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Date: Wed, 29 Mar 2006 11:35:53 -0500
From: Stefan Vorkoetter <svorkoetter AT maplesoft DOT com>
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Subject: bison bug
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The latest version of bison appears to be broken.

Regardless of the grammar input file, the generated y.tab.c file contains a syntax error in the definition of yyparse when __STDC__ and YYPARSE_PARAM are not defined. Specifically, the generated code looks like:


int
yyparse ()
    ;
{
  int yystate;
  ...


That first ; should not be there.

I'm not a bison internals expert, but I see that it's using m4 to do most of its work. I'm no m4 expert either, so I can't tell if the problem is in the bison input file, or a bug in m4.


~ [518] $ bison --version
bison (GNU Bison) 2.1
Written by Robert Corbett and Richard Stallman.

~ [519] $ m4 --version
GNU M4 1.4.4
Written by Rene' Seindal.


I used the following trivial grammar file, grammar.y, to reproduce the bug:


%{
#define YYMAXDEPTH 1024
%}

%token A B

%%

C: A B { } ;


Then, the command line bison -y -d grammar.y produces a y.tab.c file with the offending error on line 828.

-- 
Stefan Vorkoetter
Maplesoft


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