|
152
|
1 // PR c++/95143
|
|
|
2 // { dg-do compile { target c++11 } }
|
|
|
3
|
|
|
4 struct false_type {
|
|
|
5 static constexpr bool value = false;
|
|
|
6 };
|
|
|
7
|
|
|
8 struct true_type{
|
|
|
9 static constexpr bool value = true;
|
|
|
10 };
|
|
|
11
|
|
|
12 template<class T>
|
|
|
13 T&& declval() noexcept;
|
|
|
14
|
|
|
15 template<typename T, typename U, typename = U>
|
|
|
16 struct is_static_castable : false_type
|
|
|
17 {};
|
|
|
18 template<typename T, typename U>
|
|
|
19 struct is_static_castable<T, U, decltype(static_cast<U>(declval<T>()))> : true_type
|
|
|
20 {};
|
|
|
21
|
|
|
22 class Base { };
|
|
|
23 struct A { };
|
|
|
24 class B: public Base { };
|
|
|
25
|
|
|
26 int main()
|
|
|
27 {
|
|
|
28 constexpr auto canCast = is_static_castable<A, B>::value;
|
|
|
29 static_assert(!canCast, "");
|
|
|
30 constexpr auto canCast2 = is_static_castable<A, A>::value;
|
|
|
31 static_assert(canCast2, "");
|
|
|
32 }
|
