Re: [RFC PATCH] sequencer: warn on skipping previously seen commit

From: Junio C Hamano <gitster@pobox.com>
Date: Aug 4, 2021, 21:28 UTC
Message-ID: <xmqqsfzonbm1.fsf@gitster.g>
In-Reply-To: <4d83766ab3425a5f4b361df2ac505d07fefd7899.1628109852.git.steadmon@google.com>

Josh Steadmon <steadmon@google.com> writes:

Show 11 quoted lines

> Silently skipping commits when rebasing with --no-reapply-cherry-picks
> (currently the default behavior) can cause user confusion. Issue a
> warning in this case so that users are aware of what's happening.
>
> Signed-off-by: Josh Steadmon <steadmon@google.com>
> ---
>
> We've had some complaints at $JOB where users were confused when
> rebasing branches that contained commits that were previously
> cherry-picked into their master branch. How do folks feel about adding a
> warning in this case?

I'd unconditionally in support if this were done under --verbose option, but it becomes iffy if this is done unconditionally.

This is because I do not expect everybody will stay to be ignorant of the behaviour of the tool they use every day, and I'd fear that we'd start hearing "yeah, I know the command would skip to avoid duplicated changes, why waste lines to tell me that?" complaints.

Having said that, I _hope_ that in a project with good hygiene, such a multiple cherry-picking would not be so common and an exception, and if my _hope_ proves to be true, then I am OK with giving this warning unconditionally. The user may know what the command does when it sees a duplicated change, but the warning becomes about the presence of such duplicated changes, which would be a rare event that is worth notifying about.

>  		is_empty = is_original_commit_empty(commit);
> -		if (!is_empty && (commit->object.flags & PATCHSAME))
> +		if (!is_empty && (commit->object.flags & PATCHSAME)) {
> +			warning(_("skipped previously seen commit %s"),

I am debating myself if s/seen/applied/ should be suggested here.

The existing text in the manual page says "a patch already accepted upstream with a different commit message or timestamp will be skipped", and "accepted" is a verb that would apply only in a certain workflow, which is OK in the manual page that give more context, but not here. But 'seen' feels a bit too weak to me.

> +	if (skipped_commit)
> +		warning(_("use --reapply-cherry-picks to include skipped commits"));

I'd be hesitant to endorse doing this kind of "here is how to use this command" unconditionally. Perhaps under --verbose, or hide it under "advise.*".

Thanks.