[Bug c/39464] [4.6/4.7/4.8 Regression] Attribute may_alias causes invalid warning

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39464

--- Comment #12 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-12-06 19:29:09 UTC ---
(In reply to comment #11)
> warning to actual sign differences only, i.e.
>               else if (warn_pointer_sign
>                        && TYPE_UNSIGNED (mvl) != TYPE_UNSIGNED (mvr))
> If we want to warn about other cases (I think they are generally outside of the
> scope of ISO C anyway), then we should have a differently worded warning after
> this one for the TYPE_UNSIGNED (mvl) == TYPE_UNSIGNED (mvr) case.

The only case which is not outside of the scope of ISO C is "char" vs "signed
char" vs "unsigned char"  They are all three distinct types and we should get a
warning about them.