https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99968
Patrick Palka <ppalka at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |ppalka at gcc dot gnu.org --- Comment #6 from Patrick Palka <ppalka at gcc dot gnu.org> --- Reduced: template<typename T> using remove_const_t = T; template<typename T> struct is_scoped_enum { using type = remove_const_t<T>; static constexpr bool value = false; }; enum E { e0 = __is_enum(E), e1 = is_scoped_enum<E>::value }; 99968.C:10:51: required from here 99968.C:4:8: error: enum value type is not ‘INTEGER_TYPE’ nor convertible to the enum 4 | struct is_scoped_enum | ^~~~~~~~~~~~~~ This one seems to have started with r6-598, the same commit that introduced the sanity check.