[Bug libstdc++/107761] Implement C++23

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107761

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
OK that's great, thanks for clarifying. (I haven't looked at the impl on
godbolt yet, sorry)