+void fail(const char *emsg);
+
+void libdie(const char *lib, int l, const char *str);
+#define XA(w) ((w) ? (void)0 : libdie("X", __LINE__, #w))
+
+void gsldie(int l, const char *what, int status);
+#define GA(w) ({int _ga_r= (w); if (w) gsldie(__LINE__,#w,_ga_r);})