+/* GCC lets us add "attributes" to functions, function
+ parameters, etc. to indicate their properties.
+ See the GCC manual for details. */
+#define UNUSED __attribute__ ((unused))
+#define NO_RETURN __attribute__ ((noreturn))
+#define NO_INLINE __attribute__ ((noinline))
+#define PRINTF_FORMAT(FMT, FIRST) __attribute__ ((format (printf, FMT, FIRST)))
+
+/* Halts the OS, printing the source file name, line number, and
+ function name, plus a user-specific message. */
+#define PANIC(...) debug_panic (__FILE__, __LINE__, __func__, __VA_ARGS__)