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
|
-21 | Box::new(|| books.push(4))
+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
|
-21 | Box::new(move || books.push(4))
+LL | Box::new(move || books.push(4))
| ^^^^^^^
error: aborting due to previous error
+For more information about this error, try `rustc --explain E0373`.