contrib/subtree: fix "subtree split" skipped-merge bug

'git subtree split' can incorrectly skip a merge even when both parents
act on the subtree, provided the merge results in a tree identical to
one of the parents. Fix by copying the merge if at least one parent is
non-identical, and the non-identical parent is not an ancestor of the
identical parent.

Also, add a test case which checks that a descendant remains a
descendent on the subtree in this case.

Signed-off-by: Dave Ware <davidw@realtimegenomics.com>
Reviewed-by: David A. Greene <greened@obbligato.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Dave Ware 2016-01-15 13:41:43 +13:00 committed by Junio C Hamano
parent 30fe9b2f9a
commit 933cfeb90b
2 changed files with 70 additions and 2 deletions

View File

@ -480,7 +480,15 @@ copy_or_skip()
fi
done
if [ -n "$identical" ]; then
copycommit=
if [ -n "$identical" ] && [ -n "$nonidentical" ]; then
extras=$(git rev-list --count $identical..$nonidentical)
if [ "$extras" -ne 0 ]; then
# we need to preserve history along the other branch
copycommit=1
fi
fi
if [ -n "$identical" ] && [ -z "$copycommit" ]; then
echo $identical
else
copy_commit $rev $tree "$p" || exit $?

View File

@ -1014,4 +1014,64 @@ test_expect_success 'push split to subproj' '
)
'
#
# This test covers 2 cases in subtree split copy_or_skip code
# 1) Merges where one parent is a superset of the changes of the other
# parent regarding changes to the subtree, in this case the merge
# commit should be copied
# 2) Merges where only one parent operate on the subtree, and the merge
# commit should be skipped
#
# (1) is checked by ensuring subtree_tip is a descendent of subtree_branch
# (2) should have a check added (not_a_subtree_change shouldn't be present
# on the produced subtree)
#
# Other related cases which are not tested (or currently handled correctly)
# - Case (1) where there are more than 2 parents, it will sometimes correctly copy
# the merge, and sometimes not
# - Merge commit where both parents have same tree as the merge, currently
# will always be skipped, even if they reached that state via different
# set of commits.
#
next_test
test_expect_success 'subtree descendant check' '
subtree_test_create_repo "$subtree_test_count" &&
test_create_commit "$subtree_test_count" folder_subtree/a &&
(
cd "$subtree_test_count" &&
git branch branch
) &&
test_create_commit "$subtree_test_count" folder_subtree/0 &&
test_create_commit "$subtree_test_count" folder_subtree/b &&
cherry=$(cd "$subtree_test_count"; git rev-parse HEAD) &&
(
cd "$subtree_test_count" &&
git checkout branch
) &&
test_create_commit "$subtree_test_count" commit_on_branch &&
(
cd "$subtree_test_count" &&
git cherry-pick $cherry &&
git checkout master &&
git merge -m "merge should be kept on subtree" branch &&
git branch no_subtree_work_branch
) &&
test_create_commit "$subtree_test_count" folder_subtree/d &&
(
cd "$subtree_test_count" &&
git checkout no_subtree_work_branch
) &&
test_create_commit "$subtree_test_count" not_a_subtree_change &&
(
cd "$subtree_test_count" &&
git checkout master &&
git merge -m "merge should be skipped on subtree" no_subtree_work_branch &&
git subtree split --prefix folder_subtree/ --branch subtree_tip master &&
git subtree split --prefix folder_subtree/ --branch subtree_branch branch &&
check_equal $(git rev-list --count subtree_tip..subtree_branch) 0
)
'
test_done