Re: Bug in Bison-2.1 (and previous)?

[Steve Murphy]

On Fri, 2006-04-14 at 10:02 -0600, Joel E. Denny wrote:

Joel--

Many, many, many thanks. Yes, you are right, the parse-param works, if
I test the same file I process! (blush).

And, moving my decls down below the union got rid of the need for 
the duplicate declarations, and parse-param puts the proper arg in the
calls to yyerror. Miracles happen daily!

Been using this stuff for maybe over 20 years, and I learn something new
even still...!

murf


> On Thu, 13 Apr 2006, Steve Murphy wrote:
> 
> > Trouble is, that I need this to be a pure parser, and I need yyerror to
> > bump a count of the number of syntax errors. So I desparately need that
> > middle argument to pass in a pointer to a struct (or whatever), so I
> > increment the error count. I can't do it as a global!
> 
> Maybe you want:
> 
>   %parse-param { struct YourStruct *struct_ptr_var }
> 
> > So, I tried playing with %parse-param, but it seems to be a boolean; if
> > it's set, I get three args to yyerror; but it doesn't matter what it's
> > set to. If I change it, I get the same results. Its value isn't used.
> 
> It works fine for me in 2.1.
> 
> > In my mind, specifying '%locations' should be sufficient to add the
> > &yylloc arg to the yyerror call (along with whatever else it does), and
> > the %pure-parser should alone add the struct_ptr_var to the call.
> 
> I agree, but backward compatibility is the problem here.  We're discussing 
> ways to clean this up.
> 
> > unless bison is intelligent enough to extract the "my_struct_ptr" from
> > the parse-param value...
> 
> It is, but there's a limitation.  See the documentation.
> 
> > It seems that YYLTYPE and YYSTYPE are not defined at point where the 
> > %{ stuff is included; so I had to insert these definitions myself; Seems
> > to me that if user defined function prototypes are to be declared in
> > these, that the structs & etc that they would naturally use, should be
> > defined before these are possibly used!
> 
> All %{ ... %} before the %union are together called the pre-prologue.  
> All %{ ... %} after the %union are together called the post-prologue. 
> Bison writes the pre-prologue before those definitions, and it writes the 
> post-prologue after them.
> 
> Joel
>