Re: Should `@` be really a valid git tag name?

On Fri, Sep 17, 2021 at 01:53:52PM -0700, Junio C Hamano wrote:

Carlo Arenas [off-list ref] writes:

quoted

On Fri, Sep 17, 2021 at 7:12 AM [off-list ref] wrote:

quoted

A SO commenter pointed out, that git-check-ref-format forbids @ and
maybe I should report this as a potential bug. Is it?

a reference that is named "@" only is invalid, but refs/tags/@ is not.

;-)  

"git check-ref-format master ; echo $?" would show that any single
level name is "forbidden", so probably the SO commenter (whatever
that is) was confused---it is not about @ at all.

In any case, a tag whose name is @ may be another source of
confusion in the modern world, after we added @ as a synonym to
HEAD.  I do not know, for example, offhand which between the HEAD or
that tag "git show @" would choose.  It makes sense to avoid it.

In the past when we've had confusing names (like refs/heads/HEAD), we
continue to allow them at the plumbing level (to retain backwards
compatibility), but flag them at the porcelain level to prevent users
shooting themselves in the foot. This seems like a good candidate for
that (for both git-branch and git-tag).

-Peff