| A `#[marker]` trait contained an associated item. | |
| Erroneous code example: | |
| ```compile_fail,E0714 | |
| #![feature(marker_trait_attr)] | |
| #![feature(associated_type_defaults)] | |
| #[marker] | |
| trait MarkerConst { | |
| const N: usize; // error! | |
| } | |
| fn main() {} | |
| ``` | |
| The items of marker traits cannot be overridden, so there's no need to have them | |
| when they cannot be changed per-type anyway. If you wanted them for ergonomic | |
| reasons, consider making an extension trait instead. |