[Bug libstdc++/93795] Out-of-line definition of class member template with 'requires std::invocable' constraint fails to compile

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93795

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Seems unlikely to be a problem with the libstdc++ definition of std::invocable
rather than a compiler bug.