Re: Regarding Git and Branch Naming

From: Jeff King <peff@peff.net>
Date: Jun 26, 2020, 20:35 UTC
Message-ID: <20200626203539.GA1173768@coredump.intra.peff.net>
In-Reply-To: <CAPx1GvcZk2o7f8-27xokwxUayWwO+t5qdsMjLrjBymc+WHznmw@mail.gmail.com>

On Fri, Jun 26, 2020 at 11:33:53AM -0700, Chris Torek wrote:

Show 12 quoted lines

> 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).

-Peff