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

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