Request: suppress specific warnings at specific places

[Mike Gunter]

If the switches take affect at the line granularity there would seem
to be a straightforward implementation that's orthogonal to most
everything else: store the excluded regions in separate data structure
and check that data structure before printing a message.

        mike


> > GHC's excellent warnings are very helpful.  They would be somewhat
> > more so if it were possible to suppress a warning about a specific bit
> > of code.  One possible syntax (to which I gave no commitment) would be
> > 
> >   {-# WOFF "non-exhaustive pattern matches" #-}
> >   <offending code>
> >   {-# WON "non-exhaustive pattern matches" #-}
> > 
> > .  Another would be
> > 
> >   {-# WOFF 523 #-}
> >   <offending code>
> >   {-# WON 523 #-}
> > 
> > where 523 is a warning number emitted with the warning message.
> > 
> > This would be particularly useful with the recently granted wish for
> > -Werror.
> 
> This would be nice, but it would be tricky to implement: declarations
> have to be tagged with a list of "exceptions" to the prevailing warning
> settings.  I doubt we'll do this any time soon, but patches are welcome
> as usual...
> 
> (of course, the workaround is to put the offending code into a module of
> its own, and use OPTIONS to turn off the appropriate warnings).
> 
> Cheers,
> 	SImon