fn vec_sub(l: [f32; 3], r: [f32; 3]) -> [f32; 3] {
    return [l[0]-r[0], l[1]-r[1], l[2]-r[2]];
}

fn foo(x: f32) {
    let a = [x, x, 0.0];
    let b = [x, x, x]; // works
    // let b = [x * 0.5, x * 0.5, x]; // does not work
    vec_sub(a, b);
}

fn main() {}