E0515 - Error codes index
Description: Book listing all Rust error codes

# Error code E0515

A reference to a local variable was returned.

Erroneous code example:

    #![allow(unused)]
    fn main() {
    fn get_dangling_reference() -> &'static i32 {
        let x = 0;
        &x
    }
    }

    #![allow(unused)]
    fn main() {
    use std::slice::Iter;
    fn get_dangling_iterator<'a>() -> Iter<'a, i32> {
        let v = vec![1, 2, 3];
        v.iter()
    }
    }

Local variables, function parameters and temporaries are all dropped before the end of the function body. So a reference to them cannot be returned.

Consider returning an owned value instead:

    #![allow(unused)]
    fn main() {
    use std::vec::IntoIter;

    fn get_integer() -> i32 {
        let x = 0;
        x
    }

    fn get_owned_iterator() -> IntoIter<i32> {
        let v = vec![1, 2, 3];
        v.into_iter()
    }
    }