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

[jakub at gcc dot gnu.org]

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



--- Comment #11 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-12-06 
18:27:03 UTC ---

In any case, I'd limit the

              /* If there is a mismatch, do warn.  */

              else if (warn_pointer_sign)

                WARN_FOR_ASSIGNMENT (location, OPT_Wpointer_sign,

                                     G_("pointer targets in passing argument "

                                        "%d of %qE differ in signedness"),

                                     G_("pointer targets in assignment "  

                                        "differ in signedness"),

                                     G_("pointer targets in initialization "

                                        "differ in signedness"),

                                     G_("pointer targets in return differ "

                                        "in signedness"));

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.