[libcxx-commits] [PATCH] D92325: Add std::hash<char8_t> specialization if char8_t is enabled

[Yuriy Chernyshov via Phabricator via libcxx-commits]

georgthegreat created this revision.
Herald added a project: libc++.
Herald added a subscriber: libcxx-commits.
Herald added a reviewer: libc++.
georgthegreat requested review of this revision.

This diff is related to D92212 <https://reviews.llvm.org/D92212/> as it is not clear which macro should be tested to enabled char8_t support.

I hope @ldionne will make a decision.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D92325

Files:
  libcxx/include/functional
  libcxx/include/utility
  libcxx/test/libcxx/extensions/hash/specializations.pass.cpp


Index: libcxx/test/libcxx/extensions/hash/specializations.pass.cpp
===================================================================
--- libcxx/test/libcxx/extensions/hash/specializations.pass.cpp
+++ libcxx/test/libcxx/extensions/hash/specializations.pass.cpp
@@ -23,6 +23,9 @@
     assert(__gnu_cxx::hash<char>()(42) == 42);
     assert(__gnu_cxx::hash<signed char>()(42) == 42);
     assert(__gnu_cxx::hash<unsigned char>()(42) == 42);
+    #ifdef __cpp_lib_char8_t
+    assert(__gnu_cxx::hash<char8_t>()(42) == 42);
+    #endif
     assert(__gnu_cxx::hash<short>()(42) == 42);
     assert(__gnu_cxx::hash<unsigned short>()(42) == 42);
     assert(__gnu_cxx::hash<int>()(42) == 42);
Index: libcxx/include/utility
===================================================================
--- libcxx/include/utility
+++ libcxx/include/utility
@@ -1364,6 +1364,16 @@
     size_t operator()(unsigned char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
 };

+#ifdef __cpp_char8_t
+template <>
+struct _LIBCPP_TEMPLATE_VIS hash<char8_t>
+    : public unary_function<char8_t, size_t>
+{
+    _LIBCPP_INLINE_VISIBILITY
+    size_t operator()(char8_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
+};
+#endif // __cpp_char8_t
+
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS

 template <>
Index: libcxx/include/functional
===================================================================
--- libcxx/include/functional
+++ libcxx/include/functional
@@ -470,6 +470,7 @@
 template <> struct hash<char>;
 template <> struct hash<signed char>;
 template <> struct hash<unsigned char>;
+template <> struct hash<char8_t>; // since C++20
 template <> struct hash<char16_t>;
 template <> struct hash<char32_t>;
 template <> struct hash<wchar_t>;


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