4 files changed, 17 insertions, 4 deletions
diff --git a/include/llvm/Support/CommandLine.h b/include/llvm/Support/CommandLine.h
index c0bfbae037..4efb6a67cf 100644
--- a/include/llvm/Support/CommandLine.h
+++ b/include/llvm/Support/CommandLine.h
@@ -350,6 +350,9 @@ struct cat {
 struct GenericOptionValue {
   virtual ~GenericOptionValue() {}
   virtual bool compare(const GenericOptionValue &V) const = 0;
+
+private:
+  virtual void anchor();
 };
 
 template<class DataType> struct OptionValue;
@@ -1752,6 +1755,7 @@ void getRegisteredOptions(StringMap<Option*> &Map);
 /// \brief Saves strings in the inheritor's stable storage and returns a stable
 /// raw character pointer.
 class StringSaver {
+  virtual void anchor();
 public:
   virtual const char *SaveString(const char *Str) = 0;
   virtual ~StringSaver() {};  // Pacify -Wnon-virtual-dtor.
diff --git a/include/llvm/Support/ValueHandle.h b/include/llvm/Support/ValueHandle.h
index b49341c3ff..bc02ba31b9 100644
--- a/include/llvm/Support/ValueHandle.h
+++ b/include/llvm/Support/ValueHandle.h
@@ -339,6 +339,7 @@ public:
 /// rearrange itself when the pointer changes).  Unlike ValueHandleBase, this
 /// class has a vtable and a virtual destructor.
 class CallbackVH : public ValueHandleBase {
+  virtual void anchor();
 protected:
   CallbackVH(const CallbackVH &RHS)
     : ValueHandleBase(Callback, RHS) {}
@@ -365,13 +366,13 @@ public:
   ///
   /// All implementations must remove the reference from this object to the
   /// Value that's being destroyed.
-  virtual void deleted();
+  virtual void deleted() { setValPtr(NULL); }
 
   /// Called when this->getValPtr()->replaceAllUsesWith(new_value) is called,
   /// _before_ any of the uses have actually been replaced.  If WeakVH were
   /// implemented as a CallbackVH, it would use this method to call
   /// setValPtr(new_value).  AssertingVH would do nothing in this method.
-  virtual void allUsesReplacedWith(Value *);
+  virtual void allUsesReplacedWith(Value *) {}
 };
 
 } // End llvm namespace
diff --git a/include/llvm/Support/YAMLParser.h b/include/llvm/Support/YAMLParser.h
index 0e780bab12..702044936c 100644
--- a/include/llvm/Support/YAMLParser.h
+++ b/include/llvm/Support/YAMLParser.h
@@ -105,6 +105,7 @@ private:
 
 /// @brief Abstract base class for all Nodes.
 class Node {
+   virtual void anchor();
 public:
   enum NodeKind {
     NK_Null,
@@ -175,6 +176,7 @@ private:
 /// Example:
 ///   !!null null
 class NullNode : public Node {
+  virtual void anchor();
 public:
   NullNode(OwningPtr<Document> &D)
       : Node(NK_Null, D, StringRef(), StringRef()) {}
@@ -190,6 +192,7 @@ public:
 /// Example:
 ///   Adena
 class ScalarNode : public Node {
+  virtual void anchor();
 public:
   ScalarNode(OwningPtr<Document> &D, StringRef Anchor, StringRef Tag,
              StringRef Val)
@@ -231,6 +234,7 @@ private:
 /// Example:
 ///   Section: .text
 class KeyValueNode : public Node {
+  virtual void anchor();
 public:
   KeyValueNode(OwningPtr<Document> &D)
     : Node(NK_KeyValue, D, StringRef(), StringRef())
@@ -342,6 +346,7 @@ void skip(CollectionType &C) {
 ///   Name: _main
 ///   Scope: Global
 class MappingNode : public Node {
+  virtual void anchor();
 public:
   enum MappingType {
     MT_Block,
@@ -391,6 +396,7 @@ private:
 ///   - Hello
 ///   - World
 class SequenceNode : public Node {
+  virtual void anchor();
 public:
   enum SequenceType {
     ST_Block,
@@ -446,6 +452,7 @@ private:
 /// Example:
 ///   *AnchorName
 class AliasNode : public Node {
+  virtual void anchor();
 public:
   AliasNode(OwningPtr<Document> &D, StringRef Val)
     : Node(NK_Alias, D, StringRef(), StringRef()), Name(Val) {}
diff --git a/include/llvm/Support/YAMLTraits.h b/include/llvm/Support/YAMLTraits.h
index 8be54394de..c19eb23c5c 100644
--- a/include/llvm/Support/YAMLTraits.h
+++ b/include/llvm/Support/YAMLTraits.h
@@ -725,6 +725,7 @@ private:
   virtual bool canElideEmptySequence();
 
   class HNode {
+    virtual void anchor();
   public:
     HNode(Node *n) : _node(n) { }
     virtual ~HNode() { }
@@ -734,9 +735,9 @@ private:
   };
 
   class EmptyHNode : public HNode {
+    virtual void anchor();
   public:
     EmptyHNode(Node *n) : HNode(n) { }
-    virtual ~EmptyHNode() {}
     static inline bool classof(const HNode *n) {
       return NullNode::classof(n->_node);
     }
@@ -744,9 +745,9 @@ private:
   };
 
   class ScalarHNode : public HNode {
+    virtual void anchor();
   public:
     ScalarHNode(Node *n, StringRef s) : HNode(n), _value(s) { }
-    virtual ~ScalarHNode() { }
 
     StringRef value() const { return _value; }