+
+ AC_REQUIRE([gl_FEATURES_H])
+
+ dnl Check for declarations of anything we want to poison if the
+ dnl corresponding gnulib module is not in use.
+ gl_WARN_ON_USE_PREPARE([[
+/* On some systems, this header is not self-consistent. */
+#if !(defined __GLIBC__ || defined __UCLIBC__)
+# include <sys/socket.h>
+#endif
+#ifdef __TANDEM
+# include <netdb.h>
+#endif
+#include <arpa/inet.h>
+ ]], [inet_ntop inet_pton])