I have a DSL function whose lambda returns

Any?

allowing any object to be returned. This lambda's receiver is also a DSL type meaning there are functions you can call inside of it. The problem is that these functions return

Unit

thus completing the contract of the enclosing lambda and avoiding the need to actually return an object. Is there any way to avoid this?

@MyDsl interface Foo {
  fun bar(lambda: Bar.() -> Any?)
}
@MyDsl interface Bar {
  fun someHelper(size: Int)
  fun otherHelper(flag: Boolean)
}

bar {
  someHelper(2)
  otherHelper(true)
  // should be required to return an object here
}

I tried to get clever with an overload of

bar

whose lambda returned

Unit

and was marked as an error, but you can't

@JvmName

an interface function. converting it to a class results in the

Unit

-returned lambda always being preferred. There's a Kotlin-internal annotation to lower its overload precedence, but I don't have access to that.

I got a bit further by taking both

Any?

and

Unit

methods out of the interface letting you

JvmName

them it seems return type inference isnt quite up to it.

@MyDsl interface Foo {
    fun internalMethod()
}
@JvmName("asdasd")
@Deprecated("You must return something", level = DeprecationLevel.ERROR)
fun Foo.bar(lambda: Bar.() -> Unit) = Unit

@JvmName("asd")
fun Foo.bar(lambda: Bar.() -> Any?){
    internalMethod()
}


@MyDsl interface Bar {
    fun someHelper(size: Int)
    fun otherHelper(flag: Boolean)
}

fun Foo.f() {
    bar {
        someHelper(2)
        otherHelper(true)
        // should be required to return an object here
        "2"
    }
}