Hi Colin
Thanks for working on this. I'm not particularly familiar with
git-subtree but as far as I can see this version looks good.
Thanks
Phillip
On 10/09/2025 04:11, Colin Stagner wrote:
98ba49ccc2 (subtree: fix split processing with multiple subtrees
present, 2023-12-01) increases the performance of
git subtree split --prefix=subA
by ignoring subtree merges which are outside of `subA/`. It also
introduces a regression. Subtree merges that should be retained
are incorrectly ignored if they:
1. are nested under `subA/`; and
2. are merged with `--squash`.
For example, a subtree merged like:
git subtree merge --squash --prefix=subA/subB "$rev"
# ^^^^^^^^ ^^^^
is erroneously ignored during a split of `subA`. This causes
missing tree files and different commit hashes starting in
git v2.44.0-rc0.
The method:
should_ignore_subtree_split_commit REV
should test only a single commit REV, but the combination of
git log -1 --grep=...
actually searches all *parent* commits until a `--grep` match is
discovered.
Rewrite this method to test only one REV at a time. Extract commit
information with a single `git` call as opposed to three. The
`test` conditions for rejecting a commit remain unchanged.
Unit tests now cover nested subtrees.
Signed-off-by: Colin Stagner <ask+git@xxxxxxxxxxx>
---
Notes:
This bugfix patch is intended for maint-2.44 and up.
contrib/subtree/git-subtree.sh | 36 +++++++++++----
contrib/subtree/t/t7900-subtree.sh | 71 ++++++++++++++++++++++++++++++
2 files changed, 99 insertions(+), 8 deletions(-)
diff --git a/contrib/subtree/git-subtree.sh b/contrib/subtree/git-subtree.sh
index 5dab3f506c..ad9b9b0191 100755
--- a/contrib/subtree/git-subtree.sh
+++ b/contrib/subtree/git-subtree.sh
@@ -783,24 +783,44 @@ ensure_clean () {
# Usage: ensure_valid_ref_format REF
ensure_valid_ref_format () {
assert test $# = 1
git check-ref-format "refs/heads/$1" ||
die "fatal: '$1' does not look like a ref"
}
-# Usage: check if a commit from another subtree should be
+# Usage: should_ignore_subtree_split_commit REV
+#
+# Check if REV is a commit from another subtree and should be
# ignored from processing for splits
should_ignore_subtree_split_commit () {
assert test $# = 1
- local rev="$1"
+
+ git show \
+ --no-patch \
+ --no-show-signature \
+ --format='%(trailers:key=git-subtree-dir,key=git-subtree-mainline)' \
+ "$1" |
+ (
+ have_mainline=
+ subtree_dir=
+
+ while read -r trailer val
+ do
+ case "$trailer" in
+ git-subtree-dir:)
+ subtree_dir="${val%/}" ;;
+ git-subtree-mainline:)
+ have_mainline=y ;;
+ esac
+ done
+
- if test -n "$(git log -1 --grep="git-subtree-dir:" $rev)"
+ if test -n "${subtree_dir}" &&
+ test -z "${have_mainline}" &&
+ test "${subtree_dir}" != "$arg_prefix"
then
- if test -z "$(git log -1 --grep="git-subtree-mainline:" $rev)" &&
- test -z "$(git log -1 --grep="git-subtree-dir: $arg_prefix$" $rev)"
- then
- return 0
- fi
+ return 0
fi
return 1
+ )
}
# Usage: process_split_commit REV PARENTS
diff --git a/contrib/subtree/t/t7900-subtree.sh b/contrib/subtree/t/t7900-subtree.sh
index ca4df5be83..25be40e12b 100755
--- a/contrib/subtree/t/t7900-subtree.sh
+++ b/contrib/subtree/t/t7900-subtree.sh
@@ -9,6 +9,9 @@ This test verifies the basic operation of the add, merge, split, pull,
and push subcommands of git subtree.
'
+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+
TEST_DIRECTORY=$(pwd)/../../../t
. "$TEST_DIRECTORY"/test-lib.sh
@@ -67,6 +70,33 @@ test_create_pre2_32_repo () {
git -C "$1-clone" replace HEAD^2 $new_commit
}
+# test_create_subtree_add REPO ORPHAN PREFIX FILENAME ...
+#
+# Create a simple subtree on a new branch named ORPHAN in REPO.
+# The subtree is then merged into the current branch of REPO,
+# under PREFIX. The generated subtree has has one commit
+# with subject and tag FILENAME with a single file "FILENAME.t"
+#
+# When this method returns:
+# - the current branch of REPO will have file PREFIX/FILENAME.t
+# - REPO will have a branch named ORPHAN with subtree history
+#
+# additional arguments are forwarded to "subtree add"
+test_create_subtree_add () {
+ (
+ cd "$1" &&
+ orphan="$2" &&
+ prefix="$3" &&
+ filename="$4" &&
+ shift 4 &&
+ last="$(git branch --show-current)" &&
+ git switch --orphan "$orphan" &&
+ test_commit "$filename" &&
+ git checkout "$last" &&
+ git subtree add --prefix="$prefix" "$@" "$orphan"
+ )
+}
+
test_expect_success 'shows short help text for -h' '
test_expect_code 129 git subtree -h >out 2>err &&
test_must_be_empty err &&
@@ -425,6 +455,47 @@ test_expect_success 'split with multiple subtrees' '
--squash --rejoin -d -m "Sub B Split 1" 2>&1 | grep -w "\[1\]")" = ""
'
+# When subtree split-ing a directory that has other subtree
+# *merges* underneath it, the split must include those subtrees.
+# This test creates a nested subtree, `subA/subB`, and tests
+# that the tree is correct after a subtree split of `subA/`.
+# The test covers:
+# - An initial `subtree add`; and
+# - A follow-up `subtree merge`
+# both with and without `--squashed`.
+for is_squashed in '' 'y'
+do
+ test_expect_success "split keeps nested ${is_squashed:+--squash }subtrees that are part of the split" '
+ subtree_test_create_repo "$test_count" &&
+ (
+ cd "$test_count" &&
+ mkdir subA &&
+ test_commit subA/file1 &&
+ test_create_subtree_add \
+ . mksubtree subA/subB file2 ${is_squashed:+--squash} &&
+ test_path_is_file subA/file1.t &&
+ test_path_is_file subA/subB/file2.t &&
+ git subtree split --prefix=subA --branch=bsplit &&
+ git checkout bsplit &&
+ test_path_is_file file1.t &&
+ test_path_is_file subB/file2.t &&
+ git checkout mksubtree &&
+ git branch -D bsplit &&
+ test_commit file3 &&
+ git checkout main &&
+ git subtree merge \
+ ${is_squashed:+--squash} \
+ --prefix=subA/subB mksubtree &&
+ test_path_is_file subA/subB/file3.t &&
+ git subtree split --prefix=subA --branch=bsplit &&
+ git checkout bsplit &&
+ test_path_is_file file1.t &&
+ test_path_is_file subB/file2.t &&
+ test_path_is_file subB/file3.t
+ )
+ '
+done
+
test_expect_success 'split sub dir/ with --rejoin from scratch' '
subtree_test_create_repo "$test_count" &&
test_create_commit "$test_count" main1 &&
base-commit: 09669c729af92144fde84e97d358759b5b42b555
