Kotlin sealed interface with generic type doesn't infer constraints for it's subtypes

Example:

sealed interface Foo<out T> {
    val value: T
}

data class Bar<out K: List<Int>>(override val value: K): Foo<K>
    
fun <T> processFoo(foo: Foo<T>) {
    
    when (foo) {
        is Bar -> foo.value.forEach(::println)
    }
}

Fails with:

Unresolved reference. None of the following candidates is applicable
because of receiver type mismatch:

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• public inline fun <T> Iterable<TypeVariable(T)>.forEach(action: (TypeVariable(T)) -> Unit): Unit defined in kotlin.collections
• public inline fun <K, V> Map<out TypeVariable(K), TypeVariable(V)>.forEach(action: (Map.Entry<TypeVariable(K), TypeVariable(V)>) -> Unit): Unit defined in kotlin.collections

Why this fails? I expect that if foo is of type Bar then we know that T is a subtype of List<Int>. So we should be able to call forEach on it. Am I wrong?

>Solution :

This problem is simply caused by a typo in your code.

If you replace is Bar with is Bar<*>, the compiler is able to infer that T is a List<Int> in that context and the code compiles.