error: attribute must be of the form `#[repr(C, packed, ...)]`
  --> $DIR/repr.rs:1:1
   |
LL | #[repr]
   | ^^^^^^^

error: attribute must be of the form `#[repr(C, packed, ...)]`
  --> $DIR/repr.rs:5:1
   |
LL | #[repr = "B"]
   | ^^^^^^^^^^^^^

error: attribute must be of the form `#[repr(C, packed, ...)]`
  --> $DIR/repr.rs:9:1
   |
LL | #[repr = "C"]
   | ^^^^^^^^^^^^^

error: aborting due to 3 previous errors