[Bug c/66773] sign-compare warning for == and != are pretty useless

["egallager at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66773

Eric Gallager <egallager at gcc dot gnu.org> changed:

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                 CC|                            |egallager at gcc dot gnu.org

--- Comment #25 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Segher Boessenkool from comment #16)
> (In reply to Eric Gallager from comment #13)
> > > Yes.  You should not use casts, except in some very specific cases, and
> > > most of the uses you see "in the wild" are a bad idea.  Sometimes I
> > > wonder if we should have a -Wcast ("Warn for any cast.").
> > 
> > I get the feeling that such a warning would be extremely noisy and that
> > no one would use it.
> 
> It was not meant as a serious suggestion of course, or I would have done
> this many many years ago.

OK, but I still think some of the ideas I came up with in response to it are
good ideas, though; I'd like to amend this comment #13 in response:

> It would probably be better to go about improving existing cast-related
> warnings, or adding new ones for specific cases, rather than breaking out
> such a broad hammer. For example, the fixits that David Malcolm added for
> -Wold-style-cast are very nice; extending those to apply to more
> cast-related warnings would be a good improvement (I've been meaning to
> open a separate bug about this). These would all be better, more-specific
> warnings to add:
> * -Wcast-to-the-same-type (bug 85043)
> * -Wcast-variadic-function-type (bug 87379)
> * -Wfunctional-cast (bug 69818)
> * -Wcast-enum (bug 30357)
> * -Wold-style-cast-qual (fixit would suggest using const_cast instead)
> * -Wold-style-useless-cast
> * Any of clang's cast-related warnings that we currently don't have yet;
> grep https://clang.llvm.org/docs/DiagnosticsReference.html for the word
> "cast" to find some

To this list, I'd like to add:
* -Wold-style-cast-align (similar to -Wold-style-cast-qual)
* -Wuseless-old-style-cast (as an alternate spelling of
-Wold-style-useless-cast)