1 //===----------------------------------------------------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 // <functional>
11 //
12 // template <class T>
13 // struct unwrap_reference;
14 //
15 // template <class T>
16 // using unwrap_reference_t = typename unwrap_reference<T>::type;
17
18 // UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
19
20 #include <functional>
21 #include <type_traits>
22
23
24 template <typename T, typename Expected>
check_equal()25 void check_equal() {
26 static_assert(std::is_same_v<typename std::unwrap_reference<T>::type, Expected>);
27 static_assert(std::is_same_v<typename std::unwrap_reference<T>::type, std::unwrap_reference_t<T>>);
28 }
29
30 template <typename T>
check()31 void check() {
32 check_equal<T, T>();
33 check_equal<T&, T&>();
34 check_equal<T const, T const>();
35 check_equal<T const&, T const&>();
36
37 check_equal<std::reference_wrapper<T>, T&>();
38 check_equal<std::reference_wrapper<T const>, T const&>();
39 }
40
41 struct T { };
42
main()43 int main() {
44 check<T>();
45 check<int>();
46 check<float>();
47
48 check<T*>();
49 check<int*>();
50 check<float*>();
51 }
52