Remove warning #comparison_chain

Summary

Tested using the following code on 1.71 nightly, performance is exactly the same now.

running 2 tests
test bench_f1 ... bench:         684 ns/iter (+/- 30)
test bench_f2 ... bench:         680 ns/iter (+/- 12)

Reproducer

I tried this code:

#![feature(test)]
extern crate test;

use std::cmp::Ordering;
use std::hint::black_box;
use std::fs::File;
use std::io::{Read, Write, Result};
use std::path::Path;

use test::Bencher;

fn f1(x: u8, y: u8) -> u8 {
    if x > y {
        a()
    } else if x < y {
        b()
    } else {
        c()
    }
}

fn f2(x: u8, y: u8) -> u8 {
    match x.cmp(&y) {
        Ordering::Greater => a(),
        Ordering::Less => b(),
        Ordering::Equal => c(),
    }
}

fn a() -> u8 {
    let mut file = File::create("/dev/null").unwrap();
    let output = black_box(1);
    file.write_all(&[output]).unwrap();
    output
}

fn b() -> u8 {
    let mut file = File::create("/dev/null").unwrap();
    let output = black_box(2);
    file.write_all(&[output]).unwrap();
    output
}

fn c() -> u8 {
    let mut file = File::create("/dev/null").unwrap();
    let output = black_box(3);
    file.write_all(&[output]).unwrap();
    output
}

#[bench]
fn bench_f1(b: &mut Bencher) {
    let mut input = [0u8; 2];
    File::open("/dev/urandom")
        .unwrap()
        .read_exact(&mut input)
        .unwrap();
    let x = black_box(input[0]);
    let y = black_box(input[1]);
    b.iter(|| f1(x, y));
}

#[bench]
fn bench_f2(b: &mut Bencher) {
    let mut input = [0u8; 2];
    File::open("/dev/urandom")
        .unwrap()
        .read_exact(&mut input)
        .unwrap();
    let x = black_box(input[0]);
    let y = black_box(input[1]);
    b.iter(|| f2(x, y));
}

Version

1.71 nightly on x86_64 WSL2

Additional Labels

No response

Start by locating the comparison_chain warning implementation and reproduce the issue with the supplied f1 and f2 benchmark code on Rust 1.71 nightly. Compare the lint's behavior with the benchmark results; done when the warning is removed or its outdated performance guidance is no longer emitted, with the relevant tests updated.