kotlin-fork/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/receiver.fir.kt

// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
// !WITH_NEW_INFERENCE

import kotlin.contracts.*

fun Any?.isNull(): Boolean {
    contract {
        returns(false) implies (this@isNull != null)
    }
    return this == null
}

fun smartcastOnReceiver(x: Int?) {
    if (x.isNull()) {
        x.<!AMBIGUITY!>inc<!>()
    }
    else {
        x.dec()
    }
}

class UnstableReceiver {
    var x: Int? = 42

    fun smartcastOnUnstableReceiver() {
        if (x.isNull()) {
            x.<!AMBIGUITY!>inc<!>()
        }
        else {
            x.<!AMBIGUITY!>dec<!>()
        }
    }
}