error[E0732]: `#[repr(inttype)]` must be specified
  --> $DIR/arbitrary_enum_discriminant-no-repr.rs:4:1
   |
LL | / enum Enum {
LL | |
LL | |   Unit = 1,
LL | |   Tuple() = 2,
LL | |   Struct{} = 3,
LL | | }
   | |_^

error: aborting due to previous error

For more information about this error, try `rustc --explain E0732`.