+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#if (SIZEOF_LONG != 4 && SIZEOF_LONG != 8)
+ error This function works only on systems for which sizeof(long) is 4 or 8.
+/* The previous line would begin with `#error,' but some compilers can't
+ handle that even when the condition is false. */
+#endif
+