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From: "Rubén Justo" <rjusto@gmail.com>
To: Victoria Dye <vdye@github.com>, Git List <git@vger.kernel.org>
Cc: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"Taylor Blau" <me@ttaylorr.com>
Subject: Re: [PATCH 2/2] branch: clear target branch configuration before copying or renaming
Date: Sun, 20 Nov 2022 10:20:31 +0100	[thread overview]
Message-ID: <042c18df-deb6-6214-2d49-c214a872e1c1@gmail.com> (raw)
In-Reply-To: <8457ad4c-51c7-4c2d-8dbf-02a60045d288@github.com>

On 17-nov-2022 18:10:52, Victoria Dye wrote:
> Rubén Justo wrote:
> > There are two problems with -m (rename) and -c (copy) branch operations.
> > 
> >  1. If we force-rename or force-copy a branch to overwrite another
> >  branch that already has configuration, the resultant branch ends up
> >  with the source configuration (if any) mixed with the configuration for
> >  the overwritten branch.
> > 
> > 	$ git branch upstream
> > 	$ git branch -t foo upstream  # foo has tracking configuration
> > 	$ git branch bar              # bar has not
> > 	$ git branch -M bar foo       # force-rename bar to foo
> > 	$ git config branch.foo.merge # must return clear
> > 	refs/heads/upstream
> 
> What happens if 'bar' has tracking info? You mentioned that the
> configuration is "mixed" - does that mean 'foo' would have both the original
> 'foo's tracking info *and* 'bar's? 

Of course :-).  My reasoning here is considering 'no tracking' as
tracking information, hence the 'if any'.  I think that the unexpected
functioning this patch is trying to resolve is more obvious having an
unexpected tracking information if we rename a branch /with 'no
tracking'/, overwriting (-M) a branch that already has tracking
information.

> I wasn't sure whether "transfer the source's tracking information to the
> destination" was the desired behavior, but it looks like it is (per
> 52d59cc6452 (branch: add a --copy (-c) option to go with --move (-m),
> 2017-06-18)). Given that, I agree this is the right fix for the issue you've
> identified.

Yes, a reference to that commit is a good information to have in the
message.  But I prefer to not refer to it as I don't think that commit
is responsible or explains this unexpected result, though I cc'ed Ævar
;-)

The design decisions in branch.c and config.c have brought us to this
unexpected result, which just need to be addressed. IMHO

> >  
> > +test_expect_success 'git branch -M inherites clean tracking setup' '
> 
> s/inherites/inherits

Oops, thanks.

> > +	test_when_finished git branch -D moved &&
> > +	git branch -t main-tracked main &&
> > +	git branch non-tracked &&
> > +	git branch -M main-tracked moved &&
> > +	git branch --unset-upstream moved &&
> > +	git branch -M non-tracked moved &&
> > +	test_must_fail git branch --unset-upstream moved
> 
> If I'm reading this correctly, the test doesn't actually demonstrate that
> 'git branch -M' cleans up the tracking info, since 'moved' never has any
> tracking info immediately before 'git branch -M'. The test could also be
> more precise by verifying the upstream name matches. What about something
> like this?
> 
> 	test_when_finished git branch -D moved &&
> 	git branch -t main-tracked main &&
> 	git branch non-tracked &&
> 
> 	# `moved` doesn't exist, so it starts with no tracking info
> 	echo main >expect &&
> 	git branch -M main-tracked moved &&
> 	git rev-parse --abbrev-ref moved@{upstream} >actual &&
> 	test_cmp expect actual &&
> 
> 	# At this point, `moved` is tracking `main`
> 	git branch -M non-tracked moved &&
> 	test_must_fail git rev-parse --abbrev-ref moved@{upstream}

You are right, good eye.  Thanks.  That first '--unset-upstream'
eliminates the possible undesired inherited tracking info.  Removing it
is needed to make the test meaningful.  'rev-parse' is a good change,
but as the test is not testing that '-M' works as expected but doesn't
work in the unexpected way the message describes, I don't think we need
it here, imho.

> s/inherites/inherits (same typo as before, just pointing it out so it's
> easier to find)

Oops, thanks again.

> > +	test_when_finished git branch -D copiable copied &&
> > +	git branch -t copiable main &&
> > +	git branch -C copiable copied &&
> > +	git branch --unset-upstream copied &&
> > +	git branch -C copied copiable &&
> > +	test_must_fail git branch --unset-upstream copiable
> 
> This doesn't have the same issue as the other test (since 'copied' has no
> tracking but 'copiable' does before both 'git branch -C' calls), but it
> would still be nice to use the 'git rev-parse --abbrev-ref
> <branch>@{upstream}' for more precision here. 

I still prefer the test_must_fail for '--unset-upstream', for the same
reasons that in the previous hunk.  I also think it improves
t3200-branch.sh.

Something like...

--- >8 ---

Thank you!

 t/t3200-branch.sh | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index c3b3d11c28..ba959a82de 100755
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -218,17 +218,16 @@ test_expect_success 'git branch -M should leave orphaned HEAD alone' '
 	)
 '
 
-test_expect_success 'git branch -M inherites clean tracking setup' '
+test_expect_success 'git branch -M inherits clean tracking setup' '
 	test_when_finished git branch -D moved &&
 	git branch -t main-tracked main &&
 	git branch non-tracked &&
-	git branch -M main-tracked moved &&
 	git branch --unset-upstream moved &&
 	git branch -M non-tracked moved &&
 	test_must_fail git branch --unset-upstream moved
 '
 
-test_expect_success 'git branch -C inherites clean tracking setup' '
+test_expect_success 'git branch -C inherits clean tracking setup' '
 	test_when_finished git branch -D copiable copied &&
 	git branch -t copiable main &&
 	git branch -C copiable copied &&


  reply	other threads:[~2022-11-20  9:20 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-17  1:33 [PATCH 0/2] branch: fix some malfunctions in -m/-c Rubén Justo
2022-11-17  1:36 ` [PATCH 1/2] branch: force-copy a branch to itself via @{-1} is a no-op Rubén Justo
2022-11-17 22:18   ` Victoria Dye
2022-11-20  8:10     ` Rubén Justo
2022-11-18  3:58   ` Ævar Arnfjörð Bjarmason
2022-11-20  9:34     ` Rubén Justo
2022-11-17  1:44 ` [PATCH 2/2] branch: clear target branch configuration before copying or renaming Rubén Justo
2022-11-18  2:10   ` Victoria Dye
2022-11-20  9:20     ` Rubén Justo [this message]
2022-11-20 22:10       ` Victoria Dye
2022-11-21 23:13         ` Rubén Justo
2022-11-18  4:51   ` Ævar Arnfjörð Bjarmason
2022-11-18 16:36     ` Victoria Dye
2022-11-18 18:12       ` Ævar Arnfjörð Bjarmason
2022-11-20 14:55         ` Rubén Justo

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