greened@obbligato.orgI am attempting to teach cherry-pick to handle redundant commits gracefully (via a new --skip-redundant-commits option) instead of aborting. However, I'm struggling a bit with how to check if the changes in a commit will become redundant when appied to the new HEAD.
I found diff_tree_sha1 which seems promising. Am I on the right track? If not, what's the best way to determine whether a commit object is redundant with respect to HEAD?
-David
Jeff KingRe: Detecting redundant commits
On Mon, Jan 04, 2016 at 09:59:09AM -0600, greened@obbligato.org wrote:
> I am attempting to teach cherry-pick to handle redundant commits > gracefully (via a new --skip-redundant-commits option) instead of > aborting. However, I'm struggling a bit with how to check if the > changes in a commit will become redundant when appied to the new HEAD. > > I found diff_tree_sha1 which seems promising. Am I on the right track? > If not, what's the best way to determine whether a commit object is > redundant with respect to HEAD?
Do you mean commits that are in the cherry-pick range but have matching commits already in HEAD? For that, you'd want to use patch-ids.[ch], but I think we already do.
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).
Or am I missing the point completely? :)
-Peff
David GreeneRe: Detecting redundant commits
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?
David
David A. GreeneRe: Detecting redundant commits
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