[libc++][chrono] Entirely remove relational operators for std::chrono::weekday (llvm#122428)

Follows-up llvm#98730.

Author: frederick-vs-ja

libcxx/docs/ReleaseNotes/20.rst

@@ -117,9 +117,8 @@ Deprecations and Removals
   removed in language modes prior to C++20. If you are using these features prior to C++20, you will need to
   update to ``-std=c++20``.
 
-- TODO: The relational operators for ``std::chrono::weekday`` will be removed entirely, and the
-  ``_LIBCPP_ENABLE_REMOVED_WEEKDAY_RELATIONAL_OPERATORS`` macro that was used to re-enable this extension will be
-  ignored in LLVM 20.
+- The relational operators for ``std::chrono::weekday`` has been removed entirely, and the
+  ``_LIBCPP_ENABLE_REMOVED_WEEKDAY_RELATIONAL_OPERATORS`` macro is now ignored.
 
 - The ``_LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST`` macro no longer has any effect. ``std::allocator<const T>`` is not
   supported as an extension anymore, please migrate any code that uses e.g. ``std::vector<const T>`` to be

libcxx/include/__chrono/weekday.h

@@ -79,25 +79,6 @@ _LIBCPP_HIDE_FROM_ABI inline constexpr bool operator==(const weekday& __lhs, con
   return __lhs.c_encoding() == __rhs.c_encoding();
 }
 
-// TODO(LLVM 20): Remove the escape hatch
-#  ifdef _LIBCPP_ENABLE_REMOVED_WEEKDAY_RELATIONAL_OPERATORS
-_LIBCPP_HIDE_FROM_ABI inline constexpr bool operator<(const weekday& __lhs, const weekday& __rhs) noexcept {
-  return __lhs.c_encoding() < __rhs.c_encoding();
-}
-
-_LIBCPP_HIDE_FROM_ABI inline constexpr bool operator>(const weekday& __lhs, const weekday& __rhs) noexcept {
-  return __rhs < __lhs;
-}
-
-_LIBCPP_HIDE_FROM_ABI inline constexpr bool operator<=(const weekday& __lhs, const weekday& __rhs) noexcept {
-  return !(__rhs < __lhs);
-}
-
-_LIBCPP_HIDE_FROM_ABI inline constexpr bool operator>=(const weekday& __lhs, const weekday& __rhs) noexcept {
-  return !(__lhs < __rhs);
-}
-#  endif // _LIBCPP_ENABLE_REMOVED_WEEKDAY_RELATIONAL_OPERATORS
-
 _LIBCPP_HIDE_FROM_ABI inline constexpr weekday operator+(const weekday& __lhs, const days& __rhs) noexcept {
   auto const __mu = static_cast<long long>(__lhs.c_encoding()) + __rhs.count();
   auto const __yr = (__mu >= 0 ? __mu : __mu - 6) / 7;

libcxx/include/__cxx03/__chrono/weekday.h

@@ -79,25 +79,6 @@ _LIBCPP_HIDE_FROM_ABI inline constexpr bool operator==(const weekday& __lhs, con
   return __lhs.c_encoding() == __rhs.c_encoding();
 }
 
-// TODO(LLVM 20): Remove the escape hatch
-#  ifdef _LIBCPP_ENABLE_REMOVED_WEEKDAY_RELATIONAL_OPERATORS
-_LIBCPP_HIDE_FROM_ABI inline constexpr bool operator<(const weekday& __lhs, const weekday& __rhs) noexcept {
-  return __lhs.c_encoding() < __rhs.c_encoding();
-}
-
-_LIBCPP_HIDE_FROM_ABI inline constexpr bool operator>(const weekday& __lhs, const weekday& __rhs) noexcept {
-  return __rhs < __lhs;
-}
-
-_LIBCPP_HIDE_FROM_ABI inline constexpr bool operator<=(const weekday& __lhs, const weekday& __rhs) noexcept {
-  return !(__rhs < __lhs);
-}
-
-_LIBCPP_HIDE_FROM_ABI inline constexpr bool operator>=(const weekday& __lhs, const weekday& __rhs) noexcept {
-  return !(__lhs < __rhs);
-}
-#  endif // _LIBCPP_ENABLE_REMOVED_WEEKDAY_RELATIONAL_OPERATORS
-
 _LIBCPP_HIDE_FROM_ABI inline constexpr weekday operator+(const weekday& __lhs, const days& __rhs) noexcept {
   auto const __mu = static_cast<long long>(__lhs.c_encoding()) + __rhs.count();
   auto const __yr = (__mu >= 0 ? __mu : __mu - 6) / 7;