+
+ 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([[
+/* Some systems require additional headers. */
+#ifndef __GLIBC__
+# include <stddef.h>
+# include <stdio.h>
+# include <time.h>
+#endif
+#include <wchar.h>
+ ]], [btowc wctob mbsinit mbrtowc mbrlen mbsrtowcs mbsnrtowcs wcrtomb
+ wcsrtombs wcsnrtombs wcwidth])