[Bug c/115516] constexpr use before C23 could give a better error message

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115516

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Sorry, this was about C, not C++.  And apparently C++ manages to warn about
that in
cp_parser_diagnose_invalid_type_name through
if (cxx_dialect < cxx11 && id == ridpointers[(int)RID_CONSTEXPR])
check.