Bug 842561. Assert that our inheritance chain is correct for WebIDL objects. r=peterv

We could drop the descriptor for Text if we changed nsIDocument::CreateTextNode
to return an already_AddRefed<Text>, but then we'd need more casting in
nsDocument.cpp for the XPCOM CreateTextNode.  Not sure which way is better,
really.

content/base/src/Makefile.in

@@ -51,6 +51,7 @@ EXPORTS_mozilla/dom = \
   DOMImplementation.h \
   EventSource.h \
   Link.h \
+  Text.h \
   $(NULL)
 
 CPPSRCS		= \
@@ -120,6 +121,7 @@ CPPSRCS		= \
 		nsStyledElement.cpp \
 		nsStyleLinkElement.cpp \
 		nsSyncLoadService.cpp \
+		Text.cpp \
 		nsTextFragment.cpp \
 		nsTextNode.cpp \
 		nsTraversal.cpp \

content/base/src/Text.cpp

@@ -0,0 +1,23 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/Text.h"
+
+namespace mozilla {
+namespace dom {
+
+already_AddRefed<Text>
+Text::SplitText(uint32_t aOffset, ErrorResult& rv)
+{
+  nsCOMPtr<nsIContent> newChild;
+  rv = SplitData(aOffset, getter_AddRefs(newChild));
+  if (rv.Failed()) {
+    return nullptr;
+  }
+  return static_cast<Text*>(newChild.forget().get());
+}
+
+} // namespace dom
+} // namespace mozilla

content/base/src/Text.h

@@ -0,0 +1,35 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_Text_h
+#define mozilla_dom_Text_h
+
+#include "nsGenericDOMDataNode.h"
+#include "mozilla/ErrorResult.h"
+
+namespace mozilla {
+namespace dom {
+
+class Text : public nsGenericDOMDataNode
+{
+public:
+  Text(already_AddRefed<nsINodeInfo> aNodeInfo)
+    : nsGenericDOMDataNode(aNodeInfo)
+  {}
+
+  using nsGenericDOMDataNode::GetWholeText;
+
+  // WebIDL API
+  already_AddRefed<Text> SplitText(uint32_t aOffset, ErrorResult& rv);
+  void GetWholeText(nsAString& aWholeText, ErrorResult& rv)
+  {
+    rv = GetWholeText(aWholeText);
+  }
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_Text_h

content/base/src/nsTextNode.cpp

@@ -185,17 +185,6 @@ void nsTextNode::UnbindFromTree(bool aDeep, bool aNullParent)
   nsGenericDOMDataNode::UnbindFromTree(aDeep, aNullParent);
 }
 
-already_AddRefed<nsTextNode>
-nsTextNode::SplitText(uint32_t aOffset, ErrorResult& rv)
-{
-  nsCOMPtr<nsIContent> newChild;
-  rv = SplitData(aOffset, getter_AddRefs(newChild));
-  if (rv.Failed()) {
-    return nullptr;
-  }
-  return static_cast<nsTextNode*>(newChild.forget().get());
-}
-
 #ifdef DEBUG
 void
 nsTextNode::List(FILE* out, int32_t aIndent) const

content/base/src/nsTextNode.h

@@ -10,19 +10,19 @@
  * Implementation of DOM Core's nsIDOMText node.
  */
 
-#include "nsGenericDOMDataNode.h"
+#include "mozilla/dom/Text.h"
 #include "nsIDOMText.h"
 #include "nsDebug.h"
 
 /**
  * Class used to implement DOM text nodes
  */
-class nsTextNode : public nsGenericDOMDataNode,
+class nsTextNode : public mozilla::dom::Text,
                    public nsIDOMText
 {
 public:
   nsTextNode(already_AddRefed<nsINodeInfo> aNodeInfo)
-    : nsGenericDOMDataNode(aNodeInfo)
+    : mozilla::dom::Text(aNodeInfo)
   {
     NS_ABORT_IF_FALSE(mNodeInfo->NodeType() == nsIDOMNode::TEXT_NODE,
                       "Bad NodeType in aNodeInfo");
@@ -62,14 +62,6 @@ public:
 
   virtual nsIDOMNode* AsDOMNode() { return this; }
 
-  // WebIDL API
-  already_AddRefed<nsTextNode> SplitText(uint32_t aOffset,
-                                         mozilla::ErrorResult& rv);
-  void GetWholeText(nsAString& aWholeText, mozilla::ErrorResult& rv)
-  {
-    rv = GetWholeText(aWholeText);
-  }
-
 #ifdef DEBUG
   virtual void List(FILE* out, int32_t aIndent) const;
   virtual void DumpContent(FILE* out, int32_t aIndent, bool aDumpAll) const;

content/xml/content/src/CDATASection.h

@@ -7,17 +7,17 @@
 #define mozilla_dom_CDATASection_h
 
 #include "nsIDOMCDATASection.h"
-#include "nsGenericDOMDataNode.h"
+#include "mozilla/dom/Text.h"
 
 namespace mozilla {
 namespace dom {
 
-class CDATASection : public nsGenericDOMDataNode,
+class CDATASection : public Text,
                      public nsIDOMCDATASection
 {
 public:
   CDATASection(already_AddRefed<nsINodeInfo> aNodeInfo)
-    : nsGenericDOMDataNode(aNodeInfo)
+    : Text(aNodeInfo)
   {
     NS_ABORT_IF_FALSE(mNodeInfo->NodeType() == nsIDOMNode::CDATA_SECTION_NODE,
                       "Bad NodeType in aNodeInfo");

dom/bindings/Bindings.conf

@@ -825,7 +825,9 @@ DOMInterfaces = {
 },
 
 'Text': {
-    'nativeType': 'nsTextNode',
+    # Total hack to allow binding code to realize that nsTextNode can
+    # in fact be cast to Text.
+    'headerFile': 'nsTextNode.h',
 },
 
 'TextDecoder': [

dom/bindings/Codegen.py

@@ -1819,6 +1819,18 @@ def InitUnforgeableProperties(descriptor, properties):
             "// finalizer trying to drop its ownership of the C++ object.\n"),
             post="\n")).define() if len(unforgeables) > 0 else ""
 
+def AssertInheritanceChain(descriptor):
+    asserts = ""
+    iface = descriptor.interface
+    while iface:
+        desc = descriptor.getDescriptor(iface.identifier.name)
+        asserts += (
+            "  MOZ_ASSERT(static_cast<%s*>(aObject) == \n"
+            "             reinterpret_cast<%s*>(aObject));\n" %
+            (desc.nativeType, desc.nativeType))
+        iface = iface.parent
+    return asserts
+
 class CGWrapWithCacheMethod(CGAbstractMethod):
     """
     Create a wrapper JSObject for a given native that implements nsWrapperCache.
@@ -1839,7 +1851,8 @@ class CGWrapWithCacheMethod(CGAbstractMethod):
             return """  *aTriedToWrap = true;
   return aObject->GetJSObject();"""
 
-        return """  *aTriedToWrap = true;
+        return """%s
+  *aTriedToWrap = true;
 
   JSObject* parent = WrapNativeParent(aCx, aScope, aObject->GetParentObject());
   if (!parent) {
@@ -1868,7 +1881,8 @@ class CGWrapWithCacheMethod(CGAbstractMethod):
 %s
   aCache->SetWrapper(obj);
 
-  return obj;""" % (CheckPref(self.descriptor, "global", "*aTriedToWrap", "NULL", "aCache"),
+  return obj;""" % (AssertInheritanceChain(self.descriptor),
+                    CheckPref(self.descriptor, "global", "*aTriedToWrap", "NULL", "aCache"),
                     CreateBindingJSObject(self.descriptor, "parent"),
                     InitUnforgeableProperties(self.descriptor, self.properties))
 
@@ -1899,7 +1913,7 @@ class CGWrapNonWrapperCacheMethod(CGAbstractMethod):
         self.properties = properties
 
     def definition_body(self):
-        return """
+        return """%s
   JSObject* global = JS_GetGlobalForObject(aCx, aScope);
   JSObject* proto = GetProtoObject(aCx, global);
   if (!proto) {
@@ -1908,7 +1922,8 @@ class CGWrapNonWrapperCacheMethod(CGAbstractMethod):
 
 %s
 %s
-  return obj;""" % (CreateBindingJSObject(self.descriptor, "global"),
+  return obj;""" % (AssertInheritanceChain(self.descriptor),
+                    CreateBindingJSObject(self.descriptor, "global"),
                     InitUnforgeableProperties(self.descriptor, self.properties))
 
 builtinNames = {