WIP: Ocamlformat integration

src/dune_file.ml

@@ -680,6 +680,7 @@ module Buildable = struct
     ; ocamlopt_flags           : Ordered_set_lang.Unexpanded.t
     ; js_of_ocaml              : Js_of_ocaml.t
     ; allow_overlapping_dependencies : bool
+    ; ocamlformat : bool
     }
 
   let dparse =
@@ -700,6 +701,7 @@ module Buildable = struct
       field "js_of_ocaml" Js_of_ocaml.dparse ~default:Js_of_ocaml.default
     and allow_overlapping_dependencies =
       field_b "allow_overlapping_dependencies"
+    and ocamlformat = field_b "ocamlformat"
     in
     { loc
     ; preprocess
@@ -713,6 +715,7 @@ module Buildable = struct
     ; ocamlopt_flags
     ; js_of_ocaml
     ; allow_overlapping_dependencies
+    ; ocamlformat
     }
 
   let single_preprocess t =

src/dune_file.mli

@@ -141,6 +141,7 @@ module Buildable : sig
     ; ocamlopt_flags           : Ordered_set_lang.Unexpanded.t
     ; js_of_ocaml              : Js_of_ocaml.t
     ; allow_overlapping_dependencies : bool
+    ; ocamlformat : bool
     }
 
   (** Preprocessing specification used by all modules or [No_preprocessing] *)

src/lib_rules.ml

@@ -375,6 +375,7 @@ module Gen (P : Install_rules.Params) = struct
         ~lib_name:(Some lib.name)
         ~dir_kind
     in
+    Ocamlformat.gen_rules sctx lib.buildable ~dir ~scope modules;
     let modules = Preprocessing.pp_modules pp modules in
 
     let modules =

src/ocamlformat.ml

@@ -0,0 +1,72 @@
+open Import
+
+let flag_of_kind : Ml_kind.t -> _ =
+  function
+  | Impl -> "--impl"
+  | Intf -> "--intf"
+
+let add_alias_format sctx loc ~dir ~scope action =
+  let alias_conf =
+    { Dune_file.Alias_conf.name = "format"
+    ; deps = []
+    ; action = Some (loc, action)
+    ; locks = []
+    ; package = None
+    ; enabled_if = None
+    ; loc
+    }
+  in
+  Simple_rules.alias sctx ~dir ~scope alias_conf
+
+let sv = String_with_vars.virt_text __POS__
+
+let target_var = String_with_vars.virt_var __POS__ "targets"
+
+let gen_rules_for_module sctx loc ocamlformat ~dir ~scope m =
+  Format.printf "dir = %a\n" Path.pp dir;
+  Module.iter m ~f:(fun kind src ->
+    let flag = flag_of_kind kind in
+    let path = Path.basename src.path in
+    let dep x = String_with_vars.make_macro loc "dep" x in
+    let formatted = path ^ ".formatted" in
+    let format_action =
+      let args = [sv flag; dep path] in
+      Action.Unexpanded.Redirect
+        ( Stdout
+        , target_var
+        , Run (dep @@ Path.to_string ocamlformat, args)
+        )
+    in
+    let format_rule =
+      { Dune_file.Rule.targets = Static [formatted]
+      ; deps = []
+      ; action = (loc, format_action)
+      ; mode = Standard
+      ; locks = []
+      ; loc
+      }
+    in
+    let diff_action =
+      Action.Unexpanded.Diff
+        { optional = false
+        ; mode = Text
+        ; file1 = dep path
+        ; file2 = sv formatted
+        }
+    in
+    let _ : Path.t list = Simple_rules.user_rule sctx ~dir ~scope format_rule in
+    add_alias_format sctx loc ~dir ~scope diff_action
+  )
+
+let gen_rules sctx (buildable:Dune_file.Buildable.t)
+      ~dir ~scope modules =
+  if buildable.ocamlformat then
+    let loc = buildable.loc in
+    match Bin.which "ocamlformat" with
+    | None ->
+      let msg = "Cannot find ocamlformat, skipping.\n" in
+      add_alias_format sctx loc ~dir ~scope (Echo [sv msg])
+    | Some ocamlformat ->
+      Module.Name.Map.iter
+        modules
+        ~f:(gen_rules_for_module sctx loc ocamlformat ~dir ~scope)

src/ocamlformat.mli

@@ -0,0 +1,9 @@
+open Import
+
+val gen_rules :
+  Super_context.t
+  -> Dune_file.Buildable.t
+  -> dir:Path.t
+  -> scope:Scope.t
+  -> Module.t Module.Name.Map.t
+  -> unit

src/string_with_vars.ml

@@ -20,16 +20,22 @@ let make ?(quoted=false) loc part =
 let make_text ?quoted loc s =
   make ?quoted loc (Text s)
 
-let make_var ?quoted loc name =
+let make_var_args ?quoted loc name payload =
   let var =
     { loc
     ; name
-    ; payload = None
+    ; payload
     ; syntax = Percent
   }
   in
   make ?quoted loc (Var var)
 
+let make_var ?quoted loc name =
+  make_var_args ?quoted loc name None
+
+let make_macro ?quoted loc macro param =
+  make_var_args ?quoted loc macro (Some param)
+
 let literal ~quoted ~loc s =
   { parts = [Text s]
   ; quoted

src/string_with_vars.mli

@@ -27,6 +27,7 @@ val virt_var   : ?quoted: bool -> (string * int * int * int) -> string -> t
 val virt_text  : (string * int * int * int) -> string -> t
 val make_var   : ?quoted: bool -> Loc.t -> string -> t
 val make_text  : ?quoted: bool -> Loc.t -> string -> t
+val make_macro : ?quoted: bool -> Loc.t -> string -> string -> t
 
 val is_var : t -> name:string -> bool
 

test/blackbox-tests/dune.inc

@@ -610,6 +610,14 @@
    test-cases/ocamldep-multi-stanzas
    (progn (run %{exe:cram.exe} -test run.t) (diff? run.t run.t.corrected)))))
 
+(alias
+ (name ocamlformat)
+ (deps (package dune) (source_tree test-cases/ocamlformat))
+ (action
+  (chdir
+   test-cases/ocamlformat
+   (progn (run %{exe:cram.exe} -test run.t) (diff? run.t run.t.corrected)))))
+
 (alias
  (name ocamllex-jbuild)
  (deps (package dune) (source_tree test-cases/ocamllex-jbuild))
@@ -960,6 +968,7 @@
   (alias ocaml-config-macro)
   (alias ocaml-syntax)
   (alias ocamldep-multi-stanzas)
+  (alias ocamlformat)
   (alias ocamllex-jbuild)
   (alias odoc)
   (alias odoc-unique-mlds)
@@ -1064,6 +1073,7 @@
   (alias ocaml-config-macro)
   (alias ocaml-syntax)
   (alias ocamldep-multi-stanzas)
+  (alias ocamlformat)
   (alias ocamllex-jbuild)
   (alias output-obj)
   (alias package-dep)

test/blackbox-tests/test-cases/ocamlformat/dune

@@ -0,0 +1,3 @@
+(executable
+ (name ignored)
+)

test/blackbox-tests/test-cases/ocamlformat/dune-project

@@ -0,0 +1 @@
+(lang dune 1.2)

test/blackbox-tests/test-cases/ocamlformat/ignored.ml

@@ -0,0 +1,3 @@
+let () =
+  print_endline
+  "hello"

test/blackbox-tests/test-cases/ocamlformat/lib/dune

@@ -0,0 +1,4 @@
+(library
+ (name lib)
+ (ocamlformat)
+)

test/blackbox-tests/test-cases/ocamlformat/lib/lib.ml.orig

@@ -0,0 +1 @@
+let x  = 1

test/blackbox-tests/test-cases/ocamlformat/lib/lib.mli

@@ -0,0 +1 @@
+val x :  int

test/blackbox-tests/test-cases/ocamlformat/lib2/dune

@@ -0,0 +1,4 @@
+(library
+ (name lib2)
+ (ocamlformat)
+)

test/blackbox-tests/test-cases/ocamlformat/lib2/lib2.ml

@@ -0,0 +1 @@
+let  y=()

test/blackbox-tests/test-cases/ocamlformat/lib2/lib2.mli

@@ -0,0 +1,2 @@
+val y   :
+  unit

test/blackbox-tests/test-cases/ocamlformat/run.t

@@ -0,0 +1,22 @@
+Formatting can be checked using the @format target:
+
+  $ cp lib/lib.ml.orig lib/lib.ml
+  $ dune build @format --diff-command false
+            sh (internal) (exit 1)
+  (cd _build/default && /bin/sh -c 'false lib/lib.ml lib/lib.ml.formatted')
+            sh (internal) (exit 1)
+  (cd _build/default && /bin/sh -c 'false lib/lib.mli lib/lib.mli.formatted')
+            sh (internal) (exit 1)
+  (cd _build/default && /bin/sh -c 'false lib2/lib2.mli lib2/lib2.mli.formatted')
+            sh (internal) (exit 1)
+  (cd _build/default && /bin/sh -c 'false lib2/lib2.ml lib2/lib2.ml.formatted')
+  dir = _build/default/lib2
+  dir = _build/default/lib
+  [1]
+
+And fixable files can be promoted:
+
+  $ dune promote lib/lib.ml
+  Promoting _build/default/lib/lib.ml.formatted to lib/lib.ml.
+  $ cat lib/lib.ml
+  let x = 1