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... Types> class tuple;
12
13// explicit(see-below) constexpr tuple();
14
15// UNSUPPORTED: c++03
16
17#include <tuple>
18#include <string>
19#include <cassert>
20#include <type_traits>
21
22#include "test_macros.h"
23#include "DefaultOnly.h"
24
25struct NoDefault {
26 NoDefault() = delete;
27 explicit NoDefault(int) { }
28};
29
30struct NoExceptDefault {
31 NoExceptDefault() noexcept = default;
32};
33
34struct ThrowingDefault {
35 ThrowingDefault() { }
36};
37
38struct IllFormedDefault {
39 IllFormedDefault(int x) : value(x) {}
40 template <bool Pred = false>
41 constexpr IllFormedDefault() {
42 static_assert(Pred,
43 "The default constructor should not be instantiated");
44 }
45 int value;
46};
47
48int main(int, char**)
49{
50 {
51 std::tuple<> t;
52 (void)t;
53 }
54 {
55 std::tuple<int> t;
56 assert(std::get<0>(t) == 0);
57 }
58 {
59 std::tuple<int, char*> t;
60 assert(std::get<0>(t) == 0);
61 assert(std::get<1>(t) == nullptr);
62 }
63 {
64 std::tuple<int, char*, std::string> t;
65 assert(std::get<0>(t) == 0);
66 assert(std::get<1>(t) == nullptr);
67 assert(std::get<2>(t) == "");
68 }
69 {
70 std::tuple<int, char*, std::string, DefaultOnly> t;
71 assert(std::get<0>(t) == 0);
72 assert(std::get<1>(t) == nullptr);
73 assert(std::get<2>(t) == "");
74 assert(std::get<3>(t) == DefaultOnly());
75 }
76 {
77 // See bug #21157.
78 static_assert(!std::is_default_constructible<std::tuple<NoDefault>>(), "");
79 static_assert(!std::is_default_constructible<std::tuple<DefaultOnly, NoDefault>>(), "");
80 static_assert(!std::is_default_constructible<std::tuple<NoDefault, DefaultOnly, NoDefault>>(), "");
81 }
82 {
83 static_assert(noexcept(std::tuple<NoExceptDefault>()), "");
84 static_assert(noexcept(std::tuple<NoExceptDefault, NoExceptDefault>()), "");
85
86 static_assert(!noexcept(std::tuple<ThrowingDefault, NoExceptDefault>()), "");
87 static_assert(!noexcept(std::tuple<NoExceptDefault, ThrowingDefault>()), "");
88 static_assert(!noexcept(std::tuple<ThrowingDefault, ThrowingDefault>()), "");
89 }
90 {
91 constexpr std::tuple<> t;
92 (void)t;
93 }
94 {
95 constexpr std::tuple<int> t;
96 assert(std::get<0>(t) == 0);
97 }
98 {
99 constexpr std::tuple<int, char*> t;
100 assert(std::get<0>(t) == 0);
101 assert(std::get<1>(t) == nullptr);
102 }
103 {
104 // Check that the SFINAE on the default constructor is not evaluated when
105 // it isn't needed. If the default constructor is evaluated then this test
106 // should fail to compile.
107 IllFormedDefault v(0);
108 std::tuple<IllFormedDefault> t(v);
109 }
110 {
111 struct Base { };
112 struct Derived : Base { protected: Derived() = default; };
113 static_assert(!std::is_default_constructible<std::tuple<Derived, int> >::value, "");
114 }
115
116 return 0;
117}
118

source code of libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/default.pass.cpp