Question about unpack-trees.c and tree_entry_list

The definition of tree_entry_list ist the following

struct tree_entry_list {
	struct tree_entry_list *next;
	unsigned directory : 1;
	unsigned executable : 1;
	unsigned symlink : 1;
	unsigned int mode;
	const char *name;
	const unsigned char *sha1;
};

but it appears to me that the only of the bit fields that is used at all is "directory" : all other uses revert to "mode" which directory presumably could do as well.

Is there something I am overlooking?