Borrowed Data Escapes Outside of Closure

What does this mean?

When you borrow data, you are creating a temporary reference to that data. This reference is only valid for the lifetime of the borrow. If you try to access the data after the borrow has ended, you will get a compiler error.

In the case of closures, the borrow is only valid for the lifetime of the closure. If you try to access the borrowed data outside of the closure, you will get a compiler error.

Example

```rust // This code will not compile fn main() { let x = 10; // Create a closure that borrows x let f = || { println!("{}", x); }; // Try to access x outside of the closure println!("{}", x); } ``` In this example, we create a closure that borrows the variable `x`. We then try to access `x` outside of the closure. This will result in a compiler error because the borrow is no longer valid.

How to fix it

There are two ways to fix this error: 1. **Move the borrowed data into the closure.** This means that the closure will take ownership of the data and will be responsible for deallocating it. 2. **Extend the lifetime of the borrow.** This can be done by using a `'static` lifetime or by using a reference-counted type. In the example above, we can fix the error by moving the borrowed data into the closure: ```rust fn main() { let x = 10; // Create a closure that takes ownership of x let f = move || { println!("{}", x); }; // The closure can now access x because it owns it f(); } ```