Re: Regarding Git and Branch Naming

From: Philip Oakley <philipoakley@iee.email>
To: Jeff King <peff@peff.net>, Chris Torek <chris.torek@gmail.com>
Cc: Craig H Maynard <chmaynard@me.com>, git@vger.kernel.org
Subject: Re: Regarding Git and Branch Naming
Date: Fri, 26 Jun 2020 22:33:14 +0100	[thread overview]
Message-ID: <6b9d76e4-68dd-8e57-f96a-318579dea6f3@iee.email> (raw)
In-Reply-To: <20200626203539.GA1173768@coredump.intra.peff.net>

On 26/06/2020 21:35, Jeff King wrote:
> On Fri, Jun 26, 2020 at 11:33:53AM -0700, Chris Torek wrote:
>
>> On Fri, Jun 26, 2020 at 10:19 AM Craig H Maynard <chmaynard@me.com> wrote:
>>> Does the git init command really need to create a default branch? Perhaps that step could be left to the user.
>> The HEAD pseudo-ref must exist and must contain a valid OID or
>> branch name.  (If it does not exist, Git says that the directory
>> is not a repository.  Perhaps this test could be weakened, but
>> that's definitely a fairly big change.)
>>
>> In a new, empty repository there are no valid OIDs, so HEAD must
>> contain a branch name.  The branch itself need not exist, but
>> whatever name is in HEAD is the branch that will be created
>> when the user makes the first commit.
> We definitely _could_ extend HEAD to allow a "not pointing at anything"
> state. Presumably for reading that would behave like the "pointing at a
> branch that doesn't exist yet" case. But I think the experience it
> creates for writing is not very good. I.e., I think the best we could do
> is something like:
>
>   $ git init
>   $ git add some-files
>   $ git commit -m whatever
>   fatal: HEAD does not point to any branch
>   hint: use "git checkout -b <branch>" to make commits on <branch>
>
> Perhaps that's not _too_ bad, but it feels a bit unfriendly (and
> definitely more likely to cause backwards compatibility issues than
> picking _some_ default name). There would also be a lot of corner cases
> to cover and debug (e.g., "git checkout foo" moving away from the "no
> branch" state should make the usual complaints if we'd have to overwrite
> or modify index and untracked files).
>
>
A wild bikeshed question: Is HEAD itself protected as a branch name e.g.
that HEAD could contain `ref: HEAD` or `ref: refs/heads/HEAD`? (or maybe
the null  oid

It sort of feels that we may already have some sort of protection for
the first self reference - i.e. exists, but not defined (self-reference).

Philip