threads / discuss / 13207

showing conflicting merges

Subject: showing conflicting merges

## tl;dr

5 messages between Apr 22, 2008 and Apr 24, 2008.

replies: 4people: 2as markdown or json

Uwe Kleine-König· Apr 22, 2008, 09:12 UTC · lore

Hello,

There is a thread on the linux-arm-kernel ML that discusses handling of merge conflicts with git.[1]

I played around a bit with that and wondered about a few things:

	ukleinek@zentaur:~/gsrc/linux-2.6$ git checkout -b test adf6d34e460387ee3e8f1e1875d
	Switched to a new branch "test"

	ukleinek@zentaur:~/gsrc/linux-2.6$ git merge v2.6.25
	Auto-merged MAINTAINERS
	CONFLICT (delete/modify): drivers/leds/leds-tosa.c deleted in HEAD and modified in v2.6.25. Version v2.6.25 of drivers/leds/leds-tosa.c left in tree.
	Auto-merged drivers/serial/imx.c
	Automatic merge failed; fix conflicts and then commit the result.

Now "git diff --merge" shows:

	diff --cc drivers/leds/leds-tosa.c
	index 7ebecc4,0000000..9e0a188
	...

Shouldn't that better be reversed, i.e. 9e0a188..7ebecc4,0000000?

The resolution was to delete drivers/leds/leds-tosa.c:

	ukleinek@zentaur:~/gsrc/linux-2.6$ git rm drivers/leds/leds-tosa.c
	rm 'drivers/leds/leds-tosa.c'
	rm 'drivers/leds/leds-tosa.c'

	ukleinek@zentaur:~/gsrc/linux-2.6$ git commit
	Created commit 99a64ab: Merge commit 'v2.6.25' into test

Now "git show" doesn't show the conflict resolution as it does for other conflicting merges. Adding -p and/or --cc didn't help either. Looking at the source I think the problem is that diff_tree_combined only shows diffs for paths that are touched by every parent. I'm not sure how I want to have the diff shown, but showing nothing seems wrong. Ideas?

Another thing is that rerere don't record my resolution.

Best regards Uwe

[1] http://thread.gmane.org/gmane.linux.ports.arm.kernel/40654/focus=40656

-- 
Uwe Kleine-König, Software Engineer
Digi International GmbH Branch Breisach, Küferstrasse 8, 79206 Breisach, Germany
Tax: 315/5781/0242 / VAT: DE153662976 / Reg. Amtsgericht Dortmund HRB 13962

Santi Béjar· Apr 22, 2008, 09:49 UTC · re: Uwe Kleine-König · lore

Re: showing conflicting merges

On Tue, Apr 22, 2008 at 11:12 AM, Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com> wrote:

Show 23 quoted lines

> Hello,
>
>  There is a thread on the linux-arm-kernel ML that discusses handling of
>  merge conflicts with git.[1]
>
>  I played around a bit with that and wondered about a few things:
>
>         ukleinek@zentaur:~/gsrc/linux-2.6$ git checkout -b test adf6d34e460387ee3e8f1e1875d
>         Switched to a new branch "test"
>
>         ukleinek@zentaur:~/gsrc/linux-2.6$ git merge v2.6.25
>         Auto-merged MAINTAINERS
>         CONFLICT (delete/modify): drivers/leds/leds-tosa.c deleted in HEAD and modified in v2.6.25. Version v2.6.25 of drivers/leds/leds-tosa.c left in tree.
>         Auto-merged drivers/serial/imx.c
>         Automatic merge failed; fix conflicts and then commit the result.
>
>  Now "git diff --merge" shows:
>
>         diff --cc drivers/leds/leds-tosa.c
>         index 7ebecc4,0000000..9e0a188
>         ...
>
>  Shouldn't that better be reversed, i.e. 9e0a188..7ebecc4,0000000?

It compares the versions in conflict with the version in the working copy.

Show 16 quoted lines

>
>  The resolution was to delete drivers/leds/leds-tosa.c:
>
>         ukleinek@zentaur:~/gsrc/linux-2.6$ git rm drivers/leds/leds-tosa.c
>         rm 'drivers/leds/leds-tosa.c'
>         rm 'drivers/leds/leds-tosa.c'
>
>         ukleinek@zentaur:~/gsrc/linux-2.6$ git commit
>         Created commit 99a64ab: Merge commit 'v2.6.25' into test
>
>  Now "git show" doesn't show the conflict resolution as it does for other
>  conflicting merges.
>  Adding -p and/or --cc didn't help either.  Looking at the source I think
>  the problem is that diff_tree_combined only shows diffs for paths that
>  are touched by every parent.  I'm not sure how I want to have the diff
>  shown, but showing nothing seems wrong.  Ideas?

The combined diff does not show conflicts, it only shows the merged results that are different to all the parents. In this case the merge resolution is to delete one file as in HEAD, so it won't be shown.

If you want to see the conflict resolution you have to recreate the merge and compare with the original merge.

Santi

Uwe Kleine-König· Apr 23, 2008, 06:17 UTC · re: Santi Béjar · lore

Re: showing conflicting merges

Hello Santi,

Santi Béjar wrote:

Show 27 quoted lines

> On Tue, Apr 22, 2008 at 11:12 AM, Uwe Kleine-König
> <Uwe.Kleine-Koenig@digi.com> wrote:
> > Hello,
> >
> >  There is a thread on the linux-arm-kernel ML that discusses handling of
> >  merge conflicts with git.[1]
> >
> >  I played around a bit with that and wondered about a few things:
> >
> >         ukleinek@zentaur:~/gsrc/linux-2.6$ git checkout -b test adf6d34e460387ee3e8f1e1875d
> >         Switched to a new branch "test"
> >
> >         ukleinek@zentaur:~/gsrc/linux-2.6$ git merge v2.6.25
> >         Auto-merged MAINTAINERS
> >         CONFLICT (delete/modify): drivers/leds/leds-tosa.c deleted in HEAD and modified in v2.6.25. Version v2.6.25 of drivers/leds/leds-tosa.c left in tree.
> >         Auto-merged drivers/serial/imx.c
> >         Automatic merge failed; fix conflicts and then commit the result.
> >
> >  Now "git diff --merge" shows:
> >
> >         diff --cc drivers/leds/leds-tosa.c
> >         index 7ebecc4,0000000..9e0a188
> >         ...
> >
> >  Shouldn't that better be reversed, i.e. 9e0a188..7ebecc4,0000000?
> 
> It compares the versions in conflict with the version in the working copy.

I have not checked in the source code, but the output of

	strace -f -e open git diff --merge 2>&1 >/dev/null | grep leds-tosa

seems to contradict that (i.e. there is no output).

	7ebecc4 = v2.6.25:drivers/leds/leds-tosa.c
	9e0a188 = $(git merge-base test v2.6.25):drivers/leds/leds-tosa.c

(Ah, I just see, that's another hint that diff --merge doesn't look in the working copy. The wc has 7ebecc4 which is in the LHS together with 000000 (i.e. the deleted file from HEAD).

Maybe the combined diff format cannot have more than one rev on the RHS?

Show 22 quoted lines

> >  The resolution was to delete drivers/leds/leds-tosa.c:
> >
> >         ukleinek@zentaur:~/gsrc/linux-2.6$ git rm drivers/leds/leds-tosa.c
> >         rm 'drivers/leds/leds-tosa.c'
> >         rm 'drivers/leds/leds-tosa.c'
> >
> >         ukleinek@zentaur:~/gsrc/linux-2.6$ git commit
> >         Created commit 99a64ab: Merge commit 'v2.6.25' into test
> >
> >  Now "git show" doesn't show the conflict resolution as it does for other
> >  conflicting merges.
> >  Adding -p and/or --cc didn't help either.  Looking at the source I think
> >  the problem is that diff_tree_combined only shows diffs for paths that
> >  are touched by every parent.  I'm not sure how I want to have the diff
> >  shown, but showing nothing seems wrong.  Ideas?
> 
> The combined diff does not show conflicts, it only shows the merged
> results that are different to all the parents. In this case the merge
> resolution is to delete one file as in HEAD, so it won't be shown.
> 
> If you want to see the conflict resolution you have to recreate the
> merge and compare with the original merge.

An option to show would be great ...

Best regards Uwe

-- 
Uwe Kleine-König, Software Engineer
Digi International GmbH Branch Breisach, Küferstrasse 8, 79206 Breisach, Germany
Tax: 315/5781/0242 / VAT: DE153662976 / Reg. Amtsgericht Dortmund HRB 13962

Santi Béjar· Apr 24, 2008, 12:51 UTC · re: Uwe Kleine-König · lore

Re: showing conflicting merges

On Wed, Apr 23, 2008 at 8:17 AM, Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com> wrote:

Show 37 quoted lines

> Hello Santi,
>
>
>  Santi Béjar wrote:
>  > On Tue, Apr 22, 2008 at 11:12 AM, Uwe Kleine-König
>  > <Uwe.Kleine-Koenig@digi.com> wrote:
>  > > Hello,
>  > >
>  > >  There is a thread on the linux-arm-kernel ML that discusses handling of
>  > >  merge conflicts with git.[1]
>  > >
>  > >  I played around a bit with that and wondered about a few things:
>  > >
>  > >         ukleinek@zentaur:~/gsrc/linux-2.6$ git checkout -b test adf6d34e460387ee3e8f1e1875d
>  > >         Switched to a new branch "test"
>  > >
>  > >         ukleinek@zentaur:~/gsrc/linux-2.6$ git merge v2.6.25
>  > >         Auto-merged MAINTAINERS
>  > >         CONFLICT (delete/modify): drivers/leds/leds-tosa.c deleted in HEAD and modified in v2.6.25. Version v2.6.25 of drivers/leds/leds-tosa.c left in tree.
>  > >         Auto-merged drivers/serial/imx.c
>  > >         Automatic merge failed; fix conflicts and then commit the result.
>  > >
>  > >  Now "git diff --merge" shows:
>  > >
>  > >         diff --cc drivers/leds/leds-tosa.c
>  > >         index 7ebecc4,0000000..9e0a188
>  > >         ...
>  > >
>  > >  Shouldn't that better be reversed, i.e. 9e0a188..7ebecc4,0000000?
>  >
>  > It compares the versions in conflict with the version in the working copy.
>
>  I have not checked in the source code, but the output of
>
>         strace -f -e open git diff --merge 2>&1 >/dev/null | grep leds-tosa
>
>  seems to contradict that (i.e. there is no output).

The version in the working copy should be 7ebecc4, so there is no need to open it as it is in the index (but maybe I'm wrong).

Show 11 quoted lines

>
>         7ebecc4 = v2.6.25:drivers/leds/leds-tosa.c
>         9e0a188 = $(git merge-base test v2.6.25):drivers/leds/leds-tosa.c
>
>  (Ah, I just see, that's another hint that diff --merge doesn't look in
>  the working copy.  The wc has 7ebecc4 which is in the LHS together with
>  000000 (i.e. the deleted file from HEAD).
>
>  Maybe the combined diff format cannot have more than one rev on the RHS?
>
>

FWIU --merge is an option for git-rev-list (and alike, git log, gitk...). I don't know its meaning in this case. It shoud be juts:

$git diff

that currently says in this case:

$ git diff
* Unmerged path file1

In this case:

	echo a >file1 &&
	git add file1 &&
	git commit -m initial &&
	git checkout -b a1 master &&
	git rm file1 &&
	git commit -m a &&
	git checkout -b b1 master &&
	echo  b> file1 &&
	git add file1 &&
	git commit -m b1 &&
	git checkout a1 &&
	git merge b1

The merge output is: Merging HEAD with b1 Merging: 3231a8a a ace6b2d b1 found 1 common ancestor(s): f43806f initial CONFLICT (delete/modify): file1 deleted in HEAD and modified in b1. Version b1 of file1 left in tree. Automatic merge failed; fix conflicts and then commit the result.

$ git ls-files -s 100644 78981922613b2afb6025042ff6bd878ac1994e85 1 file1 100644 61780798228d17af2d34fce4cfbdf35556832472 3 file1

$ git diff [-1 | -2 | -3]
* Unmerged path file1

$ git diff --merge diff --cc file1 index 6178079,0000000..7898192 mode 100644,000000..100644

--- a/file1
+++ b/file1
@@@ -1,1 -1,0 +1,1 @@@
- b
++a

that does not make sense.

Maybe something as?

$ git diff
diff --cc file1
index 0000000,6178079..0000000
mode 000000,100644..0000000
--- /dev/null
+++ b/file1

But I don't really know what to expect in this case.

Santi

Santi Béjar· Apr 24, 2008, 13:08 UTC · re: Santi Béjar · lore

Re: showing conflicting merges

On Thu, Apr 24, 2008 at 2:51 PM, Santi Béjar <sbejar@gmail.com> wrote:

Show 100 quoted lines

> On Wed, Apr 23, 2008 at 8:17 AM, Uwe Kleine-König
>
> <Uwe.Kleine-Koenig@digi.com> wrote:
>  > Hello Santi,
>  >
>  >
>  >  Santi Béjar wrote:
>  >  > On Tue, Apr 22, 2008 at 11:12 AM, Uwe Kleine-König
>  >  > <Uwe.Kleine-Koenig@digi.com> wrote:
>  >  > > Hello,
>  >  > >
>  >  > >  There is a thread on the linux-arm-kernel ML that discusses handling of
>  >  > >  merge conflicts with git.[1]
>  >  > >
>  >  > >  I played around a bit with that and wondered about a few things:
>  >  > >
>  >  > >         ukleinek@zentaur:~/gsrc/linux-2.6$ git checkout -b test adf6d34e460387ee3e8f1e1875d
>  >  > >         Switched to a new branch "test"
>  >  > >
>  >  > >         ukleinek@zentaur:~/gsrc/linux-2.6$ git merge v2.6.25
>  >  > >         Auto-merged MAINTAINERS
>  >  > >         CONFLICT (delete/modify): drivers/leds/leds-tosa.c deleted in HEAD and modified in v2.6.25. Version v2.6.25 of drivers/leds/leds-tosa.c left in tree.
>  >  > >         Auto-merged drivers/serial/imx.c
>  >  > >         Automatic merge failed; fix conflicts and then commit the result.
>  >  > >
>  >  > >  Now "git diff --merge" shows:
>  >  > >
>  >  > >         diff --cc drivers/leds/leds-tosa.c
>  >  > >         index 7ebecc4,0000000..9e0a188
>  >  > >         ...
>  >  > >
>  >  > >  Shouldn't that better be reversed, i.e. 9e0a188..7ebecc4,0000000?
>  >  >
>  >  > It compares the versions in conflict with the version in the working copy.
>  >
>  >  I have not checked in the source code, but the output of
>  >
>  >         strace -f -e open git diff --merge 2>&1 >/dev/null | grep leds-tosa
>  >
>  >  seems to contradict that (i.e. there is no output).
>
>  The version in the working copy should be 7ebecc4, so there is no need
>  to open it as it is in the index (but maybe I'm wrong).
>
>
>  >
>  >         7ebecc4 = v2.6.25:drivers/leds/leds-tosa.c
>  >         9e0a188 = $(git merge-base test v2.6.25):drivers/leds/leds-tosa.c
>  >
>  >  (Ah, I just see, that's another hint that diff --merge doesn't look in
>  >  the working copy.  The wc has 7ebecc4 which is in the LHS together with
>  >  000000 (i.e. the deleted file from HEAD).
>  >
>  >  Maybe the combined diff format cannot have more than one rev on the RHS?
>  >
>  >
>
>  FWIU --merge is an option for git-rev-list (and alike, git log,
>  gitk...). I don't know its meaning in this case. It shoud be juts:
>
>  $git diff
>
>  that currently says in this case:
>
>  $ git diff
>  * Unmerged path file1
>
>  In this case:
>
>         echo a >file1 &&
>         git add file1 &&
>         git commit -m initial &&
>         git checkout -b a1 master &&
>         git rm file1 &&
>         git commit -m a &&
>         git checkout -b b1 master &&
>         echo  b> file1 &&
>         git add file1 &&
>         git commit -m b1 &&
>         git checkout a1 &&
>         git merge b1
>
>  The merge output is:
>  Merging HEAD with b1
>  Merging:
>  3231a8a a
>  ace6b2d b1
>  found 1 common ancestor(s):
>  f43806f initial
>  CONFLICT (delete/modify): file1 deleted in HEAD and modified in b1.
>  Version b1 of file1 left in tree.
>
> Automatic merge failed; fix conflicts and then commit the result.
>
>  $ git ls-files -s
>  100644 78981922613b2afb6025042ff6bd878ac1994e85 1       file1
>  100644 61780798228d17af2d34fce4cfbdf35556832472 3       file1
>
>  $ git diff [-1 | -2 | -3]
>  * Unmerged path file1

Actually only: git diff git diff -2 git diff -3

for:
$ git diff -1
* Unmerged path file1

diff --git a/file1 b/file1
index 7898192..c9c6af7 100644
--- a/file1
+++ b/file1
@@ -1 +1 @@
-a
+b1

but "-2" and "-3" do the same for different reasons

-2) theres is no "2" in the index
-3) is equal to the wc file1

so both output the same:
* Unmerged path file1

and I still think "git diff" has to output something else than
"*Unmerged path file1".

>
>  $ git diff --merge
>  diff --cc file1
>  index 6178079,0000000..7898192
>  mode 100644,000000..100644
>  --- a/file1
>  +++ b/file1
>  @@@ -1,1 -1,0 +1,1 @@@
>  - b
>  ++a
>
>  that does not make sense.
>
>  Maybe something as?
>
>  $ git diff
>  diff --cc file1
>  index 0000000,6178079..0000000
>  mode 000000,100644..0000000
>  --- /dev/null
>  +++ b/file1
>
>  But I don't really know what to expect in this case.
>
>  Santi
>