Disallow off-heap containers containing raw on-heap pointers.

third_party/WebKit/Source/wtf/ListHashSet.h

 /*
  * Copyright (C) 2005, 2006, 2007, 2008, 2011, 2012 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2011, Benjamin Poulain <ikipou@gmail.com>
  *
  * 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.
  *
@@ skipping 715 matching lines @@
   template <typename T, typename U>
   static bool equal(const T& a, const U& b) {
     return HashFunctions::equal(a->m_value, b);
   }
   template <typename T, typename U, typename V>
   static void translate(T*& location, U&& key, const V& allocator) {
     location = new (const_cast<V*>(&allocator)) T(std::forward<U>(key));
   }
 };
 
-template <typename T, size_t inlineCapacity, typename U, typename V>
-inline ListHashSet<T, inlineCapacity, U, V>::ListHashSet()
-    : m_head(nullptr), m_tail(nullptr) {}
+template <typename T, size_t inlineCapacity, typename U, typename Allocator>
+inline ListHashSet<T, inlineCapacity, U, Allocator>::ListHashSet()
+    : m_head(nullptr), m_tail(nullptr) {
+  static_assert(
+      Allocator::isGarbageCollected ||
+          !IsPointerToGarbageCollectedType<T>::value,
+      "Cannot put raw pointers to garbage-collected classes into "
+      "an off-heap ListHashSet. Use HeapListHashSet<Member<T>> instead.");
+}
 
 template <typename T, size_t inlineCapacity, typename U, typename V>
 inline ListHashSet<T, inlineCapacity, U, V>::ListHashSet(
     const ListHashSet& other)
     : m_head(nullptr), m_tail(nullptr) {
   const_iterator end = other.end();
   for (const_iterator it = other.begin(); it != end; ++it)
     add(*it);
 }
 
@@ skipping 352 matching lines @@
   // through the HashTable. That includes m_head and m_tail so we do not have
   // to explicitly trace them here.
   m_impl.trace(visitor);
 }
 
 }  // namespace WTF
 
 using WTF::ListHashSet;
 
 #endif  // WTF_ListHashSet_h