Ever since commit 8c8e5bd6eb ("merge-recursive: switch directory
rename detection default", 2019-04-05), the default handling with
directory rename detection was to report a conflict and leave unstaged
entries in the index. However, when creating a virtual merge base in
the recursive case, we absolutely need a tree, and the only way a tree
can be written is if we have no unstaged entries -- otherwise we hit a
BUG().
There are a few fixes possible here which at least fix the BUG(), but
none of them seem optimal for other reasons; see the comments with the
new testcase 13e in t6043 for details (which testcase triggered a BUG()
prior to this patch). As such, just opt for a very conservative and
simple choice that is still relatively reasonable: have the recursive
case treat 'conflict' as 'false' for opt->detect_directory_renames.
Reported-by: Emily Shaffer <emilyshaffer@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When all of x/a, x/b, and x/c have moved to z/a, z/b, and z/c on one
branch, there is a question about whether x/d added on a different
branch should remain at x/d or appear at z/d when the two branches are
merged. There are different possible viewpoints here:
A) The file was placed at x/d; it's unrelated to the other files in
x/ so it doesn't matter that all the files from x/ moved to z/ on
one branch; x/d should still remain at x/d.
B) x/d is related to the other files in x/, and x/ was renamed to z/;
therefore x/d should be moved to z/d.
Since there was no ability to detect directory renames prior to
git-2.18, users experienced (A) regardless of context. Choice (B) was
implemented in git-2.18, with no option to go back to (A), and has been
in use since. However, one user reported that the merge results did not
match their expectations, making the change of default problematic,
especially since there was no notice printed when directory rename
detection moved files.
Note that there is also a third possibility here:
C) There are different answers depending on the context and content
that cannot be determined by git, so this is a conflict. Use a
higher stage in the index to record the conflict and notify the
user of the potential issue instead of silently selecting a
resolution for them.
Add an option for users to specify their preference for whether to use
directory rename detection, and default to (C). Even when directory
rename detection is on, add notice messages about files moved into new
directories.
As a sidenote, x/d did not have to be a new file here; it could have
already existed at some other path and been renamed to x/d, with
directory rename detection just renaming it again to z/d. Thus, it's
not just new files, but also a modification to all rename types (normal
renames, rename/add, rename/delete, rename/rename(1to1),
rename/rename(1to2), and rename/rename(2to1)).
Signed-off-by: Elijah Newren <newren@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>
When we have a rename/rename(1to2) conflict, each of the renames can
collide with a file addition. Each of these rename/add conflicts suffered
from the same kinds of problems that normal rename/add suffered from.
Make the code use handle_file_conflicts() as well so that we get all the
same fixes and consistent behavior between the different conflict types.
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>
The can-working-tree-updates-be-skipped check has had a long and blemished
history. The update can be skipped iff:
a) The merge is clean
b) The merge matches what was in HEAD (content, mode, pathname)
c) The target path is usable (i.e. not involved in D/F conflict)
Traditionally, we split b into parts:
b1) The merged result matches the content and mode found in HEAD
b2) The merged target path existed in HEAD
Steps a & b1 are easy to check; we have always gotten those right. While
it is easy to overlook step c, this was fixed seven years ago with commit
4ab9a157d0 ("merge_content(): Check whether D/F conflicts are still
present", 2010-09-20). merge-recursive didn't have a readily available
way to directly check step b2, so various approximations were used:
* In commit b2c8c0a762 ("merge-recursive: When we detect we can skip
an update, actually skip it", 2011-02-28), it was noted that although
the code claimed it was skipping the update, it did not actually skip
the update. The code was made to skip it, but used lstat(path, ...)
as an approximation to path-was-tracked-in-index-before-merge.
* In commit 5b448b8530 ("merge-recursive: When we detect we can skip
an update, actually skip it", 2011-08-11), the problem with using
lstat was noted. It was changed to the approximation
path2 && strcmp(path, path2)
which is also wrong. !path2 || strcmp(path, path2) would have been
better, but would have fallen short with directory renames.
* In c5b761fb27 ("merge-recursive: ensure we write updates for
directory-renamed file", 2018-02-14), the problem with the previous
approximation was noted and changed to
was_tracked(path)
That looks close to what we were trying to answer, but was_tracked()
as implemented at the time should have been named is_tracked(); it
returned something different than what we were looking for.
* To make matters more complex, fixing was_tracked() isn't sufficient
because the splitting of b into b1 and b2 is wrong. Consider the
following merge with a rename/add conflict:
side A: modify foo, add unrelated bar
side B: rename foo->bar (but don't modify the mode or contents)
In this case, the three-way merge of original foo, A's foo, and B's
bar will result in a desired pathname of bar with the same
mode/contents that A had for foo. Thus, A had the right mode and
contents for the file, and it had the right pathname present (namely,
bar), but the bar that was present was unrelated to the contents, so
the working tree update was not skippable.
Fix this by introducing a new function:
was_tracked_and_matches(o, path, &mfi.oid, mfi.mode)
and use it to directly check for condition b.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If a file on one side of history was renamed, and merely modified on the
other side, then applying a directory rename to the modified side gives us
a rename/rename(1to2) conflict. We should only apply directory renames to
pairs representing either adds or renames.
Making this change means that a directory rename testcase that was
previously reported as a rename/delete conflict will now be reported as a
modify/delete conflict.
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a testcase showing spurious rename/rename(1to2) conflicts occurring
due to directory rename detection.
Also add a pair of testcases dealing with moving directory hierarchies
around that were suggested by Stefan Beller as "food for thought" during
his review of an earlier patch series, but which actually uncovered a
bug. Round things out with a test that is a cross between the two
testcases that showed existing bugs in order to make sure we aren't
merely addressing problems in isolation but in general.
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This fixes an issue that existed before my directory rename detection
patches that affects both normal renames and renames implied by
directory rename detection. Additional codepaths that only affect
overwriting of dirty files that are involved in directory rename
detection will be added in a subsequent commit.
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit hooks together all the directory rename logic by making the
necessary changes to the rename struct, it's dst_entry, and the
diff_filepair under consideration.
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Before trying to apply directory renames to paths within the given
directories, we want to make sure that there aren't conflicts at the
file level either. If there aren't any, then get the new name from
any directory renames.
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
I came up with the testcases in the first eight sections before coding up
the implementation. The testcases in this section were mostly ones I
thought of while coding/debugging, and which I was too lazy to insert
into the previous sections because I didn't want to re-label with all the
testcase references. :-)
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a long note about why we are not considering "partial directory
renames" for the current directory rename detection implementation.
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This reverts commit e4bb62fa1e, reversing
changes made to 468165c1d8.
The topic appears to inflict severe regression in renaming merges,
even though the promise of it was that it would improve them.
We do not yet know which exact change in the topic was wrong, but in
the meantime, let's play it safe and revert it out of 'master'
before real Git-using projects are harmed.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When a file is present in HEAD before the merge and the other side of the
merge does not modify that file, we try to avoid re-writing the file and
making it stat-dirty. However, when a file is present in HEAD before the
merge and was in a directory that was renamed by the other side of the
merge, we have to move the file to a new location and re-write it.
Update the code that checks whether we can skip the update to also work in
the presence of directory renames.
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If a file on one side of history was renamed, and merely modified on the
other side, then applying a directory rename to the modified side gives us
a rename/rename(1to2) conflict. We should only apply directory renames to
pairs representing either adds or renames.
Making this change means that a directory rename testcase that was
previously reported as a rename/delete conflict will now be reported as a
modify/delete conflict.
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a testcase showing spurious rename/rename(1to2) conflicts occurring
due to directory rename detection.
Also add a pair of testcases dealing with moving directory hierarchies
around that were suggested by Stefan Beller as "food for thought" during
his review of an earlier patch series, but which actually uncovered a
bug. Round things out with a test that is a cross between the two
testcases that showed existing bugs in order to make sure we aren't
merely addressing problems in isolation but in general.
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This fixes an issue that existed before my directory rename detection
patches that affects both normal renames and renames implied by
directory rename detection. Additional codepaths that only affect
overwriting of dirty files that are involved in directory rename
detection will be added in a subsequent commit.
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit hooks together all the directory rename logic by making the
necessary changes to the rename struct, it's dst_entry, and the
diff_filepair under consideration.
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Before trying to apply directory renames to paths within the given
directories, we want to make sure that there aren't conflicts at the
file level either. If there aren't any, then get the new name from
any directory renames.
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
I came up with the testcases in the first eight sections before coding up
the implementation. The testcases in this section were mostly ones I
thought of while coding/debugging, and which I was too lazy to insert
into the previous sections because I didn't want to re-label with all the
testcase references. :-)
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a long note about why we are not considering "partial directory
renames" for the current directory rename detection implementation.
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
