fix error message in Main

src/driver/driver.ml

@@ -267,7 +267,6 @@ let prepare_task drv task =
   let task = update_task drv task in
   List.fold_left apply task transl
 
-
 let print_task_prepared ?old drv fmt task =
   let p = match drv.drv_printer with
     | None -> raise NoPrinter
@@ -278,7 +277,6 @@ let print_task_prepared ?old drv fmt task =
   in
   fprintf fmt "@[%a@]@?" (printer ?old) task
 
-
 let print_task ?old drv fmt task =
   let task = prepare_task drv task in
   print_task_prepared ?old drv fmt task
@@ -291,7 +289,6 @@ let prove_task_prepared ~command ?timelimit ?memlimit ?old drv task =
   Buffer.reset buf;
   res
 
-
 let prove_task ~command ?timelimit ?memlimit ?old drv task =
   let task = prepare_task drv task in
   prove_task_prepared ~command ?timelimit ?memlimit ?old drv task

src/main.ml

@@ -342,7 +342,8 @@ let () = try
   begin match !opt_prover with
   | Some s ->
       let prover = try Mstr.find s (get_provers config) with
-        | Not_found -> eprintf "Driver %s not found.@." s; exit 1
+        | Not_found -> eprintf "Prover '%s' not found in %s@."
+            s (Whyconf.get_conf_file config); exit 1
       in
       opt_command := Some prover.command;
       opt_driver := Some prover.driver