Re: Rebasing a branch with merges
From: "Robert Dailey" <rcdailey.lists@gmail.com>
Show 35 quoted lines
> On Fri, Jan 6, 2017 at 3:28 PM, Philip Oakley <philipoakley@iee.org>
> wrote:
>> From: "Robert Dailey" <rcdailey.lists@gmail.com>
>>>
>>> Here's the scenario:
>>>
>>> I create a topic branch so one other developer and myself can work on
>>> a feature that takes 2 weeks to complete. During that 2 week period,
>>> changes are occurring on master that I need in my topic branch. Since
>>> I have a collaborator on the branch, I opt for merges instead of
>>> rebase.
>>>
>>> Each day I merge from master to the topic branch, which changes code
>>> I'm actively working in and requires semantic changes (functions
>>> renamed, moved, etc).
>>>
>>> Once I'm ready to merge the topic branch back into master, I have two
>>> options (bearing in mind the goal is to keep history as clean as
>>> possible. Furthermore this implies that the constant merging into
>>> topic from master has made the topic branch look unwieldy and
>>> difficult to audit):
>>
>>
>> a broader question zero;
>> 0. Is the merge always clean? Do you always do a preparatory fixup! to
>> ensure that the merge will be clean?
>>
>> Ensuring that the merge will be clean should greatly simplify your
>> decision
>> about process.
>
> I don't understand what you're asking. How would I do a fixup with
> merges? Can you explain a bit? Normally the only time I use fixup! or
> squash! is for local changes prior to pushing.
>
I was using 'fixup!' figuratively, rather than literally. If I understand the general setup correctly, what you want is that if one does a trial merge, then it must merge cleanly, compile and pass all tests, or if it doesn't, you would need to add that extra commit to ensure that you get that clean merge.
The alternative is that there is extra work to be done after the 'merge' (which may be a management choice) to then get your nice code ready for wider release - it may even be someone elses job to do 'integration'.
Either way, at least if you rationalise the clean end point it becomes easier to discuss the start point. If both ends are 'dirty' it is an open argument...
Show 22 quoted lines
>>> 1. Do a squash merge, which keeps history clean but we lose context
>>> for the important bits (the commits representing units of work that
>>> contribute to the topic itself).
>>>
>>> 2. Do a final rebase prior to merging.
>>>
>>> #2 doesn't seem to be possible due to patch ordering. For example, if
>>> I have real commits after merge commits that depend on those changes
>>> from master being present as a base at that point in time, the rebase
>>> will cause the patch before it to no longer include those changes from
>>> master.
>>
>>
>> How much of the historic fixups to cover changes on master do you want to
>> keep visible? i.e. how many fork-points are truly needed (a. by you, b.
>> by
>> the project - personal knowledge vs corporate knowledge).?
>
>
> Again, I do not understand. Maybe the first question you asked needs
> to be understood before I can answer this one. Sorry for the trouble.
>
In some scenarios it is important to keep the record of the exact start point (date and place) to formally justify the work performed (time eleapsed etc). Now given the other part of your scenario of a moving api / function naming etc, you now have two reference points - the original start point, and the release point of the new api/names.
So at that point you probably want to merge in those changes (one way or another), which gives you a choice of a true merge (option 1), or adding a patch to cherry pick the bulk changes on master (option2), or just the api changes (if you can isolate them) (option3). No option is inherently better - it will depend on local needs.
From a clean code perspective, it's nicest if you can simply rebase your code, but that isn't alway possible. The hard bit is to be clear about the local issues, and which ones are immutable. These will decide your choice.
Philip
