--- a/nashorn/src/jdk/nashorn/internal/objects/NativeArguments.java	Wed Jun 19 21:07:59 2013 +0530
+++ b/nashorn/src/jdk/nashorn/internal/objects/NativeArguments.java	Thu Jun 20 13:45:38 2013 +0530
@@ -125,7 +125,7 @@
     @Override
     public void setArgument(final int key, final Object value) {
         if (namedArgs.has(key)) {
-            namedArgs.set(key, value, false);
+            namedArgs = namedArgs.set(key, value, false);
         }
     }
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nashorn/test/script/basic/JDK-8017046.js	Thu Jun 20 13:45:38 2013 +0530
@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2010, 2013, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * JDK-8017046: Cannot assign undefined to a function argument if the function uses arguments object
+ *
+ * @test
+ * @run
+ */
+
+function assert(value, msg) {
+    if (! value) {
+        fail(msg);
+    }
+}
+
+function func(a) {
+    assert(a === arguments[0], "a !== arguments[0]");
+    assert(a === "hello", "a !== 'hello'");
+    a = undefined;
+    assert(a === arguments[0], "a !== arguments[0]");
+    assert(a === undefined, "a !== undefined");
+    assert(typeof(a) === 'undefined', "typeof(a) is not 'undefined'");
+}
+
+func("hello");