feature: dune show targets and dune show aliases

Add a `dune show targets` and `dune show aliases` command for showing
targets and aliases in a directory like `ls`.

fix ocaml#265

Co-authored-by: Rudi Grinberg <me@rgrinberg.com>
Signed-off-by: Ali Caglayan <alizter@gmail.com>

CHANGES.md

@@ -48,6 +48,10 @@ Unreleased
 - Respect `-p` / `--only-packages` for `melange.emit` artifacts (#7849,
   @anmonteiro)
 
+- Add commands `dune show targets` and `dune show aliases`, which are similar to
+  `ls`, that display all the available targets and aliases in a given directory
+  respectively. (#7770, grants #265, @Alizter)
+
 - Fix scanning of Coq installed files (@ejgallego, reported by
   @palmskog, #7895 , fixes #7893)
 

bin/describe/aliases_cmd.ml

@@ -0,0 +1,30 @@
+open Import
+
+let fetch_results (build_system : Dune_rules.Main.build_system) root
+    (_dir : Path.t) =
+  let open Action_builder.O in
+  let+ alias_targets =
+    let+ load_dir =
+      Action_builder.List.map build_system.contexts ~f:(fun ctx ->
+          let dir =
+            Path.Build.append_source
+              (Dune_engine.Context_name.build_dir (Context.name ctx))
+              root
+            |> Path.build
+          in
+          Action_builder.of_memo (Load_rules.load_dir ~dir))
+    in
+    List.fold_left load_dir ~init:Dune_engine.Alias.Name.Map.empty
+      ~f:(fun acc x ->
+        match (x : Load_rules.Loaded.t) with
+        | Build build -> Dune_engine.Alias.Name.Map.superpose acc build.aliases
+        | _ -> acc)
+    |> Dune_engine.Alias.Name.Map.keys
+  in
+  List.map ~f:Dune_engine.Alias.Name.to_string alias_targets
+
+let term = Ls_like_cmd.term fetch_results
+
+let command =
+  let doc = "Print aliases in a given directory. Works similalry to ls." in
+  Cmd.v (Cmd.info "aliases" ~doc ~envs:Common.envs) term

bin/describe/aliases_cmd.mli

@@ -0,0 +1,5 @@
+open Import
+
+(** The aliases command lists all the aliases available in the given directory,
+    defaulting to the current working direcctory. *)
+val command : unit Cmd.t

bin/describe/describe.ml

@@ -13,6 +13,8 @@ let subcommands =
   ; Describe_opam_files.command
   ; Describe_pp.command
   ; Printenv.command
+  ; Targets_cmd.command
+  ; Aliases_cmd.command
   ]
 
 let group =

bin/describe/ls_like_cmd.ml

@@ -0,0 +1,34 @@
+open Import
+
+let term fetch_results =
+  let+ common = Common.term
+  and+ paths = Arg.(value & pos_all string [ "." ] & info [] ~docv:"DIR") in
+  let config = Common.init common in
+  let request (build_system : Dune_rules.Main.build_system) =
+    let header = List.length paths > 1 in
+    let open Action_builder.O in
+    let+ paragraphs =
+      Action_builder.List.map paths ~f:(fun path ->
+          let dir = Path.of_string path in
+          let root =
+            match (dir : Path.t) with
+            | External e ->
+              Code_error.raise "target_hint: external path"
+                [ ("path", Path.External.to_dyn e) ]
+            | In_source_tree d -> d
+            | In_build_dir d -> (
+              match Path.Build.drop_build_context d with
+              | Some d -> d
+              | None -> Path.Source.root)
+          in
+          let+ targets = fetch_results build_system root dir in
+          (if header then [ Pp.textf "%s:" (Path.to_string dir) ] else [])
+          @ [ Pp.concat_map targets ~f:Pp.text ~sep:Pp.newline ]
+          |> Pp.concat ~sep:Pp.newline)
+    in
+    Console.print [ Pp.concat paragraphs ~sep:(Pp.seq Pp.newline Pp.newline) ]
+  in
+  Scheduler.go ~common ~config @@ fun () ->
+  let open Fiber.O in
+  Build_cmd.run_build_system ~common ~request
+  >>| fun (_ : (unit, [ `Already_reported ]) result) -> ()

bin/describe/ls_like_cmd.mli

@@ -0,0 +1,8 @@
+open Import
+
+val term :
+     (   Dune_rules.Main.build_system
+      -> Path.Source.t
+      -> Path.t
+      -> string list Action_builder.t)
+  -> unit Term.t

bin/describe/targets_cmd.ml

@@ -0,0 +1,33 @@
+open Import
+
+let fetch_results (_ : Dune_rules.Main.build_system) root dir =
+  let open Action_builder.O in
+  let+ targets =
+    let open Memo.O in
+    Target.all_direct_targets (Some root)
+    >>| Path.Build.Map.to_list |> Action_builder.of_memo
+  in
+  List.map targets
+    ~f:
+      (if Path.is_in_build_dir dir then fun (path, k) -> (Path.build path, k)
+      else fun (path, k) ->
+        match Path.Build.extract_build_context path with
+        | None -> (Path.build path, k)
+        | Some (_, path) -> (Path.source path, k))
+  |> (* Only suggest hints for the basename, otherwise it's slow when there
+        are lots of files *)
+  List.filter_map ~f:(fun (path, kind) ->
+      match Path.equal (Path.parent_exn path) dir with
+      | false -> None
+      | true ->
+        (* directory targets can be distinguied by the trailing path seperator *)
+        Some
+          (match kind with
+          | Target.File -> Path.basename path
+          | Directory -> Path.basename path ^ Filename.dir_sep))
+
+let term = Ls_like_cmd.term fetch_results
+
+let command =
+  let doc = "Print targets in a given directory. Works similalry to ls." in
+  Cmd.v (Cmd.info "targets" ~doc ~envs:Common.envs) term

bin/describe/targets_cmd.mli

@@ -0,0 +1,5 @@
+open Import
+
+(** The targets command lists all the targets available in the given directory,
+    defaulting to the current working direcctory. *)
+val command : unit Cmd.t

test/blackbox-tests/test-cases/describe/aliases.t/dune-project

@@ -0,0 +1 @@
+(lang dune 3.8)

test/blackbox-tests/test-cases/describe/aliases.t/run.t

@@ -0,0 +1,107 @@
+Testing the "dune show aliases" command. This command shows the aliases in the
+current directory. It acts similarly to ls. It will not show aliases that appear
+in subdirectories although this could be changed in the future.
+
+In an empty dune project, the following aliases are available.
+
+  $ dune show aliases
+  all
+  default
+  fmt
+
+User defined aliases can be added to a dune file. These should be picked up by
+the command.
+
+  $ cat > dune << EOF
+  > (alias
+  >  (name foo))
+  > EOF
+
+  $ dune show aliases
+  all
+  default
+  fmt
+  foo
+
+Aliases in subdirectories should not be picked up.
+
+  $ mkdir subdir
+  $ cat > subdir/dune << EOF
+  > (alias
+  >  (name bar))
+  > EOF
+
+  $ dune show aliases
+  all
+  default
+  fmt
+  foo
+
+But checking the subdirectory it should be available.
+
+  $ dune show aliases subdir
+  all
+  bar
+  default
+  fmt
+
+Adding an OCaml library will introduce OCaml specific aliases:
+
+  $ cat > dune << EOF
+  > (library
+  >  (name foo))
+  > EOF
+
+  $ dune show aliases
+  all
+  check
+  default
+  doc-private
+  fmt
+
+Adding a cram test will introduce an alias with the name of the test and also
+introduce the runtest alias:
+bbb
+  $ rm dune
+  $ cat > mytest.t
+
+  $ dune show aliases
+  all
+  default
+  fmt
+  mytest
+  runtest
+
+We can also show aliases in multiple directories at once:
+
+  $ dune show aliases . subdir
+  .:
+  all
+  default
+  fmt
+  mytest
+  runtest
+  
+  subdir:
+  all
+  bar
+  default
+  fmt
+
+Including those in the _build/ directory:
+
+  $ dune build
+  $ dune show aliases . _build/default
+  .:
+  all
+  default
+  fmt
+  mytest
+  runtest
+  
+  _build/default:
+  all
+  default
+  fmt
+  mytest
+  runtest

test/blackbox-tests/test-cases/describe/targets.t/b/dune

@@ -0,0 +1,2 @@
+(library
+ (name simple2))

test/blackbox-tests/test-cases/describe/targets.t/dune

@@ -0,0 +1,10 @@
+(library
+ (name simple))
+
+(rule
+ (targets
+  (dir d))
+ (action
+  (progn
+   (run mkdir d)
+   (run cat > d/foo))))

test/blackbox-tests/test-cases/describe/targets.t/dune-project

@@ -0,0 +1,2 @@
+(lang dune 3.8)
+(using directory-targets 0.1)

test/blackbox-tests/test-cases/describe/targets.t/run.t

@@ -0,0 +1,69 @@
+Testing the "dune show targets" command in a simple OCaml project with an
+additional directory target to see the behaviour there.
+
+We have two libraries with one in a subdirectory. We also have a directory
+target d to see how the command will behave.
+
+With no directory provided to the command, it should default to the current
+working directory.
+
+  $ dune show targets
+  a.ml
+  d/
+  dune
+  dune-project
+  simple.a
+  simple.cma
+  simple.cmxa
+  simple.cmxs
+  simple.ml-gen
+
+Multiple directories can be provided to the command. Also subdirectories may be
+used, and only the targets available in that directory will be displayed.
+
+  $ dune show targets . b/
+  .:
+  a.ml
+  d/
+  dune
+  dune-project
+  simple.a
+  simple.cma
+  simple.cmxa
+  simple.cmxs
+  simple.ml-gen
+
+  b:
+  c.ml
+  dune
+  simple2.a
+  simple2.cma
+  simple2.cmxa
+  simple2.cmxs
+  simple2.ml-gen
+
+The command also works with files in the _build directory.
+
+  $ dune show targets _build/default/
+  a.ml
+  d/
+  dune
+  dune-project
+  simple.a
+  simple.cma
+  simple.cmxa
+  simple.cmxs
+  simple.ml-gen
+
+  $ dune show targets _build/default/b
+  c.ml
+  dune
+  simple2.a
+  simple2.cma
+  simple2.cmxa
+  simple2.cmxs
+  simple2.ml-gen
+We cannot see inside directory targets
+
+  $ dune show targets d
+