141 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// <utility>10 11// template <class T1, class T2> struct pair12 13// template <class T1, class T2, class U1, class U2>14// constexpr common_comparison_category_t<synth-three-way-result<T1, U1>,synth-three-way-result<T2, U2>>15// operator<=>(const pair<T1,T2>&, const pair<U1,U2>&);16 17// UNSUPPORTED: c++03, c++11, c++14, c++1718 19#include <cassert>20#include <compare>21#include <limits>22#include <type_traits> // std::is_constant_evaluated23#include <utility>24#include <string>25 26#include "test_macros.h"27 28template <class T>29concept HasEqual = requires(T t) { t == t; };30template <class T>31concept HasLess = requires(T t) { t < t; };32template <class T, class U = T>33concept HasSpaceship = requires(T t, U u) { t <=> u; };34 35constexpr bool test() {36 {37 // Pairs of different types should compare with strong ordering.38 using P1 = std::pair<int, int>;39 using P2 = std::pair<long long, long long>;40 ASSERT_SAME_TYPE(decltype(P1() <=> P2()), std::strong_ordering);41 assert((P1(1, 1) <=> P2(1, 2)) == std::strong_ordering::less);42 assert((P1(2, 1) <=> P2(1, 2)) == std::strong_ordering::greater);43 assert((P1(0, 0) <=> P2(0, 0)) == std::strong_ordering::equal);44 }45 {46 // Pairs of different types should compare with partial ordering.47 using P1 = std::pair<int, int>;48 using P2 = std::pair<double, double>;49 ASSERT_SAME_TYPE(decltype(P1() <=> P2()), std::partial_ordering);50 assert((P1(1, 1) <=> P2(1.0, 2.0)) == std::partial_ordering::less);51 assert((P1(2, 1) <=> P2(1.0, 2.0)) == std::partial_ordering::greater);52 assert((P1(0, 0) <=> P2(0.0, 0.0)) == std::partial_ordering::equivalent);53 }54 { static_assert(!HasSpaceship<std::pair<int, int>, std::pair<std::string, int>>); }55 {56 // Pairs of types that both have strong ordering should compare with strong ordering.57 using P = std::pair<int, int>;58 ASSERT_SAME_TYPE(decltype(P() <=> P()), std::strong_ordering);59 assert((P(1, 1) <=> P(1, 2)) == std::strong_ordering::less);60 assert((P(2, 1) <=> P(1, 2)) == std::strong_ordering::greater);61 assert((P(0, 0) <=> P(0, 0)) == std::strong_ordering::equal);62 }63 {64 // Pairs of int and a type with no spaceship operator should compare with weak ordering.65 struct NoSpaceship {66 int value;67 constexpr bool operator==(const NoSpaceship&) const = default;68 constexpr bool operator<(const NoSpaceship& other) const { return value < other.value; }69 };70 using P = std::pair<int, NoSpaceship>;71 ASSERT_SAME_TYPE(decltype(P() <=> P()), std::weak_ordering);72 assert((P(1, {1}) <=> P(1, {2})) == std::weak_ordering::less);73 assert((P(2, {1}) <=> P(1, {2})) == std::weak_ordering::greater);74 assert((P(0, {0}) <=> P(0, {0})) == std::weak_ordering::equivalent);75 }76 {77 // Pairs of int (strongly ordered) and double (partially ordered) should compare with partial ordering.78 using P = std::pair<int, double>;79 constexpr double nan = std::numeric_limits<double>::quiet_NaN();80 ASSERT_SAME_TYPE(decltype(P() <=> P()), std::partial_ordering);81 assert((P(1, 1.0) <=> P(1, 2.0)) == std::partial_ordering::less);82 assert((P(1, 1.0) <=> P(1, 1.0)) == std::partial_ordering::equivalent);83 assert((P(1, -0.0) <=> P(1, 0.0)) == std::partial_ordering::equivalent);84 assert((P(1, 2.0) <=> P(1, 1.0)) == std::partial_ordering::greater);85 assert((P(1, nan) <=> P(2, nan)) == std::partial_ordering::less);86 assert((P(2, nan) <=> P(1, nan)) == std::partial_ordering::greater);87 assert((P(1, nan) <=> P(1, nan)) == std::partial_ordering::unordered);88 }89 {90 using P = std::pair<double, int>;91 constexpr double nan = std::numeric_limits<double>::quiet_NaN();92 ASSERT_SAME_TYPE(decltype(P() <=> P()), std::partial_ordering);93 assert((P(2.0, 1) <=> P(1.0, 2)) == std::partial_ordering::greater);94 assert((P(1.0, 1) <=> P(1.0, 2)) == std::partial_ordering::less);95 assert((P(nan, 1) <=> P(nan, 2)) == std::partial_ordering::unordered);96 }97 {98 struct NoRelative {99 constexpr bool operator==(const NoRelative&) const;100 };101 static_assert(HasEqual<std::pair<int, NoRelative>>);102 static_assert(!HasLess<std::pair<int, NoRelative>>);103 static_assert(!HasSpaceship<std::pair<int, NoRelative>>);104 }105 {106 struct NoLessThan {107 constexpr bool operator==(const NoLessThan&) const;108 constexpr bool operator>(const NoLessThan&) const;109 };110 static_assert(HasEqual<std::pair<int, NoLessThan>>);111 static_assert(!HasLess<std::pair<int, NoLessThan>>);112 static_assert(!HasSpaceship<std::pair<int, NoLessThan>>);113 }114 115#ifdef TEST_COMPILER_GCC116 // GCC cannot evaluate NaN @ non-NaN constexpr, so test that runtime-only.117 if (!std::is_constant_evaluated())118#endif119 {120 {121 using P = std::pair<int, double>;122 constexpr double nan = std::numeric_limits<double>::quiet_NaN();123 assert((P(1, 2.0) <=> P(1, nan)) == std::partial_ordering::unordered);124 }125 {126 using P = std::pair<double, int>;127 constexpr double nan = std::numeric_limits<double>::quiet_NaN();128 assert((P(1.0, 1) <=> P(nan, 2)) == std::partial_ordering::unordered);129 }130 }131 132 return true;133}134 135int main(int, char**) {136 test();137 static_assert(test());138 139 return 0;140}141