Re: Bison 3.5 - y.tab.c generates compiler warnings

[Paul Eggert]

Thanks for reporting that. As you inferred, the warnings are false 
alarms. I installed the attached patch to prevent the warnings from 
being generated by future Bison versions.
>From 693e6631d5eaee0f82b72468787f65f4b433511e Mon Sep 17 00:00:00 2001
From: Paul Eggert <egg...@cs.ucla.edu>
Date: Wed, 18 Dec 2019 13:34:57 -0800
Subject: [PATCH] =?UTF-8?q?warnings:=20pacify=20=E2=80=98gcc=20-Wchar-subs?=
 =?UTF-8?q?cripts=E2=80=99=20in=20yacc.c?=
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Problem reported by Andy Fiddaman in:
https://lists.gnu.org/r/bug-bison/2019-12/msg00021.html
* data/skeletons/yacc.c (yy_reduce_print, yy_lac, yysyntax_error)
(yyreturn): If I might be a char, write a[+I] instead of a[I],
so that ‘gcc -Wchar-subscripts’ does not complain.
---
 data/skeletons/yacc.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/data/skeletons/yacc.c b/data/skeletons/yacc.c
index 2830c1de..0fb9db0f 100644
--- a/data/skeletons/yacc.c
+++ b/data/skeletons/yacc.c
@@ -755,7 +755,7 @@ do {                                                            \
     {
       YYFPRINTF (stderr, "   $%d = ", yyi + 1);
       yy_symbol_print (stderr,
-                       yystos[yyssp[yyi + 1 - yynrhs]],
+                       yystos[+yyssp[yyi + 1 - yynrhs]],
                        &]b4_rhs_value(yynrhs, yyi + 1)[
                        ]b4_locations_if([, &]b4_rhs_location(yynrhs, yyi + 1))[]dnl
                        b4_user_args[);
@@ -955,12 +955,12 @@ yy_lac (yy_state_t *yyesa, yy_state_t **yyes,
     }
   while (1)
     {
-      int yyrule = yypact[*yyesp];
+      int yyrule = yypact[+*yyesp];
       if (yypact_value_is_default (yyrule)
           || (yyrule += yytoken) < 0 || YYLAST < yyrule
           || yycheck[yyrule] != yytoken)
         {
-          yyrule = yydefact[*yyesp];
+          yyrule = yydefact[+*yyesp];
           if (yyrule == 0)
             {
               YYDPRINTF ((stderr, " Err\n"));
@@ -1184,7 +1184,7 @@ yysyntax_error (YYPTRDIFF_T *yymsg_alloc, char **yymsg,
   */
   if (yytoken != YYEMPTY)
     {
-      int yyn = yypact[*yyssp];
+      int yyn = yypact[+*yyssp];
       YYPTRDIFF_T yysize0 = yytnamerr (YY_NULLPTR, yytname[yytoken]);
       yysize = yysize0;]b4_lac_if([[
       YYDPRINTF ((stderr, "Constructing syntax error message\n"));]])[
@@ -1940,7 +1940,7 @@ yyreturn:
   while (yyssp != yyss)
     {
       yydestruct ("Cleanup: popping",
-                  yystos[*yyssp], yyvsp]b4_locations_if([, yylsp])[]b4_user_args[);
+                  yystos[+*yyssp], yyvsp]b4_locations_if([, yylsp])[]b4_user_args[);
       YYPOPSTACK (1);
     }
 #ifndef yyoverflow
-- 
2.23.0