Re: glr-parser: Infinite loop in yymergeOptionSets: yySemanticOption linked list doesn't terminate with NULL

[Paul Hilfinger]

> Hello,
> 
> I am trying to make a glr parser with bison version 2.0
> But the generated code ends up in an infinite loop in the
> yymergeOptionSets function. After looking at that code I see
> that it is iterating over a yysemanticOption linked list that
> ends with a NULL.
> But it never reaches NULL because at some point the
> "current pointer" and "next pointer" are the same so the statement
> yyz = yyz->next continues for ever.

I will try to take a look at this soon.  Yes, it would help quite
a bit if you could send a reproducer as well. There is no particular
need to spend a lot of time cutting it down; the most important thing
is to send enough enough code, data (and instructions) to reproduce
the loop.

> #if (! defined (YYSTACKEXPANDABLE) \
>      && (! defined (__cplusplus) \
>   || (defined (YYLTYPE_IS_TRIVIAL) && YYLTYPE_IS_TRIVIAL \
>       && defined (YYSTYPE_IS_TRIVIAL) && YYSTYPE_IS_TRIVIAL)))
> #define YYSTACKEXPANDABLE 1
> #else
> #define YYSTACKEXPANDABLE 0
> #endif
> 
> Could the semantic differences between C and C++ also be a problem here?

Anything is possible, but probably not in this particular area.  If
the stack can't be expanded, the parser errors out.

Paul Hilfinger