[Bug libstdc++/80251] Is the is_aggregate meta function missing?

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80251

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
It's only existed for less than a month,. and it requires a new intrinsic from
the compiler which doesn't exist yet.