Function cmp_ascii_case_insensitive 

pub fn cmp_ascii_case_insensitive(a: &str, b: &str) -> Ordering

Byte-by-byte ASCII case-insensitive ordering, zero-allocation.

Compares two strings by mapping each byte through to_ascii_lowercase() using iterator adapters. For ASCII-only content (resource names, filenames) this is equivalent to a.to_ascii_lowercase().cmp(&b.to_ascii_lowercase()) without the per-call String allocation.