Update config.ml build to reduce complexity

Now `config.ml` and `dune.inc` are copied in their own `build-config`
directory, where `dune` is also generated. Tests don't rely anymore on
"include hacks".

app/functoria_app.ml

@@ -622,32 +622,34 @@ module Make (P: S) = struct
     with_fmt f
 
   (* Compile the configuration file. *)
-  let compile file_ml =
-    Log.info (fun m -> m "Compiling: %a" Fpath.pp file_ml);
-    let file = Dynlink.adapt_filename (Fpath.basename file_ml)
-    and cfg = Fpath.rem_ext file_ml
+  let compile file_ml_path =
+    let build_dir = get_build_dir () in
+    let build_root = Fpath.parent build_dir in
+    Log.info (fun m -> m "Compiling: %a" Fpath.pp file_ml_path);
+    let file = Dynlink.adapt_filename (Fpath.basename file_ml_path)
+    and cfg = Fpath.rem_ext file_ml_path
     and config_dir = Fpath.parent !config_file
-    and file_ml = Fpath.basename file_ml
+    and file_ml = Fpath.basename file_ml_path
     in
-    Bos.OS.Path.matches Fpath.(config_dir / "_build" // cfg + "$(ext)") >>= fun files ->
+    Bos.OS.Path.matches Fpath.(build_dir // cfg + "$(ext)") >>= fun files ->
     List.fold_left (fun r p -> r >>= fun () -> Bos.OS.Path.delete p) (R.ok ()) files >>= fun () ->
-    with_current config_dir
+    with_current build_root
       (fun () ->
-          let target_dir = Fpath.(v "_build")
+          let target_dir = Fpath.(v "build-config")
           (* Import files in the build target *)
-          and target_path = Fpath.(v "_build" / file_ml)
-          and target_path_dune = Fpath.(v "_build" / "config.dune")
+          and target_path = Fpath.(v "build-config" / file_ml)
+          and target_path_dune = Fpath.(v "build-config" / "config.dune")
           in
           Bos.OS.Dir.create target_dir >>= fun _ ->
-          Bos.OS.Path.symlink ~force:true ~target:(Fpath.(v ".." / file_ml)) target_path >>= fun () ->
-          Bos.OS.Path.exists Fpath.(v "config.dune") >>= fun res ->
+          Bos.OS.Path.symlink ~force:true ~target:(Fpath.(build_root // file_ml_path)) target_path >>= fun () ->
+          Bos.OS.Path.exists Fpath.(config_dir / "config.dune") >>= fun res ->
           (match res with
-          | true ->  (Bos.OS.Path.symlink ~force:true ~target:(Fpath.(v ".." / "config.dune")) target_path_dune >>= fun () -> Ok true)
+          | true ->  (Bos.OS.Path.symlink ~force:true ~target:(Fpath.(build_root // config_dir / "config.dune")) target_path_dune >>= fun () -> Ok true)
           | false -> Ok false)
           (* Generate dune configuration file *)
           >>= fun has_dune_inc ->
-          let dune_file = Fpath.(v "_build" / "dune")
-          and dune_project_file = Fpath.(v "_build" / "dune-project") in
+          let dune_file = Fpath.(v "build-config" / "dune")
+          and dune_project_file = Fpath.(v "dune-project") in
           let pkgs = match P.packages with
             | []   -> ""
             | pkgs ->
@@ -664,12 +666,14 @@ module Make (P: S) = struct
           let dune_content_default = "(library (name config) (modules config) (libraries "^pkgs^"))" in
           let dune_content = if has_dune_inc then ("(include config.dune)"^dune_content_default) else dune_content_default in
           let write_dune_file = Bos.OS.File.delete dune_file >>= fun () -> Bos.OS.File.write dune_file dune_content
-          and write_dune_project_file = Bos.OS.File.delete dune_project_file >>= fun () -> Bos.OS.File.write dune_project_file "(lang dune 1.7)"
+          and write_dune_project_file = Bos.OS.File.exists dune_project_file 
+          >>= function | false -> Bos.OS.File.write dune_project_file "(lang dune 1.7)" 
+                       | true  -> Ok ()
           in
-          (* Build config.cmxa with dune *)
-          let target_file = Fpath.(v "_build" / "default" / file) |> Fpath.to_string in
+          (* Build config.cmxs with dune *)
+          let target_file = Fpath.(v "_build" / "default" / "build-config" / file) |> Fpath.to_string in
           let cmd =
-            Bos.Cmd.(v "dune" % "build" % "--no-print-directory" % "--root" % "_build" % target_file)
+            Bos.Cmd.(v "dune" % "build" % "--root" % "." % target_file)
          in
          write_dune_project_file >>= fun () -> write_dune_file >>= fun () ->
          Bos.OS.Cmd.run_out cmd |> Bos.OS.Cmd.out_string >>= fun (out, status) ->
@@ -689,7 +693,7 @@ module Make (P: S) = struct
    * side effect to this command *)
   let dynlink file =
     let file = Dynlink.adapt_filename (Fpath.basename file) in
-    let file = Fpath.(to_string (parent !config_file / "_build" / "_build" / "default" / file)) in
+    let file = Fpath.(to_string (v "_build" / "default" / "build-config" / file)) in
     try Ok (Dynlink.loadfile file)
     with Dynlink.Error err ->
       let err = Dynlink.error_message err in

tests/app/config.dune

@@ -1,6 +1,5 @@
 (library
     (name config_custom)
+    (libraries functoria.test)
     (modules)
 )
-
-(env (_ (flags (-I ../../../../lib/.test_app.objs/byte -I ../../../../../lib/.functoria.objs/byte))))

tests/dune

@@ -11,5 +11,5 @@
  (modules   test_full)
  (libraries test_app alcotest cmdliner rresult astring)
  (package   functoria-runtime)
- (deps      app/config.ml app/app.ml app/config.dune ../runtime/functoria_runtime.ml ../runtime/functoria_info.ml)
+ (deps      app/config.ml app/app.ml app/config.dune (package functoria))
 )

tests/lib/dune

@@ -1,5 +1,7 @@
 (library
- (name      test_app)
- (libraries functoria.app)
- (wrapped   false)
+ (name          test_app)
+ (public_name   functoria.test)
+ (libraries     functoria.app)
+ (wrapped       false)
+ (modules       test_app)
 )

tests/lib/test_app.ml

@@ -46,7 +46,7 @@ let write_key i k f =
 
 let split_root () =
   let cwd = R.get_ok @@ Bos.OS.Dir.current () in
-  let root = Fpath.(root () / "_build" / "default") in
+  let root = root () in
   match Fpath.relativize ~root cwd with
   | None      -> failwith "split root"
   | Some path -> root, path
@@ -76,13 +76,9 @@ module C = struct
 
       method! configure i =
         let dune = Fmt.strf
-            "; An infortunate hack: bring stage 0 modules in scope of stage 1\n\
-             (rule (copy ../../runtime/functoria_runtime.ml functoria_runtime.ml))\n\
-             (rule (copy ../../runtime/functoria_info.ml functoria_info.ml))\n\
-             \n\
-             (executable\n\
+            "(executable\n\
             \   (name      %s)\n\
-            \   (libraries cmdliner fmt))\n"
+            \   (libraries cmdliner fmt functoria-runtime))\n"
             (output i)
         in
         Bos.OS.File.write (dune_file i) dune

tests/test_full.ml

@@ -86,8 +86,7 @@ let test_configure () =
   test "configure -vv --file app/config.ml";
   Alcotest.(check files) "new files should be created in the source dir"
     ["app.ml"; "config.ml"; "config.dune"; "key_gen.ml";
-     "main.ml"; ".mirage.config"; "dune"; "_build"
-    ] (list_files "app");
+     "main.ml"; ".mirage.config"; "dune"] (list_files "app");
  clean_app ();
 
   (* check that configure generates the file in the right dir when
@@ -96,8 +95,8 @@ let test_configure () =
   Alcotest.(check files) "the usual files should be present before configure"
     ["app.ml"; "config.ml"; "config.dune"] (list_files "app");
   test "configure -vv --file app/config.ml --build-dir custom_build_";
-  Alcotest.(check files) "only _build should be created in the source dir"
-    ["app.ml"; "config.ml"; "config.dune"; "_build"]
+  Alcotest.(check files) "nothing should be created in the source dir"
+    ["app.ml"; "config.ml"; "config.dune"]
     (list_files "app");
   Alcotest.(check files) "other files should be created in custom_build_"
     ["main.ml"; "app.ml"; "config.dune"; ".mirage.config"; "dune"; "key_gen.ml";