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// <tuple>
10
11// template<class U1, class U2>
12// constexpr const tuple& operator=(pair<U1, U2>&& u) const;
13//
14// - sizeof...(Types) is 2,
15// - is_assignable_v<const T1&, U1> is true, and
16// - is_assignable_v<const T2&, U2> is true
17
18// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
19
20#include <cassert>
21#include <tuple>
22#include <type_traits>
23#include <utility>
24
25#include "test_macros.h"
26#include "copy_move_types.h"
27
28// test constraints
29
30// sizeof...(Types) != 2,
31static_assert(std::is_assignable_v<const std::tuple<int&, int&>&, std::pair<int&, int&>&&>);
32static_assert(!std::is_assignable_v<const std::tuple<int&>&, std::pair<int&, int&>&&>);
33static_assert(!std::is_assignable_v<const std::tuple<int&, int&, int&>&, std::pair<int&, int&>&&>);
34
35static_assert(std::is_assignable_v<const std::tuple<AssignableFrom<ConstMoveAssign>, ConstMoveAssign>&,
36 std::pair<ConstMoveAssign, ConstMoveAssign>&&>);
37
38// is_assignable_v<const T1&, U1> is false
39static_assert(!std::is_assignable_v<const std::tuple<AssignableFrom<MoveAssign>, ConstMoveAssign>&,
40 std::pair<MoveAssign, ConstMoveAssign>&&>);
41
42// is_assignable_v<const T2&, U2> is false
43static_assert(!std::is_assignable_v<const std::tuple<AssignableFrom<ConstMoveAssign>, AssignableFrom<MoveAssign>>&,
44 std::tuple<ConstMoveAssign, MoveAssign>&&>);
45
46constexpr bool test() {
47 // reference types
48 {
49 int i1 = 1;
50 int i2 = 2;
51 long j1 = 3;
52 long j2 = 4;
53 std::pair<int&, int&> t1{i1, i2};
54 const std::tuple<long&, long&> t2{j1, j2};
55 t2 = std::move(t1);
56 assert(std::get<0>(t2) == 1);
57 assert(std::get<1>(t2) == 2);
58 }
59
60 // user defined const copy assignment
61 {
62 std::pair<ConstMoveAssign, ConstMoveAssign> t1{1, 2};
63 const std::tuple<AssignableFrom<ConstMoveAssign>, ConstMoveAssign> t2{3, 4};
64 t2 = std::move(t1);
65 assert(std::get<0>(t2).v.val == 1);
66 assert(std::get<1>(t2).val == 2);
67 }
68
69 // make sure the right assignment operator of the type in the tuple is used
70 {
71 std::pair<TracedAssignment, TracedAssignment> t1{};
72 const std::tuple<AssignableFrom<TracedAssignment>, AssignableFrom<TracedAssignment>> t2{};
73 t2 = std::move(t1);
74 assert(std::get<0>(t2).v.constMoveAssign == 1);
75 assert(std::get<1>(t2).v.constMoveAssign == 1);
76 }
77
78 return true;
79}
80
81int main(int, char**) {
82 test();
83
84// gcc cannot have mutable member in constant expression
85#if !defined(TEST_COMPILER_GCC)
86 static_assert(test());
87#endif
88 return 0;
89}
90

source code of libcxx/test/std/utilities/tuple/tuple.tuple/tuple.assign/const_pair_move.pass.cpp