#define DIFF_OPT_SILENT_ON_REMOVE (1 << 5)
#define DIFF_OPT_FIND_COPIES_HARDER (1 << 6)
#define DIFF_OPT_FOLLOW_RENAMES (1 << 7)
-/* (1 << 8) unused */
+#define DIFF_OPT_RENAME_EMPTY (1 << 8)
/* (1 << 9) unused */
#define DIFF_OPT_HAS_CHANGES (1 << 10)
#define DIFF_OPT_QUICK (1 << 11)