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
10
11// <utility>
12
13// Test that the constructors offered by std::pair are formulated
14// so they're compatible with implicit deduction guides, or if that's not
15// possible that they provide explicit guides to make it work.
16
17#include <utility>
18#include <memory>
19#include <string>
20#include <cassert>
21
22#include "test_macros.h"
23#include "archetypes.h"
24
25
26// Overloads
27// ---------------
28// (1) pair(const T1&, const T2&) -> pair<T1, T2>
29// (2) explicit pair(const T1&, const T2&) -> pair<T1, T2>
30// (3) pair(pair const& t) -> decltype(t)
31// (4) pair(pair&& t) -> decltype(t)
32// (5) pair(pair<U1, U2> const&) -> pair<U1, U2>
33// (6) explicit pair(pair<U1, U2> const&) -> pair<U1, U2>
34// (7) pair(pair<U1, U2> &&) -> pair<U1, U2>
35// (8) explicit pair(pair<U1, U2> &&) -> pair<U1, U2>
36int main(int, char**)
37{
38 using E = ExplicitTestTypes::TestType;
39 static_assert(!std::is_convertible<E const&, E>::value, "");
40 { // Testing (1)
41 int const x = 42;
42 std::pair t1("abc", x);
43 ASSERT_SAME_TYPE(decltype(t1), std::pair<const char*, int>);
44 }
45 { // Testing (2)
46 std::pair p1(E{}, 42);
47 ASSERT_SAME_TYPE(decltype(p1), std::pair<E, int>);
48
49 const E t{};
50 std::pair p2(t, E{});
51 ASSERT_SAME_TYPE(decltype(p2), std::pair<E, E>);
52 }
53 { // Testing (3, 5)
54 std::pair<double, decltype(nullptr)> const p(0.0, nullptr);
55 std::pair p1(p);
56 ASSERT_SAME_TYPE(decltype(p1), std::pair<double, decltype(nullptr)>);
57 }
58 { // Testing (3, 6)
59 std::pair<E, decltype(nullptr)> const p(E{}, nullptr);
60 std::pair p1(p);
61 ASSERT_SAME_TYPE(decltype(p1), std::pair<E, decltype(nullptr)>);
62 }
63 { // Testing (4, 7)
64 std::pair<std::string, void*> p("abc", nullptr);
65 std::pair p1(std::move(p));
66 ASSERT_SAME_TYPE(decltype(p1), std::pair<std::string, void*>);
67 }
68 { // Testing (4, 8)
69 std::pair<std::string, E> p("abc", E{});
70 std::pair p1(std::move(p));
71 ASSERT_SAME_TYPE(decltype(p1), std::pair<std::string, E>);
72 }
73
74 return 0;
75}
76

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