From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 06 Feb 2012 05:30:15 GMT
Subject: Re: Bug: "git checkout -b" should be allowed in empty repo
Message-ID: <7vk440a5qw.fsf@alter.siamese.dyndns.org>
In-Reply-To: <20120206051834.GA5062@sigill.intra.peff.net>

Jeff King <peff@peff.net> writes:

> Sure, that's one way to do it. But I don't see any point in not allowing
> "git checkout -b" to be another way of doing it. Is there some other use
> case for "git checkout -b" from an unborn branch? Or is there some
> harmful outcome that can come from doing so that we need to be
> protecting against? Am I missing something?

Mostly because it is wrong at the conceptual level to do so.

	git checkout -b foo

is a short-hand for

	git checkout -b foo HEAD

which is a short-hand for

	git branch foo HEAD &&
        git checkout foo

But the last one has no chance of working if you think about it, because
"git branch foo $start" is a way to start a branch at $start and you need
to have something to point at with refs/heads/foo.

So we are breaking the equivalence between these three only when HEAD
points at an unborn branch.