error: duplicate item `dup` in service `Service1`
  --> test/ui/duplicate_service_item.aldrin:7:8
   |
 7 |     fn dup = fallback;
   |        ^^^ duplicate defined here
   |
  ::: test/ui/duplicate_service_item.aldrin:5:8
   |
 5 |     fn dup @ 1;
   |        --- first defined here
   |
