Hello

I try to inline some module application. It works when
I compile with ocamlopt or ocamlc manually:

ocamlopt -w a -warn-error a mat.ml test.ml

But fails using dune:

dune build

gives this error without flambda:

File "test.ml", line 12, characters 18-52:
12 | module FloatMat = Mat.Make [@inlined always] (Float)
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error (warning 55): Cannot inline: Unknown function

and this error with flambda:

File "test.ml", line 12, characters 18-52:
12 | module FloatMat = Mat.Make [@inlined always] (Float)
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error (warning 55): Cannot inline: [@inlined] attribute was not used on this function application (the optimizer did not know what function was being applied)

Am I missing something ?

Here are the files to reproduce:

------------------------- mat.ml ----------------------
module type Field = sig
  type t

  val zero : t
  val one : t
  val ( + ) : t -> t -> t
  val ( * ) : t -> t -> t
end

module Make (R:Field) = struct
  open R

  type v = t array
  type m = t array array

  let ( *. ) v1 v2 =
    let r = ref zero in
    for i = 0 to Array.length v1 do
      r := !r + v1.(i) * v2.(i)
    done;
    !r

  let ( ** ) m v = Array.map (fun w -> w *. v) m
end
--------------------------------------------------------

------------------------- test.ml ----------------------
module Float = struct
  type t = float

  let zero = 0.0
  let one  = 1.0

  let ( + ) = ( +. )
  let ( * ) = ( *. )
end

module FloatMat = Mat.Make [@inlined always] (Float)
--------------------------------------------------------

------------------------- dune -------------------------
; Add project-wide flags here.
(env
  (dev     (flags :standard -w -9-32)
           (ocamlopt_flags -O3))
  (release (flags :standard -w -9-32)
           (ocamlopt_flags -O3)))

(executable
  (name Test)
  (modules :standard))
---------------------------------------------------------