Xref:	news2.mv.net comp.os.msdos.djgpp:3723
From:	John Bodfish <johnb AT als DOT ameritech DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Problems with BISON
Date:	Thu, 09 May 96 18:09:07 PDT
Organization:	Northwestern University, Evanston, IL, US
Lines:	52
Message-ID:	<NEWTNews.831691900.32553.johnb@johnb.als.ameritech.com>
References:	<4mt50i$jba AT newsbf02 DOT news DOT aol DOT com>
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To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

In article <4mt50i$jba AT newsbf02 DOT news DOT aol DOT com>, <hlgpeter AT aol DOT com> writes:

> I wrote a small parser and wanted BISON to work in debug mode.
> I therefore defined the following:
> 
> %{
> 
> .....
> #define YYDEBUG 1
> 
> %} 
> 
> Bison was also invoked with option -t.
> 
> The problem is that I do not see any debug information. I do not see
> any states at all.
> 
The info for bison says:

   "Once you have compiled the program with trace facilities, the way to
request a trace is to store a nonzero value in the variable `yydebug'.
You can do this by making the C code do it (in `main', perhaps), or you
can alter the value with a C debugger."

I have the following in my *.y file, in place of your #define:

	#ifdef DEBUG
	#define YYERROR_VERBOSE
	#endif

and in main():

	#ifdef DEBUG
	  yydebug = 1;
	#endif

Finally I use the --debug option (and the -v option is helpful;
again, consult the info file) on the bison command line (which
causes bison to emit a definition for YYDEBUG) and I define DEBUG
on the compiler command line with "-DDEBUG". This seems to work
fine; here's the kind of trace info I get:

Starting parse
Entering state 0
Reading a token: --(end of buffer or a NUL)
--accepting rule at line 255 ("; This is file DOUTILS.ASM
")
Next token is 264 (COMMENT)

John

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