[PATCH v3 5/5] merge-ort: fix issue with dual rename and add/add conflict
- From
Elijah Newren via GitGitGadget <gitgitgadget@gmail.com>
- Date
- Jul 1, 2022, 05:23 UTC
- Message-ID
- <121761e26e2468d77910a7bee2e1f18776995c68.1656653000.git.gitgitgadget@gmail.com>
- In-Reply-To
- <pull.1268.v3.git.1656653000.gitgitgadget@gmail.com>
From: Elijah Newren <newren@gmail.com>
There is code in both merge-recursive and merge-ort for avoiding doubly transitive renames (i.e. one side renames directory A/ -> B/, and the other side renames directory B/ -> C/), because this combination would otherwise make a mess for new files added to A/ on the first side and wondering which directory they end up in -- especially if there were even more renames such as the first side renaming C/ -> D/. In such cases, it just turns "off" directory rename detection for the higher order transitive cases.
The testcases added in t6423 a couple commits ago are slightly different but similar in principle. They involve a similar case of paired renaming but instead of A/ -> B/ and B/ -> C/, the second side renames a leading directory of B/ to C/. And both sides add a new file somewhere under the directory that the other side will rename. While the new files added start within different directories and thus could logically end up within different directories, it is weird for a file on one side to end up where the other one started and not move along with it. So, let's just turn off directory rename detection in this case as well.
Another way to look at this is that if the source name involved in a directory rename on one side is the target name of a directory rename operation for a file from the other side, then we avoid the doubly transitive rename. (More concretely, if a directory rename on side D wants to rename a file on side E from OLD_NAME -> NEW_NAME, and side D already had a file named NEW_NAME, and a directory rename on side E wants to rename side D's NEW_NAME -> NEWER_NAME, then we turn off the directory rename detection for NEW_NAME to prevent the NEW_NAME -> NEWER_NAME rename, and instead end up with an add/add conflict on NEW_NAME.)
Signed-off-by: Elijah Newren <newren@gmail.com> --- merge-ort.c | 8 +++++++- t/t6423-merge-rename-directories.sh | 4 ++-- 2 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/merge-ort.c b/merge-ort.c index b496f0e3803..daa0e4496f8 100644 --- a/merge-ort.c +++ b/merge-ort.c @@ -2292,10 +2292,16 @@ static char *check_for_directory_rename(struct merge_options *opt, struct strmap_entry *rename_info; struct strmap_entry *otherinfo; const char *new_dir; + int other_side = 3 - side_index; - /* Cases where we don't have a directory rename for this path */ + /* + * Cases where we don't have or don't want a directory rename for + * this path. + */ if (strmap_empty(dir_renames)) return NULL; + if (strmap_get(&collisions[other_side], path)) + return NULL; rename_info = check_dir_renamed(path, dir_renames); if (!rename_info) return NULL; diff --git a/t/t6423-merge-rename-directories.sh b/t/t6423-merge-rename-directories.sh index ed5586de28c..99baf77cbfd 100755 --- a/t/t6423-merge-rename-directories.sh +++ b/t/t6423-merge-rename-directories.sh @@ -5250,7 +5250,7 @@ test_setup_12l () { ) } -test_expect_merge_algorithm failure failure '12l (B into A): Rename into each other + add/add conflict' ' +test_expect_merge_algorithm failure success '12l (B into A): Rename into each other + add/add conflict' ' test_setup_12l BintoA && ( cd 12l_BintoA && @@ -5277,7 +5277,7 @@ test_expect_merge_algorithm failure failure '12l (B into A): Rename into each ot ) ' -test_expect_merge_algorithm failure failure '12l (A into B): Rename into each other + add/add conflict' ' +test_expect_merge_algorithm failure success '12l (A into B): Rename into each other + add/add conflict' ' test_setup_12l AintoB && ( cd 12l_AintoB &&
-- gitgitgadget