[libcxx-commits] [libcxx] [libc++][chono] Use hidden friends for leap_second comparison. (PR #104713)

[Louis Dionne via libcxx-commits]

================
@@ -50,70 +50,75 @@ class leap_second {
 private:
   sys_seconds __date_;
   seconds __value_;
-};
 
-_LIBCPP_HIDE_FROM_ABI inline constexpr bool operator==(const leap_second& __x, const leap_second& __y) {
-  return __x.date() == __y.date();
-}
-
-_LIBCPP_HIDE_FROM_ABI inline constexpr strong_ordering operator<=>(const leap_second& __x, const leap_second& __y) {
-  return __x.date() <=> __y.date();
-}
-
-template <class _Duration>
-_LIBCPP_HIDE_FROM_ABI constexpr bool operator==(const leap_second& __x, const sys_time<_Duration>& __y) {
-  return __x.date() == __y;
-}
-
-template <class _Duration>
-_LIBCPP_HIDE_FROM_ABI constexpr bool operator<(const leap_second& __x, const sys_time<_Duration>& __y) {
-  return __x.date() < __y;
-}
-
-template <class _Duration>
-_LIBCPP_HIDE_FROM_ABI constexpr bool operator<(const sys_time<_Duration>& __x, const leap_second& __y) {
-  return __x < __y.date();
-}
-
-template <class _Duration>
-_LIBCPP_HIDE_FROM_ABI constexpr bool operator>(const leap_second& __x, const sys_time<_Duration>& __y) {
-  return __y < __x;
-}
-
-template <class _Duration>
-_LIBCPP_HIDE_FROM_ABI constexpr bool operator>(const sys_time<_Duration>& __x, const leap_second& __y) {
-  return __y < __x;
-}
-
-template <class _Duration>
-_LIBCPP_HIDE_FROM_ABI constexpr bool operator<=(const leap_second& __x, const sys_time<_Duration>& __y) {
-  return !(__y < __x);
-}
-
-template <class _Duration>
-_LIBCPP_HIDE_FROM_ABI constexpr bool operator<=(const sys_time<_Duration>& __x, const leap_second& __y) {
-  return !(__y < __x);
-}
-
-template <class _Duration>
-_LIBCPP_HIDE_FROM_ABI constexpr bool operator>=(const leap_second& __x, const sys_time<_Duration>& __y) {
-  return !(__x < __y);
-}
-
-template <class _Duration>
-_LIBCPP_HIDE_FROM_ABI constexpr bool operator>=(const sys_time<_Duration>& __x, const leap_second& __y) {
-  return !(__x < __y);
-}
-
-#    ifndef _LIBCPP_COMPILER_GCC
-// This requirement cause a compilation loop in GCC-13 and running out of memory.
-// TODO TZDB Test whether GCC-14 fixes this.
-template <class _Duration>
-  requires three_way_comparable_with<sys_seconds, sys_time<_Duration>>
-_LIBCPP_HIDE_FROM_ABI constexpr auto operator<=>(const leap_second& __x, const sys_time<_Duration>& __y) {
-  return __x.date() <=> __y;
-}
-#    endif
+  // The function
+  //   template<class Duration>
+  //    requires three_way_comparable_with<sys_seconds, sys_time<Duration>>
+  //    constexpr auto operator<=>(const leap_second& x, const sys_time<Duration>& y) noexcept;
+  //
+  // Has constraints that are recursive (LWG4139). The proposed resolution is
+  // to make the funcion a hidden friend. For consistency make this change for
+  // all comparison functions.
----------------
ldionne wrote:

```suggestion
  // has constraints that are recursive (LWG4139). The proposed resolution is
  // to make the function a hidden friend. For consistency, we do this for all
  // comparison functions.
```

https://github.com/llvm/llvm-project/pull/104713