6500701: Enhanced for loop with generics generates faulty bytecode

Lower is too strict when translating enhanced causing CCE to be thrown at runtime

Reviewed-by: jjg

langtools/src/share/classes/com/sun/tools/javac/comp/Lower.java

@@ -2944,8 +2944,10 @@ public class Lower extends TreeTranslator {
                                        itvar.type,
                                        List.<Type>nil());
             JCExpression vardefinit = make.App(make.Select(make.Ident(itvar), next));
-            if (iteratorTarget != syms.objectType)
+            if (tree.var.type.isPrimitive())
-                vardefinit = make.TypeCast(iteratorTarget, vardefinit);
+                vardefinit = make.TypeCast(types.upperBound(iteratorTarget), vardefinit);
+            else
+                vardefinit = make.TypeCast(tree.var.type, vardefinit);
             JCVariableDecl indexDef = (JCVariableDecl)make.VarDef(tree.var.mods,
                                                   tree.var.name,
                                                   tree.var.vartype,

langtools/test/tools/javac/foreach/T6500701.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2003 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 6500701
+ * @summary Enhanced for loop with generics generates faulty bytecode
+ * @author Maurizio Cimadamore
+ *
+ */
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class T6500701 {
+
+    private static void test() {
+        List list = new ArrayList();
+        list.add("");
+        List<Integer> aList = new ArrayList<Integer>();
+        aList.addAll(list);
+        for (Object a : aList) {
+            System.out.println(a);
+        }
+    }
+
+    public static void main(String[] args) {
+        test();
+    }
+}