• Accessing a non-final property during class initialization: from a constructor or property initialization
• Calling a non-final function during class initialization
• Using this as a function argument in a constructor of a non-final class

If other classes inherit from the given class, they may not be fully initialized at the moment when an unsafe operation is carried out.

Example:

  abstract class Base {
      val code = calculate()
      abstract fun calculate(): Int
  }

  class Derived(private val x: Int) : Base() {
      override fun calculate() = x
  }

  fun testIt() {
      println(Derived(42).code) // Expected: 42, actual: 0
  }