Re: [PATCH v2.5 2/2] tag: prevent nested tags

From: Jeff King <peff@peff.net>
Date: Apr 4, 2019, 12:27 UTC
Message-ID: <20190404122722.GA23024@sigill.intra.peff.net>
In-Reply-To: <xmqqftqyf76a.fsf@gitster-ct.c.googlers.com>

On Thu, Apr 04, 2019 at 06:31:25PM +0900, Junio C Hamano wrote:

Show 12 quoted lines

> Jeff King <peff@peff.net> writes:
> 
> > I do still think it is likely to be a mistake. I think Junio's point,
> > though is: who cares if the mistake was made? For the most part you can
> > continue to use the tag as if the mistake had never been made, because
> > Git peels through multiple layers as necessary.
> 
> Nicely said.
> 
> If we forget to peel, that is a bigger problem, but I do not think
> it makes any sense to single out tag-of-tag as "curious" and forbid
> it, when we silently allow tag-of-blob or tag-of-tree happily.

IMHO the difference between those cases is that it is very easy to type something natural to get a tag of tag, like:

  git tag -m foo mytag
  # oops, try again
  git tag -m bar -f mytag mytag

but you have to take pretty specific steps to get a tag of a blob or tree, like:

  git tag mytag HEAD:path

or

  git tag mytag HEAD^{tree}

Unless you have a ref pointing to a blob or tree in the first place, of course. But then it is a chicken-and-egg question. Didn't you have to do something specific to get that tag in the first place?

-Peff