Name: rmT116609 Date: 07/29/2003


FULL PRODUCT VERSION :
java version "1.4.2"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2-b28)
Java HotSpot(TM) Client VM (build 1.4.2-b28, mixed mode)

generics prototype compiler 2.2-ea

FULL OS VERSION :
Windows XP

A DESCRIPTION OF THE PROBLEM :
I am using the generics prototype compiler version 2.2-ea and the specification that comes with it.

According to section 5.4 of the spec the following code should give an error message, because I cast to a parameterized subtype of Object and there are other subtypes of Object with the same erasure. Such a cast is illegal according to the spec and I had expected a compiletime error message.



public class Test{

private static class GenericWrapper<Elem> {
private Elem theObject;
public GenericWrapper(Elem arg) {
theObject = arg;
}
public <T extends Elem> GenericWrapper (GenericWrapper<T> other) {
this.theObject = other.theObject;
}
public String toString() {
return theObject.toString();
}
}
private static GenericWrapper<String> method (Object wrappedString) {
return (GenericWrapper<String>) wrappedString;
}

public static void main(String[] args) {
System.out.println(method(new GenericWrapper<String>("abc")));
System.out.println(method(new GenericWrapper<Exception>(new Exception())));
}
}



By the way, I do not get a runtime error either.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
compile the code

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The compiler is supposed to reject the following cast from Object to a parameterized type:

(GenericWrapper<String>) wrappedString
ACTUAL -
no error messages whatsoever, neither at compiletime nor at runtime

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
public class Test{

private static class GenericWrapper<Elem> {
private Elem theObject;
public GenericWrapper(Elem arg) {
theObject = arg;
}
public <T extends Elem> GenericWrapper (GenericWrapper<T> other) {
this.theObject = other.theObject;
}
public String toString() {
return theObject.toString();
}
}
private static GenericWrapper<String> method (Object wrappedString) {
return (GenericWrapper<String>) wrappedString;
}

public static void main(String[] args) {
System.out.println(method(new GenericWrapper<String>("abc")));
System.out.println(method(new GenericWrapper<Exception>(new Exception())));
}
}
---------- END SOURCE ----------
(Incident Review ID: 192975)
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