--- a/src/share/classes/com/sun/source/util/TreePath.java	Tue Jan 05 15:24:18 2010 -0800
+++ b/src/share/classes/com/sun/source/util/TreePath.java	Wed Jan 06 13:15:14 2010 -0800
@@ -120,19 +120,20 @@
     public Iterator<Tree> iterator() {
         return new Iterator<Tree>() {
             public boolean hasNext() {
-                return curr.parent != null;
+                return next != null;
             }
 
             public Tree next() {
-                curr = curr.parent;
-                return curr.leaf;
+                Tree t = next.leaf;
+                next = next.parent;
+                return t;
             }
 
             public void remove() {
                 throw new UnsupportedOperationException();
             }
 
-            private TreePath curr;
+            private TreePath next = TreePath.this;
         };
     }
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/tools/javac/T6855236.java	Wed Jan 06 13:15:14 2010 -0800
@@ -0,0 +1,95 @@
+/*
+ * Copyright 2010 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+ * @test
+ * @bug 6855236
+ * @summary Compiler Tree API TreePath class generates NullPointerException from Iterator
+ * @compile T6855236.java
+ * @compile -processor T6855236 -proc:only T6855236.java
+ */
+
+import java.util.*;
+
+import javax.annotation.processing.*;
+import javax.lang.model.*;
+import javax.lang.model.element.*;
+
+import com.sun.source.tree.*;
+import com.sun.source.util.*;
+
+@SupportedSourceVersion(SourceVersion.RELEASE_6)
+@SupportedAnnotationTypes("*")
+public class T6855236 extends AbstractProcessor {
+
+    private Trees trees;
+
+    @Override
+    public void init(ProcessingEnvironment pe) {
+        super.init(pe);
+        trees = Trees.instance(pe);
+    }
+
+    @Override
+    public boolean process(Set<? extends TypeElement> arg0, RoundEnvironment roundEnvironment) {
+        // Scanner class to scan through various component elements
+        CodeVisitor visitor = new CodeVisitor();
+
+        for (Element e : roundEnvironment.getRootElements()) {
+            TreePath tp = trees.getPath(e);
+            visitor.scan(tp, trees);
+        }
+
+        return true;
+    }
+
+    class CodeVisitor extends TreePathScanner<Object, Trees> {
+
+        @Override
+        public Object visitMethodInvocation(MethodInvocationTree node, Trees p) {
+            System.out.print("current path: ");
+            for (Tree t : getCurrentPath()) {
+                System.out.print('/');
+                System.out.print(t);
+           }
+            System.out.println();
+            System.out.println("parent path: " + getCurrentPath().getParentPath());
+            System.out.println("method select: " + node.getMethodSelect().toString());
+            for (ExpressionTree arg : node.getArguments()) {
+                System.out.println("argument: " + arg.toString());
+            }
+            return super.visitMethodInvocation(node, p);
+        }
+
+        @Override
+        public Object visitExpressionStatement(ExpressionStatementTree node, Trees p) {
+            ExpressionTree t = node.getExpression();
+            System.out.println("expression statement: " + t.toString());
+            return super.visitExpressionStatement(node, p);
+        }
+
+    }
+
+}
+
+