Re: Detecting redundant commits

David Greene [off-list ref] writes:

On January 4, 2016 10:00:26 PM CST, Jeff King [off-list ref] wrote:

quoted

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