Function dashboard_source_stamp

build.rs:160–189

Content hash of the production dashboard source inputs (each input's path + bytes), independent of filesystem mtimes. Returns `None` when there are no source inputs - e.g. a published crate that ships only the prebuilt dist - so a stamp is never recorded and a rebuild is never triggered for crates.io.

(source_inputs: &[PathBuf])

/// source inputs - e.g. a published crate that ships only the prebuilt dist -
/// so a stamp is never recorded and a rebuild is never triggered for crates.io.
fn dashboard_source_stamp(source_inputs: &[PathBuf]) -> Option<String> {
    if source_inputs.is_empty() {
        return None;
    }
    // Hash in a stable path order so the stamp depends only on file content,
    // not on the unspecified `read_dir` traversal order. Sort by the same
    // normalized forward-slash string key the JS builder uses
    // (build.shared.mjs `normalizedSourcePath`) so the two stamps stay
    // byte-identical; `PathBuf`'s default component-wise ordering can diverge
    // from JS string ordering.
    let mut paths: Vec<&PathBuf> = source_inputs.iter().collect();
    paths.sort_by(|a, b| {
        normalized_dashboard_source_path(a).cmp(&normalized_dashboard_source_path(b))
    });
    let mut hasher = FNV_OFFSET_BASIS;
    for path in paths {
        // Hashing the path makes adds/removes/renames flip the stamp even when
        // the surviving files are byte-identical.
        fnv_hash_bytes(
            &mut hasher,
            normalized_dashboard_source_path(path).as_bytes(),
        );
        fnv_hash_bytes(&mut hasher, &[0]);
        if let Ok(bytes) = fs::read(path) {
            fnv_hash_bytes(&mut hasher, &bytes);
        }
        fnv_hash_bytes(&mut hasher, &[0]);
    }
    Some(format!("{hasher:016x}"))
}

/// True when the dashboard source inputs differ from the content stamp recorded
/// by the previous build in this `OUT_DIR` - i.e. the sources genuinely changed