[Libguestfs] [PATCH 1/6] dib: clear up "already provided" message

Improve the error message that is shown when trying to selecting an element, and another element provides it. This was implemented in diskimage-builder upstream as commit 452f7b8d5aaa6e85e3b01b970cd9cbc842b34b86. --- dib/elements.ml | 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7 deletions(-) diff --git a/dib/elements.ml b/dib/elements.ml index 95acca4..c6ca0ea 100644 --- a/dib/elements.ml +++ b/dib/elements.ml @@ -120,22 +120,36 @@ let load_dependencies elements loaded_elements = let queue = Queue.create () in let final = ref StringSet.empty in let provided = ref StringSet.empty in + let provided_by = Hashtbl.create 13 in List.iter (fun x -> Queue.push x queue) elements; final := stringset_of_list elements; while not (Queue.is_empty queue) do let elem = Queue.pop queue in if StringSet.mem elem !provided <> true then ( - let deps = get_deps elem in - provided := StringSet.union !provided (get_provides elem); + let element_deps = get_deps elem in + let element_provides = get_provides elem in + (* Save which elements provide another element for potential + * error message. + *) + StringSet.iter (fun x -> Hashtbl.add provided_by x elem) element_provides; + provided := StringSet.union !provided element_provides; StringSet.iter (fun x -> Queue.push x queue) - (StringSet.diff deps (StringSet.union !final !provided)); - final := StringSet.union !final deps + (StringSet.diff element_deps (StringSet.union !final !provided)); + final := StringSet.union !final element_deps ) done; let conflicts = StringSet.inter (stringset_of_list elements) !provided in - if not (StringSet.is_empty conflicts) then - error (f_"following elements were explicitly required but are provided by other included elements: %s") - (String.concat "," (StringSet.elements conflicts)); + if not (StringSet.is_empty conflicts) then ( + let buf = Buffer.create 100 in + StringSet.iter ( + fun elem -> + let s = sprintf (f_" %s: already provided by %s") + elem (Hashtbl.find provided_by elem) in + Buffer.add_string buf s + ) conflicts; + error (f_"following elements are already provided by another element:\n%s") + (Buffer.contents buf) + ); if not (StringSet.mem "operating-system" !provided) then error (f_"please include an operating system element"); StringSet.diff !final !provided -- 2.9.3