1 /*
 2  * Copyright (c) 2020, 2021, Oracle and/or its affiliates. All rights reserved.
 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 4  *
 5  * This code is free software; you can redistribute it and/or modify it
 6  * under the terms of the GNU General Public License version 2 only, as
 7  * published by the Free Software Foundation.
 8  *
 9  * This code is distributed in the hope that it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  * version 2 for more details (a copy is included in the LICENSE file that
13  * accompanied this code).
14  *
15  * You should have received a copy of the GNU General Public License version
16  * 2 along with this work; if not, write to the Free Software Foundation,
17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18  *
19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20  * or visit www.oracle.com if you need additional information or have any
21  * questions.
22  */
23 
24 /*
25  * @test
26  * @summary Test that a hidden class can be cast to its parent.
27  * DESCRIPTION
28  *     Try to cast an object of a hidden class to its parent (called CastToParentTest)
29  *         - (CastToParentTest) o
30  *         - o.getClass().cast(<hiddenClassObj>);
31  *     and cast to its grandparent (java.lang.Object).
32  *
33  * @library /test/lib
34  * @modules jdk.compiler
35  * @run main CastToParentTest
36  */
37 
38 import java.lang.invoke.MethodType;
39 import java.lang.invoke.MethodHandles;
40 import java.lang.invoke.MethodHandles.Lookup;
41 import static java.lang.invoke.MethodHandles.Lookup.ClassOption.*;
42 import jdk.test.lib.compiler.InMemoryJavaCompiler;
43 
44 public class CastToParentTest {
45 
46     static byte klassbuf[] = InMemoryJavaCompiler.compile("TestClass",
47         "public class TestClass extends CastToParentTest { " +
48         "    public static void concat(String one, String two) throws Throwable { " +
49         "        System.out.println(one + two);" +
50         " } } ");
51 
52     public static void main(String[] args) throws Throwable {
53         Lookup lookup = MethodHandles.lookup();
54         Class<?> c = lookup.defineHiddenClass(klassbuf, false, NESTMATE).lookupClass();
55         Object hiddenClassObj = c.newInstance();
56 
57         // Cast hidden class to its parent.
58         CastToParentTest parentObj = (CastToParentTest)hiddenClassObj;
59 
60         if (!parentObj.equals(hiddenClassObj)) {
61             throw new RuntimeException("Hidden class object cannot be cast to parent");
62         }
63 
64         // Try to cast using a different mechanism.
65         new CastToParentTest().getClass().cast(hiddenClassObj);
66 
67 
68         // Cast hidden class to its grandparent.
69         java.lang.Object grandparentObj = (java.lang.Object)hiddenClassObj;
70 
71         if (!grandparentObj.equals(hiddenClassObj)) {
72             throw new RuntimeException("Hidden class object cannot be cast to grandparent");
73         }
74 
75         // Try to cast using a different mechanism.
76         new java.lang.Object() {}.getClass().getSuperclass().cast(hiddenClassObj);
77     }
78 
79 }