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 > > Ciao, > Johannes > -- With best regards, Matwey V. Kornilov
