From: Marc Branchaud <marcnarc@xiplink.com>
To: Nicolas Pitre <nico@fluxnic.net>
Cc: "Michael Haggerty" <mhagger@alum.mit.edu>,
"Johan Herland" <johan@herland.net>, "Jeff King" <peff@peff.net>,
"Junio C Hamano" <gitster@pobox.com>,
"Git mailing list" <git@vger.kernel.org>,
"Carlos Martín Nieto" <cmn@elego.de>,
"Michael Schubert" <mschub@elegosoft.com>
Subject: Re: Local tag killer
Date: Mon, 30 Sep 2013 17:14:48 -0400 [thread overview]
Message-ID: <5249E9C8.1070700@xiplink.com> (raw)
In-Reply-To: <alpine.LFD.2.03.1309301527270.6331@syhkavp.arg>
On 13-09-30 04:08 PM, Nicolas Pitre wrote:
> On Mon, 30 Sep 2013, Marc Branchaud wrote:
>
>> On 13-09-30 11:52 AM, Nicolas Pitre wrote:
>>> Consider that I have in my Linux kernel tree:
>>>
>>> - a remote branch corresponding to Linus' master tree
>>>
>>> - multiple remote branches corresponding to Linux stable branches
>>>
>>> - a remote for linux-next which is a repo constantly being rebased
>>>
>>> Now all those repositories share the mainline tags from Linus' repo and
>>> they add some more of they own which are not shared. So if they all
>>> have a v3.11 tag that resolve to the same SHA1, then there is
>>> effectively no ambiguity at all and git should not warn at all.
>>
>> Thanks, this example helps very much.
>>
>>> *However* if one of those v3.11 tags does not agree with the others
>>> _then_ I want to be warned about it.
>>
>> Hmmm. What behaviour would you like if you also had some non-Linux remote,
>> say for some driver code or something, that also had a v3.11 tag?
>
> I want git to complain and bail out, maybe suggesting that I should use
> "driver_something/tag/v3.11" to disambiguate the tag.
>
>> I presume
>> you want commands like
>> git checkout -b my-topic v3.11
>> to do the Right Thing, but what's the right thing for you here?
>
> git itself can't know it. So the best git could do is to list
> conflicting tags with the shortest path that makes them unambiguous and
> suggest that I try again with one of them.
>
>>> So having multiple matching tags that do resolve to the same SHA1 across
>>> different remote repositories _is_ the norm and should work
>>> transparently.
>>
>> My suggestion for your example is that if some remote's tags are so
>> important/useful then you're better off importing them into your local tag
>> namespace (e.g. "git fetch Linus refs/tags/*:refs/tags/*"). By making the
>> remote's tags local, you're expressly telling git that they should be
>> considered for DWIMery, git-describe, etc.
>
> Sure, it is probably a good thing semantically to give priority to local
> tags when they exist. However...
>
>> I feel this approach lets us avoid having to somehow teach git which remote's
>> "v3.11" tags are important enough to merit an ambiguity warning and which
>> aren't. Plus you get what I think you want, which is the current behaviour.
>
> But I disagree here. Most people simply won't care about local tags
> since the remote tags are sufficient for what they need.
Good point -- I see where my suggestion was wrong. I think it's worthwhile
to make sure that bare tag names "just work" after a simple clone. Git's
DWIM code already does this for branch names, and it makes sense to extend
that to other ref types in remote namespaces.
> And if they
> have multiple remotes in their repository then it is most likely to be
> different forks of the same project sharing mostly the same tags, and
> where those tags diverge then they're most likely to have different tag
> names as well.
I disagree about the "most likely" part, but it's only a niggle. I agree
with the overall point that disambiguation through SHA1 comparison makes sense.
> So in the large majority of the cases, this v3.11 tag
> will come from one or more remotes and they will refer to the same SHA1,
> so it ought to just work without any special fetch. Also, if I refer to
> v3.11.1 which is a tag that only exists in one of the remote branches
> and not in Linus' remote then it ought to just work as well. That is
> more inline with the current _usage_ behavior even if the flat namespace
> is otherwise a nightmare to sort out when managing remotes.
Agreed.
> Furthermore, git already has some code to detect refname ambiguities:
>
> $ git init && echo "foo" > foo.txt && git add foo.txt
> $ git commit -m "foo" && git tag foo && git branch foo && git log foo
> warning: refname 'foo' is ambiguous.
>
> So adding the extra step to lookup all possible tags and make sure they
> resolve to the same SHA1 should be a logical extension to what's already
> there.
>
> Again, in the cases where there is actually a SHA1 conflict between all
> possible tags that match a tag short-end then listing them and asking the
> user to be more explicit is the right thing to do. But that should be a
> very rare case in practice, and designing for making this case easy is
> the wrong approach.
>
> Instead, the common case of multiple remotes with duplicated tag names
> referring to the same thing _and/or_ multiple remotes with distinct tags
> names is what should be made easy to use with no extra steps.
Again, I don't think that's the common case. I think it's just as likely for
there to be multiple remotes with duplicate tag names that refer to different
objects. However, SHA1-disambiguation covers all these cases.
M.
next prev parent reply other threads:[~2013-09-30 21:14 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-13 2:54 Local tag killer Michael Haggerty
2013-09-13 4:03 ` Junio C Hamano
2013-09-20 22:51 ` Junio C Hamano
2013-09-21 6:42 ` Michael Haggerty
2013-09-21 12:28 ` John Szakmeister
2013-09-24 7:51 ` Jeff King
2013-09-24 13:22 ` Marc Branchaud
2013-09-25 8:22 ` Jeff King
2013-09-25 22:54 ` Nicolas Pitre
2013-09-28 12:20 ` Michael Haggerty
2013-09-28 21:42 ` Johan Herland
2013-09-29 4:29 ` Michael Haggerty
2013-09-29 9:30 ` Johan Herland
2013-09-30 15:24 ` Marc Branchaud
2013-09-30 15:52 ` Nicolas Pitre
2013-09-30 19:16 ` Marc Branchaud
2013-09-30 20:08 ` Nicolas Pitre
2013-09-30 21:14 ` Marc Branchaud [this message]
2013-09-30 22:44 ` Nicolas Pitre
2013-09-30 23:18 ` Jeff King
2013-10-01 3:04 ` Marc Branchaud
2013-10-01 3:28 ` Nicolas Pitre
2013-10-01 12:45 ` Marc Branchaud
2013-10-23 15:50 ` [PATCH 00/15] Change semantics of "fetch --tags" Michael Haggerty
2013-10-23 15:50 ` [PATCH 01/15] t5510: use the correct tag name in test Michael Haggerty
2013-10-23 15:50 ` [PATCH 02/15] t5510: prepare test refs more straightforwardly Michael Haggerty
2013-10-23 18:36 ` Junio C Hamano
2013-10-24 6:49 ` Michael Haggerty
2013-10-24 19:50 ` Junio C Hamano
2013-10-23 15:50 ` [PATCH 03/15] t5510: check that "git fetch --prune --tags" does not prune branches Michael Haggerty
2013-10-23 15:50 ` [PATCH 04/15] api-remote.txt: correct section "struct refspect" Michael Haggerty
2013-10-23 18:43 ` Junio C Hamano
2013-10-24 7:06 ` Michael Haggerty
2013-10-23 15:50 ` [PATCH 05/15] get_ref_map(): rename local variables Michael Haggerty
2013-10-23 18:45 ` Junio C Hamano
2013-10-24 7:24 ` Michael Haggerty
2013-10-23 15:50 ` [PATCH 06/15] ref_remove_duplicates(): avoid redundant bisection Michael Haggerty
2013-10-23 15:50 ` [PATCH 07/15] ref_remove_duplicates(): simplify function Michael Haggerty
2013-10-23 15:50 ` [PATCH 08/15] ref_remove_duplicates(): improve documentation comment Michael Haggerty
2013-10-23 18:47 ` Junio C Hamano
2013-10-23 15:50 ` [PATCH 09/15] builtin/fetch.c: reorder function definitions Michael Haggerty
2013-10-23 15:50 ` [PATCH 10/15] fetch --tags: fetch tags *in addition to* other stuff Michael Haggerty
2013-10-24 20:51 ` Junio C Hamano
2013-10-25 15:08 ` Michael Haggerty
2013-10-28 19:10 ` Junio C Hamano
2013-10-30 4:26 ` Michael Haggerty
2013-10-26 5:10 ` Michael Haggerty
2013-10-23 15:50 ` [PATCH 11/15] fetch --prune: prune only based on explicit refspecs Michael Haggerty
2013-10-24 21:11 ` Junio C Hamano
2013-10-26 6:49 ` Michael Haggerty
2013-10-28 15:08 ` Junio C Hamano
2013-10-23 15:50 ` [PATCH 12/15] query_refspecs(): move some constants out of the loop Michael Haggerty
2013-10-23 15:50 ` [PATCH 13/15] builtin/remote.c: reorder function definitions Michael Haggerty
2013-10-23 15:50 ` [PATCH 14/15] builtin/remote.c:update(): use struct argv_array Michael Haggerty
2013-10-23 15:50 ` [PATCH 15/15] fetch, remote: properly convey --no-prune options to subprocesses Michael Haggerty
2013-10-24 21:17 ` Junio C Hamano
2013-10-23 16:59 ` [PATCH 00/15] Change semantics of "fetch --tags" Junio C Hamano
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