51 lines
1.8 KiB
C++
51 lines
1.8 KiB
C++
// { dg-options "-std=gnu++17" }
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// Copyright (C) 2016-2019 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING3. If not see
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// <http://www.gnu.org/licenses/>.
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#include <variant>
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#include <testsuite_hooks.h>
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class S{}; // No hash specialization
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template<class T>
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auto f(int) -> decltype(std::hash<std::variant<T>>(), std::true_type());
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template<class T>
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auto f(...) -> decltype(std::false_type());
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static_assert(!decltype(f<S>(0))::value, "");
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static_assert(!decltype(f<std::variant<S>>(0))::value, "");
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static_assert(!decltype(f<std::variant<S, S>>(0))::value, "");
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static_assert(decltype(f<std::variant<int>>(0))::value, "");
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static_assert(decltype(f<std::variant<int, int>>(0))::value, "");
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static_assert(!std::is_invocable_v<
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std::hash<std::variant<S>>&, std::variant<S> const&> );
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static_assert(!std::is_invocable_v<
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std::hash<std::variant<S, int>>&, std::variant<S, int> const&> );
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static_assert(std::is_invocable_v<
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std::hash<std::variant<int>>&, std::variant<int> const&> );
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static_assert(std::is_invocable_v<
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std::hash<std::variant<int, int>>&, std::variant<int, int> const&> );
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int main()
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{
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int x = 42;
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std::variant<int> x2 = 42;
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VERIFY(std::hash<int>()(x) == std::hash<std::variant<int>>()(x2));
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}
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