Re: [PATCH] -Werror: fix for rules useless in parser after conflicts.

[Joel E. Denny]

On Sun, 1 Aug 2010, Joel E. Denny wrote:

> I am thinking of including this patch in bison 2.4.3.  I wrote it while 
> considering a complaint on comp.compilers saying that -Werror doesn't 
> work:
> 
>   http://compilers.iecc.com/comparch/article/10-07-039
> 
> As far as I can tell, the only warning on which -Werror has no effect is 
> the warning that a rule is useless in the parser due to conflicts.  
> Because bison explicitly labels these messages as warnings, I see this 
> behavior as a bug, and this patch fixes it.  But is there any backward 
> compatibility problem to consider here?

Given the discussion I recently posted about proper usage of -Werror (that 
is, a formal release of a project should not pass -Werror to bison), and 
given that useless grammar rules are a rather severe grammar problem, I'm 
feeling pretty confident about letting -Werror turn useless grammars rules 
into errors in 2.4.3.  So...

> >From 954474bfa1a875eeefe9aa1989d9c7be6f64726b Mon Sep 17 00:00:00 2001
> From: Joel E. Denny <address@hidden>
> Date: Sun, 1 Aug 2010 18:51:46 -0400
> Subject: [PATCH] -Werror: fix for rules useless in parser after conflicts.

I pushed this to branch-2.4.3, branch-2.5, and master.