| Drop was implemented on a trait, which is not allowed: only structs and |
| enums can implement Drop. |
| |
| Erroneous code example: |
| |
| ```compile_fail,E0120 |
| trait MyTrait {} |
| |
| impl Drop for MyTrait { |
| fn drop(&mut self) {} |
| } |
| ``` |
| |
| A workaround for this problem is to wrap the trait up in a struct, and implement |
| Drop on that: |
| |
| ``` |
| trait MyTrait {} |
| struct MyWrapper<T: MyTrait> { foo: T } |
| |
| impl <T: MyTrait> Drop for MyWrapper<T> { |
| fn drop(&mut self) {} |
| } |
| |
| ``` |
| |
| Alternatively, wrapping trait objects requires something: |
| |
| ``` |
| trait MyTrait {} |
| |
| //or Box<MyTrait>, if you wanted an owned trait object |
| struct MyWrapper<'a> { foo: &'a MyTrait } |
| |
| impl <'a> Drop for MyWrapper<'a> { |
| fn drop(&mut self) {} |
| } |
| ``` |
