I'm getting Overload resolution ambiguity error on kotlin safe call

Question

I have a nullable string variable ab. If I call toUpperCase via safe call operator after I assign null to it, kotlin gives error.

fun m         


        

Answer 1

It really seems like a bug. The type String? is lost somehow upon assigning null, so you have to tell the compiler explicitely that it should deal with a String?.

fun main(args: Array){
    var ab: String? = "hello"
    ab = null
    println((ab as String?)?.toUpperCase()) // explicit cast

    // ...or

    println(ab?.let { it.toUpperCase() }) // use let
}