[Bug libstdc++/91456] std::function and std::is_invocable_r do not understand guaranteed elision

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91456

--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to 康桓瑋 from comment #6)
> Should is_nothrow_invocable_r be fixed too?

Yes, and that's been done at last. Thanks for pointing it out.