Re: Suggestion: error "tag ... already exists" should distinguish between tagging different or same commit:

From: Hilco Wijbenga <hilco.wijbenga@gmail.com>
Date: Jun 9, 2025, 19:37 UTC
Message-ID: <CAE1pOi34+btHyV8GbjpFPcJ+2ixu59ce4eAE=Q7F4JEcuJyXnw@mail.gmail.com>
In-Reply-To: <xmqqcybcrc2u.fsf@gitster.g>

Does it really make sense for that first example to fail, though? "git tag hello v1.9.5" is an idempotent operation, isn't it? The second attempt is a no-op?

If "git tag ..." simply does nothing if the tag already exists (as requested) then that would make the OP's issue go away: only the 2nd example would fail.

On Mon, Jun 9, 2025 at 11:45 AM Junio C Hamano <gitster@pobox.com> wrote:

Show 40 quoted lines

>
> M Hickford <mirth.hickford@gmail.com> writes:
>
> > Hi. Presently, the error "tag ... already exists" doesn't distinguish
> > between tagging the same commit or a different commit:
> >
> >      >git tag hello v1.9.5
> >
> >      >git tag hello v1.9.5
> >      fatal: tag 'hello' already exists
> >
> >      >git tag hello v2.0.0
> >      fatal: tag 'hello' already exists
> >
> > To inform the user, it would be nice to distinguish these cases, perhaps:
> >
> >      >git tag hello v1.9.5
> >      fatal: tag 'hello' already exists pointing at
> > d4e6038a068d0aecd5ec28c83afbfc6d4903092f
> >
> >      >git tag hello v2.0.0
> >      fatal: tag 'hello' already exists but points at
> > 18a07354e33f86c8349ffdc300d9087876658264
> >
> > The second error is typically more concerning than the first.
> >
> > What do you think?
>
> Not interested.  When the user gets that "fatal" message, the
> existing tag did not get modified, so they can just do whatever
> check they want (like "git range-diff v1.9.5...hello") themselves.
>
> Besides, in the above examples, is d4e6038a something the user
> immediately recognises as the same as v1.9.5 or the object existing
> v1.9.5 tag points at?  I somehow doubt it.  So after getting the
> error, there needs some digging to figure out how v1.9.5 and
> existing hello are related to each other _anyway_, I would think.
>
>
>