[Bug c++/88335] Implement P1073R3, C++20 immediate functions (consteval).

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88335

--- Comment #11 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 47042
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=47042&action=edit
gcc10-pr88335.patch

Untested patch.