Deprecate no_keep_locs

CHANGES.md

@@ -130,6 +130,10 @@ unreleased
 - Add `DUNE_PROFILE` environment variable to easily set the profile. (#1806,
   @rgrinberg)
 
+- Deprecate the undocumented `(no_keep_locs)` field. It was only
+  necessary until virtual libraries were supported (#1822, fix #1816,
+  @diml)
+
 1.6.2 (05/12/2018)
 ------------------
 

doc/dune-files.rst

@@ -200,8 +200,9 @@ to use the :ref:`include_subdirs` stanza.
 - ``(allow_overlapping_dependencies)`` allows external dependencies to
   overlap with libraries that are present in the workspace
 
-- ``(no_keep_locs)`` undocumented, it is a necessary hack until this
-  is implemented: https://github.com/ocaml/dune/issues/921
+- ``(no_keep_locs)`` does nothing. It used to be a necessary hack when
+  we were waiting for proper support for virtual libraries. Do not use
+  in new code, it will be deleted in dune 2.0
 
 Note that when binding C libraries, dune doesn't provide special support for
 tools such as ``pkg-config``, however it integrates easily with configurator_ by

src/dune_file.ml

@@ -837,6 +837,7 @@ module Library = struct
          located (field "self_build_stubs_archive" (option string) ~default:None)
        and no_dynlink = field_b "no_dynlink"
        and no_keep_locs = field_b "no_keep_locs"
+                            ~check:(Syntax.deprecated_in Stanza.syntax (1, 7))
        and sub_systems =
          return () >>= fun () ->
          Sub_system_info.record_parser ()

src/syntax.ml

@@ -101,6 +101,15 @@ module Error = struct
        | Some s -> ".\n" ^ s)
 end
 
+module Warning = struct
+  let deprecated_in loc t ?repl ver ~what =
+    Errors.warn loc "%s was deprecated in version %s of %s%s"
+      what (Version.to_string ver) t.desc
+      (match repl with
+       | None -> ""
+       | Some s -> ".\n" ^ s)
+end
+
 
 let create ~name ~desc supported_versions =
   { name
@@ -167,6 +176,16 @@ let deleted_in t ver =
     Error.deleted_in loc t ver ~what
   end
 
+let deprecated_in t ver =
+  let open Version.Infix in
+  get_exn t >>= fun current_ver ->
+  if current_ver < ver then
+    return ()
+  else begin
+    desc () >>| fun (loc, what) ->
+    Warning.deprecated_in loc t ver ~what;
+  end
+
 let renamed_in t ver ~to_ =
   let open Version.Infix in
   get_exn t >>= fun current_ver ->

src/syntax.mli

@@ -41,6 +41,16 @@ module Error : sig
     -> _
 end
 
+module Warning : sig
+  val deprecated_in
+    :  Loc.t
+    -> t
+    -> ?repl:string
+    -> Version.t
+    -> what:string
+    -> unit
+end
+
 (** [create ~name ~desc supported_versions] defines a new
     syntax. [supported_version] is the list of the last minor version
     of each supported major version. [desc] is used to describe what
@@ -63,6 +73,10 @@ val greatest_supported_version : t -> Version.t
     given version *)
 val deleted_in : t -> Version.t -> (unit, _) Dune_lang.Decoder.parser
 
+(** Indicate the field/constructor being parsed was deprecated in the
+    given version *)
+val deprecated_in : t -> Version.t -> (unit, _) Dune_lang.Decoder.parser
+
 (** Indicate the field/constructor being parsed was renamed in the
     given version *)
 val renamed_in : t -> Version.t -> to_:string ->  (unit, _) Dune_lang.Decoder.parser

test/blackbox-tests/test-cases/syntax-versioning/run.t

@@ -1,3 +1,5 @@
+  $ echo '(lang dune 1.0)' > dune-project
+
   $ echo '(jbuild_version 1)' > dune
   $ dune build
   File "dune", line 1, characters 0-18:
@@ -35,3 +37,16 @@
      ... %{x} ...
   [1]
   $ rm -f dune
+
+  $ echo '(lang dune 1.7)' > dune-project
+  $ cat > dune <<EOF
+  > (library
+  >  (name foo)
+  >  (no_keep_locs))
+  > EOF
+  $ dune build
+  File "dune", line 3, characters 1-15:
+  3 |  (no_keep_locs))
+       ^^^^^^^^^^^^^^
+  Warning: 'no_keep_locs' was deprecated in version 1.7 of the dune language
+  $ rm -f dune