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Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Similar to the previous commit, since the "recursive" backend relies on
unpack_trees() to check if unstaged or untracked files would be
overwritten by a merge, and unpack_trees() does not understand renames
-- it has false positives and false negatives. Once it has run, since
it updates as it goes, merge-recursive then has to handle completing the
merge as best it can despite extra changes in the working copy.
However, this is not just an issue for dirty files, but also for
untracked files because directory renames can cause file contents to
need to be written to a location that was not tracked on either side of
history.
Since the "ort" backend does the complete merge inmemory, and only
updates the index and working copy as a post-processing step, if there
are untracked files in the way it can simply abort the merge much like
checkout does.
Update t6423 to reflect the better merge abilities and expectations for
ort, while still leaving the best-case-as-good-as-recursive-can-do
expectations there for the recursive backend so we retain its stability
until we are ready to deprecate and remove it.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The "recursive" backend relies on unpack_trees() to check if unstaged
changes would be overwritten by a merge, but unpack_trees() does not
understand renames -- and once it returns, it has already written many
updates to the working tree and index. As such, "recursive" had to do a
special 4-way merge where it would need to also treat the working copy
as an extra source of differences that we had to carefully avoid
overwriting and resulting in moving files to new locations to avoid
conflicts.
The "ort" backend, by contrast, does the complete merge inmemory, and
only updates the index and working copy as a post-processing step. If
there are dirty files in the way, it can simply abort the merge.
Update t6423 and t6436 to reflect the better merge abilities and
expectations we have for ort, while still leaving the
best-case-as-good-as-recursive-can-do expectations there for the
recursive backend so we retain its stability until we are ready to
deprecate and remove it.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Conflict markers carry an extra annotation of the form
REF-OR-COMMIT:FILENAME
to help distinguish where the content is coming from, with the :FILENAME
piece being left off if it is the same for both sides of history (thus
only renames with content conflicts carry that part of the annotation).
However, there were cases where the :FILENAME annotation was
accidentally left off, due to merge-recursive's
every-codepath-needs-a-copy-of-all-special-case-code format.
Update a few tests to have the correct :FILENAME extension on relevant
paths with the ort backend, while leaving the expectation for
merge-recursive the same to avoid destabilizing it.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When a file is renamed and has content conflicts, merge-recursive does
not have some stages for the old filename and some stages for the new
filename in the index; instead it copies all the stages corresponding to
the old filename over to the corresponding locations for the new
filename, so that there are three higher order stages all corresponding
to the new filename. Doing things this way makes it easier for the user
to access the different versions and to resolve the conflict (no need to
manually 'git rm' the old version as well as 'git add' the new one).
rename/deletes should be handled similarly -- there should be two stages
for the renamed file rather than just one. We do not want to
destabilize merge-recursive right now, so instead update relevant tests
to have different expectations depending on whether the "recursive" or
"ort" merge strategies are in use.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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merge-recursive.c is built on the idea of running unpack_trees() and
then "doing minor touch-ups" to get the result. Unfortunately,
unpack_trees() was run in an update-as-it-goes mode, leading
merge-recursive.c to follow suit and end up with an immediate evaluation
and fix-it-up-as-you-go design. Some things like directory/file
conflicts are not well representable in the index data structure, and
required special extra code to handle. But then when it was discovered
that rename/delete conflicts could also be involved in directory/file
conflicts, the special directory/file conflict handling code had to be
copied to the rename/delete codepath. ...and then it had to be copied
for modify/delete, and for rename/rename(1to2) conflicts, ...and yet it
still missed some. Further, when it was discovered that there were also
file/submodule conflicts and submodule/directory conflicts, we needed to
copy the special submodule handling code to all the special cases
throughout the codebase.
And then it was discovered that our handling of directory/file conflicts
was suboptimal because it would create untracked files to store the
contents of the conflicting file, which would not be cleaned up if
someone were to run a 'git merge --abort' or 'git rebase --abort'. It
was also difficult or scary to try to add or remove the index entries
corresponding to these files given the directory/file conflict in the
index. But changing merge-recursive.c to handle these correctly was a
royal pain because there were so many sites in the code with similar but
not identical code for handling directory/file/submodule conflicts that
would all need to be updated.
I have worked hard to push all directory/file/submodule conflict
handling in merge-ort through a single codepath, and avoid creating
untracked files for storing tracked content (it does record things at
alternate paths, but makes sure they have higher-order stages in the
index).
Since updating merge-recursive is too much work and we don't want to
destabilize it, instead update the testsuite to have different
expectations for relevant directory/file/submodule conflict tests.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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There are a number of tests that the "recursive" backend does not handle
correctly but which the redesign in "ort" will. Add a new helper in
lib-merge.sh for selecting a different test expectation based on the
setting of GIT_TEST_MERGE_ALGORITHM, and use it in various testcases to
document which ones we expect to fail under recursive but pass under
ort.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Testcases 12b and 12c were both slightly weird; they were marked as
having a weird resolution, but with the note that even straightforward
simple rules can give weird results when the input is bizarre.
However, during optimization work for merge-ort, I discovered a
significant speedup that is possible if we add one more fairly
straightforward rule: we don't bother doing directory rename detection
if there are no new files added to the directory on the other side of
the history to be affected by the directory rename. This seems like an
obvious and straightforward rule, but there was one funny corner case
where directory rename detection could affect only existing files: the
funny corner case where two directories are renamed into each other on
opposite sides of history. In other words, it only results in a
different output for testcases 12b and 12c.
Since we already thought testcases 12b and 12c were weird anyway, and
because the optimization often has a significant effect on common cases
(but is entirely prevented if we can't change how 12b and 12c function),
let's add the additional rule and tweak how 12b and 12c work. Split
both testcases into two (one where we add no new files, and one where
the side that doesn't rename a given directory will add files to it),
and mark them with the new expectation.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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While investigating the issues highlighted by the testcase in the
previous patch, I also found a shortcoming in the directory rename
detection rules. Split testcase 6b into two to explain this issue
and update directory-rename-detection.txt to remove one of the previous
rules that I know believe to be detrimental. Also, update the wording
around testcase 8e; while we are not modifying the results of that
testcase, we were previously unsure of the appropriate resolution of
that test and the new rule makes the previously chosen resolution for
that testcase a bit more solid.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Add a new testcase modelled on a real world repository example that
served multiple purposes:
* it uncovered a bug in the current directory rename detection
implementation.
* it is a good test of needing to do directory rename detection for
a series of commits instead of just one (and uses rebase instead
of just merge like all the other tests in this testfile).
* it is an excellent stress test for some of the optimizations in
my new merge-ort engine
I can expand on the final item later when I have submitted more of
merge-ort, but the bug is the main immediate concern. It arises as
follows:
* dir/subdir/ has several files
* almost all files in dir/subdir/ are renamed to folder/subdir/
* one of the files in dir/subdir/ is renamed to folder/subdir/newsubdir/
* If the other side of history (that doesn't do the renames) adds a
new file to dir/subdir/, where should it be placed after the merge?
The most obvious two choices are: (1) leave the new file in dir/subdir/,
don't make it follow the rename, and (2) move the new file to
folder/subdir/, following the rename of most the files. However,
there's a possible third choice here: (3) move the new file to
folder/subdir/newsubdir/. The choice reinforce the fact that
merge.directoryRenames=conflict is a good default, but when the merge
machinery needs to stick it somewhere and notify the user of the
possibility that they might want to place it elsewhere. Surprisingly,
the current code would always choose (3), while the real world
repository was clearly expecting (2) -- move the file along with where
the herd of files was going, not with the special exception.
The problem here is that for the majority of the file renames,
dir/subdir/ -> folder/subdir/
is actually represented as
dir/ -> folder/
This directory rename would have a big weight associated with it since
most the files followed that rename. However, we always consult the
most immediate directory first, and there is only one rename rule for
it:
dir/subdir/ -> folder/subdir/newsubdir/
Since this rule is the only one for mapping from dir/subdir/, it
automatically wins and that directory rename was followed instead of the
desired dir/subdir/ -> folder/subdir/.
Unfortunately, the fix is a bit involved so for now just add the
testcase documenting the issue.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Much like the last commit accepted 'add/add' and 'rename/add'
interchangably, we also want to do the same for 'add/add' and
'rename/rename'. This also allows us to avoid the ambiguity in meaning
with 'rename/rename' (is it two separate files renamed to the same
location, or one file renamed on both sides but differently)?
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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I had long since forgotten the idea behind this test and why it failed,
and took a little while to figure it out. To prevent others from having
to spend a similar time on it, add an explanation in the comments.
However, the reasoning in the explanation makes me question why I
considered it a failure at all. I'm not sure if I had a better reason
when I originally wrote it, but for now just add commentary about the
possible expectations and why it behaves the way it does right now.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Commit da1e295e00 ("t604[236]: do not run setup in separate tests",
2019-10-22) removed approximately half the tests (which were setup-only
tests) in t6043 by turning them into functions that the subsequent test
would call as their first step. This ensured that any test from this
file could be run entirely independently of all the other tests in the
file. Unfortunately, the call to the new setup function was missed in
two of the test_expect_failure cases. Add them in.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The tests for the merge machinery are spread over several places.
Collect them into t64xx for simplicity. Some notes:
t60[234]*.sh:
Merge tests started in t602*, overgrew bisect and remote tracking
tests in t6030, t6040, and t6041, and nearly overtook replace tests
in t6050. This made picking out relevant tests that I wanted to run
in a tighter loop slightly more annoying for years.
t303*.sh:
These started out as tests for the 'merge-recursive' toplevel command,
but did not restrict to that and had lots of overlap with the
underlying merge machinery.
t7405, t7613:
submodule-specific merge logic started out in submodule.c but was
moved to merge-recursive.c in commit 18cfc08866 ("submodule.c: move
submodule merging to merge-recursive.c", 2018-05-15). Since these
tests are about the logic found in the merge machinery, moving these
tests to be with the merge tests makes sense.
t7607, t7609:
Having tests spread all over the place makes it more likely that
additional tests related to a certain piece of logic grow in all those
other places. Much like t303*.sh, these two tests were about the
underlying merge machinery rather than outer levels.
Tests that were NOT moved:
t76[01]*.sh:
Other than the four tests mentioned above, the remaining tests in
t76[01]*.sh are related to non-recursive merge strategies, parameter
parsing, and other stuff associated with the highlevel builtin/merge.c
rather than the recursive merge machinery.
t3[45]*.sh:
The rebase testcases in t34*.sh also test the merge logic pretty
heavily; sometimes changes I make only trigger failures in the rebase
tests. The rebase tests are already nicely coupled together, though,
and I didn't want to mess that up. Similar comments apply for the
cherry-pick tests in t35*.sh.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Elijah Newren