diff -r 396b117c1743 -r 9d9d08922405 src/share/classes/com/sun/tools/javac/comp/Check.java
--- a/src/share/classes/com/sun/tools/javac/comp/Check.java	Wed Apr 14 12:23:29 2010 +0100
+++ b/src/share/classes/com/sun/tools/javac/comp/Check.java	Wed Apr 14 12:31:55 2010 +0100
@@ -640,6 +640,43 @@
             return true;
     }
 
+    /** Check that the type inferred using the diamond operator does not contain
+     *  non-denotable types such as captured types or intersection types.
+     *  @param t the type inferred using the diamond operator
+     */
+    List<Type> checkDiamond(ClassType t) {
+        DiamondTypeChecker dtc = new DiamondTypeChecker();
+        ListBuffer<Type> buf = ListBuffer.lb();
+        for (Type arg : t.getTypeArguments()) {
+            if (!dtc.visit(arg, null)) {
+                buf.append(arg);
+            }
+        }
+        return buf.toList();
+    }
+
+    static class DiamondTypeChecker extends Types.SimpleVisitor<Boolean, Void> {
+        public Boolean visitType(Type t, Void s) {
+            return true;
+        }
+        @Override
+        public Boolean visitClassType(ClassType t, Void s) {
+            if (t.isCompound()) {
+                return false;
+            }
+            for (Type targ : t.getTypeArguments()) {
+                if (!visit(targ, s)) {
+                    return false;
+                }
+            }
+            return true;
+        }
+        @Override
+        public Boolean visitCapturedType(CapturedType t, Void s) {
+            return false;
+        }
+    }
+
     /** Check that given modifiers are legal for given symbol and
      *  return modifiers together with any implicit modififiers for that symbol.
      *  Warning: we can't use flags() here since this method