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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++03, c++11, c++14, c++17
// template<class F, class... Args>
// concept relation;
#include <concepts>
struct S1 {};
struct S2 {};
struct R {
bool operator()(S1, S1) const;
bool operator()(S1, S2) const;
bool operator()(S2, S1) const;
bool operator()(S2, S2) const;
};
// clang-format off
template<class F, class T, class U>
requires std::predicate<F, T, T> && std::predicate<F, T, U> &&
std::predicate<F, U, T> && std::predicate<F, U, U>
constexpr bool check_relation_subsumes_predicate() {
return false;
}
template<class F, class T, class U>
requires std::relation<F, T, U> && true
constexpr bool check_relation_subsumes_predicate() {
return true;
}
// clang-format on
static_assert(
check_relation_subsumes_predicate<int (*)(int, double), int, int>());
static_assert(
check_relation_subsumes_predicate<int (*)(int, double), int, double>());
static_assert(check_relation_subsumes_predicate<R, S1, S1>());
static_assert(check_relation_subsumes_predicate<R, S1, S2>());
// clang-format off
template<class F, class T, class U>
requires std::relation<F, T, T> && std::relation<F, U, U>
constexpr bool check_relation_subsumes_itself() {
return false;
}
template<class F, class T, class U>
requires std::relation<F, T, U>
constexpr bool check_relation_subsumes_itself() {
return true;
}
// clang-format on
static_assert(check_relation_subsumes_itself<int (*)(int, double), int, int>());
static_assert(check_relation_subsumes_itself<R, S1, S1>());
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