Re: Question about merge & cherry pick

From: Johannes Sixt <j6t@kdbg.org>
Date: Nov 7, 2024, 17:18 UTC
Message-ID: <eb3a25c0-7f43-4811-a9ad-0388f395b26e@kdbg.org>
In-Reply-To: <a129e967-efba-48ba-b5a0-1abbb0af5c9d@maurel.me>

Am 07.11.24 um 11:32 schrieb Julien Maurel:

Show 9 quoted lines

> Le 07/11/2024 à 07:37, Johannes Sixt a écrit :
>> A merge does not consider the individual changes on the branches, but
>> only the differences since the merge base. For the merge operation, the
>> change from Z to Y never happened on the dev side. The reversal of Y to
>> Z is not visible for the merge and cannot contribute to the result.
> 
> Ok, I didn't have this vision about how merge is apply, thanks.
> There is no option to merge by considering each commit individually ?
> Rebase do it but not applicable in my case :)

You can merge the dev branch in two steps:

          A Z Q E        initial commit
          /      \
      A Y Q E     |      dev: Z -> Y
         |\       |
         | \   A Y Q E   master: cherry-pick Z -> Y
         |  \     |
         |   A Y Q E     master: merge dev
         |        |
      A Z Q D     |      dev: revert Y -> Z and change E -> D
          \      /
          A Z Q D        merge again

The merge of dev into master changes the merge base of the final merge: it is the second commit in the diagram. Now there is no contribution to the merge from the master branch anymore, because its tip is identical to the merge base, and both changes made in the second commit on dev are visible and contribute to the merge result.

-- Hannes