1// { dg-options "-std=gnu++14" } 2 3// Copyright (C) 2013-2015 Free Software Foundation, Inc. 4// 5// This file is part of the GNU ISO C++ Library. This library is free 6// software; you can redistribute it and/or modify it under the 7// terms of the GNU General Public License as published by the 8// Free Software Foundation; either version 3, or (at your option) 9// any later version. 10 11// This library is distributed in the hope that it will be useful, 12// but WITHOUT ANY WARRANTY; without even the implied warranty of 13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14// GNU General Public License for more details. 15 16// You should have received a copy of the GNU General Public License along 17// with this library; see the file COPYING3. If not see 18// <http://www.gnu.org/licenses/>. 19 20// 20.2.3 exchange [utility.exchange] 21 22#include <utility> 23#include <type_traits> 24#include <testsuite_hooks.h> 25 26void 27test01() 28{ 29 const unsigned val = 4; 30 int i = 1; 31 auto prev = std::exchange(i, val); 32 static_assert( std::is_same<decltype(prev), int>::value, "return type" ); 33 VERIFY( i == 4 ); 34 VERIFY( prev == 1 ); 35 prev = std::exchange(i, 3); 36 VERIFY( i == 3 ); 37 VERIFY( prev == 4 ); 38} 39 40// Default construction from empty braces 41void 42test02() 43{ 44 bool test __attribute__((unused)) = true; 45 46 struct DefaultConstructible 47 { 48 DefaultConstructible(int i = 0) : value(i) { } 49 int value; 50 }; 51 52 DefaultConstructible x = 1; 53 auto old = std::exchange(x, {}); 54 VERIFY( x.value == 0 ); 55 VERIFY( old.value == 1 ); 56} 57 58int f(int) { return 0; } 59 60double f(double) { return 0; } 61 62// Deduce type of overloaded function 63void 64test03() 65{ 66 bool test __attribute__((unused)) = true; 67 68 int (*fp)(int); 69 std::exchange(fp, &f); 70 VERIFY( fp != nullptr ); 71} 72 73void test04() 74{ 75 struct From { }; 76 struct To { 77 int value = 0; 78 To() = default; 79 To(const To&) = default; 80 To(const From&) = delete; 81 To& operator=(const From&) { value = 1; return *this; } 82 To& operator=(From&&) { value = 2; return *this; } 83 }; 84 85 To t; 86 From f; 87 88 auto prev = std::exchange(t, f); 89 VERIFY( t.value == 1 ); 90 VERIFY( prev.value == 0 ); 91 92 prev = std::exchange(t, From{}); 93 VERIFY( t.value == 2 ); 94 VERIFY( prev.value == 1 ); 95} 96 97int 98main() 99{ 100 test01(); 101 test02(); 102 test03(); 103 test04(); 104 return 0; 105} 106