eio: Remove the use of 'Eio_unix.Fd.of_unix'

There's no easy way for opening a `Flow` through a `Eio_unix.Fd.t`.
Instead, use `Eio_unix.Net.import_socket_stream` to create a `Flow` from
a `Unix.file_descr` directly.

Author: Julow

bin/lwt_to_direct_style/concurrency_backend.ml

@@ -169,22 +169,24 @@ let eio ~eio_sw_as_fiber_var ~eio_env_as_fiber_var add_comment =
 
     method direct_style_type param = param
 
-    method of_unix_file_descr ?blocking fd =
-      let blocking_arg =
-        let lbl = mk_loc "blocking" in
-        match blocking with
-        | Some (expr, `Lbl) -> [ (Labelled lbl, expr) ]
-        | Some (expr, `Opt) -> [ (Optional lbl, expr) ]
-        | None -> []
-      in
-      mk_apply_ident
-        [ "Eio_unix"; "Fd"; "of_unix" ]
-        ([ get_current_switch_arg () ]
-        @ blocking_arg
-        @ [
-            (Labelled (mk_loc "close_unix"), mk_constr_exp [ "true" ]);
-            (Nolabel, fd);
-          ])
+    method of_unix_file_descr ?blocking:_ fd =
+      (* TODO: We don't use [Eio_unix.Fd.t] because there is no conversion to [Flow.sink]. *)
+      (* let blocking_arg = *)
+      (*   let lbl = mk_loc "blocking" in *)
+      (*   match blocking with *)
+      (*   | Some (expr, `Lbl) -> [ (Labelled lbl, expr) ] *)
+      (*   | Some (expr, `Opt) -> [ (Optional lbl, expr) ] *)
+      (*   | None -> [] *)
+      (* in *)
+      (* mk_apply_ident *)
+      (*   [ "Eio_unix"; "Fd"; "of_unix" ] *)
+      (*   ([ get_current_switch_arg () ] *)
+      (*   @ blocking_arg *)
+      (*   @ [ *)
+      (*       (Labelled (mk_loc "close_unix"), mk_constr_exp [ "true" ]); *)
+      (*       (Nolabel, fd); *)
+      (*     ]) *)
+      fd
 
     method io_read input buffer buf_offset buf_len =
       add_comment "[%s] should be a [Cstruct.t]."
@@ -193,7 +195,9 @@ let eio ~eio_sw_as_fiber_var ~eio_env_as_fiber_var add_comment =
       add_comment_dropped_exp ~label:"buffer length" buf_len;
       mk_apply_simple [ "Eio"; "Flow"; "single_read" ] [ input; buffer ]
 
-    method fd_close fd = mk_apply_simple [ "Eio_unix"; "Fd" ] [ fd ]
+    method fd_close fd =
+      (* TODO: See [of_unix_file_descr]. mk_apply_simple [ "Eio_unix"; "Fd" ] [ fd ] *)
+      mk_apply_simple [ "Unix"; "close" ] [ fd ]
 
     method main_run promise =
       let with_binding var_ident x body =

test/lwt_to_direct_style/eio-switch.t/run.t

@@ -30,11 +30,7 @@ Make a writable directory tree:
     Fiber.fork
       ~sw:(Stdlib.Option.get (Fiber.get Fiber_var.sw))
       (fun () -> async_process 1);
-    let fd =
-      Eio_unix.Fd.of_unix
-        ~sw:(Stdlib.Option.get (Fiber.get Fiber_var.sw))
-        ~close_unix:true Unix.stdin
-    in
+    let fd = Unix.stdin in
     let in_chan =
       (Eio_unix.Net.import_socket_stream
          ~sw:(Stdlib.Option.get (Fiber.get Fiber_var.sw))

test/lwt_to_direct_style/to_direct_style.t/run.t

@@ -677,11 +677,7 @@ Make a writable directory tree:
   
   let _f fname =
     let inp =
-      Eio_unix.Fd.of_unix ~sw ~close_unix:true
-        (Unix
-         (* TODO: lwt-to-direct-style: [sw] (of type Switch.t) must be propagated here. *).(
-           openfile fname [ O_RDWR; O_NONBLOCK; O_APPEND ])
-           0o660)
+      Unix.(openfile fname [ O_RDWR; O_NONBLOCK; O_APPEND ]) 0o660
       |>
       (* TODO: lwt-to-direct-style: [sw] (of type Switch.t) must be propagated here. *)
       (* TODO: lwt-to-direct-style: This creates a closeable [Flow.source] resource but read operations are rewritten to calls to [Buf_read]. *)