diff --git a/Source/cmLinkedTree.h b/Source/cmLinkedTree.h
index 721a24606..93d801e26 100644
--- a/Source/cmLinkedTree.h
+++ b/Source/cmLinkedTree.h
@@ -24,7 +24,7 @@
   needs of the cmState.  For example, the Truncate() method is a specific
   requirement of the cmState.
 
-  An empty cmLinkedTree provides a Root() method, and an Extend() method,
+  An empty cmLinkedTree provides a Root() method, and an Push() method,
   each of which return iterators.  A Tree can be built up by extending
   from the root, and then extending from any other iterator.
 
@@ -142,14 +142,14 @@ public:
     return iterator(const_cast<cmLinkedTree*>(this), 0);
   }
 
-  iterator Extend(iterator it)
+  iterator Push(iterator it)
   {
-    return Extend_impl(it, T());
+    return Push_impl(it, T());
   }
 
-  iterator Extend(iterator it, T t)
+  iterator Push(iterator it, T t)
   {
-    return Extend_impl(it, t);
+    return Push_impl(it, t);
   }
 
   iterator Truncate()
@@ -179,7 +179,7 @@ private:
     return &this->Data[pos];
   }
 
-  iterator Extend_impl(iterator it, T t)
+  iterator Push_impl(iterator it, T t)
   {
     assert(this->UpPositions.size() == this->Data.size());
     assert(it.Position <= this->UpPositions.size());
diff --git a/Source/cmState.cxx b/Source/cmState.cxx
index e20ac89fe..3c96d465d 100644
--- a/Source/cmState.cxx
+++ b/Source/cmState.cxx
@@ -288,7 +288,7 @@ cmState::Snapshot cmState::Reset()
   assert(pos->Policies.IsValid());
   assert(pos->PolicyRoot.IsValid());
   this->VarTree.Clear();
-  pos->Vars = this->VarTree.Extend(this->VarTree.Root());
+  pos->Vars = this->VarTree.Push(this->VarTree.Root());
   pos->Parent = this->VarTree.Root();
   pos->Root = this->VarTree.Root();
 
@@ -751,14 +751,14 @@ void cmState::Directory::ComputeRelativePathTopBinary()
 
 cmState::Snapshot cmState::CreateBaseSnapshot()
 {
-  PositionType pos = this->SnapshotData.Extend(this->SnapshotData.Root());
+  PositionType pos = this->SnapshotData.Push(this->SnapshotData.Root());
   pos->DirectoryParent = this->SnapshotData.Root();
   pos->ScopeParent = this->SnapshotData.Root();
   pos->SnapshotType = BaseType;
   pos->BuildSystemDirectory =
-      this->BuildsystemDirectory.Extend(this->BuildsystemDirectory.Root());
+      this->BuildsystemDirectory.Push(this->BuildsystemDirectory.Root());
   pos->ExecutionListFile =
-      this->ExecutionListFiles.Extend(this->ExecutionListFiles.Root());
+      this->ExecutionListFiles.Push(this->ExecutionListFiles.Root());
   pos->IncludeDirectoryPosition = 0;
   pos->CompileDefinitionsPosition = 0;
   pos->CompileOptionsPosition = 0;
@@ -768,7 +768,7 @@ cmState::Snapshot cmState::CreateBaseSnapshot()
   pos->PolicyScope = this->PolicyStack.Root();
   assert(pos->Policies.IsValid());
   assert(pos->PolicyRoot.IsValid());
-  pos->Vars = this->VarTree.Extend(this->VarTree.Root());
+  pos->Vars = this->VarTree.Push(this->VarTree.Root());
   assert(pos->Vars.IsValid());
   pos->Parent = this->VarTree.Root();
   pos->Root = this->VarTree.Root();
@@ -781,17 +781,17 @@ cmState::CreateBuildsystemDirectorySnapshot(Snapshot originSnapshot,
                                     long entryPointLine)
 {
   assert(originSnapshot.IsValid());
-  PositionType pos = this->SnapshotData.Extend(originSnapshot.Position);
+  PositionType pos = this->SnapshotData.Push(originSnapshot.Position);
   pos->EntryPointLine = entryPointLine;
   pos->EntryPointCommand = entryPointCommand;
   pos->DirectoryParent = originSnapshot.Position;
   pos->ScopeParent = originSnapshot.Position;
   pos->SnapshotType = BuildsystemDirectoryType;
   pos->BuildSystemDirectory =
-      this->BuildsystemDirectory.Extend(
+      this->BuildsystemDirectory.Push(
         originSnapshot.Position->BuildSystemDirectory);
   pos->ExecutionListFile =
-      this->ExecutionListFiles.Extend(
+      this->ExecutionListFiles.Push(
         originSnapshot.Position->ExecutionListFile);
   pos->BuildSystemDirectory->DirectoryEnd = pos;
   pos->Policies = originSnapshot.Position->Policies;
@@ -804,7 +804,7 @@ cmState::CreateBuildsystemDirectorySnapshot(Snapshot originSnapshot,
       originSnapshot.Position->Vars;
   pos->Parent = origin;
   pos->Root = origin;
-  pos->Vars = this->VarTree.Extend(origin);
+  pos->Vars = this->VarTree.Push(origin);
   cmState::Snapshot snapshot = cmState::Snapshot(this, pos);
   originSnapshot.Position->BuildSystemDirectory->Children.push_back(snapshot);
   return snapshot;
@@ -816,13 +816,13 @@ cmState::CreateFunctionCallSnapshot(cmState::Snapshot originSnapshot,
                                     long entryPointLine,
                                     std::string const& fileName)
 {
-  PositionType pos = this->SnapshotData.Extend(originSnapshot.Position,
-                                               *originSnapshot.Position);
+  PositionType pos = this->SnapshotData.Push(originSnapshot.Position,
+                                             *originSnapshot.Position);
   pos->ScopeParent = originSnapshot.Position;
   pos->EntryPointLine = entryPointLine;
   pos->EntryPointCommand = entryPointCommand;
   pos->SnapshotType = FunctionCallType;
-  pos->ExecutionListFile = this->ExecutionListFiles.Extend(
+  pos->ExecutionListFile = this->ExecutionListFiles.Push(
         originSnapshot.Position->ExecutionListFile, fileName);
   pos->BuildSystemDirectory->DirectoryEnd = pos;
   pos->PolicyScope = originSnapshot.Position->Policies;
@@ -830,7 +830,7 @@ cmState::CreateFunctionCallSnapshot(cmState::Snapshot originSnapshot,
   cmLinkedTree<cmDefinitions>::iterator origin =
       originSnapshot.Position->Vars;
   pos->Parent = origin;
-  pos->Vars = this->VarTree.Extend(origin);
+  pos->Vars = this->VarTree.Push(origin);
   return cmState::Snapshot(this, pos);
 }
 
@@ -841,12 +841,12 @@ cmState::CreateMacroCallSnapshot(cmState::Snapshot originSnapshot,
                                     long entryPointLine,
                                     std::string const& fileName)
 {
-  PositionType pos = this->SnapshotData.Extend(originSnapshot.Position,
-                                               *originSnapshot.Position);
+  PositionType pos = this->SnapshotData.Push(originSnapshot.Position,
+                                             *originSnapshot.Position);
   pos->EntryPointLine = entryPointLine;
   pos->EntryPointCommand = entryPointCommand;
   pos->SnapshotType = MacroCallType;
-  pos->ExecutionListFile = this->ExecutionListFiles.Extend(
+  pos->ExecutionListFile = this->ExecutionListFiles.Push(
         originSnapshot.Position->ExecutionListFile, fileName);
   assert(originSnapshot.Position->Vars.IsValid());
   pos->BuildSystemDirectory->DirectoryEnd = pos;
@@ -860,12 +860,12 @@ cmState::CreateCallStackSnapshot(cmState::Snapshot originSnapshot,
                                  long entryPointLine,
                                  const std::string& fileName)
 {
-  PositionType pos = this->SnapshotData.Extend(originSnapshot.Position,
-                                               *originSnapshot.Position);
+  PositionType pos = this->SnapshotData.Push(originSnapshot.Position,
+                                             *originSnapshot.Position);
   pos->EntryPointLine = entryPointLine;
   pos->EntryPointCommand = entryPointCommand;
   pos->SnapshotType = CallStackType;
-  pos->ExecutionListFile = this->ExecutionListFiles.Extend(
+  pos->ExecutionListFile = this->ExecutionListFiles.Push(
         originSnapshot.Position->ExecutionListFile, fileName);
   assert(originSnapshot.Position->Vars.IsValid());
   pos->BuildSystemDirectory->DirectoryEnd = pos;
@@ -878,8 +878,8 @@ cmState::CreateVariableScopeSnapshot(cmState::Snapshot originSnapshot,
                                      std::string const& entryPointCommand,
                                      long entryPointLine)
 {
-  PositionType pos = this->SnapshotData.Extend(originSnapshot.Position,
-                                               *originSnapshot.Position);
+  PositionType pos = this->SnapshotData.Push(originSnapshot.Position,
+                                             *originSnapshot.Position);
   pos->ScopeParent = originSnapshot.Position;
   pos->EntryPointLine = entryPointLine;
   pos->EntryPointCommand = entryPointCommand;
@@ -890,7 +890,7 @@ cmState::CreateVariableScopeSnapshot(cmState::Snapshot originSnapshot,
   cmLinkedTree<cmDefinitions>::iterator origin =
       originSnapshot.Position->Vars;
   pos->Parent = origin;
-  pos->Vars = this->VarTree.Extend(origin);
+  pos->Vars = this->VarTree.Push(origin);
   assert(pos->Vars.IsValid());
   return cmState::Snapshot(this, pos);
 }
@@ -901,12 +901,12 @@ cmState::CreateInlineListFileSnapshot(cmState::Snapshot originSnapshot,
                                       long entryPointLine,
                                       const std::string& fileName)
 {
-  PositionType pos = this->SnapshotData.Extend(originSnapshot.Position,
-                                               *originSnapshot.Position);
+  PositionType pos = this->SnapshotData.Push(originSnapshot.Position,
+                                             *originSnapshot.Position);
   pos->EntryPointLine = entryPointLine;
   pos->EntryPointCommand = entryPointCommand;
   pos->SnapshotType = InlineListFileType;
-  pos->ExecutionListFile = this->ExecutionListFiles.Extend(
+  pos->ExecutionListFile = this->ExecutionListFiles.Push(
         originSnapshot.Position->ExecutionListFile, fileName);
   pos->BuildSystemDirectory->DirectoryEnd = pos;
   pos->PolicyScope = originSnapshot.Position->Policies;
@@ -916,8 +916,8 @@ cmState::CreateInlineListFileSnapshot(cmState::Snapshot originSnapshot,
 cmState::Snapshot
 cmState::CreatePolicyScopeSnapshot(cmState::Snapshot originSnapshot)
 {
-  PositionType pos = this->SnapshotData.Extend(originSnapshot.Position,
-                                               *originSnapshot.Position);
+  PositionType pos = this->SnapshotData.Push(originSnapshot.Position,
+                                             *originSnapshot.Position);
   pos->SnapshotType = PolicyScopeType;
   pos->BuildSystemDirectory->DirectoryEnd = pos;
   pos->PolicyScope = originSnapshot.Position->Policies;
@@ -1113,8 +1113,8 @@ void cmState::Snapshot::PushPolicy(cmPolicies::PolicyMap entry, bool weak)
 {
   PositionType pos = this->Position;
   pos->Policies =
-      this->State->PolicyStack.Extend(pos->Policies,
-                                      PolicyStackEntry(entry, weak));
+    this->State->PolicyStack.Push(pos->Policies,
+                                  PolicyStackEntry(entry, weak));
 }
 
 bool cmState::Snapshot::PopPolicy()