https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61568
--- Comment #2 from Melissa <myriachan at cox dot net> --- (In reply to Harald van Dijk from comment #1) > The C++ standard requires an unscoped enumeration type with an underlying > type that is not fixed to promote to signed int, if signed int is capable of > representing all the values in the enumeration's range. And the > enumeration's range depends on the values of the enumeration constants, not > on the enumeration's underlying type, so it requires this even if the > underlying type is unsigned int. This may be confusing, but I think that > what GCC implements is exactly what the standard requires, and that there is > no bug in GCC here. I think you're right about this, Harold, particularly because clang exhibits the same behavior. (Visual Studio 2012 and 2013 don't, but they use an underlying type of "signed int"; this makes MSVS equally compliant under this interpretation of the Standard but for a different reason.) But I also think that the Standard is being a little silly here. It seems broken to me that an enum promotes differently than its underlying type does. Maybe that compilers are permitted to do this should be reported as a possible erratum in the Standard.
