warning: variant `Void` is never constructed
  --> $DIR/derive-uninhabited-enum-38885.rs:13:5
   |
LL | enum Foo {
   |      --- variant in this enum
LL |     Bar(u8),
LL |     Void(Void),
   |     ^^^^
   |
   = note: `Foo` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
   = note: `-W dead-code` implied by `-W unused`

warning: 1 warning emitted

