| // Copyright (C) 2019-2023 Free Software Foundation, Inc. |
| // |
| // This file is part of the GNU ISO C++ Library. This library is free |
| // software; you can redistribute it and/or modify it under the |
| // terms of the GNU General Public License as published by the |
| // Free Software Foundation; either version 3, or (at your option) |
| // any later version. |
| |
| // This library is distributed in the hope that it will be useful, |
| // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| // GNU General Public License for more details. |
| |
| // You should have received a copy of the GNU General Public License along |
| // with this library; see the file COPYING3. If not see |
| // <http://www.gnu.org/licenses/>. |
| |
| // { dg-options "-std=gnu++2a" } |
| // { dg-do compile { target c++2a } } |
| |
| #include <utility> |
| |
| #ifndef __cpp_lib_constexpr_algorithms |
| # error "Feature test macro for constexpr std::exchange is missing in <utility>" |
| #elif __cpp_lib_constexpr_algorithms < 201806L |
| # error "Feature test macro for constexpr std::exchange has wrong value in <utility>" |
| #endif |
| |
| constexpr bool |
| test() |
| { |
| constexpr double e_v = 2.71828182846; |
| double e = e_v; |
| constexpr double pi_v = 3.14159265359; |
| const auto x = std::exchange(e, pi_v); |
| |
| return x == e_v && e == pi_v; |
| } |
| |
| static_assert(test()); |
