Re: Unify annotated and non-annotated tags

From: Igor Djordjevic <igor.d.djordjevic@gmail.com>
Date: Nov 11, 2017, 01:46 UTC
Message-ID: <ec4be1c2-a0cc-cec8-a566-06c11c8abe06@gmail.com>
In-Reply-To: <CAPkN8x+MELCnttE+xptKzYXsYPWqbiE59LABrwNBhFroayc+wQ@mail.gmail.com>

Hi Anatoly,

On 10/11/2017 11:58, anatoly techtonik wrote:

Show 8 quoted lines

> It is hard to work with Git tags, because on low level hash
> of non-annotated tag is pointing to commit, but hash for
> annotated tag is pointing to tag metadata.
> 
> On low level that means that there is no way to get commit
> hash from tag in a single step. If tag is annotated, you need
> to find and parse ^{} string of show-ref, if not, then look for
> string without ^{}.

That is not quite true, as you can always dereference any tag (annotated or not) using "<tag>^0" notation, see git-rev-parse[1]:

  "As a special rule, <rev>^0 means the commit itself and is used when 
  <rev> is the object name of a tag object that refers to a commit 
  object."

Show 12 quoted lines

> So, why not just make all tags work the same so that every
> tag has its own hash and you need to dereference it in the
> same way to get commit hash?
> 
> This way I could get all commit hashes with just:
> 
>     git show-ref --tags -d | grep "\^{}"
> 
> or abandon ^{} completely and show commit hashes on -d:
> 
>     git show-ref --tags --dereference
>

Depending on what you would _exactly_ like to do, you could get all tagged commit hashes like this:

	git rev-list --tags --no-walk

Note that each commit will be listed only once, even if more tags (annotated or not) point to it.

If you would like to mimic output of "git show-ref", repeating commits for each tag pointing to it and showing full tag name as well, you could do something like this, for example:

	for tag in $(git for-each-ref --format="%(refname)" refs/tags)
	do
		printf '%s %s\n' "$(git rev-parse $tag^0)" "$tag"
	done

Hope that helps a bit.

Regards, Buga

[1] https://git-scm.com/docs/git-rev-parse#git-rev-parse-emltrevgtemegemHEADv1510em