From: Elijah Newren <newren@gmail.com>
To: git@vger.kernel.org
Cc: Junio C Hamano <gitster@pobox.com>,
Johannes Schindelin <Johannes.Schindelin@gmx.de>,
Elijah Newren <newren@gmail.com>
Subject: [PATCH v2 03/20] Ensure index matches head before invoking merge machinery, round N
Date: Fri, 26 Jul 2019 08:52:41 -0700 [thread overview]
Message-ID: <20190726155258.28561-4-newren@gmail.com> (raw)
In-Reply-To: <20190726155258.28561-1-newren@gmail.com>
This is the bug that just won't die; there always seems to be another
form of it somewhere. See the commit message of 55f39cf7551b ("merge:
fix misleading pre-merge check documentation", 2018-06-30) for a more
detailed explanation), but in short:
<quick summary>
builtin/merge.c contains this important requirement for merge
strategies:
...the index must be in sync with the head commit. The strategies are
responsible to ensure this.
This condition is important to enforce because there are two likely
failure cases when the index isn't in sync with the head commit:
* we silently throw away changes the user had staged before the merge
* we accidentally (and silently) include changes in the merge that
were not part of either of the branches/trees being merged
Discarding users' work and mis-merging are both bad outcomes, especially
when done silently, so naturally this rule was stated sternly -- but,
unfortunately totally ignored in practice unless and until actual bugs
were found. But, fear not: the bugs from this were fixed in commit
ee6566e8d70d ("[PATCH] Rewrite read-tree", 2005-09-05)
through a rewrite of read-tree (again, commit 55f39cf7551b has a more
detailed explanation of how this affected merge). And it was fixed
again in commit
160252f81626 ("git-merge-ours: make sure our index matches HEAD", 2005-11-03)
...and it was fixed again in commit
3ec62ad9ffba ("merge-octopus: abort if index does not match HEAD", 2016-04-09)
...and again in commit
65170c07d466 ("merge-recursive: avoid incorporating uncommitted changes in a merge", 2017-12-21)
...and again in commit
eddd1a411d93 ("merge-recursive: enforce rule that index matches head before merging", 2018-06-30)
...with multiple testcases added to the testsuite that could be
enumerated in even more commits.
Then, finally, in a patch in the same series as the last fix above, the
documentation about this requirement was fixed in commit 55f39cf7551b
("merge: fix misleading pre-merge check documentation", 2018-06-30), and
we all lived happily ever after...
</quick summary>
Unfortunately, "ever after" apparently denotes a limited time and it
expired today. The merge-recursive rule to enforce that index matches
head was at the beginning of merge_trees() and would only trigger when
opt->call_depth was 0. Since merge_recursive() doesn't call
merge_trees() until after returning from recursing, this meant that the
check wasn't triggered by merge_recursive() until it had first finished
all the intermediate merges to create virtual merge bases. That is a
potentially HUGE amount of computation (and writing of intermediate
merge results into the .git/objects directory) before it errors out and
says, in effect, "Sorry, I can't do any merging because you have some
local changes that would be overwritten."
Trying to enforce that all of merge_trees(), merge_recursive(), and
merge_recursive_generic() checked the index == head condition earlier
resulted in a bunch of broken tests. It turns out that
merge_recursive() has code to drop and reload the cache while recursing
to create intermediate virtual merge bases, but unfortunately that code
runs even when no recursion is necessary. This unconditional dropping
and reloading of the cache masked a few bugs:
* builtin/merge-recursive.c: didn't even bother loading the index.
* builtin/stash.c: feels like a fake 'builtin' because it repeatedly
invokes git subprocesses all over the place, mixed with other
operations. In particular, invoking "git reset" will reset the
index on disk, but the parent process that invoked it won't
automatically have its in-memory index updated.
* t3030-merge-recursive.h: this test has always been broken in that it
didn't make sure to make index match head before running. But, it
didn't care about the index or even the merge result, just the
verbose output while running. While commit eddd1a411d93
("merge-recursive: enforce rule that index matches head before
merging", 2018-06-30) should have uncovered this broken test, it
used a test_must_fail wrapper around the merge-recursive call
because it was known that the merge resulted in a rename/rename
conflict. Thus, that fix only made this test fail for a different
reason, and since the index == head check didn't happen until after
coming all the way back out of the recursion, the testcase had
enough information to pass the one check that it did perform.
So, load the index in builtin/merge-recursive.c, reload the in-memory
index in builtin/stash.c, and modify the t3030 testcase to correctly
setup the index and make sure that the test fails in the expected way
(meaning it reports a rename/rename conflict).
Signed-off-by: Elijah Newren <newren@gmail.com>
---
builtin/merge-recursive.c | 4 ++++
builtin/stash.c | 2 ++
t/t3030-merge-recursive.sh | 9 ++++++++-
3 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/builtin/merge-recursive.c b/builtin/merge-recursive.c
index 5b910e351e..a4bfd8fc51 100644
--- a/builtin/merge-recursive.c
+++ b/builtin/merge-recursive.c
@@ -1,3 +1,4 @@
+#include "cache.h"
#include "builtin.h"
#include "commit.h"
#include "tag.h"
@@ -63,6 +64,9 @@ int cmd_merge_recursive(int argc, const char **argv, const char *prefix)
if (argc - i != 3) /* "--" "<head>" "<remote>" */
die(_("not handling anything other than two heads merge."));
+ if (repo_read_index_unmerged(the_repository))
+ die_resolve_conflict("merge");
+
o.branch1 = argv[++i];
o.branch2 = argv[++i];
diff --git a/builtin/stash.c b/builtin/stash.c
index b5a301f24d..4aa47785f9 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -427,6 +427,8 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
return error(_("could not save index tree"));
reset_head();
+ discard_cache();
+ read_cache();
}
}
diff --git a/t/t3030-merge-recursive.sh b/t/t3030-merge-recursive.sh
index ff641b348a..a37bcc58a0 100755
--- a/t/t3030-merge-recursive.sh
+++ b/t/t3030-merge-recursive.sh
@@ -667,15 +667,22 @@ test_expect_success 'merging with triple rename across D/F conflict' '
test_expect_success 'merge-recursive remembers the names of all base trees' '
git reset --hard HEAD &&
+ # make the index match $c1 so that merge-recursive below does not
+ # fail early
+ git diff --binary HEAD $c1 -- | git apply --cached &&
+
# more trees than static slots used by oid_to_hex()
for commit in $c0 $c2 $c4 $c5 $c6 $c7
do
git rev-parse "$commit^{tree}"
done >trees &&
- # ignore the return code -- it only fails because the input is weird
+ # ignore the return code; it only fails because the input is weird...
test_must_fail git -c merge.verbosity=5 merge-recursive $(cat trees) -- $c1 $c3 >out &&
+ # ...but make sure it fails in the expected way
+ test_i18ngrep CONFLICT.*rename/rename out &&
+
# merge-recursive prints in reverse order, but we do not care
sort <trees >expect &&
sed -n "s/^virtual //p" out | sort >actual &&
--
2.22.0.550.g71c37a0928.dirty
next prev parent reply other threads:[~2019-07-26 15:53 UTC|newest]
Thread overview: 157+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-25 17:45 [PATCH 00/19] Cleanup merge API Elijah Newren
2019-07-25 17:45 ` [PATCH 01/19] merge-recursive: fix minor memory leak in error condition Elijah Newren
2019-07-25 17:45 ` [PATCH 02/19] merge-recursive: remove another implicit dependency on the_repository Elijah Newren
2019-07-25 17:45 ` [PATCH 03/19] Ensure index matches head before invoking merge machinery, round N Elijah Newren
2019-07-25 19:41 ` Johannes Schindelin
2019-07-25 19:58 ` Elijah Newren
2019-07-26 11:23 ` Johannes Schindelin
2019-07-25 17:45 ` [PATCH 04/19] merge-recursive: exit early if index != head Elijah Newren
2019-07-25 19:51 ` Johannes Schindelin
2019-07-25 20:12 ` Elijah Newren
2019-07-25 17:45 ` [PATCH 05/19] merge-recursive: don't force external callers to do our logging Elijah Newren
2019-07-25 17:45 ` [PATCH 06/19] Change call signature of write_tree_from_memory() Elijah Newren
2019-07-25 19:55 ` Johannes Schindelin
2019-07-26 4:58 ` Elijah Newren
2019-07-25 17:45 ` [PATCH 07/19] Move write_tree_from_memory() from merge-recursive to cache-tree Elijah Newren
2019-07-25 17:46 ` [PATCH 08/19] merge-recursive: fix some overly long lines Elijah Newren
2019-07-25 17:46 ` [PATCH 09/19] merge-recursive: use common name for ancestors/common/base_list Elijah Newren
2019-07-25 17:46 ` [PATCH 10/19] merge-recursive: rename 'mrtree' to 'result_tree', for clarity Elijah Newren
2019-07-25 20:02 ` Johannes Schindelin
2019-07-25 17:46 ` [PATCH 11/19] merge-recursive: rename merge_options argument to opt in header Elijah Newren
2019-07-25 17:46 ` [PATCH 12/19] merge-recursive: move some definitions around to clean up the header Elijah Newren
2019-07-25 17:46 ` [PATCH 13/19] merge-recursive: consolidate unnecessary fields in merge_options Elijah Newren
2019-07-25 17:46 ` [PATCH 14/19] merge-recursive: comment and reorder the merge_options fields Elijah Newren
2019-07-25 17:46 ` [PATCH 15/19] merge-recursive: split internal fields into a separate struct Elijah Newren
2019-07-25 20:12 ` Johannes Schindelin
2019-07-25 20:27 ` Elijah Newren
2019-07-26 11:25 ` Johannes Schindelin
2019-07-26 15:30 ` Elijah Newren
2019-07-25 17:46 ` [PATCH 16/19] merge-recursive: alphabetize include list Elijah Newren
2019-07-25 17:46 ` [PATCH 17/19] merge-recursive: rename MERGE_RECURSIVE_* to MERGE_VARIANT_* Elijah Newren
2019-07-25 17:46 ` [PATCH 18/19] merge-recursive: be consistent with assert Elijah Newren
2019-07-25 17:46 ` [PATCH 19/19] merge-recursive: provide a better label for diff3 common ancestor Elijah Newren
2019-07-25 20:28 ` Johannes Schindelin
2019-07-25 18:12 ` [PATCH 00/19] Cleanup merge API Junio C Hamano
2019-07-25 19:06 ` Elijah Newren
2019-07-25 22:50 ` Junio C Hamano
2019-07-26 14:07 ` Johannes Schindelin
2019-07-25 19:15 ` Johannes Schindelin
2019-07-26 15:15 ` Elijah Newren
2019-07-26 15:52 ` [PATCH v2 00/20] " Elijah Newren
2019-07-26 15:52 ` [PATCH v2 01/20] merge-recursive: fix minor memory leak in error condition Elijah Newren
2019-07-26 18:31 ` Junio C Hamano
2019-07-26 23:19 ` Elijah Newren
2019-07-29 14:13 ` Derrick Stolee
2019-07-26 15:52 ` [PATCH v2 02/20] merge-recursive: remove another implicit dependency on the_repository Elijah Newren
2019-07-26 18:42 ` Junio C Hamano
2019-07-26 15:52 ` Elijah Newren [this message]
2019-07-26 19:14 ` [PATCH v2 03/20] Ensure index matches head before invoking merge machinery, round N Junio C Hamano
2019-07-26 23:22 ` Elijah Newren
2019-07-26 15:52 ` [PATCH v2 04/20] merge-recursive: exit early if index != head Elijah Newren
2019-07-26 19:32 ` Junio C Hamano
2019-07-26 23:26 ` Elijah Newren
2019-07-29 15:56 ` Junio C Hamano
2019-07-26 15:52 ` [PATCH v2 05/20] merge-recursive: remove useless parameter in merge_trees() Elijah Newren
2019-07-26 19:37 ` Junio C Hamano
2019-07-26 15:52 ` [PATCH v2 06/20] merge-recursive: don't force external callers to do our logging Elijah Newren
2019-07-26 19:57 ` Junio C Hamano
2019-07-26 23:28 ` Elijah Newren
2019-07-26 15:52 ` [PATCH v2 07/20] Use write_index_as_tree() in lieu of write_tree_from_memory() Elijah Newren
2019-07-26 20:11 ` Junio C Hamano
2019-07-26 23:39 ` Elijah Newren
2019-07-29 4:46 ` Junio C Hamano
2019-07-26 15:52 ` [PATCH v2 08/20] merge-recursive: fix some overly long lines Elijah Newren
2019-07-26 15:52 ` [PATCH v2 09/20] merge-recursive: use common name for ancestors/common/base_list Elijah Newren
2019-07-26 15:52 ` [PATCH v2 10/20] merge-recursive: rename 'mrtree' to 'result_tree', for clarity Elijah Newren
2019-07-26 15:52 ` [PATCH v2 11/20] merge-recursive: rename merge_options argument to opt in header Elijah Newren
2019-07-26 15:52 ` [PATCH v2 12/20] merge-recursive: move some definitions around to clean up the header Elijah Newren
2019-07-26 15:52 ` [PATCH v2 13/20] merge-recursive: consolidate unnecessary fields in merge_options Elijah Newren
2019-07-26 15:52 ` [PATCH v2 14/20] merge-recursive: comment and reorder the merge_options fields Elijah Newren
2019-07-26 15:52 ` [PATCH v2 15/20] merge-recursive: avoid losing output and leaking memory holding that output Elijah Newren
2019-07-26 15:52 ` [PATCH v2 16/20] merge-recursive: split internal fields into a separate struct Elijah Newren
2019-07-26 15:52 ` [PATCH v2 17/20] merge-recursive: alphabetize include list Elijah Newren
2019-07-26 15:52 ` [PATCH v2 18/20] merge-recursive: rename MERGE_RECURSIVE_* to MERGE_VARIANT_* Elijah Newren
2019-07-26 15:52 ` [PATCH v2 19/20] merge-recursive: be consistent with assert Elijah Newren
2019-07-26 15:52 ` [PATCH v2 20/20] merge-recursive: provide a better label for diff3 common ancestor Elijah Newren
2019-08-15 21:40 ` [PATCH v3 00/24] Clean up merge API Elijah Newren
2019-08-15 21:40 ` [PATCH v3 01/24] merge-recursive: be consistent with assert Elijah Newren
2019-08-15 21:40 ` [PATCH v3 02/24] checkout: provide better conflict hunk description with detached HEAD Elijah Newren
2019-08-15 21:40 ` [PATCH v3 03/24] merge-recursive: enforce opt->ancestor != NULL when calling merge_trees() Elijah Newren
2019-08-16 21:05 ` Junio C Hamano
2019-08-15 21:40 ` [PATCH v3 04/24] merge-recursive: provide a better label for diff3 common ancestor Elijah Newren
2019-08-16 21:33 ` Junio C Hamano
2019-08-16 22:39 ` Elijah Newren
2019-08-15 21:40 ` [PATCH v3 05/24] merge-recursive: introduce an enum for detect_directory_renames values Elijah Newren
2019-08-15 21:40 ` [PATCH v3 06/24] merge-recursive: future-proof update_file_flags() against memory leaks Elijah Newren
2019-08-15 21:40 ` [PATCH v3 07/24] merge-recursive: remove another implicit dependency on the_repository Elijah Newren
2019-08-15 21:40 ` [PATCH v3 08/24] Ensure index matches head before invoking merge machinery, round N Elijah Newren
2019-08-15 21:40 ` [PATCH v3 09/24] merge-recursive: exit early if index != head Elijah Newren
2019-08-15 21:40 ` [PATCH v3 10/24] merge-recursive: remove useless parameter in merge_trees() Elijah Newren
2019-08-15 21:40 ` [PATCH v3 11/24] merge-recursive: don't force external callers to do our logging Elijah Newren
2019-08-15 21:40 ` [PATCH v3 12/24] cache-tree: share code between functions writing an index as a tree Elijah Newren
2019-08-16 22:01 ` Junio C Hamano
2019-08-16 22:39 ` Elijah Newren
2019-08-15 21:40 ` [PATCH v3 13/24] merge-recursive: fix some overly long lines Elijah Newren
2019-08-15 21:40 ` [PATCH v3 14/24] merge-recursive: use common name for ancestors/common/base_list Elijah Newren
2019-08-15 21:40 ` [PATCH v3 15/24] merge-recursive: rename 'mrtree' to 'result_tree', for clarity Elijah Newren
2019-08-15 21:40 ` [PATCH v3 16/24] merge-recursive: rename merge_options argument to opt in header Elijah Newren
2019-08-15 21:40 ` [PATCH v3 17/24] merge-recursive: move some definitions around to clean up the header Elijah Newren
2019-08-15 21:40 ` [PATCH v3 18/24] merge-recursive: consolidate unnecessary fields in merge_options Elijah Newren
2019-08-16 22:14 ` Junio C Hamano
2019-08-16 22:59 ` Elijah Newren
2019-08-16 23:24 ` Junio C Hamano
2019-08-15 21:40 ` [PATCH v3 19/24] merge-recursive: comment and reorder the merge_options fields Elijah Newren
2019-08-15 21:40 ` [PATCH v3 20/24] merge-recursive: avoid losing output and leaking memory holding that output Elijah Newren
2019-08-15 21:40 ` [PATCH v3 21/24] merge-recursive: split internal fields into a separate struct Elijah Newren
2019-08-16 21:19 ` SZEDER Gábor
2019-08-16 23:00 ` Elijah Newren
2019-08-16 22:17 ` Junio C Hamano
2019-08-15 21:40 ` [PATCH v3 22/24] merge-recursive: rename MERGE_RECURSIVE_* to MERGE_VARIANT_* Elijah Newren
2019-08-15 21:40 ` [PATCH v3 23/24] merge-recursive: add sanity checks for relevant merge_options Elijah Newren
2019-08-16 19:52 ` Junio C Hamano
2019-08-16 22:08 ` Elijah Newren
2019-08-16 23:15 ` Junio C Hamano
2019-08-16 19:59 ` Junio C Hamano
2019-08-16 22:09 ` Elijah Newren
2019-08-15 21:40 ` [PATCH v3 24/24] merge-recursive: alphabetize include list Elijah Newren
2019-08-17 18:41 ` [PATCH v4 00/24] Clean up merge API Elijah Newren
2019-08-17 18:41 ` [PATCH v4 01/24] merge-recursive: be consistent with assert Elijah Newren
2019-08-17 18:41 ` [PATCH v4 02/24] checkout: provide better conflict hunk description with detached HEAD Elijah Newren
2019-08-17 18:41 ` [PATCH v4 03/24] merge-recursive: enforce opt->ancestor != NULL when calling merge_trees() Elijah Newren
2019-08-17 18:41 ` [PATCH v4 04/24] merge-recursive: provide a better label for diff3 common ancestor Elijah Newren
2019-09-30 21:14 ` Jeff King
2019-09-30 21:19 ` Jeff King
2019-09-30 22:54 ` [PATCH] merge-recursive: fix the diff3 common ancestor label for virtual commits Elijah Newren
2019-10-01 6:56 ` Elijah Newren
2019-10-01 6:58 ` [PATCH v2] " Elijah Newren
2019-10-01 14:49 ` Jeff King
2019-10-01 18:17 ` [PATCH v3] " Elijah Newren
2019-10-07 2:51 ` Junio C Hamano
2019-10-07 15:52 ` [PATCH] merge-recursive: fix the fix to the diff3 common ancestor label Elijah Newren
2019-10-08 2:32 ` Junio C Hamano
2019-10-08 2:36 ` Junio C Hamano
2019-10-08 16:16 ` Elijah Newren
2019-08-17 18:41 ` [PATCH v4 05/24] merge-recursive: introduce an enum for detect_directory_renames values Elijah Newren
2019-08-17 18:41 ` [PATCH v4 06/24] merge-recursive: future-proof update_file_flags() against memory leaks Elijah Newren
2019-08-17 18:41 ` [PATCH v4 07/24] merge-recursive: remove another implicit dependency on the_repository Elijah Newren
2019-08-17 18:41 ` [PATCH v4 08/24] Ensure index matches head before invoking merge machinery, round N Elijah Newren
2019-09-02 23:01 ` Johannes Schindelin
2019-09-03 13:34 ` Johannes Schindelin
2019-09-03 18:17 ` Elijah Newren
2019-08-17 18:41 ` [PATCH v4 09/24] merge-recursive: exit early if index != head Elijah Newren
2019-08-17 18:41 ` [PATCH v4 10/24] merge-recursive: remove useless parameter in merge_trees() Elijah Newren
2019-08-17 18:41 ` [PATCH v4 11/24] merge-recursive: don't force external callers to do our logging Elijah Newren
2019-08-17 18:41 ` [PATCH v4 12/24] cache-tree: share code between functions writing an index as a tree Elijah Newren
2019-08-17 18:41 ` [PATCH v4 13/24] merge-recursive: fix some overly long lines Elijah Newren
2019-08-17 18:41 ` [PATCH v4 14/24] merge-recursive: use common name for ancestors/common/base_list Elijah Newren
2019-08-17 18:41 ` [PATCH v4 15/24] merge-recursive: rename 'mrtree' to 'result_tree', for clarity Elijah Newren
2019-08-17 18:41 ` [PATCH v4 16/24] merge-recursive: rename merge_options argument to opt in header Elijah Newren
2019-08-17 18:41 ` [PATCH v4 17/24] merge-recursive: move some definitions around to clean up the header Elijah Newren
2019-08-17 18:41 ` [PATCH v4 18/24] merge-recursive: consolidate unnecessary fields in merge_options Elijah Newren
2019-08-17 18:41 ` [PATCH v4 19/24] merge-recursive: comment and reorder the merge_options fields Elijah Newren
2019-08-17 18:41 ` [PATCH v4 20/24] merge-recursive: avoid losing output and leaking memory holding that output Elijah Newren
2019-08-17 18:41 ` [PATCH v4 21/24] merge-recursive: split internal fields into a separate struct Elijah Newren
2019-08-19 17:17 ` Junio C Hamano
2019-08-17 18:41 ` [PATCH v4 22/24] merge-recursive: rename MERGE_RECURSIVE_* to MERGE_VARIANT_* Elijah Newren
2019-08-17 18:41 ` [PATCH v4 23/24] merge-recursive: add sanity checks for relevant merge_options Elijah Newren
2019-08-17 18:41 ` [PATCH v4 24/24] merge-recursive: alphabetize include list 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=20190726155258.28561-4-newren@gmail.com \
--to=newren@gmail.com \
--cc=Johannes.Schindelin@gmx.de \
--cc=git@vger.kernel.org \
--cc=gitster@pobox.com \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).