1 // Copyright (C) 2016-2019 Free Software Foundation, Inc.
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-do compile { target c++11 } }
19
20 #include <memory>
21
22 template<typename T, typename Args, typename = void>
23 struct resettable
24 : std::false_type
25 { };
26
27 template<typename... T> struct type_list { };
28
29 template<typename T, typename... Args>
30 using reset_result
31 = decltype(std::shared_ptr<T>{}.reset(std::declval<Args>()...));
32
33 template<typename T, typename... Args>
34 struct resettable<T, type_list<Args...>, reset_result<T, Args...>>
35 : std::true_type
36 { };
37
38 template<typename T, typename... Args>
can_reset()39 constexpr bool can_reset()
40 { return resettable<T, type_list<Args...>>::value; }
41
42 template<typename T>
43 struct Deleter {
44 void operator()(T*) const;
45 };
46
47 template<typename T>
48 using Alloc = std::allocator<T>;
49
50 struct Base { };
51 struct Derived : Base { };
52
53 // Positive cases:
54
55 static_assert( can_reset<const void, void*>(),
56 "void* convertible to const void*");
57 static_assert( can_reset<const int, int*>(),
58 "int* convertible to const int*");
59 static_assert( can_reset<Base, Derived*>(),
60 "Derived* convertible to Base*");
61 static_assert( can_reset<const Base, Derived*>(),
62 "Derived* convertible to const Base*");
63
64 // Negative cases:
65
66 static_assert( !can_reset<int, void*>(),
67 "void* not convertible to int*");
68 static_assert( !can_reset<int, void*, Deleter<int>>(),
69 "void* not convertible to int*");
70 static_assert( !can_reset<int, void*, Deleter<int>, Alloc<int>>(),
71 "void* not convertible to int*");
72
73 static_assert( !can_reset<int, const int*>(),
74 "const int* not convertible to int*");
75 static_assert( !can_reset<int, const int*, Deleter<int>>(),
76 "const int* not convertible to int*");
77 static_assert( !can_reset<int, const int*, Deleter<int>, Alloc<int>>(),
78 "const int* not convertible to int*");
79
80 static_assert( !can_reset<int, long*>(),
81 "long* not convertible to int*");
82 static_assert( !can_reset<int, long*, Deleter<int>>(),
83 "long* not convertible to int*");
84 static_assert( !can_reset<int, long*, Deleter<int>, Alloc<int>>(),
85 "long* not convertible to int*");
86
87 static_assert( !can_reset<Derived, Base*>(),
88 "Base* not convertible to Derived*");
89 static_assert( !can_reset<Derived, Base*, Deleter<int>>(),
90 "Base* not convertible to Derived*");
91 static_assert( !can_reset<Derived, Base*, Deleter<int>, Alloc<int>>(),
92 "Base* not convertible to Derived*");
93