Re: Cannot trace error location when %glr-parser and %pure-parser are used together.

[Akim Demaille]

Hi Slava,

Le 14 déc. 2012 à 18:49, Slava Savitsky <address@hidden> a écrit :

>   Here's a problem: for a grammar with both %glr-parser and %pure-parser
>   declarations a location-aware error reporting function cannot be used.
> 
>   Usually to track the error position one defines "yyerror(msg)" to
>   "print_error(message, &yylval, yychar)", right? In the pure parser
>   "yylval" becomes "yystackp->yylval". The problem is, yyerror(YY_(msg))
>   is called from the "reportAmbiguity" function which does not take the
>   "yystackp" argument.

Do not use the #define yyerror hack, it is brittle.  Just do not
#define it, and let Bison do its job.  The test suite does check
glr + pure + location, so it is expected to work properly.  See
your documentation (you did not specify the version of Bison)
about pure parsers.

> 
>   A possible fix would be:
> 
>   --- /usr/share/bison/glr.cssss 2012-12-14 20:07:40.516065313 +0400
>   +++ /usr/share/bison/glr.csss 2012-12-14 19:49:35.600065872 +0400
>   @@ -1788,8 +1788,7 @@
>   s#endif
>   s
>   s/*ARGSUSED*/ static YYRESULTTAG
>   -yyreportAmbiguity (yyGLRStack* yystackp,
>   -ssssssssssssssssss yySemanticOption* yyx0,
>   +yyreportAmbiguity (yySemanticOption* yyx0,
>   ssss sss ss yySemanticOption* yyx1]b4_pure_formals[)
>   s{
>   ss YYUSE (yyx0);
>   @@ -1900,7 +1899,7 @@
>   ssss sss {
>   ssss sss case 0:
>   ssss sssss yyresolveLocations (yys, 1, yystackp]b4_user_args[);
>   -sss sssss return yyreportAmbiguity (yystackp, yybest,
>   yyp]b4_pure_args[);
>   +sss sssss return yyreportAmbiguity (yybest, yyp]b4_pure_args[);
>   ssss sssss break;
>   ssss sss case 1:
>   ssss sssss yymerge = yytrue;
> 
>   Slava Savitskiy.

FWIW, I don't know what happened here, but the patch was damaged.