Re: FYI: fixed yycheck signed/unsigned comparison warnings

[Joel E. Denny]

On Fri, 11 Aug 2006, Paul Eggert wrote:

> "Joel E. Denny" <address@hidden> writes:
> 
> > I configure bison with --enable-gcc-warnings.  I tried adding a new token 
> > to parse-gram.y today, but it failed to compile as gcc complained of 
> > comparisons between signed and unsigned for yycheck.
> 
> In practice that warning causes a lot of makework, and I think it
> harms more than it helps since the extra casts might disguise other
> problems.

It occurs to me now that I really cast the wrong thing.  In 
yycheck[i]==other_value, I shouldn't have cast yycheck[i] to int.  I 
should have cast other_value to unsigned int.  That should be ok since the 
code is obviously assuming other_value is greater than zero, or the 
comparison would be broken anyway.  Would that cast disguise any problems 
that -Wno-sign-compare doesn't also disguise?

> I installed the following patch to disable that warning
> instead of having the casts.

I fear we may lose legitimate warnings.  It seems better to lose this 
warning only for some well examined cases rather than for all future 
cases.

Joel