error[E0116]: cannot define inherent `impl` for a type outside of the crate where the type is defined --> $DIR/E0116.rs:1:1 | LL | impl Vec {} | ^^^^^^^^^^^^ impl for type defined outside of crate. | = note: define and implement a trait or new type instead error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0116`.