Check for unrecognized %define variables similar to checking for

unrecognized %code qualifiers.  Check for redefined %define variables.
* data/bison.m4 (b4_check_for_unrecognized_names): New macro that
generalizes...
(b4_check_percent_code_qualifiers): ... this, which now wraps it.
(b4_check_percent_define_variables): New, also wraps it.
* data/glr.c: Unless glr.cc is wrapping glr.c, declare no valid %define
variables using b4_check_percent_define_variables.
* data/glr.cc, data/lalr1.cc: Declare the valid %define variables as
all those exercised in the test suite and all those listed in the
`Default values' section of c++.m4.  Are there others?
* data/push.c, data/yacc.c: Declare no valid %define variables.
* src/muscle_tab.c, src/muscle_tab.h (muscle_find_const): New function,
similar to muscle_find, but it works even when the muscle stores a
const value.
(muscle_grow_used_name_list): New function for constructing the used
name list muscles that b4_check_for_unrecognized_names requires.
* src/parse-gram.y (prologue_declaration): Warn if a variable is
%define'd more than once.  Define the b4_used_percent_define_variables
muscle with muscle_grow_used_name_list.
(grammar_declaration): Abbreviate %code code with
muscle_grow_used_name_list.
* tests/input.at (%define errors): New.

src/muscle_tab.c

@@ -209,6 +209,26 @@ void muscle_pair_list_grow (const char *muscle,
   obstack_free (&muscle_obstack, pair);
 }
 
+
+/*----------------------------------------------------------------------------.
+| Find the value of muscle KEY.  Unlike MUSCLE_FIND, this is always reliable  |
+| to determine whether KEY has a value.                                       |
+`----------------------------------------------------------------------------*/
+
+char const *
+muscle_find_const (char const *key)
+{
+  muscle_entry probe;
+  muscle_entry *result = NULL;
+
+  probe.key = key;
+  result = hash_lookup (muscle_table, &probe);
+  if (result)
+    return result->value;
+  return NULL;
+}
+
+
 /*----------------------------------------------------------------------------.
 | Find the value of muscle KEY.  Abort if muscle_insert was invoked more      |
 | recently than muscle_grow for KEY since muscle_find can't return a          |
@@ -216,7 +236,7 @@ void muscle_pair_list_grow (const char *muscle,
 `----------------------------------------------------------------------------*/
 
 char *
-muscle_find (const char *key)
+muscle_find (char const *key)
 {
   muscle_entry probe;
   muscle_entry *result = NULL;
@@ -276,3 +296,16 @@ muscle_boundary_grow (char const *key, boundary bound)
   muscle_grow (key, extension, "");
   obstack_free (&muscle_obstack, extension);
 }
+
+void
+muscle_grow_used_name_list (char const *key, char const *used_name,
+                            location loc)
+{
+  muscle_grow (key, "[[[[", ",");
+  muscle_grow (key, used_name, "");
+  muscle_grow (key, "]], [[", "");
+  muscle_boundary_grow (key, loc.start);
+  muscle_grow (key, "]], [[", "");
+  muscle_boundary_grow (key, loc.end);
+  muscle_grow (key, "]]]]", "");
+}

src/muscle_tab.h

@@ -26,6 +26,7 @@
 void muscle_init (void);
 void muscle_insert (char const *key, char const *value);
 char *muscle_find (char const *key);
+char const *muscle_find_const (char const *key);
 void muscle_free (void);
 
 
@@ -116,4 +117,12 @@ void muscles_m4_output (FILE *out);
    for special characters in the file name.  */
 void muscle_boundary_grow (char const *key, boundary bound);
 
+/* Grow KEY for the occurrence of the name USED_NAME at LOC appropriately for
+   use with b4_check_for_unrecognized_names in ../data/bison.m4.  USED_NAME
+   is not escaped with digraphs, so it must not contain `[' or `]'.  As a
+   precondition on b4_check_for_unrecognized_names, it can't contain `,'
+   either.  */
+void muscle_grow_used_name_list (char const *key, char const *used_name,
+                                 location loc);
+
 #endif /* not MUSCLE_TAB_H_ */

src/parse-gram.h

@@ -165,8 +165,8 @@
 #if ! defined YYSTYPE && ! defined YYSTYPE_IS_DECLARED
 typedef union YYSTYPE
 {
-/* Line 1546 of yacc.c  */
-#line 98 "parse-gram.y"
+/* Line 1551 of yacc.c  */
+#line 97 "parse-gram.y"
 
   symbol *symbol;
   symbol_list *list;
@@ -178,7 +178,7 @@ typedef union YYSTYPE
   unsigned char character;
 }
 
-/* Line 1546 of yacc.c  */
+/* Line 1551 of yacc.c  */
 #line 183 "parse-gram.h"
 	YYSTYPE;
 # define YYSTYPE_IS_TRIVIAL 1

src/parse-gram.y

@@ -82,7 +82,6 @@ static int current_prec = 0;
 %locations
 %pure-parser
 %error-verbose
-%defines
 %name-prefix="gram_"
 %expect 0
 
@@ -233,7 +232,15 @@ prologue_declaration:
       code_scanner_last_string_free ();
     }
 | "%debug"                         { debug_flag = true; }
-| "%define" STRING content.opt     { muscle_insert ($2, $3); }
+| "%define" STRING content.opt
+    {
+      /* FIXME: Special characters in $2 may break %define.
+         For example: `['.  */
+      if (muscle_find_const ($2))
+        warn_at (@2, _("%s: `%s' redefined"), "%define", $2);
+      muscle_insert ($2, $3);
+      muscle_grow_used_name_list ("used_percent_define_variables", $2, @2);
+    }
 | "%defines"                       { defines_flag = true; }
 | "%defines" STRING
     {
@@ -316,6 +323,8 @@ grammar_declaration:
     }
 | "%code" STRING braceless
     {
+      /* FIXME: Special characters in $2 may break %code.
+         For example: `['.  */
       char const name_prefix[] = "percent_code_";
       char *name = xmalloc (sizeof name_prefix + strlen ($2));
       strcpy (name, name_prefix);
@@ -323,13 +332,7 @@ grammar_declaration:
       muscle_code_grow (uniqstr_new (name), $3, @3);
       free (name);
       code_scanner_last_string_free ();
-      muscle_grow ("used_percent_code_qualifiers", "[[[[", ",");
-      muscle_grow ("used_percent_code_qualifiers", $2, "");
-      muscle_grow ("used_percent_code_qualifiers", "]], [[", "");
-      muscle_boundary_grow ("used_percent_code_qualifiers", @2.start);
-      muscle_grow ("used_percent_code_qualifiers", "]], [[", "");
-      muscle_boundary_grow ("used_percent_code_qualifiers", @2.end);
-      muscle_grow ("used_percent_code_qualifiers", "]]]]", "");
+      muscle_grow_used_name_list ("used_percent_code_qualifiers", $2, @2);
     }
 ;