Java interop issue: illegal inheritance error

[scabug]

An Illegal inheritance error is thrown by the compiler trying to inherit java classes/ interfaces in the following way:

interface A<T>{}

interface B<T> extends A<T>{}

interface C extends A{}

class D implements B,C {
	public D(){};
}

Trying to subclass D in scala:

scala> class Foo extends D
<console>:7: error: illegal inheritance;
 class Foo inherits different type instances of trait A:
A[T] and A[T]
       class Foo extends D
             ^

The problem appeared when trying to subclass org.apache.commons.buffer.PriorityBuffer, so there are real life situations where this leads to scala<->java interop problems.

http://commons.apache.org/collections/apidocs/org/apache/commons/collections/buffer/PriorityBuffer.html

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-4937?orig=1
Reporter: Daniel Degrandi (danieldegrandi)
Affected Versions: 2.9.0-1

[scabug]

@soc said (edited on Aug 25, 2011 11:07:45 AM UTC):
This looks at least related to #3634, which involves raw types. I'm pretty sure though, that there are also other duplicates about this ...

The source code in the source jar defines:

public class PriorityBuffer extends AbstractCollection implements Buffer, Serializable { ... }

So basically:

• this involves raw types, which are not supported in Scala
• Sun/Oracle reserves the right to remove support of raw types from javac in the future

=> this will most probably be a WON'T FIX
=> it is Apache's duty to fix it (but considering that the last release was 2008, I consider the library to be not maintained)

@daniel: Your best chance is to file a bug in Apache's bug tracker for it.

[scabug]

@paulp said:
Yes, there are a number of closed wontfix tickets.