Re: bison parse-gram.y glr yacc

[Paul Eggert]

twlevo <address@hidden> writes:

> multiple yacc glr statements
> parse-gram.y line 216
>
> %yacc
> %glr-parser
> %yacc
>
> %%
>
> start:
>  ;
>
> %%
>
> this generates a yacc parser, no messages
> on the multiple yacc/glr parser statements.

2006-01-03  Paul Eggert  <address@hidden>

        * doc/bison.texinfo (Bison Options): Say more accurately what
        --yacc does.
        * src/parse-gram.y (rules_or_grammar_declaration): Don't complain
        about declarations in the grammar when in Yacc mode, as POSIX does
        not require a diagnostic when the grammar uses extensions.

Thanks.  I think %yacc isn't supposed to mean "generate a yacc-style
parser", it's supposed to mean "behave more like yacc, if the input is
suitable for yacc".  I installed this patch to clarify things:

Index: doc/bison.texinfo
===================================================================
RCS file: /cvsroot/bison/bison/doc/bison.texinfo,v
retrieving revision 1.170
diff -p -u -r1.170 bison.texinfo
--- doc/bison.texinfo   27 Dec 2005 15:42:44 -0000      1.170
+++ doc/bison.texinfo   3 Jan 2006 22:33:53 -0000
@@ -6677,13 +6677,14 @@ Print the version number of Bison and ex
 @item --print-localedir
 Print the name of the directory containing locale-dependent data.
 
address@hidden 1750
 @item -y
 @itemx --yacc
-Equivalent to @samp{-o y.tab.c}; the parser output file is called
+Act more like the traditional Yacc command.  This can cause
+different diagnostics to be generated, and may change behavior in
+other minor ways.  Most importantly, imitate Yacc's output
+file name conventions, so that the parser output file is called
 @file{y.tab.c}, and the other outputs are called @file{y.output} and
address@hidden  The purpose of this option is to imitate Yacc's output
-file name conventions.  Thus, the following shell script can substitute
address@hidden  Thus, the following shell script can substitute
 for Yacc, and the Bison distribution contains such a script for
 compatibility with @acronym{POSIX}:
 
@@ -6691,6 +6692,12 @@ compatibility with @acronym{POSIX}:
 #! /bin/sh
 bison -y "$@@"
 @end example
+
+The @option{-y}/@option{--yacc} option is intended for use with
+traditional Yacc grammars.  If your grammar uses a Bison extension
+like @samp{%glr-parser}, Bison might not be Yacc-compatible even if
+this option is specified.
+
 @end table
 
 @noindent
Index: src/parse-gram.y
===================================================================
RCS file: /cvsroot/bison/bison/src/parse-gram.y,v
retrieving revision 1.67
diff -p -u -r1.67 parse-gram.y
--- src/parse-gram.y    3 Jan 2006 21:31:57 -0000       1.67
+++ src/parse-gram.y    3 Jan 2006 22:33:53 -0000
@@ -391,10 +391,6 @@ grammar:
 rules_or_grammar_declaration:
   rules
 | grammar_declaration ";"
-    {
-      if (yacc_flag)
-       complain_at (@$, _("POSIX forbids declarations in the grammar"));
-    }
 | error ";"
     {
       yyerrok;