Kotlin 1.3.11 has broken null-safety?

Question

fun handle() : String {
    null?.let { return "Ololo"}
}

val result = handle()
result.trim() // kotlin.TypeCastException: null cannot be cast to non-null type kotlin.CharSequence

Any ideas why null-safe Kotlin function return null?

Answer 1

It's a bug caused by introducing contracts for the standard functions let, run, apply, also in Kotlin 1.3.

The fix is targeted to the version 1.3.20. See KT-28061 for details.