* When one <tree-ish> is given, the working tree and the named
tree are compared, using `git-diff-index`. The option
- `--cached` can be given to compare the index file and
+ `--index` can be given to compare the index file and
the named tree.
+ `--cached` is a deprecated alias for `--index`. It's use is
+ discouraged.
* When two <tree-ish>s are given, these two trees are compared
using `git-diff-tree`.
+
------------
$ git diff <1>
-$ git diff --cached <2>
+$ git diff --index <2>
$ git diff HEAD <3>
------------
+