Previously, callers of the merge-ort API could have passed an
uninitialized value for struct merge_result *result. However, we want
to check result to see if it has cached renames from a previous merge
that we can reuse; such values would be found behind result->priv.
However, if result->priv is uninitialized, attempting to access behind
it will give a segfault. So, we need result->priv to be NULL (which
will be the case if the caller does a memset(&result, 0)), or be written
by a previous call to the merge-ort machinery. Documenting this
requirement may help, but despite being the person who introduced this
requirement, I still missed it once and it did not fail in a very clear
way and led to a long debugging session.
Add a _properly_initialized field to merge_result; that value will be
0 if the caller zero'ed the merge_result, it will be set to a very
specific value by a previous run by the merge-ort machinery, and if it's
uninitialized it will most likely either be 0 or some value that does
not match the specific one we'd expect allowing us to throw a much more
meaningful error.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Implement merge_incore_recursive(), mostly through the use of a new
helper function, merge_ort_internal(), which itself is based off
merge_recursive_internal() from merge-recursive.c.
This drops the number of failures in the testsuite when run under
GIT_TEST_MERGE_ALGORITHM=ort from around 1500 to 647.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Various places in merge-recursive used an err() function when it hit
some kind of unrecoverable error. That code was from the reusable bits
of merge-recursive.c that we liked, such as merge_3way, writing object
files to the object store, reading blobs from the object store, etc. So
create a similar function to allow us to port that code over, and use it
for when we detect problems returned from collect_merge_info()'s
traverse_trees() call, which we will be adding next.
While we are at it, also add more documentation for the "clean" field
from struct merge_result, particularly since the name suggests a boolean
but it is not quite one and this is our first non-boolean usage.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is the beginning of a new merge strategy. While there are some API
differences, and the implementation has some differences in behavior, it
is essentially meant as an eventual drop-in replacement for
merge-recursive.c. However, it is being built to exist side-by-side
with merge-recursive so that we have plenty of time to find out how
those differences pan out in the real world while people can still fall
back to merge-recursive. (Also, I intend to avoid modifying
merge-recursive during this process, to keep it stable.)
The primary difference noticable here is that the updating of the
working tree and index is not done simultaneously with the merge
algorithm, but is a separate post-processing step. The new API is
designed so that one can do repeated merges (e.g. during a rebase or
cherry-pick) and only update the index and working tree one time at the
end instead of updating it with every intermediate result. Also, one
can perform a merge between two branches, neither of which match the
index or the working tree, without clobbering the index or working tree.
The next three commits will demonstrate various uses of this new API.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
