sys/cdefs.h makes _XOPEN_SOURCE cause _POSIX_C_SOURCE to be overriden.
@@ -49,7 +49,7 @@ enum
#define PROGRAM_NAME "xC"
// fmemopen
#define _POSIX_C_SOURCE 200809L
#define _XOPEN_SOURCE 700
#include "common.c"
#include "xD-replies.c"
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