If the two paths 'dir/A/file' and 'dir/B/file' have identical content
and the parent directory is renamed, e.g. 'git mv dir other-dir', then
diffcore reports the following exact renames:
renamed:dir/B/file -> other-dir/A/file
renamed:dir/A/file -> other-dir/B/file
While technically not wrong, this is confusing not only for the user,
but also for git commands that make decisions based on rename
information, e.g. 'git log --follow other-dir/A/file' follows
'dir/B/file' past the rename.
This behavior is a side effect of commit v2.0.0-rc4~8^2~14
(diffcore-rename.c: simplify finding exact renames, 2013-11-14): the
hashmap storing sources returns entries from the same bucket, i.e.
sources matching the current destination, in LIFO order. Thus the
iteration first examines 'other-dir/A/file' and 'dir/B/file' and, upon
finding identical content and basename, reports an exact rename.
Other hashmap users are apparently happy with the current iteration
order over the entries of a bucket. Changing the iteration order
would risk upsetting other hashmap users and would increase the memory
footprint of each bucket by a pointer to the tail element.
Fill the hashmap with source entries in reverse order to restore the
original exact rename detection behavior.
Reported-by: Bill Okara
Signed-off-by: SZEDER Gábor
---
Resend of the patch, with a slightly updated commit message, included
in
http://thread.gmane.org/gmane.comp.version-control.git/287281/focus=287570
Being embedded with scissors in an email without Junio among the
recipients on the day the first -rc was tagged... no wonder it flew
below the radar.
diffcore-rename.c | 6 --
t/t4001-diff-rename.sh | 11 +++
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/diffcore-rename.c b/diffcore-rename.c
index 3b3c1ed535e7..7f03eb5a0404 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -340,9 +340,11 @@ static int find_exact_renames(struct diff_options *options)
int i, renames = 0;
struct hashmap file_table;
- /* Add all sources to the hash table */
+ /* Add all sources to the hash table in reverse order, because
+* later on they will be retrieved in LIFO order.
+*/
hashmap_init(&file_table, NULL, rename_src_nr);
- for (i = 0; i < rename_src_nr; i++)
+ for (i = rename_src_nr-1; i >= 0; i--)
insert_file_table(&file_table, i, rename_src[i].p->one);
/* Walk the destinations and find best source match */
diff --git a/t/t4001-diff-rename.sh b/t/t4001-diff-rename.sh
index 2f327b749588..ed90c6c6f984 100755
--- a/t/t4001-diff-rename.sh
+++ b/t/t4001-diff-rename.sh
@@ -77,6 +77,17 @@ test_expect_success 'favour same basenames even with minor
differences' '
git show HEAD:path1 | sed "s/15/16/" > subdir/path1 &&
git status | test_i18ngrep "renamed: .*path1 -> subdir/path1"'
+test_expect_success 'two files with same basename and same content' '
+ git reset --hard &&
+ mkdir -p dir/A dir/B &&
+ cp path1 dir/A/file &&
+ cp path1 dir/B/file &&
+ git add dir &&
+ git commit -m 2 &&
+ git mv dir other-dir &&
+ git status | test_i18ngrep "renamed: .*dir/A/file -> other-dir/A/file"
+'
+
test_expect_success 'setup for many rename source candidates' '
git reset --hard &&
for i in 0 1 2 3 4 5 6 7 8 9;
--
2.8.0.46.gb821760
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