https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97661
Marek Polacek <mpolacek at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |mpolacek at gcc dot gnu.org Status|UNCONFIRMED |NEW Last reconfirmed| |2020-11-03 Ever confirmed|0 |1 --- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> --- template <typename...> struct A {}; struct B : A<> {}; template <typename...> struct C { A<> *a; using V = A<>; }; C(A<> *)->C<>; template<typename T> auto declval() -> decltype(T()); template<typename T, typename = typename decltype(C{declval<T *>()})::V> struct D; template<typename> struct J { }; template<typename T> using U = J<D<T>>; void fn () { U<B> u; }