error[E0517]: attribute should be applied to a struct, enum, or union
  --> $DIR/repr-disallow-on-variant.rs:4:12
   |
LL |     #[repr(u8)]
   |            ^^
LL |
LL |     Variant,
   |     ------- not a struct, enum, or union

error: aborting due to previous error

For more information about this error, try `rustc --explain E0517`.