There are multiple issues at play here:
1) If `git merge` is invoked with staged changes, it should abort
without doing any merging, and the user's working tree and index
should be the same as before merge was invoked.
2) Merge strategies are responsible for enforcing the index == HEAD
requirement. (See 9822175d2b ("Ensure index matches head before
invoking merge machinery, round N", 2019-08-17) for some history
around this.)
3) Merge strategies can bail saying they are not an appropriate
handler for the merge in question (possibly allowing other
strategies to be used instead).
4) Merge strategies can make changes to the index and working tree,
and have no expectation to clean up after themselves, *even* if
they bail out and say they are not an appropriate handler for
the merge in question. (The `octopus` merge strategy does this,
for example.)
5) Because of (3) and (4), builtin/merge.c stashes state before
trying merge strategies and restores it afterward.
Unfortunately, if users had staged changes before calling `git merge`,
builtin/merge.c could do the following:
* stash the changes, in order to clean up after the strategies
* try all the merge strategies in turn, each of which report they
cannot function due to the index not matching HEAD
* restore the changes via "git stash apply"
But that last step would have the net effect of unstaging the user's
changes. Fix this by adding the "--index" option to "git stash apply".
While at it, also squelch the stash apply output; we already report
"Rewinding the tree to pristine..." and don't need a detailed `git
status` report afterwards. Also while at it, switch to using strvec
so folks don't have to count the arguments to ensure we avoided an
off-by-one error, and so it's easier to add additional arguments to
the command.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When there are stat-dirty files, but no files are modified,
`git stash create` exits with unsuccessful status. This causes merge
to fail. Copy some code from sequencer.c's create_autostash to refresh
the index first to avoid this problem.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
builtin/merge is setup to allow multiple strategies to be specified,
and it will find the "best" result and use it. This is defeated if
some of the merge strategies abort early when they cannot handle the
merge. Fix the logic that calls recursive and ort to not do such an
early abort, but instead return "2" or "unhandled" so that the next
strategy can try to handle the merge.
Coming up with a testcase for this is somewhat difficult, since
recursive and ort both handle nearly any two-headed merge (there is
a separate code path that checks for non-two-headed merges and
already returns "2" for them). So use a somewhat synthetic testcase
of having the index not match HEAD before the merge starts, since all
merge strategies will abort for that.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As noted in the last commit and the links therein (especially commit
9822175d2b ("Ensure index matches head before invoking merge machinery,
round N", 2019-08-17), we have had a very long history of problems with
failing to enforce the requirement that index matches HEAD when starting
a merge.
The "trivial merge" logic in builtin/merge.c is yet another such case
we previously missed. Add a check for it to ensure it aborts if the
index does not match HEAD, and add a testcase where this fix is needed.
Note that the fix here would also incidentally be an alternative fix
for the testcase added in the last patch, but the fix in the last patch
is still needed when multiple merge strategies are in use, so tweak the
testcase from the previous commit so that it continues to exercise the
codepath added in the last commit.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As noted in commit 9822175d2b ("Ensure index matches head before
invoking merge machinery, round N", 2019-08-17), we have had a very
long history of problems with failing to enforce the requirement that
index matches HEAD when starting a merge. One of the commits
referenced in the long tale of issues arising from lax enforcement of
this requirement was commit 55f39cf755 ("merge: fix misleading
pre-merge check documentation", 2018-06-30), which tried to document
the requirement and noted there were some exceptions. As mentioned in
that commit message, the `resolve` strategy was the one strategy that
did not have an explicit index matching HEAD check, and the reason it
didn't was that I wasn't able to discover any cases where the
implementation would fail to catch the problem and abort, and didn't
want to introduce unnecessary performance overhead of adding another
check.
Well, today I discovered a testcase where the implementation does not
catch the problem and so an explicit check is needed. Add a testcase
that previously would have failed, and update git-merge-resolve.sh to
have an explicit check. Note that the code is copied from 3ec62ad9ff
("merge-octopus: abort if index does not match HEAD", 2016-04-09), so
that we reuse the same message and avoid making translators need to
translate some new message.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We do make sure that an attempt to merge with various forms of local
changes will "fail", but the point of stopping the merge is so that
we refrain from discarding uncommitted local changes that could be
precious. Add a few more checks for each case to make sure the
local changes are left intact.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Remove untracked files that are unwanted after they are done being used.
While the set of cases in this patch is certainly far from
comprehensive, it was motivated by some work to see what the fallout
would be if we were to make the removal of untracked files as a side
effect of other commands into an error. Some cases were a bit more
involved than the testcase changes included in this patch, but the ones
included here represent the simple cases. While this patch is not that
important since we are not changing the behavior of those other commands
into an error in the near term, I thought these changes were useful
anyway as an explicit documentation of the intent that these untracked
files are no longer useful.
Acked-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Acked-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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>
