[DO NOT LAND] Example snippet for crbug.com/729447.

third_party/WebKit/Source/core/style/StyleTransformData.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 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,
@@ skipping 43 matching lines @@
          DataEquivalent<TransformOperation>(rotate_, o.rotate_) &&
          DataEquivalent<TransformOperation>(scale_, o.scale_);
 }
 
 bool StyleTransformData::Has3DTransform() const {
   return operations_.Has3DOperation() || (translate_ && translate_->Z() != 0) ||
          (rotate_ && (rotate_->X() != 0 || rotate_->Y() != 0)) ||
          (scale_ && scale_->Z() != 1);
 }
 
+// Simple GC'd class
+struct Cat : public GarbageCollected<Cat> {  // (A)
+  DECLARE_TRACE();
+};
+
+// Simple class that uses a GC'd class.
+template <class T>
+struct Ptr {
+  T* ptr;
+};
+
+// Simple overloaded template functions
+template <class T>
+void meow(const T*) {}
+
+template <class T>
+void meow(const Ptr<T>&) {}
+
+// Calls meow with explicit template parameters.
+// Expect to call meow(const T*).
+// error: [blink-gc] Class 'Ptr<blink::Cat>' contains invalid fields.
+void boom() {
+  meow<Cat>(new Cat);  // (B)
+}
+
 }  // namespace blink