Thu, 30 Jul 2009 10:29:53 +0100
6827648: Extremely slow compilation time for visitor pattern code + generics
Summary: Javac unnecessarily recomputates type-substitutions multiple times
Reviewed-by: jjg
1 /*
2 * Copyright 2002 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 */
24 /*
25 * @test
26 * @bug 4698375
27 * @summary generics: subtyping problem when type parameters permuted
28 * @author gafter
29 *
30 * @compile PermuteBound.java
31 */
33 package test.tools.javac.generics.PermuteBound;
35 class C<X, Y> {}
37 class D<X, Y> extends C<X, Y>
38 {
39 void f(C<X, Y> c)
40 {
41 D<X, Y> d = (D<X, Y>) c;// OK because D extends C
42 }
44 void g(C<Y, X> c)// parameters X and Y are now permuted
45 {
46 D<Y, X> d = (D<Y, X>) c;// should also be OK but is not !?
47 // ^
48 // inconvertible types
49 // found : C<Y,X>
50 // required : D<Y,X>
51 }
52 /*
53 void gWorkAround(C<Y, X> c)// but generates unchecked warning
54 {
55 D<Y, X> d = (D) ((C) c);
56 }
57 */
58 }