libcxx/test/std/utilities/memory/pointer.traits/ptr.pointer_to.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 // <memory>
  10
  11 // template <class T>
  12 // struct pointer_traits<T*>
  13 // {
  14 //     static pointer pointer_to(<details>) noexcept; // constexpr in C++20
  15 //     ...
  16 // };
  17
  18 #include <memory>
  19 #include <cassert>
  20 #include <type_traits>
  21
  22 #include "test_macros.h"
  23
  24 TEST_CONSTEXPR_CXX20 bool test()
  25 {
  26     // pointer_traits<T*>
  27     {
  28         int i = 0;
  29         static_assert(std::is_same<decltype(std::pointer_traits<int*>::pointer_to(i)), int*>::value, "");
  30         ASSERT_NOEXCEPT(std::pointer_traits<int*>::pointer_to(i));
  31         assert(std::pointer_traits<int*>::pointer_to(i) == &i);
  32     }
  33     // pointer_traits<const T*>
  34     {
  35         int const i = 0;
  36         static_assert(std::is_same<decltype(std::pointer_traits<const int*>::pointer_to(i)), const int*>::value, "");
  37         ASSERT_NOEXCEPT(std::pointer_traits<const int*>::pointer_to(i));
  38         assert(std::pointer_traits<const int*>::pointer_to(i) == &i);
  39     }
  40     // pointer_traits<const T*> with a non-const argument
  41     {
  42         int i = 0;
  43         static_assert(std::is_same<decltype(std::pointer_traits<const int*>::pointer_to(i)), const int*>::value, "");
  44         ASSERT_NOEXCEPT(std::pointer_traits<const int*>::pointer_to(i));
  45         assert(std::pointer_traits<const int*>::pointer_to(i) == &i);
  46     }
  47     return true;
  48 }
  49
  50 int main(int, char**)
  51 {
  52     test();
  53 #if TEST_STD_VER > 17
  54     static_assert(test());
  55 #endif
  56
  57     {
  58         // Check that pointer_traits<void*> is still well-formed, even though it has no pointer_to.
  59         static_assert(std::is_same<std::pointer_traits<void*>::element_type, void>::value, "");
  60         static_assert(std::is_same<std::pointer_traits<const void*>::element_type, const void>::value, "");
  61         static_assert(std::is_same<std::pointer_traits<volatile void*>::element_type, volatile void>::value, "");
  62     }
  63
  64     return 0;
  65 }