Function absolute_with 

pub fn absolute_with<P, Q>(path: P, relative_to: Q) -> Result<PathBuf>
where
    P: AsRef<Path>,
    Q: AsRef<Path>,

Returns the path in its absolute form without resolving symlinks.

On Unix systems, .. components are a kind of link so these aren’t resolved. On Windows .. components are resoloved.

Fails under the same conditions as std::path::absolute. In practice this is only likely to fail if both paths are empty.