https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118765
--- Comment #5 from Joseph S. Myers <jsm28 at gcc dot gnu.org> --- What do you mean by "doesn't work"? Please state both what you expect (based on C23 with bug fixes that postdate the integration of the original proposal) and what you see. As per CD1 comments GB-032 and FR-107 (see N3108 for CD1 ballot resolutions), multiple declarations of a union with members in a different order can't work with initialization, so in final C23 it's not allowed.