Code shared from the Rust Playground

playground.rs

use std::rc::Rc;

#[derive(Debug)]
struct Foo {
    bar: usize,
}

impl Foo {
    fn rc(bar: usize) -> Rc<Self> {
        Rc::new(Foo { bar })
    }
}

fn main(){
    let mut a = vec![Foo::rc(1), Foo::rc(2), Foo::rc(3)];
    let b = vec![Foo::rc(4), Foo::rc(5)];
    
    println!("Before:");
    println!("{:?}", a);
    println!("{:?}\n", b);
    
    a.append(&mut b.clone());
    
    println!("After:");
    println!("{:?}", a);
    println!("{:?}\n", b);
    
    println!("Strong references to b[0] / a[3]: {}", Rc::strong_count(&b[0]))
}