83 lines · cpp
1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9// UNSUPPORTED: c++03, c++11, c++14, c++1710 11// <compare>12// <functional>13 14// compare_three_way15 16#include <compare>17#include <cassert>18#include <limits>19#include <type_traits>20 21#include "pointer_comparison_test_helper.h"22 23template<class T, class U>24constexpr auto test_sfinae(T t, U u)25 -> decltype(std::compare_three_way()(t, u), std::true_type{})26 { return std::true_type{}; }27 28constexpr auto test_sfinae(...)29 { return std::false_type{}; }30 31struct NotThreeWayComparable {32 std::strong_ordering operator<=>(const NotThreeWayComparable&) const;33};34ASSERT_SAME_TYPE(std::compare_three_way_result_t<NotThreeWayComparable>, std::strong_ordering);35static_assert(!std::three_way_comparable<NotThreeWayComparable>); // it lacks operator==36 37struct WeaklyOrdered {38 int i;39 friend constexpr std::weak_ordering operator<=>(const WeaklyOrdered&, const WeaklyOrdered&) = default;40};41 42constexpr bool test()43{44 ASSERT_SAME_TYPE(decltype(std::compare_three_way()(1, 1)), std::strong_ordering);45 assert(std::compare_three_way()(1, 2) == std::strong_ordering::less);46 assert(std::compare_three_way()(1, 1) == std::strong_ordering::equal);47 assert(std::compare_three_way()(2, 1) == std::strong_ordering::greater);48 49 ASSERT_SAME_TYPE(decltype(std::compare_three_way()(WeaklyOrdered{1}, WeaklyOrdered{2})), std::weak_ordering);50 assert(std::compare_three_way()(WeaklyOrdered{1}, WeaklyOrdered{2}) == std::weak_ordering::less);51 assert(std::compare_three_way()(WeaklyOrdered{1}, WeaklyOrdered{1}) == std::weak_ordering::equivalent);52 assert(std::compare_three_way()(WeaklyOrdered{2}, WeaklyOrdered{1}) == std::weak_ordering::greater);53 54 ASSERT_SAME_TYPE(decltype(std::compare_three_way()(1.0, 1.0)), std::partial_ordering);55 double nan = std::numeric_limits<double>::quiet_NaN();56 assert(std::compare_three_way()(1.0, 2.0) == std::partial_ordering::less);57 assert(std::compare_three_way()(1.0, 1.0) == std::partial_ordering::equivalent);58 assert(std::compare_three_way()(2.0, 1.0) == std::partial_ordering::greater);59 assert(std::compare_three_way()(nan, nan) == std::partial_ordering::unordered);60 61 // Try heterogeneous comparison.62 ASSERT_SAME_TYPE(decltype(std::compare_three_way()(42.0, 42)), std::partial_ordering);63 assert(std::compare_three_way()(42.0, 42) == std::partial_ordering::equivalent);64 ASSERT_SAME_TYPE(decltype(std::compare_three_way()(42, 42.0)), std::partial_ordering);65 assert(std::compare_three_way()(42, 42.0) == std::partial_ordering::equivalent);66 67 return true;68}69 70int main(int, char**)71{72 test();73 static_assert(test());74 75 do_pointer_comparison_test(std::compare_three_way());76 77 static_assert(test_sfinae(1, 2));78 static_assert(!test_sfinae(1, nullptr));79 static_assert(!test_sfinae(NotThreeWayComparable(), NotThreeWayComparable()));80 81 return 0;82}83