#                 class type foo_t = object method foo : string end
type 'a name = Foo : foo_t name | Int : int name
#                   class foo :
  object method cast : foo_t name -> < foo : string > method foo : string end
#                   Characters 22-184:
  ..object(self)
      method foo = "foo"
      method cast: type a. a name -> a =
        function
            Foo -> (self :> foo_t)
          | _ -> ((raise Exit) : a)
    end
Error: The class type
         object method cast : 'a name -> 'a method foo : string end
       is not matched by the class type foo_t
       The public method cast cannot be hidden
#