Do not use the transitive closure in generated META files

CHANGES.md

@@ -33,6 +33,9 @@ next
   [opam-cross-windows](https://github.com/whitequark/opam-cross-windows)
   (#355)
 
+- Simplify generated META files: do not generate the transitive
+  closure of dependencies in META files (#405)
+
 1.0+beta16 (05/11/2017)
 -----------------------
 

src/gen_meta.ml

@@ -1,7 +1,6 @@
 open Import
 open Jbuild
 open Meta
-open Build.O
 
 module Pub_name = struct
   type t =
@@ -121,7 +120,7 @@ let gen_lib pub_name (lib : Library.t) ~lib_deps ~ppx_runtime_deps:ppx_rt_deps ~
       )
     ]
 
-let gen ~package ~version ~stanzas ~lib_deps ~ppx_runtime_deps =
+let gen ~package ~version ~stanzas ~resolve_lib_dep_names =
   let items =
     List.filter_map stanzas ~f:(fun (dir, stanza) ->
       match (stanza : Stanza.t) with
@@ -131,20 +130,21 @@ let gen ~package ~version ~stanzas ~lib_deps ~ppx_runtime_deps =
       | _ ->
         None)
   in
-  (version >>^ function
-   | None -> []
-   | Some s -> [rule "version" [] Set s])
-  >>>
-  Build.all
-    (List.map items ~f:(fun (Lib (dir, pub_name, lib)) ->
-         Build.fanout3
-           (Build.arr (fun x -> x))
-           (lib_deps ~dir         (Stanza.Library lib))
-           (ppx_runtime_deps ~dir (Stanza.Library lib))
-         >>^ fun (version, lib_deps, ppx_runtime_deps) ->
-         (pub_name,
-          gen_lib pub_name lib ~lib_deps ~ppx_runtime_deps ~version)))
-  >>^ fun pkgs ->
+  let version =
+    match version with
+    | None -> []
+    | Some s -> [rule "version" [] Set s]
+  in
+  let pkgs =
+    List.map items ~f:(fun (Lib (dir, pub_name, lib)) ->
+      let lib_deps = resolve_lib_dep_names ~dir lib.buildable.libraries in
+      let ppx_runtime_deps =
+        resolve_lib_dep_names ~dir
+          (List.map lib.ppx_runtime_libraries ~f:Lib_dep.direct)
+      in
+      (pub_name,
+       gen_lib pub_name lib ~lib_deps ~ppx_runtime_deps ~version))
+  in
   let pkgs =
     List.map pkgs ~f:(fun (pn, meta) ->
       match Pub_name.to_list pn with

src/gen_meta.mli

@@ -4,12 +4,7 @@ open! Import
 
 val gen
   :  package:string
-  -> version:(unit, string option) Build.t
+  -> version:string option
   -> stanzas:(Path.t * Jbuild.Stanza.t) list
-  -> lib_deps:(dir:Path.t
-               -> Jbuild.Stanza.t
-               -> (Meta.entry list, string list) Build.t)
-  -> ppx_runtime_deps:(dir:Path.t
-                       -> Jbuild.Stanza.t
-                       -> (Meta.entry list, string list) Build.t)
-  -> (unit, Meta.t) Build.t
+  -> resolve_lib_dep_names:(dir:Path.t -> Jbuild.Lib_dep.t list -> string list)
+  -> Meta.t

src/gen_rules.ml

@@ -881,31 +881,11 @@ Add it to your jbuild file to remove this warning.
           Build.return ["# JBUILDER_GEN"]
       in
       let meta =
+        version >>^ fun version ->
         Gen_meta.gen ~package:pkg.name
           ~version
           ~stanzas:(SC.stanzas_to_consider_for_install sctx)
-          ~lib_deps:(fun ~dir jbuild ->
-            match jbuild with
-            | Library lib ->
-              Build.arr ignore
-              >>>
-              SC.Libs.load_requires sctx ~dir ~item:lib.name
-              >>^ List.map ~f:Lib.best_name
-            | Executables exes ->
-              let item = List.hd exes.names in
-              Build.arr ignore
-              >>>
-              SC.Libs.load_requires sctx ~dir ~item
-              >>^ List.map ~f:Lib.best_name
-            | _ -> Build.arr (fun _ -> []))
-          ~ppx_runtime_deps:(fun ~dir jbuild ->
-            match jbuild with
-            | Library lib ->
-              Build.arr ignore
-              >>>
-              SC.Libs.load_runtime_deps sctx ~dir ~item:lib.name
-              >>^ List.map ~f:Lib.best_name
-            | _ -> Build.arr (fun _ -> []))
+          ~resolve_lib_dep_names:(SC.Libs.best_lib_dep_names_exn sctx)
       in
       SC.add_rule sctx
         (Build.fanout meta template

src/lib_db.ml

@@ -144,33 +144,36 @@ let create findlib ~scopes internal_libraries =
 let internal_libs_without_non_installable_optional_ones t =
   String_map.values t.instalable_internal_libs
 
+let interpret_lib_dep t ~dir lib_dep =
+  match lib_dep with
+  | Lib_dep.Direct name -> begin
+      match find_exn t ~from:dir name with
+      | x -> Inl [x]
+      | exception e ->
+        (* Call [find] again to get a proper backtrace *)
+        Inr { fail = fun () -> ignore (find_exn t ~from:dir name : Lib.t); raise e }
+    end
+  | Select { choices; loc; _ } ->
+    match
+      List.find_map choices ~f:(fun { required; forbidden; _ } ->
+        if String_set.exists forbidden ~f:(lib_is_available t ~from:dir) then
+          None
+        else
+          match
+            List.map (String_set.elements required) ~f:(find_exn t ~from:dir)
+          with
+          | l           -> Some l
+          | exception _ -> None)
+    with
+    | Some l -> Inl l
+    | None ->
+      Inr { fail = fun () ->
+        Loc.fail loc "No solution found for this select form"
+      }
+
 let interpret_lib_deps t ~dir lib_deps =
   let libs, failures =
-    List.partition_map lib_deps ~f:(function
-      | Lib_dep.Direct name -> begin
-          match find_exn t ~from:dir name with
-          | x -> Inl [x]
-          | exception e ->
-            (* Call [find] again to get a proper backtrace *)
-            Inr { fail = fun () -> ignore (find_exn t ~from:dir name : Lib.t); raise e }
-        end
-      | Select { choices; loc; _ } ->
-        match
-          List.find_map choices ~f:(fun { required; forbidden; _ } ->
-            if String_set.exists forbidden ~f:(lib_is_available t ~from:dir) then
-              None
-            else
-              match
-                List.map (String_set.elements required) ~f:(find_exn t ~from:dir)
-              with
-              | l           -> Some l
-              | exception _ -> None)
-        with
-        | Some l -> Inl l
-        | None ->
-          Inr { fail = fun () ->
-            Loc.fail loc "No solution found for this select form"
-          })
+    List.partition_map lib_deps ~f:(interpret_lib_dep t ~dir)
   in
   let internals, externals =
     List.partition_map (List.concat libs) ~f:(function
@@ -182,6 +185,12 @@ let interpret_lib_deps t ~dir lib_deps =
    | [] -> None
    | f :: _ -> Some f)
 
+let best_lib_dep_names_exn t ~dir lib_deps =
+  List.concat_map lib_deps ~f:(fun lib_dep ->
+    match interpret_lib_dep t ~dir lib_dep with
+    | Inl libs -> List.map libs ~f:Lib.best_name
+    | Inr fail -> fail.fail ())
+
 type resolved_select =
   { src_fn : string
   ; dst_fn : string

src/lib_db.mli

@@ -24,6 +24,12 @@ val interpret_lib_deps
   -> Jbuild.Lib_dep.t list
   -> Lib.Internal.t list * Findlib.package list * fail option
 
+val best_lib_dep_names_exn
+  :  t
+  -> dir:Path.t
+  -> Jbuild.Lib_dep.t list
+  -> string list
+
 type resolved_select =
   { src_fn : string
   ; dst_fn : string

src/super_context.ml

@@ -256,6 +256,8 @@ module Libs = struct
 
   let find t ~from name = find t.libs ~from name
 
+  let best_lib_dep_names_exn t ~dir deps = best_lib_dep_names_exn t.libs ~dir deps
+
   let vrequires t ~dir ~item =
     let fn = Path.relative dir (item ^ ".requires.sexp") in
     Build.Vspec.T (fn, t.libs_vfile)

src/super_context.mli

@@ -77,6 +77,7 @@ val unique_library_name : t -> Lib.t -> string
 
 module Libs : sig
   val find : t -> from:Path.t -> string -> Lib.t option
+  val best_lib_dep_names_exn : t -> dir:Path.t -> Lib_dep.t list -> string list
 
   val load_requires     : t -> dir:Path.t -> item:string -> (unit, Lib.t list) Build.t
   val load_runtime_deps : t -> dir:Path.t -> item:string -> (unit, Lib.t list) Build.t

test/blackbox-tests/test-cases/meta-gen/run.t

@@ -17,17 +17,17 @@
   package "rewriter" (
     directory = "rewriter"
     description = "ppx rewriter"
-    requires(ppx_driver) = "bytes foobar"
+    requires(ppx_driver) = "foobar"
     archive(ppx_driver,byte) = "foobar_rewriter.cma"
     archive(ppx_driver,native) = "foobar_rewriter.cmxa"
     plugin(ppx_driver,byte) = "foobar_rewriter.cma"
     plugin(ppx_driver,native) = "foobar_rewriter.cmxs"
     # This is what jbuilder uses to find out the runtime dependencies of
     # a preprocessor
-    ppx_runtime_deps = "bytes foobar.baz"
+    ppx_runtime_deps = "foobar.baz"
     # This line makes things transparent for people mixing preprocessors
     # and normal dependencies
-    requires(-ppx_driver) = "bytes foobar.baz"
+    requires(-ppx_driver) = "foobar.baz"
     ppx(-ppx_driver,-custom_ppx) = "./ppx.exe --as-ppx"
   )
   package "sub" (