diff -r 000000000000 -r 959103a6100f test/tools/javac/T6942649.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/tools/javac/T6942649.java	Wed Apr 27 01:34:52 2016 +0800
@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2010, 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.
+ */
+
+
+/*
+ * @test
+ * @bug 6942649
+ * @summary add hidden option to identify location and version of javac classes
+ */
+
+import java.io.*;
+
+public class T6942649 {
+    public static void main(String... args) throws Exception {
+        new T6942649().run();
+    }
+
+    void run() throws Exception {
+        test("-XDshowClass", "com.sun.tools.javac.Main");
+        test("-XDshowClass=com.sun.tools.javac.util.Log", "com.sun.tools.javac.util.Log");
+    }
+
+    void test(String opt, String clazz) throws Exception {
+        System.err.println("test " + opt);
+        StringWriter sw = new StringWriter();
+        PrintWriter pw = new PrintWriter(sw);
+        int rc = com.sun.tools.javac.Main.compile(new String[] { opt }, pw);
+        pw.close();
+        String out = sw.toString();
+        System.err.println("javac rc=" + rc + "\n" + out);
+        if (!out.contains(clazz))
+            throw new Exception("class name not found in output");
+        int lastDot = clazz.lastIndexOf(".");
+        if (!out.contains(clazz.substring(lastDot + 1) + ".class"))
+            throw new Exception("location of class not found in output");
+        if (!out.contains("MD5 checksum: "))
+            throw new Exception("checksum not found in output");
+    }
+}