Re: Re: Possible regression in master? (submodules without a "master" branch)
On Fri, Mar 28, 2014 at 12:21:23AM +0100, Johan Herland wrote: > On Thu, Mar 27, 2014 at 9:27 PM, Heiko Voigt wrote: > > On Thu, Mar 27, 2014 at 12:39:03PM -0700, Junio C Hamano wrote: > >> There is this bit for "update" in git-submodule.txt: > >> > >> For updates that clone missing submodules, checkout-mode > >> updates will create submodules with detached HEADs; all other > >> modes will create submodules with a local branch named after > >> submodule..branch. > >> > >> … > >> So the proposed change is to make the part before semicolon true? > >> If we are not newly cloning (because we already have it), if the > >> submodule..branch is not set *OR* refers to a branch that > >> does not even exist, shouldn't we either (1) abort as an error, > >> or (2) do the same and detach? > > > > I would expect "(1) abort as an error" since the user is not > > getting what he would expect. Branch-attachment is mostly a function of submodule..update, not a function of submodule..branch. We could certainly interpret a missing submodule..branch as: * Use the subproject's HEAD for the initial clone (clear start_point in cmd_update if submodule."$name".branch is not set). * Don't change the branch name on subsequent local updates (what we already do). * Do $something if the user tries a --remote update. I just don't know what that $something should be. > FWIW, here is the behaviour I would expect from "git submodule > update": > > - In checkout-mode, if submodule..branch is not set, we > should _always_ detach. Whether or not the submodule is already > cloned does not matter. Agreed, checkout-mode should *always* detach the submodule's HEAD. > - In rebase/merge-mode, if submodule..branch is not set, we > should _always_ abort with an error. Why? Can't we mimic clone and use the remote's HEAD (for --remote updates)? That seems more intuitive to me. For local updates, we're just integrating the gitlinked commit with the submodule's HEAD, and you don't need submodule..branch for that at all. > - If submodule..branch is set - but the branch it refers to > does not exist - we should _always_ abort with an error. The current > checkout/rebase/merge-mode does not matter. Sounds good to me, and should match the current functionality. > In other words, submodule..branch is _necessary_ in > rebase/merge mode, but _optional_ in checkout-mode (its absence > indicating that we should detach). The main trigger for “we should detach” is the update mode (checkout-mode detaches, all others integrate with the submodule's HEAD (without changing submodule branches). You only need submodule..branch for determining which *remote* commit you're trying to integrate (or clone from). HEAD, master, and “die screaming” all sound like reasonable defaults in that case. Deciding between them is a policy/UI decision, not a technical decision. > >> > gitmodules(5) is pretty clear that 'submodule..branch' > >> > defaults to master (and not upstream's HEAD), do we want to > >> > adjust this at the same time? > >> > >> That may be likely. If the value set to a configuration variable > >> causes an established behaviour of a program change a lot, > >> silently defaulting that variable to something many people are > >> expected to have (e.g. 'master') would likely to cause a > >> usability regression. > > > > IMO this branch configuration should completely ignored in the > > default, non --remote, usage. Since we simply checkout a specific > > SHA1 in this case, that should be possible. > > Yes. Checkout-mode with no submodule..branch configured should > always detach. Except for the initial clone (where it's easy to fix), submodule..branch *is* ignored in non --remote updates. Cheers, Trevor -- This email may be signed or encrypted with GnuPG (http://www.gnupg.org). For more information, see http://en.wikipedia.org/wiki/Pretty_Good_Privacy signature.asc Description: OpenPGP digital signature
Re: Re: Possible regression in master? (submodules without a "master" branch)
(Thanks to all of you for picking this up and more or less resolving
it while I was away from email for a few hours...)
On Thu, Mar 27, 2014 at 9:27 PM, Heiko Voigt wrote:
> On Thu, Mar 27, 2014 at 12:39:03PM -0700, Junio C Hamano wrote:
>> "W. Trevor King" writes:
>> > On Thu, Mar 27, 2014 at 06:31:27PM +0100, Jens Lehmann wrote:
>> >> Am 27.03.2014 18:16, schrieb Junio C Hamano:
>> >> > Johan Herland writes:
>> >> >> I just found a failure to checkout a project with submodules where
>> >> >> there is no explicit submodule branch configuration, and the
>> >> >> submodules happen to not have a "master" branch:
>> >> >>
>> >> >> git clone git://gitorious.org/qt/qt5.git qt5
>> >> >> cd qt5
>> >> >> git submodule init qtbase
>> >> >> git submodule update
>> >> >>
>> >> >> In current master, the last command fails with the following output:
>> >> >
>> >> > ... and with a bug-free system, what does it do instead? Just clone
>> >> > 'qtbase' and make a detached-head checkout at the commit recorded in
>> >> > the superproject's tree, or something else?
>> >>
>> >> After reverting 23d25e48f5ead73 on current master it clones 'qtbase'
>> >> nicely with a detached HEAD.
...which is exactly the behaviour I (and the Qt project - I assume) expected.
>> > Fixing this for initial update clone is pretty easy, we just need to
>> > unset start_point before calling module_clone if
>> > submodule..branch is not set.
>>
>> There is this bit for "update" in git-submodule.txt:
>>
>> For updates that clone missing submodules, checkout-mode updates
>> will create submodules with detached HEADs; all other modes will
>> create submodules with a local branch named after
>> submodule..branch.
>>
>> [side note] Isn't that a typo of submodule..branch?
>
> Yep, thats is a typo. Trevor will you fix that as well? Or how should be
> do that? Since its just such a small change.
>
>> So the proposed change is to make the part before semicolon true?
>> If we are not newly cloning (because we already have it), if the
>> submodule..branch is not set *OR* refers to a branch that does
>> not even exist, shouldn't we either (1) abort as an error, or (2) do
>> the same and detach?
>
> I would expect "(1) abort as an error" since the user is not getting what
> he would expect.
FWIW, here is the behaviour I would expect from "git submodule update":
- In checkout-mode, if submodule..branch is not set, we should
_always_ detach. Whether or not the submodule is already cloned does
not matter.
- In rebase/merge-mode, if submodule..branch is not set, we
should _always_ abort with an error.
- If submodule..branch is set - but the branch it refers to
does not exist - we should _always_ abort with an error. The current
checkout/rebase/merge-mode does not matter.
In other words, submodule..branch is _necessary_ in rebase/merge
mode, but _optional_ in checkout-mode (its absence indicating that we
should detach).
>> > However, that's just going to
>> > push remote branch ambiguity problems back to the --remote update
>> > functionality. What should happen when submodule..branch is not
>> > set and you run a --remote update, which has used:
>> >
>> > git rev-parse "${remote_name}/${branch}"
>> >
>> > since the submodule..branch setting was introduced in 06b1abb
>> > (submodule update: add --remote for submodule's upstream changes,
>> > 2012-12-19)?
>>
>> Isn't --remote about following one specific branch the user who
>> issues that command has in mind? If you as the end user did not
>> give any indication which branch you meant, e.g. by leaving the
>> submodule..branch empty, shouldn't that be diagnosed as an
>> error?
>
> Well to simplify things there was this fallback to origin/master
> (similar to the master branch we create on init) since that is a branch
> which many projects have.
I think the analogy to "the master branch we create on init" is false.
A better analogy is running "git pull" or "git pull -rebase" in a
branch where branch..merge has not yet been set. And this
currently fails with "Please specify which branch you want to merge
with." So I would be inclined to agree with Junio here: We should
error out.
> E.g. for the users that share one central
> server and just directly commit, push and pull to/from master. They
> would have an easy way to start working in a submodule, by simply saying
> --remote and then committing to master. At least that is what I
> imagine.
If there are compelling arguments for providing a default fallback
(and I'm not sure the above argument is enough), I say we should
rather follow clone's lead, and use the submodule's upstream's HEAD,
instead of blindly assuming "origin/master" to be present. I expect in
most cases where "origin/master" happens to be the Right Answer, using
the submodule's upstream's HEAD will yield the same result.
>> > gitmodules(5) is pretty clear that 'submodule..branch' defaults
>> > to master (and not upstream's HEAD), do we want to adjust this at the
>>
Re: Re: Possible regression in master? (submodules without a "master" branch)
On Thu, Mar 27, 2014 at 12:39:03PM -0700, Junio C Hamano wrote:
> "W. Trevor King" writes:
>
> > On Thu, Mar 27, 2014 at 06:31:27PM +0100, Jens Lehmann wrote:
> >> Am 27.03.2014 18:16, schrieb Junio C Hamano:
> >> > Johan Herland writes:
> >> >
> >> >> I just found a failure to checkout a project with submodules where
> >> >> there is no explicit submodule branch configuration, and the
> >> >> submodules happen to not have a "master" branch:
> >> >>
> >> >> git clone git://gitorious.org/qt/qt5.git qt5
> >> >> cd qt5
> >> >> git submodule init qtbase
> >> >> git submodule update
> >> >>
> >> >> In current master, the last command fails with the following output:
> >> >
> >> > ... and with a bug-free system, what does it do instead? Just clone
> >> > 'qtbase' and make a detached-head checkout at the commit recorded in
> >> > the superproject's tree, or something else?
> >>
> >> After reverting 23d25e48f5ead73 on current master it clones 'qtbase'
> >> nicely with a detached HEAD.
> >
> > Fixing this for initial update clone is pretty easy, we just need to
> > unset start_point before calling module_clone if
> > submodule..branch is not set.
>
> There is this bit for "update" in git-submodule.txt:
>
> For updates that clone missing submodules, checkout-mode updates
> will create submodules with detached HEADs; all other modes will
> create submodules with a local branch named after
> submodule..branch.
>
> [side note] Isn't that a typo of submodule..branch?
Yep, thats is a typo. Trevor will you fix that as well? Or how should be
do that? Since its just such a small change.
> So the proposed change is to make the part before semicolon true?
> If we are not newly cloning (because we already have it), if the
> submodule..branch is not set *OR* refers to a branch that does
> not even exist, shouldn't we either (1) abort as an error, or (2) do
> the same and detach?
I would expect "(1) abort as an error" since the user is not getting what
he would expect.
> > However, that's just going to
> > push remote branch ambiguity problems back to the --remote update
> > functionality. What should happen when submodule..branch is not
> > set and you run a --remote update, which has used:
> >
> > git rev-parse "${remote_name}/${branch}"
> >
> > since the submodule..branch setting was introduced in 06b1abb
> > (submodule update: add --remote for submodule's upstream changes,
> > 2012-12-19)?
>
> Isn't --remote about following one specific branch the user who
> issues that command has in mind? If you as the end user did not
> give any indication which branch you meant, e.g. by leaving the
> submodule..branch empty, shouldn't that be diagnosed as an
> error?
Well to simplify things there was this fallback to origin/master
(similar to the master branch we create on init) since that is a branch
which many projects have. E.g. for the users that share one central
server and just directly commit, push and pull to/from master. They
would have an easy way to start working in a submodule, by simply saying
--remote and then committing to master. At least that is what I
imagine.
> > gitmodules(5) is pretty clear that 'submodule..branch' defaults
> > to master (and not upstream's HEAD), do we want to adjust this at the
> > same time?
>
> That may be likely. If the value set to a configuration variable
> causes an established behaviour of a program change a lot, silently
> defaulting that variable to something many people are expected to
> have (e.g. 'master') would likely to cause a usability regression.
IMO this branch configuration should completely ignored in the default,
non --remote, usage. Since we simply checkout a specific SHA1 in this
case, that should be possible.
Cheers Heiko
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