From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.1 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id DD8E31F453 for ; Thu, 21 Feb 2019 21:41:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726694AbfBUVlO (ORCPT ); Thu, 21 Feb 2019 16:41:14 -0500 Received: from mail-wr1-f52.google.com ([209.85.221.52]:39925 "EHLO mail-wr1-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726541AbfBUVlN (ORCPT ); Thu, 21 Feb 2019 16:41:13 -0500 Received: by mail-wr1-f52.google.com with SMTP id l5so116199wrw.6 for ; Thu, 21 Feb 2019 13:41:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=Hh961CJQ1uFECSxOyL9rl5Fqv1o8hWa3t6aeioUOcmo=; b=Ss3HMXAnkqMQTr4Ie+72L6LU2rkZRDYQDgAoLKMGxmRksx7InQqW4Cpx93uZjLV4Oj 1y7PAA3yvaAFA+dR5AeQepEVjIP9jtoebPWN4y5gfbTiW9pOHetPx9QgY0TIR4oYg4sI alLiHf5/hhkaSjo2kfl3hz6gk3yf3RMB2xtApYzpc+1c3v0CZDpNHy20ipo3PY6ajtjQ cP4YO+htU+f5eN/YboaZfl0zyXAPmpOkU6nF5lxRP30rgc78oLNXJHqqjWDvvsm9fkYM rCTyH6IKnp8tZh3ZzasiGk8xvsCK0yozR4lKqRq0CvDRuiOgNmCAlDxuqg5lUjjj5T7u vb7A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=Hh961CJQ1uFECSxOyL9rl5Fqv1o8hWa3t6aeioUOcmo=; b=Qr4r/3zz58ngbbujvh6AdGqse6KMHaCP7KrggjSXn43TkRVE2vHJLlktZ3TSBDzJMA Ja1ynOZz6e0Ay8jsWWIXD8NyHeEGwVuE0N4vzSUjK4lVZwmRWWITuFAfauJ6qjFO6wAA g1zfgLZ4wAFNZ8CCOtukJa7VUmHo+CQXfPNg+jwjNhx9AuAROs822bvsGWKY0UO57zK5 DlBLN3hwmCm2BPZJn8DNoZDmDha3H8zgZQHgD2Q04+a6xlYW7dVU3HupP+VM45QtVQpI vw2rSoMEtmmJKLZ/xllcbA7RuE+uJ0P5CytTtWW8TazkRTeisYt02tFrsiQEDPT86EAj v/9A== X-Gm-Message-State: AHQUAuYsP0bRaO2Wb0zarYSAm4TeEC40a2plwpRTIG2D2u7ApyyoPpcy tZUIA19J0syLaOubFf5O/edlR3CxeeE= X-Google-Smtp-Source: AHgI3IYm6gbe1zr2YpwMSM6XYPkYhikGN2eNb0U1wusHH/2HcoZNI9p3BtI3CmyG0OVECj1d1WCaFA== X-Received: by 2002:a5d:4e8c:: with SMTP id e12mr401865wru.21.1550785271040; Thu, 21 Feb 2019 13:41:11 -0800 (PST) Received: from vm.nix.is ([2a01:4f8:120:2468::2]) by smtp.gmail.com with ESMTPSA id k6sm17536972wrq.82.2019.02.21.13.41.10 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Thu, 21 Feb 2019 13:41:10 -0800 (PST) From: =?UTF-8?q?=C3=86var=20Arnfj=C3=B6r=C3=B0=20Bjarmason?= To: git@vger.kernel.org Cc: Junio C Hamano , Jeff King , Johannes Schindelin , Johannes Sixt , John Keeping , Pratik Karki , =?UTF-8?q?=C3=86var=20Arnfj=C3=B6r=C3=B0=20Bjarmason?= Subject: [PATCH 2/2] rebase: don't rebase linear topology with --fork-point Date: Thu, 21 Feb 2019 22:40:59 +0100 Message-Id: <20190221214059.9195-3-avarab@gmail.com> X-Mailer: git-send-email 2.21.0.rc0.258.g878e2cd30e In-Reply-To: <20190221151009.GA24309@sigill.intra.peff.net> References: <20190221151009.GA24309@sigill.intra.peff.net> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Fix a regression introduced in 4f21454b55 ("merge-base: handle --fork-point without reflog", 2016-10-12). Before that change having a linear history on top of an upstream master would with --fork-point (aka argument-less rebase) tell us there was nothing to be done: $ git rebase Current branch master is up to date. After that change "rebase" will always redundantly find that it has work to do (it doesn't): $ git rebase First, rewinding head to replay your work on top of it... Applying: [...] Whereas equivalently running: $ git rebase @{upstream} $ git rebase $(git merge-base --fork-point @{u}) Gives us the old behavior of doing nothing. Now, why did we have this regression? Fully digging into it yields an interesting combination of causes: Way back in 1308c17b3e ("Allow rebase to run if upstream is completely merged", 2007-07-04) "rebase" learned to not do this redundant work when asked to rebase on a commit that was already an ancestor of the current commit. Then in 1e0dacdbdb ("rebase: omit patch-identical commits with --fork-point", 2014-07-16) a rebase bug was fixed for a case where the history to be rebased was divergent by entirely skipping the 2007-era logic if --fork-point was provided. But here's the critical thing, *only* if the --fork-point was divergent. At that time "git merge-base --fork-point A B" would return nothing if the two commits weren't divergent. Then in 4f21454b55 ("merge-base: handle --fork-point without reflog", 2016-10-12) which introduced the regression being fixed here, a bug fix for "git merge-base --fork-point" being run stand-alone by proxy broke this use-case git-rebase.sh was relying on, since it was still assuming that if we didn't have divergent history we'd have no output. Finally, when "rebase" was rewritten in C a combination of 9a48a615b4 ("builtin rebase: try to fast forward when possible", 2018-09-04), 103148aad8 ("merge-base --fork-point: extract libified function", 2018-09-04) and 92d0d74e8d ("builtin rebase: support `fork-point` option", 2018-09-04) faithfully re-implemented the then-buggy behavior. So let's fix this. It's easy enough, we just stop explicitly excluding --fork-point from the can_fast_forward(...) test we're doing, which as discussed above is faithfully ported over from buggy shellscript-era logic. I'm not bothering to fix this in the legacy rebase mode. As discussed in 9aea5e9286 ("rebase: fix regression in rebase.useBuiltin=false test mode", 2019-02-13) it'll be going away shortly after 2.21.0 lands. Signed-off-by: Ævar Arnfjörð Bjarmason --- builtin/rebase.c | 6 ++++-- t/t3421-rebase-topology-linear.sh | 15 +++++++++++++++ 2 files changed, 19 insertions(+), 2 deletions(-) diff --git a/builtin/rebase.c b/builtin/rebase.c index 7c7bc13e91..7a16b8051c 100644 --- a/builtin/rebase.c +++ b/builtin/rebase.c @@ -1664,9 +1664,11 @@ int cmd_rebase(int argc, const char **argv, const char *prefix) * and if this is not an interactive rebase. */ if (can_fast_forward(options.onto, &options.orig_head, &merge_base) && - !is_interactive(&options) && !options.restrict_revision && + !is_interactive(&options) && options.upstream && - !oidcmp(&options.upstream->object.oid, &options.onto->object.oid)) { + (options.restrict_revision + ? !oidcmp(&options.upstream->object.oid, &options.restrict_revision->object.oid) + : !oidcmp(&options.upstream->object.oid, &options.onto->object.oid))) { int flag; if (!(options.flags & REBASE_FORCE)) { diff --git a/t/t3421-rebase-topology-linear.sh b/t/t3421-rebase-topology-linear.sh index b847064f91..1754537789 100755 --- a/t/t3421-rebase-topology-linear.sh +++ b/t/t3421-rebase-topology-linear.sh @@ -55,6 +55,21 @@ test_run_rebase success -m test_run_rebase success -i test_have_prereq !REBASE_P || test_run_rebase success -p +test_run_rebase () { + result=$1 + shift + test_expect_$result "rebase $* is no-op if remote upstream is an ancestor" " + reset_rebase && + GIT_TEST_REBASE_USE_BUILTIN=true git rebase $* branch-b branch-e && + test_cmp_rev e HEAD + " +} +test_run_rebase success '' +test_run_rebase success --fork-point +test_run_rebase success -m +test_run_rebase success -i +test_have_prereq !REBASE_P || test_run_rebase success -p + test_run_rebase () { result=$1 shift -- 2.21.0.rc0.258.g878e2cd30e