+# if defined _NO_UNSUPPORTED || defined _NO_OLDNAMES
+ /* ...including that for the standard POSIX macro, when unsupported
+ * features, or Microsoft's old names, are explicitly forbidden...
+ */
+# pragma GCC poison S_ISBLK
+
+# else /* !(_NO_UNSUPPORTED || _NO_OLDNAMES) */
+ /* ...otherwise assume that the kludge is automatically enabled with
+ * respect to S_ISBLK, (because GCC gratuitously misuses it).
+ */
+# define S_IFBLK 0x3001 /* Block: unsupported on Win32 */
+
+# endif /* !(_NO_UNSUPPORTED || _NO_OLDNAMES) */