cargo::core::compiler::fingerprint

Function find_stale_file

Source 
fn find_stale_file<I, P>(
    mtime_cache: &mut HashMap<PathBuf, FileTime>,
    checksum_cache: &mut HashMap<PathBuf, Checksum>,
    reference: &Path,
    paths: I,
    use_checksums: bool,
) -> Option<StaleItem>
where
    I: IntoIterator<Item = (P, Option<(u64, Checksum)>)>,
    P: AsRef<Path>,
Expand description

The reference file is considered as “stale” if any file from paths has a newer mtime.