Junio C Hamano <gitster@xxxxxxxxx> writes:
> When they are called with non-zero o->call_depth, they are supposed to
> drop all the index entries that they handle down to stage #0 (even if the
> path had contents level conflict). For example, you see this bit in
> process_entry():
>
> } else if (a_sha && b_sha) {
> /* Case C: Added in both (check for same permissions) and */
> /* case D: Modified in both, but differently. */
> const char *reason = "content";
> ...
> mfi = merge_file(o, &one, &a, &b,
> o->branch1, o->branch2);
>
> clean_merge = mfi.clean;
> if (!mfi.clean) {
> if (S_ISGITLINK(mfi.mode))
> reason = "submodule";
> output(o, 1, "CONFLICT (%s): Merge conflict in %s",
> reason, path);
> }
> update_file(o, mfi.clean, mfi.sha, mfi.mode, path);
> } ...
>
> and update_file() eventually calls update_file_flags() to make sure that
> the content in mfi.sha is at the stage #0 of path when o->call_depth is
> non-zero (or mfi.clean is true). process_renames() and process_entry()
> are humongous functions that handle full of different cases, but all
> codepaths must follow the rule not to leave non-stage #0 entries in the
> index before merge_trees() function calls write_tree_from_memory().
>
> We've fixed a similar bug in c94736a (merge-recursive: don't segfault
> while handling rename clashes, 2009-07-30) and I think there were similar
> breakages we fixed over time in the same area, but the two functions being
> as huge as they are, I suspect you are hitting a codepath that hasn't been
> fixed.
And there are.
For example, this (drop it as t9999-junk.sh in t/ directory, go there and
run "sh ./t-9999-junk.sh -v") shows one codepath that makes merge-recursive
fail to resolve the "common ancestor" merge.
-- -- store in t/t9999-junk.sh and run -- --
#!/bin/sh
test_description='common ancestor merge corner cases'
. ./test-lib.sh
test_expect_success 'setup' '
mkdir D &&
echo 1 >D/F1 &&
echo 2 >D/F2 &&
echo 3 >D/F3 &&
echo 4 >D/F4 &&
echo 5 >D/F5 &&
echo 6 >D/F6 &&
git add D &&
test_tick &&
git commit -m initial &&
git branch side &&
git checkout master &&
git mv D/F1 D/M1 &&
git rm D/F2 &&
echo 7 >>D/F3 &&
git mv D/F4 D/M4 &&
git rm D/F5 &&
mkdir D/F5 &&
git mv D/F6 D/F5/M6 &&
git add -u &&
test_tick &&
git commit -m master &&
git tag A &&
git checkout side &&
git mv D/F1 D/S1 && # rename-rename conflict (dst)
echo 8 >>D/F2 && # remove-modify conflict
git mv D/F5 D/M4 && # rename-rename conflict (src)
git add -u &&
test_tick &&
git commit -m side &&
git tag B &&
git checkout side &&
test_tick &&
git merge -s ours master &&
git tag C &&
git checkout master &&
test_tick &&
git merge -s ours B &&
git tag D
'
test_expect_success 'criss-cross' '
git checkout D &&
test_must_fail git merge side
'
test_done
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
It dies after showing this (D/F5/M6 is left unresolved in the forced
"common ancestor" merge):
Merging:
f2f2f75 master
7994826 side
found 1 common ancestor(s):
f561e36 initial
CONFLICT (rename/rename): Rename "D/F1"->"D/M1" in branch "Temporary merge branch 1" rename "D/F1"->"D/S1" in "Temporary merge branch 2" (left unresolved)
CONFLICT (rename/add): Rename D/F4->D/M4 in Temporary merge branch 1. D/M4 added in Temporary merge branch 2
Adding merged D/M4
Skipped D/M4 (merged same as existing)
CONFLICT (rename/delete): Rename D/F5->D/M4 in Temporary merge branch 2 and deleted in Temporary merge branch 1
Skipped D/F5/M6 (merged same as existing)
CONFLICT (delete/modify): D/F2 deleted in Temporary merge branch 1 and modified in Temporary merge branch 2. Version Temporary merge branch 2 of D/F2 left in tree.
There are unmerged index entries:
2 D/F5/M6
The attached patch changes the behaviour to make this 9999-junk test pass,
but then it breaks t6036 (iow, the attached is _not_ a fix).
After I stared at the code for more than two hours, I gave up trying to
diagnose this by myself. People more familiar with the merge-recursive
implementation might be able to help figuring this out and may prove my
suspicion wrong, but I have a feeling that without a fairly big rewrite
the code is unsalvageable.
-- >8 --
Not a fix
diff --git a/merge-recursive.c b/merge-recursive.c
index 1239647..132a6fc 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1052,8 +1052,8 @@ static int process_renames(struct merge_options *o,
update_stages(ren1_dst,
one, a, b, 1);
}
- update_file(o, mfi.clean, mfi.sha, mfi.mode, ren1_dst);
}
+ update_file(o, mfi.clean, mfi.sha, mfi.mode, ren1_dst);
}
}
}
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