Drop code duplication, simplify API

Signed-off-by: Andrey Mokhov <amokhov@janestreet.com>

src/dune/dune_file.ml

@@ -958,33 +958,22 @@ module Library = struct
     List.is_non_empty t.buildable.foreign_stubs
     || List.is_non_empty t.buildable.foreign_archives
 
-  let default_archive_name t = Lib_name.Local.to_string (snd t.name) ^ "_stubs"
-
-  let default_lib_file t ~dir ~ext_lib =
-    Path.Build.relative dir
-      (sprintf "lib%s%s" (default_archive_name t) ext_lib)
-
-  let default_dll_file t ~dir ~ext_dll =
-    Path.Build.relative dir
-      (sprintf "dll%s%s" (default_archive_name t) ext_dll)
+  let stubs_archive_name t = Lib_name.Local.to_string (snd t.name) ^ "_stubs"
 
   let archive_names t =
     ( if List.is_empty t.buildable.foreign_stubs then
       []
     else
-      [ default_archive_name t ] )
+      [ stubs_archive_name t ] )
     @ List.map ~f:snd t.buildable.foreign_archives
 
-  (* TODO_AM: Code duplication. *)
   let lib_files t ~dir ~ext_lib =
-    List.map (archive_names t) ~f:(fun name ->
-        Path.Build.relative dir (sprintf "lib%s%s" name ext_lib))
+    List.map (archive_names t) ~f:(fun archive_name ->
+        Foreign.lib_file ~archive_name ~dir ~ext_lib)
 
   let dll_files t ~dir ~ext_dll =
-    List.map (archive_names t) ~f:(fun name ->
-        Path.Build.relative dir (sprintf "dll%s%s" name ext_dll))
-
-  let stubs_path t ~dir = Path.Build.relative dir (default_archive_name t)
+    List.map (archive_names t) ~f:(fun archive_name ->
+        Foreign.dll_file ~archive_name ~dir ~ext_dll)
 
   let archive t ~dir ~ext =
     Path.Build.relative dir (Lib_name.Local.to_string (snd t.name) ^ ext)

src/dune/dune_file.mli

@@ -202,22 +202,14 @@ module Library : sig
 
   val has_stubs : t -> bool
 
-  val default_archive_name : t -> string
-
-  val default_lib_file :
-    t -> dir:Path.Build.t -> ext_lib:string -> Path.Build.t
-
-  val default_dll_file :
-    t -> dir:Path.Build.t -> ext_dll:string -> Path.Build.t
+  val stubs_archive_name : t -> string
 
   val archive_names : t -> string list
 
   val lib_files : t -> dir:Path.Build.t -> ext_lib:string -> Path.Build.t list
 
   val dll_files : t -> dir:Path.Build.t -> ext_dll:string -> Path.Build.t list
 
-  val stubs_path : t -> dir:Path.Build.t -> Path.Build.t
-
   val archive : t -> dir:Path.Build.t -> ext:string -> Path.Build.t
 
   val best_name : t -> Lib_name.t

src/dune/lib_rules.ml

@@ -136,10 +136,11 @@ let ocamlmklib ~path ~loc ~c_library_flags ~sctx ~dir ~expander ~o_files
 (* Add a rule calling [ocamlmklib] to build an OCaml library. *)
 let ocamlmklib_ocaml (lib : Library.t) ~sctx ~dir ~expander ~o_files ~sandbox
     ~custom ~targets =
-  ocamlmklib
-    ~path:(Path.build (Library.stubs_path lib ~dir))
-    ~loc:lib.buildable.loc ~c_library_flags:lib.c_library_flags ~sctx ~dir
-    ~expander ~o_files ~sandbox ~custom ~targets
+  let path =
+    Path.build (Path.Build.relative dir (Library.stubs_archive_name lib))
+  in
+  ocamlmklib ~path ~loc:lib.buildable.loc ~c_library_flags:lib.c_library_flags
+    ~sctx ~dir ~expander ~o_files ~sandbox ~custom ~targets
 
 (* Build a static and a dynamic archive for a foreign library. *)
 let build_foreign_library (library : Foreign.Library.t) ~sctx ~expander ~dir
@@ -226,8 +227,9 @@ let build_self_stubs lib ~cctx ~expander ~dir ~o_files =
   let sctx = Compilation_context.super_context cctx in
   let ctx = Super_context.context sctx in
   let { Lib_config.ext_lib; ext_dll; _ } = ctx.lib_config in
-  let static = Library.default_lib_file lib ~dir ~ext_lib in
-  let dynamic = Library.default_dll_file lib ~dir ~ext_dll in
+  let archive_name = Library.stubs_archive_name lib in
+  let static = Foreign.lib_file ~archive_name ~dir ~ext_lib in
+  let dynamic = Foreign.dll_file ~archive_name ~dir ~ext_dll in
   let modes = Compilation_context.modes cctx in
   let ocamlmklib = ocamlmklib_ocaml lib ~sctx ~expander ~dir ~o_files in
   if