-int bus_gvariant_get_size(const char *signature);
-int bus_gvariant_get_alignment(const char *signature);
-int bus_gvariant_is_fixed_size(const char *signature);
+int bus_gvariant_get_size(const char *signature) _pure_;
+int bus_gvariant_get_alignment(const char *signature) _pure_;
+int bus_gvariant_is_fixed_size(const char *signature) _pure_;