[libcxx-commits] [libcxx] [libc++] Add missing C++20 [time.point.arithmetic] (PR #143165)

[Hristo Hristov via libcxx-commits]

================
@@ -58,6 +58,19 @@ class time_point {
 
   // arithmetic
 
+#if _LIBCPP_STD_VER >= 20
+  _LIBCPP_HIDE_FROM_ABI constexpr time_point& operator++() {
+    ++__d_;
+    return *this;
+  }
+  _LIBCPP_HIDE_FROM_ABI constexpr time_point operator++(int) { return time_point(__d_++); }
+  _LIBCPP_HIDE_FROM_ABI constexpr time_point& operator--() {
+    --__d_;
+    return *this;
+  }
+  _LIBCPP_HIDE_FROM_ABI constexpr time_point operator--(int) { return time_point(__d_--); }
----------------
Zingam wrote:

```suggestion
  _LIBCPP_HIDE_FROM_ABI constexpr time_point operator--(int) { return time_point{__d_--}; }
```
See https://eel.is/c++draft/time.point#arithmetic-6

https://github.com/llvm/llvm-project/pull/143165