(* TEST_BELOW
(* Blank lines added here to preserve locations. *)







*)

type a = { mutable a : int }

let mutable_pat1 {a} b = a + b

let mutable_pat2 b {a} = b + a

let measure name f =
  let a = {a = 1} in
  let b = 2 in
  let before = Gc.minor_words () in
  let (_ : int) = f ~a ~b in
  let after = Gc.minor_words () in
  let alloc = int_of_float (after -. before) in
  match alloc with
  | 0 -> Printf.printf "%S doesn't allocate\n" name
  | _ -> Printf.printf "%S allocates\n" name

let () =
  measure "mutable_pat1" (fun ~a ~b -> mutable_pat1 a b);
  measure "mutable_pat2" (fun ~a ~b -> mutable_pat2 b a)

(* TEST
 flags = "-w +A-70";
 setup-ocamlopt.byte-build-env;
 ocamlopt.byte;
 run;
 check-program-output;
*)