[not for commit]

Source/heap/Visitor.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 34 matching lines @@
 
 #ifndef NDEBUG
 #define DEBUG_ONLY(x) x
 #else
 #define DEBUG_ONLY(x)
 #endif
 
 namespace WebCore {
 
 class FinalizedHeapObjectHeader;
+template<typename T> class GarbageCollected;
 template<typename T> class GarbageCollectedFinalized;
 class HeapObjectHeader;
 template<typename T> class Member;
 template<typename T> class WeakMember;
 class Visitor;
 
 template<bool needsTracing, bool isWeak, bool markWeakMembersStrongly, typename T, typename Traits> struct CollectionBackingTraceTrait;
 
 typedef void (*FinalizationCallback)(void*);
 typedef void (*VisitorCallback)(Visitor*, void* self);
@@ skipping 20 matching lines @@
 // inherits from GarbageCollected or GarbageCollectedFinalized.
 struct GCInfo {
     bool hasFinalizer() const { return m_nonTrivialFinalizer; }
     const char* m_typeMarker;
     TraceCallback m_trace;
     FinalizationCallback m_finalize;
     bool m_nonTrivialFinalizer;
 };
 
 // Template struct to detect whether type T inherits from
+// GarbageCollected.
+template<typename T>
+struct IsGarbageCollected {

[Mads Ager (chromium), 2014/02/18 06:50:50]

Can we use WTF::IsSubclassOfTemplate here?

WTF::IsSubclassOfTemplate<T, GarbageCollected>::value

[Vyacheslav Egorov (Chromium), 2014/02/18 09:37:44]

Done.

+    typedef char TrueType;
+    struct FalseType {
+        char dummy[2];
+    };
+    template<typename U> static TrueType has(GarbageCollected<U>*);
+    static FalseType has(...);
+    static bool const value = sizeof(has(static_cast<T*>(0))) == sizeof(TrueType);
+};
+
+
+// Template struct to detect whether type T inherits from
 // GarbageCollectedFinalized.
 template<typename T>
 struct IsGarbageCollectedFinalized {

[Mads Ager (chromium), 2014/02/18 06:50:50]

I think we can get rid of this one as well and use the WTF version?

     typedef char TrueType;
     struct FalseType {
         char dummy[2];
     };
     template<typename U> static TrueType has(GarbageCollectedFinalized<U>*);
     static FalseType has(...);
     static bool const value = sizeof(has(static_cast<T*>(0))) == sizeof(TrueType);
 };
 
 // The FinalizerTraitImpl specifies how to finalize objects. Object
@@ skipping 433 matching lines @@
     return visitor->isMarked(obj);
 }
 template<typename T> bool ObjectAliveTrait<Member<T> >::isAlive(Visitor* visitor, const Member<T>& obj)
 {
     return visitor->isMarked(obj.get());
 }
 
 }
 
 #endif