Thank you for addition. Eventually, I've merged your explanations into single
). I hope this will prevent other confused people from disturbing you by
similar emails on this mailing list.
This is another time I can evidence the power and flexibility the git provides,
thank you all for your great work!
With best regards
From: Jakub Narębski [mailto:jna...@gmail.com]
Sent: Tuesday, October 11, 2016 6:57 PM
To: Paul Smith; Eduard Egorov; 'firstname.lastname@example.org'
Subject: Re: git merge deletes my changes
W dniu 10.10.2016 o 19:52, Paul Smith pisze:
> On Mon, 2016-10-10 at 10:19 +0000, Eduard Egorov wrote:
>> # ~/gitbuild/git-2.10.1/git merge -s subtree --squash ceph_ansible
>> Can somebody confirm this please? Doesn't "merge -s subtree" really
>> merges branches?
> I think possibly you're not fully understanding what the --squash flag
> does... that's what's causing your issue here, not the "-s" option.
> A squash merge takes the commits that would be merged from the origin
> branch and squashes them into a single patch and applies them to the
> current branch as a new commit... but this new commit is not a merge
> commit (that is, when you look at it with "git show" etc. the commit
> will have only one parent, not two--or more--parents like a normal
> merge commit).
> Basically, it's syntactic sugar for a diff plus patch operation plus
> some Git goodness wrapped around it to make it easier to use.
Actually this is full merge + commit surgery (as if you did merge with
--no-commit, then deleted MERGE_HEAD); the state of worktree is as if it were
after a merge.
> But ultimately once you're done, Git has no idea that this new commit
> has any relationship whatsoever to the origin branch. So the next
> time you merge, Git doesn't know that there was a previous merge and
> it will try to merge everything from scratch rather than starting at
> the previous common merge point.
> So either you'll have to use a normal, non-squash merge, or else
> you'll have to tell Git by hand what the previous common merge point
> was (as Jeff King's excellent email suggests). Or else, you'll have
> to live with this behavior.
The `git subtree` command (from contrib) allows yet another way: it squashes
*history* of merged subproject (as if with interactive rebase 'squash'), then
merges this squash commit.
Now I know why this feature is here...