P1614R2 Spaceship: Clause 27: Time (partial, pre-C++20 types) (#1602)

Co-authored-by: Stephan T. Lavavej <[email protected]>

stl/inc/chrono

@@ -17,6 +17,9 @@
 
 #if _HAS_CXX20
 #include <compare>
+#ifdef __cpp_lib_concepts
+#include <concepts>
+#endif // defined(__cpp_lib_concepts)
 #endif // _HAS_CXX20
 
 #pragma pack(push, _CRT_PACKING)
@@ -370,12 +373,14 @@ namespace chrono {
         return _CT(_Left).count() == _CT(_Right).count();
     }
 
+#if !_HAS_CXX20
     template <class _Rep1, class _Period1, class _Rep2, class _Period2>
     _NODISCARD constexpr bool
         operator!=(const duration<_Rep1, _Period1>& _Left, const duration<_Rep2, _Period2>& _Right) noexcept(
             is_arithmetic_v<_Rep1>&& is_arithmetic_v<_Rep2>) /* strengthened */ {
         return !(_Left == _Right);
     }
+#endif // !_HAS_CXX20
 
     template <class _Rep1, class _Period1, class _Rep2, class _Period2>
     _NODISCARD constexpr bool
@@ -406,6 +411,19 @@ namespace chrono {
         return !(_Left < _Right);
     }
 
+#ifdef __cpp_lib_concepts
+    // clang-format off
+    template <class _Rep1, class _Period1, class _Rep2, class _Period2>
+        requires three_way_comparable<typename common_type_t<duration<_Rep1, _Period1>, duration<_Rep2, _Period2>>::rep>
+    _NODISCARD constexpr auto
+        operator<=>(const duration<_Rep1, _Period1>& _Left, const duration<_Rep2, _Period2>& _Right) noexcept(
+            is_arithmetic_v<_Rep1>&& is_arithmetic_v<_Rep2>) /* strengthened */ {
+        // clang-format on
+        using _CT = common_type_t<duration<_Rep1, _Period1>, duration<_Rep2, _Period2>>;
+        return _CT(_Left).count() <=> _CT(_Right).count();
+    }
+#endif // defined(__cpp_lib_concepts)
+
     // FUNCTION TEMPLATE duration_cast
     template <class _To, class _Rep, class _Period, enable_if_t<_Is_duration_v<_To>, int> _Enabled>
     _NODISCARD constexpr _To duration_cast(const duration<_Rep, _Period>& _Dur) noexcept(
@@ -550,12 +568,14 @@ namespace chrono {
         return _Left.time_since_epoch() == _Right.time_since_epoch();
     }
 
+#if !_HAS_CXX20
     template <class _Clock, class _Duration1, class _Duration2>
     _NODISCARD constexpr bool
         operator!=(const time_point<_Clock, _Duration1>& _Left, const time_point<_Clock, _Duration2>& _Right) noexcept(
             is_arithmetic_v<typename _Duration1::rep>&& is_arithmetic_v<typename _Duration2::rep>) /* strengthened */ {
         return !(_Left == _Right);
     }
+#endif // !_HAS_CXX20
 
     template <class _Clock, class _Duration1, class _Duration2>
     _NODISCARD constexpr bool
@@ -585,6 +605,15 @@ namespace chrono {
         return !(_Left < _Right);
     }
 
+#ifdef __cpp_lib_concepts
+    template <class _Clock, class _Duration1, three_way_comparable_with<_Duration1> _Duration2>
+    _NODISCARD constexpr auto
+        operator<=>(const time_point<_Clock, _Duration1>& _Left, const time_point<_Clock, _Duration2>& _Right) noexcept(
+            is_arithmetic_v<typename _Duration1::rep>&& is_arithmetic_v<typename _Duration2::rep>) /* strengthened */ {
+        return _Left.time_since_epoch() <=> _Right.time_since_epoch();
+    }
+#endif // defined(__cpp_lib_concepts)
+
     // FUNCTION TEMPLATE time_point_cast
     template <class _To, class _Clock, class _Duration, enable_if_t<_Is_duration_v<_To>, int> = 0>
     _NODISCARD constexpr time_point<_Clock, _To> time_point_cast(const time_point<_Clock, _Duration>& _Time) noexcept(

tests/std/test.lst

@@ -398,6 +398,7 @@ tests\P1135R6_semaphore
 tests\P1165R1_consistently_propagating_stateful_allocators
 tests\P1423R3_char8_t_remediation
 tests\P1502R1_standard_library_header_units
+tests\P1614R2_spaceship
 tests\P1645R1_constexpr_numeric
 tests\VSO_0000000_allocator_propagation
 tests\VSO_0000000_any_calling_conventions

tests/std/tests/P1614R2_spaceship/env.lst

@@ -0,0 +1,7 @@
+# Copyright (c) Microsoft Corporation.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+RUNALL_INCLUDE ..\concepts_matrix.lst
+RUNALL_CROSSLIST
+PM_CL="/D_STL_OPTIMIZE_SYSTEM_ERROR_OPERATORS=0"
+PM_CL="/D_STL_OPTIMIZE_SYSTEM_ERROR_OPERATORS=1"

tests/std/tests/P1614R2_spaceship/test.cpp

@@ -0,0 +1,262 @@
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// Covers:
+// * spaceship for containers
+
+#include <array>
+#include <cassert>
+#include <chrono>
+#include <compare>
+#include <concepts>
+#include <deque>
+#include <filesystem>
+#include <forward_list>
+#include <functional>
+#include <iostream>
+#include <limits>
+#include <list>
+#include <map>
+#include <queue>
+#include <ranges>
+#include <ratio>
+#include <regex>
+#include <set>
+#include <stack>
+#include <string>
+#include <system_error>
+#include <thread>
+#include <type_traits>
+#include <unordered_map>
+#include <unordered_set>
+#include <utility>
+#include <vector>
+
+template <class T>
+using SpaceshipType = decltype(std::declval<T>() <=> std::declval<T>());
+
+template <class T, class U>
+concept HasSpaceshipWith = requires {
+    std::declval<T>() <=> std::declval<U>();
+};
+
+using PartiallyOrdered = double;
+
+struct WeaklyOrdered {
+    [[nodiscard]] constexpr bool operator==(const WeaklyOrdered&) const {
+        return true;
+    }
+
+    [[nodiscard]] constexpr std::weak_ordering operator<=>(const WeaklyOrdered&) const {
+        return std::weak_ordering::equivalent;
+    }
+};
+
+using StronglyOrdered = int;
+
+// Activates synth-three-way in N4861 16.4.2.1 [expos.only.func]/2.
+struct SynthOrdered {
+    int val;
+
+    constexpr SynthOrdered(const int x) : val{x} {}
+
+    [[nodiscard]] constexpr bool operator==(const SynthOrdered& other) const {
+        return val == other.val;
+    }
+
+    [[nodiscard]] constexpr bool operator<(const SynthOrdered& other) const {
+        return val < other.val;
+    }
+};
+
+struct OrderedChar {
+    OrderedChar() = default;
+    OrderedChar(const char other) : c(other) {}
+
+    OrderedChar& operator=(const char& other) {
+        c = other;
+        return *this;
+    }
+
+    auto operator<=>(const OrderedChar&) const = default;
+
+    operator char() const {
+        return c;
+    }
+
+    char c;
+};
+
+struct WeaklyOrderedChar : OrderedChar {};
+struct WeaklyOrderedByOmissionChar : OrderedChar {};
+struct PartiallyOrderedChar : OrderedChar {};
+
+namespace std {
+    template <>
+    struct char_traits<OrderedChar> : char_traits<char> {
+        using char_type = OrderedChar;
+
+        static int compare(const char_type* first1, const char_type* first2, size_t count) {
+            for (; 0 < count; --count, ++first1, ++first2) {
+                if (*first1 != *first2) {
+                    return *first1 < *first2 ? -1 : +1;
+                }
+            }
+
+            return 0;
+        }
+
+        static bool eq(const char_type l, const char_type r) {
+            return l.c == r.c;
+        }
+    };
+
+    template <>
+    struct char_traits<WeaklyOrderedChar> : char_traits<OrderedChar> {
+        using char_type           = WeaklyOrderedChar;
+        using comparison_category = weak_ordering;
+    };
+
+    template <>
+    struct char_traits<WeaklyOrderedByOmissionChar> : char_traits<OrderedChar> {
+        using char_type = WeaklyOrderedByOmissionChar;
+
+    private:
+        using comparison_category = strong_ordering;
+    };
+
+    template <>
+    struct char_traits<PartiallyOrderedChar> : char_traits<OrderedChar> {
+        using char_type           = PartiallyOrderedChar;
+        using comparison_category = partial_ordering;
+    };
+} // namespace std
+
+struct dummy_diagnostic : std::error_category {
+    const char* name() const noexcept override {
+        return "dummy";
+    }
+    std::string message(int) const override {
+        return "";
+    }
+};
+
+template <class ReturnType, class SmallType, class EqualType, class LargeType>
+void spaceship_test(const SmallType& smaller, const EqualType& smaller_equal, const LargeType& larger) {
+    assert(smaller == smaller_equal);
+    assert(smaller_equal == smaller);
+    assert(smaller != larger);
+    assert(larger != smaller);
+    assert(smaller < larger);
+    assert(!(larger < smaller));
+    assert(larger > smaller);
+    assert(!(smaller > larger));
+    assert(smaller <= larger);
+    assert(!(larger <= smaller));
+    assert(larger >= smaller);
+    assert(!(smaller >= larger));
+    assert((smaller <=> larger) < 0);
+    assert((larger <=> smaller) > 0);
+    assert((smaller <=> smaller_equal) == 0);
+
+    static_assert(std::is_same_v<decltype(smaller <=> larger), ReturnType>);
+}
+
+template <class T>
+inline constexpr bool is_pair = false;
+template <class A, class B>
+inline constexpr bool is_pair<std::pair<A, B>> = true; // TRANSITION, std::pair spaceship not yet implemented
+
+template <class Container>
+void ordered_containers_test(const Container& smaller, const Container& smaller_equal, const Container& larger) {
+    using Elem = typename Container::value_type;
+    if constexpr (is_pair<Elem> // TRANSITION, std::pair spaceship not yet implemented
+                  || std::is_same_v<Elem, SynthOrdered>) {
+        spaceship_test<std::weak_ordering>(smaller, smaller_equal, larger);
+    } else {
+        spaceship_test<std::strong_ordering>(smaller, smaller_equal, larger);
+    }
+}
+
+template <class Container>
+void unordered_containers_test(
+    const Container& something, const Container& something_equal, const Container& different) {
+    assert(something == something_equal);
+    assert(something != different);
+}
+
+template <class ErrorType>
+void diagnostics_test() {
+    dummy_diagnostic c_mem[2];
+    {
+        ErrorType e_smaller(0, c_mem[0]);
+        ErrorType e_equal(0, c_mem[0]);
+        ErrorType e_larger(1, c_mem[1]);
+
+        spaceship_test<std::strong_ordering>(e_smaller, e_equal, e_larger);
+    }
+    {
+        ErrorType e_smaller(0, c_mem[0]);
+        ErrorType e_larger(0, c_mem[1]);
+
+        assert(e_smaller < e_larger);
+        assert(!(e_larger < e_smaller));
+        assert((e_smaller <=> e_larger) < 0);
+        assert((e_larger <=> e_smaller) > 0);
+    }
+    {
+        ErrorType e_smaller(0, c_mem[0]);
+        ErrorType e_larger(1, c_mem[0]);
+
+        assert(e_smaller < e_larger);
+        assert(!(e_larger < e_smaller));
+        assert((e_smaller <=> e_larger) < 0);
+        assert((e_larger <=> e_smaller) > 0);
+    }
+}
+
+void ordering_test_cases() {
+    { // chrono::duration
+        using std::chrono::hours;
+        using std::chrono::minutes;
+        using std::chrono::seconds;
+
+        spaceship_test<std::strong_ordering>(seconds{1}, seconds{1}, seconds{2});
+        spaceship_test<std::strong_ordering>(seconds{3600}, hours{1}, minutes{61});
+
+        using double_seconds     = std::chrono::duration<double>;
+        using float_milliseconds = std::chrono::duration<float, std::milli>;
+        using ntsc_fields        = std::chrono::duration<long long, std::ratio<1001, 60000>>;
+
+        spaceship_test<std::partial_ordering>(double_seconds{1}, float_milliseconds{1000}, ntsc_fields{60});
+
+        constexpr double_seconds nan_s{std::numeric_limits<double>::quiet_NaN()};
+#ifdef __clang__ // TRANSITION, DevCom-445462
+        static_assert(nan_s <=> nan_s == std::partial_ordering::unordered);
+#endif // defined(__clang__)
+        assert(nan_s <=> nan_s == std::partial_ordering::unordered);
+    }
+    { // chrono::time_point
+        using std::chrono::milliseconds;
+        using double_seconds = std::chrono::duration<double>;
+        using sys_tp         = std::chrono::system_clock::time_point;
+        using sys_ms         = std::chrono::time_point<std::chrono::system_clock, milliseconds>;
+        using sys_double_s   = std::chrono::time_point<std::chrono::system_clock, double_seconds>;
+
+        spaceship_test<std::strong_ordering>(sys_tp{}, sys_ms{}, sys_ms{milliseconds{1}});
+        spaceship_test<std::partial_ordering>(sys_tp{}, sys_double_s{}, sys_double_s{double_seconds{1}});
+
+        constexpr sys_double_s nan_tp{double_seconds{std::numeric_limits<double>::quiet_NaN()}};
+#ifdef __clang__ // TRANSITION, DevCom-445462
+        static_assert(nan_tp <=> nan_tp == std::partial_ordering::unordered);
+#endif // defined(__clang__)
+        assert(nan_tp <=> nan_tp == std::partial_ordering::unordered);
+
+        using steady_tp = std::chrono::steady_clock::time_point;
+        static_assert(!HasSpaceshipWith<sys_tp, steady_tp>);
+    }
+}
+
+int main() {
+    ordering_test_cases();
+}