compiler/testData/codegen/box/extensionFunctions/kt1953.kt

// IGNORE_BACKEND_FIR: JVM_IR
// KJS_WITH_FULL_RUNTIME
fun box(): String {
    val sb = StringBuilder()
    operator fun String.unaryPlus() {
        sb.append(this)
    }

    +"OK"
    return sb.toString()!!
}