From b526d8761895643cb42e62997240344420d65e0f Mon Sep 17 00:00:00 2001
From: Yuriy Chernyshov <georgthegreat@gmail.com>
Date: Tue, 8 Dec 2020 13:39:56 -0500
Subject: [PATCH] [libc++] Add std::hash<char8_t> specialization if char8_t is
 enabled

Differential Revision: https://reviews.llvm.org/D92325
---
 libcxx/include/functional |  1 +
 libcxx/include/utility    | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/libcxx/include/functional b/libcxx/include/functional
index 22c73c5790b..ffcff35f6e4 100644
--- a/libcxx/include/functional
+++ b/libcxx/include/functional
@@ -470,6 +470,7 @@ template <> struct hash<bool>;
 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>;
diff --git a/libcxx/include/utility b/libcxx/include/utility
index 2af552b4b34..6f27af70646 100644
--- a/libcxx/include/utility
+++ b/libcxx/include/utility
@@ -1364,6 +1364,16 @@ struct _LIBCPP_TEMPLATE_VIS hash<unsigned char>
     size_t operator()(unsigned char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
 };
 
+#ifndef _LIBCPP_NO_HAS_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 // !_LIBCPP_NO_HAS_CHAR8_T
+
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 
 template <>
-- 
2.11.0