struct Foo<'a> {
    bar: &'a str,
}

impl<'a> Into<String> for Foo<'a> {
    fn into(self) -> String {
        String::from(self.bar)
    }
}

fn main() {
    let f: Foo = Foo { bar: "bar" };
    assert_eq!("bar", f.into());
}