feat(melange): add manifest information for melange.emit

otherlibs/chrome-trace/src/chrome_trace.mli

@@ -11,7 +11,7 @@
     https://docs.google.com/document/d/1CvAClvFfyA5R-PhYUmn5OOQtYMH4h6I0nSsKchNAySU/preview *)
 
 module Json : sig
-  (** Simplifies JSON type *)
+  (** Simplified JSON type *)
   type t =
     [ `Int of int
     | `Float of float

src/dune_rules/melange/melange_rules.ml

@@ -1,5 +1,6 @@
 open Import
 open Memo.O
+module Json = Dune_stats.Json
 
 let output_of_lib =
   let public_lib ~info ~target_dir lib_name =
@@ -105,6 +106,107 @@ let impl_only_modules_defined_in_this_lib ~sctx ~scope lib =
       |> List.filter ~f:(Module.has ~ml_kind:Impl) )
 ;;
 
+let modules_for_js_and_obj_dir ~sctx ~dir_contents ~scope (mel : Melange_stanzas.Emit.t) =
+  let* modules, obj_dir =
+    Dir_contents.ocaml dir_contents
+    >>= Ml_sources.modules_and_obj_dir
+          ~libs:(Scope.libs scope)
+          ~for_:(Melange { target = mel.target })
+  in
+  let+ modules = modules_in_obj_dir ~sctx ~scope ~preprocess:mel.preprocess modules in
+  let modules_for_js =
+    Modules.fold modules ~init:[] ~f:(fun x acc ->
+      if Module.has x ~ml_kind:Impl then x :: acc else acc)
+  in
+  modules, modules_for_js, obj_dir
+;;
+
+(* attach [deps] to the specified [alias] AND the (dune default) [all] alias.
+
+   when [alias] is not supplied, {!Melange_stanzas.Emit.implicit_alias} is
+   assumed. *)
+let add_deps_to_aliases ?(alias = Melange_stanzas.Emit.implicit_alias) ~dir deps =
+  let alias = Alias.make alias ~dir in
+  let dune_default_alias = Alias.make Alias0.all ~dir in
+  let attach alias = Rules.Produce.Alias.add_deps alias deps in
+  Memo.parallel_iter ~f:attach [ alias; dune_default_alias ]
+;;
+
+module Manifest = struct
+  type mapping =
+    { source : Module.File.t
+    ; targets : Path.Build.t list
+    }
+
+  type t = { mappings : mapping list }
+
+  let sexp_of_mapping { source; targets } =
+    let source_str = Module.File.original_path source |> Path.to_string in
+    let target_strs = List.map targets ~f:Path.Build.to_string in
+    `Assoc [ source_str, `List (List.map target_strs ~f:(fun s -> `String s)) ]
+  ;;
+
+  let json_of_t t = `List (List.map t.mappings ~f:sexp_of_mapping)
+  let to_string t = Json.to_string (json_of_t t)
+
+  let create_mapping ~module_systems ~output modules =
+    let source = Module.source modules ~ml_kind:Impl |> Option.value_exn in
+    let targets =
+      List.map module_systems ~f:(fun (_, js_ext) -> make_js_name ~js_ext ~output modules)
+    in
+    { source; targets }
+  ;;
+
+  let setup_manifest_rule
+    ~sctx
+    ~target_dir
+    ~mode
+    ~module_systems
+    ~output
+    ~dir_contents
+    ~requires_link
+    ~scope
+    mel
+    =
+    let* _local_modules, modules_for_js, _local_obj_dir =
+      modules_for_js_and_obj_dir ~sctx ~dir_contents ~scope mel
+    in
+    let mappings_for_js =
+      List.map modules_for_js ~f:(fun modules ->
+        create_mapping ~module_systems ~output modules)
+    in
+    (* Get mappings for each required library *)
+    let* mappings_for_libs =
+      Memo.List.concat_map requires_link ~f:(fun lib ->
+        let* _modules_with_vlib, impl_modules =
+          impl_only_modules_defined_in_this_lib ~sctx ~scope lib
+        in
+        let lib_output = output_of_lib ~target_dir lib in
+        Memo.return
+          (List.map impl_modules ~f:(fun m ->
+             create_mapping ~module_systems ~output:lib_output m)))
+    in
+    let mappings = mappings_for_js @ mappings_for_libs in
+    let manifest_path = Path.Build.relative target_dir "melange-manifest.sexp" in
+    (* Format.eprintf "Creating manifest rule@."; *)
+    (* Format.eprintf "  dir: %s@." (Path.Build.to_string dir); *)
+    (* Format.eprintf "  target_dir: %s@." (Path.Build.to_string target_dir); *)
+    (* Format.eprintf "  mappings count: %d@." (List.length mappings); *)
+    (* Format.eprintf "  manifest path: %s@." (Path.Build.to_string manifest_path); *)
+    let manifest = { mappings } in
+    let manifest_str = to_string manifest in
+    (* Format.eprintf "  manifest content:@.%s@." manifest_str; *)
+    let* () =
+      Action_builder.return manifest_str
+      |> Action_builder.write_file_dyn manifest_path
+      |> Super_context.add_rule sctx ~dir:target_dir ~mode
+    in
+    let manifest_dep = Action_builder.path (Path.build manifest_path) in
+    let* () = add_deps_to_aliases ~dir:target_dir manifest_dep in
+    Memo.return ()
+  ;;
+end
+
 let cmj_glob = Glob.of_string_exn Loc.none "*.cmj"
 
 let cmj_includes ~(requires_link : Lib.t list Resolve.t) ~scope lib_config =
@@ -250,17 +352,6 @@ let build_js
     Super_context.add_rule sctx ~dir ~loc ~mode build)
 ;;
 
-(* attach [deps] to the specified [alias] AND the (dune default) [all] alias.
-
-   when [alias] is not supplied, {!Melange_stanzas.Emit.implicit_alias} is
-   assumed. *)
-let add_deps_to_aliases ?(alias = Melange_stanzas.Emit.implicit_alias) ~dir deps =
-  let alias = Alias.make alias ~dir in
-  let dune_default_alias = Alias.make Alias0.all ~dir in
-  let attach alias = Rules.Produce.Alias.add_deps alias deps in
-  Memo.parallel_iter ~f:attach [ alias; dune_default_alias ]
-;;
-
 let melange_compile_flags ~sctx ~dir (mel : Melange_stanzas.Emit.t) =
   let specific = Lib_mode.Map.make_all mel.compile_flags in
   Ocaml_flags.Spec.make ~common:Ordered_set_lang.Unexpanded.standard ~specific
@@ -439,21 +530,6 @@ let setup_runtime_assets_rules sctx ~dir ~target_dir ~mode ~output ~for_ mel =
   ()
 ;;
 
-let modules_for_js_and_obj_dir ~sctx ~dir_contents ~scope (mel : Melange_stanzas.Emit.t) =
-  let* modules, obj_dir =
-    Dir_contents.ocaml dir_contents
-    >>= Ml_sources.modules_and_obj_dir
-          ~libs:(Scope.libs scope)
-          ~for_:(Melange { target = mel.target })
-  in
-  let+ modules = modules_in_obj_dir ~sctx ~scope ~preprocess:mel.preprocess modules in
-  let modules_for_js =
-    Modules.fold modules ~init:[] ~f:(fun x acc ->
-      if Module.has x ~ml_kind:Impl then x :: acc else acc)
-  in
-  modules, modules_for_js, obj_dir
-;;
-
 let setup_entries_js
   ~sctx
   ~dir
@@ -470,6 +546,7 @@ let setup_entries_js
   let pkg_name = Option.map mel.package ~f:Package.name in
   let loc = mel.loc in
   let module_systems = mel.module_systems in
+  let* requires_link = Memo.Lazy.force requires_link in
   let* includes =
     let+ lib_config =
       let+ ocaml = Super_context.context sctx |> Context.ocaml in
@@ -632,6 +709,20 @@ let setup_js_rules_libraries_and_entries
     setup_js_rules_libraries ~dir ~scope ~target_dir ~sctx ~requires_link ~mode mel
   and+ () =
     setup_entries_js ~sctx ~dir ~dir_contents ~scope ~requires_link ~target_dir ~mode mel
+  and+ () =
+    match mel.emit_manifest with
+    | true ->
+      Manifest.setup_manifest_rule
+        ~sctx
+        ~target_dir
+        ~mode
+        ~module_systems:mel.module_systems
+        ~output:(`Private_library_or_emit target_dir)
+        ~dir_contents
+        ~scope
+        ~requires_link
+        mel
+    | false -> Memo.return ()
   in
   ()
 ;;

src/dune_rules/melange/melange_stanzas.ml

@@ -9,6 +9,7 @@ module Emit = struct
     ; module_systems : (Melange.Module_system.t * Filename.Extension.t) list
     ; modules : Stanza_common.Modules_settings.t
     ; emit_stdlib : bool
+    ; emit_manifest : bool
     ; libraries : Lib_dep.t list
     ; package : Package.t option
     ; preprocess : Preprocess.With_instrumentation.t Preprocess.Per_module.t
@@ -114,6 +115,7 @@ module Emit = struct
        and+ compile_flags = Ordered_set_lang.Unexpanded.field "compile_flags"
        and+ allow_overlapping_dependencies = field_b "allow_overlapping_dependencies"
        and+ emit_stdlib = field "emit_stdlib" bool ~default:true
+       and+ emit_manifest = field "emit_manifest" bool ~default:false
        and+ modules = Stanza_common.Modules_settings.decode
        and+ enabled_if =
          let open Enabled_if in
@@ -133,6 +135,7 @@ module Emit = struct
        ; module_systems
        ; modules
        ; emit_stdlib
+       ; emit_manifest
        ; libraries
        ; package
        ; preprocess

src/dune_rules/melange/melange_stanzas.mli

@@ -9,6 +9,7 @@ module Emit : sig
     ; module_systems : (Melange.Module_system.t * string) list
     ; modules : Stanza_common.Modules_settings.t
     ; emit_stdlib : bool
+    ; emit_manifest : bool
     ; libraries : Lib_dep.t list
     ; package : Package.t option
     ; preprocess : Preprocess.With_instrumentation.t Preprocess.Per_module.t

test/blackbox-tests/test-cases/melange/dune

@@ -4,7 +4,7 @@
    (DUNE_SANDBOX symlink))))
 
 (cram
- (deps %{bin:node} %{bin:melc})
+ (deps %{bin:node} %{bin:melc} %{bin:refmt})
  (alias runtest-melange))
 
 (cram

test/blackbox-tests/test-cases/melange/manifest.t

@@ -0,0 +1,56 @@
+Test melange manifest
+
+  $ cat > dune-project <<EOF
+  > (lang dune 3.8)
+  > (using melange 0.1)
+  > EOF
+
+  $ cat > dune <<EOF
+  > (melange.emit
+  >  (target output)
+  >  (emit_manifest true)
+  >  (modules main))
+  > EOF
+
+  $ cat > main.ml <<EOF
+  > Js.log "hello"
+  > EOF
+
+  $ dune build @melange
+  Creating manifest rule
+    dir: _build/default
+    target_dir: _build/default/output
+    mappings count: 1
+    manifest path: _build/default/output/melange-manifest.sexp
+    manifest content:
+  [{"_build/default/main.ml":["_build/default/output/main.js"]}]
+
+  $ ls _build/default/output
+  main.js
+  melange-manifest.sexp
+  node_modules
+
+  $ cat _build/default/output/melange-manifest.sexp
+  [{"_build/default/main.ml":["_build/default/output/main.js"]}]
+
+  $ dune rules @melange | grep -C 3 "manifest"
+  Creating manifest rule
+    dir: _build/default
+    target_dir: _build/default/output
+    mappings count: 1
+    manifest path: _build/default/output/melange-manifest.sexp
+    manifest content:
+  [{"_build/default/main.ml":["_build/default/output/main.js"]}]
+
+  ((deps ())
+   (targets
+    ((files (_build/default/output/melange-manifest.sexp)) (directories ())))
+   (context default)
+   (action
+    (chdir
+     _build/default
+     (write-file
+      output/melange-manifest.sexp
+      "[{\"_build/default/main.ml\":[\"_build/default/output/main.js\"]}]"))))
+
+  ((deps

test/blackbox-tests/test-cases/melange/manifest_with_re.t

@@ -0,0 +1,57 @@
+Test melange manifest
+
+  $ cat > dune-project <<EOF
+  > (lang dune 3.8)
+  > (using melange 0.1)
+  > EOF
+
+  $ cat > dune <<EOF
+  > (melange.emit
+  >  (target output)
+  >  (emit_manifest true)
+  >  (modules main))
+  > EOF
+
+
+  $ cat > main.re <<EOF
+  > Js.log "hello"
+  > EOF
+
+  $ dune build @melange
+  Creating manifest rule
+    dir: _build/default
+    target_dir: _build/default/output
+    mappings count: 1
+    manifest path: _build/default/output/melange-manifest.sexp
+    manifest content:
+  [{"_build/default/main.re":["_build/default/output/main.js"]}]
+
+  $ ls _build/default/output
+  main.js
+  melange-manifest.sexp
+  node_modules
+
+  $ cat _build/default/output/melange-manifest.sexp
+  [{"_build/default/main.re":["_build/default/output/main.js"]}]
+
+  $ dune rules @melange | grep -C 3 "manifest"
+  Creating manifest rule
+    dir: _build/default
+    target_dir: _build/default/output
+    mappings count: 1
+    manifest path: _build/default/output/melange-manifest.sexp
+    manifest content:
+  [{"_build/default/main.re":["_build/default/output/main.js"]}]
+
+  ((deps ())
+   (targets
+    ((files (_build/default/output/melange-manifest.sexp)) (directories ())))
+   (context default)
+   (action
+    (chdir
+     _build/default
+     (write-file
+      output/melange-manifest.sexp
+      "[{\"_build/default/main.re\":[\"_build/default/output/main.js\"]}]"))))
+
+  ((deps