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// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
10
11// <utility>
12
13// template <class T1, class T2> struct pair
14
15// template <class U1, class U2>
16// constexpr explicit(see below) pair(const pair<U1, U2>&& p);
17
18#include <cassert>
19#include <utility>
20
21#include "copy_move_types.h"
22#include "test_macros.h"
23
24// Constraints:
25// is_constructible_v<T1, decltype(get<0>(FWD(p)))> is true and
26// is_constructible_v<T2, decltype(get<1>(FWD(p)))> is true.
27struct X {};
28struct Y {};
29struct NotConvertibleToXorY {};
30
31static_assert(std::is_constructible_v<std::pair<X, Y>, const std::pair<X, Y>&&>);
32static_assert(!std::is_constructible_v<std::pair<X, Y>, const std::pair<NotConvertibleToXorY, Y>&&>);
33static_assert(!std::is_constructible_v<std::pair<X, Y>, const std::pair<X, NotConvertibleToXorY>&&>);
34static_assert(!std::is_constructible_v<std::pair<X, Y>, const std::pair<NotConvertibleToXorY, NotConvertibleToXorY>&&>);
35
36// The expression inside explicit is equivalent to:
37// !is_convertible_v<decltype(get<0>(FWD(p))), first_type> ||
38// !is_convertible_v<decltype(get<1>(FWD(p))), second_type>.
39// clang-format off
40static_assert( std::is_convertible_v<const std::pair<X, Y>&&,
41 std::pair<ConvertibleFrom<X>, ConvertibleFrom<Y>>>);
42static_assert(!std::is_convertible_v<const std::pair<X, Y>&&,
43 std::pair<ConvertibleFrom<X>, ExplicitConstructibleFrom<Y>>>);
44static_assert(!std::is_convertible_v<const std::pair<X, Y>&&,
45 std::pair<ExplicitConstructibleFrom<X>, ConvertibleFrom<Y>>>);
46static_assert(!std::is_convertible_v<const std::pair<X, Y>&&,
47 std::pair<ExplicitConstructibleFrom<X>, ExplicitConstructibleFrom<Y>>>);
48// clang-format on
49
50constexpr bool test() {
51 // simple case: init pair<const T&&, const U&&> from const pair<T, U>&&
52 {
53 const std::pair<int, int> p1{1, 2};
54 std::pair<const int&&, const int&&> p2{std::move(p1)};
55 assert(&(p2.first) == &(p1.first));
56 assert(&(p2.second) == &(p1.second));
57 }
58
59 // test implicit conversions.
60 {
61 const std::pair<ConstMove, int> p1{1, 2};
62 std::pair<ConvertibleFrom<ConstMove>, ConvertibleFrom<int>> p2 = std::move(p1);
63 assert(p2.first.v.val == 1);
64 assert(p2.second.v == 2);
65 }
66
67 // test explicit conversions.
68 {
69 const std::pair<ConstMove, int> p1{1, 2};
70 std::pair<ExplicitConstructibleFrom<ConstMove>, ExplicitConstructibleFrom<int>> p2{std::move(p1)};
71 assert(p2.first.v.val == 1);
72 assert(p2.second.v == 2);
73 }
74
75 // test correct constructors of underlying types are called
76 {
77 const std::pair<TracedCopyMove, TracedCopyMove> p1{};
78 std::pair<ConvertibleFrom<TracedCopyMove>, ConvertibleFrom<TracedCopyMove>> p2{std::move(p1)};
79 assert(constMoveCtrCalled(p2.first.v));
80 assert(constMoveCtrCalled(p2.second.v));
81 }
82
83 return true;
84}
85
86int main(int, char**) {
87 test();
88 static_assert(test());
89 return 0;
90}
91

source code of libcxx/test/std/utilities/utility/pairs/pairs.pair/ctor.pair_U_V_const_move.pass.cpp