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

I'm not sure but that seems to be a bug due to smart casting (to Nothing?, subtype of every nullable type). This one works:

fun main(args: Array) {
    var ab: String? = "hello"
    ab = makeNull()
    println(ab?.toUpperCase())
}

fun makeNull(): String? = null

The only difference: The compiler does not know the null assignment directly, which seems to cause the error in your example. But still, yours should probably work too.