|
111
|
1 // { dg-do compile { target c++11 } }
|
|
|
2 template<typename _Tp>
|
|
|
3 _Tp&& declval() noexcept;
|
|
|
4
|
|
|
5 template<bool b>
|
|
|
6 struct bt {
|
|
|
7 static constexpr bool value = b;
|
|
|
8 };
|
|
|
9
|
|
|
10 template <typename To_, typename... From_>
|
|
|
11 class my_is_convertible_many {
|
|
|
12 private:
|
|
|
13 template <typename To>
|
|
|
14 struct indirector {
|
|
|
15 indirector(To);
|
|
|
16 };
|
|
|
17
|
|
|
18 template <typename To, typename... From>
|
|
|
19 struct tag {};
|
|
|
20
|
|
|
21 template <typename To, typename... From>
|
|
|
22 static auto test(tag<To, From...>)
|
|
|
23 -> decltype(indirector<To>({declval<From>()...}), bt<true>());
|
|
|
24 static auto test(...)
|
|
|
25 -> bt<false>;
|
|
|
26
|
|
|
27 public:
|
|
|
28 static constexpr bool value = decltype(test(tag<To_, From_...>()))::value;
|
|
|
29 };
|
|
|
30
|
|
|
31 struct A {};
|
|
|
32 struct B {};
|
|
|
33 struct C {};
|
|
|
34
|
|
|
35 struct Test {
|
|
|
36 Test(A, A);
|
|
|
37 //Test(B, B);
|
|
|
38 explicit Test(C, C);
|
|
|
39 };
|
|
|
40
|
|
|
41 int main() {
|
|
|
42 static_assert(my_is_convertible_many<Test, A, A>::value,""); // true, correct
|
|
|
43 static_assert(!my_is_convertible_many<Test, B, B>::value,""); // false, correct
|
|
|
44 static_assert(!my_is_convertible_many<Test, C, C>::value,""); // error
|
|
|
45 return 0;
|
|
|
46 }
|
