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Merged
merged 12 commits into from
Jul 20, 2020
Merged

Remove obsolete conditional compilation from <compare> #1049

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eddf626
Remove obsolete conditional compilation from <compare>
CaseyCarter Jul 16, 2020
381d91b
Break <compare> ABI again, and fix #1050
CaseyCarter Jul 16, 2020
0803efa
Review comments
CaseyCarter Jul 17, 2020
6a1e8d9
Audit for all occurrences of __cpp_impl_three_way_comparison
CaseyCarter Jul 17, 2020
7dffee7
Test 0 < MEOW
CaseyCarter Jul 17, 2020
3b2ec70
Statementreply's review comments; eliminate redundant coverage
CaseyCarter Jul 17, 2020
89b380b
Review comments
CaseyCarter Jul 17, 2020
0209d3e
Workaround DevCom-1117991 and document partial_ordering::operator<=
CaseyCarter Jul 18, 2020
b6013a9
Document partial_ordering::operator<=> as well
CaseyCarter Jul 18, 2020
262caaa
Fix math (0x80 - 1 == 0x7f), Oxford commas, iff, rewrap.
StephanTLavavej Jul 18, 2020
9c67ea7
Merge branch 'master' into compare
StephanTLavavej Jul 18, 2020
9bb982c
Simplify compiler bug workaround
StephanTLavavej Jul 18, 2020
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104 changes: 32 additions & 72 deletions stl/inc/compare
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Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,7 @@ using _Compare_t = signed char;
// These "pretty" enumerator names are safe since they reuse names of user-facing entities.
enum class _Compare_eq : _Compare_t { equal = 0, equivalent = equal };
enum class _Compare_ord : _Compare_t { less = -1, greater = 1 };
enum class _Compare_ncmp : _Compare_t { unordered = -127 };
enum class _Compare_ncmp : _Compare_t { unordered = -128 };

// CLASS partial_ordering
class partial_ordering {
Expand All @@ -53,21 +53,7 @@ public:
return _Val._Value == 0;
}

#if defined(__cpp_impl_three_way_comparison) && __cpp_impl_three_way_comparison >= 201902L
_NODISCARD friend constexpr bool operator==(const partial_ordering&, const partial_ordering&) noexcept = default;
#else // ^^^ supports <=> and P1185 / supports neither vvv
_NODISCARD friend constexpr bool operator!=(const partial_ordering _Val, _Literal_zero) noexcept {
return _Val._Value != 0;
}

_NODISCARD friend constexpr bool operator==(_Literal_zero, const partial_ordering _Val) noexcept {
return 0 == _Val._Value;
}

_NODISCARD friend constexpr bool operator!=(_Literal_zero, const partial_ordering _Val) noexcept {
return 0 != _Val._Value;
}
#endif // defined(__cpp_impl_three_way_comparison) && __cpp_impl_three_way_comparison >= 201902L
_NODISCARD friend constexpr bool operator==(partial_ordering, partial_ordering) noexcept = default;

_NODISCARD friend constexpr bool operator<(const partial_ordering _Val, _Literal_zero) noexcept {
return _Val._Value == static_cast<_Compare_t>(_Compare_ord::less);
Expand All @@ -78,44 +64,50 @@ public:
}

_NODISCARD friend constexpr bool operator<=(const partial_ordering _Val, _Literal_zero) noexcept {
return _Val._Value <= 0 && _Val._Is_ordered();
// The stored value is either less (0xff), equivalent (0x00), greater (0x01), or unordered (0x80).
// Subtracting 1 produces either 0xfe, 0xff, 0x00, or 0x7f. The high bit is set in the result
// if and only if the initial value was less or equivalent, for which we want to return true.
#if defined(__clang__) || defined(__EDG__) // TRANSITION, DevCom-1117991
return static_cast<signed char>(static_cast<unsigned char>(_Val._Value) - 1) < 0;
#else // ^^^ no workaround / workaround vvv
auto _Tmp = static_cast<unsigned char>(_Val._Value);
--_Tmp;
return static_cast<bool>(_Tmp >> 7);
#endif // TRANSITION, DevCom-1117991
}

_NODISCARD friend constexpr bool operator>=(const partial_ordering _Val, _Literal_zero) noexcept {
return _Val._Value >= 0;
}

_NODISCARD friend constexpr bool operator<(_Literal_zero, const partial_ordering _Val) noexcept {
return 0 < _Val._Value;
return _Val > 0;
}

_NODISCARD friend constexpr bool operator>(_Literal_zero, const partial_ordering _Val) noexcept {
return 0 > _Val._Value && _Val._Is_ordered();
return _Val < 0;
}

_NODISCARD friend constexpr bool operator<=(_Literal_zero, const partial_ordering _Val) noexcept {
return 0 <= _Val._Value;
return _Val >= 0;
}

_NODISCARD friend constexpr bool operator>=(_Literal_zero, const partial_ordering _Val) noexcept {
return 0 >= _Val._Value && _Val._Is_ordered();
return _Val <= 0;
}

#ifdef __cpp_impl_three_way_comparison
_NODISCARD friend constexpr partial_ordering operator<=>(const partial_ordering _Val, _Literal_zero) noexcept {
return _Val;
}

_NODISCARD friend constexpr partial_ordering operator<=>(_Literal_zero, const partial_ordering _Val) noexcept {
return partial_ordering{static_cast<_Compare_ord>(-_Val._Value)};
// The stored value is either less (0xff), equivalent (0x00), greater (0x01), or unordered (0x80).
// Subtracting from 0 produces either 0x01, 0x00, 0xff, or 0x80. Note that the effect is to
// exchange less for greater (and vice versa), while leaving equivalent and unordered unchanged.
return partial_ordering{static_cast<_Compare_ord>(0 - static_cast<unsigned int>(_Val._Value))};
}
#endif // __cpp_impl_three_way_comparison

private:
_NODISCARD constexpr bool _Is_ordered() const noexcept {
return _Value != static_cast<_Compare_t>(_Compare_ncmp::unordered);
}

_Compare_t _Value;
};

Expand Down Expand Up @@ -144,21 +136,7 @@ public:
return _Val._Value == 0;
}

#if defined(__cpp_impl_three_way_comparison) && __cpp_impl_three_way_comparison >= 201902L
_NODISCARD friend constexpr bool operator==(const weak_ordering&, const weak_ordering&) noexcept = default;
#else // ^^^ supports <=> and P1185 / supports neither vvv
_NODISCARD friend constexpr bool operator!=(const weak_ordering _Val, _Literal_zero) noexcept {
return _Val._Value != 0;
}

_NODISCARD friend constexpr bool operator==(_Literal_zero, const weak_ordering _Val) noexcept {
return 0 == _Val._Value;
}

_NODISCARD friend constexpr bool operator!=(_Literal_zero, const weak_ordering _Val) noexcept {
return 0 != _Val._Value;
}
#endif // defined(__cpp_impl_three_way_comparison) && __cpp_impl_three_way_comparison >= 201902L
_NODISCARD friend constexpr bool operator==(weak_ordering, weak_ordering) noexcept = default;

_NODISCARD friend constexpr bool operator<(const weak_ordering _Val, _Literal_zero) noexcept {
return _Val._Value < 0;
Expand All @@ -177,30 +155,28 @@ public:
}

_NODISCARD friend constexpr bool operator<(_Literal_zero, const weak_ordering _Val) noexcept {
return 0 < _Val._Value;
return _Val > 0;
}

_NODISCARD friend constexpr bool operator>(_Literal_zero, const weak_ordering _Val) noexcept {
return 0 > _Val._Value;
return _Val < 0;
}

_NODISCARD friend constexpr bool operator<=(_Literal_zero, const weak_ordering _Val) noexcept {
return 0 <= _Val._Value;
return _Val >= 0;
}

_NODISCARD friend constexpr bool operator>=(_Literal_zero, const weak_ordering _Val) noexcept {
return 0 >= _Val._Value;
return _Val <= 0;
}

#ifdef __cpp_impl_three_way_comparison
_NODISCARD friend constexpr weak_ordering operator<=>(const weak_ordering _Val, _Literal_zero) noexcept {
return _Val;
}

_NODISCARD friend constexpr weak_ordering operator<=>(_Literal_zero, const weak_ordering _Val) noexcept {
return weak_ordering{static_cast<_Compare_ord>(-_Val._Value)};
}
#endif // __cpp_impl_three_way_comparison

private:
_Compare_t _Value;
Expand Down Expand Up @@ -235,21 +211,7 @@ public:
return _Val._Value == 0;
}

#if defined(__cpp_impl_three_way_comparison) && __cpp_impl_three_way_comparison >= 201902L
_NODISCARD friend constexpr bool operator==(const strong_ordering&, const strong_ordering&) noexcept = default;
#else // ^^^ supports <=> and P1185 / supports neither vvv
_NODISCARD friend constexpr bool operator!=(const strong_ordering _Val, _Literal_zero) noexcept {
return _Val._Value != 0;
}

_NODISCARD friend constexpr bool operator==(_Literal_zero, const strong_ordering _Val) noexcept {
return 0 == _Val._Value;
}

_NODISCARD friend constexpr bool operator!=(_Literal_zero, const strong_ordering _Val) noexcept {
return 0 != _Val._Value;
}
#endif // defined(__cpp_impl_three_way_comparison) && __cpp_impl_three_way_comparison >= 201902L
_NODISCARD friend constexpr bool operator==(strong_ordering, strong_ordering) noexcept = default;

_NODISCARD friend constexpr bool operator<(const strong_ordering _Val, _Literal_zero) noexcept {
return _Val._Value < 0;
Expand All @@ -268,30 +230,28 @@ public:
}

_NODISCARD friend constexpr bool operator<(_Literal_zero, const strong_ordering _Val) noexcept {
return 0 < _Val._Value;
return _Val > 0;
}

_NODISCARD friend constexpr bool operator>(_Literal_zero, const strong_ordering _Val) noexcept {
return 0 > _Val._Value;
return _Val < 0;
}

_NODISCARD friend constexpr bool operator<=(_Literal_zero, const strong_ordering _Val) noexcept {
return 0 <= _Val._Value;
return _Val >= 0;
}

_NODISCARD friend constexpr bool operator>=(_Literal_zero, const strong_ordering _Val) noexcept {
return 0 >= _Val._Value;
return _Val <= 0;
}

#ifdef __cpp_impl_three_way_comparison
_NODISCARD friend constexpr strong_ordering operator<=>(const strong_ordering _Val, _Literal_zero) noexcept {
return _Val;
}

_NODISCARD friend constexpr strong_ordering operator<=>(_Literal_zero, const strong_ordering _Val) noexcept {
return strong_ordering{static_cast<_Compare_ord>(-_Val._Value)};
}
#endif // __cpp_impl_three_way_comparison

private:
_Compare_t _Value;
Expand Down Expand Up @@ -364,7 +324,7 @@ struct common_comparison_category {
using type = common_comparison_category_t<_Types...>;
};

#if defined(__cpp_impl_three_way_comparison) && defined(__cpp_lib_concepts)
#ifdef __cpp_lib_concepts
// clang-format off
template <class _Ty, class _Cat>
concept _Compares_as = same_as<common_comparison_category_t<_Ty, _Cat>, _Cat>;
Expand Down Expand Up @@ -409,7 +369,7 @@ struct compare_three_way {
using is_transparent = int;
};
// clang-format on
#endif // defined(__cpp_impl_three_way_comparison) && defined(__cpp_lib_concepts)
#endif // __cpp_lib_concepts

// Other components not yet implemented
_STD_END
Expand Down
30 changes: 1 addition & 29 deletions stl/inc/span
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Original file line number Diff line number Diff line change
Expand Up @@ -12,13 +12,11 @@
#if !_HAS_CXX20
#pragma message("The contents of <span> are available only with C++20 or later.")
#else // ^^^ !_HAS_CXX20 / _HAS_CXX20 vvv
#include <compare>
#include <cstddef>
#include <type_traits>
#include <xutility>

#if defined(__cpp_impl_three_way_comparison) && __cpp_impl_three_way_comparison >= 201902L
#include <compare>
#endif // defined(__cpp_impl_three_way_comparison) && __cpp_impl_three_way_comparison >= 201902L

#pragma pack(push, _CRT_PACKING)
#pragma warning(push, _STL_WARNING_LEVEL)
Expand Down Expand Up @@ -153,39 +151,13 @@ struct _Span_iterator {
return _Myptr == _Right._Myptr;
}

#if defined(__cpp_impl_three_way_comparison) && __cpp_impl_three_way_comparison >= 201902L
_NODISCARD constexpr strong_ordering operator<=>(const _Span_iterator& _Right) const noexcept {
#if _ITERATOR_DEBUG_LEVEL >= 1
_STL_VERIFY(
_Mybegin == _Right._Mybegin && _Myend == _Right._Myend, "cannot compare incompatible span iterators");
#endif // _ITERATOR_DEBUG_LEVEL >= 1
return _Myptr <=> _Right._Myptr;
}
#else // ^^^ use spaceship / no spaceship vvv
_NODISCARD constexpr bool operator!=(const _Span_iterator& _Right) const noexcept {
return !(*this == _Right);
}

_NODISCARD constexpr bool operator<(const _Span_iterator& _Right) const noexcept {
#if _ITERATOR_DEBUG_LEVEL >= 1
_STL_VERIFY(
_Mybegin == _Right._Mybegin && _Myend == _Right._Myend, "cannot compare incompatible span iterators");
#endif // _ITERATOR_DEBUG_LEVEL >= 1
return _Myptr < _Right._Myptr;
}

_NODISCARD constexpr bool operator>(const _Span_iterator& _Right) const noexcept {
return _Right < *this;
}

_NODISCARD constexpr bool operator<=(const _Span_iterator& _Right) const noexcept {
return !(_Right < *this);
}

_NODISCARD constexpr bool operator>=(const _Span_iterator& _Right) const noexcept {
return !(*this < _Right);
}
#endif // defined(__cpp_impl_three_way_comparison) && __cpp_impl_three_way_comparison >= 201902L

#if _ITERATOR_DEBUG_LEVEL >= 1
friend constexpr void _Verify_range(const _Span_iterator& _First, const _Span_iterator& _Last) noexcept {
Expand Down
31 changes: 8 additions & 23 deletions stl/inc/xutility
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Original file line number Diff line number Diff line change
Expand Up @@ -2105,13 +2105,13 @@ _NODISCARD _CONSTEXPR17 bool operator>=(const reverse_iterator<_BidIt1>& _Left,
#endif // __cpp_lib_concepts
{ return _Left._Get_current() <= _Right._Get_current(); }

#if defined(__cpp_impl_three_way_comparison) && defined(__cpp_lib_concepts)
#ifdef __cpp_lib_concepts
template <class _BidIt1, three_way_comparable_with<_BidIt1> _BidIt2>
_NODISCARD constexpr compare_three_way_result_t<_BidIt1, _BidIt2> operator<=>(
const reverse_iterator<_BidIt1>& _Left, const reverse_iterator<_BidIt2>& _Right) {
return _Right._Get_current() <=> _Left._Get_current();
}
#endif // defined(__cpp_impl_three_way_comparison) && defined(__cpp_lib_concepts)
#endif // __cpp_lib_concepts

template <class _BidIt1, class _BidIt2>
_NODISCARD _CONSTEXPR17 auto operator-(const reverse_iterator<_BidIt1>& _Left, const reverse_iterator<_BidIt2>& _Right)
Expand Down Expand Up @@ -4103,12 +4103,12 @@ _NODISCARD _CONSTEXPR17 bool operator==(const move_iterator<_Iter1>& _Left, cons
#endif // __cpp_lib_concepts
{ return _Left.base() == _Right.base(); }

#if !_HAS_CXX20 || __cpp_impl_three_way_comparison < 201902L
#if !_HAS_CXX20
template <class _Iter1, class _Iter2>
_NODISCARD _CONSTEXPR17 bool operator!=(const move_iterator<_Iter1>& _Left, const move_iterator<_Iter2>& _Right) {
return !(_Left == _Right);
}
#endif // !_HAS_CXX20 || __cpp_impl_three_way_comparison < 201902L
#endif // !_HAS_CXX20

template <class _Iter1, class _Iter2>
_NODISCARD _CONSTEXPR17 bool operator<(const move_iterator<_Iter1>& _Left, const move_iterator<_Iter2>& _Right)
Expand Down Expand Up @@ -4148,13 +4148,13 @@ _NODISCARD _CONSTEXPR17 bool operator>=(const move_iterator<_Iter1>& _Left, cons
#endif // __cpp_lib_concepts
{ return !(_Left < _Right); }

#if defined(__cpp_impl_three_way_comparison) && defined(__cpp_lib_concepts)
#ifdef __cpp_lib_concepts
template <class _Iter1, three_way_comparable_with<_Iter1> _Iter2>
_NODISCARD constexpr compare_three_way_result_t<_Iter1, _Iter2> operator<=>(
const move_iterator<_Iter1>& _Left, const move_iterator<_Iter2>& _Right) {
return _Left.base() <=> _Right.base();
}
#endif // defined(__cpp_impl_three_way_comparison) && defined(__cpp_lib_concepts)
#endif // __cpp_lib_concepts

template <class _Iter1, class _Iter2>
_NODISCARD _CONSTEXPR17 auto operator-(const move_iterator<_Iter1>& _Left, const move_iterator<_Iter2>& _Right)
Expand Down Expand Up @@ -4195,21 +4195,6 @@ namespace _Unreachable_sentinel_detail {
_NODISCARD friend constexpr bool operator==(const unreachable_sentinel_t&, const _Winc&) noexcept {
return false;
}
#if !defined(__cpp_impl_three_way_comparison) || __cpp_impl_three_way_comparison < 201902L
template <weakly_incrementable _Winc>
_NODISCARD friend constexpr bool operator==(const _Winc&, const unreachable_sentinel_t&) noexcept {
return false;
}

template <weakly_incrementable _Winc>
_NODISCARD friend constexpr bool operator!=(const unreachable_sentinel_t&, const _Winc&) noexcept {
return true;
}
template <weakly_incrementable _Winc>
_NODISCARD friend constexpr bool operator!=(const _Winc&, const unreachable_sentinel_t&) noexcept {
return true;
}
#endif // !defined(__cpp_impl_three_way_comparison) || __cpp_impl_three_way_comparison < 201902L
};
} // namespace _Unreachable_sentinel_detail
struct unreachable_sentinel_t : _Unreachable_sentinel_detail::_Base {}; // TRANSITION, /permissive-
Expand Down Expand Up @@ -5236,7 +5221,7 @@ _NODISCARD bool lexicographical_compare(
}
#endif // _HAS_CXX17

#if defined(__cpp_impl_three_way_comparison) && defined(__cpp_lib_concepts)
#ifdef __cpp_lib_concepts
// FUNCTION TEMPLATE lexicographical_compare_three_way
template <class _InIt1, class _InIt2, class _Cmp>
_NODISCARD constexpr auto lexicographical_compare_three_way(
Expand Down Expand Up @@ -5294,7 +5279,7 @@ _NODISCARD constexpr auto lexicographical_compare_three_way(
_InIt1 _First1, _InIt1 _Last1, _InIt2 _First2, _InIt2 _Last2) {
return _STD lexicographical_compare_three_way(_First1, _Last1, _First2, _Last2, compare_three_way{});
}
#endif // defined(__cpp_impl_three_way_comparison) && defined(__cpp_lib_concepts)
#endif // __cpp_lib_concepts

// FUNCTION TEMPLATE find
template <class _Ty>
Expand Down
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