Function check 

pub fn check(
    layout: &Layout,
    path: &Path,
    projects: &[String],
) -> Result<Freshness>

Compare the stamp inside path against the corpus it claims to mirror.

With no explicit projects, the stamp’s own project list is used: the file records what it covered, so a caller need not repeat it.

Errors

Returns an error if path cannot be read, or the corpus cannot be digested.