1 error[E0232]: `#[rustc_on_unimplemented]` requires a value
4 LL | #[rustc_on_unimplemented]
5 | ^^^^^^^^^^^^^^^^^^^^^^^^^ value required here
7 = note: eg `#[rustc_on_unimplemented(message="foo")]`
9 error: aborting due to previous error
11 For more information about this error, try `rustc --explain E0232`.