howto handle name clashes

Hi,

how to handle name clashes for branches and tags? Is there anything I can add to the refspec to make the name unique?

E.g.
- for merging "git merge --no-ff refs/branches/test" works, but
generates a not so nice default merge message. ("merged  commit
refs/branches/test" instead of "merged branch test")
- how to drop a remote tag/branch ("git push origin :test" does not work)

On Fri, Mar 23, 2012 at 02:06:01PM +0100, Sven Strickroth wrote:

You can always use a more fully-qualified name to disambiguate (e.g., "tags/foo", or "refs/tags/foo").

Did you mean "refs/heads/test"?

I would have thought we would full-qualify the refname first, and then use that to determine the message. Doing a simple test, it looks like "git merge foo" gets you "Merge branch 'foo'", but "git merge heads/foo" will get you "Merge branch 'heads/foo'". We should be able to do better in the latter case.

Does "git push origin :heads/foo" (or :tags/foo) not work?

-Peff

Am 23.03.2012 18:12 schrieb Jeff King:

yes. Your example was the correct one. Thanks for spotting my problem.

seems to work. Thanks.

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.

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.

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

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.

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

Am 23.03.2012 18:12 schrieb Jeff King:

well, ":heads/foo" does not work. Imagine I want to drop a remote branch which is ambiguous (e.g. a tag with same name exists) on the repository:

"git push origin :food"

gives me: "error: dst refspec food matches more than one."

However, deleting the remote tag (:tags/foo) works with your suggestion.

"git push origin :refs/remotes/origin/foo" showed success (and warning "remote: warning: Allowing deletion of corrupt ref."), but did not work.

Sven Strickroth <sven.strickroth@tu-clausthal.de> writes:

That's the price you pay for naming different things the same and having to disambiguate it.

"git push origin :refs/tags/test"

It is sad that some people teach new people shorthand without telling them that what they are teaching are merely shorthand and cause confusion like this.