   ⋮            lit: 6,
-   ⋮        }),
-   ⋮    ],
-   ⋮})
+    Meta(Meta::List {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "list",
+                    arguments: None,
+                },
+            ],
+        },
+        nested: [
+            Meta(Meta::NameValue {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "name2",
+                            arguments: None,
+                        },
+                    ],
+                },
+                lit: 6,
+            }),
+        ],
+    })
     "###);
 }
diff --git a/third_party/rust/syn/tests/test_parse_buffer.rs b/third_party/rust/syn/tests/test_parse_buffer.rs
--- a/third_party/rust/syn/tests/test_parse_buffer.rs
+++ b/third_party/rust/syn/tests/test_parse_buffer.rs
@@ -1,12 +1,12 @@
-#[macro_use]
-extern crate syn;
-
+use proc_macro2::{Delimiter, Group, Punct, Spacing, TokenStream, TokenTree};
+use std::iter::FromIterator;
 use syn::parse::{discouraged::Speculative, Parse, ParseStream, Parser, Result};
+use syn::{parenthesized, Token};
 
 #[test]
 #[should_panic(expected = "Fork was not derived from the advancing parse stream")]
 fn smuggled_speculative_cursor_between_sources() {
     struct BreakRules;
     impl Parse for BreakRules {
         fn parse(input1: ParseStream) -> Result<Self> {
             let nested = |input2: ParseStream| {
@@ -48,8 +48,43 @@ fn smuggled_speculative_cursor_into_brac
             parenthesized!(a in input);
             input.advance_to(&a);
             Ok(Self)
         }
     }
 
     syn::parse_str::<BreakRules>("()").unwrap();
 }
+
+#[test]
+fn trailing_empty_none_group() {
+    fn parse(input: ParseStream) -> Result<()> {
+        input.parse::<Token![+]>()?;
+
+        let content;
+        parenthesized!(content in input);
+        content.parse::<Token![+]>()?;
+
+        Ok(())
+    }
+
+    // `+ ( + <Ø Ø> ) <Ø <Ø Ø> Ø>`
+    let tokens = TokenStream::from_iter(vec![
+        TokenTree::Punct(Punct::new('+', Spacing::Alone)),
+        TokenTree::Group(Group::new(
+            Delimiter::Parenthesis,
+            TokenStream::from_iter(vec![
+                TokenTree::Punct(Punct::new('+', Spacing::Alone)),
+                TokenTree::Group(Group::new(Delimiter::None, TokenStream::new())),
+            ]),
+        )),
+        TokenTree::Group(Group::new(Delimiter::None, TokenStream::new())),
+        TokenTree::Group(Group::new(
+            Delimiter::None,
+            TokenStream::from_iter(vec![TokenTree::Group(Group::new(
+                Delimiter::None,
+                TokenStream::new(),
+            ))]),
+        )),
+    ]);
+
+    parse.parse2(tokens).unwrap();
+}
diff --git a/third_party/rust/syn/tests/test_parse_stream.rs b/third_party/rust/syn/tests/test_parse_stream.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/tests/test_parse_stream.rs
@@ -0,0 +1,12 @@
+use syn::ext::IdentExt;
+use syn::parse::ParseStream;
+use syn::{Ident, Token};
+
+#[test]
+fn test_peek() {
+    let _ = |input: ParseStream| {
+        let _ = input.peek(Ident);
+        let _ = input.peek(Ident::peek_any);
+        let _ = input.peek(Token![::]);
+    };
+}
diff --git a/third_party/rust/syn/tests/test_pat.rs b/third_party/rust/syn/tests/test_pat.rs
--- a/third_party/rust/syn/tests/test_pat.rs
+++ b/third_party/rust/syn/tests/test_pat.rs
@@ -1,23 +1,38 @@
-extern crate quote;
-extern crate syn;
-
-mod features;
-
 use quote::quote;
-use syn::Pat;
+use syn::{Item, Pat, Stmt};
 
 #[test]
 fn test_pat_ident() {
     match syn::parse2(quote!(self)).unwrap() {
         Pat::Ident(_) => (),
         value => panic!("expected PatIdent, got {:?}", value),
     }
 }
 
 #[test]
 fn test_pat_path() {
     match syn::parse2(quote!(self::CONST)).unwrap() {
         Pat::Path(_) => (),
         value => panic!("expected PatPath, got {:?}", value),
     }
 }
+
+#[test]
+fn test_leading_vert() {
+    // https://github.com/rust-lang/rust/blob/1.43.0/src/test/ui/or-patterns/remove-leading-vert.rs
+
+    syn::parse_str::<Item>("fn f() {}").unwrap();
+    syn::parse_str::<Item>("fn fun1(| A: E) {}").unwrap_err();
+    syn::parse_str::<Item>("fn fun2(|| A: E) {}").unwrap_err();
+
+    syn::parse_str::<Stmt>("let | () = ();").unwrap();
+    syn::parse_str::<Stmt>("let (| A): E;").unwrap_err();
+    syn::parse_str::<Stmt>("let (|| A): (E);").unwrap_err();
+    syn::parse_str::<Stmt>("let (| A,): (E,);").unwrap_err();
+    syn::parse_str::<Stmt>("let [| A]: [E; 1];").unwrap_err();
+    syn::parse_str::<Stmt>("let [|| A]: [E; 1];").unwrap_err();
+    syn::parse_str::<Stmt>("let TS(| A): TS;").unwrap_err();
+    syn::parse_str::<Stmt>("let TS(|| A): TS;").unwrap_err();
+    syn::parse_str::<Stmt>("let NS { f: | A }: NS;").unwrap_err();
+    syn::parse_str::<Stmt>("let NS { f: || A }: NS;").unwrap_err();
+}
diff --git a/third_party/rust/syn/tests/test_path.rs b/third_party/rust/syn/tests/test_path.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/tests/test_path.rs
@@ -0,0 +1,52 @@
+#[macro_use]
+mod macros;
+
+use proc_macro2::{Delimiter, Group, Ident, Punct, Spacing, Span, TokenStream, TokenTree};
+use quote::quote;
+use std::iter::FromIterator;
+use syn::{Expr, Type};
+
+#[test]
+fn parse_interpolated_leading_component() {
+    // mimics the token stream corresponding to `$mod::rest`
+    let tokens = TokenStream::from_iter(vec![
+        TokenTree::Group(Group::new(Delimiter::None, quote! { first })),
+        TokenTree::Punct(Punct::new(':', Spacing::Joint)),
+        TokenTree::Punct(Punct::new(':', Spacing::Alone)),
+        TokenTree::Ident(Ident::new("rest", Span::call_site())),
+    ]);
+
+    snapshot!(tokens.clone() as Expr, @r###"
+    Expr::Path {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "first",
+                    arguments: None,
+                },
+                PathSegment {
+                    ident: "rest",
+                    arguments: None,
+                },
+            ],
+        },
+    }
+    "###);
+
+    snapshot!(tokens as Type, @r###"
+    Type::Path {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "first",
+                    arguments: None,
+                },
+                PathSegment {
+                    ident: "rest",
+                    arguments: None,
+                },
+            ],
+        },
+    }
+    "###);
+}
diff --git a/third_party/rust/syn/tests/test_precedence.rs b/third_party/rust/syn/tests/test_precedence.rs
--- a/third_party/rust/syn/tests/test_precedence.rs
+++ b/third_party/rust/syn/tests/test_precedence.rs
@@ -1,43 +1,34 @@
 #![cfg(not(syn_disable_nightly_tests))]
 #![recursion_limit = "1024"]
 #![feature(rustc_private)]
 
 //! The tests in this module do the following:
 //!
-//! 1. Parse a given expression in both `syn` and `libsyntax`.
+//! 1. Parse a given expression in both `syn` and `librustc`.
 //! 2. Fold over the expression adding brackets around each subexpression (with
-//!    some complications - see the `syn_brackets` and `libsyntax_brackets`
+//!    some complications - see the `syn_brackets` and `librustc_brackets`
 //!    methods).
 //! 3. Serialize the `syn` expression back into a string, and re-parse it with
-//!    `libsyntax`.
+//!    `librustc`.
 //! 4. Respan all of the expressions, replacing the spans with the default
 //!    spans.
 //! 5. Compare the expressions with one another, if they are not equal fail.
 
-extern crate quote;
-extern crate rayon;
-extern crate regex;
+extern crate rustc_ast;
 extern crate rustc_data_structures;
-extern crate smallvec;
-extern crate syn;
-extern crate syntax;
-extern crate syntax_pos;
-extern crate walkdir;
-
-mod features;
+extern crate rustc_span;
 
 use quote::quote;
 use rayon::iter::{IntoParallelIterator, ParallelIterator};
 use regex::Regex;
-use smallvec::smallvec;
-use syntax::ast;
-use syntax::ptr::P;
-use syntax_pos::edition::Edition;
+use rustc_ast::ast;
+use rustc_ast::ptr::P;
+use rustc_span::edition::Edition;
 use walkdir::{DirEntry, WalkDir};
 
 use std::fs::File;
 use std::io::Read;
 use std::process;
 use std::sync::atomic::{AtomicUsize, Ordering};
 
 use common::eq::SpanlessEq;
@@ -68,17 +59,17 @@ fn test_simple_precedence() {
     for input in EXPRS {
         let expr = if let Some(expr) = parse::syn_expr(input) {
             expr
         } else {
             failed += 1;
             continue;
         };
 
-        let pf = match test_expressions(vec![expr]) {
+        let pf = match test_expressions(Edition::Edition2018, vec![expr]) {
             (1, 0) => "passed",
             (0, 1) => {
                 failed += 1;
                 "failed"
             }
             _ => unreachable!(),
         };
         errorf!("=== {}: {}\n", input, pf);
@@ -86,18 +77,18 @@ fn test_simple_precedence() {
 
     if failed > 0 {
         panic!("Failed {} tests", failed);
     }
 }
 
 /// Test expressions from rustc, like in `test_round_trip`.
 #[test]
-#[cfg_attr(target_os = "windows", ignore = "requires nix .sh")]
 fn test_rustc_precedence() {
+    common::rayon_init();
     repo::clone_rust();
     let abort_after = common::abort_after();
     if abort_after == 0 {
         panic!("Skipping all precedence tests");
     }
 
     let passed = AtomicUsize::new(0);
     let failed = AtomicUsize::new(0);
@@ -113,34 +104,26 @@ fn test_rustc_precedence() {
         .unwrap()
         .into_par_iter()
         .for_each(|entry| {
             let path = entry.path();
             if path.is_dir() {
                 return;
             }
 
-            // Our version of `libsyntax` can't parse this tests
-            if path
-                .to_str()
-                .unwrap()
-                .ends_with("optional_comma_in_match_arm.rs")
-            {
-                return;
-            }
-
             let mut file = File::open(path).unwrap();
             let mut content = String::new();
             file.read_to_string(&mut content).unwrap();
             let content = edition_regex.replace_all(&content, "_$0");
 
             let (l_passed, l_failed) = match syn::parse_file(&content) {
                 Ok(file) => {
+                    let edition = repo::edition(path).parse().unwrap();
                     let exprs = collect_exprs(file);
-                    test_expressions(exprs)
+                    test_expressions(edition, exprs)
                 }
                 Err(msg) => {
                     errorf!("syn failed to parse\n{:?}\n", msg);
                     (0, 1)
                 }
             };
 
             errorf!(
@@ -164,147 +147,182 @@ fn test_rustc_precedence() {
     errorf!("\n===== Precedence Test Results =====\n");
     errorf!("{} passed | {} failed\n", passed, failed);
 
     if failed > 0 {
         panic!("{} failures", failed);
     }
 }
 
-fn test_expressions(exprs: Vec<syn::Expr>) -> (usize, usize) {
+fn test_expressions(edition: Edition, exprs: Vec<syn::Expr>) -> (usize, usize) {
     let mut passed = 0;
     let mut failed = 0;
 
-    syntax::with_globals(Edition::Edition2018, || {
+    rustc_span::with_session_globals(edition, || {
         for expr in exprs {
             let raw = quote!(#expr).to_string();
 
-            let libsyntax_ast = if let Some(e) = libsyntax_parse_and_rewrite(&raw) {
+            let librustc_ast = if let Some(e) = librustc_parse_and_rewrite(&raw) {
                 e
             } else {
                 failed += 1;
-                errorf!("\nFAIL - libsyntax failed to parse raw\n");
+                errorf!("\nFAIL - librustc failed to parse raw\n");
                 continue;
             };
 
             let syn_expr = syn_brackets(expr);
-            let syn_ast = if let Some(e) = parse::libsyntax_expr(&quote!(#syn_expr).to_string()) {
+            let syn_ast = if let Some(e) = parse::librustc_expr(&quote!(#syn_expr).to_string()) {
                 e
             } else {
                 failed += 1;
-                errorf!("\nFAIL - libsyntax failed to parse bracketed\n");
+                errorf!("\nFAIL - librustc failed to parse bracketed\n");
                 continue;
             };
 
-            if SpanlessEq::eq(&syn_ast, &libsyntax_ast) {
+            if SpanlessEq::eq(&syn_ast, &librustc_ast) {
                 passed += 1;
             } else {
                 failed += 1;
-                errorf!("\nFAIL\n{:?}\n!=\n{:?}\n", syn_ast, libsyntax_ast);
+                errorf!("\nFAIL\n{:?}\n!=\n{:?}\n", syn_ast, librustc_ast);
             }
         }
     });
 
     (passed, failed)
 }
 
-fn libsyntax_parse_and_rewrite(input: &str) -> Option<P<ast::Expr>> {
-    parse::libsyntax_expr(input).and_then(libsyntax_brackets)
+fn librustc_parse_and_rewrite(input: &str) -> Option<P<ast::Expr>> {
+    parse::librustc_expr(input).and_then(librustc_brackets)
 }
 
 /// Wrap every expression which is not already wrapped in parens with parens, to
 /// reveal the precidence of the parsed expressions, and produce a stringified
 /// form of the resulting expression.
 ///
-/// This method operates on libsyntax objects.
-fn libsyntax_brackets(mut libsyntax_expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
+/// This method operates on librustc objects.
+fn librustc_brackets(mut librustc_expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
+    use rustc_ast::ast::{
+        Block, BorrowKind, Expr, ExprKind, Field, GenericArg, MacCall, Pat, Stmt, StmtKind, Ty,
+    };
+    use rustc_ast::mut_visit::{noop_visit_generic_arg, MutVisitor};
+    use rustc_data_structures::map_in_place::MapInPlace;
     use rustc_data_structures::thin_vec::ThinVec;
-    use smallvec::SmallVec;
+    use rustc_span::DUMMY_SP;
     use std::mem;
-    use syntax::ast::{Expr, ExprKind, Field, Mac, Pat, Stmt, StmtKind, Ty};
-    use syntax::mut_visit::{noop_visit_expr, MutVisitor};
-    use syntax_pos::DUMMY_SP;
 
     struct BracketsVisitor {
         failed: bool,
     };
 
+    fn flat_map_field<T: MutVisitor>(mut f: Field, vis: &mut T) -> Vec<Field> {
+        if f.is_shorthand {
+            noop_visit_expr(&mut f.expr, vis);
+        } else {
+            vis.visit_expr(&mut f.expr);
+        }
+        vec![f]
+    }
+
+    fn flat_map_stmt<T: MutVisitor>(stmt: Stmt, vis: &mut T) -> Vec<Stmt> {
+        let kind = match stmt.kind {
+            // Don't wrap toplevel expressions in statements.
+            StmtKind::Expr(mut e) => {
+                noop_visit_expr(&mut e, vis);
+                StmtKind::Expr(e)
+            }
+            StmtKind::Semi(mut e) => {
+                noop_visit_expr(&mut e, vis);
+                StmtKind::Semi(e)
+            }
+            s => s,
+        };
+
+        vec![Stmt { kind, ..stmt }]
+    }
+
+    fn noop_visit_expr<T: MutVisitor>(e: &mut Expr, vis: &mut T) {
+        use rustc_ast::mut_visit::{noop_visit_expr, visit_opt, visit_thin_attrs};
+        match &mut e.kind {
+            ExprKind::AddrOf(BorrowKind::Raw, ..) => {}
+            ExprKind::Struct(path, fields, expr) => {
+                vis.visit_path(path);
+                fields.flat_map_in_place(|field| flat_map_field(field, vis));
+                visit_opt(expr, |expr| vis.visit_expr(expr));
+                vis.visit_id(&mut e.id);
+                vis.visit_span(&mut e.span);
+                visit_thin_attrs(&mut e.attrs, vis);
+            }
+            _ => noop_visit_expr(e, vis),
+        }
+    }
+
     impl MutVisitor for BracketsVisitor {
         fn visit_expr(&mut self, e: &mut P<Expr>) {
             noop_visit_expr(e, self);
-            match e.node {
+            match e.kind {
                 ExprKind::If(..) | ExprKind::Block(..) | ExprKind::Let(..) => {}
                 _ => {
                     let inner = mem::replace(
                         e,
                         P(Expr {
                             id: ast::DUMMY_NODE_ID,
-                            node: ExprKind::Err,
+                            kind: ExprKind::Err,
                             span: DUMMY_SP,
                             attrs: ThinVec::new(),
+                            tokens: None,
                         }),
                     );
-                    e.node = ExprKind::Paren(inner);
+                    e.kind = ExprKind::Paren(inner);
                 }
             }
         }
 
-        fn flat_map_field(&mut self, mut f: Field) -> SmallVec<[Field; 1]> {
-            if f.is_shorthand {
-                noop_visit_expr(&mut f.expr, self);
-            } else {
-                self.visit_expr(&mut f.expr);
+        fn visit_generic_arg(&mut self, arg: &mut GenericArg) {
+            match arg {
+                // Don't wrap const generic arg as that's invalid syntax.
+                GenericArg::Const(arg) => noop_visit_expr(&mut arg.value, self),
+                _ => noop_visit_generic_arg(arg, self),
             }
-            SmallVec::from([f])
+        }
+
+        fn visit_block(&mut self, block: &mut P<Block>) {
+            self.visit_id(&mut block.id);
+            block
+                .stmts
+                .flat_map_in_place(|stmt| flat_map_stmt(stmt, self));
+            self.visit_span(&mut block.span);
         }
 
         // We don't want to look at expressions that might appear in patterns or
         // types yet. We'll look into comparing those in the future. For now
         // focus on expressions appearing in other places.
         fn visit_pat(&mut self, pat: &mut P<Pat>) {
             let _ = pat;
         }
 
         fn visit_ty(&mut self, ty: &mut P<Ty>) {
             let _ = ty;
         }
 
-        fn flat_map_stmt(&mut self, stmt: Stmt) -> SmallVec<[Stmt; 1]> {
-            let node = match stmt.node {
-                // Don't wrap toplevel expressions in statements.
-                StmtKind::Expr(mut e) => {
-                    noop_visit_expr(&mut e, self);
-                    StmtKind::Expr(e)
-                }
-                StmtKind::Semi(mut e) => {
-                    noop_visit_expr(&mut e, self);
-                    StmtKind::Semi(e)
-                }
-                s => s,
-            };
-
-            smallvec![Stmt { node, ..stmt }]
-        }
-
-        fn visit_mac(&mut self, mac: &mut Mac) {
-            // By default when folding over macros, libsyntax panics. This is
+        fn visit_mac(&mut self, mac: &mut MacCall) {
+            // By default when folding over macros, librustc panics. This is
             // because it's usually not what you want, you want to run after
             // macro expansion. We do want to do that (syn doesn't do macro
             // expansion), so we implement visit_mac to just return the macro
             // unchanged.
             let _ = mac;
         }
     }
 
     let mut folder = BracketsVisitor { failed: false };
-    folder.visit_expr(&mut libsyntax_expr);
+    folder.visit_expr(&mut librustc_expr);
     if folder.failed {
         None
     } else {
-        Some(libsyntax_expr)
+        Some(librustc_expr)
     }
 }
 
 /// Wrap every expression which is not already wrapped in parens with parens, to
 /// reveal the precedence of the parsed expressions, and produce a stringified
 /// form of the resulting expression.
 fn syn_brackets(syn_expr: syn::Expr) -> syn::Expr {
     use syn::fold::*;
@@ -313,24 +331,43 @@ fn syn_brackets(syn_expr: syn::Expr) -> 
     struct ParenthesizeEveryExpr;
     impl Fold for ParenthesizeEveryExpr {
         fn fold_expr(&mut self, expr: Expr) -> Expr {
             match expr {
                 Expr::Group(_) => unreachable!(),
                 Expr::If(..) | Expr::Unsafe(..) | Expr::Block(..) | Expr::Let(..) => {
                     fold_expr(self, expr)
                 }
-                node => Expr::Paren(ExprParen {
+                _ => Expr::Paren(ExprParen {
                     attrs: Vec::new(),
-                    expr: Box::new(fold_expr(self, node)),
+                    expr: Box::new(fold_expr(self, expr)),
                     paren_token: token::Paren::default(),
                 }),
             }
         }
 
+        fn fold_generic_argument(&mut self, arg: GenericArgument) -> GenericArgument {
+            match arg {
+                // Don't wrap const generic arg as that's invalid syntax.
+                GenericArgument::Const(a) => GenericArgument::Const(fold_expr(self, a)),
+                _ => fold_generic_argument(self, arg),
+            }
+        }
+
+        fn fold_generic_method_argument(
+            &mut self,
+            arg: GenericMethodArgument,
+        ) -> GenericMethodArgument {
+            match arg {
+                // Don't wrap const generic arg as that's invalid syntax.
+                GenericMethodArgument::Const(a) => GenericMethodArgument::Const(fold_expr(self, a)),
+                _ => fold_generic_method_argument(self, arg),
+            }
+        }
+
         fn fold_stmt(&mut self, stmt: Stmt) -> Stmt {
             match stmt {
                 // Don't wrap toplevel expressions in statements.
                 Stmt::Expr(e) => Stmt::Expr(fold_expr(self, e)),
                 Stmt::Semi(e, semi) => Stmt::Semi(fold_expr(self, e), semi),
                 s => s,
             }
         }
@@ -355,17 +392,20 @@ fn syn_brackets(syn_expr: syn::Expr) -> 
 fn collect_exprs(file: syn::File) -> Vec<syn::Expr> {
     use syn::fold::*;
     use syn::punctuated::Punctuated;
     use syn::*;
 
     struct CollectExprs(Vec<Expr>);
     impl Fold for CollectExprs {
         fn fold_expr(&mut self, expr: Expr) -> Expr {
-            self.0.push(expr);
+            match expr {
+                Expr::Verbatim(tokens) if tokens.is_empty() => {}
+                _ => self.0.push(expr),
+            }
 
             Expr::Tuple(ExprTuple {
                 attrs: vec![],
                 elems: Punctuated::new(),
                 paren_token: token::Paren::default(),
             })
         }
     }
diff --git a/third_party/rust/syn/tests/test_receiver.rs b/third_party/rust/syn/tests/test_receiver.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/tests/test_receiver.rs
@@ -0,0 +1,127 @@
+use syn::{parse_quote, FnArg, Receiver, TraitItemMethod};
+
+#[test]
+fn test_by_value() {
+    let TraitItemMethod { sig, .. } = parse_quote! {
+        fn by_value(self: Self);
+    };
+    match sig.receiver() {
+        Some(FnArg::Typed(_)) => (),
+        value => panic!("expected FnArg::Typed, got {:?}", value),
+    }
+}
+
+#[test]
+fn test_by_mut_value() {
+    let TraitItemMethod { sig, .. } = parse_quote! {
+        fn by_mut(mut self: Self);
+    };
+    match sig.receiver() {
+        Some(FnArg::Typed(_)) => (),
+        value => panic!("expected FnArg::Typed, got {:?}", value),
+    }
+}
+
+#[test]
+fn test_by_ref() {
+    let TraitItemMethod { sig, .. } = parse_quote! {
+        fn by_ref(self: &Self);
+    };
+    match sig.receiver() {
+        Some(FnArg::Typed(_)) => (),
+        value => panic!("expected FnArg::Typed, got {:?}", value),
+    }
+}
+
+#[test]
+fn test_by_box() {
+    let TraitItemMethod { sig, .. } = parse_quote! {
+        fn by_box(self: Box<Self>);
+    };
+    match sig.receiver() {
+        Some(FnArg::Typed(_)) => (),
+        value => panic!("expected FnArg::Typed, got {:?}", value),
+    }
+}
+
+#[test]
+fn test_by_pin() {
+    let TraitItemMethod { sig, .. } = parse_quote! {
+        fn by_pin(self: Pin<Self>);
+    };
+    match sig.receiver() {
+        Some(FnArg::Typed(_)) => (),
+        value => panic!("expected FnArg::Typed, got {:?}", value),
+    }
+}
+
+#[test]
+fn test_explicit_type() {
+    let TraitItemMethod { sig, .. } = parse_quote! {
+        fn explicit_type(self: Pin<MyType>);
+    };
+    match sig.receiver() {
+        Some(FnArg::Typed(_)) => (),
+        value => panic!("expected FnArg::Typed, got {:?}", value),
+    }
+}
+
+#[test]
+fn test_value_shorthand() {
+    let TraitItemMethod { sig, .. } = parse_quote! {
+        fn value_shorthand(self);
+    };
+    match sig.receiver() {
+        Some(FnArg::Receiver(Receiver {
+            reference: None,
+            mutability: None,
+            ..
+        })) => (),
+        value => panic!("expected FnArg::Receiver without ref/mut, got {:?}", value),
+    }
+}
+
+#[test]
+fn test_mut_value_shorthand() {
+    let TraitItemMethod { sig, .. } = parse_quote! {
+        fn mut_value_shorthand(mut self);
+    };
+    match sig.receiver() {
+        Some(FnArg::Receiver(Receiver {
+            reference: None,
+            mutability: Some(_),
+            ..
+        })) => (),
+        value => panic!("expected FnArg::Receiver with mut, got {:?}", value),
+    }
+}
+
+#[test]
+fn test_ref_shorthand() {
+    let TraitItemMethod { sig, .. } = parse_quote! {
+        fn ref_shorthand(&self);
+    };
+    match sig.receiver() {
+        Some(FnArg::Receiver(Receiver {
+            reference: Some(_),
+            mutability: None,
+            ..
+        })) => (),
+        value => panic!("expected FnArg::Receiver with ref, got {:?}", value),
+    }
+}
+
+#[test]
+fn test_ref_mut_shorthand() {
+    let TraitItemMethod { sig, .. } = parse_quote! {
+        fn ref_mut_shorthand(&mut self);
+    };
+    match sig.receiver() {
+        Some(FnArg::Receiver(Receiver {
+            reference: Some(_),
+            mutability: Some(_),
+            ..
+        })) => (),
+        value => panic!("expected FnArg::Receiver with ref+mut, got {:?}", value),
+    }
+}
diff --git a/third_party/rust/syn/tests/test_round_trip.rs b/third_party/rust/syn/tests/test_round_trip.rs
--- a/third_party/rust/syn/tests/test_round_trip.rs
+++ b/third_party/rust/syn/tests/test_round_trip.rs
@@ -1,28 +1,26 @@
 #![cfg(not(syn_disable_nightly_tests))]
 #![recursion_limit = "1024"]
 #![feature(rustc_private)]
 
-extern crate quote;
-extern crate rayon;
-extern crate syn;
-extern crate syntax;
-extern crate syntax_pos;
-extern crate walkdir;
-
-mod features;
+extern crate rustc_ast;
+extern crate rustc_errors;
+extern crate rustc_expand;
+extern crate rustc_parse as parse;
+extern crate rustc_session;
+extern crate rustc_span;
 
 use quote::quote;
 use rayon::iter::{IntoParallelIterator, ParallelIterator};
-use syntax::ast;
-use syntax::parse::{self, PResult, ParseSess};
-use syntax::source_map::FilePathMapping;
-use syntax_pos::edition::Edition;
-use syntax_pos::FileName;
+use rustc_ast::ast;
+use rustc_errors::PResult;
+use rustc_session::parse::ParseSess;
+use rustc_span::source_map::FilePathMapping;
+use rustc_span::FileName;
 use walkdir::{DirEntry, WalkDir};
 
 use std::fs::File;
 use std::io::Read;
 use std::panic;
 use std::process;
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::time::Instant;
@@ -33,18 +31,18 @@ mod macros;
 #[allow(dead_code)]
 mod common;
 
 mod repo;
 
 use common::eq::SpanlessEq;
 
 #[test]
-#[cfg_attr(target_os = "windows", ignore = "requires nix .sh")]
 fn test_round_trip() {
+    common::rayon_init();
     repo::clone_rust();
     let abort_after = common::abort_after();
     if abort_after == 0 {
         panic!("Skipping all round_trip tests");
     }
 
     let failed = AtomicUsize::new(0);
 
@@ -73,43 +71,44 @@ fn test_round_trip() {
                     let prev_failed = failed.fetch_add(1, Ordering::SeqCst);
                     if prev_failed + 1 >= abort_after {
                         process::exit(1);
                     }
                     return;
                 }
             };
             let back = quote!(#krate).to_string();
+            let edition = repo::edition(path).parse().unwrap();
 
             let equal = panic::catch_unwind(|| {
-                syntax::with_globals(Edition::Edition2018, || {
+                rustc_span::with_session_globals(edition, || {
                     let sess = ParseSess::new(FilePathMapping::empty());
-                    let before = match libsyntax_parse(content, &sess) {
+                    let before = match librustc_parse(content, &sess) {
                         Ok(before) => before,
                         Err(mut diagnostic) => {
                             diagnostic.cancel();
                             if diagnostic
                                 .message()
                                 .starts_with("file not found for module")
                             {
                                 errorf!("=== {}: ignore\n", path.display());
                             } else {
                                 errorf!(
-                                "=== {}: ignore - libsyntax failed to parse original content: {}\n",
+                                "=== {}: ignore - librustc failed to parse original content: {}\n",
                                 path.display(),
                                 diagnostic.message()
                             );
                             }
                             return true;
                         }
                     };
-                    let after = match libsyntax_parse(back, &sess) {
+                    let after = match librustc_parse(back, &sess) {
                         Ok(after) => after,
                         Err(mut diagnostic) => {
-                            errorf!("=== {}: libsyntax failed to parse", path.display());
+                            errorf!("=== {}: librustc failed to parse", path.display());
                             diagnostic.emit();
                             return false;
                         }
                     };
 
                     if SpanlessEq::eq(&before, &after) {
                         errorf!(
                             "=== {}: pass in {}ms\n",
@@ -125,29 +124,29 @@ fn test_round_trip() {
                             before,
                             after,
                         );
                         false
                     }
                 })
             });
             match equal {
-                Err(_) => errorf!("=== {}: ignoring libsyntax panic\n", path.display()),
+                Err(_) => errorf!("=== {}: ignoring librustc panic\n", path.display()),
                 Ok(true) => {}
                 Ok(false) => {
                     let prev_failed = failed.fetch_add(1, Ordering::SeqCst);
                     if prev_failed + 1 >= abort_after {
                         process::exit(1);
                     }
                 }
             }
         });
 
     let failed = failed.load(Ordering::SeqCst);
     if failed > 0 {
         panic!("{} failures", failed);
     }
 }
 
-fn libsyntax_parse(content: String, sess: &ParseSess) -> PResult<ast::Crate> {
+fn librustc_parse(content: String, sess: &ParseSess) -> PResult<ast::Crate> {
     let name = FileName::Custom("test_round_trip".to_string());
     parse::parse_crate_from_source_str(name, content, sess)
 }
diff --git a/third_party/rust/syn/tests/test_shebang.rs b/third_party/rust/syn/tests/test_shebang.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/tests/test_shebang.rs
@@ -0,0 +1,59 @@
+#[macro_use]
+mod macros;
+
+#[test]
+fn test_basic() {
+    let content = "#!/usr/bin/env rustx\nfn main() {}";
+    let file = syn::parse_file(content).unwrap();
+    snapshot!(file, @r###"
+    File {
+        shebang: Some("#!/usr/bin/env rustx"),
+        items: [
+            Item::Fn {
+                vis: Inherited,
+                sig: Signature {
+                    ident: "main",
+                    generics: Generics,
+                    output: Default,
+                },
+                block: Block,
+            },
+        ],
+    }
+    "###);
+}
+
+#[test]
+fn test_comment() {
+    let content = "#!//am/i/a/comment\n[allow(dead_code)] fn main() {}";
+    let file = syn::parse_file(content).unwrap();
+    snapshot!(file, @r###"
+    File {
+        attrs: [
+            Attribute {
+                style: Inner,
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "allow",
+                            arguments: None,
+                        },
+                    ],
+                },
+                tokens: TokenStream(`(dead_code)`),
+            },
+        ],
+        items: [
+            Item::Fn {
+                vis: Inherited,
+                sig: Signature {
+                    ident: "main",
+                    generics: Generics,
+                    output: Default,
+                },
+                block: Block,
+            },
+        ],
+    }
+    "###);
+}
diff --git a/third_party/rust/syn/tests/test_should_parse.rs b/third_party/rust/syn/tests/test_should_parse.rs
--- a/third_party/rust/syn/tests/test_should_parse.rs
+++ b/third_party/rust/syn/tests/test_should_parse.rs
@@ -1,12 +1,8 @@
-extern crate syn;
-
-mod features;
-
 macro_rules! should_parse {
     ($name:ident, { $($in:tt)* }) => {
         #[test]
         fn $name() {
             // Make sure we can parse the file!
             syn::parse_file(stringify!($($in)*)).unwrap();
         }
     }
diff --git a/third_party/rust/syn/tests/test_size.rs b/third_party/rust/syn/tests/test_size.rs
--- a/third_party/rust/syn/tests/test_size.rs
+++ b/third_party/rust/syn/tests/test_size.rs
@@ -1,12 +1,10 @@
 #![cfg(target_pointer_width = "64")]
 
-mod features;
-
 use std::mem;
 use syn::*;
 
 #[test]
 fn test_expr_size() {
     assert_eq!(mem::size_of::<Expr>(), 280);
 }
 
diff --git a/third_party/rust/syn/tests/test_stmt.rs b/third_party/rust/syn/tests/test_stmt.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/tests/test_stmt.rs
@@ -0,0 +1,44 @@
+#[macro_use]
+mod macros;
+
+use syn::Stmt;
+
+#[test]
+fn test_raw_operator() {
+    let stmt = syn::parse_str::<Stmt>("let _ = &raw const x;").unwrap();
+
+    snapshot!(stmt, @r###"
+    Local(Local {
+        pat: Pat::Wild,
+        init: Some(Verbatim(`& raw const x`)),
+    })
+    "###);
+}
+
+#[test]
+fn test_raw_variable() {
+    let stmt = syn::parse_str::<Stmt>("let _ = &raw;").unwrap();
+
+    snapshot!(stmt, @r###"
+    Local(Local {
+        pat: Pat::Wild,
+        init: Some(Expr::Reference {
+            expr: Expr::Path {
+                path: Path {
+                    segments: [
+                        PathSegment {
+                            ident: "raw",
+                            arguments: None,
+                        },
+                    ],
+                },
+            },
+        }),
+    })
+    "###);
+}
+
+#[test]
+fn test_raw_invalid() {
+    assert!(syn::parse_str::<Stmt>("let _ = &raw x;").is_err());
+}
diff --git a/third_party/rust/syn/tests/test_token_trees.rs b/third_party/rust/syn/tests/test_token_trees.rs
--- a/third_party/rust/syn/tests/test_token_trees.rs
+++ b/third_party/rust/syn/tests/test_token_trees.rs
@@ -1,14 +1,8 @@
-extern crate proc_macro2;
-extern crate quote;
-extern crate syn;
-
-mod features;
-
 #[macro_use]
 mod macros;
 
 use proc_macro2::TokenStream;
 use quote::quote;
 use syn::Lit;
 
 #[test]
@@ -16,17 +10,21 @@ fn test_struct() {
     let input = "
         #[derive(Debug, Clone)]
         pub struct Item {
             pub ident: Ident,
             pub attrs: Vec<Attribute>,
         }
     ";
 
-    snapshot!(input as TokenStream, @"`# [ derive ( Debug , Clone ) ] pub struct Item { pub ident : Ident , pub attrs : Vec < Attribute >, }`");
+    snapshot!(input as TokenStream, @r###"
+    TokenStream(
+        `# [derive (Debug , Clone)] pub struct Item { pub ident : Ident , pub attrs : Vec < Attribute >, }`,
+    )
+    "###);
 }
 
 #[test]
 fn test_literal_mangling() {
     let code = "0_4";
     let parsed: Lit = syn::parse_str(code).unwrap();
     assert_eq!(code, quote!(#parsed).to_string());
 }
diff --git a/third_party/rust/syn/tests/test_ty.rs b/third_party/rust/syn/tests/test_ty.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/tests/test_ty.rs
@@ -0,0 +1,53 @@
+#[macro_use]
+mod macros;
+
+use proc_macro2::{Delimiter, Group, Ident, Punct, Spacing, Span, TokenStream, TokenTree};
+use quote::quote;
+use std::iter::FromIterator;
+use syn::Type;
+
+#[test]
+fn test_mut_self() {
+    syn::parse_str::<Type>("fn(mut self)").unwrap();
+    syn::parse_str::<Type>("fn(mut self: ())").unwrap();
+    syn::parse_str::<Type>("fn(mut self: ...)").unwrap_err();
+    syn::parse_str::<Type>("fn(mut self: mut self)").unwrap_err();
+    syn::parse_str::<Type>("fn(mut self::T)").unwrap_err();
+}
+
+#[test]
+fn test_macro_variable_type() {
+    // mimics the token stream corresponding to `$ty<T>`
+    let tokens = TokenStream::from_iter(vec![
+        TokenTree::Group(Group::new(Delimiter::None, quote! { ty })),
+        TokenTree::Punct(Punct::new('<', Spacing::Alone)),
+        TokenTree::Ident(Ident::new("T", Span::call_site())),
+        TokenTree::Punct(Punct::new('>', Spacing::Alone)),
+    ]);
+
+    snapshot!(tokens as Type, @r###"
+    Type::Path {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "ty",
+                    arguments: PathArguments::AngleBracketed {
+                        args: [
+                            Type(Type::Path {
+                                path: Path {
+                                    segments: [
+                                        PathSegment {
+                                            ident: "T",
+                                            arguments: None,
+                                        },
+                                    ],
+                                },
+                            }),
+                        ],
+                    },
+                },
+            ],
+        },
+    }
+    "###);
+}
diff --git a/third_party/rust/syn/tests/test_visibility.rs b/third_party/rust/syn/tests/test_visibility.rs
new file mode 100644
--- /dev/null
+++ b/third_party/rust/syn/tests/test_visibility.rs
@@ -0,0 +1,145 @@
+#[macro_use]
+mod macros;
+
+use proc_macro2::{Delimiter, Group, Ident, Punct, Spacing, Span, TokenStream, TokenTree};
+use std::iter::FromIterator;
+use syn::parse::{Parse, ParseStream};
+use syn::{DeriveInput, Result, Visibility};
+
+#[derive(Debug)]
+struct VisRest {
+    vis: Visibility,
+    rest: TokenStream,
+}
+
+impl Parse for VisRest {
+    fn parse(input: ParseStream) -> Result<Self> {
+        Ok(VisRest {
+            vis: input.parse()?,
+            rest: input.parse()?,
+        })
+    }
+}
+
+macro_rules! assert_vis_parse {
+    ($input:expr, Ok($p:pat)) => {
+        assert_vis_parse!($input, Ok($p) + "");
+    };
+
+    ($input:expr, Ok($p:pat) + $rest:expr) => {
+        let expected = $rest.parse::<TokenStream>().unwrap();
+        let parse: VisRest = syn::parse_str($input).unwrap();
+
+        match parse.vis {
+            $p => {}
+            _ => panic!("Expected {}, got {:?}", stringify!($p), parse.vis),
+        }
+
+        // NOTE: Round-trips through `to_string` to avoid potential whitespace
+        // diffs.
+        assert_eq!(parse.rest.to_string(), expected.to_string());
+    };
+
+    ($input:expr, Err) => {
+        syn::parse2::<VisRest>($input.parse().unwrap()).unwrap_err();
+    };
+}
+
+#[test]
+fn test_pub() {
+    assert_vis_parse!("pub", Ok(Visibility::Public(_)));
+}
+
+#[test]
+fn test_crate() {
+    assert_vis_parse!("crate", Ok(Visibility::Crate(_)));
+}
+
+#[test]
+fn test_inherited() {
+    assert_vis_parse!("", Ok(Visibility::Inherited));
+}
+
+#[test]
+fn test_in() {
+    assert_vis_parse!("pub(in foo::bar)", Ok(Visibility::Restricted(_)));
+}
+
+#[test]
+fn test_pub_crate() {
+    assert_vis_parse!("pub(crate)", Ok(Visibility::Restricted(_)));
+}
+
+#[test]
+fn test_pub_self() {
+    assert_vis_parse!("pub(self)", Ok(Visibility::Restricted(_)));
+}
+
+#[test]
+fn test_pub_super() {
+    assert_vis_parse!("pub(super)", Ok(Visibility::Restricted(_)));
+}
+
+#[test]
+fn test_missing_in() {
+    assert_vis_parse!("pub(foo::bar)", Ok(Visibility::Public(_)) + "(foo::bar)");
+}
+
+#[test]
+fn test_missing_in_path() {
+    assert_vis_parse!("pub(in)", Err);
+}
+
+#[test]
+fn test_crate_path() {
+    assert_vis_parse!("pub(crate::A, crate::B)", Ok(Visibility::Public(_)) + "(crate::A, crate::B)");
+}
+
+#[test]
+fn test_junk_after_in() {
+    assert_vis_parse!("pub(in some::path @@garbage)", Err);
+}
+
+#[test]
+fn test_empty_group_vis() {
+    // mimics `struct S { $vis $field: () }` where $vis is empty
+    let tokens = TokenStream::from_iter(vec![
+        TokenTree::Ident(Ident::new("struct", Span::call_site())),
+        TokenTree::Ident(Ident::new("S", Span::call_site())),
+        TokenTree::Group(Group::new(
+            Delimiter::Brace,
+            TokenStream::from_iter(vec![
+                TokenTree::Group(Group::new(Delimiter::None, TokenStream::new())),
+                TokenTree::Group(Group::new(
+                    Delimiter::None,
+                    TokenStream::from_iter(vec![TokenTree::Ident(Ident::new(
+                        "f",
+                        Span::call_site(),
+                    ))]),
+                )),
+                TokenTree::Punct(Punct::new(':', Spacing::Alone)),
+                TokenTree::Group(Group::new(Delimiter::Parenthesis, TokenStream::new())),
+            ]),
+        )),
+    ]);
+
+    snapshot!(tokens as DeriveInput, @r###"
+    DeriveInput {
+        vis: Inherited,
+        ident: "S",
+        generics: Generics,
+        data: Data::Struct {
+            fields: Fields::Named {
+                named: [
+                    Field {
+                        vis: Inherited,
+                        ident: Some("f"),
+                        colon_token: Some,
+                        ty: Type::Tuple,
+                    },
+                ],
+            },
+        },
+    }
+    "###);
+}
diff --git a/third_party/rust/syn/tests/zzz_stable.rs b/third_party/rust/syn/tests/zzz_stable.rs
--- a/third_party/rust/syn/tests/zzz_stable.rs
+++ b/third_party/rust/syn/tests/zzz_stable.rs
@@ -1,21 +1,19 @@
 #![cfg(syn_disable_nightly_tests)]
 
-extern crate termcolor;
-
 use std::io::{self, Write};
 use termcolor::{Color, ColorChoice, ColorSpec, StandardStream, WriteColor};
 
 const MSG: &str = "\
 ‖
 ‖   WARNING:
 ‖   This is not a nightly compiler so not all tests were able to
 ‖   run. Syn includes tests that compare Syn's parser against the
-‖   compiler's parser, which requires access to unstable libsyntax
+‖   compiler's parser, which requires access to unstable librustc
 ‖   data structures and a nightly compiler.
 ‖
 ";
 
 #[test]
 fn notice() -> io::Result<()> {
     let header = "WARNING";
     let index_of_header = MSG.find(header).unwrap();