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

From: Junio C Hamano <[email-masked]>
Date: Wed, 04 Aug 2021 14:28:22 -0700

Josh Steadmon <[email-masked]> writes:

> 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 <[email-masked]>
> ---
>
> 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.