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

[Phillip Wood <phillip.wood123@gmail.com>]

On 15/12/2022 16:02, Cristian Ciocaltea wrote:
> 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.

I'd start by looking at the existing todo list generation in 
sequencer.c:sequencer_make_script()

Best Wishes

Phillip