Re: [RFC PATCH 0/1] rebase --onto detection of already applied commits

[Cristian Ciocaltea <cristian.ciocaltea@collabora.com>]

Hi Phillip,

On 12/15/22 17:40, Phillip Wood wrote:
> Hi Cristian
> 
> On 13/12/2022 15:34, Cristian Ciocaltea wrote:
>> Hi Phillip,
>>
>> On 12/13/22 15:04, Phillip Wood wrote:
>>> Hi Christian
>>>
>>> On 13/12/2022 10:37, Cristian Ciocaltea wrote:
>>>> Currently '--onto' works as if the user provided the 
>>>> '--reapply-cherry-picks' flag,
>>>
>>> --onto does not affect the cherry-pick detection. When running
>>>
>>>      git rebase --onto new-base upstream feature
>>>
>>> any commits in upstream have been cherry-picked from feature they 
>>> will not be rebased. What it does not do is look for cherry-picks in 
>>> onto...feature. It would be nice to add that but I'm not sure it is 
>>> straight forward to do so and still exclude commits that have been 
>>> cherry-picked from feature to upstream.
>>
>> The proposed patch enables looking for commits into new-base..feature 
>> range and excluding the ones reachable from upstream. Since this is a 
>> change in the existing behavior, we might need to introduce a new flag 
>> to enable it. I previously suggested to use 
>> '--no-reapply-cherry-picks' for this purpose, but now it's pretty 
>> obvious this will be a source of confusion, since the "cherry-picks" 
>> term refers to the commits picked from feature to upstream instead of 
>> new-base, as you already mentioned.
>>
>> I agree it would be nice to support both exclusion ranges, but I'm not 
>> sure how complicated the implementation would be, since I don't have 
>> any previous experience with the Git internals. Could this be added as 
>> a separate feature at a later point?
> 
> If we can I'd rather add code that excludes cherry-pick both ranges. To 
> remove the cherry-picks that are in upstream and new-base you could 
> rework the todo list generation as follows
> 
> 1. Calculate the merge-base $mb of feature and upstream
> 2. Store the list of commits $mb..feature in an array and in a hash
>     table indexed their patch-id.
> 3. Walk $mb..upstream calculating the patch-id for each commit and
>     removing any commit in the list from step 2 that matches.
> 4. If onto is equal to upstream skip to step 7
> 5. Calculate the merge-base $mb of feature and onto.
> 6. Walk $mb..new-base calculating the patch-id for each commit and
>     removing any commit in the list from step 2 that matches.
> 7. Generate the todo list using the modified list of commits from step
>     2.
> 
> I don't have much time at the moment but I can try and help a bit more 
> in the New Year if you want.

Thank you for the implementation hints and your availability to help 
further! I will try to put this in practice and let you know as soon as 
I get something working.

Kind regards,
Cristian

> Best Wishes
> 
> Phillip