[libc++][modularisation] Split <compare> into internal headers

[cjdb]

This should be mostly ready to go (I'm a bit surprised we only need two headers). Two bits of feedback.

1. Blocking: Please add these to the module map. The ranges.__ranges submodule should give you guidance on how to make the compare.__compare submodule. I'll LGTM once this is done.
2. Non-blocking: I'd appreciate it if you could change [NFC] in your commit summary to [modularisation].

[rarutyun]

In D106107#2881766, @cjdb wrote:

This should be mostly ready to go (I'm a bit surprised we only need two headers). Two bits of feedback.

1. Blocking: Please add these to the module map. The ranges.__ranges submodule should give you guidance on how to make the compare.__compare submodule. I'll LGTM once this is done.
2. Non-blocking: I'd appreciate it if you could change [NFC] in your commit summary to [modularisation].

Done. Please check if everything correct

libcxx/include/__compare/ordering.h

10

I don't see the reason to create separate header for each ordering, but if you do I can change that.

[rarutyun]

In D106107#2881766, @cjdb wrote:

This should be mostly ready to go (I'm a bit surprised we only need two headers).

Regarding just two headers. I expect them to be more in future because not everything is implemented in <compare> e.g. compare_three_way_result, some CPOs, etc. But for now I don't think it worth it to split ordering.h on separate partial, weak and strong unless you think opposite.

[cjdb]

I'm happy with this once CI passes; @ldionne any thoughts?

libcxx/include/__compare/ordering.h

10

Since they're codependent, I'm fine with this.

[• Quuxplusone]

LGTM mod nits.

libcxx/include/CMakeLists.txt

102–103

a-z plz

libcxx/include/__compare/common_comparison_category.h

10–11

I think our style would make this _LIBCPP___COMPARE_COMMON_COMPARISON_CATEGORY_H — please check some other nested-directory files, and then change it here if I'm right.

13–14

a-z plz

30

If you want, a drive-by whitespace fix to unsigned { would be nice.

libcxx/include/compare

132–133

Is this needed now for some reason? (Historically we seem to have put __undef_macros only in files that actually use min or max as identifiers. If something breaks without these lines, it'd be nice to say in your commit message what it is; and if nothing breaks without these lines, then arguably they shouldn't be here. Although I'm not inclined to actually object.)

libcxx/include/module.modulemap

359–360

a-z plz

[cjdb]

libcxx/include/compare

132–133

This maaaaay have indirectly been my doing. I used to include <__undef_macros> in all my headers before I understood its purpose. I think since then it's just been included in everything by accident at this point. I agree we should remove it, and we should probably action some mass-cleanup in the near future (since I'm apparently taking responsibility for the trend, it makes sense for me to do it).

[rarutyun]

libcxx/include/__compare/common_comparison_category.h

10–11

Yes, you are right. I did it for ordering header but for some reason prefix was missed for this file

libcxx/include/module.modulemap

359–360

Actually I've found another mistake that is more important. `compare module was already there and I needed to just add private headers. Now it's done.

[rarutyun]

clang-format applied

[• Quuxplusone]

One final nit, then ship it!
(Assuming you don't need someone to land this for you. But if you do, please ping me and I can do it.)

libcxx/include/module.modulemap

363–364

These two still need alphabetization between the two of them (i.e., switch their order).

[rarutyun]

libcxx/include/module.modulemap

363–364

:) Done. Sorry for missing that, it's 2:30 am my timezone:)

[ldionne]

LGTM once CI passes, and assuming you did not modify any code (only moving stuff around).

CI appears to be failing right now, so please make sure to have a green run before shipping.

[rarutyun]

In D106107#2910992, @ldionne wrote:

LGTM once CI passes, and assuming you did not modify any code (only moving stuff around).

CI appears to be failing right now, so please make sure to have a green run before shipping.

Yep nothing in the code has changed. Only moving stuff here and there.

[rarutyun]

I figured out what was wrong with "Generated Output" step. I was needed to add generated tests to the commit as well. Previously I didn't know that but currently it is done. Waiting for the CI completion.

I also found the recent change in __get_comp_type function and also applied it to this patch.

[rarutyun]

There is a high probability that CI will be successful. If it's the case I would need somebody to commit this patch for me.

@Quuxplusone, if I remember correctly you volunteered to do that. Could you please help?

Full name: Ruslan Arutyunyan

Thanks.

[• Quuxplusone]

There is a high probability that CI will be successful. If it's the case I would need somebody to commit this patch for me.
@Quuxplusone, if I remember correctly you volunteered to do that. Could you please help?
Full name: Ruslan Arutyunyan

Yes, I can land it. For that I also need your email address (which is probably gettable from Phabricator somehow, but it's not obvious ;)) because a Git committer ID is always of the form Bob Smith <[e-mail]>.

[• Quuxplusone]

For that I also need your email address (which is probably gettable from Phabricator somehow, but it's not obvious ;))

Didn't figure it out from Phab, but the mails sent to the reviews.llvm.org mailing list have it. I'll land this shortly.

libcxx/include/CMakeLists.txt

set(files
   __algorithm/unique.h
   __algorithm/unwrap_iter.h
   __algorithm/upper_bound.h
   __availability
   __bit_reference
   __bits
   __bsd_locale_defaults.h
   __bsd_locale_fallbacks.h
+  __compare/common_comparison_category.h
+  __compare/ordering.h
   __config
   __debug
   __errc
   __format/format_error.h
   __format/format_parse_context.h
   __function_like.h
   __functional_base
   __functional/binary_function.h
   __functional/binary_negate.h
   __functional/bind_front.h

libcxx/include/__compare/common_comparison_category.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP__COMPARE__COMMON_COMPARISON_CATEGORY_H
+#define _LIBCPP__COMPARE__COMMON_COMPARISON_CATEGORY_H
+
+#include <__compare/ordering.h>
+#include <__config>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR)
+
+namespace __comp_detail {
+
+enum _ClassifyCompCategory : unsigned { _None, _PartialOrd, _WeakOrd, _StrongOrd, _CCC_Size };
+
+template <class _Tp>
+_LIBCPP_INLINE_VISIBILITY constexpr _ClassifyCompCategory __type_to_enum() noexcept {
+  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(const _ClassifyCompCategory (&__types)[_Size]) {
+  int __seen[_CCC_Size] = {};
+  for (auto __type : __types)
+    ++__seen[__type];
+  if (__seen[_None])
+    return _None;
+  if (__seen[_PartialOrd])
+    return _PartialOrd;
+  if (__seen[_WeakOrd])
+    return _WeakOrd;
+  return _StrongOrd;
+}
+
+template <class... _Ts>
+constexpr auto __get_comp_type() {
+  using _CCC = _ClassifyCompCategory;
+  constexpr _CCC __type_kinds[] = {_StrongOrd, __type_to_enum<_Ts>()...};
+  constexpr _CCC _Cat = __compute_comp_type(__type_kinds);
+  if constexpr (_Cat == _None)
+    return void();
+  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;
+
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR)
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP__COMPARE__COMMON_COMPARISON_CATEGORY_H

libcxx/include/__compare/ordering.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP__COMPARE_ORDERING_H
+#define _LIBCPP__COMPARE_ORDERING_H
+
+#include <__config>
+#include <type_traits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR)
+// 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 };
+
+class partial_ordering;
+class weak_ordering;
+class strong_ordering;
+
+template <class _Tp, class... _Args>
+inline constexpr bool __one_of_v = (is_same_v<_Tp, _Args> || ...);
+
+struct _CmpUnspecifiedParam {
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEVAL _CmpUnspecifiedParam(int _CmpUnspecifiedParam::*) noexcept {}
+
+  template <class _Tp, class = enable_if_t<!__one_of_v<_Tp, int, partial_ordering, weak_ordering, strong_ordering> > >
+  _CmpUnspecifiedParam(_Tp) = delete;
+};
+
+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;
+
+  // comparisons
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(partial_ordering, partial_ordering) noexcept = default;
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(partial_ordering __v, _CmpUnspecifiedParam) noexcept {
+    return __v.__is_ordered() && __v.__value_ == 0;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<(partial_ordering __v, _CmpUnspecifiedParam) noexcept {
+    return __v.__is_ordered() && __v.__value_ < 0;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(partial_ordering __v, _CmpUnspecifiedParam) noexcept {
+    return __v.__is_ordered() && __v.__value_ <= 0;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>(partial_ordering __v, _CmpUnspecifiedParam) noexcept {
+    return __v.__is_ordered() && __v.__value_ > 0;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(partial_ordering __v, _CmpUnspecifiedParam) noexcept {
+    return __v.__is_ordered() && __v.__value_ >= 0;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<(_CmpUnspecifiedParam, partial_ordering __v) noexcept {
+    return __v.__is_ordered() && 0 < __v.__value_;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(_CmpUnspecifiedParam, partial_ordering __v) noexcept {
+    return __v.__is_ordered() && 0 <= __v.__value_;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>(_CmpUnspecifiedParam, partial_ordering __v) noexcept {
+    return __v.__is_ordered() && 0 > __v.__value_;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(_CmpUnspecifiedParam, partial_ordering __v) noexcept {
+    return __v.__is_ordered() && 0 >= __v.__value_;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr partial_ordering operator<=>(partial_ordering __v,
+                                                                          _CmpUnspecifiedParam) noexcept {
+    return __v;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr partial_ordering operator<=>(_CmpUnspecifiedParam,
+                                                                          partial_ordering __v) noexcept {
+    return __v < 0 ? partial_ordering::greater : (__v > 0 ? partial_ordering::less : __v);
+  }
+
+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);
+
+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;
+
+  _LIBCPP_INLINE_VISIBILITY
+  constexpr operator partial_ordering() const noexcept {
+    return __value_ == 0 ? partial_ordering::equivalent
+                         : (__value_ < 0 ? partial_ordering::less : partial_ordering::greater);
+  }
+
+  // comparisons
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(weak_ordering, weak_ordering) noexcept = default;
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(weak_ordering __v, _CmpUnspecifiedParam) noexcept {
+    return __v.__value_ == 0;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<(weak_ordering __v, _CmpUnspecifiedParam) noexcept {
+    return __v.__value_ < 0;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(weak_ordering __v, _CmpUnspecifiedParam) noexcept {
+    return __v.__value_ <= 0;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>(weak_ordering __v, _CmpUnspecifiedParam) noexcept {
+    return __v.__value_ > 0;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(weak_ordering __v, _CmpUnspecifiedParam) noexcept {
+    return __v.__value_ >= 0;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<(_CmpUnspecifiedParam, weak_ordering __v) noexcept {
+    return 0 < __v.__value_;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(_CmpUnspecifiedParam, weak_ordering __v) noexcept {
+    return 0 <= __v.__value_;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>(_CmpUnspecifiedParam, weak_ordering __v) noexcept {
+    return 0 > __v.__value_;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(_CmpUnspecifiedParam, weak_ordering __v) noexcept {
+    return 0 >= __v.__value_;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr weak_ordering operator<=>(weak_ordering __v,
+                                                                       _CmpUnspecifiedParam) noexcept {
+    return __v;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr weak_ordering operator<=>(_CmpUnspecifiedParam,
+                                                                       weak_ordering __v) noexcept {
+    return __v < 0 ? weak_ordering::greater : (__v > 0 ? weak_ordering::less : __v);
+  }
+
+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);
+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 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
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(strong_ordering, strong_ordering) noexcept = default;
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(strong_ordering __v, _CmpUnspecifiedParam) noexcept {
+    return __v.__value_ == 0;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<(strong_ordering __v, _CmpUnspecifiedParam) noexcept {
+    return __v.__value_ < 0;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(strong_ordering __v, _CmpUnspecifiedParam) noexcept {
+    return __v.__value_ <= 0;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>(strong_ordering __v, _CmpUnspecifiedParam) noexcept {
+    return __v.__value_ > 0;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(strong_ordering __v, _CmpUnspecifiedParam) noexcept {
+    return __v.__value_ >= 0;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<(_CmpUnspecifiedParam, strong_ordering __v) noexcept {
+    return 0 < __v.__value_;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(_CmpUnspecifiedParam, strong_ordering __v) noexcept {
+    return 0 <= __v.__value_;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>(_CmpUnspecifiedParam, strong_ordering __v) noexcept {
+    return 0 > __v.__value_;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(_CmpUnspecifiedParam, strong_ordering __v) noexcept {
+    return 0 >= __v.__value_;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr strong_ordering operator<=>(strong_ordering __v,
+                                                                         _CmpUnspecifiedParam) noexcept {
+    return __v;
+  }
+
+  _LIBCPP_INLINE_VISIBILITY friend constexpr strong_ordering operator<=>(_CmpUnspecifiedParam,
+                                                                         strong_ordering __v) noexcept {
+    return __v < 0 ? strong_ordering::greater : (__v > 0 ? strong_ordering::less : __v);
+  }
+
+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);
+
+// named comparison functions
+_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; }
+
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR)
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP__COMPARE_ORDERING_H

libcxx/include/compare

public:
     friend constexpr bool operator<=(unspecified, strong_ordering v) noexcept;
     friend constexpr bool operator>=(unspecified, strong_ordering v) noexcept;
     friend constexpr strong_ordering operator<=>(strong_ordering v, unspecified) noexcept;
     friend constexpr strong_ordering operator<=>(unspecified, strong_ordering v) noexcept;
   };
 }
 */
 
+#include <__compare/common_comparison_category.h>
+#include <__compare/ordering.h>
 #include <__config>
 #include <type_traits>
 
 #ifndef _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER
 #pragma GCC system_header
 #endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 #if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR)
-// 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
-};
-
-class partial_ordering;
-class weak_ordering;
-class strong_ordering;
-
-template<class _Tp, class... _Args>
-inline constexpr bool __one_of_v = (is_same_v<_Tp, _Args> || ...);
-
-struct _CmpUnspecifiedParam {
-  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEVAL
-  _CmpUnspecifiedParam(int _CmpUnspecifiedParam::*) noexcept {}
-
-  template<class _Tp, class = enable_if_t<!__one_of_v<_Tp, int, partial_ordering, weak_ordering, strong_ordering>>>
-  _CmpUnspecifiedParam(_Tp) = delete;
-};
-
-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;
-
-  // comparisons
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(partial_ordering, partial_ordering) noexcept = default;
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(partial_ordering __v, _CmpUnspecifiedParam) noexcept {
-    return __v.__is_ordered() && __v.__value_ == 0;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator< (partial_ordering __v, _CmpUnspecifiedParam) noexcept {
-    return __v.__is_ordered() && __v.__value_ < 0;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(partial_ordering __v, _CmpUnspecifiedParam) noexcept  {
-    return __v.__is_ordered() && __v.__value_ <= 0;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator> (partial_ordering __v, _CmpUnspecifiedParam) noexcept  {
-    return __v.__is_ordered() && __v.__value_ > 0;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(partial_ordering __v, _CmpUnspecifiedParam) noexcept  {
-    return __v.__is_ordered() && __v.__value_ >= 0;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator< (_CmpUnspecifiedParam, partial_ordering __v) noexcept  {
-    return __v.__is_ordered() && 0 < __v.__value_;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(_CmpUnspecifiedParam, partial_ordering __v) noexcept  {
-    return __v.__is_ordered() && 0 <= __v.__value_;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator> (_CmpUnspecifiedParam, partial_ordering __v) noexcept  {
-    return __v.__is_ordered() && 0 > __v.__value_;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(_CmpUnspecifiedParam, partial_ordering __v) noexcept  {
-    return __v.__is_ordered() && 0 >= __v.__value_;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr partial_ordering operator<=>(partial_ordering __v, _CmpUnspecifiedParam) noexcept  {
-    return __v;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr partial_ordering operator<=>(_CmpUnspecifiedParam, partial_ordering __v) noexcept  {
-    return __v < 0 ? partial_ordering::greater : (__v > 0 ? partial_ordering::less : __v);
-  }
-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);
-
-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;
-
-  _LIBCPP_INLINE_VISIBILITY
-  constexpr operator partial_ordering() const noexcept {
-    return __value_ == 0 ? partial_ordering::equivalent
-        : (__value_ < 0 ? partial_ordering::less : partial_ordering::greater);
-  }
-
-  // comparisons
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(weak_ordering, weak_ordering) noexcept = default;
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(weak_ordering __v, _CmpUnspecifiedParam) noexcept {
-    return __v.__value_ == 0;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator< (weak_ordering __v, _CmpUnspecifiedParam) noexcept {
-    return __v.__value_ < 0;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(weak_ordering __v, _CmpUnspecifiedParam) noexcept {
-    return __v.__value_ <= 0;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator> (weak_ordering __v, _CmpUnspecifiedParam) noexcept {
-    return __v.__value_ > 0;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(weak_ordering __v, _CmpUnspecifiedParam) noexcept {
-    return __v.__value_ >= 0;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator< (_CmpUnspecifiedParam, weak_ordering __v) noexcept {
-    return 0 < __v.__value_;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(_CmpUnspecifiedParam, weak_ordering __v) noexcept {
-    return 0 <= __v.__value_;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator> (_CmpUnspecifiedParam, weak_ordering __v) noexcept {
-    return 0 > __v.__value_;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(_CmpUnspecifiedParam, weak_ordering __v) noexcept {
-    return 0 >= __v.__value_;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr weak_ordering operator<=>(weak_ordering __v, _CmpUnspecifiedParam) noexcept {
-    return __v;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr weak_ordering operator<=>(_CmpUnspecifiedParam, weak_ordering __v) noexcept {
-    return __v < 0 ? weak_ordering::greater : (__v > 0 ? weak_ordering::less : __v);
-  }
-
-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);
-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 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
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(strong_ordering, strong_ordering) noexcept = default;
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(strong_ordering __v, _CmpUnspecifiedParam) noexcept {
-    return __v.__value_ == 0;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator< (strong_ordering __v, _CmpUnspecifiedParam) noexcept {
-    return __v.__value_ < 0;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(strong_ordering __v, _CmpUnspecifiedParam) noexcept {
-    return __v.__value_ <= 0;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator> (strong_ordering __v, _CmpUnspecifiedParam) noexcept {
-    return __v.__value_ > 0;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(strong_ordering __v, _CmpUnspecifiedParam) noexcept {
-    return __v.__value_ >= 0;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator< (_CmpUnspecifiedParam, strong_ordering __v) noexcept {
-    return 0 < __v.__value_;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(_CmpUnspecifiedParam, strong_ordering __v) noexcept {
-    return 0 <= __v.__value_;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator> (_CmpUnspecifiedParam, strong_ordering __v) noexcept {
-    return 0 > __v.__value_;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(_CmpUnspecifiedParam, strong_ordering __v) noexcept {
-    return 0 >= __v.__value_;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr strong_ordering operator<=>(strong_ordering __v, _CmpUnspecifiedParam) noexcept {
-    return __v;
-  }
-
-  _LIBCPP_INLINE_VISIBILITY friend constexpr strong_ordering operator<=>(_CmpUnspecifiedParam, strong_ordering __v) noexcept {
-    return __v < 0 ? strong_ordering::greater : (__v > 0 ? strong_ordering::less : __v);
-  }
-
-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);
-
-// named comparison functions
-_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,
-  _PartialOrd,
-  _WeakOrd,
-  _StrongOrd,
-  _CCC_Size
-};
-
-template <class _Tp>
-_LIBCPP_INLINE_VISIBILITY
-constexpr _ClassifyCompCategory __type_to_enum() noexcept {
-  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(const _ClassifyCompCategory (&__types)[_Size]) {
-  int __seen[_CCC_Size] = {};
-  for (auto __type : __types)
-    ++__seen[__type];
-  if (__seen[_None])
-    return _None;
-  if (__seen[_PartialOrd])
-    return _PartialOrd;
-  if (__seen[_WeakOrd])
-    return _WeakOrd;
-  return _StrongOrd;
-}
-
-template <class ..._Ts>
-constexpr auto __get_comp_type() {
-  using _CCC = _ClassifyCompCategory;
-  constexpr _CCC __type_kinds[] = {_StrongOrd, __type_to_enum<_Ts>()...};
-  constexpr _CCC _Cat = __compute_comp_type(__type_kinds);
-  if constexpr (_Cat == _None)
-    return void();
-  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);
 
 #endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR)
 
 _LIBCPP_END_NAMESPACE_STD
 
 #endif // _LIBCPP_COMPARE

libcxx/include/module.modulemap

module chrono {
     header "chrono"
     export *
   }
   module codecvt {
     header "codecvt"
     export *
   }
   module compare {
     header "compare"
     export *
+
+    module __compare {
+      module ordering                   { private header "__compare/ordering.h"                   }
+      module common_comparison_category { private header "__compare/common_comparison_category.h" }
+    }
   }
   module complex {
     header "complex"
     export *
   }
   module concepts {
     header "concepts"
     export *