Re: [PATCH v2] diff: support --cached on unborn branches

From: Junio C Hamano <gitster@pobox.com>
Date: Oct 31, 2010, 03:12 UTC
Message-ID: <7vwroz3vj8.fsf@alter.siamese.dyndns.org>
In-Reply-To: <1288437377-30405-1-git-send-email-pclouds@gmail.com>

Nguyễn Thái Ngọc Duy  <pclouds@gmail.com> writes:

Show 12 quoted lines

> "git diff --cached" (without revision) used to mean "git diff --cached
> HEAD" (i.e. the user was too lazy to type HEAD). This "correctly"
> failed when there was no commit yet. But was that correctness useful?
>
> This patch changes the definition of what particular command means.
> It is a request to show what _would_ be committed without further "git
> add". The internal implementation is still the same "git diff
> --cached HEAD" when HEAD exists, but when there is no commit yet, it
> compares the index with an empty tree object to achieve the desired
> result.
>
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>

Will take a look at it, and queue.  Thanks.

>  "git diff --cached HEAD" does fail, but I don't really care.

I _do_ care, and so should you. And I think it _should_ fail, if the user explicitly asked to compare the index with HEAD that does not exist yet.

As we are updating the semantics of a Porcelain command, there should be an update that explains the new usage in the documentation, no?