2 // { dg-options "-std=c++17 -fconcepts" }
5 constexpr typename T::type::value_type _v = T::type::value;
7 template <class T> concept bool IsTrue_() { return _v<T>; }
9 template <class T> concept bool Unpossible() {
10 return IsTrue_<T &&>();
13 template <class> constexpr bool unpossible() { return false; }
15 constexpr bool unpossible() { return true; }
17 static_assert((!unpossible<void>()), "");