1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
|
// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++03, c++11, c++14
// Throwing bad_variant_access is supported starting in macosx10.13
// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11|12}} && !no-exceptions
// <variant>
// template <class ...Types> class variant;
// template <size_t I, class ...Args>
// variant_alternative_t<I, variant<Types...>>& emplace(Args&&... args);
#include <cassert>
#include <string>
#include <type_traits>
#include <variant>
#include "archetypes.h"
#include "test_convertible.h"
#include "test_macros.h"
#include "variant_test_helpers.h"
template <class Var, size_t I, class... Args>
constexpr auto test_emplace_exists_imp(int) -> decltype(
std::declval<Var>().template emplace<I>(std::declval<Args>()...), true) {
return true;
}
template <class, size_t, class...>
constexpr auto test_emplace_exists_imp(long) -> bool {
return false;
}
template <class Var, size_t I, class... Args> constexpr bool emplace_exists() {
return test_emplace_exists_imp<Var, I, Args...>(0);
}
void test_emplace_sfinae() {
{
using V = std::variant<int, void *, const void *, TestTypes::NoCtors>;
static_assert(emplace_exists<V, 0>(), "");
static_assert(emplace_exists<V, 0, int>(), "");
static_assert(!emplace_exists<V, 0, decltype(nullptr)>(),
"cannot construct");
static_assert(emplace_exists<V, 1, decltype(nullptr)>(), "");
static_assert(emplace_exists<V, 1, int *>(), "");
static_assert(!emplace_exists<V, 1, const int *>(), "");
static_assert(!emplace_exists<V, 1, int>(), "cannot construct");
static_assert(emplace_exists<V, 2, const int *>(), "");
static_assert(emplace_exists<V, 2, int *>(), "");
static_assert(!emplace_exists<V, 3>(), "cannot construct");
}
#if !defined(TEST_VARIANT_HAS_NO_REFERENCES)
{
using V = std::variant<int, int &, const int &, int &&, TestTypes::NoCtors>;
static_assert(emplace_exists<V, 0>(), "");
static_assert(emplace_exists<V, 0, int>(), "");
static_assert(emplace_exists<V, 0, long long>(), "");
static_assert(!emplace_exists<V, 0, int, int>(), "too many args");
static_assert(emplace_exists<V, 1, int &>(), "");
static_assert(!emplace_exists<V, 1>(), "cannot default construct ref");
static_assert(!emplace_exists<V, 1, const int &>(), "cannot bind ref");
static_assert(!emplace_exists<V, 1, int &&>(), "cannot bind ref");
static_assert(emplace_exists<V, 2, int &>(), "");
static_assert(emplace_exists<V, 2, const int &>(), "");
static_assert(emplace_exists<V, 2, int &&>(), "");
static_assert(!emplace_exists<V, 2, void *>(),
"not constructible from void*");
static_assert(emplace_exists<V, 3, int>(), "");
static_assert(!emplace_exists<V, 3, int &>(), "cannot bind ref");
static_assert(!emplace_exists<V, 3, const int &>(), "cannot bind ref");
static_assert(!emplace_exists<V, 3, const int &&>(), "cannot bind ref");
static_assert(!emplace_exists<V, 4>(), "no ctors");
}
#endif
}
void test_basic() {
{
using V = std::variant<int>;
V v(42);
auto& ref1 = v.emplace<0>();
static_assert(std::is_same_v<int&, decltype(ref1)>, "");
assert(std::get<0>(v) == 0);
assert(&ref1 == &std::get<0>(v));
auto& ref2 = v.emplace<0>(42);
static_assert(std::is_same_v<int&, decltype(ref2)>, "");
assert(std::get<0>(v) == 42);
assert(&ref2 == &std::get<0>(v));
}
{
using V =
std::variant<int, long, const void *, TestTypes::NoCtors, std::string>;
const int x = 100;
V v(std::in_place_index<0>, -1);
// default emplace a value
auto& ref1 = v.emplace<1>();
static_assert(std::is_same_v<long&, decltype(ref1)>, "");
assert(std::get<1>(v) == 0);
assert(&ref1 == &std::get<1>(v));
auto& ref2 = v.emplace<2>(&x);
static_assert(std::is_same_v<const void*&, decltype(ref2)>, "");
assert(std::get<2>(v) == &x);
assert(&ref2 == &std::get<2>(v));
// emplace with multiple args
auto& ref3 = v.emplace<4>(3u, 'a');
static_assert(std::is_same_v<std::string&, decltype(ref3)>, "");
assert(std::get<4>(v) == "aaa");
assert(&ref3 == &std::get<4>(v));
}
#if !defined(TEST_VARIANT_HAS_NO_REFERENCES)
{
using V = std::variant<int, long, const int &, int &&, TestTypes::NoCtors,
std::string>;
const int x = 100;
int y = 42;
int z = 43;
V v(std::in_place_index<0>, -1);
// default emplace a value
auto& ref1 = v.emplace<1>();
static_assert(std::is_same_v<long&, decltype(ref1)>, "");
assert(std::get<1>(v) == 0);
assert(&ref1 == &std::get<1>(v));
// emplace a reference
auto& ref2 = v.emplace<2>(x);
static_assert(std::is_same_v<&, decltype(ref)>, "");
assert(&std::get<2>(v) == &x);
assert(&ref2 == &std::get<2>(v));
// emplace an rvalue reference
auto& ref3 = v.emplace<3>(std::move(y));
static_assert(std::is_same_v<&, decltype(ref)>, "");
assert(&std::get<3>(v) == &y);
assert(&ref3 == &std::get<3>(v));
// re-emplace a new reference over the active member
auto& ref4 = v.emplace<3>(std::move(z));
static_assert(std::is_same_v<&, decltype(ref)>, "");
assert(&std::get<3>(v) == &z);
assert(&ref4 == &std::get<3>(v));
// emplace with multiple args
auto& ref5 = v.emplace<5>(3u, 'a');
static_assert(std::is_same_v<std::string&, decltype(ref5)>, "");
assert(std::get<5>(v) == "aaa");
assert(&ref5 == &std::get<5>(v));
}
#endif
}
int main(int, char**) {
test_basic();
test_emplace_sfinae();
return 0;
}
|
