a few months ago, Vesa Kaihlavirta wrote you about a problem with Kaffe and Jython (in both the CVS and 1.0.7 versions). Unfortunately, nobody was able to work out what the bug really was. It still exists in the current CVS version (updated today). Fortunately, I think I may have succeeded in making it shallow.
Vesa's original mail is at:
http://www.kaffe.org/pipermail/kaffe/2002-September/008910.html
It seems that the bug is with kaffe's handling of reflected virtual methods. The following code:
import java.lang.reflect.Method;
interface KaffeBugInterface {
void sayHi();
}
public class KaffeBug implements KaffeBugInterface {
public void sayHi() {
System.out.println("Hi");
}
public static void main(String[] argv) throws Exception {
KaffeBug kb = new KaffeBug();
kb.sayHi();
Method m = KaffeBugInterface.class.getMethod("sayHi",
new Class[0]);
m.invoke(kb, new Object[0]);
}
}
gives the expected output on IBM's Java 1.3.1,
benja@joy:~/gzz/bug$ /home/benja/IBMJava2-131/bin/java KaffeBug
Hi
Hi
but fails with Kaffe:
benja@joy:~/gzz/bug$ /usr/local/kaffe/bin/kaffe KaffeBug
Hi
java.lang.reflect.InvocationTargetException:
java.lang.CloneNotSupportedException: KaffeBug
at java.lang.Object.clone(Object.java:native)
at java.lang.reflect.Method.invoke0(Method.java:native)
at java.lang.reflect.Method.invoke(Method.java:256)
at KaffeBug.main(KaffeBug.java:18)
It seems like Kaffe calls the wrong method in cases like this, here 'clone()' instead of 'sayHi()'. It doesn't always seem to be 'clone()', though; using the Jython interpreter, it seems that calling 'length()' on a java.lang.String object invokes 'equals()' instead:
Unfortunately, I don't understand Kaffe's internals well enough to be able to fix this bug. But I hope that these findings will make fixing it easier...Jython 2.1 on java1.1.x-cvs (JIT: kaffe.jit) Type "copyright", "credits" or "license" for more information.import java
s = java.lang.String("hi") s.length()
Traceback (innermost last): File "<console>", line 1, in ? java.lang.NullPointerException at java.lang.String.equals(String.java:214) at java.lang.reflect.Method.invoke0(Method.java:native) at java.lang.reflect.Method.invoke(Method.java:256) at org.python.core.PyReflectedFunction.__call__(PyReflectedFunction.java:line unknown, pc 0x84d8701) at org.python.core.PyMethod.__call__(PyMethod.java:line unknown, pc 0x84bec38) at org.python.core.PyObject.__call__(PyObject.java:line unknown, pc 0x84ac642) at org.python.core.PyInstance.invoke(PyInstance.java:line unknown, pc 0x88c234f) at org.python.pycode._pyx3.f$0(<console>:1) at org.python.pycode._pyx3.call_function(<console>:line unknown, pc 0x82a16cf) at org.python.core.PyTableCode.call(PyTableCode.java:line unknown, pc 0x86f25eb) at org.python.core.PyCode.call(PyCode.java:line unknown, pc 0x83605df) at org.python.core.Py.runCode(Py.java:line unknown, pc 0x8d7c37b) at org.python.core.Py.exec(Py.java:line unknown, pc 0x8d7c1bc) at org.python.util.PythonInterpreter.exec(PythonInterpreter.java:line unknown, pc 0x87f0f23) at org.python.util.InteractiveInterpreter.runcode(InteractiveInterpreter.java:line unknown, pc 0x8da5062) at org.python.util.InteractiveInterpreter.runsource(InteractiveInterpreter.java:line unknown, pc 0x8d7961d) at org.python.util.InteractiveInterpreter.runsource(InteractiveInterpreter.java:line unknown, pc 0x8301a37) at org.python.util.InteractiveConsole.push(InteractiveConsole.java:line unknown, pc 0x8d7b2ea) at org.python.util.InteractiveConsole.interact(InteractiveConsole.java:line unknown, pc 0x8d56268) at org.python.util.jython.main(jython.java:line unknown, pc 0x8267b9d)java.lang.NullPointerException: java.lang.NullPointerException
Hoping to get our project (http://gzz.info/) to run on a completely free system soon,
- Benja
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