[BUG] - git rebase -i performs rebase when it shouldn't?

[BUG] - git rebase -i performs rebase when it shouldn't?

[Eugene Sajine]

Hi,


In case of this situation

       A  master
        \
         B  next
          \
           C  topic


$ git rebase --onto master topic
First, rewinding head to replay your work on top of it...
fatal: Not a range.
Nothing to do.

Which is OK.

When I fired up interactive rebase, it printed me “noop”, so I was
expecting it to do nothing and exited the vi, without deleting this
"noop". But it did performed some operation and I actually have commit
C lost, with topic pointing to the same commit as master.

$ git rebase -i --onto master topic
Successfully rebased and updated refs/heads/topic.

I believe this is wrong.


Thanks,
Eugene

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Jeff King]

On Fri, Apr 09, 2010 at 03:35:42PM -0400, Eugene Sajine wrote:

> In case of this situation
> 
>        A  master
>         \
>          B  next
>           \
>            C  topic
> 
> 
> $ git rebase --onto master topic
> First, rewinding head to replay your work on top of it...
> fatal: Not a range.
> Nothing to do.
> 
> Which is OK.

I think this doesn't do quite what you thought. It's true there is
"nothing to do" as in "nothing to apply", but it _did_ in fact rewind
topic back to "master".

You seem to be thinking that

  git rebase --onto master topic

means "rebase everything from master to topic onto master". It doesn't.
That would be:

  git rebase master topic

or, if you are already on topic, just

  git rebase master

The "--onto" option takes an argument, which says "put the commits on
top of here, even though it was not the upstream base otherwise
specified". So what your command does is say "using the current branch
(which is topic), take everything built on top of topic (which is
nothing), and rebuild it on top of master".

So no, it's not a bug. Yes, it's a terrible interface. There is really
no reason IMHO for rebase to take a "which branch to operate on"
argument at all. It should just operate on HEAD, like merge does. If you
want to merge on a different branch, you "git checkout" that branch
first.

That would have made your error less likely, because you would have had
no reason to think you needed to say "topic" at all.

-Peff

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Junio C Hamano]

Jeff King <peff@peff.net> writes:

> So no, it's not a bug. Yes, it's a terrible interface. There is really
> no reason IMHO for rebase to take a "which branch to operate on"
> argument at all. It should just operate on HEAD, like merge does. If you
> want to merge on a different branch, you "git checkout" that branch
> first.

I guess it's my turn to say "sorry it was my fault made in pre-maintainer
days around 59e6b23 ([PATCH] git-rebase-script: rebase local commits to
new upstream head., 2005-06-25).

I used to religiously rebase slushy topics that are not in any stable
integration branches (we used to have only 'master' and 'pu'), and

	git rebase master foo
        git rebase master bar
        git rebase master baz

was far easier to type than

	git checkout foo && git rebase master
	git checkout bar && git rebase master
	git checkout baz && git rebase master

when you have many topics.  Especially because the exact keystroke
sequences are:

	git rebase master foo ENTER
	^P (recall the last line) ^W (delete the last word) bar ENTER
	^P ^W baz ENTER

for the former.  Of course, I can do the same with the latter interface

	sh -c 'git checkout "$1" && git rebase master' - foo ENTER
	^P (recall the last line) ^W (delete the last word) bar ENTER
	^P ^W baz ENTER

so that is not a very good excuse, but at least now people know where it
came from ;-)

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Jeff King]

On Fri, Apr 09, 2010 at 09:39:22PM -0700, Junio C Hamano wrote:

> I used to religiously rebase slushy topics that are not in any stable
> integration branches (we used to have only 'master' and 'pu'), and
> 
> 	git rebase master foo
>         git rebase master bar
>         git rebase master baz
> 
> was far easier to type than
> 
> 	git checkout foo && git rebase master
> 	git checkout bar && git rebase master
> 	git checkout baz && git rebase master

Interestingly, I faced a similar problem a few months ago. I have many
half-finished topics, and I aggressively rebase them against master
(mostly to see and fix conflicts early). But I wrote a script so I don't
have to type each one individually. :)

It uses for-each-ref with a filter to get the list of topics, and then
rebases in a loop.  It just barfs when a rebase has conflicts, which is
OK. You fix them, finish the rebase, and restart the script, which just
skips over the noop rebases. Eventually it finishes successfully.

-Peff

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Johannes Sixt]

Am 10.04.2010 06:39, schrieb Junio C Hamano:
> I used to religiously rebase slushy topics that are not in any stable
> integration branches (we used to have only 'master' and 'pu'), and
>
> 	git rebase master foo
>          git rebase master bar
>          git rebase master baz
>
> was far easier to type than
>
> 	git checkout foo&&  git rebase master
> 	git checkout bar&&  git rebase master
> 	git checkout baz&&  git rebase master

I'm actually very glad that the current interface is the way it is - 
because it can do the rebase *without* the checkout. This way you can save 
a lot of recompilation due to changed timestamps if the topic is based on 
an old version.

Only that some (all?) variants of rebase still unnecessarily do the 
checkout...

Oh, and it would naturally extend to a master..topic syntax.

-- Hannes

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Jeff King]

On Sat, Apr 10, 2010 at 09:58:54PM +0200, Johannes Sixt wrote:

> >	git checkout foo&&  git rebase master
> >	git checkout bar&&  git rebase master
> >	git checkout baz&&  git rebase master
> 
> I'm actually very glad that the current interface is the way it is -
> because it can do the rebase *without* the checkout. This way you can
> save a lot of recompilation due to changed timestamps if the topic is
> based on an old version.
> 
> Only that some (all?) variants of rebase still unnecessarily do the
> checkout...

Good point. Originally, we did the rebase directly on the branch, though
I'm not sure if we did "checkout $branch && reset $onto" or "branch -f
$branch $onto && checkout $branch". These days we operate on a detached
HEAD, and we seem to "checkout $onto^0", which should do the
optimization you mention.

-Peff

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Johannes Sixt]

On Sonntag, 11. April 2010, Jeff King wrote:
> Good point. Originally, we did the rebase directly on the branch, though
> I'm not sure if we did "checkout $branch && reset $onto" or "branch -f
> $branch $onto && checkout $branch". These days we operate on a detached
> HEAD, and we seem to "checkout $onto^0", which should do the
> optimization you mention.

But before this "checkout $onto^0" happens, some (all?) variants still 
do "checkout topic && rev-list upstream..HEAD" instead of just "rev-list 
upstream..topic".

-- Hannes

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Jeff King]

On Sun, Apr 11, 2010 at 07:54:37PM +0200, Johannes Sixt wrote:

> On Sonntag, 11. April 2010, Jeff King wrote:
> > Good point. Originally, we did the rebase directly on the branch, though
> > I'm not sure if we did "checkout $branch && reset $onto" or "branch -f
> > $branch $onto && checkout $branch". These days we operate on a detached
> > HEAD, and we seem to "checkout $onto^0", which should do the
> > optimization you mention.
> 
> But before this "checkout $onto^0" happens, some (all?) variants still 
> do "checkout topic && rev-list upstream..HEAD" instead of just "rev-list 
> upstream..topic".

I don't think this is the case any longer for regular rebase, from my
reading of the code and doing a rebase under GIT_TRACE. Grepping the
history turns up 0cb0664 (rebase [--onto O] A B: omit needless checkout,
2008-03-15).

But doing an interactive rebase under GIT_TRACE, it looks like it still
does the unnecessary checkout.

-Peff

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Michal Vitecek]

On 10.04.2010 21:58 CEST, Johannes Sixt wrote:
>Am 10.04.2010 06:39, schrieb Junio C Hamano:
>>I used to religiously rebase slushy topics that are not in any stable
>>integration branches (we used to have only 'master' and 'pu'), and
>>
>>	git rebase master foo
>>         git rebase master bar
>>         git rebase master baz
>>
>>was far easier to type than
>>
>>	git checkout foo&&  git rebase master
>>	git checkout bar&&  git rebase master
>>	git checkout baz&&  git rebase master
>
>I'm actually very glad that the current interface is the way it is -
>because it can do the rebase *without* the checkout. This way you can
>save a lot of recompilation due to changed timestamps if the topic is
>based on an old version.
>
>Only that some (all?) variants of rebase still unnecessarily do the
>checkout...

 Is there any chance for merge to behave the same? I really like that I
 don't have to do a checkout prior rebasing.

        Thanks,
-- 
		Michal Vitecek		(fuf@mageo.cz)

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Johannes Sixt]

On Montag, 12. April 2010, Michal Vitecek wrote:
>  Is there any chance for merge to behave the same? I really like that I
>  don't have to do a checkout prior rebasing.

If you mean "prior to merging", i.e., you want a "git merge --into master", 
you can do it this way:

# we are on branch 'topic' here
git checkout HEAD^0	# detach
git merge master
git reset --soft master	# keep index(!!!) and worktree
git checkout master	# re-attach
git merge topic

The point is that the second merge will succeed even with a dirty index 
because for each file the result of the merge is identical to the index!

If you have conflicts during the merge, resolve them in the first merge and 
commit to prime the rerere database; the second merge will fail for each 
conflicting file; just 'git checkout HEAD -- the/conflicting/file' and retry. 
rerere will resolve the conflicts for you.

You can of course get away with only one merge, but then you will have to do 
extra work to switch the parents around and to fix the commit message.

-- Hannes

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Eugene Sajine]

On Sat, Apr 10, 2010 at 12:26 AM, Jeff King <peff@peff.net> wrote:
> On Fri, Apr 09, 2010 at 03:35:42PM -0400, Eugene Sajine wrote:
>
>> In case of this situation
>>
>>        A  master
>>         \
>>          B  next
>>           \
>>            C  topic
>>
>>
>> $ git rebase --onto master topic
>> First, rewinding head to replay your work on top of it...
>> fatal: Not a range.
>> Nothing to do.
>>
>> Which is OK.
>
> I think this doesn't do quite what you thought. It's true there is
> "nothing to do" as in "nothing to apply", but it _did_ in fact rewind
> topic back to "master".
>
> You seem to be thinking that
>
>  git rebase --onto master topic
>
> means "rebase everything from master to topic onto master". It doesn't.
> That would be:
>
>  git rebase master topic
>
> or, if you are already on topic, just
>
>  git rebase master.
>
> The "--onto" option takes an argument, which says "put the commits on
> top of here, even though it was not the upstream base otherwise
> specified". So what your command does is say "using the current branch
> (which is topic), take everything built on top of topic (which is
> nothing), and rebuild it on top of master".

Actually no, i was not thinking about what you think i was;). What i
was trying to understand with this command (git rebase --onto master
topic) is the
behavior of the system when the topic branch is indirect descendant of
the master and the direct parent of topic (next) is omitted, skipped.

In this situatiion

git rebase master topic

does not work (see thread "git rebase command and docs questions") p1.

So, once again i think that the interface in this case worked properly:

as topic is not direct descendant, master option value goes to --onto
and there is no range defined properly.
Therefore the command worked ok, when it refused to do anything.

Now the problem i have is that:

git rebase -i --onto master topic

actually worked and did something, what i would not expect it to do.

So, the problem is: non-interactive rebase DOES NOT execute the
command, interactive DOES execute.

>
> So no, it's not a bug. Yes, it's a terrible interface. There is really
> no reason IMHO for rebase to take a "which branch to operate on"
> argument at all. It should just operate on HEAD, like merge does. If you
> want to merge on a different branch, you "git checkout" that branch
> first.

The bug is in the fact that rebase works differently in interactive
and non-interactive variants.

Thanks,
Eugene

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Jeff King]

On Sat, Apr 10, 2010 at 06:10:53PM -0400, Eugene Sajine wrote:

> Actually no, i was not thinking about what you think i was;). What i
> was trying to understand with this command (git rebase --onto master
> topic) is the behavior of the system when the topic branch is indirect
> descendant of the master and the direct parent of topic (next) is
> omitted, skipped.

But in "git rebase --onto master topic", the relationship between master
and topic is irrelevant. It is the same as:

  git rebase --onto master topic HEAD

which will consider the range between topic and HEAD as the set of
commits to rebase.

Did you want to do:

  git rebase --onto master next topic

? That would take the commits between next and topic (i.e., just "topic"
in your example), and rebuild them on top of master.

> Now the problem i have is that:
> 
> git rebase -i --onto master topic
> 
> actually worked and did something, what i would not expect it to do.
> 
> So, the problem is: non-interactive rebase DOES NOT execute the
> command, interactive DOES execute.

That's not the result I get. The non-interactive rebase _does_ do the
same thing. Try this:

  mkdir repo
  cd repo
  git init

  echo content >>file && git add file && git commit -m one
  git checkout -b next
  echo content >>file && git add file && git commit -m two
  git checkout -b topic
  echo content >>file && git add file && git commit -m three

  git rebase --onto master topic

You will see that "topic" has been reset back to commit one, the same as
master.

If that was not happening before, it was likely because you were not
actually on the "topic" branch before. So who knows what the implicit
"HEAD" argument referred to.

> The bug is in the fact that rebase works differently in interactive
> and non-interactive variants.

I don't think it does, as shown by my example above. If you still think
so, please create a short test case that demonstrates the difference.

-Peff

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Eugene Sajine]

I got your point about the HEAD which is by default get's added to the
end of the command, so it becomes

git rebase --onto master topic HEAD

I will think about it it more.

I'm pretty sure that i was surprised by the fact that i've got
different behavior in interactive and non-interactive variants, but i
will recheck.

I forgot to mention it was in windows version of git.
I will try to provide the printout of my actions tomorrow when i will
get to this machine.

Thanks a lot,
Eugene

On Sun, Apr 11, 2010 at 6:22 AM, Jeff King <peff@peff.net> wrote:
> On Sat, Apr 10, 2010 at 06:10:53PM -0400, Eugene Sajine wrote:
>
>> Actually no, i was not thinking about what you think i was;). What i
>> was trying to understand with this command (git rebase --onto master
>> topic) is the behavior of the system when the topic branch is indirect
>> descendant of the master and the direct parent of topic (next) is
>> omitted, skipped.
>
> But in "git rebase --onto master topic", the relationship between master
> and topic is irrelevant. It is the same as:
>
>  git rebase --onto master topic HEAD
>
> which will consider the range between topic and HEAD as the set of
> commits to rebase.
>
> Did you want to do:
>
>  git rebase --onto master next topic
>
> ? That would take the commits between next and topic (i.e., just "topic"
> in your example), and rebuild them on top of master.
>
>> Now the problem i have is that:
>>
>> git rebase -i --onto master topic
>>
>> actually worked and did something, what i would not expect it to do.
>>
>> So, the problem is: non-interactive rebase DOES NOT execute the
>> command, interactive DOES execute.
>
> That's not the result I get. The non-interactive rebase _does_ do the
> same thing. Try this:
>
>  mkdir repo
>  cd repo
>  git init
>
>  echo content >>file && git add file && git commit -m one
>  git checkout -b next
>  echo content >>file && git add file && git commit -m two
>  git checkout -b topic
>  echo content >>file && git add file && git commit -m three
>
>  git rebase --onto master topic
>
> You will see that "topic" has been reset back to commit one, the same as
> master.
>
> If that was not happening before, it was likely because you were not
> actually on the "topic" branch before. So who knows what the implicit
> "HEAD" argument referred to.
>
>> The bug is in the fact that rebase works differently in interactive
>> and non-interactive variants.
>
> I don't think it does, as shown by my example above. If you still think
> so, please create a short test case that demonstrates the difference.
>
> -Peff
>

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Eugene Sajine]

On Sun, Apr 11, 2010 at 10:06 AM, Eugene Sajine <euguess@gmail.com> wrote:
> I got your point about the HEAD which is by default get's added to the
> end of the command, so it becomes
>
> git rebase --onto master topic HEAD
>
> I will think about it it more.
>
> I'm pretty sure that i was surprised by the fact that i've got
> different behavior in interactive and non-interactive variants, but i
> will recheck.
>
> I forgot to mention it was in windows version of git.
> I will try to provide the printout of my actions tomorrow when i will
> get to this machine.
>
> Thanks a lot,
> Eugene


Here is the printout of my actions with some comments:

esajine@ESAJINEWWW /c/git_repos
$ mkdir test2; cd test2; git init; echo "initial" > 1.txt; git add .;
git commit -m "initial commit"; git checkout -b next; echo "commit
from next" > 2.txt; git add .; git commit -m "commit from next"; git
checkout -b topic; echo "commit from topic" > 3.txt; git add .; git
commit -m "commit from topic"
Initialized empty Git repository in c:/git_repos/test2/.git/
warning: LF will be replaced by CRLF in 1.txt
[master (root-commit) 89c5353] initial commit
warning: LF will be replaced by CRLF in 1.txt
1 files changed, 1 insertions(+), 0 deletions(-)
create mode 100644 1.txt
Switched to a new branch 'next'
warning: LF will be replaced by CRLF in 1.txt
warning: LF will be replaced by CRLF in 2.txt
[next cec1eeb] commit from next
warning: LF will be replaced by CRLF in 2.txt
1 files changed, 1 insertions(+), 0 deletions(-)
create mode 100644 2.txt
Switched to a new branch 'topic'
warning: LF will be replaced by CRLF in 1.txt
warning: LF will be replaced by CRLF in 2.txt
warning: LF will be replaced by CRLF in 3.txt
[topic 9975772] commit from topic
warning: LF will be replaced by CRLF in 3.txt
1 files changed, 1 insertions(+), 0 deletions(-)
create mode 100644 3.txt

esajine@ESAJINEWWW /c/git_repos/test2 (topic)
$ pwd
/c/git_repos/test2

esajine@ESAJINEWWW /c/git_repos/test2 (topic)
$ git status
# On branch topic
nothing to commit (working directory clean)

esajine@ESAJINEWWW /c/git_repos/test2 (topic)
$ git log
commit 9975772c641c438a0a77932c18c159e9551706ce
Author: Eugene Sajine <esajine@foo.com>
Date:   Fri Apr 9 13:04:24 2010 -0400

   commit from topic

commit cec1eebc8db042b1b8a1002b07767eac56884126
Author: Eugene Sajine <esajine@foo.com>
Date:   Fri Apr 9 13:04:24 2010 -0400

   commit from next

commit 89c5353c9b0cfc476b323db11565ea210341469a
Author: Eugene Sajine <esajine@foo.com>
Date:   Fri Apr 9 13:04:24 2010 -0400

   initial commit

esajine@ESAJINEWWW /c/git_repos/test2 (topic)
$ git rebase master
Current branch topic is up to date.
<======= Really? Topic is actually based on next – what does this "up
to date" mean??

esajine@ESAJINEWWW /c/git_repos/test2 (topic)
$ git rebase --onto master topic
First, rewinding head to replay your work on top of it...
fatal: Not a range.
Nothing to do.
                <======== topic..HEAD is not a range, agreed

esajine@ESAJINEWWW /c/git_repos/test2 (topic)
$ git rebase --onto master
fatal: Needed a single revision
invalid upstream
              <========= fine

esajine@ESAJINEWWW /c/git_repos/test2 (topic)
$ git rebase --onto master next..topic
fatal: Needed a single revision
invalid upstream next..topic
    <======== strange that this notation is not supported, considering
error above about the range

esajine@ESAJINEWWW /c/git_repos/test2 (topic)
$ git rebase -i --onto master topic
Successfully rebased and updated refs/heads/topic. <=== BUG – here it
printed me “noop” in file to edit, when I exited it should do nothing,
but it still did something and I double checked it.

esajine@ESAJINEWWW /c/git_repos/test2 (topic)
$ git rebase --onto master topic
Current branch topic is up to date.

esajine@ESAJINEWWW /c/git_repos/test2 (topic)
$ git log
commit 89c5353c9b0cfc476b323db11565ea210341469a
Author: Eugene Sajine <esajine@foo.com>
Date:   Fri Apr 9 13:04:24 2010 -0400

   initial commit
        <====== topic now points to master, last commit from topic is
lost

esajine@ESAJINEWWW /c/git_repos
$ git version
git version 1.6.4.msysgit.0

Thanks,
Eugene

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Johannes Sixt]

Am 4/12/2010 16:09, schrieb Eugene Sajine:
> esajine@ESAJINEWWW /c/git_repos/test2 (topic)
> $ git rebase master
> Current branch topic is up to date.
> <======= Really? Topic is actually based on next – what does this "up
> to date" mean??

Why should rebase bother? The difference between master and topic are
*two* commits. Since these two are already on top of master in linear
history, you get no advantage by doing a rebase operation. Therefore, you
see "already up to date".

The fact that the second commit from the tip of topic is also labeled
"next" is absolutely irrelevant to rebase. rebase only looks at the refs
that you tell it about: master and topic (implicitly pointed to by HEAD),
nothing else.

What you really want to do, obviously, is:

   git rebase --onto master next topic

No, there is no shorter form to spell this operation.

> esajine@ESAJINEWWW /c/git_repos/test2 (topic)
> $ git rebase -i --onto master topic
> Successfully rebased and updated refs/heads/topic. <=== BUG – here it
> printed me “noop” in file to edit, when I exited it should do nothing,
> but it still did something and I double checked it.

Not a bug.

Your command is the same as

   git rebase -i --onto master topic topic

because you are already on branch topic. Since there are no commits in the
range topic..topic, rebase -i told you "noop". This word is perhaps poorly
chosen, because it does not mean "no operation"[*], but "there are no
commits to transfer". But branch 'topic' that you gave as the last
argument (or implicitly by being at branch 'topic') is still transferred
--onto master. This explains the result that you observed.

Of course, if you do not 'reset --hard topic@{1}' at this point, you will
ultimately lose the commits on branch topic.

[*] You can get "no operation" by deleting the line "noop".

-- Hannes

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Eugene Sajine]

On Mon, Apr 12, 2010 at 11:13 AM, Johannes Sixt <j.sixt@viscovery.net> wrote:
> Am 4/12/2010 16:09, schrieb Eugene Sajine:
>> esajine@ESAJINEWWW /c/git_repos/test2 (topic)
>> $ git rebase master
>> Current branch topic is up to date.
>> <======= Really? Topic is actually based on next – what does this "up
>> to date" mean??
>
> Why should rebase bother? The difference between master and topic are
> *two* commits. Since these two are already on top of master in linear
> history, you get no advantage by doing a rebase operation. Therefore, you
> see "already up to date".

You lost me completely...
Rebase means change the base of the commit, change the fork point.
Current fork point for topic is next. I want it to be master. What is
up to date here???
The message is poorly worded for sure.

I know that the form i have to use is:

git rebase --onto master next topic

but it is just because topic is not direct descendant of master, isn't it?


>
>> esajine@ESAJINEWWW /c/git_repos/test2 (topic)
>> $ git rebase -i --onto master topic
>> Successfully rebased and updated refs/heads/topic. <=== BUG – here it
>> printed me “noop” in file to edit, when I exited it should do nothing,
>> but it still did something and I double checked it.
>
> Not a bug.
>
> Your command is the same as
>
>   git rebase -i --onto master topic topic
>
> because you are already on branch topic. Since there are no commits in the
> range topic..topic, rebase -i told you "noop". This word is perhaps poorly
> chosen, because it does not mean "no operation"[*], but "there are no
> commits to transfer". But branch 'topic' that you gave as the last
> argument (or implicitly by being at branch 'topic') is still transferred
> --onto master. This explains the result that you observed.
>
> Of course, if you do not 'reset --hard topic@{1}' at this point, you will
> ultimately lose the commits on branch topic.
>
> [*] You can get "no operation" by deleting the line "noop".
>
> -- Hannes
>

Come on! Please, please, explain me why it behaves DIFFERENTLY:

esajine@ESAJINEWWW /c/git_repos/test2 (topic)
$ git rebase --onto master topic
First, rewinding head to replay your work on top of it...
fatal: Not a range.
Nothing to do.
                <======== topic..HEAD is not a range, agreed


esajine@ESAJINEWWW /c/git_repos/test2 (topic)
$ git rebase -i --onto master topic
Successfully rebased and updated refs/heads/topic. <=== BUG – here it
printed me “noop” in file to edit, when I exited it should do nothing,
but it still did something and I double checked it.


Thanks,
Eugene

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Johannes Sixt]

Am 4/12/2010 17:28, schrieb Eugene Sajine:
> On Mon, Apr 12, 2010 at 11:13 AM, Johannes Sixt <j.sixt@viscovery.net> wrote:
>> Am 4/12/2010 16:09, schrieb Eugene Sajine:
>>> esajine@ESAJINEWWW /c/git_repos/test2 (topic)
>>> $ git rebase master
>>> Current branch topic is up to date.
>>> <======= Really? Topic is actually based on next – what does this "up
>>> to date" mean??
>>
>> Why should rebase bother? The difference between master and topic are
>> *two* commits. Since these two are already on top of master in linear
>> history, you get no advantage by doing a rebase operation. Therefore, you
>> see "already up to date".
> 
> You lost me completely...
> Rebase means change the base of the commit, change the fork point.

Rebase is meant to change the fork point for a history like this:

  --o--o--A--o--o--B  <-- master
           \
            o
             \
              o       <-- topic

topic forks from master at commit A; you use rebase to create history that
looks like this:

  --o--o--A--o--o--B     <-- master
                    \
                     o
                      \
                       o <-- topic

(OK, you knew that already.)

> Current fork point for topic is next. I want it to be master. What is
> up to date here???

You are already in the second situation above. The fact that you labeled
one commit "next" in between, like this:

  --o--o--A--o--o--B     <-- master
                    \
                     o   <-- next
                      \
                       o <-- topic

does not change the meaning of the command "git rebase master" in the
slightest: topic is "up to date" with respect to master.

> The message is poorly worded for sure.
> 
> I know that the form i have to use is:
> 
> git rebase --onto master next topic
> 
> but it is just because topic is not direct descendant of master, isn't it?

Watch out the wording that you use: "descendant of" has a well-defined
meaning in git, in particular, topic *is* a direct descendant of master.

What you wanted to say is: "but it is just because I have accidentally
begun to commit 'topic' on top of 'next', but I didn't want to do that".

And yes, you are right, because of this you need --onto in the rebase command.

> Come on! Please, please, explain me why it behaves DIFFERENTLY:
> 
> esajine@ESAJINEWWW /c/git_repos/test2 (topic)
> $ git rebase --onto master topic
> First, rewinding head to replay your work on top of it...
> fatal: Not a range.
> Nothing to do.
>                 <======== topic..HEAD is not a range, agreed
> 
> 
> esajine@ESAJINEWWW /c/git_repos/test2 (topic)
> $ git rebase -i --onto master topic
> Successfully rebased and updated refs/heads/topic. <=== BUG – here it
> printed me “noop” in file to edit, when I exited it should do nothing,
> but it still did something and I double checked it.

A historical accident, so to say. The implementor of interactive rebase
felt the "noop" behavior was useful, and I agree, FWIW.

-- Hannes

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Eugene Sajine]

>
>> Come on! Please, please, explain me why it behaves DIFFERENTLY:
>>
>> esajine@ESAJINEWWW /c/git_repos/test2 (topic)
>> $ git rebase --onto master topic
>> First, rewinding head to replay your work on top of it...
>> fatal: Not a range.
>> Nothing to do.
>>                 <======== topic..HEAD is not a range, agreed
>>
>>
>> esajine@ESAJINEWWW /c/git_repos/test2 (topic)
>> $ git rebase -i --onto master topic
>> Successfully rebased and updated refs/heads/topic. <=== BUG – here it
>> printed me “noop” in file to edit, when I exited it should do nothing,
>> but it still did something and I double checked it.
>
> A historical accident, so to say. The implementor of interactive rebase
> felt the "noop" behavior was useful, and I agree, FWIW.
>
> -- Hannes
>

IMHO this "noop" behavior seems to be identical to "git reset --hard
master" - the result is the same. Frankly, I don't understand what is
useful in such thing being HIDDEN in "incorrect call" of interactive
rebase...

Thanks,
Eugene

Re: [BUG] - git rebase -i performs rebase when it shouldn't?

[Johannes Sixt]

Am 4/13/2010 18:30, schrieb Eugene Sajine:
> IMHO this "noop" behavior seems to be identical to "git reset --hard
> master" - the result is the same. Frankly, I don't understand what is
> useful in such thing being HIDDEN in "incorrect call" of interactive
> rebase...

This thing is useful when you 'git rebase -i master topic' and all patches
on topic are already in master.

-- Hannes