False-negative conflicting base types when inherits Java class and interface.

[XYZboom]

Compiler version

3.6.3-RC2, 3.6.4-RC1-bin-20241231-1f0c576-NIGHTLY

Minimized code

// FILE: I0.java
public interface I0<T> {
    public default T func(T t) {
        return t;
    }
}
// FILE: I1.java
public interface I1 extends I0<String> {
    @Override
    default String func(String s) {
        return s;
    }
}

abstract class A0 extends I1 with I0[Object] {
  override def func(s: Object): String = super.func(s)
}

Output

passed

Expectation

error: class A0 has conflicting base types I0[String] and I0[Object].
We can see a similar but not very clear error in scala2:

illegal inheritance;
 self-type A0 does not conform to I0[Object]'s selftype I0[Object]

[He-Pin]

this should be an override nothing too

[sjrd]

That error is legit. IO is invariant, so a class cannot be both an IO[Object] and an IO[String].

[XYZboom]

That error is legit. IO is invariant, so a class cannot be both an IO[Object] and an IO[String].

Yes, so the compiler should not passed the above code. That's why I said false-negative.

[sjrd]

Oops, you're right. I misread the issue.