E0505 - Error codes index
Description: Book listing all Rust error codes

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# Error code E0505

A value was moved out while it was still borrowed.

Erroneous code example:

    struct Value {}

    fn borrow(val: &Value) {}

    fn eat(val: Value) {}

    fn main() {
        let x = Value{};
        let _ref_to_val: &Value = &x;
        eat(x);
        borrow(_ref_to_val);
    }

Here, the function `eat` takes ownership of `x`. However, `x` cannot be moved because the borrow to `_ref_to_val` needs to last till the function `borrow`. To fix that you can do a few different things:

- Try to avoid moving the variable.
- Release borrow before move.
- Implement the `Copy` trait on the type.

Examples:

    struct Value {}

    fn borrow(val: &Value) {}

    fn eat(val: &Value) {}

    fn main() {
        let x = Value{};

        let ref_to_val: &Value = &x;
        eat(&x); // pass by reference, if it's possible
        borrow(ref_to_val);
    }

Or:

    struct Value {}

    fn borrow(val: &Value) {}

    fn eat(val: Value) {}

    fn main() {
        let x = Value{};

        let ref_to_val: &Value = &x;
        borrow(ref_to_val);
        // ref_to_val is no longer used.
        eat(x);
    }

Or:

    #[derive(Clone, Copy)] // implement Copy trait
    struct Value {}

    fn borrow(val: &Value) {}

    fn eat(val: Value) {}

    fn main() {
        let x = Value{};
        let ref_to_val: &Value = &x;
        eat(x); // it will be copied here.
        borrow(ref_to_val);
    }

For more information on Rust’s ownership system, take a look at the References & Borrowing section of the Book.