Function measure_rust 

pub fn measure_rust(
    root: &Path,
    base: &str,
    thresholds: RustThresholds,
    ignore: &[String],
    exempt_lines: &BTreeMap<String, BTreeSet<u32>>,
    features: &[String],
) -> Result<Outcome>

Diff-scoped Rust coverage floor: the cargo llvm-cov regions/lines metrics measured over the <base>...HEAD changed .rs lines instead of the whole tree. ignore is the coverage-rule exemptions; an exempt file’s lines drop out of the ratios with it.