Generify with compiler errors - Adding starting with zero

main.rs

fn sum<T>(numbers: &[T]) -> T
where
    T: Add<Output = T> + Copy + Zero,
{
    let mut total: T = T::zero();
    for i in numbers.into_iter() {
        total = total + *i;
    }
    total
}

fn main() {
    let ints = vec![23, -4, 3, 10];
    let floats = vec![23.0, -4.0, 3.0, 10.0];

    assert_eq!(sum(&ints), 32);
    assert_eq!(sum(&floats), 32.0);
}