[Bug c++/119497] Improve diagnostic for failed assert(expr) in constexpr context

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119497

--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
There's no reason to have any special case for scenario 1. It should give the
same diagnostic as any other invalid use of a non-constant in constexpr
contexts.