error: duplicate variant `Var` in enum `Enum`
  --> test/ui/duplicate_enum_variant.aldrin:4:5
   |
 4 |     Var = fallback;
   |     ^^^ duplicate defined here
   |
  ::: test/ui/duplicate_enum_variant.aldrin:2:5
   |
 2 |     Var @ 1;
   |     -------- first defined here
   |
