error: can only derive `Countable` for `enum`s with `repr(u8)`
 --> tests/countable/enum_fields.rs:4:1
  |
4 | / enum Tag {
5 | |     X(u8),
6 | |     Y(u32),
7 | | }
  | |_^

error: can only derive `Countable` for fieldless `enum`s
 --> tests/countable/enum_fields.rs:5:6
  |
5 |     X(u8),
  |      ^^^^

error: can only derive `Countable` for fieldless `enum`s
 --> tests/countable/enum_fields.rs:6:6
  |
6 |     Y(u32),
  |      ^^^^^