while let on reverse iterator

What it does

Checks for while let expressions on reverse iterators.

Advantage

Readability. Even the reverse loop is shorter and conveys the intent better.

Drawbacks

No response

Example

use std::str::Chars;

fn do_print(mut chars: Chars) {
    while let Some(c) = chars.next_back() {
        print!("{c}");
    }
}

fn main() {
    let s = String::from("\n!dlrow olleH");
    do_print(s.chars());
}

Could be written as:

use std::str::Chars;

fn do_print(mut chars: Chars) {
    for c in chars.by_ref().rev() {
        print!("{c}");
    }
}

fn main() {
    let s = String::from("\n!dlrow olleH");
    do_print(s.chars());
}

Comparison with existing lints

Very much like clippy::while_let_on_iterator this cleans up code.

Additional Context

No response

Start by reading the existing clippy::while_let_on_iterator lint, which this proposal closely compares against. Determine how the reverse-iterator pattern should be recognized and what equivalent for-loop transformation the examples require. Done means the new lint is implemented with appropriate coverage for the shown pattern.