| error[E0373]: closure may outlive the current function, but it borrows `books`, which is owned by the current function |
| --> $DIR/borrowck-escaping-closure-error-2.rs:21:14 |
| | |
| LL | Box::new(|| books.push(4)) |
| | ^^ ----- `books` is borrowed here |
| | | |
| | may outlive borrowed value `books` |
| help: to force the closure to take ownership of `books` (and any other referenced variables), use the `move` keyword |
| | |
| LL | Box::new(move || books.push(4)) |
| | ^^^^^^^ |
| |
| error: aborting due to previous error |
| |
| For more information about this error, try `rustc --explain E0373`. |
