Re: howto handle name clashes

From: Jeff King <peff@peff.net>
Date: Mar 23, 2012, 18:29 UTC
Message-ID: <20120323182941.GA14236@sigill.intra.peff.net>
In-Reply-To: <4F6CB649.8080006@tu-clausthal.de>

On Fri, Mar 23, 2012 at 06:43:37PM +0100, Sven Strickroth wrote:

> Really problematic is checkout:
> "git checkout heads/foo" creates a detached HEAD (is this intended).
> However, "git checkout heads/foo -B foo" can be used.

Checkout is unlike regular ref lookup in that it prefers branches to other forms (because it is fundamentally a branch operation). So "git checkout foo" should always choose "refs/heads/foo". We do still seem to give the ambiguity warning, though, which seems like overkill.

I think that generally people would want to get rid of ambiguous refs as soon as they notice them, as they are a recipe for disaster. So the warning being annoying has not been considered a huge problem.

> Is there a git command to find out if a name is ambiguous?
> "git rev-parse foo" outputs "warning: refname 'test' is ambiguous.", but
> the return code is zero.

I think you could do:

  case "$(git show-ref --tags --heads $name | wc -l)" in
  0) echo "$name does not exist" ;;
  1) echo "$name is unambiguous" ;;
  *) echo "$name is ambiguous" ;;
  esac

You could also get a list of all ambiguous refs like this:

  git for-each-ref --format='%(refname:short)' refs/heads refs/tags |
  egrep '^(heads|tags)'

The ":short" modifier will shorten names unambiguously, so it ends up leaving the "heads" and "tags" in for ambiguous names.

-Peff