https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117085
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> --- (In reply to Jonathan Wakely from comment #1) > const _CharT* __rep = __formats[__mod]; Oops, we don't need two __rep variables! I suppose this is a bit neater anyway: + if (*__formats[__mod]) [[likely]] + { + __fmt = _GLIBCXX_WIDEN("{:L}"); + __fmt.insert(3u, __formats[__mod]);