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kotlinlang

:wave: Hi everyone!
The following code compiles, but fail at runtime (Kotlin 2.2.0 on jvm with IntelliJ 2025.2 Beta Community Edition):
```object Parent {
    val instance = MyObject(Child.childValue)
    val parentValue = "other"

    object Child {
        val childValue = parentValue
    }
}

data class MyObject(
    val value: String,
)

fun main() {
    println(Parent.Child.childValue)
}```
Is it an expected behavior? Shouldn't the compilation fail instead?

Here is the stacktrace:
```Exception in thread "main" java.lang.ExceptionInInitializerError
	at Parent$Child.<clinit>(Main.kt:6)
	at MainKt.main(Main.kt:15)
	at MainKt.main(Main.kt)
Caused by: java.lang.NullPointerException: Parameter specified as non-null is null: method MyObject.<init>, parameter value
	at MyObject.<init>(Main.kt)
	at Parent.<clinit>(Main.kt:2)```

It is expected behaviour. JVM specification for class static members initialization sequence.

~Effectively, the `Parent` on instantiation triggers the `Child` to be instantiated (via the usage of `Child.childValue` ) - at the point of `Child.childValue` being instantiated, the static value for the parent instance hasn't been instantiated and the value of `parentValue` is still null - resulting in that null being stored on the `childValue` and subsequently passed to `MyObject` constructor.~
The above is subtly wrong in this case.
By referencing `Child` the JVM will attempt to instantiate it, at which point it's `<init>` method will reference `Parent.parentValue` which triggers instantiation of `Parent` . `Parent.<init>` references an already-instantiating `Child` field which has yet to be populated (as the JVM is still instantiating `Parent` from which it will acquire the value to populate on `childValue`) and as such it's still `null` when being passed to `MyObject`)

if you remove the `val instance = MyObject(Child.childValue)` or make it lazy `val instance by lazy { MyObject(Child.childValue) }` it should work

Guessing you are seeing this?
<https://youtrack.jetbrains.com/issue/KT-8970/Object-is-uninitialized-null-when-accessed-from-static-context-ex.-companion-object-with-initialization-loop>