Improve dependency path printing

src/build_system.ml

@@ -142,18 +142,11 @@ module Build_error = struct
     raise (E { backtrace; dep_path; exn })
 end
 
-let describe_target fn =
-  match Path.extract_build_context fn with
-  | Some (".aliases", dir) ->
-    sprintf "alias %s" (Path.to_string dir)
-  | _ ->
-    Path.to_string fn
-
 let wait_for_file t fn ~targeting =
   match Hashtbl.find t.files fn with
   | None ->
     if Path.is_in_build_dir fn then
-      die "no rule found for %s" (describe_target fn)
+      die "no rule found for %s" (Utils.describe_target fn)
     else if Path.exists fn then
       return ()
     else

src/main.ml

@@ -124,7 +124,7 @@ let report_error ?map_fname ppf exn =
     if !Clflags.debug_dep_path then
       Format.fprintf ppf "Dependency path:\n    %s\n"
         (String.concat ~sep:"\n--> "
-           (List.map (E.dependency_path err) ~f:Path.to_string))
+           (List.map (E.dependency_path err) ~f:Utils.describe_target))
   | exn ->
     let backtrace = Printexc.get_raw_backtrace () in
     report_error ?map_fname ppf exn ~backtrace

src/utils.ml

@@ -66,3 +66,10 @@ let jbuild_name_in ~dir =
     sprintf "%s (context %s)"
       (Path.to_string (Path.relative dir "jbuild"))
       ctx_name
+
+let describe_target fn =
+  match Path.extract_build_context fn with
+  | Some (".aliases", dir) ->
+    sprintf "alias %s" (Path.to_string dir)
+  | _ ->
+    Path.to_string fn

src/utils.mli

@@ -11,3 +11,6 @@ val signal_name : int -> string
 
 (** Return the path to the jbuild file in this directory as a string. *)
 val jbuild_name_in : dir:Path.t -> string
+
+(** Nice description of a target *)
+val describe_target : Path.t -> string

test/jbuild

@@ -23,4 +23,5 @@
   (deps ((files_recursively_in workspaces/github24)))
   (action
    (chdir workspaces/github24
-    (run ${exe:run.exe} ${bin:jbuilder} build @install --root .)))))
+    (run ${exe:run.exe} ${bin:jbuilder}
+     build @install --root . --debug-dependency-path)))))