In commit 7ca56aa076 ("merge-recursive: add a label for ancestor",
2010-03-20), a label was added for the '||||||' line to make it have
the more informative heading '|||||| merged common ancestors', with
the statement:
It would be nicer to use a more informative label. Perhaps someone
will provide one some day.
This chosen label was perfectly reasonable when recursiveness kicks in,
i.e. when there are multiple merge bases. (I can't think of a better
label in such cases.) But it is actually somewhat misleading when there
is a unique merge base or no merge base. Change this based on the
number of merge bases:
>=2: "merged common ancestors"
1: <abbreviated commit hash>
0: "<empty tree>"
Tests have also been added to check that we get the right ancestor name
for each of the three cases.
Also, since merge_recursive() and merge_trees() have polar opposite
pre-conditions for opt->ancestor, document merge_recursive()'s
pre-condition with an assertion. (An assertion was added to
merge_trees() already a few commits ago.) The differences in
pre-conditions stem from two factors: (1) merge_trees() does not recurse
and thus does not have multiple sub-merges to worry about -- each of
which would require a different value for opt->ancestor, (2)
merge_trees() is only passed trees rather than commits and thus cannot
internally guess as good of a label. Thus, while external callers of
merge_trees() are required to provide a non-NULL opt->ancestor,
merge_recursive() expects to set this value itself.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
b8cd1bb713 ("t6036, t6043: increase code coverage for file collision
handling", 2018-11-07) uses this GNU extension that is not available
in a POSIX complaint cp. In this particular case, there is no need to
use the option, as it is just copying a single file to create another
file.
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Stolee's coverage reports found a few code blocks for file collision
conflicts that had not previously been covered by testcases; add a few
more testcases to cover those too.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This makes the rename/rename(2to1) conflicts use the new
handle_file_collision() function. Since that function was based
originally on the rename/rename(2to1) handling code, the main
differences here are in what was added. In particular:
* Instead of storing files at collide_path~HEAD and collide_path~MERGE,
the files are two-way merged and recorded at collide_path.
* Instead of recording the version of the renamed file that existed
on the renamed side in the index (thus ignoring any changes that
were made to the file on the side of history without the rename),
we do a three-way content merge on the renamed path, then store
that at either stage 2 or stage 3.
* Note that since the content merge for each rename may have conflicts,
and then we have to merge the two renamed files, we can end up with
nested conflict markers.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This makes the rename/add conflict handling make use of the new
handle_file_collision() function, which fixes several bugs and improves
things for the rename/add case significantly. Previously, rename/add
would:
* Not leave any higher order stage entries in the index, making it
appear as if there were no conflict.
* Would place the rename file at the colliding path, and move the
added file elsewhere, which combined with the lack of higher order
stage entries felt really odd. It's not clear to me why the
rename should take precedence over the add; if one should be moved
out of the way, they both probably should.
* In the recursive case, it would do a two way merge of the added
file and the version of the renamed file on the renamed side,
completely excluding modifications to the renamed file on the
unrenamed side of history.
Use the new handle_file_collision() to fix all of these issues.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Later patches in this series will modify file collision conflict
handling (e.g. from rename/add and rename/rename(2to1) conflicts) so
that multiply nested conflict markers can arise even before considering
conflicts in the virtual merge base. Including the virtual merge base
will provide a way to get triply (or higher) nested conflict markers.
This new way to get nested conflict markers will force the need for a
more general mechanism to extend the length of conflict markers in order
to differentiate between different nestings.
Along with this change to conflict marker length handling, we want to
make sure that we don't regress handling for other types of conflicts
with nested conflict markers. Add a more involved testcase using
merge.conflictstyle=diff3, where not only does the virtual merge base
contain conflicts, but its virtual merge base does as well (i.e. a case
with triply nested conflict markers). While there are multiple
reasonable ways to handle nested conflict markers in the virtual merge
base for this type of situation, the easiest approach that dovetails
well with the new needs for the file collision conflict handling is to
require that the length of the conflict markers increase with each
subsequent nesting.
Subsequent patches which change the rename/add and rename/rename(2to1)
conflict handling will modify the extra_marker_size flag appropriately
for their new needs.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When a single file is renamed, it can also be modified, yielding the
possibility of that renamed file having content conflicts. If two
different such files are renamed into the same location, then two-way
merging those files may result in nested conflicts. Add a testcase that
makes sure we get this case correct, and uses different lengths of
conflict markers to differentiate between the different nestings.
Also add another case with an extra (i.e. third) level of conflict
markers due to using merge.conflictstyle=diff3 and the virtual merge
base also having conflicts present.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We want to load unmerged entries from HEAD into the index at stage 2 and
from MERGE_HEAD into stage 3. Similarly, folks expect merge conflicts
to look like
<<<<<<<< HEAD
content from our side
========
content from their side
>>>>>>>> MERGE_HEAD
not
<<<<<<<< MERGE_HEAD
content from their side
========
content from our side
>>>>>>>> HEAD
The correct order usually comes naturally and for free, but with renames
we often have data in the form {rename_branch, other_branch}, and
working relative to the rename first (e.g. for rename/add) is more
convenient elsewhere in the code. Address the slight impedance
mismatch by having some functions re-call themselves with flipped
arguments when the branch order is reversed.
Note that setup_rename_conflict_info() has one asymmetry in it, in
setting dst_entry1->processed=0 but not doing similarly for
dst_entry2->processed. When dealing with rename/rename and similar
conflicts, we do not want the processing to happen twice, so the
desire to only set one of the entries to unprocessed is intentional.
So, while this change modifies which branch's entry will be marked as
unprocessed, that dovetails nicely with putting HEAD first so that we
get the index stage entries and conflict markers in the right order.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Tests to cover various conflicting cases have been added for
merge-recursive.
* en/t6036-merge-recursive-tests:
t6036: add a failed conflict detection case: regular files, different modes
t6036: add a failed conflict detection case with conflicting types
t6036: add a failed conflict detection case with submodule add/add
t6036: add a failed conflict detection case with submodule modify/modify
t6036: add a failed conflict detection case with symlink add/add
t6036: add a failed conflict detection case with symlink modify/modify
There was a discussion of problematic directory/file conflicts with
virtual merge bases on the mailing list years ago at
https://public-inbox.org/git/AANLkTimwUQafGDrjxWrfU9uY1uKoFLJhxYs=vssOPqdf@mail.gmail.com/
Part of these corresponding tests made it into this testsuite. However,
the more problematic one didn't. And there are others that showcase the
problems even more. Add a very lengthy explanation, some of it from that
email, describing the tradeoffs in picking a recursive merge-base when
you're dealing with an add/add directory/file conflict.
The solution picked years ago is relatively good, but there is the
potential to do even better, assuming we're willing to pay a certain
performance cost.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
These tests reference non-existent object "c" when they really mean to
be referencing "C", however, these errors went unnoticed due to a broken
&&-chain later in the tests. Fix these errors, as well as the broken
&&-chains behind which they hid.
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Manually cleaning up from former tests in subsequent ones breaks the
ability to select which tests we want to run. Use test_when_finished to
avoid this problem.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
These tests used pretty strong measures to get a clean slate:
git rm -rf . &&
git clean -fdqx &&
rm -rf .git &&
git init &&
It's easier, safer (what if a previous test has a bug and accidentally
changes into a directory outside the test path?), and allows re-inspecting
test setup later if we instead just use test_create_repo to put different
tests into separate sub-repositories.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git rerere" can get confused by conflict markers deliberately left
by the inner merge step, because they are indistinguishable from
the real conflict markers left by the outermost merge which are
what the end user and "rerere" need to look at. This was fixed by
making the conflict markers left by the inner merges a bit longer.
* jc/ll-merge-internal:
t6036: remove pointless test that expects failure
ll-merge: use a longer conflict marker for internal merge
ll-merge: fix typo in comment
One test in t6036 prepares a file whose contents contain these
lines:
<<<<<<< Temporary merge branch 1
C
=======
B
>>>>>>> Temporary merge branch 2
and uses recursive merge strategy to run criss-cross merge with it.
Manual merge resolution by users fundamentally depends on being able
to distinguish the tracked contents from the separator lines added
by "git merge" in order to allow users to tell which block of lines
came from where. You can deliberately craft a file with lines that
resemble conflict marker lines to make it impossible for the user
(the outer merge of merge-recursive counts as a user of the result
of "virtual parent" merge) to tell which part is which, and write a
test to demonstrate that with such a file that "git merge" cannot
fundamentally work well and has to fail.
It however is pointless and waste of time and resource to run such a
test that asserts the obvious.
In real life, people who do need to track files with such lines that
have <<<< ==== >>>> as their prefixes set the conflict-marker-size
attribute to make sure they will be able to tell between the tracked
lines that happen to begin with these (confusing) prefixes and the
marker lines that are added by "git merge".
Remove the test as pointless waste of resource.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The primary use of conflict markers is to help the user who resolves
the final (outer) merge by hand to show which part came from which
branch by separating the blocks of lines apart. When the conflicted
parts from a "virtual ancestor" merge created by merge-recursive
remains in the common ancestor part in the final result, however,
the conflict markers that are the same size as the final merge
become harder to see.
Increase the conflict marker size slightly for these inner merges so
that the markers from the final merge and cruft from internal merge
can be distinguished more easily.
This would help reduce the common issue that prevents "rerere" from
being used on a really complex conflict.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
These test scripts likely predate test_must_fail, and can be
made simpler by using it (in addition to making them pass
--chain-lint).
The case in t6036 loses some verbosity in the failure case,
but it is so tied to a specific failure mode that it is not
worth keeping around (and the outcome of the test is not
affected at all).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
These are tests which are missing a link in their &&-chain,
but during a setup phase. We may fail to notice failure in
commands that build the test environment, but these are
typically not expected to fail at all (but it's still good
to double-check that our test environment is what we
expect).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
These are tests which are missing a link in their &&-chain,
in a location which causes a significant portion of the test
to be missed (e.g., the test effectively does nothing, or
consists of a long string of actions and output comparisons,
and we throw away the exit code of at least one part of the
string).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Earlier in this series, the patch "merge-recursive: add handling for
rename/rename/add-dest/add-dest" added code to handle the rename on each
side of history also being involved in a rename/add conflict, but only
did so in the non-recursive case. Add code for the recursive case,
ensuring that the "added" files are not simply deleted.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is another testcase trying to exercise the virtual merge base
creation in the rename/rename(1to2) code. A testcase is added that we
should be able to merge cleanly, but which requires a virtual merge base
to be created that correctly handles rename/add-dest conflicts within the
rename/rename(1to2) testcase handling.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Our previous conflict resolution for renaming two different files to the
same name ignored the fact that each of those files may have modifications
from both sides of history to consider. We need to do a three-way merge
for each of those files, and then handle the conflict of both sets of
merged contents trying to be recorded with the same name.
It is important to note that this changes our strategy in the recursive
case. After doing a three-way content merge of each of the files
involved, we still are faced with the fact that we are trying to put both
of the results (including conflict markers) into the same path. We could
do another two-way merge, but I think that becomes confusing. Also,
taking a hint from the modify/delete and rename/delete cases we handled
earlier, a more useful "common ground" would be to keep the three-way
content merge but record it with the original filename. The renames can
still be detected, we just allow it to be done in the o->call_depth=0
case. This seems to result in simpler & easier to understand merge
conflicts as well, as evidenced by some of the changes needed in our
testsuite in t6036. (However, it should be noted that this change will
cause problems those renames also occur along with a file being added
whose name matches the source of the rename. Since git currently cannot
detect rename/add-source situations, though, this codepath is not
currently used for those cases anyway.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When renaming one file to two files, we really should be doing a content
merge. Also, in the recursive case, undoing the renames and recording the
merged file in the index with the source of the rename (while deleting
both destinations) allows the renames to be re-detected in the
non-recursive merge and will result in fewer spurious conflicts.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When o->call_depth>0 and we have conflicts, we try to find "middle ground"
when creating the virtual merge base. In the case of content conflicts,
this can be done by doing a three-way content merge and using the result.
In all parts where the three-way content merge is clean, it is the correct
middle ground, and in parts where it conflicts there is no middle ground
but the conflict markers provide a good compromise since they are unlikely
to accidentally match any further changes.
In the case of a modify/delete conflict, we cannot do the same thing.
Accepting either endpoint as the resolution for the virtual merge base
runs the risk that when handling the non-recursive case we will silently
accept one person's resolution over another without flagging a conflict.
In this case, the closest "middle ground" we have is actually the merge
base of the candidate merge bases. (We could alternatively attempt a
three way content merge using an empty file in place of the deleted file,
but that seems to be more work than necessary.)
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The code for rename_rename_2to1 conflicts (two files both being renamed to
the same filename) was dead since the rename/add path was always being
independently triggered for each of the renames instead. Further,
reviving the dead code showed that it was inherently buggy and would
always segfault -- among a few other bugs.
Move the else-if branch for the rename/rename block before the rename/add
block to make sure it is checked first, and fix up the rename/rename(2to1)
code segments to make it handle most cases. Work is still needed to
handle higher dimensional corner cases such as rename/rename/modify/modify
issues.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If there were several files conflicting below a directory corresponding
to a D/F conflict, and the file of that D/F conflict is in the way, we
want it to be removed. Since files of D/F conflicts are handled last,
they can be reinstated later and possibly with a new unique name.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When a D/F conflict is introduced via an add/add conflict, when
o->call_depth > 0 we need to ensure that the higher stage entry from the
base stage is removed.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is another challenging testcase trying to exercise the virtual merge
base creation in the rename/rename(1to2) code. A testcase is added that
we should be able to merge cleanly, but which requires a virtual merge
base to be created that is aware of rename/rename(1to2)/add-source
conflicts and can handle those.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This test is mostly just designed for testing optimality of the virtual
merge base in the event of a rename/rename(1to2) conflict. The current
choice for resolving this in git seems somewhat confusing and suboptimal.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Current git will nuke an untracked file during a rename/delete conflict if
(a) there is an untracked file whose name matches the source of a rename
and (b) the merge is done in a certain direction. Add a simple testcase
demonstrating this bug.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* en/merge-recursive: (41 commits)
t6022: Use -eq not = to test output of wc -l
merge-recursive:make_room_for_directories - work around dumb compilers
merge-recursive: Remove redundant path clearing for D/F conflicts
merge-recursive: Make room for directories in D/F conflicts
handle_delete_modify(): Check whether D/F conflicts are still present
merge_content(): Check whether D/F conflicts are still present
conflict_rename_rename_1to2(): Fix checks for presence of D/F conflicts
conflict_rename_delete(): Check whether D/F conflicts are still present
merge-recursive: Delay modify/delete conflicts if D/F conflict present
merge-recursive: Delay content merging for renames
merge-recursive: Delay handling of rename/delete conflicts
merge-recursive: Move handling of double rename of one file to other file
merge-recursive: Move handling of double rename of one file to two
merge-recursive: Avoid doubly merging rename/add conflict contents
merge-recursive: Update merge_content() call signature
merge-recursive: Update conflict_rename_rename_1to2() call signature
merge-recursive: Structure process_df_entry() to handle more cases
merge-recursive: Have process_entry() skip D/F or rename entries
merge-recursive: New function to assist resolving renames in-core only
merge-recursive: New data structures for deferring of D/F conflicts
...
Conflicts:
t/t6020-merge-df.sh
t/t6036-recursive-corner-cases.sh
Breaks in a test assertion's && chain can potentially hide
failures from earlier commands in the chain.
Commands intended to fail should be marked with !, test_must_fail, or
test_might_fail. The examples in this patch do not require that.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When a commit moves A to B while another commit created B (or moved C to
B), and these two different commits serve as different merge-bases for a
later merge, c94736a (merge-recursive: don't segfault while handling
rename clashes 2009-07-30) added some special code to avoid segfaults.
Since that commit, the two versions of B are merged in place (which could
be potentially conflicting) and the intermediate result is used as the
virtual ancestor.
However, right before this special merge, try_merge was turned on, meaning
that process_renames() would try an alternative merge that ignores the
'add' part of the conflict, and, if the merge is clean, store that as the
new virtual ancestor. This could cause incorrect merging of criss-cross
merges; it would typically result in just recording a slightly confusing
merge base, but in some cases it could cause silent acceptance of one side
of a merge as the final resolution when a conflict should have been
flagged.
When we do a special merge for such a rename/add conflict between
merge-bases, turn try_merge off to avoid an inappropriate second merge.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If merging two lines of development involves a rename/add conflict, and two
different people make such a merge but resolve it differently, and then
someone tries to merge the resulting two merges, then they should clearly
get a conflict due to the different resolutions from the previous
developers. However, in some such cases the conflict would not be detected
and git would silently accept one of the two versions being merged as the
final merge resolution.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
