[libcxx-commits] [libcxx] [libc++][chrono] P2592R3: Hashing for chrono (PR #165132)

[Nikolas Klauser via libcxx-commits]

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@@ -92,6 +93,17 @@ _LIBCPP_HIDE_FROM_ABI inline constexpr day& day::operator-=(const days& __dd) no
 
 } // namespace chrono
 
+#  if _LIBCPP_STD_VER >= 26
+
+template <>
+struct hash<chrono::day> {
+  _LIBCPP_HIDE_FROM_ABI static size_t operator()(const chrono::day& __d) noexcept {
+    return hash<unsigned>{}(static_cast<unsigned>(__d));
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philnik777 wrote:

I wonder whether it's worth going though `hash<unsigned>`. It's just the identity anyways.

https://github.com/llvm/llvm-project/pull/165132