From d1d7672e96e25d51aea1a2098aa81283c135aa31 Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Mon, 27 Aug 2018 18:36:05 +0300
Subject: [PATCH 01/17] wrapped transition mode

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 src/compilation_context.ml                    |  3 +
 src/compilation_context.mli                   |  2 +
 src/dir_contents.ml                           | 22 +++++--
 src/dir_contents.mli                          |  1 +
 src/dune_file.ml                              | 25 ++++++-
 src/dune_file.mli                             | 10 ++-
 src/install_rules.ml                          |  7 +-
 src/js_of_ocaml_rules.ml                      |  8 +--
 src/lib_rules.ml                              | 65 +++++++++++++++----
 src/module.ml                                 | 36 ++++++++++
 src/module.mli                                |  4 ++
 src/ocamldep.ml                               | 17 +++++
 src/ocamldep.mli                              |  5 ++
 src/stanza.ml                                 |  2 +-
 test/blackbox-tests/dune.inc                  | 14 +++-
 .../test-cases/dune-project-edition/run.t     |  6 +-
 .../test-cases/no-name-field/run.t            |  2 +-
 .../test-cases/wrapped-transition/dune        |  7 ++
 .../wrapped-transition/dune-project           |  1 +
 .../test-cases/wrapped-transition/fooexe.ml   |  4 ++
 .../test-cases/wrapped-transition/lib/bar.ml  |  1 +
 .../test-cases/wrapped-transition/lib/dune    |  3 +
 .../test-cases/wrapped-transition/lib/foo.ml  |  1 +
 .../test-cases/wrapped-transition/run.t       |  6 ++
 24 files changed, 216 insertions(+), 36 deletions(-)
 create mode 100644 test/blackbox-tests/test-cases/wrapped-transition/dune
 create mode 100644 test/blackbox-tests/test-cases/wrapped-transition/dune-project
 create mode 100644 test/blackbox-tests/test-cases/wrapped-transition/fooexe.ml
 create mode 100644 test/blackbox-tests/test-cases/wrapped-transition/lib/bar.ml
 create mode 100644 test/blackbox-tests/test-cases/wrapped-transition/lib/dune
 create mode 100644 test/blackbox-tests/test-cases/wrapped-transition/lib/foo.ml
 create mode 100644 test/blackbox-tests/test-cases/wrapped-transition/run.t

diff --git a/src/compilation_context.ml b/src/compilation_context.ml
index 78883c1d..6b39af76 100644
--- a/src/compilation_context.ml
+++ b/src/compilation_context.ml
@@ -105,3 +105,6 @@ let for_alias_module t =
   ; includes     = Includes.empty
   ; alias_module = None
   }
+
+let set_modules t modules =
+  { t with modules }
diff --git a/src/compilation_context.mli b/src/compilation_context.mli
index 529239e8..40cde805 100644
--- a/src/compilation_context.mli
+++ b/src/compilation_context.mli
@@ -48,3 +48,5 @@ val includes             : t -> string list Arg_spec.t Cm_kind.Dict.t
 val preprocessing        : t -> Preprocessing.t
 val no_keep_locs         : t -> bool
 val opaque               : t -> bool
+
+val set_modules : t -> Module.t Module.Name.Map.t -> t
diff --git a/src/dir_contents.ml b/src/dir_contents.ml
index bf565198..3aaf9742 100644
--- a/src/dir_contents.ml
+++ b/src/dir_contents.ml
@@ -168,6 +168,7 @@ module Library_modules : sig
     { modules          : Module.t Module.Name.Map.t
     ; alias_module     : Module.t option
     ; main_module_name : Module.Name.t
+    ; deprecated       : Module.t Module.Name.Map.t
     }
 
   val make : Library.t -> dir:Path.t -> Module.t Module.Name.Map.t -> t
@@ -176,25 +177,32 @@ end = struct
     { modules          : Module.t Module.Name.Map.t
     ; alias_module     : Module.t option
     ; main_module_name : Module.Name.t
+    ; deprecated       : Module.t Module.Name.Map.t
     }
 
   let make (lib : Library.t) ~dir (modules : Module.t Module.Name.Map.t) =
     let main_module_name =
       Module.Name.of_string (Lib_name.Local.to_string lib.name) in
-    let modules =
-      if not lib.wrapped then
-        modules
-      else
+    let (modules, deprecated) =
+      let wrap_modules modules =
         let open Module.Name.Infix in
-        Module.Name.Map.map modules ~f:(fun m ->
+        Module.Name.Map.map modules ~f:(fun (m : Module.t) ->
           if m.name = main_module_name then
             m
           else
             Module.with_wrapper m ~libname:lib.name)
+      in
+      match lib.wrapped with
+      | Simple false -> (modules, Module.Name.Map.empty)
+      | Simple true -> (wrap_modules modules, Module.Name.Map.empty)
+      | Yes_with_transition _ ->
+        ( wrap_modules modules
+        , Module.Name.Map.map ~f:Module.deprecate modules
+        )
     in
     let alias_module =
       let lib_name = Lib_name.Local.to_string lib.name in
-      if not lib.wrapped ||
+      if not (Library.Wrapped.to_bool lib.wrapped) ||
          (Module.Name.Map.cardinal modules = 1 &&
           Module.Name.Map.mem modules main_module_name) then
         None
@@ -215,7 +223,7 @@ end = struct
                       (Path.relative dir (lib_name ^ ".ml-gen")))
              ~obj_name:lib_name)
     in
-    { modules; alias_module; main_module_name }
+    { modules; alias_module; main_module_name; deprecated }
 end
 
 module Executables_modules = struct
diff --git a/src/dir_contents.mli b/src/dir_contents.mli
index 09833d17..ca96ce43 100644
--- a/src/dir_contents.mli
+++ b/src/dir_contents.mli
@@ -21,6 +21,7 @@ module Library_modules : sig
     { modules          : Module.t Module.Name.Map.t
     ; alias_module     : Module.t option
     ; main_module_name : Module.Name.t
+    ; deprecated       : Module.t Module.Name.Map.t
     }
 end
 
diff --git a/src/dune_file.ml b/src/dune_file.ml
index 1bb6a9c4..b31e7bf6 100644
--- a/src/dune_file.ml
+++ b/src/dune_file.ml
@@ -859,6 +859,25 @@ module Library = struct
       syntax
   end
 
+  module Wrapped = struct
+    type t =
+      | Simple of bool
+      | Yes_with_transition of string
+
+    let dparse =
+      if_list
+        ~then_:(
+          Syntax.since Stanza.syntax (1, 2) >>= fun () ->
+          sum ["transition_until", string >>| fun x -> Yes_with_transition x])
+        ~else_:(bool >>| fun w -> Simple w)
+
+    let field = field "wrapped" ~default:(Simple true) dparse
+
+    let to_bool = function
+      | Simple b -> b
+      | Yes_with_transition _ -> true
+  end
+
   type t =
     { name                     : Lib_name.Local.t
     ; public                   : Public_lib.t option
@@ -875,7 +894,7 @@ module Library = struct
     ; c_library_flags          : Ordered_set_lang.Unexpanded.t
     ; self_build_stubs_archive : string option
     ; virtual_deps             : (Loc.t * Lib_name.t) list
-    ; wrapped                  : bool
+    ; wrapped                  : Wrapped.t
     ; optional                 : bool
     ; buildable                : Buildable.t
     ; dynlink                  : Dynlink_supported.t
@@ -908,7 +927,7 @@ module Library = struct
          field "virtual_deps" (list (located Lib_name.dparse)) ~default:[]
        and modes = field "modes" Mode_conf.Set.dparse ~default:Mode_conf.Set.default
        and kind = field "kind" Kind.dparse ~default:Kind.Normal
-       and wrapped = field "wrapped" bool ~default:true
+       and wrapped = Wrapped.field
        and optional = field_b "optional"
        and self_build_stubs_archive =
          field "self_build_stubs_archive" (option string) ~default:None
@@ -932,7 +951,7 @@ module Library = struct
          let open Syntax.Version.Infix in
          match name, public with
          | Some n, _ ->
-           Lib_name.Local.validate n ~wrapped
+           Lib_name.Local.validate n ~wrapped:(Wrapped.to_bool wrapped)
          | None, Some { name = (loc, name) ; _ }  ->
            if dune_version >= (1, 1) then
              match Lib_name.to_local name with
diff --git a/src/dune_file.mli b/src/dune_file.mli
index 0823c813..c462c5d0 100644
--- a/src/dune_file.mli
+++ b/src/dune_file.mli
@@ -216,6 +216,14 @@ module Library : sig
       | Ppx_rewriter
   end
 
+  module Wrapped : sig
+    type t =
+      | Simple of bool
+      | Yes_with_transition of string
+
+    val to_bool : t -> bool
+  end
+
   type t =
     { name                     : Lib_name.Local.t
     ; public                   : Public_lib.t option
@@ -232,7 +240,7 @@ module Library : sig
     ; c_library_flags          : Ordered_set_lang.Unexpanded.t
     ; self_build_stubs_archive : string option
     ; virtual_deps             : (Loc.t * Lib_name.t) list
-    ; wrapped                  : bool
+    ; wrapped                  : Wrapped.t
     ; optional                 : bool
     ; buildable                : Buildable.t
     ; dynlink                  : Dynlink_supported.t
diff --git a/src/install_rules.ml b/src/install_rules.ml
index c832d925..31620633 100644
--- a/src/install_rules.ml
+++ b/src/install_rules.ml
@@ -138,7 +138,8 @@ module Gen(P : Params) = struct
     let if_ cond l = if cond then l else [] in
     let files =
       let modules =
-        let { Dir_contents.Library_modules.modules; alias_module; _ } =
+        let { Dir_contents.Library_modules.modules; alias_module; deprecated
+            ; main_module_name = _ } =
           Dir_contents.modules_of_library dir_contents
             ~name:(Library.best_name lib)
         in
@@ -147,7 +148,9 @@ module Gen(P : Params) = struct
           | None -> modules
           | Some m -> Module.Name.Map.add modules m.name m
         in
-        Module.Name.Map.values modules
+        List.rev_append
+          (Module.Name.Map.values modules)
+          (Module.Name.Map.values deprecated)
       in
       let virtual_library = Library.is_virtual lib in
       List.concat
diff --git a/src/js_of_ocaml_rules.ml b/src/js_of_ocaml_rules.ml
index 3d13a464..76bf7943 100644
--- a/src/js_of_ocaml_rules.ml
+++ b/src/js_of_ocaml_rules.ml
@@ -113,15 +113,15 @@ let link_rule cc ~runtime ~target =
     ; Arg_spec.Dyn get_all
     ]
 
-let build_cm cc ~(js_of_ocaml:Dune_file.Js_of_ocaml.t) ~src ~target =
-  let sctx = Compilation_context.super_context cc in
-  let dir = Compilation_context.dir cc in
+let build_cm cctx ~(js_of_ocaml:Dune_file.Js_of_ocaml.t) ~src ~target =
+  let sctx = Compilation_context.super_context cctx in
+  let dir = Compilation_context.dir cctx in
   if separate_compilation_enabled sctx
   then
     let itarget = Path.extend_basename src ~suffix:".js" in
     let spec = Arg_spec.Dep src in
     let flags =
-      let scope = Compilation_context.scope cc in
+      let scope = Compilation_context.scope cctx in
       SC.expand_and_eval_set sctx ~scope ~dir js_of_ocaml.flags
         ~standard:(Build.return (standard sctx))
     in
diff --git a/src/lib_rules.ml b/src/lib_rules.ml
index 2db4c20a..255d0174 100644
--- a/src/lib_rules.ml
+++ b/src/lib_rules.ml
@@ -120,6 +120,37 @@ module Gen (P : Install_rules.Params) = struct
       ~sandbox:alias_module_build_sandbox
       ~dep_graphs:(Ocamldep.Dep_graphs.dummy m)
 
+  let build_deprecated_modules (lib : Library.t)
+        cctx
+        ~modules
+        ~js_of_ocaml
+        ~dynlink
+        ~(deprecated : Module.t Module.Name.Map.t) =
+    let lib_name = String.capitalize (Lib_name.Local.to_string lib.name) in
+    let transition_until =
+      match lib.wrapped with
+      | Simple _ -> "" (* will never be accessed anyway *)
+      | Yes_with_transition r -> r
+    in
+    Module.Name.Map.iteri deprecated ~f:(fun name m ->
+      let contents =
+        let name = Module.Name.to_string name in
+        let hidden_name = sprintf "%s__%s" lib_name name in
+        let real_name = sprintf "%s.%s" lib_name name in
+        sprintf "include %s [@@deprecated \"%s is not guaranteed past %s. \
+                 Use %s instead.\"]"
+          hidden_name name transition_until real_name
+      in
+      let source_path = Option.value_exn (Module.file m Impl) in
+      Build.return contents
+      >>> Build.write_file_dyn source_path
+      |> SC.add_rule sctx
+    );
+    let dep_graphs =
+      Ocamldep.Dep_graphs.deprecated ~modules ~deprecated in
+    let cctx = Compilation_context.set_modules cctx deprecated in
+    Module_compilation.build_modules cctx ~js_of_ocaml ~dynlink ~dep_graphs
+
   let build_c_file (lib : Library.t) ~scope ~dir ~includes (src, dst) =
     SC.add_rule sctx
       (SC.expand_and_eval_set sctx ~scope ~dir lib.c_flags
@@ -293,7 +324,7 @@ module Gen (P : Install_rules.Params) = struct
     in
     let flags = SC.ocaml_flags sctx ~scope ~dir lib.buildable in
     let { Dir_contents.Library_modules.
-          modules; main_module_name; alias_module } =
+          modules; main_module_name; alias_module ; deprecated } =
       Dir_contents.modules_of_library dir_contents ~name:(Library.best_name lib)
     in
     let source_modules = modules in
@@ -318,7 +349,7 @@ module Gen (P : Install_rules.Params) = struct
     in
 
     let lib_interface_module =
-      if lib.wrapped then
+      if Library.Wrapped.to_bool lib.wrapped then
         Module.Name.Map.find modules main_module_name
       else
         None
@@ -340,12 +371,16 @@ module Gen (P : Install_rules.Params) = struct
         ~opaque
     in
 
-    let dep_graphs = Ocamldep.rules cctx in
-
     let dynlink =
       Dynlink_supported.get lib.dynlink ctx.supports_shared_libraries
     in
     let js_of_ocaml = lib.buildable.js_of_ocaml in
+
+    build_deprecated_modules lib cctx ~dynlink ~js_of_ocaml
+      ~deprecated ~modules;
+
+    let dep_graphs = Ocamldep.rules cctx in
+
     Module_compilation.build_modules cctx ~js_of_ocaml ~dynlink ~dep_graphs;
 
     Option.iter alias_module
@@ -355,15 +390,17 @@ module Gen (P : Install_rules.Params) = struct
     if Library.has_stubs lib then
       build_stubs lib ~dir ~scope ~requires ~dir_contents;
 
+    let add_cms ~cm_kind ~init = Module.Name.Map.fold ~init ~f:(fun m acc ->
+      match Module.cm_file m ~obj_dir cm_kind with
+      | None -> acc
+      | Some fn -> Path.Set.add acc fn)
+    in
     List.iter Cm_kind.all ~f:(fun cm_kind ->
-      let files =
-        Module.Name.Map.fold modules ~init:Path.Set.empty ~f:(fun m acc ->
-          match Module.cm_file m ~obj_dir cm_kind with
-          | None -> acc
-          | Some fn -> Path.Set.add acc fn)
-      in
+      let files = add_cms ~cm_kind ~init:Path.Set.empty modules in
+      let files = add_cms ~cm_kind ~init:files deprecated in
       SC.Libs.setup_file_deps_alias sctx ~dir lib ~ext:(Cm_kind.ext cm_kind)
         files);
+
     SC.Libs.setup_file_deps_group_alias sctx ~dir lib ~exts:[".cmi"; ".cmx"];
     SC.Libs.setup_file_deps_alias sctx ~dir lib ~ext:".h"
       (List.map lib.install_c_headers ~f:(fun header ->
@@ -377,12 +414,16 @@ module Gen (P : Install_rules.Params) = struct
          else
            acc)
      in
+     let deprecated_modules = Module.Name.Map.values deprecated in
+     (* deprecated modules have implementations so we can just append them *)
      let top_sorted_modules =
        Ocamldep.Dep_graph.top_closed_implementations dep_graphs.impl modules
+       >>^ fun modules -> modules @ deprecated_modules
      in
-     List.iter Mode.all ~f:(fun mode ->
+     (let modules = modules @ deprecated_modules in
+        List.iter Mode.all ~f:(fun mode ->
        build_lib lib ~scope ~flags ~dir ~obj_dir ~mode ~top_sorted_modules
-         ~modules));
+         ~modules)));
     (* Build *.cma.js *)
     SC.add_rules sctx (
       let src = Library.archive lib ~dir ~ext:(Mode.compiled_lib_ext Mode.Byte) in
diff --git a/src/module.ml b/src/module.ml
index b06c6e7f..c7d26694 100644
--- a/src/module.ml
+++ b/src/module.ml
@@ -32,6 +32,12 @@ end
 
 module Syntax = struct
   type t = OCaml | Reason
+
+  let to_sexp =
+    let open Sexp.To_sexp in
+    function
+    | OCaml -> string "OCaml"
+    | Reason -> string "Reason"
 end
 
 module File = struct
@@ -41,6 +47,13 @@ module File = struct
     }
 
   let make syntax path = { syntax; path }
+
+  let to_sexp { path; syntax } =
+    let open Sexp.To_sexp in
+    record
+      [ "path", Path.to_sexp path
+      ; "syntax", Syntax.to_sexp syntax
+      ]
 end
 
 type t =
@@ -140,3 +153,26 @@ let dir t =
   Path.parent_exn file.path
 
 let set_pp t pp = { t with pp }
+
+let to_sexp { name; impl; intf; obj_name ; pp } =
+  let open Sexp.To_sexp in
+  record
+    [ "name", Name.to_sexp name
+    ; "obj_name", string obj_name
+    ; "impl", (option File.to_sexp) impl
+    ; "intf", (option File.to_sexp) intf
+    ; "pp", (option string) (Option.map ~f:(fun _ -> "has pp") pp)
+    ]
+
+let deprecate t =
+  { t with
+    intf = None
+  ; impl =
+      Some (
+        let impl = Option.value_exn t.impl in
+        let (base, _) = Path.split_extension impl.path in
+        { syntax = OCaml
+        ; path = Path.extend_basename base ~suffix:".ml-gen"
+        }
+      )
+  }
diff --git a/src/module.mli b/src/module.mli
index 4ac943b9..4e3201da 100644
--- a/src/module.mli
+++ b/src/module.mli
@@ -92,3 +92,7 @@ val with_wrapper : t -> libname:Lib_name.Local.t -> t
 val map_files : t -> f:(Ml_kind.t -> File.t -> File.t) -> t
 
 val set_pp : t -> (unit, string list) Build.t option -> t
+
+val to_sexp : t Sexp.To_sexp.t
+
+val deprecate : t -> t
diff --git a/src/ocamldep.ml b/src/ocamldep.ml
index 9d60073c..1a5d134d 100644
--- a/src/ocamldep.ml
+++ b/src/ocamldep.ml
@@ -51,6 +51,20 @@ module Dep_graph = struct
     { dir = Path.root
     ; per_module = Module.Name.Map.singleton m.name (Build.return [])
     }
+
+  let deprecated ~modules ~deprecated =
+    { dir = Path.root
+    ; per_module = Module.Name.Map.merge deprecated modules ~f:(fun _ d m ->
+        match d, m with
+        | None, None -> assert false
+        | Some deprecated, None ->
+          Exn.code_error "deprecated module needs counterpart"
+            [ "deprecated", Module.to_sexp deprecated
+            ]
+        | None, Some _ -> None
+        | Some _, Some m -> Some (Build.return [m])
+      )
+    }
 end
 
 module Dep_graphs = struct
@@ -58,6 +72,9 @@ module Dep_graphs = struct
 
   let dummy m =
     Ml_kind.Dict.make_both (Dep_graph.dummy m)
+
+  let deprecated ~modules ~deprecated =
+    Ml_kind.Dict.make_both (Dep_graph.deprecated ~modules ~deprecated)
 end
 
 let parse_module_names ~(unit : Module.t) ~modules words =
diff --git a/src/ocamldep.mli b/src/ocamldep.mli
index 653f4904..83028590 100644
--- a/src/ocamldep.mli
+++ b/src/ocamldep.mli
@@ -18,6 +18,11 @@ module Dep_graphs : sig
   type t = Dep_graph.t Ml_kind.Dict.t
 
   val dummy : Module.t -> t
+
+  val deprecated
+    :  modules:Module.t Module.Name.Map.t
+    -> deprecated:Module.t Module.Name.Map.t
+    -> t
 end
 
 (** Generate ocamldep rules for all the modules in the context. *)
diff --git a/src/stanza.ml b/src/stanza.ml
index e4b92120..0d60784b 100644
--- a/src/stanza.ml
+++ b/src/stanza.ml
@@ -9,7 +9,7 @@ end
 let syntax =
   Syntax.create ~name:"dune" ~desc:"the dune language"
     [ (0, 0) (* Jbuild syntax *)
-    ; (1, 1)
+    ; (1, 2)
     ]
 
 module File_kind = struct
diff --git a/test/blackbox-tests/dune.inc b/test/blackbox-tests/dune.inc
index be56c3da..1f5680f3 100644
--- a/test/blackbox-tests/dune.inc
+++ b/test/blackbox-tests/dune.inc
@@ -836,6 +836,14 @@
    test-cases/workspaces
    (progn (run %{exe:cram.exe} -test run.t) (diff? run.t run.t.corrected)))))
 
+(alias
+ (name wrapped-transition)
+ (deps (package dune) (source_tree test-cases/wrapped-transition))
+ (action
+  (chdir
+   test-cases/wrapped-transition
+   (progn (run %{exe:cram.exe} -test run.t) (diff? run.t run.t.corrected)))))
+
 (alias
  (name runtest)
  (deps
@@ -938,7 +946,8 @@
   (alias utop-default)
   (alias variants)
   (alias windows-diff)
-  (alias workspaces)))
+  (alias workspaces)
+  (alias wrapped-transition)))
 
 (alias
  (name runtest-no-deps)
@@ -1029,7 +1038,8 @@
   (alias utop-default)
   (alias variants)
   (alias windows-diff)
-  (alias workspaces)))
+  (alias workspaces)
+  (alias wrapped-transition)))
 
 (alias (name runtest-disabled) (deps (alias envs-and-contexts)))
 
diff --git a/test/blackbox-tests/test-cases/dune-project-edition/run.t b/test/blackbox-tests/test-cases/dune-project-edition/run.t
index 311d7d88..2fe9158f 100644
--- a/test/blackbox-tests/test-cases/dune-project-edition/run.t
+++ b/test/blackbox-tests/test-cases/dune-project-edition/run.t
@@ -3,9 +3,9 @@
   $ mkdir src
   $ echo '(alias (name runtest) (action (progn)))' >  src/dune
   $ dune build
-  Info: creating file dune-project with this contents: (lang dune 1.1)
+  Info: creating file dune-project with this contents: (lang dune 1.2)
   $ cat dune-project
-  (lang dune 1.1)
+  (lang dune 1.2)
 
 Test that using menhir automatically update the dune-project file
 
@@ -13,5 +13,5 @@ Test that using menhir automatically update the dune-project file
   $ dune build
   Info: appending this line to dune-project: (using menhir 1.0)
   $ cat dune-project
-  (lang dune 1.1)
+  (lang dune 1.2)
   (using menhir 1.0)
diff --git a/test/blackbox-tests/test-cases/no-name-field/run.t b/test/blackbox-tests/test-cases/no-name-field/run.t
index bbe69b55..449e053d 100644
--- a/test/blackbox-tests/test-cases/no-name-field/run.t
+++ b/test/blackbox-tests/test-cases/no-name-field/run.t
@@ -37,7 +37,7 @@ there's only a public name which is invalid, but sine the library is unwrapped,
 it's just a warning
 
   $ dune build --root public-name-invalid-wrapped-false
-  Info: creating file dune-project with this contents: (lang dune 1.1)
+  Info: creating file dune-project with this contents: (lang dune 1.2)
   File "dune", line 3, characters 14-21:
    (public_name foo.bar))
                 ^^^^^^^
diff --git a/test/blackbox-tests/test-cases/wrapped-transition/dune b/test/blackbox-tests/test-cases/wrapped-transition/dune
new file mode 100644
index 00000000..ce2f67cb
--- /dev/null
+++ b/test/blackbox-tests/test-cases/wrapped-transition/dune
@@ -0,0 +1,7 @@
+(executable
+ (name fooexe)
+ (libraries mylib))
+
+(alias
+ (name default)
+ (action (run ./fooexe.exe)))
\ No newline at end of file
diff --git a/test/blackbox-tests/test-cases/wrapped-transition/dune-project b/test/blackbox-tests/test-cases/wrapped-transition/dune-project
new file mode 100644
index 00000000..47f0de83
--- /dev/null
+++ b/test/blackbox-tests/test-cases/wrapped-transition/dune-project
@@ -0,0 +1 @@
+(lang dune 1.2)
\ No newline at end of file
diff --git a/test/blackbox-tests/test-cases/wrapped-transition/fooexe.ml b/test/blackbox-tests/test-cases/wrapped-transition/fooexe.ml
new file mode 100644
index 00000000..05f52bc8
--- /dev/null
+++ b/test/blackbox-tests/test-cases/wrapped-transition/fooexe.ml
@@ -0,0 +1,4 @@
+Mylib.Bar.run ();;
+Mylib.Foo.run ();;
+Bar.run ();;
+Foo.run ();;
diff --git a/test/blackbox-tests/test-cases/wrapped-transition/lib/bar.ml b/test/blackbox-tests/test-cases/wrapped-transition/lib/bar.ml
new file mode 100644
index 00000000..75e45f5d
--- /dev/null
+++ b/test/blackbox-tests/test-cases/wrapped-transition/lib/bar.ml
@@ -0,0 +1 @@
+let run () = print_endline "bar"
diff --git a/test/blackbox-tests/test-cases/wrapped-transition/lib/dune b/test/blackbox-tests/test-cases/wrapped-transition/lib/dune
new file mode 100644
index 00000000..019f3b0c
--- /dev/null
+++ b/test/blackbox-tests/test-cases/wrapped-transition/lib/dune
@@ -0,0 +1,3 @@
+(library
+ (name mylib)
+ (wrapped (transition_until "2020-20-20")))
\ No newline at end of file
diff --git a/test/blackbox-tests/test-cases/wrapped-transition/lib/foo.ml b/test/blackbox-tests/test-cases/wrapped-transition/lib/foo.ml
new file mode 100644
index 00000000..66de3158
--- /dev/null
+++ b/test/blackbox-tests/test-cases/wrapped-transition/lib/foo.ml
@@ -0,0 +1 @@
+let run () = print_endline "foo"
diff --git a/test/blackbox-tests/test-cases/wrapped-transition/run.t b/test/blackbox-tests/test-cases/wrapped-transition/run.t
new file mode 100644
index 00000000..2e9a5d3b
--- /dev/null
+++ b/test/blackbox-tests/test-cases/wrapped-transition/run.t
@@ -0,0 +1,6 @@
+  $ dune build
+        fooexe alias default
+  bar
+  foo
+  bar
+  foo

From 492286ba120b06860d75350caff8f082a0dbe9f8 Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Wed, 29 Aug 2018 13:12:18 +0300
Subject: [PATCH 02/17] Don't hardcode the transition message to be date based

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 src/dune_file.ml                                           | 2 +-
 src/lib_rules.ml                                           | 7 +++----
 test/blackbox-tests/test-cases/wrapped-transition/lib/dune | 2 +-
 3 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/dune_file.ml b/src/dune_file.ml
index b31e7bf6..7421d4b6 100644
--- a/src/dune_file.ml
+++ b/src/dune_file.ml
@@ -868,7 +868,7 @@ module Library = struct
       if_list
         ~then_:(
           Syntax.since Stanza.syntax (1, 2) >>= fun () ->
-          sum ["transition_until", string >>| fun x -> Yes_with_transition x])
+          sum ["transition", string >>| fun x -> Yes_with_transition x])
         ~else_:(bool >>| fun w -> Simple w)
 
     let field = field "wrapped" ~default:(Simple true) dparse
diff --git a/src/lib_rules.ml b/src/lib_rules.ml
index 255d0174..7deb093c 100644
--- a/src/lib_rules.ml
+++ b/src/lib_rules.ml
@@ -127,7 +127,7 @@ module Gen (P : Install_rules.Params) = struct
         ~dynlink
         ~(deprecated : Module.t Module.Name.Map.t) =
     let lib_name = String.capitalize (Lib_name.Local.to_string lib.name) in
-    let transition_until =
+    let transition_message =
       match lib.wrapped with
       | Simple _ -> "" (* will never be accessed anyway *)
       | Yes_with_transition r -> r
@@ -137,9 +137,8 @@ module Gen (P : Install_rules.Params) = struct
         let name = Module.Name.to_string name in
         let hidden_name = sprintf "%s__%s" lib_name name in
         let real_name = sprintf "%s.%s" lib_name name in
-        sprintf "include %s [@@deprecated \"%s is not guaranteed past %s. \
-                 Use %s instead.\"]"
-          hidden_name name transition_until real_name
+        sprintf "include %s [@@deprecated \"%s. Use %s instead.\"]"
+          hidden_name transition_message real_name
       in
       let source_path = Option.value_exn (Module.file m Impl) in
       Build.return contents
diff --git a/test/blackbox-tests/test-cases/wrapped-transition/lib/dune b/test/blackbox-tests/test-cases/wrapped-transition/lib/dune
index 019f3b0c..29516cc2 100644
--- a/test/blackbox-tests/test-cases/wrapped-transition/lib/dune
+++ b/test/blackbox-tests/test-cases/wrapped-transition/lib/dune
@@ -1,3 +1,3 @@
 (library
  (name mylib)
- (wrapped (transition_until "2020-20-20")))
\ No newline at end of file
+ (wrapped (transition "Will be removed past 2020-20-20")))
\ No newline at end of file

From f9ad608e8cf9b033810410c7a532d090c367ef56 Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Wed, 29 Aug 2018 13:14:51 +0300
Subject: [PATCH 03/17] Fix deprecation attribute for transition modules

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 src/lib_rules.ml                                    |  4 ++--
 .../test-cases/wrapped-transition/run.t             | 13 +++++++------
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/src/lib_rules.ml b/src/lib_rules.ml
index 7deb093c..6f5abe3f 100644
--- a/src/lib_rules.ml
+++ b/src/lib_rules.ml
@@ -137,8 +137,8 @@ module Gen (P : Install_rules.Params) = struct
         let name = Module.Name.to_string name in
         let hidden_name = sprintf "%s__%s" lib_name name in
         let real_name = sprintf "%s.%s" lib_name name in
-        sprintf "include %s [@@deprecated \"%s. Use %s instead.\"]"
-          hidden_name transition_message real_name
+        sprintf {|[@@@deprecated "%s. Use %s instead."] include %s|}
+          transition_message real_name hidden_name
       in
       let source_path = Option.value_exn (Module.file m Impl) in
       Build.return contents
diff --git a/test/blackbox-tests/test-cases/wrapped-transition/run.t b/test/blackbox-tests/test-cases/wrapped-transition/run.t
index 2e9a5d3b..76b1fea0 100644
--- a/test/blackbox-tests/test-cases/wrapped-transition/run.t
+++ b/test/blackbox-tests/test-cases/wrapped-transition/run.t
@@ -1,6 +1,7 @@
-  $ dune build
-        fooexe alias default
-  bar
-  foo
-  bar
-  foo
+  $ dune build 2>&1 | grep -v ocamlc
+  File "fooexe.ml", line 3, characters 0-7:
+  Error (warning 3): deprecated: module Bar
+  Will be removed past 2020-20-20. Use Mylib.Bar instead.
+  File "fooexe.ml", line 4, characters 0-7:
+  Error (warning 3): deprecated: module Foo
+  Will be removed past 2020-20-20. Use Mylib.Foo instead.

From d0b937c25e18bd85b22ca829de7cf9187fd7abbe Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Wed, 29 Aug 2018 15:00:21 +0300
Subject: [PATCH 04/17] Use proper sum type wrapped.t

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 src/dune_file.ml | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/dune_file.ml b/src/dune_file.ml
index 7421d4b6..924d42a6 100644
--- a/src/dune_file.ml
+++ b/src/dune_file.ml
@@ -865,11 +865,11 @@ module Library = struct
       | Yes_with_transition of string
 
     let dparse =
-      if_list
-        ~then_:(
-          Syntax.since Stanza.syntax (1, 2) >>= fun () ->
-          sum ["transition", string >>| fun x -> Yes_with_transition x])
-        ~else_:(bool >>| fun w -> Simple w)
+      sum
+        [ "true", return (Simple true)
+        ; "false", return (Simple false)
+        ; "transition", string >>| fun x -> Yes_with_transition x
+        ]
 
     let field = field "wrapped" ~default:(Simple true) dparse
 

From 8acca614dae94fed321b6cc43d030cd5cb49ec6d Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Wed, 29 Aug 2018 20:20:07 +0300
Subject: [PATCH 05/17] Use dedicated compilation context for deprecated
 modules

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 src/compilation_context.ml  | 9 +++++++--
 src/compilation_context.mli | 2 +-
 src/lib_rules.ml            | 2 +-
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/compilation_context.ml b/src/compilation_context.ml
index 6b39af76..9f572dc4 100644
--- a/src/compilation_context.ml
+++ b/src/compilation_context.ml
@@ -106,5 +106,10 @@ let for_alias_module t =
   ; alias_module = None
   }
 
-let set_modules t modules =
-  { t with modules }
+let for_deprecated t modules =
+  { t with
+    flags = Ocaml_flags.default ~profile:(SC.profile t.super_context)
+  ; includes = Includes.empty
+  ; alias_module = None
+  ; modules
+  }
diff --git a/src/compilation_context.mli b/src/compilation_context.mli
index 40cde805..a4bf2dc4 100644
--- a/src/compilation_context.mli
+++ b/src/compilation_context.mli
@@ -49,4 +49,4 @@ val preprocessing        : t -> Preprocessing.t
 val no_keep_locs         : t -> bool
 val opaque               : t -> bool
 
-val set_modules : t -> Module.t Module.Name.Map.t -> t
+val for_deprecated : t -> Module.t Module.Name.Map.t -> t
diff --git a/src/lib_rules.ml b/src/lib_rules.ml
index 6f5abe3f..8f71bd7c 100644
--- a/src/lib_rules.ml
+++ b/src/lib_rules.ml
@@ -147,7 +147,7 @@ module Gen (P : Install_rules.Params) = struct
     );
     let dep_graphs =
       Ocamldep.Dep_graphs.deprecated ~modules ~deprecated in
-    let cctx = Compilation_context.set_modules cctx deprecated in
+    let cctx = Compilation_context.for_deprecated cctx deprecated in
     Module_compilation.build_modules cctx ~js_of_ocaml ~dynlink ~dep_graphs
 
   let build_c_file (lib : Library.t) ~scope ~dir ~includes (src, dst) =

From f47834d80b3fe6300bbd61ea0e0278b9f10136ec Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Wed, 29 Aug 2018 20:22:59 +0300
Subject: [PATCH 06/17] Add modules_without_implementation example to wrapped
 transition mode

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 src/module.ml                                       | 13 +++++++++----
 .../test-cases/wrapped-transition/fooexe.ml         |  3 +++
 .../test-cases/wrapped-transition/lib/dune          |  1 +
 .../test-cases/wrapped-transition/lib/intf_only.mli |  1 +
 4 files changed, 14 insertions(+), 4 deletions(-)
 create mode 100644 test/blackbox-tests/test-cases/wrapped-transition/lib/intf_only.mli

diff --git a/src/module.ml b/src/module.ml
index c7d26694..2ef21c34 100644
--- a/src/module.ml
+++ b/src/module.ml
@@ -166,11 +166,16 @@ let to_sexp { name; impl; intf; obj_name ; pp } =
 
 let deprecate t =
   { t with
-    intf = None
-  ; impl =
+    impl =
       Some (
-        let impl = Option.value_exn t.impl in
-        let (base, _) = Path.split_extension impl.path in
+        let path =
+          match t.intf, t.impl with
+          | Some _, Some impl
+          | None, Some impl -> impl.path
+          | Some intf, _ -> intf.path
+          | None, None -> assert false
+        in
+        let (base, _) = Path.split_extension path in
         { syntax = OCaml
         ; path = Path.extend_basename base ~suffix:".ml-gen"
         }
diff --git a/test/blackbox-tests/test-cases/wrapped-transition/fooexe.ml b/test/blackbox-tests/test-cases/wrapped-transition/fooexe.ml
index 05f52bc8..7ea5bdc1 100644
--- a/test/blackbox-tests/test-cases/wrapped-transition/fooexe.ml
+++ b/test/blackbox-tests/test-cases/wrapped-transition/fooexe.ml
@@ -2,3 +2,6 @@ Mylib.Bar.run ();;
 Mylib.Foo.run ();;
 Bar.run ();;
 Foo.run ();;
+
+module Y : Mylib.Intf_only.S = struct end
+module X : Intf_only.S = struct end
diff --git a/test/blackbox-tests/test-cases/wrapped-transition/lib/dune b/test/blackbox-tests/test-cases/wrapped-transition/lib/dune
index 29516cc2..8cd2dab1 100644
--- a/test/blackbox-tests/test-cases/wrapped-transition/lib/dune
+++ b/test/blackbox-tests/test-cases/wrapped-transition/lib/dune
@@ -1,3 +1,4 @@
 (library
  (name mylib)
+ (modules_without_implementation intf_only)
  (wrapped (transition "Will be removed past 2020-20-20")))
\ No newline at end of file
diff --git a/test/blackbox-tests/test-cases/wrapped-transition/lib/intf_only.mli b/test/blackbox-tests/test-cases/wrapped-transition/lib/intf_only.mli
new file mode 100644
index 00000000..d63d6c08
--- /dev/null
+++ b/test/blackbox-tests/test-cases/wrapped-transition/lib/intf_only.mli
@@ -0,0 +1 @@
+module type S = sig end

From c8970ab9777e5f4c19676d14f55a30f4024f30c0 Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Wed, 29 Aug 2018 21:20:31 +0300
Subject: [PATCH 07/17] Change terminology to wrapped_compat

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 src/compilation_context.ml  |  2 +-
 src/compilation_context.mli |  2 +-
 src/dir_contents.ml         | 12 ++++++++----
 src/dir_contents.mli        |  2 +-
 src/install_rules.ml        |  7 +++++--
 src/lib_rules.ml            | 20 ++++++++++----------
 src/ocamldep.ml             | 12 ++++++------
 src/ocamldep.mli            |  4 ++--
 8 files changed, 34 insertions(+), 27 deletions(-)

diff --git a/src/compilation_context.ml b/src/compilation_context.ml
index 9f572dc4..d71550a8 100644
--- a/src/compilation_context.ml
+++ b/src/compilation_context.ml
@@ -106,7 +106,7 @@ let for_alias_module t =
   ; alias_module = None
   }
 
-let for_deprecated t modules =
+let for_wrapped_compat t modules =
   { t with
     flags = Ocaml_flags.default ~profile:(SC.profile t.super_context)
   ; includes = Includes.empty
diff --git a/src/compilation_context.mli b/src/compilation_context.mli
index a4bf2dc4..4460f90e 100644
--- a/src/compilation_context.mli
+++ b/src/compilation_context.mli
@@ -49,4 +49,4 @@ val preprocessing        : t -> Preprocessing.t
 val no_keep_locs         : t -> bool
 val opaque               : t -> bool
 
-val for_deprecated : t -> Module.t Module.Name.Map.t -> t
+val for_wrapped_compat : t -> Module.t Module.Name.Map.t -> t
diff --git a/src/dir_contents.ml b/src/dir_contents.ml
index 3aaf9742..5401b8a3 100644
--- a/src/dir_contents.ml
+++ b/src/dir_contents.ml
@@ -168,7 +168,7 @@ module Library_modules : sig
     { modules          : Module.t Module.Name.Map.t
     ; alias_module     : Module.t option
     ; main_module_name : Module.Name.t
-    ; deprecated       : Module.t Module.Name.Map.t
+    ; wrapped_compat   : Module.t Module.Name.Map.t
     }
 
   val make : Library.t -> dir:Path.t -> Module.t Module.Name.Map.t -> t
@@ -177,13 +177,13 @@ end = struct
     { modules          : Module.t Module.Name.Map.t
     ; alias_module     : Module.t option
     ; main_module_name : Module.Name.t
-    ; deprecated       : Module.t Module.Name.Map.t
+    ; wrapped_compat   : Module.t Module.Name.Map.t
     }
 
   let make (lib : Library.t) ~dir (modules : Module.t Module.Name.Map.t) =
     let main_module_name =
       Module.Name.of_string (Lib_name.Local.to_string lib.name) in
-    let (modules, deprecated) =
+    let (modules, wrapped_compat) =
       let wrap_modules modules =
         let open Module.Name.Infix in
         Module.Name.Map.map modules ~f:(fun (m : Module.t) ->
@@ -223,7 +223,11 @@ end = struct
                       (Path.relative dir (lib_name ^ ".ml-gen")))
              ~obj_name:lib_name)
     in
-    { modules; alias_module; main_module_name; deprecated }
+    { modules
+    ; alias_module
+    ; main_module_name
+    ; wrapped_compat
+    }
 end
 
 module Executables_modules = struct
diff --git a/src/dir_contents.mli b/src/dir_contents.mli
index ca96ce43..3430d239 100644
--- a/src/dir_contents.mli
+++ b/src/dir_contents.mli
@@ -21,7 +21,7 @@ module Library_modules : sig
     { modules          : Module.t Module.Name.Map.t
     ; alias_module     : Module.t option
     ; main_module_name : Module.Name.t
-    ; deprecated       : Module.t Module.Name.Map.t
+    ; wrapped_compat   : Module.t Module.Name.Map.t
     }
 end
 
diff --git a/src/install_rules.ml b/src/install_rules.ml
index 31620633..d7cdf09e 100644
--- a/src/install_rules.ml
+++ b/src/install_rules.ml
@@ -138,7 +138,10 @@ module Gen(P : Params) = struct
     let if_ cond l = if cond then l else [] in
     let files =
       let modules =
-        let { Dir_contents.Library_modules.modules; alias_module; deprecated
+        let { Dir_contents.Library_modules.
+              modules
+            ; alias_module
+            ; wrapped_compat
             ; main_module_name = _ } =
           Dir_contents.modules_of_library dir_contents
             ~name:(Library.best_name lib)
@@ -150,7 +153,7 @@ module Gen(P : Params) = struct
         in
         List.rev_append
           (Module.Name.Map.values modules)
-          (Module.Name.Map.values deprecated)
+          (Module.Name.Map.values wrapped_compat)
       in
       let virtual_library = Library.is_virtual lib in
       List.concat
diff --git a/src/lib_rules.ml b/src/lib_rules.ml
index 8f71bd7c..c35bfc44 100644
--- a/src/lib_rules.ml
+++ b/src/lib_rules.ml
@@ -120,19 +120,19 @@ module Gen (P : Install_rules.Params) = struct
       ~sandbox:alias_module_build_sandbox
       ~dep_graphs:(Ocamldep.Dep_graphs.dummy m)
 
-  let build_deprecated_modules (lib : Library.t)
+  let build_wrapped_compat_modules (lib : Library.t)
         cctx
         ~modules
         ~js_of_ocaml
         ~dynlink
-        ~(deprecated : Module.t Module.Name.Map.t) =
+        ~(wrapped_compat : Module.t Module.Name.Map.t) =
     let lib_name = String.capitalize (Lib_name.Local.to_string lib.name) in
     let transition_message =
       match lib.wrapped with
       | Simple _ -> "" (* will never be accessed anyway *)
       | Yes_with_transition r -> r
     in
-    Module.Name.Map.iteri deprecated ~f:(fun name m ->
+    Module.Name.Map.iteri wrapped_compat ~f:(fun name m ->
       let contents =
         let name = Module.Name.to_string name in
         let hidden_name = sprintf "%s__%s" lib_name name in
@@ -146,8 +146,8 @@ module Gen (P : Install_rules.Params) = struct
       |> SC.add_rule sctx
     );
     let dep_graphs =
-      Ocamldep.Dep_graphs.deprecated ~modules ~deprecated in
-    let cctx = Compilation_context.for_deprecated cctx deprecated in
+      Ocamldep.Dep_graphs.wrapped_compat ~modules ~wrapped_compat in
+    let cctx = Compilation_context.for_wrapped_compat cctx wrapped_compat in
     Module_compilation.build_modules cctx ~js_of_ocaml ~dynlink ~dep_graphs
 
   let build_c_file (lib : Library.t) ~scope ~dir ~includes (src, dst) =
@@ -323,7 +323,7 @@ module Gen (P : Install_rules.Params) = struct
     in
     let flags = SC.ocaml_flags sctx ~scope ~dir lib.buildable in
     let { Dir_contents.Library_modules.
-          modules; main_module_name; alias_module ; deprecated } =
+          modules; main_module_name; alias_module ; wrapped_compat } =
       Dir_contents.modules_of_library dir_contents ~name:(Library.best_name lib)
     in
     let source_modules = modules in
@@ -375,8 +375,8 @@ module Gen (P : Install_rules.Params) = struct
     in
     let js_of_ocaml = lib.buildable.js_of_ocaml in
 
-    build_deprecated_modules lib cctx ~dynlink ~js_of_ocaml
-      ~deprecated ~modules;
+    build_wrapped_compat_modules lib cctx ~dynlink ~js_of_ocaml
+      ~wrapped_compat ~modules;
 
     let dep_graphs = Ocamldep.rules cctx in
 
@@ -396,7 +396,7 @@ module Gen (P : Install_rules.Params) = struct
     in
     List.iter Cm_kind.all ~f:(fun cm_kind ->
       let files = add_cms ~cm_kind ~init:Path.Set.empty modules in
-      let files = add_cms ~cm_kind ~init:files deprecated in
+      let files = add_cms ~cm_kind ~init:files wrapped_compat in
       SC.Libs.setup_file_deps_alias sctx ~dir lib ~ext:(Cm_kind.ext cm_kind)
         files);
 
@@ -413,7 +413,7 @@ module Gen (P : Install_rules.Params) = struct
          else
            acc)
      in
-     let deprecated_modules = Module.Name.Map.values deprecated in
+     let deprecated_modules = Module.Name.Map.values wrapped_compat in
      (* deprecated modules have implementations so we can just append them *)
      let top_sorted_modules =
        Ocamldep.Dep_graph.top_closed_implementations dep_graphs.impl modules
diff --git a/src/ocamldep.ml b/src/ocamldep.ml
index 1a5d134d..268c75d7 100644
--- a/src/ocamldep.ml
+++ b/src/ocamldep.ml
@@ -52,14 +52,14 @@ module Dep_graph = struct
     ; per_module = Module.Name.Map.singleton m.name (Build.return [])
     }
 
-  let deprecated ~modules ~deprecated =
+  let wrapped_compat ~modules ~wrapped_compat =
     { dir = Path.root
-    ; per_module = Module.Name.Map.merge deprecated modules ~f:(fun _ d m ->
+    ; per_module = Module.Name.Map.merge wrapped_compat modules ~f:(fun _ d m ->
         match d, m with
         | None, None -> assert false
-        | Some deprecated, None ->
+        | Some wrapped_compat, None ->
           Exn.code_error "deprecated module needs counterpart"
-            [ "deprecated", Module.to_sexp deprecated
+            [ "deprecated", Module.to_sexp wrapped_compat
             ]
         | None, Some _ -> None
         | Some _, Some m -> Some (Build.return [m])
@@ -73,8 +73,8 @@ module Dep_graphs = struct
   let dummy m =
     Ml_kind.Dict.make_both (Dep_graph.dummy m)
 
-  let deprecated ~modules ~deprecated =
-    Ml_kind.Dict.make_both (Dep_graph.deprecated ~modules ~deprecated)
+  let wrapped_compat ~modules ~wrapped_compat =
+    Ml_kind.Dict.make_both (Dep_graph.wrapped_compat ~modules ~wrapped_compat)
 end
 
 let parse_module_names ~(unit : Module.t) ~modules words =
diff --git a/src/ocamldep.mli b/src/ocamldep.mli
index 83028590..184da31d 100644
--- a/src/ocamldep.mli
+++ b/src/ocamldep.mli
@@ -19,9 +19,9 @@ module Dep_graphs : sig
 
   val dummy : Module.t -> t
 
-  val deprecated
+  val wrapped_compat
     :  modules:Module.t Module.Name.Map.t
-    -> deprecated:Module.t Module.Name.Map.t
+    -> wrapped_compat:Module.t Module.Name.Map.t
     -> t
 end
 

From dfd3b1083c61cb45a0c17d2e1c77429c42b06bba Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Wed, 29 Aug 2018 22:19:48 +0300
Subject: [PATCH 08/17] Handle case when module alias exists

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 src/dir_contents.ml                                            | 3 ++-
 test/blackbox-tests/test-cases/wrapped-transition/lib/mylib.ml | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)
 create mode 100644 test/blackbox-tests/test-cases/wrapped-transition/lib/mylib.ml

diff --git a/src/dir_contents.ml b/src/dir_contents.ml
index 5401b8a3..8eb1aa3c 100644
--- a/src/dir_contents.ml
+++ b/src/dir_contents.ml
@@ -197,7 +197,8 @@ end = struct
       | Simple true -> (wrap_modules modules, Module.Name.Map.empty)
       | Yes_with_transition _ ->
         ( wrap_modules modules
-        , Module.Name.Map.map ~f:Module.deprecate modules
+        , Module.Name.Map.remove modules main_module_name
+          |> Module.Name.Map.map ~f:Module.deprecate
         )
     in
     let alias_module =
diff --git a/test/blackbox-tests/test-cases/wrapped-transition/lib/mylib.ml b/test/blackbox-tests/test-cases/wrapped-transition/lib/mylib.ml
new file mode 100644
index 00000000..54287077
--- /dev/null
+++ b/test/blackbox-tests/test-cases/wrapped-transition/lib/mylib.ml
@@ -0,0 +1,3 @@
+module Bar = Bar
+module Foo = Foo
+module Intf_only = Intf_only

From 366c102aa0b24236cd03ebc1281f8641289561fb Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Fri, 31 Aug 2018 11:25:01 +0300
Subject: [PATCH 09/17] Add .mli to one of transitioned modules

Somehow this removes the deprecation

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 test/blackbox-tests/test-cases/wrapped-transition/lib/foo.mli | 1 +
 test/blackbox-tests/test-cases/wrapped-transition/run.t       | 3 ---
 2 files changed, 1 insertion(+), 3 deletions(-)
 create mode 100644 test/blackbox-tests/test-cases/wrapped-transition/lib/foo.mli

diff --git a/test/blackbox-tests/test-cases/wrapped-transition/lib/foo.mli b/test/blackbox-tests/test-cases/wrapped-transition/lib/foo.mli
new file mode 100644
index 00000000..733b2a32
--- /dev/null
+++ b/test/blackbox-tests/test-cases/wrapped-transition/lib/foo.mli
@@ -0,0 +1 @@
+val run : unit -> unit
diff --git a/test/blackbox-tests/test-cases/wrapped-transition/run.t b/test/blackbox-tests/test-cases/wrapped-transition/run.t
index 76b1fea0..a59994bb 100644
--- a/test/blackbox-tests/test-cases/wrapped-transition/run.t
+++ b/test/blackbox-tests/test-cases/wrapped-transition/run.t
@@ -2,6 +2,3 @@
   File "fooexe.ml", line 3, characters 0-7:
   Error (warning 3): deprecated: module Bar
   Will be removed past 2020-20-20. Use Mylib.Bar instead.
-  File "fooexe.ml", line 4, characters 0-7:
-  Error (warning 3): deprecated: module Foo
-  Will be removed past 2020-20-20. Use Mylib.Foo instead.

From 161ca64030da8c2da09bab8ad90d5e15547e5938 Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Fri, 31 Aug 2018 13:10:59 +0300
Subject: [PATCH 10/17] Add Cm_kind.to_sexp conversion

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 src/cm_kind.ml  | 9 +++++++++
 src/cm_kind.mli | 4 ++++
 2 files changed, 13 insertions(+)

diff --git a/src/cm_kind.ml b/src/cm_kind.ml
index 0b52c7af..f2959463 100644
--- a/src/cm_kind.ml
+++ b/src/cm_kind.ml
@@ -1,3 +1,5 @@
+open Stdune
+
 type t = Cmi | Cmo | Cmx
 
 let all = [Cmi; Cmo; Cmx]
@@ -35,3 +37,10 @@ module Dict = struct
     ; cmx = x
     }
 end
+
+let to_sexp =
+  let open Sexp.To_sexp in
+  function
+  | Cmi -> string "cmi"
+  | Cmo -> string "cmo"
+  | Cmx -> string "cmx"
diff --git a/src/cm_kind.mli b/src/cm_kind.mli
index 71e8d087..ec8e4501 100644
--- a/src/cm_kind.mli
+++ b/src/cm_kind.mli
@@ -1,3 +1,5 @@
+open Stdune
+
 type t = Cmi | Cmo | Cmx
 
 val all : t list
@@ -5,6 +7,8 @@ val all : t list
 val ext : t -> string
 val source : t -> Ml_kind.t
 
+val to_sexp : t Sexp.To_sexp.t
+
 module Dict : sig
   type cm_kind = t
 

From ba1b3f8d2434f62c446303ce0b4efcd43d6c45b2 Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Fri, 31 Aug 2018 13:11:16 +0300
Subject: [PATCH 11/17] Set intf to None

deprecated modules don't really have interfaces

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 src/module.ml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/module.ml b/src/module.ml
index 2ef21c34..7c8639c5 100644
--- a/src/module.ml
+++ b/src/module.ml
@@ -166,7 +166,8 @@ let to_sexp { name; impl; intf; obj_name ; pp } =
 
 let deprecate t =
   { t with
-    impl =
+    intf = None
+  ; impl =
       Some (
         let path =
           match t.intf, t.impl with

From 868ecbc63254e4627bb6c514db0b8375942ffed5 Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Fri, 31 Aug 2018 13:50:07 +0300
Subject: [PATCH 12/17] Change deprecated modules in a separate directory

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 src/dir_contents.ml | 2 +-
 src/lib_rules.ml    | 6 +++---
 src/module.ml       | 8 +++++++-
 src/module.mli      | 2 +-
 src/stdune/path.ml  | 5 +++++
 src/stdune/path.mli | 4 ++++
 6 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/src/dir_contents.ml b/src/dir_contents.ml
index 8eb1aa3c..35a42df0 100644
--- a/src/dir_contents.ml
+++ b/src/dir_contents.ml
@@ -198,7 +198,7 @@ end = struct
       | Yes_with_transition _ ->
         ( wrap_modules modules
         , Module.Name.Map.remove modules main_module_name
-          |> Module.Name.Map.map ~f:Module.deprecate
+          |> Module.Name.Map.map ~f:Module.wrapped_compat
         )
     in
     let alias_module =
diff --git a/src/lib_rules.ml b/src/lib_rules.ml
index c35bfc44..4074fa07 100644
--- a/src/lib_rules.ml
+++ b/src/lib_rules.ml
@@ -413,13 +413,13 @@ module Gen (P : Install_rules.Params) = struct
          else
            acc)
      in
-     let deprecated_modules = Module.Name.Map.values wrapped_compat in
+     let wrapped_compat = Module.Name.Map.values wrapped_compat in
      (* deprecated modules have implementations so we can just append them *)
      let top_sorted_modules =
        Ocamldep.Dep_graph.top_closed_implementations dep_graphs.impl modules
-       >>^ fun modules -> modules @ deprecated_modules
+       >>^ fun modules -> modules @ wrapped_compat
      in
-     (let modules = modules @ deprecated_modules in
+     (let modules = modules @ wrapped_compat in
         List.iter Mode.all ~f:(fun mode ->
        build_lib lib ~scope ~flags ~dir ~obj_dir ~mode ~top_sorted_modules
          ~modules)));
diff --git a/src/module.ml b/src/module.ml
index 7c8639c5..bb19fb20 100644
--- a/src/module.ml
+++ b/src/module.ml
@@ -164,7 +164,7 @@ let to_sexp { name; impl; intf; obj_name ; pp } =
     ; "pp", (option string) (Option.map ~f:(fun _ -> "has pp") pp)
     ]
 
-let deprecate t =
+let wrapped_compat t =
   { t with
     intf = None
   ; impl =
@@ -176,6 +176,12 @@ let deprecate t =
           | Some intf, _ -> intf.path
           | None, None -> assert false
         in
+        let path =
+          Path.L.relative (Path.parent_exn path)
+            [ ".wrapped_compat"
+            ; Path.basename path
+            ]
+        in
         let (base, _) = Path.split_extension path in
         { syntax = OCaml
         ; path = Path.extend_basename base ~suffix:".ml-gen"
diff --git a/src/module.mli b/src/module.mli
index 4e3201da..fec3aa25 100644
--- a/src/module.mli
+++ b/src/module.mli
@@ -95,4 +95,4 @@ val set_pp : t -> (unit, string list) Build.t option -> t
 
 val to_sexp : t Sexp.To_sexp.t
 
-val deprecate : t -> t
+val wrapped_compat : t -> t
diff --git a/src/stdune/path.ml b/src/stdune/path.ml
index c277df2f..e832c76a 100644
--- a/src/stdune/path.ml
+++ b/src/stdune/path.ml
@@ -943,3 +943,8 @@ module Internal = struct
     | In_source_tree l -> Local l
     | External l -> External l
 end
+
+module L = struct
+  (* TODO more efficient implementation *)
+  let relative t = List.fold_left ~init:t ~f:relative
+end
diff --git a/src/stdune/path.mli b/src/stdune/path.mli
index 6880fa24..3da71c48 100644
--- a/src/stdune/path.mli
+++ b/src/stdune/path.mli
@@ -169,3 +169,7 @@ val set_root : External.t -> unit
 module Internal : sig
   val raw_kind : t -> Kind.t
 end
+
+module L : sig
+  val relative : t -> string list -> t
+end

From 96e3448228d647c698500de8e6a0a6026097131f Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Fri, 31 Aug 2018 14:03:25 +0300
Subject: [PATCH 13/17] Add documentation and change log entry

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 CHANGES.md         | 4 ++++
 doc/dune-files.rst | 7 +++++++
 2 files changed, 11 insertions(+)

diff --git a/CHANGES.md b/CHANGES.md
index 40596326..91d298c8 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -38,6 +38,10 @@ next
 
 - Improve message suggesting to remove parentheses (#1196, fix #1173, @emillon)
 
+- Add `(wrapped (transition "..message.."))` as an option that will generate
+  wrapped modules but keep unwrapped modules with a deprecation message to
+  preserve compatibility. (#1188, fix #985, @rgrinberg)
+
 1.1.1 (08/08/2018)
 ------------------
 
diff --git a/doc/dune-files.rst b/doc/dune-files.rst
index 3c2915ee..ce87c4dc 100644
--- a/doc/dune-files.rst
+++ b/doc/dune-files.rst
@@ -96,6 +96,13 @@ to use the :ref:`include_subdirs` stanza.
   only intended for libraries that manually prefix all their modules by the
   library name and to ease porting of existing projects to dune
 
+- ``(wrapped (transition <message>))`` Is the same as ``(wrapped true)`` except
+  that it will also generate unwrapped (not prefixed by the library name)
+  modules to preserve compatibility. This is useful for libraries that would
+  like to transition from ``(wrapped false)`` to ``(wrapped true)`` without
+  breaking compatibility for users. The ``<message>`` will be included in the
+  deprecation notice for the unwrapped modules.
+
 - ``(preprocess <preprocess-spec>)`` specifies how to preprocess files if
   needed. The default is ``no_processing``. Other options are described in the
   `Preprocessing specification`_ section

From 8449b46bc1eaecce2f9eb742119ee3ba2ea528b9 Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Fri, 31 Aug 2018 15:47:43 +0300
Subject: [PATCH 14/17] Fix tests

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 test/blackbox-tests/test-cases/wrapped-transition/run.t | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/test/blackbox-tests/test-cases/wrapped-transition/run.t b/test/blackbox-tests/test-cases/wrapped-transition/run.t
index a59994bb..fda4cc0b 100644
--- a/test/blackbox-tests/test-cases/wrapped-transition/run.t
+++ b/test/blackbox-tests/test-cases/wrapped-transition/run.t
@@ -2,3 +2,9 @@
   File "fooexe.ml", line 3, characters 0-7:
   Error (warning 3): deprecated: module Bar
   Will be removed past 2020-20-20. Use Mylib.Bar instead.
+  File "fooexe.ml", line 4, characters 0-7:
+  Error (warning 3): deprecated: module Foo
+  Will be removed past 2020-20-20. Use Mylib.Foo instead.
+  File "fooexe.ml", line 7, characters 11-22:
+  Error (warning 3): deprecated: module Intf_only
+  Will be removed past 2020-20-20. Use Mylib.Intf_only instead.

From 28b311cf95486154a25cbb2d1884c8e6d80a57f2 Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Fri, 31 Aug 2018 17:45:42 +0300
Subject: [PATCH 15/17] Clarifying comment about appending wrapped compat
 modules

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 src/lib_rules.ml | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/lib_rules.ml b/src/lib_rules.ml
index 4074fa07..976819a6 100644
--- a/src/lib_rules.ml
+++ b/src/lib_rules.ml
@@ -414,7 +414,9 @@ module Gen (P : Install_rules.Params) = struct
            acc)
      in
      let wrapped_compat = Module.Name.Map.values wrapped_compat in
-     (* deprecated modules have implementations so we can just append them *)
+     (* Compatibility modules have implementations so we can just append them.
+        We append the modules at the end as no library modules depend on
+        them. *)
      let top_sorted_modules =
        Ocamldep.Dep_graph.top_closed_implementations dep_graphs.impl modules
        >>^ fun modules -> modules @ wrapped_compat

From 18abaa7def18b5320c0ac10bfba7fde688d444ca Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Fri, 31 Aug 2018 17:52:44 +0300
Subject: [PATCH 16/17] Simplify code using Module.dir

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 src/module.ml | 20 +++++---------------
 1 file changed, 5 insertions(+), 15 deletions(-)

diff --git a/src/module.ml b/src/module.ml
index bb19fb20..26fd5fc0 100644
--- a/src/module.ml
+++ b/src/module.ml
@@ -169,22 +169,12 @@ let wrapped_compat t =
     intf = None
   ; impl =
       Some (
-        let path =
-          match t.intf, t.impl with
-          | Some _, Some impl
-          | None, Some impl -> impl.path
-          | Some intf, _ -> intf.path
-          | None, None -> assert false
-        in
-        let path =
-          Path.L.relative (Path.parent_exn path)
-            [ ".wrapped_compat"
-            ; Path.basename path
-            ]
-        in
-        let (base, _) = Path.split_extension path in
         { syntax = OCaml
-        ; path = Path.extend_basename base ~suffix:".ml-gen"
+        ; path =
+          Path.L.relative (dir t)
+            [ ".wrapped_compat"
+            ; Name.to_string t.name ^ ".ml-gen"
+            ]
         }
       )
   }

From 3c89b6c131e056dd7cf04a008191107e049bb928 Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <rudi.grinberg@gmail.com>
Date: Fri, 31 Aug 2018 17:58:58 +0300
Subject: [PATCH 17/17] Require dune lang 1.2 for transitioning wraps

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>
---
 src/dune_file.ml | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/dune_file.ml b/src/dune_file.ml
index 924d42a6..d2116fcf 100644
--- a/src/dune_file.ml
+++ b/src/dune_file.ml
@@ -868,7 +868,9 @@ module Library = struct
       sum
         [ "true", return (Simple true)
         ; "false", return (Simple false)
-        ; "transition", string >>| fun x -> Yes_with_transition x
+        ; "transition",
+          Syntax.since Stanza.syntax (1, 2) >>= fun () ->
+          string >>| fun x -> Yes_with_transition x
         ]
 
     let field = field "wrapped" ~default:(Simple true) dparse