Subject: [PATCH RESEND] branch: allow deleting dangling branches with --force

From: René Scharfe <[email-masked]>
Date: Wed, 25 Aug 2021 22:43:38 +0200

git branch only allows deleting branches that point to valid commits.
Skip that check if --force is given, as the caller is indicating with
it that they know what they are doing and accept the consequences.
This allows deleting dangling branches, which previously had to be
reset to a valid start-point using --force first.

Signed-off-by: René Scharfe <[email-masked]>
---
Original submission:
http://public-inbox.org/git/[email-masked]/

 Documentation/git-branch.txt | 3 ++-
 builtin/branch.c             | 2 +-
 t/t3200-branch.sh            | 7 +++++++
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-branch.txt b/Documentation/git-branch.txt
index 94dc9a54f2..5449767121 100644
--- a/Documentation/git-branch.txt
+++ b/Documentation/git-branch.txt
@@ -118,7 +118,8 @@ OPTIONS
 	Reset <branchname> to <startpoint>, even if <branchname> exists
 	already. Without `-f`, 'git branch' refuses to change an existing branch.
 	In combination with `-d` (or `--delete`), allow deleting the
-	branch irrespective of its merged status. In combination with
+	branch irrespective of its merged status, or whether it even
+	points to a valid commit. In combination with
 	`-m` (or `--move`), allow renaming the branch even if the new
 	branch name already exists, the same applies for `-c` (or `--copy`).

diff --git a/builtin/branch.c b/builtin/branch.c
index b23b1d1752..03c7b7253a 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -168,7 +168,7 @@ static int check_branch_commit(const char *branchname, const char *refname,
 			       int kinds, int force)
 {
 	struct commit *rev = lookup_commit_reference(the_repository, oid);
-	if (!rev) {
+	if (!force && !rev) {
 		error(_("Couldn't look up commit object for '%s'"), refname);
 		return -1;
 	}
diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index cc4b10236e..ec61a10c29 100755
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -1272,6 +1272,13 @@ test_expect_success 'attempt to delete a branch merged to its base' '
 	test_must_fail git branch -d my10
 '

+test_expect_success 'branch --delete --force removes dangling branch' '
+	test_when_finished "rm -f .git/refs/heads/dangling" &&
+	echo $ZERO_OID >.git/refs/heads/dangling &&
+	git branch --delete --force dangling &&
+	test_path_is_missing .git/refs/heads/dangling
+'
+
 test_expect_success 'use --edit-description' '
 	write_script editor <<-\EOF &&
 		echo "New contents" >"$1"
--
2.32.0