Extend explicit_js_mode to libraries

Signed-off-by: Nicolás Ojeda Bär <n.oje.bar@gmail.com>

src/binary_kind.ml

@@ -5,7 +5,6 @@ type t =
   | Exe
   | Object
   | Shared_object
-  | Js
 
 let decode =
   let open Dune_lang.Decoder in
@@ -14,20 +13,18 @@ let decode =
     ; "exe"           , return Exe
     ; "object"        , return Object
     ; "shared_object" , return Shared_object
-    ; "js"            , Syntax.since Stanza.syntax (1, 9) >>> return Js
     ]
 
 let to_string = function
   | C -> "c"
   | Exe -> "exe"
   | Object -> "object"
   | Shared_object -> "shared_object"
-  | Js -> "js"
 
 let pp fmt t =
   Format.pp_print_string fmt (to_string t)
 
 let encode t =
   Dune_lang.unsafe_atom_of_string (to_string t)
 
-let all = [C; Exe; Object; Shared_object; Js]
+let all = [C; Exe; Object; Shared_object]

src/binary_kind.mli

@@ -7,7 +7,6 @@ type t =
   | Exe
   | Object
   | Shared_object
-  | Js
 
 include Dune_lang.Conv with type t := t
 

src/dune_file.ml

@@ -745,6 +745,7 @@ module Mode_conf = struct
       | Byte
       | Native
       | Best
+      | Js
     let compare (a : t) b = compare a b
   end
   include T
@@ -754,12 +755,14 @@ module Mode_conf = struct
       [ "byte"  , Byte
       ; "native", Native
       ; "best"  , Best
+      ; "js"    , Js
       ]
 
   let to_string = function
     | Byte -> "byte"
     | Native -> "native"
     | Best -> "best"
+    | Js -> "js"
 
   let pp fmt t =
     Format.pp_print_string fmt (to_string t)
@@ -776,7 +779,7 @@ module Mode_conf = struct
 
     let eval t ~has_native =
       let has_best = mem t Best in
-      let byte = mem t Byte || (has_best && (not has_native)) in
+      let byte = mem t Js || mem t Byte || (has_best && (not has_native)) in
       let native = has_native && (mem t Native || has_best) in
       { Mode.Dict.byte; native }
   end
@@ -1309,7 +1312,7 @@ module Executables = struct
     let shared_object = make Best Shared_object
 
     let byte_exe           = make Byte Exe
-    let byte_js            = make Byte Js
+    let js                 = make Js Exe
 
     let native_exe           = make Native Exe
     let native_object        = make Native Object
@@ -1327,7 +1330,7 @@ module Executables = struct
       ; "shared_object" , shared_object
       ; "byte"          , byte
       ; "native"        , native
-      ; "js"            , byte_js
+      ; "js"            , js
       ]
 
     let simple =
@@ -1449,6 +1452,7 @@ module Executables = struct
             match mode.mode with
             | Native | Best -> ".exe"
             | Byte -> ".bc"
+            | Js -> ".bc.js"
           in
           Names.install_conf names ~ext
       in

src/dune_file.mli

@@ -154,6 +154,7 @@ module Mode_conf : sig
     | Byte
     | Native
     | Best (** [Native] if available and [Byte] if not *)
+    | Js
 
   val decode : t Dune_lang.Decoder.t
   val compare : t -> t -> Ordering.t
@@ -273,7 +274,7 @@ module Executables : sig
     val object_       : t
     val shared_object : t
     val byte          : t
-    val byte_js       : t
+    val js            : t
     val native        : t
 
     val compare : t -> t -> Ordering.t

src/exe.ml

@@ -60,25 +60,25 @@ module Linkage = struct
       | Byte   -> Byte
       | Native -> Native
       | Best   -> Native
+      | Js     -> Byte
     in
     let real_mode : Mode.t =
       match m.mode with
       | Byte   -> Byte
       | Native -> Native
       | Best   -> if Option.is_some ctx.ocamlopt then Native else Byte
+      | Js     -> Byte
     in
     let ext =
       match wanted_mode, m.kind with
       | Byte   , C             -> ".bc.c"
       | Native , C             -> Errors.fail m.loc "C file generation only supports bytecode!"
-      | Byte   , Exe           -> ".bc"
+      | Byte   , Exe           -> if m.mode = Js then ".bc.js" else ".bc"
       | Native , Exe           -> ".exe"
       | Byte   , Object        -> ".bc"  ^ ctx.ext_obj
       | Native , Object        -> ".exe" ^ ctx.ext_obj
       | Byte   , Shared_object -> ".bc"  ^ ctx.ext_dll
       | Native , Shared_object ->          ctx.ext_dll
-      | Byte   , Js            -> ".bc.js"
-      | Native , Js            -> Errors.fail m.loc "Javascript generation only supports bytecode!"
     in
     let flags =
       match m.kind with
@@ -107,7 +107,6 @@ module Linkage = struct
         | Byte ->
           so_flags
         end
-      | Js -> []
     in
     { ext
     ; mode = real_mode

src/exe_rules.ml

@@ -47,14 +47,14 @@ let executables_rules ~sctx ~dir ~dir_kind ~expander
                   Module.Name.pp mod_name)
   in
 
-  let has_js = Dune_file.Executables.Link_mode.(Set.mem exes.modes byte_js) in
+  let has_js = Dune_file.Executables.Link_mode.(Set.mem exes.modes js) in
 
   let linkages =
     let module L = Dune_file.Executables.Link_mode in
     let ctx = SC.context sctx in
     let modes =
       if has_js then
-        L.Set.remove (L.Set.add exes.modes L.byte) L.byte_js
+        L.Set.remove (L.Set.add exes.modes L.byte) L.js
       else
         exes.modes
     in

src/lib_rules.ml

@@ -338,6 +338,7 @@ module Gen (P : sig val sctx : Super_context.t end) = struct
     let modules = Compilation_context.modules cctx in
     let js_of_ocaml = lib.buildable.js_of_ocaml in
     let vimpl = Compilation_context.vimpl cctx in
+    let explicit_js_mode = Dune_project.explicit_js_mode (Scope.project (Compilation_context.scope cctx)) in
     let modules =
       match lib.stdlib with
       | Some { exit_module = Some name; _ } -> begin
@@ -387,7 +388,7 @@ module Gen (P : sig val sctx : Super_context.t end) = struct
        build_lib lib ~expander ~flags ~dir ~mode ~top_sorted_modules
          ~modules));
     (* Build *.cma.js *)
-    if modes.byte then
+    if Mode_conf.(Set.mem lib.modes Js) || (not explicit_js_mode && modes.byte) then
       SC.add_rules sctx ~dir (
         let src =
           Library.archive lib ~dir