https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94645
--- Comment #8 from Rafael Avila de Espindola <rafael at espindo dot la> --- The internal compiler error reduces to struct unordered_map { int cend() const noexcept; }; template <typename a> concept HasMapInterface = requires(a t) { t.cend(); }; template <typename Mapper> requires HasMapInterface<decltype(Mapper::map())> struct l { friend void foo(l opt) { ([]() {})(); } }; struct p { static unordered_map map(); }; void g(l<p> *y) { foo(*y); }