glureau / KotlinJsTesting

Personal sandbox for testing new KotlinJs versions

Issue

Upgrading Kotlin from 1.6.10 to 1.6.20-RC2 brings runtime crash on a specific context.

It has been tested on a JS/IR library, executed via ts-node.

Context

A class annotated with @JsExport that uses internal lateinit var. Fill this field with an implementation in the init block.

KT 1.6.10: works as expected

KT 1.6.20-RC2: crash with

TypeError: Cannot read properties of undefined (reading 'someData_1')

Reproducer

A reproducer can be found in this repository. To reproduce, you just need to run ./buildAndRun.sh script.

Code

(just a copy-paste from the relevant parts)

main.kt :

class NonExportedClass { val someData = 12 }

@JsExport
class Foo {
    internal lateinit var nec: NonExportedClass

    init {
        nec = NonExportedClass()
    }

    val exposedValue: Int get() = nec.someData
}

main.ts :

var t = new testing.Foo()
//KT 1.6.10: print "12"
//KT 1.6.20-RC2: TypeError: Cannot read properties of undefined (reading 'someData_1')
console.log(t.exposedValue)