Function resolve 

fn resolve(root: &Path, path: &str) -> Landed

Where path lands under root. A missing file has no canonical path, so its PARENT is canonicalized instead - what keeps the prefix check honest for a path whose directory is a symlink out. A path that canonicalizes neither way and needs no rewriting is Walked as the spelled path itself; one the collapse rewrites is Collapsed, so a .. climbing past the root is still an escape when the chain it climbs through is not on disk, and a spell that collapses onto a symlink out is never read through the rewrite.