Name: rmT116609 Date: 05/27/2003


FULL PRODUCT VERSION :
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2-beta-b19)
Java HotSpot(TM) Client VM (build 1.4.2-beta-b19, mixed mode)

FULL OS VERSION :
SunOS 5.8 Generic_108528-15 sun4u sparc SUNW,Ultra-5_10
Windows XP

A DESCRIPTION OF THE PROBLEM :
The javac compiler in 1.4.2-beta reports an ambiguous method call error for abstract classes that implement an interface and have methods with the same name as in the interface but use a superclass for a corresponding argument.

The same code previously compiled without error under 1.4.1's compiler.

A quick check of the JLS did not seem to indicate one definite expected result for this particular situation, but even if the new behaviour is the correct behaviour, this should be indicated in the release notes for 1.4.2-beta as a source-level incompatibility between 1.4.2-beta and 1.4.1.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Create an interface with a method that has a certain subclass as an argument.

Create an abstract class that implements that interface. Add a method of the same name as above, but using a superclass of the above subclass as the corresponding argument. Make a call within a method of the abstract class to the method in question, with an instance of the subclass.

Compile the same source under J2SDK1.4.1 and J2SDK1.4.2-beta.

Simple source code of this scenario is included below.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Successful compilation with no errors reported, as under 1.4.1.
ACTUAL -
Compilation under 1.4.2-beta was unsuccessful, with an ambiguous method reference error reported.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Incompatible.java:10: reference to foo is ambiguous, both method foo(java.lang.String) in NotCompatible and method foo(java.lang.Object) in Incompatible match
                this.foo(o.toString());
                ^
1 error

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
interface NotCompatible
{
void foo(String s);
}

abstract class Incompatible implements NotCompatible
{
public void foo(Object o)
{
this.foo(o.toString());
}
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
If an explicit declaration of an abstract method matching the signature of the method in the interface is added to the abstract class, compilation is successful with no error messages.

Release Regression From : 1.4.1_02
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: 186521)
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