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t6425 was very picky about the exact output message produced by a
rename/delete conflict, in a way that just scratches the surface of the
mess that was built into merge-recursive. The idea was that it would
try to find the possible combinations of different conflict types, and
when more than one was present for one path, it would try to provide a
combined message that covered all the cases.
There's a lot to unravel here...
First, there's a basic conflict type known as modify/delete, which is a
content conflict. It occurs when one side deletes a file, but the other
modifies it.
There is also a path conflict known as a rename/delete. This occurs
when one side deletes a path, and the other renames it. This is not a
content conflict, it is a path conflict. It will often occur in
combination with a content conflict, though, namely a modify/delete. As
such, these two were often combined.
Another type of conflict that can exist is a directory/file conflict.
For example, one side adds a new file at some path, and the other side
of history adds a directory at the same path. The path that was "added"
could have been put there by a rename, though. Thus, we have the
possibility of a single path being affected by a modify/delete, a
rename/delete, and a directory/file conflict.
In part, this was a natural by-product of merge-recursive's design.
Since it was doing a four way merge with the contents of the working
tree being the fourth factor it had to consider, it had working tree
handling spread all over the code. It also had directory/file conflict
handling spread everywhere through all the other types of conflicts.
And our testsuite has a huge number of directory/file conflict tests
because trying to get them right required modifying so many different
codepaths. A natural outgrowth of this kind of structure is conflict
messages that combine all the different types that the current codepath
is considering.
However, if we want to make the different conflict types orthogonal and
avoid repeating ourselves and getting very brittle code, then we need to
split the messages from these different conflict types apart. Besides,
trying to determine all possible permutations is a _royal_ mess. The
code to handle the rename/delete/directory/file conflict output is
already somewhat hard to parse, and is somewhat brittle. But if we
really wanted to go that route, then we'd have to have special handling
for the following types of combinations:
* rename/add/delete:
on side of history that didn't rename the given file, remove the file
instead and place an unrelated file in the way of the rename
* rename/rename(2to1)/mode conflict/delete/delete:
two different files, one executable and the other not, are renamed
to the same location, each side deletes the source file that the
other side renames
* rename/rename(1to2)/add/add:
file renamed differently on each side of history, with each side
placing an unrelated file in the way of the other
* rename/rename(1to2)/content conflict/file location/(D/F)/(D/F)/:
both sides modify a file in conflicting way, both rename that file
but to different paths, one side renames the directory which the
other side had renamed that file into causing it to possibly need a
transitive rename, and each side puts a directory in the way of the
other's path.
Let's back away from this path of insanity, and allow the different
types of conflicts to be handled by separate pieces of non-repeated code
by allowing the conflict messages to be split into their separate types.
(If multiple conflict types affect a single path, the conflict messages
can be printed sequentially.) Start this path with a simple change:
modify this test to be more flexible and accept the output either merge
backend (recursive or the new ort) will produce.
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