https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68869
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> --- That's a recent edit to the draft, not yet part of the standard. I don't think it was meant to change any behaviour, so I don't consider this a bug in libstdc++ until I get some clarification whether this change is intended or not.
