rustlings/exercises/move_semantics/move_semantics4.rs

// move_semantics4.rs
// Refactor this code so that instead of having `vec0` and creating the vector
// in `fn main`, we instead create it within `fn fill_vec` and transfer the
// freshly created vector from fill_vec to its caller. Scroll for hints!

fn main() {
    let vec0 = Vec::new();

    let mut vec1 = fill_vec(vec0);

    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);

    vec1.push(88);

    println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
}

// `fill_vec()` no longer take `vec: Vec<i32>` as argument
fn fill_vec() -> Vec<i32> {
    let mut vec = vec;

    vec.push(22);
    vec.push(44);
    vec.push(66);

    vec
}












// Stop reading whenever you feel like you have enough direction :) Or try
// doing one step and then fixing the compiler errors that result!
// So the end goal is to:
// - get rid of the first line in main that creates the new vector
// - so then `vec0` doesn't exist, so we can't pass it to `fill_vec`
// - we don't want to pass anything to `fill_vec`, so its signature should
//   reflect that it does not take any arguments
// - since we're not creating a new vec in `main` anymore, we need to create
//   a new vec in `fill_vec`, similarly to the way we did in `main`