Warning 5 and a typing error on local open

[hyphenrf]

minimal example:

let rec product xs = (*(* uncomment me for a bug: *) let open Seq in *)
  match xs () with
  | Seq.Nil -> 1
  | Cons(0, _) -> 0
  | Cons(x, xs) -> x * product xs

I don't think this is normal behaviour?
Tested on 4.14, and trunk. Behaviour doesn't happen on 4.13.1

[hyphenrf]

Here's the specific error:

File "test.ml", line 11, characters 23-33:
11 |   | Cons(x, xs) -> x * product xs
                            ^^^^^^^^^^
Warning 5 [ignored-partial-application]: this function application is partial,
maybe some arguments are missing.
File "test.ml", line 11, characters 23-33:
11 |   | Cons(x, xs) -> x * product xs
                            ^^^^^^^^^^
Error: This expression has type 'a Seq.t -> (int * 'a) Seq.t
       but an expression was expected of type int

[nojb]

This is not a bug, it is due to the introduction of Seq.product in 4.14 (see #10583).

[hyphenrf]

oh of course, and the local open shadows the recursive call. My bad!