1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 // <functional> 10 // 11 // template <class T> 12 // struct unwrap_ref_decay; 13 // 14 // template <class T> 15 // using unwrap_ref_decay_t = typename unwrap_ref_decay<T>::type; 16 17 // UNSUPPORTED: c++98, c++03, c++11, c++14, c++17 18 19 #include <functional> 20 #include <type_traits> 21 22 23 template <typename T, typename Result> 24 void check() { 25 static_assert(std::is_same_v<typename std::unwrap_ref_decay<T>::type, Result>); 26 static_assert(std::is_same_v<typename std::unwrap_ref_decay<T>::type, std::unwrap_ref_decay_t<T>>); 27 } 28 29 struct T { }; 30 31 int main() { 32 check<T, T>(); 33 check<T&, T>(); 34 check<T const, T>(); 35 check<T const&, T>(); 36 check<T*, T*>(); 37 check<T const*, T const*>(); 38 check<T[3], T*>(); 39 check<T const [3], T const*>(); 40 check<T (), T (*)()>(); 41 check<T (int) const, T (int) const>(); 42 check<T (int) &, T (int) &>(); 43 check<T (int) &&, T (int) &&>(); 44 45 check<std::reference_wrapper<T>, T&>(); 46 check<std::reference_wrapper<T>&, T&>(); 47 check<std::reference_wrapper<T const>, T const&>(); 48 check<std::reference_wrapper<T const>&, T const&>(); 49 check<std::reference_wrapper<T*>, T*&>(); 50 check<std::reference_wrapper<T*>&, T*&>(); 51 check<std::reference_wrapper<T const*>, T const*&>(); 52 check<std::reference_wrapper<T const*>&, T const*&>(); 53 check<std::reference_wrapper<T[3]>, T (&)[3]>(); 54 check<std::reference_wrapper<T[3]>&, T (&)[3]>(); 55 check<std::reference_wrapper<T ()>, T (&)()>(); 56 check<std::reference_wrapper<T ()>&, T (&)()>(); 57 } 58