Optimization of HashTraits<RefPtr<P> >::emptyValue()

Source/wtf/HashTraits.h

 /*
  * Copyright (C) 2005, 2006, 2007, 2008, 2011, 2012 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 120 matching lines @@
         typedef PassOwnPtr<P> PassOutType;
         static PassOwnPtr<P> passOut(OwnPtr<P>& value) { return value.release(); }
         static PassOwnPtr<P> passOut(std::nullptr_t) { return nullptr; }
 
         typedef typename OwnPtr<P>::PtrType PeekType;
         static PeekType peek(const OwnPtr<P>& value) { return value.get(); }
         static PeekType peek(std::nullptr_t) { return 0; }
     };
 
     template<typename P> struct HashTraits<RefPtr<P> > : SimpleClassHashTraits<RefPtr<P> > {
-        static RefPtr<P>& emptyValue()
-        {
-            static RefPtr<P>& null = *(new RefPtr<P>);
-            return null;
-        }
+        static P* emptyValue() { return 0; }
 
         typedef PassRefPtr<P> PassInType;
         static void store(PassRefPtr<P> value, RefPtr<P>& storage) { storage = value; }
 
         typedef PassRefPtr<P> PassOutType;
         static PassRefPtr<P> passOut(RefPtr<P>& value) { return value.release(); }
+        static PassRefPtr<P> passOut(P* value) { return value; }

[eseidel, 2013/05/06 18:38:59]

What does this do?  Is it safe?

+
         // FIXME: We should consider changing PeekType to a raw pointer for better performance,
         // but then callers won't need to call get; doing so will require updating many call sites.
     };
 
     template<> struct HashTraits<String> : SimpleClassHashTraits<String> {
         static const bool hasIsEmptyValueFunction = true;
         static bool isEmptyValue(const String&);
     };
 
     // This struct template is an implementation detail of the isHashTraitsEmptyValue function,
@@ skipping 84 matching lines @@
     };
 
 } // namespace WTF
 
 using WTF::HashTraits;
 using WTF::PairHashTraits;
 using WTF::NullableHashTraits;
 using WTF::SimpleClassHashTraits;
 
 #endif // WTF_HashTraits_h