feature: add locations to dependencies

This improves the error messages for the unused libray check

Signed-off-by: Rudi Grinberg <me@rgrinberg.com>

Author: rgrinberg

bin/describe/describe_workspace.ml

@@ -428,7 +428,9 @@ module Crawl = struct
       let+ requires =
         let* compile_info = Exe_rules.compile_info ~scope exes in
         let open Resolve.Memo.O in
-        let* requires = Lib.Compile.direct_requires compile_info in
+        let* requires =
+          Lib.Compile.direct_requires compile_info |> Resolve.Memo.map ~f:Loc.L.drop
+        in
         if options.with_pps
         then
           let+ pps = Lib.Compile.pps compile_info in

otherlibs/stdune/src/loc.ml

@@ -159,3 +159,8 @@ let rec render ppf pp =
   Pp.to_fmt_with_tags ppf pp ~tag_handler:(fun ppf Loc pp ->
     Format.fprintf ppf "@{<loc>%a@}" render pp)
 ;;
+
+module L = struct
+  let drop x = List.map ~f:snd x
+  let add_none x = List.map ~f:(fun x -> none, x) x
+end

otherlibs/stdune/src/loc.mli

@@ -27,3 +27,11 @@ val on_same_line : t -> t -> bool
 val compare : t -> t -> Ordering.t
 val span : t -> t -> t
 val set_start_to_stop : t -> t
+
+module L : sig
+  type loc := t
+  type 'a t := (loc * 'a) list
+
+  val drop : 'a t -> 'a list
+  val add_none : 'a list -> 'a t
+end

src/dune_rules/bootstrap_info.ml

@@ -62,7 +62,9 @@ let include_subdirs dir_contents =
 let make_root_module sctx ~name compile_info =
   let open Action_builder.O in
   let+ entries =
-    let requires_compile = Lib.Compile.direct_requires compile_info in
+    let requires_compile =
+      Lib.Compile.direct_requires compile_info |> Resolve.Memo.map ~f:Loc.L.drop
+    in
     Root_module.entries sctx ~requires_compile
   in
   { Root_module_data.name; entries }

src/dune_rules/cinaps.ml

@@ -163,7 +163,9 @@ let gen_rules sctx t ~dir ~scope =
         in
         Pp_spec.pp_module preprocess module_ >>| Modules.With_vlib.singleton_exe
       in
-      let requires_compile = Lib.Compile.direct_requires compile_info in
+      let requires_compile =
+        Lib.Compile.direct_requires compile_info |> Resolve.Memo.map ~f:Loc.L.drop
+      in
       let requires_link = Lib.Compile.requires_link compile_info in
       let obj_dir = Obj_dir.make_exe ~dir:cinaps_dir ~name in
       Compilation_context.create

src/dune_rules/exe_rules.ml

@@ -182,7 +182,9 @@ let executables_rules
   in
   let programs = programs ~modules ~exes in
   let* cctx =
-    let requires_compile = Lib.Compile.direct_requires compile_info in
+    let requires_compile =
+      Lib.Compile.direct_requires compile_info |> Resolve.Memo.map ~f:Loc.L.drop
+    in
     let requires_link = Lib.Compile.requires_link compile_info in
     let instances =
       Parameterised_rules.instances ~sctx ~db:(Scope.libs scope) exes.buildable.libraries