derive may only be applied to structs, enums and unions error should only show once per derive

[Havvy]

The error `derive` may only be applied to structs, enums and unions currently fires for each derived trait in the attribute pointing at the trait it is implementing. It should instead fire once per attribute, pointing at the derive.

Minimal Code

#![allow(dead_code)]

#![derive(Debug, PartialEq, Eq)]
struct DerivedOn;

fn main() {}

Output

   Compiling playground v0.0.1 (file:///playground)
error: `derive` may only be applied to structs, enums and unions
 --> src/main.rs:3:29
  |
3 | #![derive(Debug, PartialEq, Eq)]
  |                             ^^

error: `derive` may only be applied to structs, enums and unions
 --> src/main.rs:3:18
  |
3 | #![derive(Debug, PartialEq, Eq)]
  |                  ^^^^^^^^^

error: `derive` may only be applied to structs, enums and unions
 --> src/main.rs:3:11
  |
3 | #![derive(Debug, PartialEq, Eq)]
  |           ^^^^^

error: aborting due to 3 previous errors

error: Could not compile `playground`.

To learn more, run the command again with --verbose.

Expected Output

   Compiling playground v0.0.1 (file:///playground)
error: `derive` may only be applied to structs, enums and unions
 --> src/main.rs:3:29
  |
3 | #![derive(Debug, PartialEq, Eq)]
  |    ^^^^^^

error: aborting due to 1 previous error

error: Could not compile `playground`.

To learn more, run the command again with --verbose.