Re: [RFA] Fix glr.c's YYDEBUG and YY_ERROR_VERBOSE vs. glr.cc

[Paolo Bonzini]

Paolo Bonzini wrote:
> Currently, glr.cc testing is limited in calc.at because of a couple of 
> bugs in glr.cc itself.  These bugs are due to glr.cc's nature of thin 
> wrapper around glr.c.
>
> First, glr.cc sets YY_ERROR_VERBOSE to 0 and glr.c interprets it as a 
> request to *have* verbose errors, thanks to these directives:
>
> #ifdef YYERROR_VERBOSE
> # undef YYERROR_VERBOSE
> # define YYERROR_VERBOSE 1
> #else
> # ...
> #endif
>
> This can be considered a bug in glr.c actually, and the same bug is 
> also there in yacc.c (if you want, the same glr.c hunk applies to 
> yacc.c as well).  This patch fixes it using some preprocessor magic.
>
> Second, yy::parser::set_debug_level is never defined unless %debug is 
> specified.  This because it just sets "::yydebug" to its argument, and 
> the variable is not defined in glr.c unless YYDEBUG is defined.  This 
> patch also fixes it by making the function do nothing unless %debug is 
> specified.
>
> Unluckily, the testsuite changes enabled by this patch are tangled in 
> my %language work, and I'd rather wait for the copyright assignment.  
> In the meanwhile, these are bug fixes that could be applied as 
> uncopyrightable.
>
> Tested with no regressions.
And as usual I forgot the patch.  I must stop writing messages before 
preparing the patch...

Paolo

2006-09-12  Paolo Bonzini  <address@hidden>

        * glr.c (YYERROR_VERBOSE): Do not redefine if defined to 0.
        * glr.cc (debug_stream, set_debug_stream, debug_level, set_debug_level):
        Always provide them.
        (debug_level, set_debug_level) [!YYDEBUG]: Do nothing.

Index: glr.c
===================================================================
RCS file: /sources/bison/bison/data/glr.c,v
retrieving revision 1.188
diff -u -p -r1.188 glr.c
--- glr.c       11 Aug 2006 19:50:14 -0000      1.188
+++ glr.c       12 Sep 2006 09:15:35 -0000
@@ -215,8 +215,12 @@ b4_defines_if([#include @output_header_n
 # define YYDEBUG ]b4_debug_flag[
 #endif
 
-/* Enabling verbose error messages.  */
-#ifdef YYERROR_VERBOSE
+/* Enabling verbose error messages.
+   if YYERROR_VERBOSE is:
+   - 1 -> first succeeds (1 + 0 != 0), second succeeds (1 - 1 + 1 != 0)
+   - 0 -> first fails (0 + 0 == 0), second succeeds (1 - 0 + 1 != 0)
+   - empty -> first fails (+0 == 0), second fails (1 - +1 == 0) */
+#if defined YYERROR_VERBOSE && ((YYERROR_VERBOSE + 0 != 0) == (1 - 
YYERROR_VERBOSE + 1 != 0))
 # undef YYERROR_VERBOSE
 # define YYERROR_VERBOSE 1
 #else
Index: glr.cc
===================================================================
RCS file: /sources/bison/bison/data/glr.cc,v
retrieving revision 1.24
diff -u -p -r1.24 glr.cc
--- glr.cc      9 Jul 2006 20:36:33 -0000       1.24
+++ glr.cc      12 Sep 2006 09:15:35 -0000
@@ -168,6 +168,7 @@ m4_pushdef([b4_parse_param], m4_defn([b4
     yy_symbol_value_print_ (yytype, yyvaluep, yylocationp);
     *yycdebug_ << ')';
   }
+#endif /* ! YYDEBUG */
 
   std::ostream&
   ]b4_parser_class_name[::debug_stream () const
@@ -185,16 +186,19 @@ m4_pushdef([b4_parse_param], m4_defn([b4
   ]b4_parser_class_name[::debug_level_type
   ]b4_parser_class_name[::debug_level () const
   {
+#if YYDEBUG
     return ::yydebug;
+#endif
   }
 
   void
   ]b4_parser_class_name[::set_debug_level (debug_level_type l)
   {
+#if YYDEBUG
     ::yydebug = l;
+#endif
   }
 
-#endif /* ! YYDEBUG */
 ]m4_popdef([b4_parse_param])dnl
 [} // namespace ]b4_namespace[