62 lines
1.9 KiB
C++
62 lines
1.9 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++03, c++11, c++14, c++17
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// UNSUPPORTED: libcpp-no-concepts
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// template<class F, class... Args>
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// concept equivalence_relation;
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#include <concepts>
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// clang-format off
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template<class F, class T, class U>
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requires std::relation<F, T, U>
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constexpr bool check_subsumption() { return false; }
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template<class F, class T>
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requires std::equivalence_relation<F, T, T> && true
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constexpr bool check_subsumption() { return false; }
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template<class F, class T, class U>
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requires std::equivalence_relation<F, T, U> && true
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constexpr bool check_subsumption() { return true; }
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// clang-format on
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static_assert(check_subsumption<int (*)(int, int), int, int>());
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static_assert(check_subsumption<int (*)(int, double), int, double>());
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struct S1 {};
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struct S2 {};
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struct R {
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bool operator()(S1, S1) const;
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bool operator()(S1, S2) const;
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bool operator()(S2, S1) const;
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bool operator()(S2, S2) const;
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};
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static_assert(check_subsumption<R, S1, S1>());
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static_assert(check_subsumption<R, S1, S2>());
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// clang-format off
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template<class F, class T, class U>
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requires std::relation<F, T, U> && true
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constexpr bool check_reverse_subsumption() { return true; }
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template<class F, class T, class U>
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requires std::equivalence_relation<F, T, U>
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constexpr bool check_no_subsumption() { return false; }
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// clang-format on
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static_assert(check_reverse_subsumption<int (*)(int, int), int, int>());
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static_assert(check_reverse_subsumption<int (*)(int, double), int, double>());
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static_assert(check_reverse_subsumption<R, S1, S1>());
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static_assert(check_reverse_subsumption<R, S1, S2>());
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int main(int, char**) { return 0; }
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