diff -urN -X ./diff-exclude flex-2.5.31/flex.skl flex/flex.skl
--- flex-2.5.31/flex.skl	2003-04-01 04:51:38.000000000 +0300
+++ flex/flex.skl	2004-01-02 12:22:33.000000000 +0200
@@ -27,6 +27,13 @@
 %# Macros for runtime processing stage.
 m4_changecom
 m4_changequote
+
+%# Support for m4 quote escaping
+m4_changequote({, })
+m4_define( {m4_userquote_start}, {m4_changequote(<, >)[[m4_changequote([[, ]])})
+m4_define( {m4_userquote_end}, {m4_changequote(<, >)]]m4_changequote([[, ]])})
+
+%# Setup quoting
 m4_changequote([[, ]])
 
 %# 
diff -urN -X ./diff-exclude flex-2.5.31/flexdef.h flex/flexdef.h
--- flex-2.5.31/flexdef.h	2003-04-01 04:51:38.000000000 +0300
+++ flex/flexdef.h	2004-01-02 12:14:49.000000000 +0200
@@ -373,6 +373,7 @@
  * yymore_really_used - whether to treat yymore() as really used, regardless
  *   of what we think based on references to it in the user's actions.
  * reject_really_used - same for REJECT
+ * keep_m4 - dont quote m4 quotes "[[", "]]" - so user can use m4
  */
 
 extern int printstats, syntaxerror, eofseen, ddebug, trace, nowarn,
@@ -387,7 +388,7 @@
 extern int yymore_used, reject, real_reject, continued_action, in_rule;
 
 extern int yymore_really_used, reject_really_used;
-
+extern int keep_m4;
 
 /* Variables used in the flex input routines:
  * datapos - characters on current output line
diff -urN -X ./diff-exclude flex-2.5.31/main.c flex/main.c
--- flex-2.5.31/main.c	2003-04-01 04:51:38.000000000 +0300
+++ flex/main.c	2004-01-02 12:13:07.000000000 +0200
@@ -106,6 +106,7 @@
 bool   *rule_has_nl, *ccl_has_nl;
 int     nlch = '\n';
 bool    ansi_func_defs, ansi_func_protos;
+int	keep_m4;
 
 bool    tablesext, tablesverify, gentables;
 char   *tablesfilename=0,*tablesname=0;
@@ -999,6 +1000,10 @@
 		case OPT_DONOTHING:
 			break;
 
+		case OPT_KEEP_M4:
+			keep_m4 = true;
+			break;
+
 		case OPT_COMPRESSION:
 			if (!sawcmpflag) {
 				useecs = false;
diff -urN -X ./diff-exclude flex-2.5.31/options.c flex/options.c
--- flex-2.5.31/options.c	2003-03-25 18:39:08.000000000 +0200
+++ flex/options.c	2004-01-02 12:16:07.000000000 +0200
@@ -42,6 +42,10 @@
 /* The command-line options, passed to scanopt_init() */
 optspec_t flexopts[] = {
 
+	{"-4", OPT_KEEP_M4, 0}
+	,
+	{"--keep-m4", OPT_KEEP_M4, 0}
+	,			/* dont try to quote m4 */
 	{"-7", OPT_7BIT, 0}
 	,
 	{"--7bit", OPT_7BIT, 0}
diff -urN -X ./diff-exclude flex-2.5.31/options.h flex/options.h
--- flex-2.5.31/options.h	2003-03-25 18:39:08.000000000 +0200
+++ flex/options.h	2004-01-02 12:15:30.000000000 +0200
@@ -61,6 +61,7 @@
 	OPT_HEADER_FILE,
 	OPT_HELP,
 	OPT_INTERACTIVE,
+	OPT_KEEP_M4,
 	OPT_LEX_COMPAT,
 	OPT_POSIX_COMPAT,
 	OPT_MAIN,
diff -urN -X ./diff-exclude flex-2.5.31/scan.l flex/scan.l
--- flex-2.5.31/scan.l	2003-04-01 04:51:38.000000000 +0300
+++ flex/scan.l	2004-01-02 12:00:21.000000000 +0200
@@ -88,6 +88,29 @@
 	if ( getenv("POSIXLY_CORRECT") ) \
 		posix_compat = true;
 
+/* Macros need to be clearly separated from surrounding text
+   and this file needs to go through (unpatched) flex untouched. */
+static char *userquote_start = "[" "[]" "]m4_" "userquote_start()";
+static char *userquote_end = "[" "[]" "]m4_" "userquote_end()";
+
+#define QUOTE4_START \
+	do { \
+		if (keep_m4) { \
+			ACTION_ECHO; \
+		} else { \
+			add_action(userquote_start); \
+		} \
+	} while (0)
+
+#define QUOTE4_END \
+	do { \
+		if (keep_m4) { \
+			ACTION_ECHO; \
+		} else { \
+			add_action(userquote_end); \
+		} \
+	} while (0)
+
 %}
 
 %option caseless nodefault stack noyy_top_state
@@ -95,7 +118,7 @@
 
 %x SECT2 SECT2PROLOG SECT3 CODEBLOCK PICKUPDEF SC CARETISBOL NUM QUOTE
 %x FIRSTCCL CCL ACTION RECOVER COMMENT ACTION_STRING PERCENT_BRACE_ACTION
-%x OPTION LINEDIR CODEBLOCK_MATCH_BRACE
+%x OPTION LINEDIR CODEBLOCK_MATCH_BRACE PROLOGLINE
 
 WS		[[:blank:]]+
 OPTWS		[[:blank:]]*
@@ -194,8 +217,11 @@
 <COMMENT>{
 	"*/"		ACTION_ECHO; yy_pop_state();
 	"*"		ACTION_ECHO;
-	[^*\n]+		ACTION_ECHO;
-	[^*\n]*{NL}	++linenum; ACTION_ECHO;
+	[\[\]]		ACTION_ECHO;
+	[^*\[\]\n]+	ACTION_ECHO;
+	[^*\[\]\n]*{NL}	++linenum; ACTION_ECHO;
+	\[\[		QUOTE4_START;
+	\]\]		QUOTE4_END;
 }
 
 <LINEDIR>{
@@ -213,7 +239,11 @@
 <CODEBLOCK>{
 	^"%}".*{NL}	++linenum; BEGIN(INITIAL);
 
-	{NAME}|{NOT_NAME}|.	ACTION_ECHO;
+	\[\[		QUOTE4_START;
+	\]\]		QUOTE4_END;
+
+	[^\n\]\[]+	ACTION_ECHO;
+	[\]\[]		ACTION_ECHO;
 
 	{NL}		{
 			++linenum;
@@ -242,10 +272,25 @@
                 buf_strnappend(&top_buf, yytext, yyleng);
             }
 
-    [^{}\r\n]+  {
+    [^{}\[\]\r\n]+  {
                 buf_strnappend(&top_buf, yytext, yyleng);
                 }
 
+    [\]\[]	buf_strnappend(&top_buf, yytext, yyleng);
+
+    \[\[    {
+            if (keep_m4)
+		buf_strnappend(&top_buf, yytext, yyleng);
+	    else
+		buf_strappend(&top_buf, userquote_start);
+	    }
+    \]\]    {
+            if (keep_m4)
+		buf_strnappend(&top_buf, yytext, yyleng);
+	    else
+		buf_strappend(&top_buf, userquote_end);
+	    }
+
     <<EOF>>     {
                 linenum = brace_start_line;
                 synerr(_("Unmatched '{'"));
@@ -424,33 +469,48 @@
 
 
 <SECT2PROLOG>{
-	^"%{".*	++bracelevel; yyless( 2 );	/* eat only %{ */
-	^"%}".*	--bracelevel; yyless( 2 );	/* eat only %} */
-
-	^{WS}.*	ACTION_ECHO;	/* indented code in prolog */
+	^"%{".*		++bracelevel; yyless( 2 );	/* eat only %{ */
+	^"%}".*		--bracelevel; yyless( 2 );	/* eat only %} */
 
+	^{WS}.*		{	/* indented code in prolog */
+			yyless(0);
+			BEGIN(PROLOGLINE);
+			}
 	^{NOT_WS}.*	{	/* non-indented code */
+			yyless( 0 );	/* put it all back */
 			if ( bracelevel <= 0 )
 				{ /* not in %{ ... %} */
-				yyless( 0 );	/* put it all back */
 				yy_set_bol( 1 );
 				mark_prolog();
 				BEGIN(SECT2);
 				}
 			else
-				ACTION_ECHO;
+				BEGIN(PROLOGLINE);
 			}
 
-	.*		ACTION_ECHO;
-	{NL}	++linenum; ACTION_ECHO;
+	.*		yyless(0); BEGIN(PROLOGLINE);
 
-	<<EOF>>		{
-			mark_prolog();
-			sectnum = 0;
-			yyterminate(); /* to stop the parser */
+	{NL}		++linenum; ACTION_ECHO;
+}
+
+<PROLOGLINE>{
+	[^\]\[\n\r]*	ACTION_ECHO;
+	\[\[		QUOTE4_START;
+	\]\]		QUOTE4_END;
+	[\]\[]		ACTION_ECHO;
+	{NL}		{
+				++linenum;
+				ACTION_ECHO;
+				BEGIN(SECT2PROLOG);
 			}
 }
 
+<PROLOGLINE,SECT2PROLOG><<EOF>>	{
+				mark_prolog();
+				sectnum = 0;
+				yyterminate();
+				}
+
 <SECT2>{
 	^{OPTWS}{NL}	++linenum; /* allow blank lines in section 2 */
 
@@ -768,10 +828,15 @@
 <ACTION>{
 	"{"		ACTION_ECHO; ++bracelevel;
 	"}"		ACTION_ECHO; --bracelevel;
-	[^[:alpha:]_{}"'/\n]+	ACTION_ECHO;
+	[^[:alpha:]_{}\[\]"'/\n]+	ACTION_ECHO;
 	{NAME}		ACTION_ECHO;
 	"'"([^'\\\n]|\\.)*"'"	ACTION_ECHO; /* character constant */
 	\"		ACTION_ECHO; BEGIN(ACTION_STRING);
+	
+	\[\[		QUOTE4_START;
+	\]\]		QUOTE4_END;
+	[\]\[]		ACTION_ECHO;
+	
 	{NL}		{
 			++linenum;
 			ACTION_ECHO;
@@ -788,7 +853,10 @@
 }
 
 <ACTION_STRING>{
-	[^"\\\n]+	ACTION_ECHO;
+	[^"\]\[\\\n]+	ACTION_ECHO;
+	\[\[		QUOTE4_START;
+	\]\]		QUOTE4_END;
+	[\]\[]		ACTION_ECHO;
 	\\.		ACTION_ECHO;
 	{NL}		++linenum; ACTION_ECHO; BEGIN(ACTION);
 	\"		ACTION_ECHO; BEGIN(ACTION);
@@ -812,7 +880,21 @@
 
 
 <SECT3>{
-	.*(\n?)		ECHO;
+	[^\]\[\n\r]*({NL})?	ECHO;
+
+	\[\[		if (keep_m4) {
+				ECHO;
+			} else {
+				fputs(userquote_start, yyout);
+			}
+	\]\]		if (keep_m4) {
+				ECHO;
+			} else {
+				fputs(userquote_end, yyout);
+			}
+
+	[\]\[]		ECHO;
+
 	<<EOF>>		sectnum = 0; yyterminate();
 }
 
diff -urN -X ./diff-exclude flex-2.5.31/tests/Makefile.am flex/tests/Makefile.am
--- flex-2.5.31/tests/Makefile.am	2003-03-27 20:02:59.000000000 +0200
+++ flex/tests/Makefile.am	2004-01-02 11:48:17.000000000 +0200
@@ -40,6 +40,7 @@
 	test-c++-basic \
 	test-posixly-correct \
 	test-posix \
+	test-m4-quotes \
 	test-mem-r \
 	test-mem-nr \
 	test-debug-nr \
@@ -81,6 +82,7 @@
 	test-c++-basic \
 	test-posixly-correct \
 	test-posix \
+	test-m4-quotes \
 	test-mem-r \
 	test-mem-nr \
 	test-debug-nr \
diff -urN -X ./diff-exclude flex-2.5.31/tests/test-m4-quotes/Makefile.am flex/tests/test-m4-quotes/Makefile.am
--- flex-2.5.31/tests/test-m4-quotes/Makefile.am	1970-01-01 03:00:00.000000000 +0300
+++ flex/tests/test-m4-quotes/Makefile.am	2004-01-02 11:49:06.000000000 +0200
@@ -0,0 +1,44 @@
+# This file is part of flex.
+
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+
+# Neither the name of the University nor the names of its contributors
+# may be used to endorse or promote products derived from this software
+# without specific prior written permission.
+
+# THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+# IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+# PURPOSE.
+
+FLEX = $(top_builddir)/flex
+
+builddir = @builddir@
+
+EXTRA_DIST = scanner.l test.input
+CLEANFILES = scanner.c scanner.h TEMPLATE OUTPUT $(OBJS)
+OBJS = scanner.o
+
+AM_CPPFLAGS = -I$(srcdir) -I$(builddir) -I$(top_srcdir) -I$(top_builddir)
+
+testname = TEMPLATE
+
+scanner.c: $(srcdir)/scanner.l
+	$(FLEX) $(LFLAGS) $<
+
+$(testname)$(EXEEXT): $(OBJS)
+	$(CC) -o $@ $(LDFLAGS) $(OBJS) $(LOADLIBES)
+
+test: $(testname)$(EXEEXT)
+	./$(testname)$(EXEEXT) < $(srcdir)/test.input
+
+.c.o:
+	$(CC) -c -o $@ $(AM_CPPFLAGS) $(CPPFLAGS) $(CFLAGS) $<
diff -urN -X ./diff-exclude flex-2.5.31/tests/test-m4-quotes/scanner.l flex/tests/test-m4-quotes/scanner.l
--- flex-2.5.31/tests/test-m4-quotes/scanner.l	1970-01-01 03:00:00.000000000 +0300
+++ flex/tests/test-m4-quotes/scanner.l	2004-01-02 11:49:33.000000000 +0200
@@ -0,0 +1,93 @@
+/*
+ * This file is part of flex.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 
+ * Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE.
+ */
+
+/* [[ grep qtest scanner.c ]] */
+
+%{
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "config.h"
+
+/* qtest: ]] */
+
+static int a[10];
+static int b[10];
+static char *p = "]]"; /* qtest */
+
+#define fx1(x) a[b[0]] /* qtest */
+
+static void xerror(char *msg);
+
+%}
+
+%option 8bit outfile="scanner.c" prefix="test"
+%option nounput nomain noyywrap 
+%option warn
+
+/* qtest: ]] [[ ]] */
+
+%%
+
+%{
+	/* qtest [[ ]] */
+	if (a[a[0]]) ; /* qtest */
+	p = "[["; /* qtest */
+%}
+	if (a[a[0]]) ; /* qtest */
+	p = "[["; /* qtest */
+
+[^a-e]* { }
+a	if (a[a[0]]) ;  /* qtest */
+b	{
+		if (a[a[0]]) ;	/* qtest */
+		p = "[[";	/* qtest */
+	}
+c	/* qtest: ]] [[ ]] */
+	/* qtest: ]] [[ ]] */
+d	if (strlen(p) != 2) xerror("qtest [[ ]]\n");
+e	if (strcmp(p, "[[")) xerror("qtest\n");
+
+
+%%
+
+/* qtest: ]] [[ ]] */
+
+int main(void);
+
+static void xerror(char *msg)
+{
+	fprintf(stderr, "error: %s\n", msg);
+	exit(1);
+}
+
+int
+main ()
+{
+    yyin = stdin;
+    yyout = stdout;
+    yylex();
+    if (a[a[0]]) ;  /* qtest */
+    printf("TEST RETURNING OK.\n");
+    return 0;
+}
diff -urN -X ./diff-exclude flex-2.5.31/tests/test-m4-quotes/test.input flex/tests/test-m4-quotes/test.input
--- flex-2.5.31/tests/test-m4-quotes/test.input	1970-01-01 03:00:00.000000000 +0300
+++ flex/tests/test-m4-quotes/test.input	2004-01-02 11:49:49.000000000 +0200
@@ -0,0 +1,7 @@
+a
+b
+c
+d
+e
+f
+g
diff -urN -X ./diff-exclude flex-2.5.31/tests/test-reject/Makefile.am flex/tests/test-reject/Makefile.am
--- flex-2.5.31/tests/test-reject/Makefile.am	2002-10-11 18:26:43.000000000 +0300
+++ flex/tests/test-reject/Makefile.am	2003-12-28 04:56:02.000000000 +0200
@@ -20,7 +20,7 @@
 # PURPOSE.
 
 
-FLEX = $(top_builddir)/flex
+FLEX = $(top_builddir)/flex -4
 
 EXTRA_DIST = scanner.l test.input
 CLEANFILES = scanner.c test-reject-* OUTPUT $(OBJS)
diff -urN -X ./diff-exclude flex-2.5.31/tests/test-table-opts/Makefile.am flex/tests/test-table-opts/Makefile.am
--- flex-2.5.31/tests/test-table-opts/Makefile.am	2002-10-11 18:26:43.000000000 +0300
+++ flex/tests/test-table-opts/Makefile.am	2003-12-28 04:54:00.000000000 +0200
@@ -29,7 +29,7 @@
 # ------------------------------------------------
 
 
-FLEX = $(top_builddir)/flex
+FLEX = $(top_builddir)/flex -4
 
 testname  := test-table-opts
 allopts   := -Ca -Ce -Cf -CF -Cm -Cem -Cae -Caef -CaeF -Cam -Caem
--- flex-2.5.31/configure.in.orig	2004-07-19 21:19:47.640163000 +0000
+++ flex-2.5.31/configure.in	2004-07-19 21:37:45.584485799 +0000
@@ -101,6 +101,7 @@
 tests/test-include-by-buffer/Makefile
 tests/test-include-by-push/Makefile
 tests/test-include-by-reentrant/Makefile
+tests/test-m4-quotes/Makefile
 tests/test-multiple-scanners-nr/Makefile
 tests/test-multiple-scanners-r/Makefile
 tests/test-noansi-nr/Makefile