(* TEST
 expect;
*)

module F(S : sig type 'a t end) = struct
  type _ ab =
      A : int S.t ab
    | B : float S.t ab

  let f : int S.t ab -> float S.t ab -> string =
    fun (l : int S.t ab) (r : float S.t ab) -> match l, r with
    | A, B -> "f A B"
end;;
[%%expect{|
Lines 7-8, characters 47-21:
7 | ...............................................match l, r with
8 |     | A, B -> "f A B"
Warning 8 [partial-match]: this pattern-matching is not exhaustive.
  Here is an example of a case that is not matched: "(A, A)"

module F :
  (S : sig type 'a t end) ->
    sig
      type _ ab = A : int S.t ab | B : float S.t ab
      val f : int S.t ab -> float S.t ab -> string
    end
|}];;

module F(S : sig type 'a t end) = struct
  type a = int * int
  type b = int -> int

  type _ ab =
      A : a S.t ab
    | B : b S.t ab

  let f : a S.t ab -> b S.t ab -> string =
    fun l r -> match l, r with
    | A, B -> "f A B"
end;;
[%%expect{|
Lines 10-11, characters 15-21:
10 | ...............match l, r with
11 |     | A, B -> "f A B"
Warning 8 [partial-match]: this pattern-matching is not exhaustive.
  Here is an example of a case that is not matched: "(A, A)"

module F :
  (S : sig type 'a t end) ->
    sig
      type a = int * int
      type b = int -> int
      type _ ab = A : a S.t ab | B : b S.t ab
      val f : a S.t ab -> b S.t ab -> string
    end
|}];;
