-const char* mount_result_to_string(MountResult i);
-MountResult mount_result_from_string(const char *s);
+const char* mount_result_to_string(MountResult i) _const_;
+MountResult mount_result_from_string(const char *s) _pure_;
+
+void warn_if_dir_nonempty(const char *unit, const char* where);