Function resolve_existing 

pub fn resolve_existing(
    root: &Path,
    relative: &Path,
) -> Result<PathBuf, ResolveError>

Resolve an existing reviewed relative path while confining symbolic links.

The result is host-normalized, absolute, and below the canonical root. Relative inputs may contain only ordinary or current-directory components.

Errors

Returns an error when the input is invalid, canonicalization fails, or symbolic-link resolution escapes the root.