If you read the discussion on std's new dbg! macro, you'll find that there are good reasons why it shouldn't affect release builds. As a silent protest against the decision, I made my own version.

use sensible_dbg::dbg;

fn factorial(n: u32) -> u32 {
    if dbg!(n <= 1) {
        dbg!(1)
    } else {
        dbg!(n * factorial(n - 1))
    }
}