1 // PR c++/99650 2 // { dg-do compile { target c++17 } } 3 4 namespace std { 5 template<typename T> struct tuple_size; 6 template<int, typename> struct tuple_element; 7 } 8 9 struct A { 10 int i; getA11 template <int I> void get() { } 12 }; 13 14 template<> struct std::tuple_size<A> { static const int value = 2; }; 15 template<int I> struct std::tuple_element<I,A> { using type = void; }; 16 17 A a = { 42 }; 18 auto [ x, y ] = a; // { dg-error ".std::tuple_element<0, A>::type. is .void." } 19 // { dg-message "in initialization of structured binding variable 'x'" "" { target *-*-* } .-1 } 20