### code.ml [ocaml]
module type M1 =
sig
  type t

  module type M2 =
  sig
    type t
  end
end

module Make (I1: M1) =
struct
  module I2 = I1.M2
  type t_arr = I2.array
end

### error.txt
File "code.ml", line 14, characters 14-19:
Error: Unbound module I1.M2