Hi, On Mon, 8 Jan 2018, Matwey V. Kornilov wrote: > 2018-01-08 17:42 GMT+03:00 Matwey V. Kornilov <matwey.kornilov@xxxxxxxxx>: > > 2018-01-08 16:56 GMT+03:00 Johannes Schindelin <Johannes.Schindelin@xxxxxx>: > >> Hi Matwey, > >> > >> On Mon, 8 Jan 2018, Matwey V. Kornilov wrote: > >> > >>> I think that rebase preserve-merges algorithm needs further > >>> improvements. Probably, you already know it. > >> > >> Yes. preserve-merges is a fundamentally flawed design. > >> > >> Please have a look here: > >> > >> https://github.com/git/git/pull/447 > >> > >> Since we are in a feature freeze in preparation for v2.16.0, I will > >> submit these patch series shortly after v2.16.0 is released. > >> > >>> As far as I understand the root cause of this that when new merge > >>> commit is created by rebase it is done simply by git merge > >>> $new_parents without taking into account any actual state of the > >>> initial merge commit. > >> > >> Indeed. preserve-merges does not allow commits to be reordered. (Actually, > >> it *does* allow it, but then fails to handle it correctly.) We even have > >> test cases that mark this as "known breakage". > >> > >> But really, I do not think it is worth trying to fix the broken design. > >> Better to go with the new recreate-merges. (I am biased, of course, > >> because I invented recreate-merges. But then, I also invented > >> preserve-merges, so ...) > > > > Well. I just checked --recreate-merges=no-rebase-cousins from the PR > > and found that it produces the same wrong result in my test example. > > The topology is reproduced correctly, but merge-commit content is > > broken. > > I did git rebase --recreate-merges=no-rebase-cousins --onto abc-0.1 v0.1 abc-0.2 > > Indeed, exactly as you still say in the documentation: "Merge conflict > resolutions or manual amendments to merge commits are not preserved." > My initial point is that they have to be preserved. Probably in > recreate-merges, if preserve-merges is discontinued. Ah, but that is consistent with how non-merge-preserving rebase works: the `pick` commands *also* do not record merge conflict resolution... Ciao, Johannes
