[Bug libstdc++/101263] non-propagating-cache::emplace-deref missing constexpr

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101263

--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Fixed on trunk. It can't be backported without also backporting r12-1068 to fix
PR100368.