is it intended behavior that

fun ParseNode.accept(visitor: Visitor){
    when(this){
        is NodeTypeA -> this.internalAccept(visitor::visitEnter, visitor::visitLeave)
    }
}

private fun <T> T.internalAccept(enter: (T) -> Unit, leave: (T) -> Unit): Unit = TODO()

will not compile without the

this.

infront of

internalAccept

? It seems like theres a corner case I'm hitting between smart casting and type inference that isnt covered here.

groostav: What error message do you get when trying to compile it?

if you remove the

this.

from the third line, then

Error:(31, 50) Kotlin: None of the following functions can be called with the arguments supplied:

public final fun visitEnter(node: NodeTypeA): Unit defined in com.empowerops.Visitor

public final fun visitEnter(node: NodeTypeB): Unit defined in com.empowerops.Visitor

and so on