bison bug
Stefan Vorkoetter
svorkoetter@maplesoft.com
Wed Mar 29 20:21:00 GMT 2006
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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