Function ostree_sys::ostree_repo_traverse_reachable_refs

pub unsafe extern "C" fn ostree_repo_traverse_reachable_refs(
    self_: *mut OstreeRepo, 
    depth: c_uint, 
    reachable: *mut GHashTable, 
    cancellable: *mut GCancellable, 
    error: *mut *mut GError
) -> gboolean

This is supported on crate feature v2018_6 only.