libcxx/test/std/utilities/tuple/tuple.general/ignore.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 // <tuple>
  10
  11 // constexpr unspecified ignore;
  12
  13 // UNSUPPORTED: c++03
  14
  15 #include <cassert>
  16 #include <tuple>
  17 #include <type_traits>
  18
  19 #include "test_macros.h"
  20
  21 constexpr bool test_ignore_constexpr()
  22 {
  23 #if TEST_STD_VER > 11
  24     { // Test that std::ignore provides constexpr converting assignment.
  25         auto& res = (std::ignore = 42);
  26         assert(&res == &std::ignore);
  27     }
  28     { // Test that std::ignore provides constexpr copy/move constructors
  29         auto copy = std::ignore;
  30         auto moved = std::move(copy);
  31         ((void)moved);
  32     }
  33     { // Test that std::ignore provides constexpr copy/move assignment
  34         auto copy = std::ignore;
  35         copy = std::ignore;
  36         auto moved = std::ignore;
  37         moved = std::move(copy);
  38     }
  39 #endif
  40     return true;
  41 }
  42
  43 int main(int, char**) {
  44     {
  45         constexpr auto& ignore_v = std::ignore;
  46         ((void)ignore_v);
  47     }
  48     {
  49         static_assert(test_ignore_constexpr(), "");
  50     }
  51     {
  52         LIBCPP_STATIC_ASSERT(std::is_trivial<decltype(std::ignore)>::value, "");
  53     }
  54
  55   return 0;
  56 }