Is there an easy way to highlight or find out which object is being passed as the receiver in IDEA? In my usual cases I can easily have ten nested scopes

you can do CTRL-SHIFT-P with the caret within the block, which will give you the type of the lambda

latest plugin has hints for lambdas https://blog.jetbrains.com/kotlin/2018/01/kotlin-1-2-20-is-out/

The case is something like this:

foo { // this: Foo
bar { // this: Bar
baz { // this: Baz
moo()
}
}
}

moo()

takes something as receiver that either

Foo

,

Bar

or

Baz

satisfies. I would just like something nice like Ctrl + B for variables but since I cannot select the receiver then I cannot use that.

doesn’t CTRL-SHIFT-P work for you? I’d thought if you put the caret before

moo()

you’d see something like

Baz.() -> Unit

Yes but the receiver of moo can also be

Foo

or

Bar

. Consider

fun CharSequence.moo() {}

and

interface Foo : CharSequence