1 // { dg-do compile { target c++11 } } 2 3 namespace std { template <class T> T&& declval(); } 4 5 template<typename _Tp, typename... _Args> 6 class is_constructible_mini 7 { 8 typedef char __one; 9 typedef struct { char __arr[2]; } __two; 10 11 template<typename _Tp1, typename... _Args1> 12 static decltype(::new _Tp1(std::declval<_Args1>()...), __one()) 13 __test(int); 14 15 template<typename, typename...> 16 static __two __test(...); 17 18 public: 19 static const bool value = sizeof(__test<_Tp, _Args...>(0)) == 1; 20 }; 21 22 /* 23 template<typename _Tp> 24 class is_constructible_mini<_Tp> 25 { 26 typedef char __one; 27 typedef struct { char __arr[2]; } __two; 28 29 template<typename _Tp1> 30 static decltype(::new _Tp1, __one()) __test(int); 31 32 template<typename> 33 static __two __test(...); 34 35 public: 36 static const bool value 37 = sizeof(__test<typename std::remove_cv<_Tp>::type>(0)) == 1; 38 }; 39 */ 40 41 struct A 42 { 43 A(int); 44 }; 45 46 struct B { }; 47 48 static_assert( is_constructible_mini<A, int>::value, ""); 49 static_assert( is_constructible_mini<A, A>::value, ""); 50 static_assert( !is_constructible_mini<A, int, double>::value, ""); 51 52 static_assert( !is_constructible_mini<A>::value, ""); // doesn't compile without the 53 // partial specialization 54 55 static_assert( is_constructible_mini<B>::value, ""); 56 static_assert( is_constructible_mini<const B>::value, ""); 57