Re: GCC-3.2.2 bootstrap FAILURE: 1 reduce/reduce conflict inobjc-parse.y

["Joseph S. Myers" <jsm28 at cam dot ac dot uk>]

On Wed, 29 Jan 2003, Ziemowit Laski wrote:

> What does "Neil's parser" refer to, exactly?  I apologize for being
> out of the loop on this...

The recursive descent C parser Neil Booth is writing.

> As far as ObjC conflicts breaking the C grammar, this is possible iff 
> the
> ObjC-conflict-prone state can be reached from "pure C" states.
> This probably holds true for some of the shift/reduce conflicts,
> but these can be analyzed one-by-one and resolved via appropriate %prec
> annotations.

I'll expect such an analysis (with the conflicts being resolved explicitly
where possible) for any merger of the existing parsers into one parser
that decides at runtime.  (I don't care about conflicts only involved in
error recovery.)  C at present has just one conflict not involving error
recovery.

There used to be a comment at the top of c-parse.in listing the conflicts
- which was removed as very out of date and not maintained.  If the
conflicts get genuinely minimised then writing a new such comment would be
worthwhile.

The reduce/reduce conflict meaning being unable to use %expect leads to an
increased risk that it won't be noticed (in the absence of %expect) that
parser changes add conflicts they shouldn't.  This is maintenance risk for
C in the presence of a single parser with such a conflict.

-- 
Joseph S. Myers
jsm28@cam.ac.uk