[Bug c++/80294] [C++1z] ICE with constexpr and inheritance

[trippels at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80294

--- Comment #4 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
Created attachment 41113
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41113&action=edit
Somewhat reduced testcase