(* TEST
 expect;
*)
type u = <x:int>
type t = private <u; ..>

let f (x:t) (y:u) = x = y;;
[%%expect{|
type u = < x : int >
type t = private < x : int; .. >
Line 4, characters 24-25:
4 | let f (x:t) (y:u) = x = y;;
                            ^
Error: The value "y" has type "u" but an expression was expected of type "t"
       The second object type has an abstract row, it cannot be closed
|}]


let g (x:u) (y:t) = x = y;;
[%%expect{|
Line 1, characters 24-25:
1 | let g (x:u) (y:t) = x = y;;
                            ^
Error: The value "y" has type "t" but an expression was expected of type "u"
       The first object type has an abstract row, it cannot be closed
|}]