borrow-lifetimes-single.rs

#[derive(Debug)]
struct I;

struct J {
    things: Vec<I>,
}

impl J {
    pub fn new() -> Self {
        J { things: Vec::new() }
    }

    pub fn add_to_things(&mut self, thing: I) -> &I {
        let idx = self.things.len();

        self.things.push(thing);

        &self.things[idx]
    }

    pub fn get_thing(&self) -> &I {
        return &self.things[0];
    }
}

fn main() {
    let mut s = J::new();

    let thing_inserted = s.add_to_things(I {}); // lifetime of this borrow extended to line 32?
    let thing_back = s.get_thing(); // does not compile

    println!("{:#?}", thing_inserted);
}