module type X = sig type t end
module F = functor (X : X) -> struct include X end
module A = F (struct type t = int * int end)
module B = F (struct type t = { x : int; y : int } end)

module type X = sig type t end
module F : functor (X : X) -> sig type t = X.t end
module A : sig type t = int * int end
module B : sig type t end