Debuggability

All public types implement Debug (C-DEBUG)

If there are exceptions, they are rare.

Debug representation is never empty (C-DEBUG-NONEMPTY)

Even for conceptually empty values, the Debug representation should never be empty.

#![allow(unused)]
fn main() {
let empty_str = "";
assert_eq!(format!("{:?}", empty_str), "\"\"");

let empty_vec = Vec::<bool>::new();
assert_eq!(format!("{:?}", empty_vec), "[]");
}