[Bug c++/94645] incorrect concept evaluation with decltype, plus internal erropr

[rafael at espindo dot la]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94645

--- Comment #2 from Rafael Avila de Espindola <rafael at espindo dot la> ---
This reduces to just

template <typename a> concept HasMapInterface = requires(a t) { t.cend; };
template <typename Mapper>
requires HasMapInterface<decltype(Mapper::map())> struct l {};
struct mymap {
  int cend();
};
struct p {
  static mymap map();
};
l<p> q;