merge-recursive: Avoid doubly merging rename/add conflict contents

When a commit moves A to B while another commit created B (or moved C to
B), and these two different commits serve as different merge-bases for a
later merge, c94736a (merge-recursive: don't segfault while handling
rename clashes 2009-07-30) added some special code to avoid segfaults.
Since that commit, the two versions of B are merged in place (which could
be potentially conflicting) and the intermediate result is used as the
virtual ancestor.

However, right before this special merge, try_merge was turned on, meaning
that process_renames() would try an alternative merge that ignores the
'add' part of the conflict, and, if the merge is clean, store that as the
new virtual ancestor.  This could cause incorrect merging of criss-cross
merges; it would typically result in just recording a slightly confusing
merge base, but in some cases it could cause silent acceptance of one side
of a merge as the final resolution when a conflict should have been
flagged.

When we do a special merge for such a rename/add conflict between
merge-bases, turn try_merge off to avoid an inappropriate second merge.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/merge-recursive.c b/merge-recursive.c
index b9bc95a659bf2a76b20b64b4b2783bc3acb9a97c..6ffc67ade4dc0ceee604596d4a5fb6baad42ac43 100644 (file)
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1061,6 +1061,7 @@ static int process_renames(struct merge_options *o,
                                                    mfi.sha,
                                                    mfi.mode,
                                                    ren1_dst);
+                                       try_merge = 0;
                                } else {
                                        new_path = unique_path(o, ren1_dst, branch2);
                                        output(o, 1, "Adding as %s instead", new_path);

diff --git a/t/t6036-recursive-corner-cases.sh b/t/t6036-recursive-corner-cases.sh
index 6c2b2bfa6773d227ed4d6781a54f278201105331..a2e5c5c08fdacbc50e8d9e464665f0e9c1bcfccf 100755 (executable)
--- a/t/t6036-recursive-corner-cases.sh
+++ b/t/t6036-recursive-corner-cases.sh
@@ -120,7 +120,7 @@ test_expect_success 'setup criss-cross + rename merges with basic modification'
        git tag R2
 '
 
-test_expect_failure 'merge criss-cross + rename merges with basic modification' '
+test_expect_success 'merge criss-cross + rename merges with basic modification' '
        git reset --hard &&
        git checkout L2^0 &&
 
@@ -202,7 +202,7 @@ test_expect_success 'setup differently handled merges of rename/add conflict' '
        git tag E
 '
 
-test_expect_failure 'git detects differently handled merges conflict' '
+test_expect_success 'git detects differently handled merges conflict' '
        git reset --hard &&
        git checkout D^0 &&