+#if GNULIB_defined_O_NONBLOCK
+ /* The only known platform that lacks O_NONBLOCK is mingw, but it
+ also lacks named pipes and Unix sockets, which are the only two
+ file types that require non-blocking handling in open().
+ Therefore, it is safe to ignore O_NONBLOCK here. It is handy
+ that mingw also lacks openat(), so that is also covered here. */
+ flags &= ~O_NONBLOCK;
+#endif
+