Re: [PATCH] Documentation: document pitfalls with 3-way merge

["brian m. carlson" <sandals@crustytoothpaste.net>]

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On Sun, Dec 08, 2013 at 02:40:13PM -0800, Jonathan Nieder wrote:
> brian m. carlson wrote:
> 
> > Oftentimes people will make the same change in two branches, revert
> > the change in one branch, and then be surprised when a merge
> > reinstitutes that change when the branches are merged.
> 
> Life is even more complicated: if the merge-base chosen happens to be
> a descendent of the change on both branches, the merge won't reinstate
> the change.

Right.  The text should probably be clearer in that respect.

> The problem scenario hasn't happened to me recently.  Can you give an
> example of how it happens?  Why is the same change being made
> independently on two different branches?  I'm wondering because such a
> story could make the example in the documentation a little clearer and
> avoid having to make the explanation overly technical.

It happens pretty much as I described.  There have been two different
posters to the list who have made the same change on both branches,
reverted it on one, and then were surprised when it was reinstated
during the merge.  Generally people expect conflicts in this case.

I don't have any further details, since it hasn't happened to me and I'm
not either one of those posters, but I suspect if someone did a
cherry-pick of a change from one branch to another that could happen.
Maybe an important bug fix was picked from a topic branch, but the
change was reverted because the problem was solved in a better way.

> In any event, that the 3-way merge is really just a stupid 3-way merge
> (modulo multiple merge base madness) does seem worth emphasizing, so
> thanks for working on this.

My goal is simply to stop having to answer the same question on the list
twice within two weeks. :-)

-- 
brian m. carlson / brian with sandals: Houston, Texas, US
+1 832 623 2791 | http://www.crustytoothpaste.net/~bmc | My opinion only
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