+#if defined(__sun__)
+ /*
+ * On Solaris, when _XOPEN_EXTENDED is set, its header file
+ * forces the programs to be XPG4v2, defeating any _XOPEN_SOURCE
+ * setting to say we are XPG5 or XPG6. Also on Solaris,
+ * XPG6 programs must be compiled with a c99 compiler, while
+ * non XPG6 programs must be compiled with a pre-c99 compiler.
+ */
+# if __STDC_VERSION__ - 0 >= 199901L
+# define _XOPEN_SOURCE 600
+# else
+# define _XOPEN_SOURCE 500
+# endif
+#elif !defined(__APPLE__) && !defined(__FreeBSD__) && !defined(__USLC__) && !defined(_M_UNIX) && !defined(sgi)