class A {
    fun B.foo() {}
}

interface B

fun bar(a: A, b: B) {
    with (a) {
        b.<caret>foo()
    }
}


Resolved call:

Resulting descriptor: fun B.foo(): Unit defined in A

Explicit receiver kind = EXTENSION_RECEIVER
Dispatch receiver = AExt{fun A.`<anonymous>`(): Unit defined in bar}
Extension receiver = b {B}