This works with legacy backend but not with IR: ``...

# javascript

[Robert Jaros]

This works with legacy backend but not with IR:

external interface BtOn {
}

interface SnOn<T> : BtOn {
    var self: T
}

@Suppress("UnsafeCastFromDynamic")
fun on(target: Any): SnOn<Any> {
    val obj = js("{}")
    obj["self"] = target
    return obj
}

fun main() {
    val x = on("test");
    console.log(x.self);
}

It fails with x._get_self_ is not a function. Is it a bug in the compiler backend or is my code just wrong?

[diesieben07]

Your code is wrong, as you are relying on compiler internals (self property is translated to a JS property named the same). You have to use external interface to describe raw JS objects.

[andylamax]

Actually that's an IR bug. This should work out of the box. You should mark SnOn<T> as an external interface just as a workarround. This same problem is being faced by the kotlin-react js wrapper and they gave that workaround

[diesieben07]

How is it an IR bug? interface describes a full-blown instance of a class. Not just any random object with some properties.

[andylamax]

This link https://kotlinlang.slack.com/archives/C0B8L3U69/p1585318146030900, explains why (though in another context apart from this)