https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97778
Jonathan Wakely <redi at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Resolution|--- |DUPLICATE Status|UNCONFIRMED |RESOLVED --- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> --- Reduced: template <typename T> struct hash { auto operator()(T) const noexcept { return 0; } }; template <typename ...T> auto hash_combine(T&& ...) noexcept { return 0; } template<typename... T> struct tuple { }; template<typename F, typename... T> auto apply(F, tuple<T...>) { } template <typename ...T> struct hash<tuple<T...>> { auto operator()(tuple<T...> t) const { return apply(hash_combine<T...>, t); } }; int main() { using T = tuple<int>; hash<T> h; T t; h(t); } Confirmed as fixed by r11-2420 which fixed PR c++/64194 *** This bug has been marked as a duplicate of bug 64194 ***