error[E0412]: cannot find type `Nonexistent` in this scope --> $DIR/drop-on-non-struct.rs:9:15 | LL | impl Drop for Nonexistent { | ^^^^^^^^^^^ not found in this scope error[E0117]: only traits defined in the current crate can be implemented for arbitrary types --> $DIR/drop-on-non-struct.rs:1:1 | LL | impl<'a> Drop for &'a mut isize { | ^^^^^^^^^^^^^^^^^^------------- | | | | | `isize` 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/drop-on-non-struct.rs:1:19 | LL | impl<'a> Drop for &'a mut isize { | ^^^^^^^^^^^^^ must be a struct, enum, or union in the current crate error: aborting due to 3 previous errors Some errors have detailed explanations: E0117, E0120, E0412. For more information about an error, try `rustc --explain E0117`.