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>

Elijah Newren committed Sep 20, 2010 at 02:28 UTC 2a669c341a857f53d946dec762e6f22a54b12dd2

2 files changed +3 -2

merge-recursive.c

@@ -1061,6 +1061,7 @@ static int process_renames(struct merge_options *o,

1061 mfi.sha,

1062 mfi.mode,

1063 ren1_dst);

1064 + try_merge = 0;

1065 } else {

1066 new_path = unique_path(o, ren1_dst, branch2);

1067 output(o, 1, "Adding as %s instead", new_path);

t/t6036-recursive-corner-cases.sh

+2 -2

@@ -120,7 +120,7 @@ test_expect_success 'setup criss-cross + rename merges with basic modification'

120 git tag R2

121 '

122

123 -test_expect_failure 'merge criss-cross + rename merges with basic modification' '

123 +test_expect_success 'merge criss-cross + rename merges with basic modification' '

124 git reset --hard &&

125 git checkout L2^0 &&

126

@@ -202,7 +202,7 @@ test_expect_success 'setup differently handled merges of rename/add conflict' '

202 git tag E

203 '

204

205 -test_expect_failure 'git detects differently handled merges conflict' '

205 +test_expect_success 'git detects differently handled merges conflict' '

206 git reset --hard &&

207 git checkout D^0 &&

208