14.10.2020, 01:30, "Ryosuke Niwa" <rn...@webkit.org>:
> On Tue, Oct 13, 2020 at 2:37 PM Konstantin Tokarev <annu...@yandex.ru> wrote:
>> 13.10.2020, 22:33, "Maciej Stachowiak" <m...@apple.com>:
>> >> On Oct 2, 2020, at 10:59 AM, Michael Catanzaro <mcatanz...@gnome.org>
>> wrote:
>> >>
>> >> On Fri, Oct 2, 2020 at 6:36 pm, Philippe Normand <ph...@igalia.com>
>> wrote:
>> >>> Would you also consider preventing merge commits in order to keep a
>> >>> clean mainline branch?
>> >>
>> >> Big +1 to blocking merge commits. Merge commits in a huge project like
>> WebKit would make commit archaeology very frustrating. (I assume this is
>> implied by the monotonic commit identifiers proposal, but it doesn't exactly
>> say that.)
>> >
>> > I’m assuming your objection is to regular merges, but how do you feel
>> about squash merges? Or do you think all PRs should be landed by rebasing?
>>
>> I'm not Michael but will add my 2 dollars anyway :)
>>
>> In these two approaches commits inside PR have different meaning, and
>> workflow is different.
>>
>> Below I use a term "atomic change" to describe minimal code change which is
>> a self-contained work unit with following properties:
>> * It implements well-defined task which can be summarized as a short
>> English sentence (typical soft limit is 60 characters)
>> * It doesn't introduce defects (e.g. bugs, compilation breakages, style
>> errors, typos) which were discovered during review process
>> * It doesn't include any code changes unrelated to main topic. This
>> separation is sometimes subjective, but it's usually recommended to split
>> refactoring and implementation of feature based on that, bug fix and new
>> feature, big style change and fix or feature.
>>
>> AFAIU our current review process has similar requirements to patches
>> submitted to Bugzilla, though sometimes patches include unrelated changes.
>> This can be justified by weakness of webkit-patch/Bugzilla tooling which has
>> no support for patch series, and by fact that SVN doesn't support keeping
>> local patch series at all.
>>
>> 1. Workflow 1 - "Squash merge" policy
>>
>> * Whole PR is considered to be a single atomic change of WebKit source
>> tree. If work is supposed to be landed as a series of changes which depend
>> on each other (e.g. refactoring and feature based on it, or individual
>> separate features touching same parts of code), each change needs a separate
>> PR, and, as a consequence, only one of them can be efficiently reviewed at
>> the moment of time
>> * Commits in PR represent review iterations or intermediate implementation
>> progress
>> * Reviewers' comments are addressed by pushing new commits without
>> rewriting history, which works around GitHub's lack of "commit revisions".
>> Also this workflow has lower entry barrier for people who haven't mastered
>> git yet, as it requires only "git commit" and "git push" without rebases.
>>
>> 2. Workflow 2 - "Rebase" ("cherry-pick")) or "Merge" policy
>>
>> * PR is considered to be a series of atomic changes. If work consists of
>> several atomic changes, each commit represent an atomic change
>> * Review iterations are done by fixing commits in place and reuploading
>> entire series using force push (of course if review discovers that
>> substantial part of work is missing it can be added as a new atomic commit
>> to the series)
>> * It's possible to review each commit in the series separately
>> * Workflow requires developers to have more discipline and experience with
>> using git rebase for history rewriting. Entry barrier can be lowered by
>> providing step by step instructions like e.g. [1].
>
> I really dislike this workflow due to its inherent complexity. Having
> to use Git is enough of a burden already. I don't want to deal with an
> extra layer of complexity to deal with.
There is simplified version of workflow 2 when you have only one commit in PR.
In this case you can easily edit this single commit with gic commit --amend or
GUI tools to address review comments. At the same time those who are more
comfortable with git can use longer patch series.
--
Regards,
Konstantin
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