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

[A. Jiang via libcxx-commits]

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@@ -92,6 +94,15 @@ _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 static_cast<unsigned>(__d); }
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frederick-vs-ja wrote:

Per some recent decisions, we should add `[[nodiscard]]` to all new `hash::operator()`s. And then add test cases to `‎libcxx/test/libcxx/time/time.hash/nodiscard.verify.cpp`.

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