git rebase -i: warn about removed commits

Check if commits were removed (i.e. a line was deleted) and print
warnings or stop git rebase depending on the value of the
configuration variable rebase.missingCommitsCheck.

This patch gives the user the possibility to avoid silent loss of
information (losing a commit through deleting the line in this case)
if he wants.

Add the configuration variable rebase.missingCommitsCheck.
    - When unset or set to "ignore", no checking is done.
    - When set to "warn", the commits are checked, warnings are
      displayed but git rebase still proceeds.
    - When set to "error", the commits are checked, warnings are
      displayed and the rebase is stopped.
      (The user can then use 'git rebase --edit-todo' and
      'git rebase --continue', or 'git rebase --abort')

rebase.missingCommitsCheck defaults to "ignore".

Signed-off-by: Galan Rémi <remi.galan-alfonso@ensimag.grenoble-inp.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 66 insertions, 0 deletions

diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 3d059e5c09..cfa741018d 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -1120,4 +1120,70 @@ test_expect_success 'drop' '
 	test A = $(git cat-file commit HEAD^^ | sed -ne \$p)
 '
 
+cat >expect <<EOF
+Successfully rebased and updated refs/heads/missing-commit.
+EOF
+
+test_expect_success 'rebase -i respects rebase.missingCommitsCheck = ignore' '
+	test_config rebase.missingCommitsCheck ignore &&
+	rebase_setup_and_clean missing-commit &&
+	set_fake_editor &&
+	FAKE_LINES="1 2 3 4" \
+		git rebase -i --root 2>actual &&
+	test D = $(git cat-file commit HEAD | sed -ne \$p) &&
+	test_cmp expect actual
+'
+
+cat >expect <<EOF
+Warning: some commits may have been dropped accidentally.
+Dropped commits (newer to older):
+ - $(git rev-list --pretty=oneline --abbrev-commit -1 master)
+To avoid this message, use "drop" to explicitly remove a commit.
+
+Use 'git config rebase.missingCommitsCheck' to change the level of warnings.
+The possible behaviours are: ignore, warn, error.
+
+Successfully rebased and updated refs/heads/missing-commit.
+EOF
+
+test_expect_success 'rebase -i respects rebase.missingCommitsCheck = warn' '
+	test_config rebase.missingCommitsCheck warn &&
+	rebase_setup_and_clean missing-commit &&
+	set_fake_editor &&
+	FAKE_LINES="1 2 3 4" \
+		git rebase -i --root 2>actual &&
+	test_cmp expect actual &&
+	test D = $(git cat-file commit HEAD | sed -ne \$p)
+'
+
+cat >expect <<EOF
+Warning: some commits may have been dropped accidentally.
+Dropped commits (newer to older):
+ - $(git rev-list --pretty=oneline --abbrev-commit -1 master)
+ - $(git rev-list --pretty=oneline --abbrev-commit -1 master~2)
+To avoid this message, use "drop" to explicitly remove a commit.
+
+Use 'git config rebase.missingCommitsCheck' to change the level of warnings.
+The possible behaviours are: ignore, warn, error.
+
+You can fix this with 'git rebase --edit-todo'.
+Or you can abort the rebase with 'git rebase --abort'.
+EOF
+
+test_expect_success 'rebase -i respects rebase.missingCommitsCheck = error' '
+	test_config rebase.missingCommitsCheck error &&
+	rebase_setup_and_clean missing-commit &&
+	set_fake_editor &&
+	test_must_fail env FAKE_LINES="1 2 4" \
+		git rebase -i --root 2>actual &&
+	test_cmp expect actual &&
+	cp .git/rebase-merge/git-rebase-todo.backup \
+		.git/rebase-merge/git-rebase-todo &&
+	FAKE_LINES="1 2 drop 3 4 drop 5" \
+		git rebase --edit-todo &&
+	git rebase --continue &&
+	test D = $(git cat-file commit HEAD | sed -ne \$p) &&
+	test B = $(git cat-file commit HEAD^ | sed -ne \$p)
+'
+
 test_done