Function nar_hash_source_tree 

pub fn nar_hash_source_tree(
    dir: &Path,
    name: &str,
) -> Result<SourceHash, NarError>

NAR-serialize dir, hash it, and compute the CppNix source store path + SRI narHash.

The name argument is the final -<name> segment of the resulting store path. For flake path: refs CppNix uses "source" unconditionally.

Errors

Returns a NarError if the path can’t be serialized (e.g. broken symlink, unreadable directory).