Cannot override JavaClass that overrides method with omitted generics

[SrTobi]

Compiler version

3.7.3

Minimized code

JavaImpl.java

import java.lang.ref.Reference;

public abstract class JavaImpl implements Comparable<Reference<Object>> {
    @Override
    public int compareTo(Reference ref) { // <Object> is omitted
        return 0;
    }
}

ScalaImpl.scala

class ScalaImpl extends JavaImpl

Output

class ScalaImpl needs to be abstract, since def compareTo(x$0: T): Int in trait Comparable in package java.lang is not defined 
(Note that
 parameter T in def compareTo(x$0: T): Int in trait Comparable in package java.lang does not match
 parameter java.lang.ref.Reference[?] in def compareTo(ref: java.lang.ref.Reference[?]): Int in class JavaImpl
 )
class ScalaImpl extends JavaImpl

Expectation

Should just compile. Note that new JavaImpl works in scala... here the compiler doesn't complain.

I understand that the scala compiler has a point with its error, but is ultimately wrong in this case and completely prevents me from overriding this class. As far as I can see there is nothing I can do (neither in scala nor in java (except from changing the method)) to implement JavaImpl in any way.

[SrTobi]

Also note that this used to work in Scala 2

[He-Pin]

I think this is right, what about adding the <Object> to Reference ref?

[SrTobi]

Then it works and I wouldn't open this issue. Unfortunately in my case the class that I minimized to JavaImpl is in a library 😑

[He-Pin]

What about you override it in Scala

[SrTobi]

I can't override it... if I do override def compareTo(ref: Reference[Object]): Int it tells me that it clashes with the other function after type erasure.

[He-Pin]

Just tired, I can't get it to work too:(, there are many raw types been used in Java code.

[sjrd]

I wouldn't put my hopes up for this getting fixed. Java raw types have been deprecated for longer than Scala has existed. They pose huge issues for the type system. Scala 2 tried very hard to "cook" raw types (raw ... cook ... get it?) to kind-of make sense of them, but it was best effort. I don't think we would complicate Scala 3 with a half-baked solution. (@som-snytt are you proud of me?)

[He-Pin]

I think we can make it compiled with another Java class glue