1 // { dg-do run { target c++14 } }
2
3 // Copyright (C) 2013-2021 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
26 void
test01()27 test01()
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
41 void
test02()42 test02()
43 {
44 struct DefaultConstructible
45 {
46 DefaultConstructible(int i = 0) : value(i) { }
47 int value;
48 };
49
50 DefaultConstructible x = 1;
51 auto old = std::exchange(x, {});
52 VERIFY( x.value == 0 );
53 VERIFY( old.value == 1 );
54 }
55
f(int)56 int f(int) { return 0; }
57
f(double)58 double f(double) { return 0; }
59
60 // Deduce type of overloaded function
61 void
test03()62 test03()
63 {
64 int (*fp)(int);
65 std::exchange(fp, &f);
66 VERIFY( fp != nullptr );
67 }
68
test04()69 void test04()
70 {
71 struct From { };
72 struct To {
73 int value = 0;
74 To() = default;
75 To(const To&) = default;
76 To(const From&) = delete;
77 To& operator=(const From&) { value = 1; return *this; }
78 To& operator=(From&&) { value = 2; return *this; }
79 };
80
81 To t;
82 From f;
83
84 auto prev = std::exchange(t, f);
85 VERIFY( t.value == 1 );
86 VERIFY( prev.value == 0 );
87
88 prev = std::exchange(t, From{});
89 VERIFY( t.value == 2 );
90 VERIFY( prev.value == 1 );
91 }
92
93 int
main()94 main()
95 {
96 test01();
97 test02();
98 test03();
99 test04();
100 return 0;
101 }
102