[libcxx] r329460 - Implement P0768r1: Library support for the Spaceship Operator.

Eric Fiselier via cfe-commits cfe-commits at lists.llvm.org
Fri Apr 6 22:40:40 PDT 2018


On Fri, Apr 6, 2018 at 10:50 PM, Richard Smith <richard at metafoo.co.uk>
wrote:

> On Fri, 6 Apr 2018, 21:04 Eric Fiselier via cfe-commits, <
> cfe-commits at lists.llvm.org> wrote:
>
>>
>>
>> On Fri, Apr 6, 2018 at 4:00 PM, Richard Smith <richard at metafoo.co.uk>
>> wrote:
>>
>>> On 6 April 2018 at 14:37, Eric Fiselier via cfe-commits <
>>> cfe-commits at lists.llvm.org> wrote:
>>>
>>>> Author: ericwf
>>>> Date: Fri Apr  6 14:37:23 2018
>>>> New Revision: 329460
>>>>
>>>> URL: http://llvm.org/viewvc/llvm-project?rev=329460&view=rev
>>>> Log:
>>>> Implement P0768r1: Library support for the Spaceship Operator.
>>>>
>>>> this patch adds the <compare> header and implements all of it
>>>> except for [comp.alg].
>>>>
>>>> As I understand it, the header is needed by the compiler in
>>>> when implementing the semantics of operator<=>. For that reason
>>>> I feel it's important to land this header early, despite
>>>> all compilers lacking support.
>>>>
>>>> Added:
>>>>     libcxx/trunk/include/compare
>>>>     libcxx/trunk/test/libcxx/language.support/cmp/
>>>>     libcxx/trunk/test/libcxx/language.support/cmp/version.pass.cpp
>>>>     libcxx/trunk/test/std/language.support/cmp/
>>>>     libcxx/trunk/test/std/language.support/cmp/cmp.common/
>>>>     libcxx/trunk/test/std/language.support/cmp/cmp.
>>>> common/common_comparison_category.pass.cpp
>>>>     libcxx/trunk/test/std/language.support/cmp/cmp.partialord/
>>>>     libcxx/trunk/test/std/language.support/cmp/cmp.
>>>> partialord/partialord.pass.cpp
>>>>     libcxx/trunk/test/std/language.support/cmp/cmp.strongeq/
>>>>     libcxx/trunk/test/std/language.support/cmp/cmp.
>>>> strongeq/cmp.strongeq.pass.cpp
>>>>     libcxx/trunk/test/std/language.support/cmp/cmp.strongord/
>>>>     libcxx/trunk/test/std/language.support/cmp/cmp.
>>>> strongord/strongord.pass.cpp
>>>>     libcxx/trunk/test/std/language.support/cmp/cmp.weakeq/
>>>>     libcxx/trunk/test/std/language.support/cmp/cmp.
>>>> weakeq/cmp.weakeq.pass.cpp
>>>>     libcxx/trunk/test/std/language.support/cmp/cmp.weakord/
>>>>     libcxx/trunk/test/std/language.support/cmp/cmp.
>>>> weakord/weakord.pass.cpp
>>>> Modified:
>>>>     libcxx/trunk/include/CMakeLists.txt
>>>>     libcxx/trunk/include/__config
>>>>     libcxx/trunk/include/module.modulemap
>>>>     libcxx/trunk/test/libcxx/double_include.sh.cpp
>>>>     libcxx/trunk/test/support/test_macros.h
>>>>
>>>> Modified: libcxx/trunk/include/CMakeLists.txt
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/
>>>> CMakeLists.txt?rev=329460&r1=329459&r2=329460&view=diff
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/include/CMakeLists.txt (original)
>>>> +++ libcxx/trunk/include/CMakeLists.txt Fri Apr  6 14:37:23 2018
>>>> @@ -77,5 +77,4 @@ if (LIBCXX_INSTALL_HEADERS)
>>>>      add_custom_target(install-libcxx-headers DEPENDS
>>>> install-cxx-headers)
>>>>      add_custom_target(install-libcxx-headers-stripped DEPENDS
>>>> install-cxx-headers-stripped)
>>>>    endif()
>>>> -
>>>>  endif()
>>>>
>>>> Modified: libcxx/trunk/include/__config
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/_
>>>> _config?rev=329460&r1=329459&r2=329460&view=diff
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/include/__config (original)
>>>> +++ libcxx/trunk/include/__config Fri Apr  6 14:37:23 2018
>>>> @@ -1196,6 +1196,11 @@ _LIBCPP_FUNC_VIS extern "C" void __sanit
>>>>  #define _LIBCPP_HAS_NO_COROUTINES
>>>>  #endif
>>>>
>>>> +// FIXME: Correct this macro when either (A) a feature test macro for
>>>> the
>>>> +// spaceship operator is provided, or (B) a compiler provides a
>>>> complete
>>>> +// implementation.
>>>> +#define _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
>>>> +
>>>>  // Decide whether to use availability macros.
>>>>  #if !defined(_LIBCPP_BUILDING_LIBRARY) &&
>>>>           \
>>>>      !defined(_LIBCPP_DISABLE_AVAILABILITY) &&
>>>>           \
>>>>
>>>> Added: libcxx/trunk/include/compare
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/
>>>> compare?rev=329460&view=auto
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/include/compare (added)
>>>> +++ libcxx/trunk/include/compare Fri Apr  6 14:37:23 2018
>>>> @@ -0,0 +1,679 @@
>>>> +// -*- C++ -*-
>>>> +//===-------------------------- compare ------------------------------
>>>> -----===//
>>>> +//
>>>> +//                     The LLVM Compiler Infrastructure
>>>> +//
>>>> +// This file is dual licensed under the MIT and the University of
>>>> Illinois Open
>>>> +// Source Licenses. See LICENSE.TXT for details.
>>>> +//
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +
>>>> +#ifndef _LIBCPP_COMPARE
>>>> +#define _LIBCPP_COMPARE
>>>> +
>>>> +/*
>>>> +    compare synopsis
>>>> +
>>>> +namespace std {
>>>> +  // [cmp.categories], comparison category types
>>>> +  class weak_equality;
>>>> +  class strong_equality;
>>>> +  class partial_ordering;
>>>> +  class weak_ordering;
>>>> +  class strong_ordering;
>>>> +
>>>> +  // named comparison functions
>>>> +  constexpr bool is_eq  (weak_equality cmp) noexcept    { return cmp
>>>> == 0; }
>>>> +  constexpr bool is_neq (weak_equality cmp) noexcept    { return cmp
>>>> != 0; }
>>>> +  constexpr bool is_lt  (partial_ordering cmp) noexcept { return cmp <
>>>> 0; }
>>>> +  constexpr bool is_lteq(partial_ordering cmp) noexcept { return cmp
>>>> <= 0; }
>>>> +  constexpr bool is_gt  (partial_ordering cmp) noexcept { return cmp >
>>>> 0; }
>>>> +  constexpr bool is_gteq(partial_ordering cmp) noexcept { return cmp
>>>> >= 0; }
>>>> +
>>>> +  // [cmp.common], common comparison category type
>>>> +  template<class... Ts>
>>>> +  struct common_comparison_category {
>>>> +    using type = see below;
>>>> +  };
>>>> +  template<class... Ts>
>>>> +    using common_comparison_category_t = typename
>>>> common_comparison_category<Ts...>::type;
>>>> +
>>>> +  // [cmp.alg], comparison algorithms
>>>> +  template<class T> constexpr strong_ordering strong_order(const T& a,
>>>> const T& b);
>>>> +  template<class T> constexpr weak_ordering weak_order(const T& a,
>>>> const T& b);
>>>> +  template<class T> constexpr partial_ordering partial_order(const T&
>>>> a, const T& b);
>>>> +  template<class T> constexpr strong_equality strong_equal(const T& a,
>>>> const T& b);
>>>> +  template<class T> constexpr weak_equality weak_equal(const T& a,
>>>> const T& b);
>>>> +}
>>>> +*/
>>>> +
>>>> +#include <__config>
>>>> +#include <type_traits>
>>>> +#include <array>
>>>> +
>>>> +#ifndef _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER
>>>> +#pragma GCC system_header
>>>> +#endif
>>>> +
>>>> +_LIBCPP_BEGIN_NAMESPACE_STD
>>>> +
>>>> +#if _LIBCPP_STD_VER > 17
>>>> +
>>>> +// exposition only
>>>> +enum class _LIBCPP_ENUM_VIS _EqResult : unsigned char {
>>>> +  __zero = 0,
>>>> +  __equal = __zero,
>>>> +  __equiv = __equal,
>>>> +  __nonequal = 1,
>>>> +  __nonequiv = __nonequal
>>>> +};
>>>> +
>>>> +enum class _LIBCPP_ENUM_VIS _OrdResult : signed char {
>>>> +  __less = -1,
>>>> +  __greater = 1
>>>> +};
>>>> +
>>>> +enum class _LIBCPP_ENUM_VIS _NCmpResult : signed char {
>>>> +  __unordered = -127
>>>> +};
>>>> +
>>>> +struct _CmpUnspecifiedType;
>>>> +using _CmpUnspecifiedParam = void (_CmpUnspecifiedType::*)();
>>>>
>>>
>>> FYI, I've been planning to add a __zero_type to the compiler for this (a
>>> type that can only be initialized by a literal zero, not e.g. by nullptr).
>>> Looks like that would be easy to retrofit here once it's available.
>>>
>>
>> Awesome :-)
>>
>>
>>>
>>> +
>>>> +class  weak_equality {
>>>> +  _LIBCPP_INLINE_VISIBILITY
>>>> +  constexpr explicit weak_equality(_EqResult __val) noexcept :
>>>> __value_(__val) {}
>>>> +
>>>> +public:
>>>> +  static const weak_equality equivalent;
>>>> +  static const weak_equality nonequivalent;
>>>> +
>>>> +  friend constexpr bool operator==(weak_equality __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator==(_CmpUnspecifiedParam,
>>>> weak_equality __v) noexcept;
>>>> +  friend constexpr bool operator!=(weak_equality __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator!=(_CmpUnspecifiedParam,
>>>> weak_equality __v) noexcept;
>>>> +
>>>> +#ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
>>>> +  friend constexpr weak_equality operator<=>(weak_equality __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr weak_equality operator<=>(_CmpUnspecifiedParam,
>>>> weak_equality __v) noexcept;
>>>> +#endif
>>>> +
>>>> +private:
>>>> +  _EqResult __value_;
>>>> +};
>>>> +
>>>> +_LIBCPP_INLINE_VAR constexpr weak_equality weak_equality::equivalent(_
>>>> EqResult::__equiv);
>>>> +_LIBCPP_INLINE_VAR constexpr weak_equality
>>>> weak_equality::nonequivalent(_EqResult::__nonequiv);
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +inline constexpr bool operator==(weak_equality __v,
>>>> _CmpUnspecifiedParam) noexcept {
>>>> +  return __v.__value_ == _EqResult::__zero;
>>>> +}
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +inline constexpr bool operator==(_CmpUnspecifiedParam, weak_equality
>>>> __v) noexcept {
>>>> +  return __v.__value_ == _EqResult::__zero;
>>>> +}
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +inline constexpr bool operator!=(weak_equality __v,
>>>> _CmpUnspecifiedParam) noexcept {
>>>> +  return __v.__value_ != _EqResult::__zero;
>>>> +}
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +inline constexpr bool operator!=(_CmpUnspecifiedParam, weak_equality
>>>> __v) noexcept {
>>>> +  return __v.__value_ != _EqResult::__zero;
>>>> +}
>>>> +
>>>> +#ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +inline constexpr weak_equality operator<=>(weak_equality __v,
>>>> _CmpUnspecifiedParam) noexcept {
>>>> +  return __v;
>>>> +}
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +inline constexpr weak_equality operator<=>(_CmpUnspecifiedParam,
>>>> weak_equality __v) noexcept {
>>>> +  return __v;
>>>> +}
>>>> +#endif
>>>> +
>>>> +class strong_equality {
>>>> +  _LIBCPP_INLINE_VISIBILITY
>>>> +  explicit constexpr strong_equality(_EqResult __val) noexcept :
>>>> __value_(__val) {}
>>>> +
>>>> +public:
>>>> +  static const strong_equality equal;
>>>> +  static const strong_equality nonequal;
>>>> +  static const strong_equality equivalent;
>>>> +  static const strong_equality nonequivalent;
>>>> +
>>>> +  // conversion
>>>> +  constexpr operator weak_equality() const noexcept {
>>>> +    return __value_ == _EqResult::__zero ? weak_equality::equivalent
>>>> +          : weak_equality::nonequivalent;
>>>> +  }
>>>> +
>>>> +  // comparisons
>>>> +  friend constexpr bool operator==(strong_equality __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator!=(strong_equality __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator==(_CmpUnspecifiedParam,
>>>> strong_equality __v) noexcept;
>>>> +  friend constexpr bool operator!=(_CmpUnspecifiedParam,
>>>> strong_equality __v) noexcept;
>>>> +
>>>> +#ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
>>>> +  friend constexpr strong_equality operator<=>(strong_equality __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr strong_equality operator<=>(_CmpUnspecifiedParam,
>>>> strong_equality __v) noexcept;
>>>> +#endif
>>>> +private:
>>>> +  _EqResult __value_;
>>>> +};
>>>> +
>>>> +_LIBCPP_INLINE_VAR constexpr strong_equality strong_equality::equal(_
>>>> EqResult::__equal);
>>>> +_LIBCPP_INLINE_VAR constexpr strong_equality
>>>> strong_equality::nonequal(_EqResult::__nonequal);
>>>> +_LIBCPP_INLINE_VAR constexpr strong_equality
>>>> strong_equality::equivalent(_EqResult::__equiv);
>>>> +_LIBCPP_INLINE_VAR constexpr strong_equality strong_equality::
>>>> nonequivalent(_EqResult::__nonequiv);
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator==(strong_equality __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__value_ == _EqResult::__zero;
>>>> +}
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator==(_CmpUnspecifiedParam, strong_equality __v)
>>>> noexcept {
>>>> +  return __v.__value_ == _EqResult::__zero;
>>>> +}
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator!=(strong_equality __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__value_ != _EqResult::__zero;
>>>> +}
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator!=(_CmpUnspecifiedParam, strong_equality __v)
>>>> noexcept {
>>>> +  return __v.__value_ != _EqResult::__zero;
>>>> +}
>>>> +
>>>> +#ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr strong_equality operator<=>(strong_equality __v,
>>>> _CmpUnspecifiedParam) noexcept {
>>>> +  return __v;
>>>> +}
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr strong_equality operator<=>(_CmpUnspecifiedParam,
>>>> strong_equality __v) noexcept {
>>>> +  return __v;
>>>> +}
>>>> +#endif // _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
>>>> +
>>>> +class partial_ordering {
>>>> +  using _ValueT = signed char;
>>>> +
>>>> +  _LIBCPP_INLINE_VISIBILITY
>>>> +  explicit constexpr partial_ordering(_EqResult __v) noexcept
>>>> +      : __value_(_ValueT(__v)) {}
>>>> +
>>>> +  _LIBCPP_INLINE_VISIBILITY
>>>> +  explicit constexpr partial_ordering(_OrdResult __v) noexcept
>>>> +      : __value_(_ValueT(__v)) {}
>>>> +
>>>> +  _LIBCPP_INLINE_VISIBILITY
>>>> +  explicit constexpr partial_ordering(_NCmpResult __v) noexcept
>>>> +      : __value_(_ValueT(__v)) {}
>>>> +
>>>> +  constexpr bool __is_ordered() const noexcept {
>>>> +    return __value_ != _ValueT(_NCmpResult::__unordered);
>>>> +  }
>>>> +public:
>>>> +  // valid values
>>>> +  static const partial_ordering less;
>>>> +  static const partial_ordering equivalent;
>>>> +  static const partial_ordering greater;
>>>> +  static const partial_ordering unordered;
>>>> +
>>>> +  // conversion
>>>> +  constexpr operator weak_equality() const noexcept {
>>>> +    return __value_ == 0 ? weak_equality::equivalent :
>>>> weak_equality::nonequivalent;
>>>> +  }
>>>> +
>>>> +  // comparisons
>>>> +  friend constexpr bool operator==(partial_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator!=(partial_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator< (partial_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator<=(partial_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator> (partial_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator>=(partial_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator==(_CmpUnspecifiedParam,
>>>> partial_ordering __v) noexcept;
>>>> +  friend constexpr bool operator!=(_CmpUnspecifiedParam,
>>>> partial_ordering __v) noexcept;
>>>> +  friend constexpr bool operator< (_CmpUnspecifiedParam,
>>>> partial_ordering __v) noexcept;
>>>> +  friend constexpr bool operator<=(_CmpUnspecifiedParam,
>>>> partial_ordering __v) noexcept;
>>>> +  friend constexpr bool operator> (_CmpUnspecifiedParam,
>>>> partial_ordering __v) noexcept;
>>>> +  friend constexpr bool operator>=(_CmpUnspecifiedParam,
>>>> partial_ordering __v) noexcept;
>>>> +
>>>> +#ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
>>>> +  friend constexpr partial_ordering operator<=>(partial_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr partial_ordering operator<=>(_CmpUnspecifiedParam,
>>>> partial_ordering __v) noexcept;
>>>> +#endif
>>>> +
>>>> +private:
>>>> +  _ValueT __value_;
>>>> +};
>>>> +
>>>> +_LIBCPP_INLINE_VAR constexpr partial_ordering partial_ordering::less(_
>>>> OrdResult::__less);
>>>> +_LIBCPP_INLINE_VAR constexpr partial_ordering
>>>> partial_ordering::equivalent(_EqResult::__equiv);
>>>> +_LIBCPP_INLINE_VAR constexpr partial_ordering
>>>> partial_ordering::greater(_OrdResult::__greater);
>>>> +_LIBCPP_INLINE_VAR constexpr partial_ordering
>>>> partial_ordering::unordered(_NCmpResult ::__unordered);
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator==(partial_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__is_ordered() && __v.__value_ == 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator< (partial_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__is_ordered() && __v.__value_ < 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator<=(partial_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__is_ordered() && __v.__value_ <= 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator> (partial_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__is_ordered() && __v.__value_ > 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator>=(partial_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__is_ordered() && __v.__value_ >= 0;
>>>> +}
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator==(_CmpUnspecifiedParam, partial_ordering __v)
>>>> noexcept {
>>>> +  return __v.__is_ordered() && 0 == __v.__value_;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator< (_CmpUnspecifiedParam, partial_ordering __v)
>>>> noexcept {
>>>> +  return __v.__is_ordered() && 0 < __v.__value_;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator<=(_CmpUnspecifiedParam, partial_ordering __v)
>>>> noexcept {
>>>> +  return __v.__is_ordered() && 0 <= __v.__value_;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator> (_CmpUnspecifiedParam, partial_ordering __v)
>>>> noexcept {
>>>> +  return __v.__is_ordered() && 0 > __v.__value_;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator>=(_CmpUnspecifiedParam, partial_ordering __v)
>>>> noexcept {
>>>> +  return __v.__is_ordered() && 0 >= __v.__value_;
>>>> +}
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator!=(partial_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return !__v.__is_ordered() || __v.__value_ != 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator!=(_CmpUnspecifiedParam, partial_ordering __v)
>>>> noexcept {
>>>> +  return !__v.__is_ordered() || __v.__value_ != 0;
>>>> +}
>>>> +
>>>> +#ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr partial_ordering operator<=>(partial_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept {
>>>> +  return __v;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr partial_ordering operator<=>(_CmpUnspecifiedParam,
>>>> partial_ordering __v) noexcept {
>>>> +  return __v < 0 ? partial_ordering::greater : (__v > 0 ?
>>>> partial_ordering::less : __v);
>>>> +}
>>>> +#endif // _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
>>>> +
>>>> +class weak_ordering {
>>>> +  using _ValueT = signed char;
>>>> +
>>>> +  _LIBCPP_INLINE_VISIBILITY
>>>> +  explicit constexpr weak_ordering(_EqResult __v) noexcept :
>>>> __value_(_ValueT(__v)) {}
>>>> +  _LIBCPP_INLINE_VISIBILITY
>>>> +  explicit constexpr weak_ordering(_OrdResult __v) noexcept :
>>>> __value_(_ValueT(__v)) {}
>>>> +
>>>> +public:
>>>> +  static const weak_ordering less;
>>>> +  static const weak_ordering equivalent;
>>>> +  static const weak_ordering greater;
>>>> +
>>>> +  // conversions
>>>> +  _LIBCPP_INLINE_VISIBILITY
>>>> +  constexpr operator weak_equality() const noexcept {
>>>> +    return __value_ == 0 ? weak_equality::equivalent
>>>> +                         : weak_equality::nonequivalent;
>>>> +  }
>>>> +
>>>> +  _LIBCPP_INLINE_VISIBILITY
>>>> +  constexpr operator partial_ordering() const noexcept {
>>>> +    return __value_ == 0 ? partial_ordering::equivalent
>>>> +        : (__value_ < 0 ? partial_ordering::less :
>>>> partial_ordering::greater);
>>>> +  }
>>>> +
>>>> +  // comparisons
>>>> +  friend constexpr bool operator==(weak_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator!=(weak_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator< (weak_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator<=(weak_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator> (weak_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator>=(weak_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator==(_CmpUnspecifiedParam,
>>>> weak_ordering __v) noexcept;
>>>> +  friend constexpr bool operator!=(_CmpUnspecifiedParam,
>>>> weak_ordering __v) noexcept;
>>>> +  friend constexpr bool operator< (_CmpUnspecifiedParam, weak_ordering
>>>> __v) noexcept;
>>>> +  friend constexpr bool operator<=(_CmpUnspecifiedParam,
>>>> weak_ordering __v) noexcept;
>>>> +  friend constexpr bool operator> (_CmpUnspecifiedParam, weak_ordering
>>>> __v) noexcept;
>>>> +  friend constexpr bool operator>=(_CmpUnspecifiedParam,
>>>> weak_ordering __v) noexcept;
>>>> +
>>>> +#ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
>>>> +  friend constexpr weak_ordering operator<=>(weak_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr weak_ordering operator<=>(_CmpUnspecifiedParam,
>>>> weak_ordering __v) noexcept;
>>>> +#endif
>>>> +
>>>> +private:
>>>> +  _ValueT __value_;
>>>> +};
>>>> +
>>>> +_LIBCPP_INLINE_VAR constexpr weak_ordering weak_ordering::less(_
>>>> OrdResult::__less);
>>>> +_LIBCPP_INLINE_VAR constexpr weak_ordering weak_ordering::equivalent(_
>>>> EqResult::__equiv);
>>>> +_LIBCPP_INLINE_VAR constexpr weak_ordering weak_ordering::greater(_
>>>> OrdResult::__greater);
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator==(weak_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__value_ == 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator!=(weak_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__value_ != 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator< (weak_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__value_ < 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator<=(weak_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__value_ <= 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator> (weak_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__value_ > 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator>=(weak_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__value_ >= 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator==(_CmpUnspecifiedParam, weak_ordering __v)
>>>> noexcept {
>>>> +  return 0 == __v.__value_;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator!=(_CmpUnspecifiedParam, weak_ordering __v)
>>>> noexcept {
>>>> +  return 0 != __v.__value_;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator< (_CmpUnspecifiedParam, weak_ordering __v)
>>>> noexcept {
>>>> +  return 0 < __v.__value_;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator<=(_CmpUnspecifiedParam, weak_ordering __v)
>>>> noexcept {
>>>> +  return 0 <= __v.__value_;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator> (_CmpUnspecifiedParam, weak_ordering __v)
>>>> noexcept {
>>>> +  return 0 > __v.__value_;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator>=(_CmpUnspecifiedParam, weak_ordering __v)
>>>> noexcept {
>>>> +  return 0 >= __v.__value_;
>>>> +}
>>>> +
>>>> +#ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr weak_ordering operator<=>(weak_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept {
>>>> +  return __v;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr weak_ordering operator<=>(_CmpUnspecifiedParam,
>>>> weak_ordering __v) noexcept {
>>>> +  return __v < 0 ? weak_ordering::greater : (__v > 0 ?
>>>> weak_ordering::less : __v);
>>>> +}
>>>> +#endif // _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
>>>> +
>>>> +class strong_ordering {
>>>> +  using _ValueT = signed char;
>>>> +
>>>> +  _LIBCPP_INLINE_VISIBILITY
>>>> +  explicit constexpr strong_ordering(_EqResult __v) noexcept :
>>>> __value_(_ValueT(__v)) {}
>>>> +  _LIBCPP_INLINE_VISIBILITY
>>>> +  explicit constexpr strong_ordering(_OrdResult __v) noexcept :
>>>> __value_(_ValueT(__v)) {}
>>>> +
>>>> +public:
>>>> +  static const strong_ordering less;
>>>> +  static const strong_ordering equal;
>>>> +  static const strong_ordering equivalent;
>>>> +  static const strong_ordering greater;
>>>> +
>>>> +  // conversions
>>>> +  _LIBCPP_INLINE_VISIBILITY
>>>> +  constexpr operator weak_equality() const noexcept {
>>>> +    return __value_ == 0 ? weak_equality::equivalent
>>>> +                         : weak_equality::nonequivalent;
>>>> +  }
>>>> +
>>>> +  _LIBCPP_INLINE_VISIBILITY
>>>> +  constexpr operator strong_equality() const noexcept {
>>>> +    return __value_ == 0 ? strong_equality::equal
>>>> +                         : strong_equality::nonequal;
>>>> +  }
>>>> +
>>>> +  _LIBCPP_INLINE_VISIBILITY
>>>> +  constexpr operator partial_ordering() const noexcept {
>>>> +    return __value_ == 0 ? partial_ordering::equivalent
>>>> +        : (__value_ < 0 ? partial_ordering::less :
>>>> partial_ordering::greater);
>>>> +  }
>>>> +
>>>> +  _LIBCPP_INLINE_VISIBILITY
>>>> +  constexpr operator weak_ordering() const noexcept {
>>>> +    return __value_ == 0 ? weak_ordering::equivalent
>>>> +        : (__value_ < 0 ? weak_ordering::less :
>>>> weak_ordering::greater);
>>>> +  }
>>>> +
>>>> +  // comparisons
>>>> +  friend constexpr bool operator==(strong_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator!=(strong_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator< (strong_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator<=(strong_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator> (strong_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator>=(strong_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr bool operator==(_CmpUnspecifiedParam,
>>>> strong_ordering __v) noexcept;
>>>> +  friend constexpr bool operator!=(_CmpUnspecifiedParam,
>>>> strong_ordering __v) noexcept;
>>>> +  friend constexpr bool operator< (_CmpUnspecifiedParam,
>>>> strong_ordering __v) noexcept;
>>>> +  friend constexpr bool operator<=(_CmpUnspecifiedParam,
>>>> strong_ordering __v) noexcept;
>>>> +  friend constexpr bool operator> (_CmpUnspecifiedParam,
>>>> strong_ordering __v) noexcept;
>>>> +  friend constexpr bool operator>=(_CmpUnspecifiedParam,
>>>> strong_ordering __v) noexcept;
>>>> +
>>>> +#ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
>>>> +  friend constexpr strong_ordering operator<=>(strong_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept;
>>>> +  friend constexpr strong_ordering operator<=>(_CmpUnspecifiedParam,
>>>> strong_ordering __v) noexcept;
>>>> +#endif
>>>> +
>>>> +private:
>>>> +  _ValueT __value_;
>>>> +};
>>>> +
>>>> +_LIBCPP_INLINE_VAR constexpr strong_ordering strong_ordering::less(_
>>>> OrdResult::__less);
>>>> +_LIBCPP_INLINE_VAR constexpr strong_ordering strong_ordering::equal(_
>>>> EqResult::__equal);
>>>> +_LIBCPP_INLINE_VAR constexpr strong_ordering
>>>> strong_ordering::equivalent(_EqResult::__equiv);
>>>> +_LIBCPP_INLINE_VAR constexpr strong_ordering strong_ordering::greater(_
>>>> OrdResult::__greater);
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator==(strong_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__value_ == 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator!=(strong_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__value_ != 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator< (strong_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__value_ < 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator<=(strong_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__value_ <= 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator> (strong_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__value_ > 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator>=(strong_ordering __v, _CmpUnspecifiedParam)
>>>> noexcept {
>>>> +  return __v.__value_ >= 0;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator==(_CmpUnspecifiedParam, strong_ordering __v)
>>>> noexcept {
>>>> +  return 0 == __v.__value_;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator!=(_CmpUnspecifiedParam, strong_ordering __v)
>>>> noexcept {
>>>> +  return 0 != __v.__value_;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator< (_CmpUnspecifiedParam, strong_ordering __v)
>>>> noexcept {
>>>> +  return 0 < __v.__value_;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator<=(_CmpUnspecifiedParam, strong_ordering __v)
>>>> noexcept {
>>>> +  return 0 <= __v.__value_;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator> (_CmpUnspecifiedParam, strong_ordering __v)
>>>> noexcept {
>>>> +  return 0 > __v.__value_;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool operator>=(_CmpUnspecifiedParam, strong_ordering __v)
>>>> noexcept {
>>>> +  return 0 >= __v.__value_;
>>>> +}
>>>> +
>>>> +#ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr strong_ordering operator<=>(strong_ordering __v,
>>>> _CmpUnspecifiedParam) noexcept {
>>>> +  return __v;
>>>> +}
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr strong_ordering operator<=>(_CmpUnspecifiedParam,
>>>> strong_ordering __v) noexcept {
>>>> +  return __v < 0 ? strong_ordering::greater : (__v > 0 ?
>>>> strong_ordering::less : __v);
>>>> +}
>>>> +#endif // _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
>>>> +
>>>> +// named comparison functions
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool is_eq(weak_equality __cmp) noexcept    { return __cmp
>>>> == 0; }
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool is_neq(weak_equality __cmp) noexcept    { return __cmp
>>>> != 0; }
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool is_lt(partial_ordering __cmp) noexcept { return __cmp <
>>>> 0; }
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool is_lteq(partial_ordering __cmp) noexcept { return __cmp
>>>> <= 0; }
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool is_gt(partial_ordering __cmp) noexcept { return __cmp >
>>>> 0; }
>>>> +
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr bool is_gteq(partial_ordering __cmp) noexcept { return __cmp
>>>> >= 0; }
>>>> +
>>>> +namespace __comp_detail {
>>>> +
>>>> +enum _ClassifyCompCategory : unsigned{
>>>> +  _None,
>>>> +  _WeakEq,
>>>> +  _StrongEq,
>>>> +  _PartialOrd,
>>>> +  _WeakOrd,
>>>> +  _StrongOrd,
>>>> +  _CCC_Size
>>>> +};
>>>> +
>>>> +template <class _Tp>
>>>> +_LIBCPP_INLINE_VISIBILITY
>>>> +constexpr _ClassifyCompCategory __type_to_enum() noexcept {
>>>> +  if (is_same_v<_Tp, weak_equality>)
>>>> +    return _WeakEq;
>>>> +  if (is_same_v<_Tp, strong_equality>)
>>>> +    return _StrongEq;
>>>> +  if (is_same_v<_Tp, partial_ordering>)
>>>> +    return _PartialOrd;
>>>> +  if (is_same_v<_Tp, weak_ordering>)
>>>> +    return _WeakOrd;
>>>> +  if (is_same_v<_Tp, strong_ordering>)
>>>> +    return _StrongOrd;
>>>> +  return _None;
>>>> +}
>>>> +
>>>> +template <size_t _Size>
>>>> +constexpr _ClassifyCompCategory
>>>> +__compute_comp_type(std::array<_ClassifyCompCategory, _Size> __types)
>>>> {
>>>> +  std::array<int, _CCC_Size> __seen = {};
>>>> +  for (auto __type : __types)
>>>> +    ++__seen[__type];
>>>> +  if (__seen[_None])
>>>> +    return _None;
>>>> +  if (__seen[_WeakEq])
>>>> +    return _WeakEq;
>>>> +  if (__seen[_StrongEq] && (__seen[_PartialOrd] || __seen[_WeakOrd]))
>>>> +    return _WeakEq;
>>>> +  if (__seen[_StrongEq])
>>>> +    return _StrongEq;
>>>> +  if (__seen[_PartialOrd])
>>>> +    return _PartialOrd;
>>>> +  if (__seen[_WeakOrd])
>>>> +    return _WeakOrd;
>>>> +  return _StrongOrd;
>>>> +}
>>>>
>>>
>>> Hmm, it'd be nice to ask the compiler to work this out rather than
>>> repeating the algorithm here. For example, something like:
>>>
>>> template<size_t, typename T> struct CCT { friend T operator<=>(const
>>> CCT&, const CCT&); };
>>> template<typename N, typename ...T> struct CCC;
>>> template<size_t ...N, typename ...T> struct CCC : CCT<N, T>... {
>>>   friend auto operator<=>(const CCC&, const CCC&) = default;
>>> };
>>> template<typename ...T> struct common_comparison_category {
>>>   template<typename C> static auto test(int) -> decltype(declval<const
>>> C&>() <=> declval<const C&>());
>>>   template<typename C> static void test(...);
>>>   using type = decltype(test<CCC<std::make_index_sequence<sizeof...(T)>,
>>> T...>>(0));
>>> }
>>>
>>> ... should allow you to ask the compiler for the common comparison type.
>>>
>>
>> Looks good to me. Once we actually have a compiler I can do that with
>> I'll make the change.
>> For now I think it's preferable to have a working implementation.
>>
>> FYI, I have an almost complete implementation of [expr.spaceship].
>>
>> I was about to start making ExprConstant work, but I think that requires
>> a new AST node to
>> represent three-way comparisons. Since <=> builtins return a DeclRefExpr
>> for the appropriate
>> comparison category type member (ex. strong_equality::equal), and we
>> can't build these
>> in ExprConstant so it seems appropriate to build them earlier and store
>> them in the
>> operator expression node (I suspect this problem also arises during
>> CodeGen).
>>
>> Does that seem reasonable?
>>
>
> My vague plan had been to add functionality to ASTConstant to look up (and
> cache) those members, and query that from CodeGen and ExprConstant (and
> also from Sema just as a validity check). I'd prefer not to store the same
> list of members on all <=> nodes of the same type.
>

OK. That seems a lot better :-)


>
> Have you thought at all about how to represent the rewritten forms of
> operators using <=>?
>

I haven't really looked too far past [expr.spaceship] and the library spec,
so no. What are your main concerns?
I've experienced problems in SemaCoroutine producing reasonable diagnostics
for rewritten expressions.



>
> +
>>>> +template <class ..._Ts>
>>>> +constexpr auto __get_comp_type() {
>>>> +  using _CCC = _ClassifyCompCategory;
>>>> +  constexpr array<_CCC, sizeof...(_Ts)> __type_kinds{__comp_detail::__
>>>> type_to_enum<_Ts>()...};
>>>> +  constexpr _CCC _Cat = sizeof...(_Ts) == 0 ? _StrongOrd
>>>> +      : __compute_comp_type(__type_kinds);
>>>> +  if constexpr (_Cat == _None)
>>>> +    return ((void)0);
>>>>
>>>
>>> void() is a more idiomatic way to write this. (Incidentally, this case
>>> seems like a bug in the library spec to me -- common_comparison_category<...>::type
>>> should not exist in the case where there is no common comparison type, for
>>> consistency with the other traits.)
>>>
>>
>> I forgot about `void()`. Thanks.
>>
>> I'll look into the library spec tomorrow, and probably file an issue.
>>
>>
>>>
>>>
>>>> +  else if constexpr (_Cat == _WeakEq)
>>>> +    return weak_equality::equivalent;
>>>> +  else if constexpr (_Cat == _StrongEq)
>>>> +    return strong_equality::equivalent;
>>>> +  else if constexpr (_Cat == _PartialOrd)
>>>> +    return partial_ordering::equivalent;
>>>> +  else if constexpr (_Cat == _WeakOrd)
>>>> +    return weak_ordering::equivalent;
>>>> +  else if constexpr (_Cat == _StrongOrd)
>>>> +    return strong_ordering::equivalent;
>>>> +  else
>>>> +    static_assert(_Cat != _Cat, "unhandled case");
>>>> +}
>>>> +} // namespace __comp_detail
>>>> +
>>>> +// [cmp.common], common comparison category type
>>>> +template<class... _Ts>
>>>> +struct _LIBCPP_TEMPLATE_VIS common_comparison_category {
>>>> +  using type = decltype(__comp_detail::__get_comp_type<_Ts...>());
>>>> +};
>>>> +
>>>> +template<class... _Ts>
>>>> +using common_comparison_category_t = typename
>>>> common_comparison_category<_Ts...>::type;
>>>> +
>>>> +// [cmp.alg], comparison algorithms
>>>> +// TODO: unimplemented
>>>> +template<class _Tp> constexpr strong_ordering strong_order(const _Tp&
>>>> __lhs, const _Tp& __rhs);
>>>> +template<class _Tp> constexpr weak_ordering weak_order(const _Tp&
>>>> __lhs, const _Tp& __rhs);
>>>> +template<class _Tp> constexpr partial_ordering partial_order(const
>>>> _Tp& __lhs, const _Tp& __rhs);
>>>> +template<class _Tp> constexpr strong_equality strong_equal(const _Tp&
>>>> __lhs, const _Tp& __rhs);
>>>> +template<class _Tp> constexpr weak_equality weak_equal(const _Tp&
>>>> __lhs, const _Tp& __rhs);
>>>> +
>>>> +#endif // _LIBCPP_STD_VER > 17
>>>> +
>>>> +_LIBCPP_END_NAMESPACE_STD
>>>> +
>>>> +#endif // _LIBCPP_COMPARE
>>>>
>>>> Modified: libcxx/trunk/include/module.modulemap
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/
>>>> module.modulemap?rev=329460&r1=329459&r2=329460&view=diff
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/include/module.modulemap (original)
>>>> +++ libcxx/trunk/include/module.modulemap Fri Apr  6 14:37:23 2018
>>>> @@ -243,6 +243,10 @@ module std [system] {
>>>>      header "codecvt"
>>>>      export *
>>>>    }
>>>> +  module compare {
>>>> +    header "compare"
>>>> +    export *
>>>> +  }
>>>>    module complex {
>>>>      header "complex"
>>>>      export *
>>>>
>>>> Modified: libcxx/trunk/test/libcxx/double_include.sh.cpp
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/
>>>> libcxx/double_include.sh.cpp?rev=329460&r1=329459&r2=329460&view=diff
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/test/libcxx/double_include.sh.cpp (original)
>>>> +++ libcxx/trunk/test/libcxx/double_include.sh.cpp Fri Apr  6 14:37:23
>>>> 2018
>>>> @@ -41,6 +41,7 @@
>>>>  #include <clocale>
>>>>  #include <cmath>
>>>>  #include <codecvt>
>>>> +#include <compare>
>>>>  #include <complex>
>>>>  #include <complex.h>
>>>>  #include <condition_variable>
>>>>
>>>> Added: libcxx/trunk/test/libcxx/language.support/cmp/version.pass.cpp
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/
>>>> libcxx/language.support/cmp/version.pass.cpp?rev=329460&view=auto
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/test/libcxx/language.support/cmp/version.pass.cpp
>>>> (added)
>>>> +++ libcxx/trunk/test/libcxx/language.support/cmp/version.pass.cpp Fri
>>>> Apr  6 14:37:23 2018
>>>> @@ -0,0 +1,20 @@
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +//
>>>> +//                     The LLVM Compiler Infrastructure
>>>> +//
>>>> +// This file is dual licensed under the MIT and the University of
>>>> Illinois Open
>>>> +// Source Licenses. See LICENSE.TXT for details.
>>>> +//
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +
>>>> +// <compare>
>>>> +
>>>> +#include <compare>
>>>> +
>>>> +#ifndef _LIBCPP_VERSION
>>>> +#error _LIBCPP_VERSION not defined
>>>> +#endif
>>>> +
>>>> +int main()
>>>> +{
>>>> +}
>>>>
>>>> Added: libcxx/trunk/test/std/language.support/cmp/cmp.
>>>> common/common_comparison_category.pass.cpp
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/
>>>> language.support/cmp/cmp.common/common_comparison_
>>>> category.pass.cpp?rev=329460&view=auto
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/test/std/language.support/cmp/cmp.
>>>> common/common_comparison_category.pass.cpp (added)
>>>> +++ libcxx/trunk/test/std/language.support/cmp/cmp.
>>>> common/common_comparison_category.pass.cpp Fri Apr  6 14:37:23 2018
>>>> @@ -0,0 +1,93 @@
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +//
>>>> +//                     The LLVM Compiler Infrastructure
>>>> +//
>>>> +// This file is dual licensed under the MIT and the University of
>>>> Illinois Open
>>>> +// Source Licenses. See LICENSE.TXT for details.
>>>> +//
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +
>>>> +// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
>>>> +
>>>> +// <compare>
>>>> +
>>>> +// template <class ...Ts> struct common_comparison_category
>>>> +// template <class ...Ts> using common_comparison_category_t
>>>> +
>>>> +
>>>> +#include <compare>
>>>> +#include <type_traits>
>>>> +#include <cassert>
>>>> +
>>>> +#include "test_macros.h"
>>>> +
>>>> +const volatile void* volatile sink;
>>>> +
>>>> +template <class Expect, class ...Args>
>>>> +void test_cat() {
>>>> +  using Cat = std::common_comparison_category<Args...>;
>>>> +  using CatT = typename Cat::type;
>>>> +  static_assert(std::is_same<CatT, std::common_comparison_category_t<Args...>>::value,
>>>> "");
>>>> +  static_assert(std::is_same<CatT, Expect>::value, "expected
>>>> different category");
>>>> +};
>>>> +
>>>> +
>>>> +// [class.spaceship]p4: The 'common comparison type' U of a
>>>> possibly-empty list
>>>> +//   of 'n' types T0, T1, ..., TN, is defined as follows:
>>>> +int main() {
>>>> +  using WE = std::weak_equality;
>>>> +  using SE = std::strong_equality;
>>>> +  using PO = std::partial_ordering;
>>>> +  using WO = std::weak_ordering;
>>>> +  using SO = std::strong_ordering;
>>>> +
>>>> +  // [class.spaceship]p4.1: If any Ti is not a comparison category
>>>> tpe, U is void.
>>>> +  {
>>>> +    test_cat<void, void>();
>>>> +    test_cat<void, int*>();
>>>> +    test_cat<void, SO&>();
>>>> +    test_cat<void, SO const>();
>>>> +    test_cat<void, SO*>();
>>>> +    test_cat<void, SO, void, SO>();
>>>> +  }
>>>> +
>>>> +  // [class.spaceship]p4.2: Otherwise, if at least on Ti is
>>>> +  // std::weak_equality, or at least one Ti is std::strong_equality
>>>> and at least
>>>> +  // one Tj is std::partial_ordering or std::weak_ordering, U is
>>>> std::weak_equality
>>>> +  {
>>>> +    test_cat<WE, WE>();
>>>> +    test_cat<WE, SO, WE, SO>();
>>>> +    test_cat<WE, SE, SO, PO>();
>>>> +    test_cat<WE, WO, SO, SE>();
>>>> +  }
>>>> +
>>>> +  // [class.spaceship]p4.3: Otherwise, if at least one Ti is
>>>> std::strong_equality,
>>>> +  // U is std::strong_equality
>>>> +  {
>>>> +    test_cat<SE, SE>();
>>>> +    test_cat<SE, SO, SE, SO>();
>>>> +  }
>>>> +
>>>> +  // [class.spaceship]p4.4: Otherwise, if at least one Ti is
>>>> std::partial_ordering,
>>>> +  // U is std::partial_ordering
>>>> +  {
>>>> +    test_cat<PO, PO>();
>>>> +    test_cat<PO, SO, PO, SO>();
>>>> +    test_cat<PO, WO, PO, SO>();
>>>> +  }
>>>> +
>>>> +  // [class.spaceship]p4.5: Otherwise, if at least one Ti is
>>>> std::weak_ordering,
>>>> +  // U is std::weak_ordering
>>>> +  {
>>>> +    test_cat<WO, WO>();
>>>> +    test_cat<WO, SO, WO, SO>();
>>>> +  }
>>>> +
>>>> +  // [class.spaceship]p4.6: Otherwise, U is std::strong_ordering.
>>>> [Note: in
>>>> +  // particular this is the result when n is 0. -- end note]
>>>> +  {
>>>> +    test_cat<SO>(); // empty type list
>>>> +    test_cat<SO, SO>();
>>>> +    test_cat<SO, SO, SO>();
>>>> +  }
>>>> +}
>>>>
>>>> Added: libcxx/trunk/test/std/language.support/cmp/cmp.
>>>> partialord/partialord.pass.cpp
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/
>>>> language.support/cmp/cmp.partialord/partialord.pass.
>>>> cpp?rev=329460&view=auto
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/test/std/language.support/cmp/cmp.partialord/partialord.pass.cpp
>>>> (added)
>>>> +++ libcxx/trunk/test/std/language.support/cmp/cmp.partialord/partialord.pass.cpp
>>>> Fri Apr  6 14:37:23 2018
>>>> @@ -0,0 +1,164 @@
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +//
>>>> +//                     The LLVM Compiler Infrastructure
>>>> +//
>>>> +// This file is dual licensed under the MIT and the University of
>>>> Illinois Open
>>>> +// Source Licenses. See LICENSE.TXT for details.
>>>> +//
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +
>>>> +// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
>>>> +
>>>> +// <compare>
>>>> +
>>>> +// class partial_ordering
>>>> +
>>>> +
>>>> +#include <compare>
>>>> +#include <type_traits>
>>>> +#include <cassert>
>>>> +
>>>> +#include "test_macros.h"
>>>> +
>>>> +const volatile void* volatile sink;
>>>> +
>>>> +void test_static_members() {
>>>> +  DoNotOptimize(&std::partial_ordering::less);
>>>> +  DoNotOptimize(&std::partial_ordering::equivalent);
>>>> +  DoNotOptimize(&std::partial_ordering::greater);
>>>> +  DoNotOptimize(&std::partial_ordering::unordered);
>>>> +}
>>>> +
>>>> +void test_signatures() {
>>>> +  auto& Eq = std::partial_ordering::equivalent;
>>>> +
>>>> +  ASSERT_NOEXCEPT(Eq == 0);
>>>> +  ASSERT_NOEXCEPT(0 == Eq);
>>>> +  ASSERT_NOEXCEPT(Eq != 0);
>>>> +  ASSERT_NOEXCEPT(0 != Eq);
>>>> +  ASSERT_NOEXCEPT(0 < Eq);
>>>> +  ASSERT_NOEXCEPT(Eq < 0);
>>>> +  ASSERT_NOEXCEPT(0 <= Eq);
>>>> +  ASSERT_NOEXCEPT(Eq <= 0);
>>>> +  ASSERT_NOEXCEPT(0 > Eq);
>>>> +  ASSERT_NOEXCEPT(Eq > 0);
>>>> +  ASSERT_NOEXCEPT(0 >= Eq);
>>>> +  ASSERT_NOEXCEPT(Eq >= 0);
>>>> +#ifndef TEST_HAS_NO_SPACESHIP_OPERATOR
>>>> +  ASSERT_NOEXCEPT(0 <=> Eq);
>>>> +  ASSERT_NOEXCEPT(Eq <=> 0);
>>>> +  ASSERT_SAME_TYPE(decltype(Eq <=> 0), std::partial_ordering);
>>>> +  ASSERT_SAME_TYPE(decltype(0 <=> Eq), std::partial_ordering);
>>>> +#endif
>>>> +}
>>>> +
>>>> +constexpr bool test_conversion() {
>>>> +  static_assert(std::is_convertible<const std::partial_ordering,
>>>> std::weak_equality>::value, "");
>>>> +  { // value == 0
>>>> +    auto V = std::partial_ordering::equivalent;
>>>> +    std::weak_equality WV = V;
>>>> +    assert(WV == 0);
>>>> +  }
>>>> +  std::partial_ordering TestCases[] = {
>>>> +      std::partial_ordering::less,
>>>> +      std::partial_ordering::greater,
>>>> +      std::partial_ordering::unordered
>>>> +  };
>>>> +  for (auto V : TestCases)
>>>> +  { // value != 0
>>>> +    std::weak_equality WV = V;
>>>> +    assert(WV != 0);
>>>> +  }
>>>> +  return true;
>>>> +}
>>>> +
>>>> +constexpr bool test_constexpr() {
>>>> +  auto& Eq = std::partial_ordering::equivalent;
>>>> +  auto& Less = std::partial_ordering::less;
>>>> +  auto& Greater = std::partial_ordering::greater;
>>>> +  auto& Unord = std::partial_ordering::unordered;
>>>> +  struct {
>>>> +    std::partial_ordering Value;
>>>> +    bool ExpectEq;
>>>> +    bool ExpectNeq;
>>>> +    bool ExpectLess;
>>>> +    bool ExpectGreater;
>>>> +  } TestCases[] = {
>>>> +      {Eq, true, false, false, false},
>>>> +      {Less, false, true, true, false},
>>>> +      {Greater, false, true, false, true},
>>>> +      {Unord, false, true, false, false}
>>>> +  };
>>>> +  for (auto TC : TestCases) {
>>>> +    auto V = TC.Value;
>>>> +    assert((V == 0) == TC.ExpectEq);
>>>> +    assert((0 == V) == TC.ExpectEq);
>>>> +    assert((V != 0) == TC.ExpectNeq);
>>>> +    assert((0 != V) == TC.ExpectNeq);
>>>> +
>>>> +    assert((V < 0) == TC.ExpectLess);
>>>> +    assert((V > 0) == TC.ExpectGreater);
>>>> +    assert((V <= 0) == (TC.ExpectLess || TC.ExpectEq));
>>>> +    assert((V >= 0) == (TC.ExpectGreater || TC.ExpectEq));
>>>> +
>>>> +    assert((0 < V) == TC.ExpectGreater);
>>>> +    assert((0 > V) == TC.ExpectLess);
>>>> +    assert((0 <= V) == (TC.ExpectGreater || TC.ExpectEq));
>>>> +    assert((0 >= V) == (TC.ExpectLess || TC.ExpectEq));
>>>> +  }
>>>> +#ifndef TEST_HAS_NO_SPACESHIP_OPERATOR
>>>> +  {
>>>> +    std::partial_ordering res = (Eq <=> 0);
>>>> +    ((void)res);
>>>> +    res = (0 <=> Eq);
>>>> +    ((void)res);
>>>> +  }
>>>> +  enum ExpectRes {
>>>> +    ER_Greater,
>>>> +    ER_Less,
>>>> +    ER_Equiv,
>>>> +    ER_Unord
>>>> +  };
>>>> +  struct {
>>>> +    std::partial_ordering Value;
>>>> +    ExpectRes Expect;
>>>> +  } SpaceshipTestCases[] = {
>>>> +      {std::partial_ordering::equivalent, ER_Equiv},
>>>> +      {std::partial_ordering::less, ER_Less},
>>>> +      {std::partial_ordering::greater, ER_Greater},
>>>> +      {std::partial_ordering::unordered, ER_Unord}
>>>> +  };
>>>> +  for (auto TC : SpaceshipTestCases)
>>>> +  {
>>>> +    std::partial_ordering Res = (0 <=> TC.Value);
>>>> +    switch (TC.Expect) {
>>>> +    case ER_Equiv:
>>>> +      assert(Res == 0);
>>>> +      assert(0 == Res);
>>>> +      break;
>>>> +    case ER_Less:
>>>> +      assert(Res < 0);
>>>> +      break;
>>>> +    case ER_Greater:
>>>> +      assert(Res > 0);
>>>> +      break;
>>>> +    case ER_Unord:
>>>> +      assert(Res != 0);
>>>> +      assert(0 != Res);
>>>> +      assert((Res < 0) == false);
>>>> +      assert((Res > 0) == false);
>>>> +      assert((Res == 0) == false);
>>>> +      break;
>>>> +    }
>>>> +  }
>>>> +#endif
>>>> +
>>>> +  return true;
>>>> +}
>>>> +
>>>> +int main() {
>>>> +  test_static_members();
>>>> +  test_signatures();
>>>> +  static_assert(test_conversion(), "conversion test failed");
>>>> +  static_assert(test_constexpr(), "constexpr test failed");
>>>> +}
>>>>
>>>> Added: libcxx/trunk/test/std/language.support/cmp/cmp.
>>>> strongeq/cmp.strongeq.pass.cpp
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/
>>>> language.support/cmp/cmp.strongeq/cmp.strongeq.pass.
>>>> cpp?rev=329460&view=auto
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/test/std/language.support/cmp/cmp.strongeq/cmp.strongeq.pass.cpp
>>>> (added)
>>>> +++ libcxx/trunk/test/std/language.support/cmp/cmp.strongeq/cmp.strongeq.pass.cpp
>>>> Fri Apr  6 14:37:23 2018
>>>> @@ -0,0 +1,96 @@
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +//
>>>> +//                     The LLVM Compiler Infrastructure
>>>> +//
>>>> +// This file is dual licensed under the MIT and the University of
>>>> Illinois Open
>>>> +// Source Licenses. See LICENSE.TXT for details.
>>>> +//
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +
>>>> +// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
>>>> +
>>>> +// <compare>
>>>> +
>>>> +// class strong_equality
>>>> +
>>>> +
>>>> +#include <compare>
>>>> +#include <type_traits>
>>>> +#include <cassert>
>>>> +
>>>> +#include "test_macros.h"
>>>> +
>>>> +const volatile void* volatile sink;
>>>> +
>>>> +void test_static_members() {
>>>> +  DoNotOptimize(&std::strong_equality::equal);
>>>> +  DoNotOptimize(&std::strong_equality::nonequal);
>>>> +  DoNotOptimize(&std::strong_equality::equivalent);
>>>> +  DoNotOptimize(&std::strong_equality::nonequivalent);
>>>> +}
>>>> +
>>>> +void test_signatures() {
>>>> +  auto& Eq = std::strong_equality::equivalent;
>>>> +
>>>> +  ASSERT_NOEXCEPT(Eq == 0);
>>>> +  ASSERT_NOEXCEPT(0 == Eq);
>>>> +  ASSERT_NOEXCEPT(Eq != 0);
>>>> +  ASSERT_NOEXCEPT(0 != Eq);
>>>> +#ifndef TEST_HAS_NO_SPACESHIP_OPERATOR
>>>> +  ASSERT_NOEXCEPT(0 <=> Eq);
>>>> +  ASSERT_NOEXCEPT(Eq <=> 0);
>>>> +  ASSERT_SAME_TYPE(decltype(Eq <=> 0), std::strong_equality);
>>>> +  ASSERT_SAME_TYPE(decltype(0 <=> Eq), std::strong_equality);
>>>> +#endif
>>>> +}
>>>> +
>>>> +void test_conversion() {
>>>> +  constexpr std::weak_equality res = std::strong_equality::equivalent;
>>>> +  static_assert(res == 0, "");
>>>> +  static_assert(std::is_convertible<const std::strong_equality&,
>>>> +      std::weak_equality>::value, "");
>>>> +  static_assert(res == 0, "expected equal");
>>>> +
>>>> +  constexpr std::weak_equality neq_res = std::strong_equality::
>>>> nonequivalent;
>>>> +  static_assert(neq_res != 0, "expected not equal");
>>>> +}
>>>> +
>>>> +constexpr bool test_constexpr() {
>>>> +  auto& Eq = std::strong_equality::equal;
>>>> +  auto& NEq = std::strong_equality::nonequal;
>>>> +  auto& Equiv = std::strong_equality::equivalent;
>>>> +  auto& NEquiv = std::strong_equality::nonequivalent;
>>>> +  assert((Eq == 0) == true);
>>>> +  assert((0 == Eq) == true);
>>>> +  assert((Equiv == 0) == true);
>>>> +  assert((0 == Equiv) == true);
>>>> +  assert((NEq == 0) == false);
>>>> +  assert((0 == NEq) == false);
>>>> +  assert((NEquiv == 0) == false);
>>>> +  assert((0 == NEquiv) == false);
>>>> +
>>>> +  assert((Eq != 0) == false);
>>>> +  assert((0 != Eq) == false);
>>>> +  assert((Equiv != 0) == false);
>>>> +  assert((0 != Equiv) == false);
>>>> +  assert((NEq != 0) == true);
>>>> +  assert((0 != NEq) == true);
>>>> +  assert((NEquiv != 0) == true);
>>>> +  assert((0 != NEquiv) == true);
>>>> +
>>>> +#ifndef TEST_HAS_NO_SPACESHIP_OPERATOR
>>>> +  std::strong_equality res = (Eq <=> 0);
>>>> +  ((void)res);
>>>> +  res = (0 <=> Eq);
>>>> +  ((void)res);
>>>> +#endif
>>>> +
>>>> +  return true;
>>>> +}
>>>> +
>>>> +int main() {
>>>> +  test_static_members();
>>>> +  test_signatures();
>>>> +  test_conversion();
>>>> +  static_assert(test_constexpr(), "constexpr test failed");
>>>> +}
>>>>
>>>> Added: libcxx/trunk/test/std/language.support/cmp/cmp.
>>>> strongord/strongord.pass.cpp
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/
>>>> language.support/cmp/cmp.strongord/strongord.pass.cpp?
>>>> rev=329460&view=auto
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/test/std/language.support/cmp/cmp.strongord/strongord.pass.cpp
>>>> (added)
>>>> +++ libcxx/trunk/test/std/language.support/cmp/cmp.strongord/strongord.pass.cpp
>>>> Fri Apr  6 14:37:23 2018
>>>> @@ -0,0 +1,212 @@
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +//
>>>> +//                     The LLVM Compiler Infrastructure
>>>> +//
>>>> +// This file is dual licensed under the MIT and the University of
>>>> Illinois Open
>>>> +// Source Licenses. See LICENSE.TXT for details.
>>>> +//
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +
>>>> +// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
>>>> +
>>>> +// <compare>
>>>> +
>>>> +// class strong_ordering
>>>> +
>>>> +
>>>> +#include <compare>
>>>> +#include <type_traits>
>>>> +#include <cassert>
>>>> +
>>>> +#include "test_macros.h"
>>>> +
>>>> +const volatile void* volatile sink;
>>>> +
>>>> +void test_static_members() {
>>>> +  DoNotOptimize(&std::strong_ordering::less);
>>>> +  DoNotOptimize(&std::strong_ordering::equal);
>>>> +  DoNotOptimize(&std::strong_ordering::equivalent);
>>>> +  DoNotOptimize(&std::strong_ordering::greater);
>>>> +}
>>>> +
>>>> +void test_signatures() {
>>>> +  auto& Eq = std::strong_ordering::equivalent;
>>>> +
>>>> +  ASSERT_NOEXCEPT(Eq == 0);
>>>> +  ASSERT_NOEXCEPT(0 == Eq);
>>>> +  ASSERT_NOEXCEPT(Eq != 0);
>>>> +  ASSERT_NOEXCEPT(0 != Eq);
>>>> +  ASSERT_NOEXCEPT(0 < Eq);
>>>> +  ASSERT_NOEXCEPT(Eq < 0);
>>>> +  ASSERT_NOEXCEPT(0 <= Eq);
>>>> +  ASSERT_NOEXCEPT(Eq <= 0);
>>>> +  ASSERT_NOEXCEPT(0 > Eq);
>>>> +  ASSERT_NOEXCEPT(Eq > 0);
>>>> +  ASSERT_NOEXCEPT(0 >= Eq);
>>>> +  ASSERT_NOEXCEPT(Eq >= 0);
>>>> +#ifndef TEST_HAS_NO_SPACESHIP_OPERATOR
>>>> +  ASSERT_NOEXCEPT(0 <=> Eq);
>>>> +  ASSERT_NOEXCEPT(Eq <=> 0);
>>>> +  ASSERT_SAME_TYPE(decltype(Eq <=> 0), std::strong_ordering);
>>>> +  ASSERT_SAME_TYPE(decltype(0 <=> Eq), std::strong_ordering);
>>>> +#endif
>>>> +}
>>>> +
>>>> +constexpr bool test_conversion() {
>>>> +  static_assert(std::is_convertible<const std::strong_ordering&,
>>>> +      std::weak_equality>::value, "");
>>>> +  { // value == 0
>>>> +    auto V = std::strong_ordering::equivalent;
>>>> +    std::weak_equality WV = V;
>>>> +    assert(WV == 0);
>>>> +  }
>>>> +  std::strong_ordering WeakTestCases[] = {
>>>> +      std::strong_ordering::less,
>>>> +      std::strong_ordering::greater,
>>>> +  };
>>>> +  for (auto V : WeakTestCases)
>>>> +  { // value != 0
>>>> +    std::weak_equality WV = V;
>>>> +    assert(WV != 0);
>>>> +  }
>>>> +  static_assert(std::is_convertible<const std::strong_ordering&,
>>>> +      std::strong_equality>::value, "");
>>>> +  { // value == 0
>>>> +    auto V = std::strong_ordering::equivalent;
>>>> +    std::strong_equality WV = V;
>>>> +    assert(WV == 0);
>>>> +  }
>>>> +  { // value == 0
>>>> +    auto V = std::strong_ordering::equal;
>>>> +    std::strong_equality WV = V;
>>>> +    assert(WV == 0);
>>>> +  }
>>>> +  std::strong_ordering StrongTestCases[] = {
>>>> +      std::strong_ordering::less,
>>>> +      std::strong_ordering::greater,
>>>> +  };
>>>> +  for (auto V : StrongTestCases)
>>>> +  { // value != 0
>>>> +    std::strong_equality WV = V;
>>>> +    assert(WV != 0);
>>>> +  }
>>>> +
>>>> +  static_assert(std::is_convertible<const std::strong_ordering&,
>>>> +      std::partial_ordering>::value, "");
>>>> +  { // value == 0
>>>> +    auto V = std::strong_ordering::equivalent;
>>>> +    std::partial_ordering WV = V;
>>>> +    assert(WV == 0);
>>>> +  }
>>>> +  { // value < 0
>>>> +    auto V = std::strong_ordering::less;
>>>> +    std::partial_ordering WV = V;
>>>> +    assert(WV < 0);
>>>> +  }
>>>> +  { // value > 0
>>>> +    auto V = std::strong_ordering::greater;
>>>> +    std::partial_ordering WV = V;
>>>> +    assert(WV > 0);
>>>> +  }
>>>> +
>>>> +  static_assert(std::is_convertible<const std::strong_ordering&,
>>>> +      std::weak_ordering>::value, "");
>>>> +  { // value == 0
>>>> +    auto V = std::strong_ordering::equivalent;
>>>> +    std::weak_ordering WV = V;
>>>> +    assert(WV == 0);
>>>> +  }
>>>> +  { // value < 0
>>>> +    auto V = std::strong_ordering::less;
>>>> +    std::weak_ordering WV = V;
>>>> +    assert(WV < 0);
>>>> +  }
>>>> +  { // value > 0
>>>> +    auto V = std::strong_ordering::greater;
>>>> +    std::weak_ordering WV = V;
>>>> +    assert(WV > 0);
>>>> +  }
>>>> +  return true;
>>>> +}
>>>> +
>>>> +constexpr bool test_constexpr() {
>>>> +  auto& Eq = std::strong_ordering::equal;
>>>> +  auto& Equiv = std::strong_ordering::equivalent;
>>>> +  auto& Less = std::strong_ordering::less;
>>>> +  auto& Greater = std::strong_ordering::greater;
>>>> +  struct {
>>>> +    std::strong_ordering Value;
>>>> +    bool ExpectEq;
>>>> +    bool ExpectNeq;
>>>> +    bool ExpectLess;
>>>> +    bool ExpectGreater;
>>>> +  } TestCases[] = {
>>>> +      {Eq, true, false, false, false},
>>>> +      {Equiv, true, false, false, false},
>>>> +      {Less, false, true, true, false},
>>>> +      {Greater, false, true, false, true},
>>>> +  };
>>>> +  for (auto TC : TestCases) {
>>>> +    auto V = TC.Value;
>>>> +    assert((V == 0) == TC.ExpectEq);
>>>> +    assert((0 == V) == TC.ExpectEq);
>>>> +    assert((V != 0) == TC.ExpectNeq);
>>>> +    assert((0 != V) == TC.ExpectNeq);
>>>> +
>>>> +    assert((V < 0) == TC.ExpectLess);
>>>> +    assert((V > 0) == TC.ExpectGreater);
>>>> +    assert((V <= 0) == (TC.ExpectLess || TC.ExpectEq));
>>>> +    assert((V >= 0) == (TC.ExpectGreater || TC.ExpectEq));
>>>> +
>>>> +    assert((0 < V) == TC.ExpectGreater);
>>>> +    assert((0 > V) == TC.ExpectLess);
>>>> +    assert((0 <= V) == (TC.ExpectGreater || TC.ExpectEq));
>>>> +    assert((0 >= V) == (TC.ExpectLess || TC.ExpectEq));
>>>> +  }
>>>> +#ifndef TEST_HAS_NO_SPACESHIP_OPERATOR
>>>> +  {
>>>> +    std::strong_ordering res = (Eq <=> 0);
>>>> +    ((void)res);
>>>> +    res = (0 <=> Eq);
>>>> +    ((void)res);
>>>> +  }
>>>> +  enum ExpectRes {
>>>> +    ER_Greater,
>>>> +    ER_Less,
>>>> +    ER_Equiv
>>>> +  };
>>>> +  struct {
>>>> +    std::strong_ordering Value;
>>>> +    ExpectRes Expect;
>>>> +  } SpaceshipTestCases[] = {
>>>> +      {std::strong_ordering::equivalent, ER_Equiv},
>>>> +      {std::strong_ordering::less, ER_Less},
>>>> +      {std::strong_ordering::greater, ER_Greater},
>>>> +  };
>>>> +  for (auto TC : SpaceshipTestCases)
>>>> +  {
>>>> +    std::strong_ordering Res = (0 <=> TC.Value);
>>>> +    switch (TC.Expect) {
>>>> +    case ER_Equiv:
>>>> +      assert(Res == 0);
>>>> +      assert(0 == Res);
>>>> +      break;
>>>> +    case ER_Less:
>>>> +      assert(Res < 0);
>>>> +      break;
>>>> +    case ER_Greater:
>>>> +      assert(Res > 0);
>>>> +      break;
>>>> +    }
>>>> +  }
>>>> +#endif
>>>> +
>>>> +  return true;
>>>> +}
>>>> +
>>>> +int main() {
>>>> +  test_static_members();
>>>> +  test_signatures();
>>>> +  static_assert(test_conversion(), "conversion test failed");
>>>> +  static_assert(test_constexpr(), "constexpr test failed");
>>>> +}
>>>>
>>>> Added: libcxx/trunk/test/std/language.support/cmp/cmp.
>>>> weakeq/cmp.weakeq.pass.cpp
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/
>>>> language.support/cmp/cmp.weakeq/cmp.weakeq.pass.cpp?
>>>> rev=329460&view=auto
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/test/std/language.support/cmp/cmp.weakeq/cmp.weakeq.pass.cpp
>>>> (added)
>>>> +++ libcxx/trunk/test/std/language.support/cmp/cmp.weakeq/cmp.weakeq.pass.cpp
>>>> Fri Apr  6 14:37:23 2018
>>>> @@ -0,0 +1,70 @@
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +//
>>>> +//                     The LLVM Compiler Infrastructure
>>>> +//
>>>> +// This file is dual licensed under the MIT and the University of
>>>> Illinois Open
>>>> +// Source Licenses. See LICENSE.TXT for details.
>>>> +//
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +
>>>> +// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
>>>> +
>>>> +// <compare>
>>>> +
>>>> +// class weak_equality
>>>> +
>>>> +
>>>> +#include <compare>
>>>> +#include <cassert>
>>>> +#include "test_macros.h"
>>>> +
>>>> +const volatile void* volatile sink;
>>>> +
>>>> +void test_static_members() {
>>>> +  DoNotOptimize(&std::weak_equality::equivalent);
>>>> +  DoNotOptimize(&std::weak_equality::nonequivalent);
>>>> +}
>>>> +
>>>> +void test_signatures() {
>>>> +  auto& Eq = std::weak_equality::equivalent;
>>>> +
>>>> +  ASSERT_NOEXCEPT(Eq == 0);
>>>> +  ASSERT_NOEXCEPT(0 == Eq);
>>>> +  ASSERT_NOEXCEPT(Eq != 0);
>>>> +  ASSERT_NOEXCEPT(0 != Eq);
>>>> +#ifndef TEST_HAS_NO_SPACESHIP_OPERATOR
>>>> +  ASSERT_NOEXCEPT(0 <=> Eq);
>>>> +  ASSERT_NOEXCEPT(Eq <=> 0);
>>>> +  ASSERT_SAME_TYPE(decltype(Eq <=> 0), std::weak_equality);
>>>> +  ASSERT_SAME_TYPE(decltype(0 <=> Eq), std::weak_equality);
>>>> +#endif
>>>> +}
>>>> +
>>>> +constexpr bool test_constexpr() {
>>>> +  auto& Eq = std::weak_equality::equivalent;
>>>> +  auto& NEq = std::weak_equality::nonequivalent;
>>>> +  assert((Eq == 0) == true);
>>>> +  assert((0 == Eq) == true);
>>>> +  assert((NEq == 0) == false);
>>>> +  assert((0 == NEq) == false);
>>>> +
>>>> +  assert((Eq != 0) == false);
>>>> +  assert((0 != Eq) == false);
>>>> +  assert((NEq != 0) == true);
>>>> +  assert((0 != NEq) == true);
>>>> +
>>>> +#ifndef TEST_HAS_NO_SPACESHIP_OPERATOR
>>>> +  std::weak_equality res = (Eq <=> 0);
>>>> +  ((void)res);
>>>> +  res = (0 <=> Eq);
>>>> +  ((void)res);
>>>> +#endif
>>>> +
>>>> +  return true;
>>>> +}
>>>> +
>>>> +int main() {
>>>> +  test_static_members();
>>>> +  test_signatures();
>>>> +  static_assert(test_constexpr(), "constexpr test failed");
>>>> +}
>>>>
>>>> Added: libcxx/trunk/test/std/language.support/cmp/cmp.
>>>> weakord/weakord.pass.cpp
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/
>>>> language.support/cmp/cmp.weakord/weakord.pass.cpp?rev=329460&view=auto
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/test/std/language.support/cmp/cmp.weakord/weakord.pass.cpp
>>>> (added)
>>>> +++ libcxx/trunk/test/std/language.support/cmp/cmp.weakord/weakord.pass.cpp
>>>> Fri Apr  6 14:37:23 2018
>>>> @@ -0,0 +1,169 @@
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +//
>>>> +//                     The LLVM Compiler Infrastructure
>>>> +//
>>>> +// This file is dual licensed under the MIT and the University of
>>>> Illinois Open
>>>> +// Source Licenses. See LICENSE.TXT for details.
>>>> +//
>>>> +//===------------------------------------------------------
>>>> ----------------===//
>>>> +
>>>> +// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
>>>> +
>>>> +// <compare>
>>>> +
>>>> +// class weak_ordering
>>>> +
>>>> +
>>>> +#include <compare>
>>>> +#include <type_traits>
>>>> +#include <cassert>
>>>> +
>>>> +#include "test_macros.h"
>>>> +
>>>> +const volatile void* volatile sink;
>>>> +
>>>> +void test_static_members() {
>>>> +  DoNotOptimize(&std::weak_ordering::less);
>>>> +  DoNotOptimize(&std::weak_ordering::equivalent);
>>>> +  DoNotOptimize(&std::weak_ordering::greater);
>>>> +}
>>>> +
>>>> +void test_signatures() {
>>>> +  auto& Eq = std::weak_ordering::equivalent;
>>>> +
>>>> +  ASSERT_NOEXCEPT(Eq == 0);
>>>> +  ASSERT_NOEXCEPT(0 == Eq);
>>>> +  ASSERT_NOEXCEPT(Eq != 0);
>>>> +  ASSERT_NOEXCEPT(0 != Eq);
>>>> +  ASSERT_NOEXCEPT(0 < Eq);
>>>> +  ASSERT_NOEXCEPT(Eq < 0);
>>>> +  ASSERT_NOEXCEPT(0 <= Eq);
>>>> +  ASSERT_NOEXCEPT(Eq <= 0);
>>>> +  ASSERT_NOEXCEPT(0 > Eq);
>>>> +  ASSERT_NOEXCEPT(Eq > 0);
>>>> +  ASSERT_NOEXCEPT(0 >= Eq);
>>>> +  ASSERT_NOEXCEPT(Eq >= 0);
>>>> +#ifndef TEST_HAS_NO_SPACESHIP_OPERATOR
>>>> +  ASSERT_NOEXCEPT(0 <=> Eq);
>>>> +  ASSERT_NOEXCEPT(Eq <=> 0);
>>>> +  ASSERT_SAME_TYPE(decltype(Eq <=> 0), std::weak_ordering);
>>>> +  ASSERT_SAME_TYPE(decltype(0 <=> Eq), std::weak_ordering);
>>>> +#endif
>>>> +}
>>>> +
>>>> +constexpr bool test_conversion() {
>>>> +  static_assert(std::is_convertible<const std::weak_ordering&,
>>>> +      std::weak_equality>::value, "");
>>>> +  { // value == 0
>>>> +    auto V = std::weak_ordering::equivalent;
>>>> +    std::weak_equality WV = V;
>>>> +    assert(WV == 0);
>>>> +  }
>>>> +  std::weak_ordering WeakTestCases[] = {
>>>> +      std::weak_ordering::less,
>>>> +      std::weak_ordering::greater,
>>>> +  };
>>>> +  for (auto V : WeakTestCases)
>>>> +  { // value != 0
>>>> +    std::weak_equality WV = V;
>>>> +    assert(WV != 0);
>>>> +  }
>>>> +  static_assert(std::is_convertible<const std::weak_ordering&,
>>>> +      std::partial_ordering>::value, "");
>>>> +  { // value == 0
>>>> +    auto V = std::weak_ordering::equivalent;
>>>> +    std::partial_ordering WV = V;
>>>> +    assert(WV == 0);
>>>> +  }
>>>> +  { // value < 0
>>>> +    auto V = std::weak_ordering::less;
>>>> +    std::partial_ordering WV = V;
>>>> +    assert(WV < 0);
>>>> +  }
>>>> +  { // value > 0
>>>> +    auto V = std::weak_ordering::greater;
>>>> +    std::partial_ordering WV = V;
>>>> +    assert(WV > 0);
>>>> +  }
>>>> +  return true;
>>>> +}
>>>> +
>>>> +constexpr bool test_constexpr() {
>>>> +  auto& Eq = std::weak_ordering::equivalent;
>>>> +  auto& Less = std::weak_ordering::less;
>>>> +  auto& Greater = std::weak_ordering::greater;
>>>> +  struct {
>>>> +    std::weak_ordering Value;
>>>> +    bool ExpectEq;
>>>> +    bool ExpectNeq;
>>>> +    bool ExpectLess;
>>>> +    bool ExpectGreater;
>>>> +  } TestCases[] = {
>>>> +      {Eq, true, false, false, false},
>>>> +      {Less, false, true, true, false},
>>>> +      {Greater, false, true, false, true},
>>>> +  };
>>>> +  for (auto TC : TestCases) {
>>>> +    auto V = TC.Value;
>>>> +    assert((V == 0) == TC.ExpectEq);
>>>> +    assert((0 == V) == TC.ExpectEq);
>>>> +    assert((V != 0) == TC.ExpectNeq);
>>>> +    assert((0 != V) == TC.ExpectNeq);
>>>> +
>>>> +    assert((V < 0) == TC.ExpectLess);
>>>> +    assert((V > 0) == TC.ExpectGreater);
>>>> +    assert((V <= 0) == (TC.ExpectLess || TC.ExpectEq));
>>>> +    assert((V >= 0) == (TC.ExpectGreater || TC.ExpectEq));
>>>> +
>>>> +    assert((0 < V) == TC.ExpectGreater);
>>>> +    assert((0 > V) == TC.ExpectLess);
>>>> +    assert((0 <= V) == (TC.ExpectGreater || TC.ExpectEq));
>>>> +    assert((0 >= V) == (TC.ExpectLess || TC.ExpectEq));
>>>> +  }
>>>> +#ifndef TEST_HAS_NO_SPACESHIP_OPERATOR
>>>> +  {
>>>> +    std::weak_ordering res = (Eq <=> 0);
>>>> +    ((void)res);
>>>> +    res = (0 <=> Eq);
>>>> +    ((void)res);
>>>> +  }
>>>> +  enum ExpectRes {
>>>> +    ER_Greater,
>>>> +    ER_Less,
>>>> +    ER_Equiv
>>>> +  };
>>>> +  struct {
>>>> +    std::weak_ordering Value;
>>>> +    ExpectRes Expect;
>>>> +  } SpaceshipTestCases[] = {
>>>> +      {std::weak_ordering::equivalent, ER_Equiv},
>>>> +      {std::weak_ordering::less, ER_Less},
>>>> +      {std::weak_ordering::greater, ER_Greater},
>>>> +  };
>>>> +  for (auto TC : SpaceshipTestCases)
>>>> +  {
>>>> +    std::weak_ordering Res = (0 <=> TC.Value);
>>>> +    switch (TC.Expect) {
>>>> +    case ER_Equiv:
>>>> +      assert(Res == 0);
>>>> +      assert(0 == Res);
>>>> +      break;
>>>> +    case ER_Less:
>>>> +      assert(Res < 0);
>>>> +      break;
>>>> +    case ER_Greater:
>>>> +      assert(Res > 0);
>>>> +      break;
>>>> +    }
>>>> +  }
>>>> +#endif
>>>> +
>>>> +  return true;
>>>> +}
>>>> +
>>>> +int main() {
>>>> +  test_static_members();
>>>> +  test_signatures();
>>>> +  static_assert(test_conversion(), "conversion test failed");
>>>> +  static_assert(test_constexpr(), "constexpr test failed");
>>>> +}
>>>>
>>>> Modified: libcxx/trunk/test/support/test_macros.h
>>>> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/
>>>> support/test_macros.h?rev=329460&r1=329459&r2=329460&view=diff
>>>> ============================================================
>>>> ==================
>>>> --- libcxx/trunk/test/support/test_macros.h (original)
>>>> +++ libcxx/trunk/test/support/test_macros.h Fri Apr  6 14:37:23 2018
>>>> @@ -169,6 +169,11 @@
>>>>  #define TEST_SAFE_STATIC
>>>>  #endif
>>>>
>>>> +// FIXME: Fix this feature check when either (A) a compiler provides a
>>>> complete
>>>> +// implementation, or (b) a feature check macro is specified
>>>> +#define TEST_HAS_NO_SPACESHIP_OPERATOR
>>>> +
>>>> +
>>>>  #if TEST_STD_VER < 11
>>>>  #define ASSERT_NOEXCEPT(...)
>>>>  #define ASSERT_NOT_NOEXCEPT(...)
>>>>
>>>>
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>>>>
>>>
>>>
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