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From: Junio C Hamano <gitster@pobox.com>
To: Johannes Sixt <j6t@kdbg.org>
Cc: git@vger.kernel.org
Subject: Re: [PATCH 7/7] push: document --lockref
Date: Sun, 14 Jul 2013 12:17:46 -0700	[thread overview]
Message-ID: <7v61wdgdd1.fsf@alter.siamese.dyndns.org> (raw)
In-Reply-To: <51E1B5DB.9080904@kdbg.org> (Johannes Sixt's message of "Sat, 13 Jul 2013 22:17:31 +0200")

Johannes Sixt <j6t@kdbg.org> writes:

> All you have been saying is that you find your
>
>    git push --lockref there topic
>
> is more useful than my
>
>    git push --lockref there +topic
>
> You are trading crystal clear semantics to save users ONE character to
> type. IMO, it's a bad deal.

Think how you would explain the option in a tutorial for those who
use the push.default=simple semantics.

"""
	You usually do

		$ git pull [--rebase]

	to integrate with the shared branch and push it back with

		$ git push

	Sometimes the project wants to rewind the tip of such a
	shared branch (perhaps a bad commit included inappropriate
	material that should not be in the history).  You cordinate
	the decision to do such a rewinding with others in the
	project, you "git rebase [-i]" to prepare a replacement
	history, and then try to push tthe result out.  However

		$ git push

	will fail, because this does not fast-forward.  But you and
	your colleagues agreed that the project wants this new
	history!

        With older Git, the only way to make this push go through
        was to "--force" it.  That will risk losing work of other
        people who were not aware of the collective decision to
        rewind this shared branch [discussion of lockref safety
        comes here].  Instead you can use

		$ git push --lockref

"""

How does the last line look with your "--lockref does not override
must-fast-forward" proposal?

"""

	If your current branch is configured to push to update the
	branch 'frotz' of the remote 'origin' (replace these two
	appropriately for your situation), you would say:

		$ git push --lockref origin +HEAD:frotz

"""

How is that crystal clear?  You are just making things more complex
and harder to learn (I was tempted to add "for no good reason" here,
but I'd assume that probably you haven't explained your reasons well
enough to be heard).

> The crystal clear semantics would be:
>
>  - to override no-ff safety, use +refspec;
>
>  - to override "mismatch" safety, do not use --lockref/use --no-lockref;
>
>  - do not use --force unless you know the consequences.

Alternatively, this is also crystal clear

 - to use the full safety, do not use anything funky

 - to push a history that does not fast-forward safely, use
   --lockref

 - do not use --force unless you know the consequences.

and that is what the patch does.

> I actually think that by implying allow-no-ff in --lockref, you are
> hurting users who have configured a push refspec without a + prefix:
> They suddenly do not get the push denied when it is not a fast-forward
> anymore.

Of course, that is why you should not use --lockref when you do not
have to.  It is a tool to loosen "must fast-forward" in a more
controlled way than the traditional "--force".

 For example, when you have
>
>     [remote "ko"]
>         push = master
>         push = +pu
>
> and you accidentally rewound master before the point that is already
> published, then
>
>    git push --lockref ko
>
> will happily push the rewound master.

Yes, and I am not (and I do expect nobody is) stupid to use --lockref
in such a situation where there is no need to do so.

  reply	other threads:[~2013-07-14 19:18 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-02 20:57 [RFD] Making "git push [--force/--delete]" safer? Junio C Hamano
2013-07-02 22:55 ` Johan Herland
2013-07-03  6:34   ` Johan Herland
2013-07-03  8:49     ` Junio C Hamano
2013-07-03 10:00       ` Johan Herland
2013-07-03 10:06         ` Jonathan del Strother
2013-07-03 10:11           ` Johan Herland
2013-07-03 10:50             ` Michael Haggerty
2013-07-03 12:06               ` Johannes Sixt
2013-07-03 19:53                 ` Junio C Hamano
2013-07-04  5:37                   ` Johannes Sixt
2013-07-04  5:46                     ` Junio C Hamano
2013-07-03 19:50           ` Junio C Hamano
2013-07-03 20:18             ` Junio C Hamano
2013-07-03 19:48         ` Junio C Hamano
2013-07-09 19:53 ` [PATCH 0/7] safer "push --force" with compare-and-swap Junio C Hamano
2013-07-09 19:53   ` [PATCH 1/7] cache.h: move remote/connect API out of it Junio C Hamano
2013-07-09 19:53   ` [PATCH 2/7] builtin/push.c: use OPT_BOOL, not OPT_BOOLEAN Junio C Hamano
2013-07-09 19:53   ` [PATCH 3/7] push: beginning of compare-and-swap "force/delete safety" Junio C Hamano
2013-07-09 19:53   ` [PATCH 4/7] remote.c: add command line option parser for --lockref Junio C Hamano
2013-07-16 22:13     ` John Keeping
2013-07-17 17:06       ` Junio C Hamano
2013-07-17 17:09       ` Junio C Hamano
2013-07-09 19:53   ` [PATCH 5/7] push --lockref: implement logic to populate old_sha1_expect[] Junio C Hamano
2013-07-09 19:53   ` [PATCH 6/7] t5533: test "push --lockref" Junio C Hamano
2013-07-09 19:53   ` [PATCH 7/7] push: document --lockref Junio C Hamano
2013-07-09 20:17     ` Aaron Schrab
2013-07-09 20:39       ` Junio C Hamano
2013-07-09 20:24     ` Johannes Sixt
2013-07-09 20:37       ` Junio C Hamano
2013-07-09 20:55         ` Johannes Sixt
2013-07-09 22:09           ` Junio C Hamano
2013-07-09 23:08             ` Junio C Hamano
2013-07-11 21:10               ` Johannes Sixt
2013-07-11 21:57                 ` Junio C Hamano
2013-07-11 22:14                 ` Junio C Hamano
2013-07-12 17:21                   ` Johannes Sixt
2013-07-12 17:40                     ` Junio C Hamano
2013-07-12 20:00                       ` Johannes Sixt
2013-07-12 21:19                         ` Junio C Hamano
2013-07-13  6:52                           ` Johannes Sixt
2013-07-13 18:14                             ` Junio C Hamano
2013-07-13 20:08                               ` Junio C Hamano
2013-07-13 21:11                                 ` Johannes Sixt
2013-07-14 14:28                                 ` John Keeping
2013-07-13 20:17                               ` Johannes Sixt
2013-07-14 19:17                                 ` Junio C Hamano [this message]
2013-07-14 20:21                                   ` Johannes Sixt
2013-07-14 20:34                                     ` Jonathan Nieder
2013-07-14 20:49                                       ` Jonathan Nieder
2013-07-14 20:59                                       ` Johannes Sixt
2013-07-14 21:28                                         ` Jonathan Nieder
2013-07-15  4:10                                           ` Junio C Hamano
2013-07-15  4:44                                             ` Jonathan Nieder
2013-07-15 15:37                                               ` Junio C Hamano
2013-07-15 20:30                                         ` Johannes Sixt
2013-07-15  3:50                                     ` Junio C Hamano
2013-07-15 15:47                                       ` Default expectation of --lockref Junio C Hamano
2013-07-15 20:27                                       ` [PATCH 7/7] push: document --lockref Johannes Sixt
2013-07-09 21:37         ` Marc Branchaud
2013-07-09 20:27     ` Michael Haggerty
2013-07-09 20:42       ` Junio C Hamano

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