From: David A. Greene <greened@obbligato.org>
Date: Fri, 08 Jan 2016 03:14:22 GMT
Subject: Re: Detecting redundant commits
Message-ID: <87d1tcyd81.fsf@waller.obbligato.org>
In-Reply-To: <49661552-EBD9-4F45-9F31-54B217AE3350@obbligato.org>

David Greene <greened@obbligato.org> writes:

> On January 4, 2016 10:00:26 PM CST, Jeff King <peff@peff.net> wrote:
>
>>Or do you mean commits that, when applied, we find turn out to have
>>empty changes (e.g., because we have a set of commits that have
>>different patch-ids, but do roughly the same thing)? I don't think you
>>can find that with a straight end-to-end diff. You have try to apply
>>and then look at the result. I think we already catch that case (see
>>--allow-empty), though I think the only options are "preserve" or
>>"abort", not "silently skip" (and it sounds like the latter is what
>>you would want).
>
> This.  I see where --allow-empty is handled in prepare_to_commit but
> it is not so easy to skip the commit at that point due to state
> changes.  I was trying to avoid going into commit at all by
> determining ahead of time whether the commit would become empty.  Any
> ideas?

I ended up trying index_differs_from("HEAD", 0) and that actually seems
to work.  Unfortunately, it caused a regression and I'm having trouble
figuring out why.  The code should not even activate without a new
option specified.  If I get it working I'll send a patchset for comment.
Point me another direction if I'm way off track.  :)

                       -David