error[E0117]: only traits defined in the current crate can be implemented for primitive types --> $DIR/E0117.rs:1:1 | LL | impl Drop for u32 {} | ^^^^^^^^^^^^^^--- | | | | | `u32` is not defined in the current crate | impl doesn't use only types from inside the current crate | = note: define and implement a trait or new type instead error[E0120]: the `Drop` trait may only be implemented for local structs, enums, and unions --> $DIR/E0117.rs:1:15 | LL | impl Drop for u32 {} | ^^^ must be a struct, enum, or union in the current crate error: aborting due to 2 previous errors Some errors have detailed explanations: E0117, E0120. For more information about an error, try `rustc --explain E0117`.