I'm trying K2 with a multiplatform project (JS, Wasm). With the old compiler I can just declare

expect class NativeList<E> : MutableList<E>

in a common source set. But with K2 enabled I need to also declare all methods of the interface (which also works with the old compiler). Is it a bug?

It is by design You need to declare all abstract methods or make NativeList an abstract class

Noticed this too testing K2. I think it makes sense, more explicit on the intent