WTF: Support enums in DefaultHash and HashTraits by casting to integral types.

third_party/WebKit/Source/wtf/HashFunctions.h

 /*
  * Copyright (C) 2005, 2006, 2008 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 180 matching lines @@
     return a == b.get();
   }
 };
 
 // Default hash function for each type.
 template <typename T>
 struct DefaultHash;
 
 // Actual implementation of DefaultHash.
 //
-// The case of |isIntegral| == false is not implemented. If you see a compile
-// error saying DefaultHashImpl<T, false> is not defined, that's because the
-// default hash functions for T are not defined. You need to implement them
+// The case of |isIntegralOrEnum| == false is not implemented. If you see a
+// compile error saying DefaultHashImpl<T, false> is not defined, that's because
+// the default hash functions for T are not defined. You need to implement them
 // yourself.
-template <typename T, bool isIntegral>
+template <typename T, bool isIntegralOrEnum>
 struct DefaultHashImpl;
 
 template <typename T>
 struct DefaultHashImpl<T, true> {
-  using Hash = IntHash<typename std::make_unsigned<T>::type>;
+  using Hash = IntHash<T>;
 };
 
 // Canonical implementation of DefaultHash.
 template <typename T>
-struct DefaultHash : DefaultHashImpl<T, std::is_integral<T>::value> {};
+struct DefaultHash
+    : DefaultHashImpl<T, std::is_integral<T>::value || std::is_enum<T>::value> {
+};
 
 // Specializations of DefaultHash follow.
 template <>
 struct DefaultHash<float> {
   using Hash = FloatHash<float>;
 };
 template <>
 struct DefaultHash<double> {
   using Hash = FloatHash<double>;
 };
@@ skipping 56 matching lines @@
   using Hash = PairHash<T, U>;
 };
 
 }  // namespace WTF
 
 using WTF::DefaultHash;
 using WTF::IntHash;
 using WTF::PtrHash;
 
 #endif  // WTF_HashFunctions_h