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8d9254fc | 1 | // Copyright (C) 2019-2020 Free Software Foundation, Inc. |
0f8b14ee JW |
2 | // |
3 | // This file is part of the GNU ISO C++ Library. This library is free | |
4 | // software; you can redistribute it and/or modify it under the | |
5 | // terms of the GNU General Public License as published by the | |
6 | // Free Software Foundation; either version 3, or (at your option) | |
7 | // any later version. | |
8 | // | |
9 | // This library is distributed in the hope that it will be useful, | |
10 | // but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | // GNU General Public License for more details. | |
13 | // | |
14 | // You should have received a copy of the GNU General Public License along | |
15 | // with this library; see the file COPYING3. If not see | |
16 | // <http://www.gnu.org/licenses/>. | |
17 | ||
18 | // { dg-options "-std=gnu++2a" } | |
19 | // { dg-do compile { target c++2a } } | |
20 | ||
21 | #include <type_traits> | |
22 | ||
23 | template<typename T, typename = void> | |
24 | struct has_type : std::false_type { }; | |
25 | ||
26 | template<typename T> | |
27 | struct has_type<T, std::void_t<typename T::type>> : std::true_type { }; | |
28 | ||
29 | template<typename... T> | |
30 | constexpr bool | |
31 | has_common_ref() | |
32 | { | |
33 | return has_type<std::common_reference<T...>>::value; | |
34 | } | |
35 | ||
36 | using std::is_same_v; | |
37 | using std::common_reference_t; | |
38 | ||
39 | void test01() | |
40 | { | |
41 | ||
42 | static_assert( !has_common_ref<>() ); | |
43 | static_assert( !has_common_ref<char(*)(), int(*)()>() ); | |
44 | static_assert( !has_common_ref<void*, int>() ); | |
45 | ||
46 | static_assert( is_same_v<common_reference_t<int>, int> ); | |
47 | static_assert( is_same_v<common_reference_t<int&>, int&> ); | |
48 | static_assert( is_same_v<common_reference_t<void>, void> ); | |
49 | static_assert( is_same_v<common_reference_t<const void>, const void> ); | |
50 | static_assert( is_same_v<common_reference_t<const void, void>, void> ); | |
51 | static_assert( is_same_v<common_reference_t<void(*const)(), void(*)()>, void(*)()> ); | |
52 | static_assert( is_same_v<common_reference_t<int, int>, int> ); | |
53 | static_assert( is_same_v<common_reference_t<int&, int>, int> ); | |
54 | static_assert( is_same_v<common_reference_t<int, int&>, int> ); | |
55 | static_assert( is_same_v<common_reference_t<int&&, int>, int> ); | |
56 | static_assert( is_same_v<common_reference_t<int&, int&>, int&> ); | |
57 | static_assert( is_same_v<common_reference_t<int&, int&&>, const int&> ); | |
58 | static_assert( is_same_v<common_reference_t<int&&, int&>, const int&> ); | |
59 | static_assert( is_same_v<common_reference_t<int&&, int&&>, int&&> ); | |
60 | static_assert( is_same_v<common_reference_t<int&&, const int&&>, const int&&> ); | |
61 | static_assert( is_same_v<common_reference_t<int&, int&, int&&>, const int&> ); | |
62 | static_assert( is_same_v<common_reference_t<int&&, int&, int&>, const int&> ); | |
63 | static_assert( is_same_v<common_reference_t<char&, int&>, int> ); | |
64 | static_assert( is_same_v<common_reference_t<long&, int&>, long> ); | |
65 | } | |
66 | ||
67 | struct A { }; | |
68 | struct B { }; | |
69 | struct C { }; | |
70 | ||
71 | template<template<typename> class AQual, template<typename> class BQual> | |
72 | struct std::basic_common_reference<A, B, AQual, BQual> | |
73 | { | |
74 | using type = BQual<AQual<C>>; | |
75 | }; | |
76 | ||
77 | static_assert( is_same_v<common_reference_t<A, B>, C> ); | |
78 | static_assert( is_same_v<common_reference_t<A&, B>, C&> ); | |
79 | static_assert( is_same_v<common_reference_t<A&, const B>, C&> ); | |
80 | static_assert( is_same_v<common_reference_t<const A, B&>, const C&> ); | |
81 | static_assert( is_same_v<common_reference_t<const A&, B&&>, const C&> ); | |
82 | static_assert( is_same_v<common_reference_t<const A, B&&>, const C&&> ); | |
83 | ||
84 | struct D { }; | |
85 | struct E { }; | |
86 | struct F { }; | |
87 | ||
88 | template<> struct std::common_type<D, E> { using type = F; }; | |
89 | ||
90 | static_assert( is_same_v<common_reference_t<D, E>, F> ); | |
91 | static_assert( is_same_v<common_reference_t<D&, E>, F> ); | |
92 | static_assert( is_same_v<common_reference_t<D&, E&&>, F> ); |