Code shared from the Rust Playground

playground.rs

use std::ops::Sub;

#[derive(Debug, Clone)]
struct Vector<T, const N: usize>([T; N]);

impl<'a, 'b, T, const N: usize> Sub<&'a Vector<T, N>> for &'b Vector<T, N>
where
    &'b T: Sub<&'a T, Output = T>,
{
    type Output = Vector<T, N>;

    fn sub(self: &'b Vector<T, N>, other: &'a Vector<T, N>) -> Self::Output {
        unimplemented!()
    }
}

fn test<T, const N: usize>(p: &Vector<T, N>) -> Vector<T, N>
where
    for<'a> &'a T: Sub<&'a T, Output = T>,
{
    p - p
}

fn main() {
    let a: Vector<i32, 2> = Vector([1, 1]);
    let b = Vector([2, 2]);
    println!("Output: {:?}", &a - &b); // This works
    println!("Output: {:?}", test(&a)); // This fails
}