fix(melange): add melange module compilation as part of @all alias (#12628)

* fix(melange): add melange module compilation as part of `@all` alias

Signed-off-by: Antonio Nuno Monteiro <anmonteiro@gmail.com>

* fix: tests

Signed-off-by: Antonio Nuno Monteiro <anmonteiro@gmail.com>

* add changelog entry

Signed-off-by: Antonio Nuno Monteiro <anmonteiro@gmail.com>

---------

Signed-off-by: Antonio Nuno Monteiro <anmonteiro@gmail.com>

Author: anmonteiro

doc/changes/fixed/12628.md

@@ -0,0 +1,2 @@
+- Add Melange compilation to the `@all` alias in libraries (#12628,
+  @anmonteiro)

src/dune_rules/alias_builder.ml

@@ -1,5 +1,4 @@
 open Import
-open Action_builder
 
 module Alias_status = struct
   module T = struct
@@ -21,7 +20,7 @@ module Alias_status = struct
   include Monoid.Make (T)
 end
 
-let alias a = dep (Dep.alias a)
+let alias a = Action_builder.dep (Dep.alias a)
 
 module Alias_build_info = struct
   type t =
@@ -40,7 +39,7 @@ module Alias_build_info = struct
 end
 
 let dep_on_alias_build_info_if_exists alias =
-  let open O in
+  let open Action_builder.O in
   Load_rules.load_dir ~dir:(Path.build (Alias.dir alias))
   |> Action_builder.of_memo
   >>= function
@@ -62,8 +61,8 @@ let dep_on_alias_build_info_if_exists alias =
 module Alias_rec (Traverse : sig
     val traverse
       :  Path.Build.t
-      -> f:(path:Path.Build.t -> Alias_build_info.t t)
-      -> Alias_status.t t
+      -> f:(path:Path.Build.t -> Alias_build_info.t Action_builder.t)
+      -> Alias_status.t Action_builder.t
   end) =
 struct
   open Traverse
@@ -73,3 +72,23 @@ struct
     traverse dir ~f
   ;;
 end
+
+let define_all_alias ?predicate_dir ~project ~js_targets dir =
+  let deps =
+    let predicate =
+      if Dune_project.explicit_js_mode project
+      then Predicate_lang.true_
+      else (
+        List.iter js_targets ~f:(fun js_target ->
+          assert (Path.Build.equal (Path.Build.parent_exn js_target) dir));
+        Predicate_lang.not
+          (Predicate_lang.Glob.of_string_set
+             (String.Set.of_list_map js_targets ~f:Path.Build.basename)))
+    in
+    let only_generated_files = Dune_project.dune_version project >= (3, 0) in
+    let dir = Option.value predicate_dir ~default:dir in
+    File_selector.of_predicate_lang ~dir:(Path.build dir) ~only_generated_files predicate
+    |> Action_builder.paths_matching_unit ~loc:Loc.none
+  in
+  Rules.Produce.Alias.add_deps (Alias.make Alias0.all ~dir) deps
+;;

src/dune_rules/alias_builder.mli

@@ -38,3 +38,10 @@ module Alias_rec (_ : sig
       in at least one directory, and [Not_defined] otherwise. *)
   val dep_on_alias_rec : Alias.Name.t -> Path.Build.t -> Alias_status.t Action_builder.t
 end
+
+val define_all_alias
+  :  ?predicate_dir:Path.Build.t
+  -> project:Dune_project.t
+  -> js_targets:Path.Build.t list
+  -> Path.Build.t
+  -> unit Memo.t

src/dune_rules/gen_rules.ml

@@ -192,25 +192,6 @@ end = struct
   ;;
 end
 
-let define_all_alias ~dir ~project ~js_targets =
-  let deps =
-    let predicate =
-      if Dune_project.explicit_js_mode project
-      then Predicate_lang.true_
-      else (
-        List.iter js_targets ~f:(fun js_target ->
-          assert (Path.Build.equal (Path.Build.parent_exn js_target) dir));
-        Predicate_lang.not
-          (Predicate_lang.Glob.of_string_set
-             (String.Set.of_list_map js_targets ~f:Path.Build.basename)))
-    in
-    let only_generated_files = Dune_project.dune_version project >= (3, 0) in
-    File_selector.of_predicate_lang ~dir:(Path.build dir) ~only_generated_files predicate
-    |> Action_builder.paths_matching_unit ~loc:Loc.none
-  in
-  Rules.Produce.Alias.add_deps (Alias.make Alias0.all ~dir) deps
-;;
-
 let gen_rules_for_stanzas sctx dir_contents cctxs expander ~dune_file ~dir:ctx_dir =
   let src_dir = Dune_file.dir dune_file in
   let* stanzas = Dune_file.stanzas dune_file
@@ -295,7 +276,7 @@ let gen_rules_for_stanzas sctx dir_contents cctxs expander ~dune_file ~dir:ctx_d
       | _ -> Memo.return ())
   and+ () =
     let project = Dune_file.project dune_file in
-    define_all_alias ~dir:ctx_dir ~project ~js_targets
+    Alias_builder.define_all_alias ~project ~js_targets ctx_dir
   in
   cctxs
 ;;
@@ -311,7 +292,10 @@ let gen_rules_source_only sctx ~dir source_dir =
     let* sctx = sctx in
     let+ () = gen_format_and_cram_rules sctx ~dir source_dir
     and+ () =
-      define_all_alias ~dir ~js_targets:[] ~project:(Source_tree.Dir.project source_dir)
+      Alias_builder.define_all_alias
+        ~js_targets:[]
+        ~project:(Source_tree.Dir.project source_dir)
+        dir
     in
     ())
 ;;
@@ -329,7 +313,7 @@ let gen_rules_group_part_or_root sctx dir_contents cctxs ~source_dir ~dir
       >>= gen_rules_for_stanzas sctx dir_contents cctxs ~dune_file ~dir
     | None ->
       let project = Source_tree.Dir.project source_dir in
-      let+ () = define_all_alias ~dir ~js_targets:[] ~project in
+      let+ () = Alias_builder.define_all_alias ~js_targets:[] ~project dir in
       []
   in
   contexts

src/dune_rules/module_compilation.ml

@@ -383,12 +383,18 @@ let build_module ?(force_write_cmi = false) ?(precompiled_cmi = false) cctx m =
             Super_context.add_rule sctx ~dir action_with_targets)))
   in
   Memo.when_ melange (fun () ->
-    let+ () = build_cm ~cm_kind:(Melange Cmj) ~phase:None
-    and+ () =
+    let* () = build_cm ~cm_kind:(Melange Cmj) ~phase:None
+    and* () =
       Memo.when_ (not precompiled_cmi) (fun () ->
         build_cm ~cm_kind:(Melange Cmi) ~phase:None)
     in
-    ())
+    let project = Compilation_context.scope cctx |> Scope.project in
+    let dir = Compilation_context.dir cctx in
+    let predicate_dir =
+      let obj_dir = Compilation_context.obj_dir cctx in
+      Obj_dir.melange_dir obj_dir
+    in
+    Alias_builder.define_all_alias ~project ~predicate_dir ~js_targets:[] dir)
 ;;
 
 let ocamlc_i ~deps cctx (m : Module.t) ~output =

test/blackbox-tests/test-cases/melange/dune-rules.t

@@ -19,6 +19,7 @@ Test dune rules
 Calling dune rules with the 'all' alias works fine
 
   $ dune rules @all | grep In_build_dir
+     (File (In_build_dir _build/default/main.ml))))
       (In_build_dir _build/default/.output.mobjs/melange/melange__Main.cmj))))
 
 Calling dune rules with the alias works fine

test/blackbox-tests/test-cases/melange/melange-alias-all.t

@@ -16,5 +16,10 @@ Melange compilation is added to `@all`
   > EOF
 
   $ dune build @all
-  $ find _build/default | grep '\.cm'
-  [1]
+  $ find _build/default | grep '\.cm' | sort
+  _build/default/lib/.mlib.objs/melange/mlib.cmi
+  _build/default/lib/.mlib.objs/melange/mlib.cmj
+  _build/default/lib/.mlib.objs/melange/mlib.cmt
+  _build/default/lib/.mlib.objs/melange/mlib__Hello.cmi
+  _build/default/lib/.mlib.objs/melange/mlib__Hello.cmj
+  _build/default/lib/.mlib.objs/melange/mlib__Hello.cmt

test/blackbox-tests/test-cases/melange/transitive-ppx.t

@@ -34,7 +34,7 @@ Test interaction of melange.emit library ppx dependencies
                         ^^^^^^^^^^^
   Error: Library "not-present" not found.
   -> required by library "mel-subdir" in _build/default/lib/impl
-  -> required by melange target dist
-  -> required by alias lib/test/all
+  -> required by _build/default/META.mel-subdir
+  -> required by alias all
   -> required by alias default
   [1]