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>
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>
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 
43 int main() {
44   check<T>();
45   check<int>();
46   check<float>();
47 
48   check<T*>();
49   check<int*>();
50   check<float*>();
51 }
52