+[[input.y:4.4-15: type clash on default action: <bar> != <>
+input.y:5.4-8: type clash on default action: <bar> != <>
+input.y:6.4: empty rule for typed nonterminal, and no action
+]])
+
+AT_CLEANUP
+
+
+
+## ----------------------- ##
+## Torturing the Scanner. ##
+## ----------------------- ##
+
+# Be sure to compile and run, so that the C compiler checks what
+# we do.
+
+AT_SETUP([Torturing the Scanner])
+
+AT_DATA_GRAMMAR([input.y],
+[[%{
+/* This is seen in GCC: a %{ and %} in middle of a comment. */
+const char *foo = "So %{ and %} can be here too.";
+
+#ifdef __STDC__
+/\
+* A comment with backslash-newlines in it. %{ %} *\
+/
+
+char str[] = "\\
+" A string with backslash-newlines in it %{ %} \\
+"";
+
+char apostrophe = '\\
+'\
+';
+#endif
+
+#include <stdio.h>
+%}
+/* %{ and %} can be here too. */
+
+%{
+/* Exercise pre-prologue dependency to %union. */
+typedef int value_t;
+%}
+
+/* Exercise M4 quoting: '@:>@@:>@', 0. */
+
+/* Also exercise %union. */
+%union
+{
+ value_t ival; /* A comment to exercise an old bug. */
+};
+
+
+/* Exercise post-prologue dependency to %union. */
+%{
+static YYSTYPE value_t_as_yystype (value_t val);
+
+/* Exercise quotes in declarations. */
+char quote[] = "@:>@@:>@,";
+%}
+
+%{
+static void yyerror (const char *s);
+static int yylex (void);
+%}
+
+%type <ival> '@<:@'
+
+/* Exercise quotes in strings. */
+%token FAKE "fake @<:@@:>@ \a\b\f\n\r\t\v\"\'\?\\\u005B\U0000005c ??!??'??(??)??-??/??<??=??> \x0\0"
+
+%%
+/* Exercise M4 quoting: '@:>@@:>@', @<:@, 1. */
+exp: '@<:@' '\1' two '$' '@' '{' oline output
+ {
+ /* Exercise quotes in braces. */
+ char tmp[] = "@<:@%c@:>@,\n";
+ printf (tmp, $1);
+ }
+;
+
+two: '\x000000000000000000000000000000000000000000000000000000000000000000002';
+oline: '@' 'o' 'l' 'i' 'n' 'e' '@' '_' '_' 'o' 'l' 'i' 'n' 'e' '_' '_';
+output: '#' 'o' 'u' 't' 'p' 'u' 't' ' ';
+%%
+/* Exercise M4 quoting: '@:>@@:>@', @<:@, 2. */
+
+static YYSTYPE
+value_t_as_yystype (value_t val)
+{
+ YYSTYPE res;
+ res.ival = val;
+ return res;
+}
+
+static int
+yylex (void)
+{
+ static const char *input = "@<:@\1\2$@{@oline@__@&t@oline__\
+#output "; /* "
+ */
+ yylval = value_t_as_yystype (*input);
+ return *input++;
+}
+
+static void
+yyerror (const char *msg)
+{
+ fprintf (stderr, "%s\n", msg);
+}
+]])
+
+# Pacify Emacs'font-lock-mode: "
+
+AT_DATA([main.c],
+[[typedef int value_t;
+#include "input.h"
+
+int yyparse (void);
+
+int
+main (void)
+{
+ return yyparse ();
+}
+]])
+
+AT_CHECK([bison -d -v -o input.c input.y])
+AT_COMPILE([input.o], [-c input.c])
+AT_COMPILE([main.o], [-c main.c])
+AT_COMPILE([input], [input.o main.o])
+AT_PARSER_CHECK([./input], 0,
+[[[@<:@],