error[E0373]: closure may outlive the current function, but it borrows `books`, which is owned by the current function --> $DIR/borrowck-escaping-closure-error-1.rs:13:11 | LL | spawn(|| books.push(4)); | ^^ ----- `books` is borrowed here | | | may outlive borrowed value `books` | note: function requires argument type to outlive `'static` --> $DIR/borrowck-escaping-closure-error-1.rs:13:5 | LL | spawn(|| books.push(4)); | ^^^^^^^^^^^^^^^^^^^^^^^ help: to force the closure to take ownership of `books` (and any other referenced variables), use the `move` keyword | LL | spawn(move || books.push(4)); | ++++ error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0373`.