// Copyright (C) 2019-2020 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 // . // { dg-options "-std=gnu++2a" } // { dg-do compile { target c++2a } } #include #include constexpr int test01(int i, int j) { using T = std::tuple; std::pair p0, p1; std::pair pij(std::piecewise_construct, T(i), T(j)); std::pair pji(std::piecewise_construct, T(j), T(i)); p0.swap(pij); swap(p1, pji); return p0.first - p0.second - p1.first + p1.second; } static_assert( test01(5, 100) == -190 );