fn eval(
        &self,
        link: PackageLink<'_>,
        mut pred_fn: impl FnMut(DependencyReq<'_>) -> bool,
    ) -> bool {
        pred_fn(link.normal())
            || self.include_dev && pred_fn(link.dev())
            || self.include_build && pred_fn(link.build())
    }
Select normal, dev, or build dependencies as requested (--include-build, --include-dev), and
apply `pred_fn` to whatever's selected.
cargo-guppy/src/core.rs