bjy at mogua.org
Fri Jun 22 23:59:05 CDT 2001
On Fri, Jun 15, 2001 at 08:09:54AM -0700, Francois Gouget wrote:
> I wanted a preprocessed version of the user32.rc file. But Bang
> Jun-Young sent me the files generated by flex/bison which allowed me to
> reproduce the problem. I have not yet found a fix but the problem is in
> the y.tab.c file.
> Bang Jun-Young is using byacc while I'm using bison so the files are
> quite different and about impossible to compare. When I compile
> parser.y I get:
> bison -y -d -t ./parser.y
> conflicts: 2 shift/reduce
I get the same warning with byacc.
> Maybe that's the source of the problem: byacc resolves the conflicts
> differently from bison which causes tehe parse to fail.
Now I think I have found the reason. It was due to a bug in
byacc. From parser.y of revision 1.25:
| tNL /*
* This newline rule will never get reduced because we never
* get the tNL token, unless we explicitely set the 'want_nl'
* flag, which we don't.
* The *ONLY* reason for this to be here is because Berkeley
* yacc (byacc), at least version 1.9, has a bug.
* (identified in the generated parser on the second
* line with:
* static char yysccsid = "@(#)yaccpar 1.9 (Berkeley) 02/21/93";
* This extra rule fixes it.
* The problem is that the expression handling rule "expr: xpr"
* is not reduced on non-terminal tokens, defined above in the
* %token declarations. Token tNL is the only non-terminal that
* can occur. The error becomes visible in the language parsing
* rule below, which looks at the look-ahead token and tests it
* for tNL. However, byacc already generates an error upon reading
* the token instead of keeping it as a lookahead. The reason
* lies in the lack of a $default transition in the "expr : xpr . "
* state (currently state 25). It is probably ommitted because tNL
* is a non-terminal and the state contains 2 s/r conflicts. The
* state enumerates all possible transitions instead of using a
* $default transition.
* All in all, it is a bug in byacc. (period)
I added a line to parser.y (r1.26) as follows:
--- parser.y 2001/06/06 21:04:08 1.26
+++ parser.y 2001/06/23 04:28:52
@@ -423,6 +423,7 @@
want_id = 1;
dont_want_id = 0;
+ | resources tNL
After doing that, I could build Wine successfully again. I'll
send a complete patch including above comment to wine-patches
Bang Jun-Young <bjy at mogua.org>
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