suggest removing ; after derive attribute in case of error

[matthiaskrgr]

Given the following code:

#[derive(Debug, Clone)];
struct Todo {
    item: String,
}

The current output is:

error: expected item after attributes
 --> src/main.rs:5:1
  |
5 | #[derive(Debug, Clone)];
  | ^^^^^^^^^^^^^^^^^^^^^^^

Ideally the output should look like:

Rust could point at the semicolon (which causes the error) and suggest removing it in this case.

[nerandell]

@rustbot claim