'operator' checks

compiler/testData/diagnostics/tests/smartCasts/varnotnull/prefixNotnullClassIncrement.kt

@@ -1,13 +1,12 @@
 class MyClass
 
-// In principle it is not correct, MyClass? is not a subtype of MyClass
-operator fun MyClass.inc(): MyClass? { return null }
+operator fun MyClass.inc(): MyClass { <!UNREACHABLE_CODE!>return<!> null!! }
 
 public fun box() {
-    var i : MyClass? 
+    var i : MyClass?
     i = MyClass()
     // Type of j should be inferred as MyClass?
     var j = ++<!DEBUG_INFO_SMARTCAST!>i<!>
     // j is null so call is unsafe
-    j<!UNSAFE_CALL!>.<!>hashCode()
-}
+    j.hashCode()
+}