From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-2.8 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI,T_RP_MATCHES_RCVD shortcircuit=no autolearn=no autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id B72B01F404 for ; Tue, 9 Jan 2018 09:50:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752696AbeAIJuO (ORCPT ); Tue, 9 Jan 2018 04:50:14 -0500 Received: from mail-ot0-f169.google.com ([74.125.82.169]:42681 "EHLO mail-ot0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752581AbeAIJuL (ORCPT ); Tue, 9 Jan 2018 04:50:11 -0500 Received: by mail-ot0-f169.google.com with SMTP id a7so710558otd.9 for ; Tue, 09 Jan 2018 01:50:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=NbanSkjpflupWMGOd9jxPTuKIKtTzYnqYEHzp09Fsp0=; b=NbRWORYBYpLv1U6+XkjVFVHu92Gybg3aYSd22l7/R6BMXQ8T29o+qKDGP12pXJbphj iOtIzoav7AVfSphSlVTdTehdiOs09Prm4CIr0Q0Dv5XBsvg+bkKWVkrKrPG0jckhNKJD qU3gNejT9Wr9MnC0oq7NkromkKoEHaFvobepcTXBv2zyWx4SZfymDNLWYe/fTEm3q2H+ 5U1wYR5F+ZYVM3BYXom7vidTuLezTFJXQt9cZqQSssgvcoGclcRQ4wdjteBzQ1JnLWcM SdI3UafDO3zfnSDRSaFCC3Nhn8ZE/hSDiKRcF5/cQjTYDPAE5uluRz19UkGdbI2DkHQb aCLQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=NbanSkjpflupWMGOd9jxPTuKIKtTzYnqYEHzp09Fsp0=; b=Fn3C10QsFkVNbX/8rgT6jqGOyh6jH0Qwlj0vYtFsy6BBTff1iRLEcEsa//himIuao1 CQyV0HiW1zbkzPERNd8GJJHbjC5YyrGrnw8+Rkfk9GRJexZea//ZpSaWgZb4nmr4wosh rkR4o1h+dENl0EsY9kN3hpz1DkyjcAXvN/afDrSNqV4S++OAUhpLzQ/IyPzaT9MKIdVQ VSEM9Gu6CT/rsZWRBBa5efipQTIJC12E1VJjfIePABazjnW5mKTugw6uISK6O0CEsOwv Y1QJNuSy6pxHPTi1JeW0lRD81N/oDbgiwf0fOFejvYWRjbkOSdYDOrWjUkXExU2mkZiE 7ckQ== X-Gm-Message-State: AKwxytcHC6RoBpS2rvdZBwGLz6RLvAfpIpUb/aD9WC029t4D3uzvux6X gJTBGdCljHXIOXyjhawn5vgbhOkCMU01FDauOmI= X-Google-Smtp-Source: ACJfBovOpq105ElKXDJPJZPI7YkW7yacMf9veF09r0Blgb0fXN4s8AfPRnty6xFNRYymlTzKvVD/+Oyk5kUVQsEmE1g= X-Received: by 10.157.6.136 with SMTP id 8mr915257otx.174.1515491410490; Tue, 09 Jan 2018 01:50:10 -0800 (PST) MIME-Version: 1.0 Received: by 10.157.73.21 with HTTP; Tue, 9 Jan 2018 01:49:50 -0800 (PST) In-Reply-To: References: From: "Matwey V. Kornilov" Date: Tue, 9 Jan 2018 12:49:50 +0300 Message-ID: Subject: Re: rebase preserve-merges: incorrect merge commits To: Johannes Schindelin Cc: git@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org 2018-01-08 22:36 GMT+03:00 Johannes Schindelin : > Hi Matwey, > > On Mon, 8 Jan 2018, Matwey V. Kornilov wrote: > >> 2018-01-08 19:32 GMT+03:00 Johannes Schindelin : >> > >> > On Mon, 8 Jan 2018, Matwey V. Kornilov wrote: >> > >> >> 2018-01-08 17:42 GMT+03:00 Matwey V. Kornilov : >> >> > 2018-01-08 16:56 GMT+03:00 Johannes Schindelin : >> >> >> 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... >> > >> >> I am sorry, didn't get it. When I do non-merge-preserving rebase >> --interactive there is no way to `pick' merge-commit at all. > > Right, but you can `pick` commits and you can get merge conflicts. And you > need to resolve those merge conflicts and those merge conflict resolutions > are not preserved for future interactive rebases, unless you use `rerere` > (in which case it also extends to `pick`ing merge commits in > merge-preserving mode). Are you talking about merge conflicts arising due to commits reordering? > > Ciao, > Johannes -- With best regards, Matwey V. Kornilov