| There are both a positive and negative trait implementation for the same type. | |
| Erroneous code example: | |
| ```compile_fail,E0751 | |
| trait MyTrait {} | |
| impl MyTrait for i32 { } | |
| impl !MyTrait for i32 { } // error! | |
| ``` | |
| Negative implementations are a promise that the trait will never be implemented | |
| for the given types. Therefore, both cannot exists at the same time. |