Re: Can't diff against the 00000000 revision

From: Stefan Monnier <monnier@iro.umontreal.ca>
Date: Jan 12, 2016, 16:26 UTC
Message-ID: <jwvr3hmwz1n.fsf-monnier+gmane.comp.version-control.git@gnu.org>
In-Reply-To: <20160112153239.GA8041@sigill.intra.peff.net>

Show 5 quoted lines

>> I currently work around the problem by adding a dummy empty branch, but
>> being able to use the revision 00000000 as a known reference to an empty
>> tree would come in really handy, and since it's already used at various
>> places in Git (post-receive hook and "git show" output, at least), it
>> would seem like a natural extension.

> The empty tree also has a name:
>
>   $ git hash-object -t tree /dev/null
>   4b825dc642cb6eb9a060e54bf8d69288fbee4904

Yay!

   git diff 4b825dc642cb6eb9a060e54bf8d69288fbee4904..d59cfff346c3e210adc26501f8cebf8da5ab2e7d

seems to give me the expected diff. Thanks!

> And hopefully that explains why "000000" does not necessarily make a
> good placeholder for "the empty thing". There are multiple empty things,
> and it is not clear what:

>   git diff 0000000 1234abcd

> means. Is 0000000 a tree? A blob?

Well, Git is the one who uses 000000 to refer to an empty thing, but indeed it seems like it does inconsistently: it's sometimes used as the "empty blob" and sometimes as an "empty tree".

        Stefan