1 // { dg-options "-std=c++17 -fconcepts" } 2 3 template<typename T> C()4 concept bool C() { return __is_class(T); } 5 6 template<typename T> 7 struct S1 { S1S18 S1(double) requires C<T>() { } 9 }; 10 11 template<typename T> 12 struct S2 : S1<T> { // { dg-error "matching" } 13 using S1<T>::S1; 14 }; 15 main()16int main() { 17 S2<int> s; // { dg-error "deleted function" } 18 } 19