git@vger.kernel.org list mirror (unofficial, one of many)
 help / color / mirror / code / Atom feed
From: Elijah Newren <newren@gmail.com>
To: git@vger.kernel.org
Cc: gitster@pobox.com, corrmage@gmail.com, avarab@gmail.com,
	Johannes.Schindelin@gmx.de, sbeller@google.com,
	Elijah Newren <newren@gmail.com>
Subject: [PATCH 3/3] am: avoid directory rename detection when calling recursive merge machinery
Date: Wed, 29 Aug 2018 00:06:13 -0700	[thread overview]
Message-ID: <20180829070613.11793-4-newren@gmail.com> (raw)
In-Reply-To: <20180829070613.11793-1-newren@gmail.com>

Let's say you have the following three trees, where Base is from one commit
behind either master or branch:

   Base  : bar_v1, foo/{file1, file2, file3}
   branch: bar_v2, foo/{file1, file2},       goo/file3
   master: bar_v3, foo/{file1, file2, file3}

Using git-am (or am-based rebase) to apply the changes from branch onto
master results in the following tree:

   Result: bar_merged, goo/{file1, file2, file3}

This is not what users want; they did not rename foo/ -> goo/, they only
renamed one file within that directory.  The reason this happens is am
constructs fake trees (via build_fake_ancestor()) of the following form:

   Base_bfa  : bar_v1, foo/file3
   branch_bfa: bar_v2, goo/file3

Combining these two trees with master's tree:

   master: bar_v3, foo/{file1, file2, file3},

You can see that merge_recursive_generic() would see branch_bfa as renaming
foo/ -> goo/, and master as just adding both foo/file1 and foo/file2.  As
such, it ends up with goo/{file1, file2, file3}

The core problem is that am does not have access to the original trees; it
can only construct trees using the blobs involved in the patch.  As such,
it is not safe to perform directory rename detection within am -3.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 builtin/am.c                    | 1 +
 t/t3401-rebase-and-am-rename.sh | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/builtin/am.c b/builtin/am.c
index 2fc2d1e82c..1494a9be84 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -1596,6 +1596,7 @@ static int fall_back_threeway(const struct am_state *state, const char *index_pa
 	o.branch1 = "HEAD";
 	their_tree_name = xstrfmt("%.*s", linelen(state->msg), state->msg);
 	o.branch2 = their_tree_name;
+	o.detect_directory_renames = 0;
 
 	if (state->quiet)
 		o.verbosity = 0;
diff --git a/t/t3401-rebase-and-am-rename.sh b/t/t3401-rebase-and-am-rename.sh
index a87df9e675..94bdfbd69c 100755
--- a/t/t3401-rebase-and-am-rename.sh
+++ b/t/t3401-rebase-and-am-rename.sh
@@ -152,7 +152,7 @@ test_expect_success 'rebase --interactive: NO directory rename' '
 	)
 '
 
-test_expect_failure 'rebase (am): NO directory rename' '
+test_expect_success 'rebase (am): NO directory rename' '
 	test_when_finished "git -C no-dir-rename rebase --abort" &&
 	(
 		cd no-dir-rename &&
@@ -190,7 +190,7 @@ test_expect_success 'rebase --merge: NO directory rename' '
 	)
 '
 
-test_expect_failure 'am: NO directory rename' '
+test_expect_success 'am: NO directory rename' '
 	test_when_finished "git -C no-dir-rename am --abort" &&
 	(
 		cd no-dir-rename &&
-- 
2.18.0.12.g97a29da30a


  parent reply	other threads:[~2018-08-29  7:06 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-28 12:27 A rebase regression in Git 2.18.0 Nikolay Kasyanov
2018-08-28 13:17 ` Ævar Arnfjörð Bjarmason
2018-08-28 13:33   ` Johannes Schindelin
2018-08-28 13:46     ` Nikolay Kasyanov
2018-08-28 15:35     ` Elijah Newren
2018-08-28 16:58       ` Junio C Hamano
2018-08-29  7:06         ` [PATCH 0/3] Turn off directory rename detection in am -3 Elijah Newren
2018-08-29  7:06           ` [PATCH 1/3] t3401: add another directory rename testcase for rebase and am Elijah Newren
2018-08-29 22:12             ` Junio C Hamano
2018-08-29 23:47               ` Elijah Newren
2018-08-30 16:01                 ` Junio C Hamano
2018-08-30 16:26                   ` Elijah Newren
2018-08-29  7:06           ` [PATCH 2/3] merge-recursive: add ability to turn off directory rename detection Elijah Newren
2018-08-29 12:54             ` Johannes Schindelin
2018-08-29 23:00               ` Elijah Newren
2018-08-29  7:06           ` Elijah Newren [this message]
2018-08-29 12:51             ` [PATCH 3/3] am: avoid directory rename detection when calling recursive merge machinery Johannes Schindelin
2018-08-30 16:41         ` A rebase regression in Git 2.18.0 Elijah Newren
2018-08-31 10:11           ` Johannes Schindelin
2018-08-31 19:37             ` Elijah Newren

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: http://vger.kernel.org/majordomo-info.html

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180829070613.11793-4-newren@gmail.com \
    --to=newren@gmail.com \
    --cc=Johannes.Schindelin@gmx.de \
    --cc=avarab@gmail.com \
    --cc=corrmage@gmail.com \
    --cc=git@vger.kernel.org \
    --cc=gitster@pobox.com \
    --cc=sbeller@google.com \
    --subject='Re: [PATCH 3/3] am: avoid directory rename detection when calling recursive merge machinery' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

git@vger.kernel.org list mirror (unofficial, one of many)

This inbox may be cloned and mirrored by anyone:

	git clone --mirror https://public-inbox.org/git
	git clone --mirror http://ou63pmih66umazou.onion/git
	git clone --mirror http://czquwvybam4bgbro.onion/git
	git clone --mirror http://hjrcffqmbrq6wope.onion/git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V1 git git/ https://public-inbox.org/git \
		git@vger.kernel.org
	public-inbox-index git

Example config snippet for mirrors.
Newsgroups are available over NNTP:
	nntp://news.public-inbox.org/inbox.comp.version-control.git
	nntp://7fh6tueqddpjyxjmgtdiueylzoqt6pt7hec3pukyptlmohoowvhde4yd.onion/inbox.comp.version-control.git
	nntp://ie5yzdi7fg72h7s4sdcztq5evakq23rdt33mfyfcddc5u3ndnw24ogqd.onion/inbox.comp.version-control.git
	nntp://4uok3hntl7oi7b4uf4rtfwefqeexfzil2w6kgk2jn5z2f764irre7byd.onion/inbox.comp.version-control.git
	nntp://news.gmane.io/gmane.comp.version-control.git
 note: .onion URLs require Tor: https://www.torproject.org/

code repositories for project(s) associated with this inbox:

	https://80x24.org/mirrors/git.git

AGPL code for this site: git clone https://public-inbox.org/public-inbox.git