https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114730
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> --- I think we need to reject all integral types whose operation range doesn't match the corresponding integer mode range. For enums it depends on the language standard, in general I'd say it's not wanted. Some targets have __int24, we want to reject that as well for example.