"Use" parse parameters.

* data/c.m4 (b4_parse_param_for, b4_parse_param_use): New.
* data/glr.c, data/glr.cc: Use them.
* data/glr.c (YYUSE): Have a C++ definition that supports
non-pointer types.

data/c.m4

@@ -95,6 +95,27 @@ m4_define_default([b4_parse_param])
 m4_define([b4_parse_param],
 b4_parse_param))
 
+# b4_parse_param_for(DECL, FORMAL, BODY)
+# ---------------------------------------
+# Iterate over the user parameters, binding the declaration to DECL,
+# the formal name to FORMAL, and evaluating the BODY.
+m4_define([b4_parse_param_for],
+[m4_foreach([$1_$2], m4_defn([b4_parse_param]),
+[m4_pushdef([$1], m4_fst($1_$2))dnl
+m4_pushdef([$2], m4_shift($1_$2))dnl
+$3[]dnl
+m4_popdef([$2])dnl
+m4_popdef([$1])dnl
+])])
+
+# b4_parse_param_use
+# ------------------
+# `YYUSE' all the parse-params.
+# WARNING: Ends with a dnl, there must be nothing behind it.
+m4_define([b4_parse_param_use],
+[b4_parse_param_for([Decl], [Formal], [  YYUSE (Formal);
+])dnl
+])
 
 ## ------------ ##
 ## Data Types.  ##
@@ -348,6 +369,11 @@ m4_define([b4_syncline],
        [[#]line $1 $2])])
 
 
+
+## -------------- ##
+## User actions.  ##
+## -------------- ##
+
 # b4_symbol_actions(FILENAME, LINENO,
 #                   SYMBOL-TAG, SYMBOL-NUM,
 #                   SYMBOL-ACTION, SYMBOL-TYPENAME)
@@ -386,7 +412,9 @@ m4_ifset([b4_parse_param], [, b4_parse_param]))[
 {
   YYUSE (yyvaluep);
 ]b4_location_if([  YYUSE (yylocationp);
-])[
+])dnl
+b4_parse_param_use[]dnl
+[
   if (!yymsg)
     yymsg = "Deleting";
   YY_SYMBOL_PRINT (yymsg, yytype, yyvaluep, yylocationp);
@@ -422,8 +450,8 @@ m4_ifset([b4_parse_param], [, b4_parse_param]))[
   YYUSE (yyvaluep);
 ]b4_location_if([  YYUSE (yylocationp);
 ])dnl
-[
-  if (yytype < YYNTOKENS)
+b4_parse_param_use[]dnl
+[  if (yytype < YYNTOKENS)
     YYFPRINTF (yyoutput, "token %s (", yytname[yytype]);
   else
     YYFPRINTF (yyoutput, "nterm %s (", yytname[yytype]);

data/glr.c

@@ -257,7 +257,11 @@ b4_syncline([@oline@], [@ofile@])
 #endif
 
 /* Suppress unused-variable warnings by "using" E.  */
-#define YYUSE(e) do {;} while (/*CONSTCOND*/ yyfalse && (e))
+#if __cplusplus
+# define YYUSE(e) (void) (e)
+#else
+# define YYUSE(e) do {;} while (/*CONSTCOND*/ yyfalse && (e))
+#endif
 
 #ifndef YYFREE
 # define YYFREE free
@@ -868,8 +872,8 @@ yyuserAction (yyRuleNum yyn, int yyrhslen, yyGLRStackItem* yyvsp,
   yybool yynormal __attribute__ ((__unused__)) =
     (yystack->yysplitPoint == NULL);
   int yylow;
-
-# undef yyerrok
+]b4_parse_param_use[]dnl
+[# undef yyerrok
 # define yyerrok (yystack->yyerrState = 0)
 # undef YYACCEPT
 # define YYACCEPT return yyaccept
@@ -1372,7 +1376,10 @@ yy_reduce_print (yyGLRStack* yystack, size_t yyk, yyRuleNum yyrule,
   yyGLRStackItem* yyvsp = (yyGLRStackItem*) yystack->yytops.yystates[yyk];
   int yylow = 1;
   int yyi;
-  YYFPRINTF (stderr, "Reducing stack %lu by rule %d (line %lu):\n",
+  YYUSE (yyvalp);
+  YYUSE (yylocp);
+]b4_parse_param_use[]dnl
+[  YYFPRINTF (stderr, "Reducing stack %lu by rule %d (line %lu):\n",
 	     (unsigned long int) yyk, yyrule - 1,
 	     (unsigned long int) yyrline[yyrule]);
   /* Print the symbols being reduced, and their result.  */

data/glr.cc

@@ -53,7 +53,9 @@ b4_location_if([,
                              [yylocationp]]])[]dnl
 m4_ifset([b4_parse_param], [, b4_parse_param]))[
 {
-  (void) yyoutput;
+  YYUSE (yyoutput);
+]b4_parse_param_use[]dnl
+[
   yyparser.yysymprint_ (yytype, yyvaluep]b4_location_if([, yylocationp])[);
 }
 ]])
@@ -70,6 +72,8 @@ m4_prepend([b4_epilogue],
     b4_parse_param,
     [[const char* msg], [msg]])[
 {
+]b4_parse_param_use[]dnl
+[
   yyparser.error (*yylocationp, msg);
 }
 
@@ -106,11 +110,11 @@ m4_popdef([b4_parse_param])dnl
                            const semantic_type* yyvaluep, const location_type* yylocationp)
   {
     /* Pacify ``unused variable'' warnings.  */
-    (void) yyvaluep;
-    (void) yylocationp;
+    YYUSE (yyvaluep);
+    YYUSE (yylocationp);
     /* Backward compatibility, but should be removed eventually. */
     std::ostream& cdebug_ = *yycdebug_;
-    (void) cdebug_;
+    YYUSE (cdebug_);
 
     *yycdebug_ << (yytype < YYNTOKENS ? "token" : "nterm")
   	       << ' ' << yytname[yytype] << " ("