Simplify the computing of version numbers

CHANGES.md

@@ -88,6 +88,10 @@
 
 - Include building stubs in `@check` rules. (@rgrinberg, #2530)
 
+- Get rid of ad-hoc rules for guessing the version. Dune now only
+  relies on the version written in the `dune-project` file and no
+  longer read `VERSION` or similar files (#2541, @diml)
+
 1.11.0 (23/07/2019)
 -------------------
 

doc/advanced-topics.rst

@@ -133,28 +133,22 @@ format is subject to change between versions.
 
 .. _Catapult trace-viewer: https://github.com/catapult-project/catapult/blob/master/tracing/README.md
 
+.. _package-version:
+
 Package version
 ===============
 
-Note that dune will try to determine the version number of packages
-defined in the workspace. While dune itself makes no use of version
-numbers, it can be use by external tools such as
-`ocamlfind <http://projects.camlcity.org/projects/findlib.html>`__.
-
-Dune determines the version of a package by trying the following
-methods in order:
-
-- it looks in the ``<package>.opam`` file for a ``version`` variable
-- it looks for a ``<package>.version`` file in the same directory and
-  reads the first line
-- it looks for the version specified in the ``dune-project`` if present
-- it looks for a ``version`` file and reads the first line
-- it looks for a ``VERSION`` file and reads the first line
-
-``<package>.version``, ``version`` and ``VERSION`` files may be
-generated.
-
-If the version can't be determined, dune just won't assign one.
+Dune determine the version of a package by looking at the ``version``
+field in the :ref:`package stanza <package>`. If the version field is
+not set, it looks at the toplevel ``version`` field in the
+``dune-project`` field. If neither are set, dune assume that we are in
+development mode and reads the version from the VCS if any. The way it
+obtains the version from the VCS in described in :ref:`the build-info
+section <build-info>`.
+
+When installing the files of a package on the system, dune
+automatically inserts the package version into various metadata files
+such as ``META`` and ``dune-package`` files.
 
 .. _ocaml-syntax:
 

doc/concepts.rst

@@ -190,7 +190,8 @@ In addition, ``(action ...)`` fields support the following special variables:
 
 - ``version:<package>`` expands to the version of the given
   package. Note that this is only supported for packages that are
-  being defined in the current scope
+  being defined in the current scope. How dune determines the version
+  of a package is described :ref:`here <package-version>`
 - ``read:<path>`` expands to the contents of the given file
 - ``read-lines:<path>`` expands to the list of lines in the given
   file

doc/dune-files.rst

@@ -211,6 +211,8 @@ defined in the project:
 
 - ``(documentation <url>)`` - Where the documentation is hosted
 
+.. _package:
+
 package
 -------
 

doc/dune-libs.rst

@@ -123,6 +123,8 @@ The following steps must be taken to transition from the old configurator:
 
 .. _pkg-config: https://www.freedesktop.org/wiki/Software/pkg-config/
 
+.. _build-info:
+
 build-info
 ==========
 

src/dune/build.ml

@@ -52,6 +52,8 @@ let arr f = Arr f
 
 let return x = Arr (fun _ -> x)
 
+let delayed = arr
+
 let record_lib_deps lib_deps = Record_lib_deps lib_deps
 
 module O = struct

src/dune/build.mli

@@ -52,6 +52,9 @@ val all : ('a, 'b) t list -> ('a, 'b list) t
     contains no targets. *)
 val lazy_no_targets : ('a, 'b) t Lazy.t -> ('a, 'b) t
 
+(** Delay a static computation until the arrow is evaluated *)
+val delayed : (unit -> 'a) -> (unit, 'a) t
+
 (* CR-someday diml: this API is not great, what about:
 
    {[ module Action_with_deps : sig type t val add_file_dependency : t ->

src/dune/dune_project.ml

@@ -773,8 +773,7 @@ let parse ~dir ~lang ~opam_packages ~file =
        match version with
        | None ->
            packages
-       | Some version ->
-           let version = Some (version, Package.Version_source.Project) in
+       | Some _ ->
            Package.Name.Map.map packages ~f:(fun p ->
                match p.version with Some _ -> p | None -> { p with version })
      in
@@ -915,11 +914,7 @@ let load ~dir ~files =
                          None
                    in
                    let* version = Opam_file.get_field opam "version" in
-                   match version with
-                   | String (_, s) ->
-                       Some (s, Package.Version_source.Package)
-                   | _ ->
-                       None
+                   match version with String (_, s) -> Some s | _ -> None
                  in
                  { Package.name
                  ; loc

src/dune/expander.ml

@@ -87,6 +87,19 @@ let expand_env t pform s : Value.t list option =
       else
         Some [ String (Option.value ~default (Env.get t.env var)) ]
 
+let expand_version scope pform s =
+  match
+    Package.Name.Map.find
+      (Dune_project.packages (Scope.project scope))
+      (Package.Name.of_string s)
+  with
+  | None ->
+      User_error.raise
+        ~loc:(String_with_vars.Var.loc pform)
+        [ Pp.textf "Package %S doesn't exist in the current project." s ]
+  | Some p -> (
+    match p.version with None -> [ Value.String "" ] | Some s -> [ String s ] )
+
 let expand_var_exn t var syn =
   t.expand_var t var syn
   |> Option.map ~f:(function
@@ -120,6 +133,8 @@ let make ~scope ~(context : Context.t) ~lib_artifacts ~bin_artifacts_host =
              Some (Ok (expand_ocaml_config (Lazy.force ocaml_config) var s))
          | Macro (Env, s) ->
              Option.map ~f:Result.ok (expand_env t var s)
+         | Macro (Version, s) ->
+             Some (Ok (expand_version scope var s))
          | Var Project_root ->
              Some (Ok [ Value.Dir (Path.build (Scope.root scope)) ])
          | expansion ->
@@ -234,12 +249,8 @@ let parse_lib_file ~loc s =
   | Some (lib, f) ->
       (Lib_name.of_string_exn ~loc:(Some loc) lib, f)
 
-type dynamic = { read_package : Package.t -> (unit, string option) Build.t }
-
-let error_expansion_kind = { read_package = (fun _ -> assert false) }
-
 type expansion_kind =
-  | Dynamic of dynamic
+  | Dynamic
   | Static
 
 let cc_of_c_flags t (cc : (unit, string list) Build.t C.Kind.Dict.t) =
@@ -254,7 +265,7 @@ let resolve_binary t ~loc ~prog =
   | Error e ->
       Error { Import.fail = (fun () -> Action.Prog.Not_found.raise e) }
 
-let expand_and_record acc ~map_exe ~dep_kind ~scope ~expansion_kind
+let expand_and_record acc ~map_exe ~dep_kind ~expansion_kind
     ~(dir : Path.Build.t) ~pform t expansion
     ~(cc : dir:Path.Build.t -> (unit, Value.t list) Build.t C.Kind.Dict.t) =
   let key = String_with_vars.Var.full_name pform in
@@ -268,12 +279,9 @@ let expand_and_record acc ~map_exe ~dep_kind ~scope ~expansion_kind
             [ Pp.textf "%s cannot be used in this position"
                 (String_with_vars.Var.describe pform)
             ]
-    | Dynamic _ ->
+    | Dynamic ->
         Resolved_forms.add_ddep acc ~key
   in
-  let { read_package } =
-    match expansion_kind with Static -> error_expansion_kind | Dynamic d -> d
-  in
   let open Build.O in
   match (expansion : Pform.Expansion.t) with
   | Var
@@ -284,7 +292,7 @@ let expand_and_record acc ~map_exe ~dep_kind ~scope ~expansion_kind
       | Target
       | Named_local
       | Values _ )
-  | Macro ((Ocaml_config | Env), _) ->
+  | Macro ((Ocaml_config | Env | Version), _) ->
       assert false
   | Var Cc ->
       add_ddep (cc ~dir).c
@@ -350,28 +358,6 @@ let expand_and_record acc ~map_exe ~dep_kind ~scope ~expansion_kind
       let path = relative dir s in
       let data = Build.strings path >>^ Value.L.strings in
       add_ddep data
-  | Macro (Version, s) -> (
-    match
-      Package.Name.Map.find
-        (Dune_project.packages (Scope.project scope))
-        (Package.Name.of_string s)
-    with
-    | Some p ->
-        let open Build.O in
-        let x =
-          read_package p
-          >>^ function None -> [ Value.String "" ] | Some s -> [ String s ]
-        in
-        add_ddep x
-    | None ->
-        Resolved_forms.add_fail acc
-          { fail =
-              (fun () ->
-                User_error.raise ~loc
-                  [ Pp.textf "Package %S doesn't exist in the current project."
-                      s
-                  ])
-          } )
 
 let check_multiplicity ~pform ~declaration ~use =
   let module Multiplicity = Dune_file.Rule.Targets.Multiplicity in
@@ -392,7 +378,7 @@ let check_multiplicity ~pform ~declaration ~use =
   | Multiple, One ->
       error "targets" "target"
 
-let expand_and_record_deps acc ~(dir : Path.Build.t) ~read_package ~dep_kind
+let expand_and_record_deps acc ~(dir : Path.Build.t) ~dep_kind
     ~targets_written_by_user ~map_exe ~expand_var ~cc t pform syntax_version =
   let res =
     let targets ~(multiplicity : Dune_file.Rule.Targets.Multiplicity.t) =
@@ -424,7 +410,8 @@ let expand_and_record_deps acc ~(dir : Path.Build.t) ~read_package ~dep_kind
              Some s
          | Error (expansion : Pform.Expansion.t) -> (
            match expansion with
-           | Var (Project_root | Values _) | Macro ((Ocaml_config | Env), _) ->
+           | Var (Project_root | Values _)
+           | Macro ((Ocaml_config | Env | Version), _) ->
                assert false (* these have been expanded statically *)
            | Var (First_dep | Deps | Named_local) ->
                None
@@ -433,8 +420,7 @@ let expand_and_record_deps acc ~(dir : Path.Build.t) ~read_package ~dep_kind
            | Var Target ->
                targets ~multiplicity:One
            | _ ->
-               expand_and_record acc ~map_exe ~dep_kind ~scope:t.scope
-                 ~expansion_kind:(Dynamic { read_package })
+               expand_and_record acc ~map_exe ~dep_kind ~expansion_kind:Dynamic
                  ~dir ~pform ~cc t expansion ))
   in
   Option.iter res ~f:(fun v ->
@@ -450,7 +436,7 @@ let expand_no_ddeps acc ~dir ~dep_kind ~map_exe ~expand_var ~cc t pform
          | Ok s ->
              Some s
          | Error (expansion : Pform.Expansion.t) ->
-             expand_and_record acc ~map_exe ~dep_kind ~scope:t.scope ~cc
+             expand_and_record acc ~map_exe ~dep_kind ~cc
                ~expansion_kind:Static ~dir ~pform t expansion)
   in
   Option.iter res ~f:(fun v ->
@@ -474,8 +460,8 @@ let gen_with_record_deps ~expand t resolved_forms ~dep_kind ~map_exe
   in
   { t with expand_var; bindings }
 
-let with_record_deps t resolved_forms ~read_package ~targets_written_by_user =
-  let expand = expand_and_record_deps ~read_package ~targets_written_by_user in
+let with_record_deps t resolved_forms ~targets_written_by_user =
+  let expand = expand_and_record_deps ~targets_written_by_user in
   gen_with_record_deps ~expand t resolved_forms
 
 let with_record_no_ddeps = gen_with_record_deps ~expand:expand_no_ddeps

src/dune/expander.mli

@@ -89,7 +89,6 @@ end
 val with_record_deps :
      t
   -> Resolved_forms.t
-  -> read_package:(Package.t -> (unit, string option) Build.t)
   -> targets_written_by_user:Targets.t
   -> dep_kind:Lib_deps_info.Kind.t
   -> map_exe:(Path.t -> Path.t)