Re: Commited to wrong branch

From: Björn Steinbrink <b.steinbrink@gmx.de>
Date: Sep 15, 2009, 11:19 UTC
Message-ID: <20090915111922.GB31846@atjola.homenet>
In-Reply-To: <46a038f90909150355h20b39c71w4af7e2be2920fdbb@mail.gmail.com>

On 2009.09.15 12:55:58 +0200, Martin Langhoff wrote:

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> On Tue, Sep 15, 2009 at 12:31 PM, Howard Miller
> <howard@e-learndesign.co.uk> wrote:
> > I am resurrecting a discussion from a week or two back (been on
> > holiday).  As follows...
> >
> > I had made some changes to some files and then done a commit. Only
> > then did I realise that I had the wrong branch checked out. To make
> > matters worse I then did a 'git reset HEAD^' which means that I can
> > now no longer switch branches. I am stuck. I had some advice (thanks!)
> > but it was not complete. I'd appreciate some more help.
> 
> Hi Howard,
> 
> just to make sure I understand your issue
> 
>   1 - you were on branch X, thinking your were on branch Y
>   2 - edit, diff, commit, realised the mistake
>   3 - git reset HEAD^
> 
> so if you now run `git status` and `git diff` it will show your
> changes as if they were uncommitted and unstaged.

Not "as if", they are.

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> (Before you start with various attempts to recover below, a great
> trick is to make an instant-backup in case things go wrong: cd .. / ;
> cp -pr moodle.git moodle-backup.git ; cd moodle.git )
> 
> You can now try do do
> 
>   4 - git checkout Y
> 
> and if the changes are on files that don't change between X and Y,
> then git will change the branches and keep your changes there. If the
> files are different between X and Y, it won't work.

Well, then you could use "git checkout -m Y", to have git try a three-way merge (which might of course leave conflicts).

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> What I can recommend is to save your patch, as follows
> 
>   5 - git diff > tempchanges.patch
>   6 - git reset --hard # this will discard your changes, careful
>   7 - git checkout Y
>   8 - patch -p1 < tempchanges.patch
> 
> The patch may not apply cleanly :-) -- note that patch is more
> tolerant of iffy merges than git's internal implementation ("git
> apply") -- so it will succeed more often... but the results need
> review.

But a lot worse than the usual 3-way merge stuff, like "checkout -m" or "stash apply". The advantage of "stash" + "stash apply" is that, in case of conflicts, you can easily retry to fix them over and over again, while with "checkout -m", you can't easily start over AFAIK.

> There is a more git-style approach that is to use git-stash -- it uses
> git-apply and may not do what you want.

Only "stash apply --index" uses "git apply", and only to re-apply the staged changes. The changes for the working tree are applied using a 3way merge.

Björn