Tail Modulo Constructor is only available from ocaml 4.13. Convert to…

… use seq under the assumption that List.of_seq is well optimized.

src/ocaml_protoc_plugin/extensions.ml

@@ -17,7 +17,7 @@ let set: ('a -> Writer.t, Writer.t) Serialize.S.compound_list -> t -> 'a -> t =
   let writer = Serialize.serialize [] spec [] writer v in
   let reader = Writer.contents writer |> Reader.create in
   match Reader.to_list reader with
-  | (((index, _) :: _) as fields) ->
-    (List.filter ~f:(fun (i, _) -> i != index) t) @  fields
+  | ((index, _) :: _) as fields ->
+    (List.filter ~f:(fun (i, _) -> i != index) t) @ fields
   | [] -> t
   | exception Result.Error _ -> failwith "Internal serialization fail"

src/ocaml_protoc_plugin/reader.ml

@@ -113,13 +113,11 @@ let read_field : boxed -> t -> int * Field.t = fun boxed ->
     let (field_type, field_number) = read_field_header t in
     field_number, read_field_content field_type t
 
-
 let to_list: t -> (int * Field.t) list =
   let read_field = read_field Boxed in
-  fun t ->
-  (* Make this tailrec *)
-  let[@tail_mod_cons] rec inner () = match has_more t with
-    | true -> read_field t :: inner ()
-    | false -> []
+  let rec next t () = match has_more t with
+    | true -> Seq.Cons (read_field t, next t)
+    | false -> Seq.Nil
   in
-  inner ()
+  fun t ->
+    next t |> List.of_seq