[cfe-dev] error: unknown argument: '-ffoo' => reason ?

[Joerg Sonnenberger]

On Wed, Jan 22, 2014 at 10:45:49AM -0500, Rafael Espíndola wrote:
> >> At least all the ones that just enable or disable a pass. Things like
> >> -malign-double would probably turn a build error into a miscompilation
> >> if ignored, so probably not.
> >
> > I disagree that we should be adding random "disable pass" options. It
> > just doesn't make sense and most of them shouldn't have been applied
> > unconditionally in first place as they are workarounds for optimizer
> > bugs in specific gcc versions. From the list:
> > -  -fexcess-precision must not be dropped silently,
> > -  -fno-check-new / -fcheck-new was discussed before, language lawyers
> >    can comment
> > -  -finput-charset=UTF-8 would be safe to drop as it is the default
> > -  -fsingle-precision-constant potentially changes behavior
> > -  -fno-defer-pop was typically used without good reason, but custom asm
> >    parsers might depend on it, so no.
> > -  -z should likely be fixed to be -Wl,-z
> >
> > I would not change anything except maybe -finput-charset=UTF-8.
> 
> I think we are talking about different things. Yes, at some point it
> would be nice to have a rationale for every option clang supports or
> doesn't.  My point is just that given that it warned on all of those
> (including ABI breaking ones) no long ago, it seems reasonable to
> going back to warning on an explicit list and then work our way over
> that list.

The list is unlikely to get shorter by just waiting. Most of the issues are in
software is between mature and dead. Warning now and error in half a
year only defers the pain.

Joerg