(* TEST
 expect;
*)

(* #13185 *)

module type S1 = sig end
module type S2 = functor (X : S1) -> sig module M = X end
[%%expect{|
module type S1 = sig end
Line 2, characters 41-53:
2 | module type S2 = functor (X : S1) -> sig module M = X end
                                             ^^^^^^^^^^^^
Error: Functor arguments, such as "X", cannot be aliased
|}]