class A { fun dynamic.foo() {} } fun bar(a: A, b: dynamic) { with (a) { with (b) { foo() } } } Resolved call: Resulting descriptor: fun dynamic.foo(): Unit defined in A Explicit receiver kind = NO_EXPLICIT_RECEIVER Dispatch receiver = AExt{fun A.(): Unit defined in bar} Extension receiver = ('Nothing'..'Any?')Ext{fun dynamic.(): Unit defined in bar.}