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
|
// { dg-options "-std=gnu++17" }
// Copyright (C) 2016-2018 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
#include <variant>
#include <testsuite_hooks.h>
class S{}; // No hash specialization
template<class T>
auto f(int) -> decltype(std::hash<std::variant<T>>(), std::true_type());
template<class T>
auto f(...) -> decltype(std::false_type());
static_assert(!decltype(f<S>(0))::value, "");
static_assert(!decltype(f<std::variant<S>>(0))::value, "");
static_assert(!decltype(f<std::variant<S, S>>(0))::value, "");
static_assert(decltype(f<std::variant<int>>(0))::value, "");
static_assert(decltype(f<std::variant<int, int>>(0))::value, "");
static_assert(!std::is_invocable_v<
std::hash<std::variant<S>>&, std::variant<S> const&> );
static_assert(!std::is_invocable_v<
std::hash<std::variant<S, int>>&, std::variant<S, int> const&> );
static_assert(std::is_invocable_v<
std::hash<std::variant<int>>&, std::variant<int> const&> );
static_assert(std::is_invocable_v<
std::hash<std::variant<int, int>>&, std::variant<int, int> const&> );
int main()
{
int x = 42;
std::variant<int> x2 = 42;
VERIFY(std::hash<int>()(x) == std::hash<std::variant<int>>()(x2));
}
|
