Code shared from the Rust Playground

playground.rs

#![warn(clippy::pedantic, clippy::nursery)]
#![forbid(unsafe_code)]

use num_integer::Integer; // 0.1

#[derive(Copy, Clone, Eq, PartialEq, Debug)]
enum S {
    F,
    B,
    FB,
}

fn fb<T: Integer>(n: &T) -> Option<S> {
    let n3 = T::one() + T::one() + T::one();
    let n5 = T::one() + T::one() + T::one() + T::one() + T::one();
    let m3 = n.is_multiple_of(&n3);
    let m5 = n.is_multiple_of(&n5);
    if m3 && m5 {
        return Some(S::FB);
    }
    if m3 {
        return Some(S::F);
    }
    if m5 {
        return Some(S::B);
    }
    None
}

#[must_use]
const fn fbu(n: usize) -> Option<S> {
    if n % 15 == 0 {
        return Some(S::FB);
    }
    if n % 3 == 0 {
        return Some(S::F);
    }
    if n % 5 == 0 {
        return Some(S::B);
    }
    None
}

fn main() {
    for i in 0..u8::MAX {
        match fb(&i) {
            Some(s) => println!(
                "{}zz",
                match s {
                    S::F => "Fi",
                    S::B => "Bu",
                    S::FB => "FizzBu",
                }
            ),
            _ => println!("{i}"),
        }
    }
}