http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56158
--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> 2013-02-06 15:59:51 UTC --- [dcl.enum]/7 "For an enumeration whose underlying type is fixed, the values of the enumeration are the values of the underlying type." Because the underlying type in 17.5.2.1.3 is fixed those operations cannot create a value outside the range of the enumeration type. See "The underlying type should be fixed" in http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3110.html
