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, c++17
10
11// type_traits
12// common_reference
13
14#include <tuple>
15#include <type_traits>
16#include <utility>
17
18#include "test_macros.h"
19
20template <class T>
21constexpr bool has_type = requires {
22 typename T::type;
23};
24
25// A slightly simplified variation of std::tuple
26template <class...>
27struct UserTuple {};
28
29template <class, class, class>
30struct Tuple_helper {};
31template <class... Ts, class... Us>
32struct Tuple_helper<std::void_t<std::common_reference_t<Ts, Us>...>, UserTuple<Ts...>, UserTuple<Us...> > {
33 using type = UserTuple<std::common_reference_t<Ts, Us>...>;
34};
35
36template <class... Ts, class... Us, template <class> class TQual, template <class> class UQual>
37struct std::basic_common_reference< ::UserTuple<Ts...>, ::UserTuple<Us...>, TQual, UQual>
38 : ::Tuple_helper<void, UserTuple<TQual<Ts>...>, UserTuple<UQual<Us>...> > {};
39
40struct X2 {};
41struct Y2 {};
42struct Z2 {};
43
44template <>
45struct std::common_type<X2, Y2> {
46 using type = Z2;
47};
48template <>
49struct std::common_type<Y2, X2> {
50 using type = Z2;
51};
52
53// (6.1)
54// -- If sizeof...(T) is zero, there shall be no member type.
55static_assert(!has_type<std::common_reference<> >);
56
57// (6.2)
58// -- Otherwise, if sizeof...(T) is one, let T0 denote the sole type in the
59// pack T. The member typedef type shall denote the same type as T0.
60static_assert(std::is_same_v<std::common_reference_t<void>, void>);
61static_assert(std::is_same_v<std::common_reference_t<int>, int>);
62static_assert(std::is_same_v<std::common_reference_t<int&>, int&>);
63static_assert(std::is_same_v<std::common_reference_t<int&&>, int&&>);
64static_assert(std::is_same_v<std::common_reference_t<int const>, int const>);
65static_assert(std::is_same_v<std::common_reference_t<int const&>, int const&>);
66static_assert(std::is_same_v<std::common_reference_t<int const&&>, int const&&>);
67static_assert(std::is_same_v<std::common_reference_t<int volatile[]>, int volatile[]>);
68static_assert(std::is_same_v<std::common_reference_t<int volatile (&)[]>, int volatile (&)[]>);
69static_assert(std::is_same_v<std::common_reference_t<int volatile (&&)[]>, int volatile (&&)[]>);
70static_assert(std::is_same_v<std::common_reference_t<void (&)()>, void (&)()>);
71static_assert(std::is_same_v<std::common_reference_t<void (&&)()>, void (&&)()>);
72
73// (6.3)
74// -- Otherwise, if sizeof...(T) is two, let T1 and T2 denote the two types in
75// the pack T. Then
76// (6.3.1)
77// -- If T1 and T2 are reference types and COMMON_REF(T1, T2) is well-formed,
78// then the member typedef type denotes that type.
79struct B {};
80struct D : B {};
81static_assert(std::is_same_v<std::common_reference_t<B&, D&>, B&>);
82static_assert(std::is_same_v<std::common_reference_t<B const&, D&>, B const&>);
83static_assert(std::is_same_v<std::common_reference_t<B&, D const&>, B const&>);
84static_assert(std::is_same_v<std::common_reference_t<B&, D const&, D&>, B const&>);
85static_assert(std::is_same_v<std::common_reference_t<B&, D&, B&, D&>, B&>);
86
87static_assert(std::is_same_v<std::common_reference_t<B&&, D&&>, B&&>);
88static_assert(std::is_same_v<std::common_reference_t<B const&&, D&&>, B const&&>);
89static_assert(std::is_same_v<std::common_reference_t<B&&, D const&&>, B const&&>);
90static_assert(std::is_same_v<std::common_reference_t<B&, D&&>, B const&>);
91static_assert(std::is_same_v<std::common_reference_t<B&, D const&&>, B const&>);
92static_assert(std::is_same_v<std::common_reference_t<B const&, D&&>, B const&>);
93
94static_assert(std::is_same_v<std::common_reference_t<B&&, D&>, B const&>);
95static_assert(std::is_same_v<std::common_reference_t<B&&, D const&>, B const&>);
96static_assert(std::is_same_v<std::common_reference_t<B const&&, D&>, B const&>);
97
98static_assert(std::is_same_v<std::common_reference_t<int const&, int volatile&>, int const volatile&>);
99static_assert(std::is_same_v<std::common_reference_t<int const volatile&&, int volatile&&>, int const volatile&&>);
100
101static_assert(std::is_same_v<std::common_reference_t<int (&)[10], int (&&)[10]>, int const (&)[10]>);
102static_assert(std::is_same_v<std::common_reference_t<int const (&)[10], int volatile (&)[10]>, int const volatile (&)[10]>);
103
104// (6.3.2)
105// -- Otherwise, if basic_common_reference<remove_cvref_t<T1>,
106// remove_cvref_t<T2>, XREF(T1), XREF(T2)>::type is well-formed, then the
107// member typedef type denotes that type.
108static_assert(std::is_same_v<std::common_reference_t<const UserTuple<int, short>&, UserTuple<int&, short volatile&>>,
109 UserTuple<const int&, const volatile short&>>);
110
111static_assert(std::is_same_v<std::common_reference_t<volatile UserTuple<int, short>&, const UserTuple<int, short>&>,
112 const volatile UserTuple<int, short>&>);
113
114// (6.3.3)
115// -- Otherwise, if COND_RES(T1, T2) is well-formed, then the member typedef
116// type denotes that type.
117static_assert(std::is_same_v<std::common_reference_t<void, void>, void>);
118static_assert(std::is_same_v<std::common_reference_t<int, short>, int>);
119static_assert(std::is_same_v<std::common_reference_t<int, short&>, int>);
120static_assert(std::is_same_v<std::common_reference_t<int&, short&>, int>);
121static_assert(std::is_same_v<std::common_reference_t<int&, short>, int>);
122
123// tricky volatile reference case
124static_assert(std::is_same_v<std::common_reference_t<int&&, int volatile&>, int>);
125static_assert(std::is_same_v<std::common_reference_t<int volatile&, int&&>, int>);
126
127static_assert(std::is_same_v<std::common_reference_t<int (&)[10], int (&)[11]>, int*>);
128
129// https://github.com/ericniebler/stl2/issues/338
130struct MyIntRef {
131 MyIntRef(int&);
132};
133static_assert(std::is_same_v<std::common_reference_t<int&, MyIntRef>, MyIntRef>);
134
135// (6.3.4)
136// -- Otherwise, if common_type_t<T1, T2> is well-formed, then the member
137// typedef type denotes that type.
138struct moveonly {
139 moveonly() = default;
140 moveonly(moveonly&&) = default;
141 moveonly& operator=(moveonly&&) = default;
142};
143struct moveonly2 : moveonly {};
144
145static_assert(std::is_same_v<std::common_reference_t<moveonly const&, moveonly>, moveonly>);
146static_assert(std::is_same_v<std::common_reference_t<moveonly2 const&, moveonly>, moveonly>);
147static_assert(std::is_same_v<std::common_reference_t<moveonly const&, moveonly2>, moveonly>);
148
149static_assert(std::is_same_v<std::common_reference_t<X2&, Y2 const&>, Z2>);
150
151// (6.3.5)
152// -- Otherwise, there shall be no member type.
153static_assert(!has_type<std::common_reference<volatile UserTuple<short>&, const UserTuple<int, short>&> >);
154
155// (6.4)
156// -- Otherwise, if sizeof...(T) is greater than two, let T1, T2, and Rest,
157// respectively, denote the first, second, and (pack of) remaining types
158// comprising T. Let C be the type common_reference_t<T1, T2>. Then:
159// (6.4.1)
160// -- If there is such a type C, the member typedef type shall denote the
161// same type, if any, as common_reference_t<C, Rest...>.
162static_assert(std::is_same_v<std::common_reference_t<int, int, int>, int>);
163static_assert(std::is_same_v<std::common_reference_t<int&&, int const&, int volatile&>, int const volatile&>);
164static_assert(std::is_same_v<std::common_reference_t<int&&, int const&, float&>, float>);
165
166// (6.4.2)
167// -- Otherwise, there shall be no member type.
168static_assert(!has_type<std::common_reference<int, short, int, char*> >);
169
170#if TEST_STD_VER > 20
171static_assert(std::is_same_v<std::common_reference_t<std::tuple<int, int>>, std::tuple<int, int>>);
172static_assert(std::is_same_v<std::common_reference_t<std::tuple<int, long>, std::tuple<long, int>>, std::tuple<long, long>>);
173static_assert(std::is_same_v<std::common_reference_t<std::tuple<int&, const int&>, std::tuple<const int&, int>>,
174 std::tuple<const int&, int>>);
175static_assert(std::is_same_v<std::common_reference_t<std::tuple<int&, volatile int&>, std::tuple<volatile int&, int>>,
176 std::tuple<volatile int&, int>>);
177static_assert(std::is_same_v<std::common_reference_t<std::tuple<int&, const volatile int&>, std::tuple<const volatile int&, int>>,
178 std::tuple<const volatile int&, int>>);
179static_assert(!has_type<std::common_reference_t<std::tuple<const int&, volatile int&>, std::tuple<volatile int&, const int&>>>);
180
181static_assert(std::is_same_v<std::common_reference_t<std::tuple<int, X2>, std::tuple<int, Y2>>, std::tuple<int, Z2>>);
182static_assert(std::is_same_v<std::common_reference_t<std::tuple<int, X2>, std::tuple<int, Y2>>, std::tuple<int, Z2>>);
183static_assert(!has_type<std::common_reference<std::tuple<int, const X2>, std::tuple<float, const Z2>>>);
184static_assert(!has_type<std::common_reference<std::tuple<int, X2>, std::tuple<float, Z2>>>);
185static_assert(!has_type<std::common_reference<std::tuple<int, X2>, int, X2>>);
186
187struct A {};
188template <template<class> class TQual, template<class> class UQual>
189struct std::basic_common_reference<A, std::tuple<B>, TQual, UQual> {
190 using type = tuple<UQual<B>>;
191};
192
193static_assert(std::is_same_v<std::common_reference_t<A, std::tuple<B>, std::tuple<D>>, std::tuple<B>>);
194
195
196static_assert(std::is_same_v<std::common_reference_t<std::pair<int, int>>,
197 std::pair<int, int>>);
198static_assert(std::is_same_v<std::common_reference_t<std::pair<int, long>, std::pair<long, int>>,
199 std::pair<long, long>>);
200static_assert(std::is_same_v<std::common_reference_t<std::pair<int&, const int&>, std::pair<const int&, int>>,
201 std::pair<const int&, int>>);
202static_assert(std::is_same_v<std::common_reference_t<std::pair<int&, volatile int&>, std::pair<volatile int&, int>>,
203 std::pair<volatile int&, int>>);
204static_assert(std::is_same_v<std::common_reference_t<std::pair<int&, const volatile int&>, std::pair<const volatile int&, int>>,
205 std::pair<const volatile int&, int>>);
206static_assert(!has_type<std::common_reference_t<std::pair<const int&, volatile int&>,
207 std::pair<volatile int&, const int&>>>);
208
209static_assert(std::is_same_v<std::common_reference_t<std::pair<int, X2>, std::pair<int, Y2>>, std::pair<int, Z2>>);
210static_assert(std::is_same_v<std::common_reference_t<std::pair<int, X2>, std::pair<int, Y2>>, std::pair<int, Z2>>);
211static_assert(!has_type<std::common_reference<std::pair<int, const X2>, std::pair<float, const Z2>>>);
212static_assert(!has_type<std::common_reference<std::pair<int, X2>, std::pair<float, Z2>>>);
213static_assert(!has_type<std::common_reference<std::pair<int, X2>, int, X2>>);
214#endif
215

source code of libcxx/test/std/utilities/meta/meta.trans/meta.trans.other/common_reference.compile.pass.cpp