Re: Problem with Bison 1.35

[Michael J. Saletnik]

Vojtech Toman wrote:

 > parser generated by 1.28 was ok, but parser generated by 1.35
 > crashes with stack overflow

I'm very new to the world of Bison and Flex, but I spent the better
part of today figuring this one out, and just located this mailing
list to share what I found.
:-)

The problem seems to be this code in bison.simple, which was added in
1.34a according to the ChangeLog:

#if (! defined (yyoverflow) \
     && (! defined (__cplusplus) \
         || (YYLTYPE_IS_TRIVIAL && YYSTYPE_IS_TRIVIAL)))

The idea is that if using C++, all the stack-growth code is only valid
if both YYLTYPE and YYSTYPE are trivial types. Makes sense.

However, I don't use the location stack (that the right terminology?),
and so reader_output_yylsp() is never called, code to define
YYLSP_NEEDED and YYLTYPE is not written, and most importantly
YYLTYPE_IS_TRIVIAL is never defined, and my stacks will never grow.

I believe the correct solution is to not require YYLTYPE_IS_TRIVIAL in
this conditional if YYLTYPE (or should it be YYLSP_NEEDED ?) is
undefined.

Thoughts?

-- 
{michael}