See discussion at:
https://bugzilla.gnome.org/show_bug.cgi?id=610183
#endif
#if __GNUC__ >= 3
-#define HB_GNUC_UNUSED __attribute__((unused))
#define HB_GNUC_PURE __attribute__((pure))
#define HB_GNUC_CONST __attribute__((const))
#else
-#define HB_GNUC_UNUSED
#define HB_GNUC_PURE
#define HB_GNUC_CONST
#endif
+#if __GNUC__ >= 4
+#define HB_GNUC_UNUSED __attribute__((unused))
+#else
+#define HB_GNUC_UNUSED
+#endif
#if (defined(__WIN32__) && !defined(__WINE__)) || defined(_MSC_VER)