http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59980
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> --- (In reply to Jason from comment #3) > C-style enums decay to the underlying integer representation, this > particular behaviour helps complicate considering how any modification to > the diagnostic might be implemented. I don't see how the decay is relevant, if the template parameter is of type E then the compiler's IR stores a value with that type, not an integer, so there's no decaying. For the purposes of this diagnostic I don't see any difference between scoped and unscoped enums.