Re: Possible bug report: git checkout tag problem

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi Myles,

On Mon, 8 Jan 2018, Myles Fong wrote:

> Brief description:
> When two tags are pointing to the same commit, e.g. tagA and tagB, if I
> do `git checkout tagA` then `git checkout tagB`,  and then `git status`,
> it shows `HEAD detached at tagA`
> 
> Expected behaviour:
> I'm expecting it to show `HEAD detached at tagB`, though I understand
> this makes no difference for the repo code, but still a bit confusing
> for me.

The problem here is that Git understands something different from what you
intended: if you say `git checkout <commit-ish>`, Git is mostly interested
in the revision, i.e. the commit. Only if that parameter refers to a local
branch name (which is the only type of ref Git expects to advance via the
worktree) does it switch to a named branch. Otherwise it switches to what
I like to call "unnamed branch" (and which for historical reasons is
called "detached HEAD" by Git, something that is unlikely to be understood
without explicit explanation).

Now, as a convenience, Git tries to name the revision when it is on such
an unnamed branch. If a tag points to it, it uses the name of that tag to
describe it. If *multiple* tags point to it, it uses the newest one.

That's why you see what you see. It is intended behavior...

Ciao,
Johannes