Name: gm110360 Date: 09/19/2002


FULL PRODUCT VERSION :
java version "1.4.1"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1-b21)
Java HotSpot(TM) Client VM (build 1.4.1-b21, mixed mode)


FULL OPERATING SYSTEM VERSION :
glibc-2.2.4-19.3
Linux quaffle 2.4.9-31smp #1 SMP Tue Feb 26 06:55:00 EST 2002 i686 unknown
/etc/redhat-release

A DESCRIPTION OF THE PROBLEM :
There was a regression between 1.4.1 release candidate (b19) and final version (b21) in accepting code
compiled by the jikes compiler. Jikes 1.16 emits <array>.clone() rather than Object.clone() in the
bytecode, in accordance with JLS 13.1 (javac still does not do this, but that is a subject for a different
bug report).

With earlier VMs, the sample program below worked, but now it causes a VerifyError.


This bug may require specification clarification, in both the JLS and the JVMS. See also my longer
description of this issue at http://groups.yahoo.com/group/java-spec-report/message/764.



REGRESSION. Last worked in version 1.4.1

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Compile the program below with jikes 1.16 or greater (jikes is obtainable from
http://www-124.ibm.com/developerworks/project/showfiles.php?group_id=10). Compilation with javac does not
show this bug - you need jikes (or else manually assembling a .class file to call invokevirtual
String[].clone()).

$ jikes Foo.java
$

2. Execute with the b19 or earlier builds
$ /opt/java/bin/java -version
java version "1.3.1_04"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.1_04-b02)
Java HotSpot(TM) Client VM (build 1.3.1_04-b02, mixed mode)
$ /opt/java/bin/java Foo
[Ljava.lang.String;@1fcc69
$

3. Try again with 1.4.1 final candidate.
$ java version
java version "1.4.1"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1-b21)
Java HotSpot(TM) Client VM (build 1.4.1-b21, mixed mode)
$ java Foo
Exception in thread "main" java.lang.IllegalAccessError: tried to access method
java.lang.Object.clone()Ljava/lang/Object; from class Foo
        at Foo.main(Foo.java:3)
$


EXPECTED VERSUS ACTUAL BEHAVIOR :
The program should always execute. However, the 1.4.1 final regression causes a VerifyError:


ERROR MESSAGES/STACK TRACES THAT OCCUR :
Exception in thread "main" java.lang.IllegalAccessError: tried to access method
java.lang.Object.clone()Ljava/lang/Object; from class Foo
        at Foo.main(Foo.java:3)


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
class Foo {
  public static void main(String[] args) {
    System.out.println(args.clone());
  }
}


---------- END SOURCE ----------

CUSTOMER WORKAROUND :
Jikes 1.16 cannot be used if the targetted VM is java 1.4.1-b21. A bug was raised against jikes
(http://www-124.ibm.com/developerworks/bugs/?func=detailbug&bug_id=3290&group_id=10), so future versions may
emit Object.clone() the way javac does currently, but I think this violates JLS 13.1.

Meanwhile, the user can revert to an older VM, or can do the following to avoid the VerifyError when
compiling with jikes 1.16:
class Foo {
  public static void main(String[] args) {
    Cloneable o = args;
    try {
      o.clone();
    } catch (CloneNotSupportedException e) {
      assert false : "Impossible - array clones always succeed";
    }
  }
}

Release Regression From : 1.4.1
The above release value was the last known release where this
bug was known to work. Since then there has been a regression.

(Review ID: 164758)
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