libcxx/test/std/utilities/function.objects/refwrap/unwrap_reference.pass.cpp

   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_reference;
  13 //
  14 // template <class T>
  15 // using unwrap_reference_t = typename unwrap_reference<T>::type;
  16
  17 // UNSUPPORTED: c++03, c++11, c++14, c++17
  18
  19 #include <functional>
  20 #include <type_traits>
  21
  22 #include "test_macros.h"
  23
  24
  25 template <typename T, typename Expected>
  26 void check_equal() {
  27   static_assert(std::is_same_v<typename std::unwrap_reference<T>::type, Expected>);
  28   static_assert(std::is_same_v<typename std::unwrap_reference<T>::type, std::unwrap_reference_t<T>>);
  29 }
  30
  31 template <typename T>
  32 void check() {
  33   check_equal<T, T>();
  34   check_equal<T&, T&>();
  35   check_equal<T const, T const>();
  36   check_equal<T const&, T const&>();
  37
  38   check_equal<std::reference_wrapper<T>, T&>();
  39   check_equal<std::reference_wrapper<T const>, T const&>();
  40 }
  41
  42 struct T { };
  43
  44 int main(int, char**) {
  45   check<T>();
  46   check<int>();
  47   check<float>();
  48
  49   check<T*>();
  50   check<int*>();
  51   check<float*>();
  52
  53   return 0;
  54 }