--- a/langtools/src/share/classes/com/sun/tools/javac/comp/Attr.java	Fri May 30 10:42:43 2008 +0100
+++ b/langtools/src/share/classes/com/sun/tools/javac/comp/Attr.java	Fri May 30 11:08:40 2008 +0100
@@ -454,6 +454,8 @@
     void attribTypeVariables(List<JCTypeParameter> typarams, Env<AttrContext> env) {
         for (JCTypeParameter tvar : typarams) {
             TypeVar a = (TypeVar)tvar.type;
+            a.tsym.flags_field |= UNATTRIBUTED;
+            a.bound = Type.noType;
             if (!tvar.bounds.isEmpty()) {
                 List<Type> bounds = List.of(attribType(tvar.bounds.head, env));
                 for (JCExpression bound : tvar.bounds.tail)
@@ -464,13 +466,14 @@
                 // java.lang.Object.
                 types.setBounds(a, List.of(syms.objectType));
             }
+            a.tsym.flags_field &= ~UNATTRIBUTED;
         }
-    }
-
-    void attribBounds(List<JCTypeParameter> typarams, Env<AttrContext> env) {
         for (JCTypeParameter tvar : typarams)
             chk.checkNonCyclic(tvar.pos(), (TypeVar)tvar.type);
         attribStats(typarams, env);
+    }
+
+    void attribBounds(List<JCTypeParameter> typarams) {
         for (JCTypeParameter typaram : typarams) {
             Type bound = typaram.type.getUpperBound();
             if (bound != null && bound.tsym instanceof ClassSymbol) {
@@ -581,7 +584,7 @@
         try {
             chk.checkDeprecatedAnnotation(tree.pos(), m);
 
-            attribBounds(tree.typarams, env);
+            attribBounds(tree.typarams);
 
             // If we override any other methods, check that we do so properly.
             // JLS ???
@@ -2689,7 +2692,7 @@
         chk.validateAnnotations(tree.mods.annotations, c);
 
         // Validate type parameters, supertype and interfaces.
-        attribBounds(tree.typarams, env);
+        attribBounds(tree.typarams);
         chk.validateTypeParams(tree.typarams);
         chk.validate(tree.extending);
         chk.validate(tree.implementing);

--- a/langtools/src/share/classes/com/sun/tools/javac/comp/Check.java	Fri May 30 10:42:43 2008 +0100
+++ b/langtools/src/share/classes/com/sun/tools/javac/comp/Check.java	Fri May 30 11:08:40 2008 +0100
@@ -1486,6 +1486,8 @@
 
     private void checkNonCyclic1(DiagnosticPosition pos, Type t, Set<TypeVar> seen) {
         final TypeVar tv;
+        if  (t.tag == TYPEVAR && (t.tsym.flags() & UNATTRIBUTED) != 0)
+            return;
         if (seen.contains(t)) {
             tv = (TypeVar)t;
             tv.bound = new ErrorType();

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/generics/6677785/T6677785.java	Fri May 30 11:08:40 2008 +0100
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2008 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     6677785
+ * @summary REGRESSION: StackOverFlowError with Cyclic Class level Type Parameters when used in constructors
+ * @author Maurizio Cimadamore
+ * @compile/fail/ref=T6677785.out -XDstdout -XDrawDiagnostics T6677785.java
+ */
+public class T6677785<E extends T, T extends E> {
+     T6677785() {}
+     T6677785(E e) {}
+     T6677785(E e, T t) {}
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/generics/6677785/T6677785.out	Fri May 30 11:08:40 2008 +0100
@@ -0,0 +1,2 @@
+T6677785.java:31:23: compiler.err.cyclic.inheritance: E
+1 error