mcs/errors/cs0023-24.cs

   1 // CS0023: The `?' operator cannot be applied to operand of type `int'
   2 // Line: 9
   3
   4 public class C
   5 {
   6         static void Main()
   7         {
   8                 string s = null;
   9                 var x = s?.Length?.ToString ();
  10         }
  11 }