1 // { dg-do compile { target c++17 } }
4 template<typename T> struct tuple_size;
5 template<int, typename> struct tuple_element;
8 struct A1 { int i,j; } a1;
9 template<> struct std::tuple_size<A1> { };
10 void f1() { auto [ x ] = a1; } // { dg-error "is not an integral constant expression" }
12 struct A2 { int i,j; } a2;
13 template<> struct std::tuple_size<A2> { enum { value = 5 }; };
14 void f2() { auto [ x ] = a2; } // { dg-error "only 1 name provided" }
15 // { dg-message "decomposes into 5" "" { target *-*-* } .-1 }
17 struct A3 { int i,j; } a3;
18 template<> struct std::tuple_size<A3> { enum { value = 1 }; };
19 void f3() { auto [ x ] = a3; } // { dg-error "get" }
21 struct A3a { int i,j; int get(); } a3a;
22 template<> struct std::tuple_size<A3a> { enum { value = 1 }; };
23 void f3a() { auto [ x ] = a3a; } // { dg-error "get" }
25 struct A3b { int i,j; } a3b;
27 template<> struct std::tuple_size<A3b> { enum { value = 1 }; };
28 void f3b() { auto [ x ] = a3b; } // { dg-error "get<0>" }
32 template <int I> int& get() { return ar[I]; }
34 template<> struct std::tuple_size<A4> { enum { value = 3 }; };
35 void f4() { auto [ x, y, z ] = a4; } // { dg-error "tuple_element" }
38 template <int I> int& get(A5&& a);
39 template<> struct std::tuple_size<A5> { enum { value = 3 }; };
40 void f5() { auto [ x, y, z ] = a5; } // { dg-error "tuple_element" }
43 template <int I> int& get(A6&& a);
44 template<> struct std::tuple_size<A6> { enum { value = 3 }; };
45 template<> struct std::tuple_element<0, A6> { };
46 void f6() { auto [ x, y, z ] = a6; } // { dg-error "no type named .type" }