From 1bec4d1dfd68653c6590a0cf0bf12831810bc21e Mon Sep 17 00:00:00 2001
From: Derrick Stolee <derrickstolee@github.com>
Date: Tue, 19 Jul 2022 18:33:33 +0000
Subject: [PATCH 01/12] t2407: test bisect and rebase as black-boxes

The tests added by d2ba271aad0 (branch: check for bisects and rebases,
2022-06-14) modified hidden state to verify the branch_checked_out()
helper. While this indeed checks that the method implementation is _as
designed_, it doesn't show that it is _correct_. Specifically, if 'git
bisect' or 'git rebase' change their back-end for preserving refs, then
these tests do not demonstrate that drift as a bug in
branch_checked_out().

Modify the tests in t2407 to actually rely on a paused bisect or rebase.
This requires adding the !SANITIZE_LEAK prereq for tests using those
builtins. The logic is still tested for leaks in the final test which
does set up that back-end directly for an error state that should not be
possible using Git commands.

Reported-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 t/t2407-worktree-heads.sh | 57 +++++++++++++++++++++------------------
 1 file changed, 31 insertions(+), 26 deletions(-)

diff --git a/t/t2407-worktree-heads.sh b/t/t2407-worktree-heads.sh
index b6be42f74a..100ab286d5 100755
--- a/t/t2407-worktree-heads.sh
+++ b/t/t2407-worktree-heads.sh
@@ -7,13 +7,18 @@ TEST_PASSES_SANITIZE_LEAK=true
 
 test_expect_success 'setup' '
 	test_commit init &&
-	git branch -f fake-1 &&
-	git branch -f fake-2 &&
 
 	for i in 1 2 3 4
 	do
+		git checkout -b conflict-$i &&
+		echo "not I" >$i.t &&
+		git add $i.t &&
+		git commit -m "will conflict" &&
+
+		git checkout - &&
 		test_commit $i &&
 		git branch wt-$i &&
+		git branch fake-$i &&
 		git worktree add wt-$i wt-$i || return 1
 	done &&
 
@@ -44,26 +49,26 @@ test_expect_success 'refuse to overwrite: checked out in worktree' '
 	done
 '
 
-test_expect_success 'refuse to overwrite: worktree in bisect' '
-	test_when_finished rm -rf .git/worktrees/wt-*/BISECT_* &&
+test_expect_success !SANITIZE_LEAK 'refuse to overwrite: worktree in bisect' '
+	test_when_finished git -C wt-4 bisect reset &&
 
-	touch .git/worktrees/wt-4/BISECT_LOG &&
-	echo refs/heads/fake-2 >.git/worktrees/wt-4/BISECT_START &&
+	# Set up a bisect so HEAD no longer points to wt-4.
+	git -C wt-4 bisect start &&
+	git -C wt-4 bisect bad wt-4 &&
+	git -C wt-4 bisect good wt-1 &&
 
-	test_must_fail git branch -f fake-2 HEAD 2>err &&
-	grep "cannot force update the branch '\''fake-2'\'' checked out at.*wt-4" err
+	test_must_fail git branch -f wt-4 HEAD 2>err &&
+	grep "cannot force update the branch '\''wt-4'\'' checked out at.*wt-4" err
 '
 
-test_expect_success 'refuse to overwrite: worktree in rebase' '
-	test_when_finished rm -rf .git/worktrees/wt-*/rebase-merge &&
+test_expect_success !SANITIZE_LEAK 'refuse to overwrite: worktree in rebase' '
+	test_when_finished git -C wt-2 rebase --abort &&
 
-	mkdir -p .git/worktrees/wt-3/rebase-merge &&
-	touch .git/worktrees/wt-3/rebase-merge/interactive &&
-	echo refs/heads/fake-1 >.git/worktrees/wt-3/rebase-merge/head-name &&
-	echo refs/heads/fake-2 >.git/worktrees/wt-3/rebase-merge/onto &&
+	# This will fail part-way through due to a conflict.
+	test_must_fail git -C wt-2 rebase conflict-2 &&
 
-	test_must_fail git branch -f fake-1 HEAD 2>err &&
-	grep "cannot force update the branch '\''fake-1'\'' checked out at.*wt-3" err
+	test_must_fail git branch -f wt-2 HEAD 2>err &&
+	grep "cannot force update the branch '\''wt-2'\'' checked out at.*wt-2" err
 '
 
 test_expect_success !SANITIZE_LEAK 'refuse to fetch over ref: checked out' '
@@ -77,24 +82,24 @@ test_expect_success !SANITIZE_LEAK 'refuse to fetch over ref: checked out' '
 '
 
 test_expect_success !SANITIZE_LEAK 'refuse to fetch over ref: worktree in bisect' '
-	test_when_finished rm -rf .git/worktrees/wt-*/BISECT_* &&
+	test_when_finished git -C wt-4 bisect reset &&
 
-	touch .git/worktrees/wt-4/BISECT_LOG &&
-	echo refs/heads/fake-2 >.git/worktrees/wt-4/BISECT_START &&
+	# Set up a bisect so HEAD no longer points to wt-4.
+	git -C wt-4 bisect start &&
+	git -C wt-4 bisect bad wt-4 &&
+	git -C wt-4 bisect good wt-1 &&
 
-	test_must_fail git fetch server +refs/heads/fake-2:refs/heads/fake-2 2>err &&
+	test_must_fail git fetch server +refs/heads/wt-4:refs/heads/wt-4 2>err &&
 	grep "refusing to fetch into branch" err
 '
 
 test_expect_success !SANITIZE_LEAK 'refuse to fetch over ref: worktree in rebase' '
-	test_when_finished rm -rf .git/worktrees/wt-*/rebase-merge &&
+	test_when_finished git -C wt-3 rebase --abort &&
 
-	mkdir -p .git/worktrees/wt-4/rebase-merge &&
-	touch .git/worktrees/wt-4/rebase-merge/interactive &&
-	echo refs/heads/fake-1 >.git/worktrees/wt-4/rebase-merge/head-name &&
-	echo refs/heads/fake-2 >.git/worktrees/wt-4/rebase-merge/onto &&
+	# This will fail part-way through due to a conflict.
+	test_must_fail git -C wt-3 rebase conflict-3 &&
 
-	test_must_fail git fetch server +refs/heads/fake-1:refs/heads/fake-1 2>err &&
+	test_must_fail git fetch server +refs/heads/wt-3:refs/heads/wt-3 2>err &&
 	grep "refusing to fetch into branch" err
 '
 

From 18ea59582778bd0b80fc643bc4e2981275d2300d Mon Sep 17 00:00:00 2001
From: Derrick Stolee <derrickstolee@github.com>
Date: Tue, 19 Jul 2022 18:33:34 +0000
Subject: [PATCH 02/12] t2407: test branches currently using apply backend

The tests in t2407 that verify the branch_checked_out() helper in the
case of bisects and rebases were added by 9347303db89 (branch: check for
bisects and rebases, 2022-06-08). However, that commit failed to check
for rebases that are using the 'apply' backend.

Add a test that checks the apply backend. The implementation was already
correct here, but it is good to have regression tests before modifying
the implementation further.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 t/t2407-worktree-heads.sh | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/t/t2407-worktree-heads.sh b/t/t2407-worktree-heads.sh
index 100ab286d5..a67ce5fb00 100755
--- a/t/t2407-worktree-heads.sh
+++ b/t/t2407-worktree-heads.sh
@@ -61,7 +61,17 @@ test_expect_success !SANITIZE_LEAK 'refuse to overwrite: worktree in bisect' '
 	grep "cannot force update the branch '\''wt-4'\'' checked out at.*wt-4" err
 '
 
-test_expect_success !SANITIZE_LEAK 'refuse to overwrite: worktree in rebase' '
+test_expect_success !SANITIZE_LEAK 'refuse to overwrite: worktree in rebase (apply)' '
+	test_when_finished git -C wt-2 rebase --abort &&
+
+	# This will fail part-way through due to a conflict.
+	test_must_fail git -C wt-2 rebase --apply conflict-2 &&
+
+	test_must_fail git branch -f wt-2 HEAD 2>err &&
+	grep "cannot force update the branch '\''wt-2'\'' checked out at.*wt-2" err
+'
+
+test_expect_success !SANITIZE_LEAK 'refuse to overwrite: worktree in rebase (merge)' '
 	test_when_finished git -C wt-2 rebase --abort &&
 
 	# This will fail part-way through due to a conflict.

From aa7f2fd150e7817de6c781dc5911d6c85f334324 Mon Sep 17 00:00:00 2001
From: Derrick Stolee <derrickstolee@github.com>
Date: Tue, 19 Jul 2022 18:33:35 +0000
Subject: [PATCH 03/12] branch: consider refs under 'update-refs'

The branch_checked_out() helper helps commands like 'git branch' and
'git fetch' from overwriting refs that are currently checked out in
other worktrees.

A future update to 'git rebase' will introduce a new '--update-refs'
option which will update the local refs that point to commits that are
being rebased. To avoid collisions as the rebase completes, we want to
make the future data store for these refs to be considered by
branch_checked_out().

The data store is a plaintext file inside the 'rebase-merge' directory
for that worktree. The file lists refnames followed by two OIDs, each on
separate lines. The OIDs will be used to store the original values of
the refs and the to-be-written values as the rebase progresses, but can
be ignored at the moment.

Create a new sequencer_get_update_refs_state() method that parses this
file and populates a struct string_list with the ref-OID pairs. We can
then use this list to add to the current_checked_out_branches strmap
used by branch_checked_out().

To properly navigate to the rebase directory for a given worktree,
extract the static strbuf_worktree_gitdir() method to a public API
method.

We can test that this works without having Git write this file by
artificially creating one in our test script, at least until 'git rebase
--update-refs' is implemented and we can use it directly.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 branch.c                  | 13 +++++++
 sequencer.c               | 74 +++++++++++++++++++++++++++++++++++++++
 sequencer.h               |  9 +++++
 t/t2407-worktree-heads.sh | 23 ++++++++++++
 4 files changed, 119 insertions(+)

diff --git a/branch.c b/branch.c
index 6dbd933288..d182756827 100644
--- a/branch.c
+++ b/branch.c
@@ -388,6 +388,7 @@ static void prepare_checked_out_branches(void)
 		char *old;
 		struct wt_status_state state = { 0 };
 		struct worktree *wt = worktrees[i++];
+		struct string_list update_refs = STRING_LIST_INIT_DUP;
 
 		if (wt->is_bare)
 			continue;
@@ -423,6 +424,18 @@ static void prepare_checked_out_branches(void)
 			strbuf_release(&ref);
 		}
 		wt_status_state_free_buffers(&state);
+
+		if (!sequencer_get_update_refs_state(get_worktree_git_dir(wt),
+						     &update_refs)) {
+			struct string_list_item *item;
+			for_each_string_list_item(item, &update_refs) {
+				old = strmap_put(&current_checked_out_branches,
+						 item->string,
+						 xstrdup(wt->path));
+				free(old);
+			}
+			string_list_clear(&update_refs, 1);
+		}
 	}
 
 	free_worktrees(worktrees);
diff --git a/sequencer.c b/sequencer.c
index 61a8e0020d..c4f3b4808e 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -147,6 +147,20 @@ static GIT_PATH_FUNC(rebase_path_squash_onto, "rebase-merge/squash-onto")
  */
 static GIT_PATH_FUNC(rebase_path_refs_to_delete, "rebase-merge/refs-to-delete")
 
+/*
+ * The update-refs file stores a list of refs that will be updated at the end
+ * of the rebase sequence. The 'update-ref <ref>' commands in the todo file
+ * update the OIDs for the refs in this file, but the refs are not updated
+ * until the end of the rebase sequence.
+ *
+ * rebase_path_update_refs() returns the path to this file for a given
+ * worktree directory. For the current worktree, pass the_repository->gitdir.
+ */
+static char *rebase_path_update_refs(const char *wt_git_dir)
+{
+	return xstrfmt("%s/rebase-merge/update-refs", wt_git_dir);
+}
+
 /*
  * The following files are written by git-rebase just after parsing the
  * command-line.
@@ -169,6 +183,15 @@ static GIT_PATH_FUNC(rebase_path_no_reschedule_failed_exec, "rebase-merge/no-res
 static GIT_PATH_FUNC(rebase_path_drop_redundant_commits, "rebase-merge/drop_redundant_commits")
 static GIT_PATH_FUNC(rebase_path_keep_redundant_commits, "rebase-merge/keep_redundant_commits")
 
+/**
+ * A 'struct update_refs_record' represents a value in the update-refs
+ * list. We use a string_list to map refs to these (before, after) pairs.
+ */
+struct update_ref_record {
+	struct object_id before;
+	struct object_id after;
+};
+
 static int git_sequencer_config(const char *k, const char *v, void *cb)
 {
 	struct replay_opts *opts = cb;
@@ -5936,3 +5959,54 @@ int sequencer_determine_whence(struct repository *r, enum commit_whence *whence)
 
 	return 0;
 }
+
+int sequencer_get_update_refs_state(const char *wt_dir,
+				    struct string_list *refs)
+{
+	int result = 0;
+	FILE *fp = NULL;
+	struct strbuf ref = STRBUF_INIT;
+	struct strbuf hash = STRBUF_INIT;
+	struct update_ref_record *rec = NULL;
+
+	char *path = rebase_path_update_refs(wt_dir);
+
+	fp = fopen(path, "r");
+	if (!fp)
+		goto cleanup;
+
+	while (strbuf_getline(&ref, fp) != EOF) {
+		struct string_list_item *item;
+
+		CALLOC_ARRAY(rec, 1);
+
+		if (strbuf_getline(&hash, fp) == EOF ||
+		    get_oid_hex(hash.buf, &rec->before)) {
+			warning(_("update-refs file at '%s' is invalid"),
+				  path);
+			result = -1;
+			goto cleanup;
+		}
+
+		if (strbuf_getline(&hash, fp) == EOF ||
+		    get_oid_hex(hash.buf, &rec->after)) {
+			warning(_("update-refs file at '%s' is invalid"),
+				  path);
+			result = -1;
+			goto cleanup;
+		}
+
+		item = string_list_insert(refs, ref.buf);
+		item->util = rec;
+		rec = NULL;
+	}
+
+cleanup:
+	if (fp)
+		fclose(fp);
+	free(path);
+	free(rec);
+	strbuf_release(&ref);
+	strbuf_release(&hash);
+	return result;
+}
diff --git a/sequencer.h b/sequencer.h
index 698599fe4e..8e38eb5ad7 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -233,4 +233,13 @@ void sequencer_post_commit_cleanup(struct repository *r, int verbose);
 int sequencer_get_last_command(struct repository* r,
 			       enum replay_action *action);
 int sequencer_determine_whence(struct repository *r, enum commit_whence *whence);
+
+/**
+ * Append the set of ref-OID pairs that are currently stored for the 'git
+ * rebase --update-refs' feature if such a rebase is currently happening.
+ *
+ * Localized to a worktree's git dir.
+ */
+int sequencer_get_update_refs_state(const char *wt_dir, struct string_list *refs);
+
 #endif /* SEQUENCER_H */
diff --git a/t/t2407-worktree-heads.sh b/t/t2407-worktree-heads.sh
index a67ce5fb00..97f5c87f8c 100755
--- a/t/t2407-worktree-heads.sh
+++ b/t/t2407-worktree-heads.sh
@@ -81,6 +81,29 @@ test_expect_success !SANITIZE_LEAK 'refuse to overwrite: worktree in rebase (mer
 	grep "cannot force update the branch '\''wt-2'\'' checked out at.*wt-2" err
 '
 
+test_expect_success 'refuse to overwrite: worktree in rebase with --update-refs' '
+	test_when_finished rm -rf .git/worktrees/wt-3/rebase-merge &&
+
+	mkdir -p .git/worktrees/wt-3/rebase-merge &&
+	touch .git/worktrees/wt-3/rebase-merge/interactive &&
+
+	cat >.git/worktrees/wt-3/rebase-merge/update-refs <<-EOF &&
+	refs/heads/fake-3
+	$(git rev-parse HEAD~1)
+	$(git rev-parse HEAD)
+	refs/heads/fake-4
+	$(git rev-parse HEAD)
+	$(git rev-parse HEAD)
+	EOF
+
+	for i in 3 4
+	do
+		test_must_fail git branch -f fake-$i HEAD 2>err &&
+		grep "cannot force update the branch '\''fake-$i'\'' checked out at.*wt-3" err ||
+			return 1
+	done
+'
+
 test_expect_success !SANITIZE_LEAK 'refuse to fetch over ref: checked out' '
 	test_must_fail git fetch server +refs/heads/wt-3:refs/heads/wt-3 2>err &&
 	grep "refusing to fetch into branch '\''refs/heads/wt-3'\''" err &&

From f57fd48d56864ed9a09d65cffe2c70b86ca7b652 Mon Sep 17 00:00:00 2001
From: Derrick Stolee <derrickstolee@github.com>
Date: Tue, 19 Jul 2022 18:33:36 +0000
Subject: [PATCH 04/12] rebase-interactive: update 'merge' description

The 'merge' command description for the todo list documentation in an
interactive rebase has multiple lines. The lines other than the first
one start with dots ('.') while the similar multi-line documentation for
'fixup' does not. This description only appears in the comment text of
the todo file during an interactive rebase.

The 'merge' command was documented when interactive rebase was first
ported to C in 145e05ac44b (rebase -i: rewrite append_todo_help() in C,
2018-08-10). These dots might have been carried over from the previous
shell implementation.

The 'fixup' command was documented more recently in 9e3cebd97cb (rebase
-i: add fixup [-C | -c] command, 2021-01-29).

Looking at the output in an editor, my personal opinion is that the dots
are unnecessary and noisy. Remove them now before adding more commands
with multi-line documentation.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 rebase-interactive.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/rebase-interactive.c b/rebase-interactive.c
index 87649d0c01..22394224fa 100644
--- a/rebase-interactive.c
+++ b/rebase-interactive.c
@@ -54,9 +54,9 @@ void append_todo_help(int command_count,
 "l, label <label> = label current HEAD with a name\n"
 "t, reset <label> = reset HEAD to a label\n"
 "m, merge [-C <commit> | -c <commit>] <label> [# <oneline>]\n"
-".       create a merge commit using the original merge commit's\n"
-".       message (or the oneline, if no original merge commit was\n"
-".       specified); use -c <commit> to reword the commit message\n"
+"        create a merge commit using the original merge commit's\n"
+"        message (or the oneline, if no original merge commit was\n"
+"        specified); use -c <commit> to reword the commit message\n"
 "\n"
 "These lines can be re-ordered; they are executed from top to bottom.\n");
 	unsigned edit_todo = !(shortrevisions && shortonto);

From d7ce9a220196b995117252bb236baf135c9b704f Mon Sep 17 00:00:00 2001
From: Derrick Stolee <derrickstolee@github.com>
Date: Tue, 19 Jul 2022 18:33:37 +0000
Subject: [PATCH 05/12] sequencer: define array with enum values

The todo_command_info array defines which strings match with which
todo_command enum values. The array is defined in the same order as the
enum values, but if one changed without the other, then we would have
unexpected results.

Make it easier to see changes to the enum and this array by using the
enum values as the indices of the array.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 sequencer.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index c4f3b4808e..bcfd25c8c3 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -1712,20 +1712,20 @@ static struct {
 	char c;
 	const char *str;
 } todo_command_info[] = {
-	{ 'p', "pick" },
-	{ 0,   "revert" },
-	{ 'e', "edit" },
-	{ 'r', "reword" },
-	{ 'f', "fixup" },
-	{ 's', "squash" },
-	{ 'x', "exec" },
-	{ 'b', "break" },
-	{ 'l', "label" },
-	{ 't', "reset" },
-	{ 'm', "merge" },
-	{ 0,   "noop" },
-	{ 'd', "drop" },
-	{ 0,   NULL }
+	[TODO_PICK] = { 'p', "pick" },
+	[TODO_REVERT] = { 0,   "revert" },
+	[TODO_EDIT] = { 'e', "edit" },
+	[TODO_REWORD] = { 'r', "reword" },
+	[TODO_FIXUP] = { 'f', "fixup" },
+	[TODO_SQUASH] = { 's', "squash" },
+	[TODO_EXEC] = { 'x', "exec" },
+	[TODO_BREAK] = { 'b', "break" },
+	[TODO_LABEL] = { 'l', "label" },
+	[TODO_RESET] = { 't', "reset" },
+	[TODO_MERGE] = { 'm', "merge" },
+	[TODO_NOOP] = { 0,   "noop" },
+	[TODO_DROP] = { 'd', "drop" },
+	[TODO_COMMENT] = { 0,   NULL },
 };
 
 static const char *command_to_string(const enum todo_command command)

From a97d79163e16e2d3777ab4d86c8f006f260c2836 Mon Sep 17 00:00:00 2001
From: Derrick Stolee <derrickstolee@github.com>
Date: Tue, 19 Jul 2022 18:33:38 +0000
Subject: [PATCH 06/12] sequencer: add update-ref command

Add the boilerplate for an "update-ref" command in the sequencer. This
connects to the current no-op do_update_ref() which will be filled in
after more connections are created.

The syntax in the todo list will be "update-ref <ref-name>" to signal
that we should store the current commit as the value for updating
<ref-name> at the end of the rebase.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 rebase-interactive.c |  3 +++
 sequencer.c          | 14 +++++++++++++-
 sequencer.h          |  1 +
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/rebase-interactive.c b/rebase-interactive.c
index 22394224fa..1ff07647af 100644
--- a/rebase-interactive.c
+++ b/rebase-interactive.c
@@ -57,6 +57,9 @@ void append_todo_help(int command_count,
 "        create a merge commit using the original merge commit's\n"
 "        message (or the oneline, if no original merge commit was\n"
 "        specified); use -c <commit> to reword the commit message\n"
+"u, update-ref <ref> = track a placeholder for the <ref> to be updated\n"
+"                      to this position in the new commits. The <ref> is\n"
+"                      updated at the end of the rebase\n"
 "\n"
 "These lines can be re-ordered; they are executed from top to bottom.\n");
 	unsigned edit_todo = !(shortrevisions && shortonto);
diff --git a/sequencer.c b/sequencer.c
index bcfd25c8c3..cac18a708c 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -1723,6 +1723,7 @@ static struct {
 	[TODO_LABEL] = { 'l', "label" },
 	[TODO_RESET] = { 't', "reset" },
 	[TODO_MERGE] = { 'm', "merge" },
+	[TODO_UPDATE_REF] = { 'u', "update-ref" },
 	[TODO_NOOP] = { 0,   "noop" },
 	[TODO_DROP] = { 'd', "drop" },
 	[TODO_COMMENT] = { 0,   NULL },
@@ -2504,7 +2505,7 @@ static int parse_insn_line(struct repository *r, struct todo_item *item,
 			     command_to_string(item->command));
 
 	if (item->command == TODO_EXEC || item->command == TODO_LABEL ||
-	    item->command == TODO_RESET) {
+	    item->command == TODO_RESET || item->command == TODO_UPDATE_REF) {
 		item->commit = NULL;
 		item->arg_offset = bol - buf;
 		item->arg_len = (int)(eol - bol);
@@ -4104,6 +4105,11 @@ leave_merge:
 	return ret;
 }
 
+static int do_update_ref(struct repository *r, const char *ref_name)
+{
+	return 0;
+}
+
 static int is_final_fixup(struct todo_list *todo_list)
 {
 	int i = todo_list->current;
@@ -4479,6 +4485,12 @@ static int pick_commits(struct repository *r,
 				return error_with_patch(r, item->commit,
 							arg, item->arg_len,
 							opts, res, 0);
+		} else if (item->command == TODO_UPDATE_REF) {
+			struct strbuf ref = STRBUF_INIT;
+			strbuf_add(&ref, arg, item->arg_len);
+			if ((res = do_update_ref(r, ref.buf)))
+				reschedule = 1;
+			strbuf_release(&ref);
 		} else if (!is_noop(item->command))
 			return error(_("unknown command %d"), item->command);
 
diff --git a/sequencer.h b/sequencer.h
index 8e38eb5ad7..d87feae366 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -96,6 +96,7 @@ enum todo_command {
 	TODO_LABEL,
 	TODO_RESET,
 	TODO_MERGE,
+	TODO_UPDATE_REF,
 	/* commands that do nothing but are counted for reporting progress */
 	TODO_NOOP,
 	TODO_DROP,

From 900b50c242dfa6b47033cbb495d2fd9d06752ff1 Mon Sep 17 00:00:00 2001
From: Derrick Stolee <derrickstolee@github.com>
Date: Tue, 19 Jul 2022 18:33:39 +0000
Subject: [PATCH 07/12] rebase: add --update-refs option

When working on a large feature, it can be helpful to break that feature
into multiple smaller parts that become reviewed in sequence. During
development or during review, a change to one part of the feature could
affect multiple of these parts. An interactive rebase can help adjust
the multi-part "story" of the branch.

However, if there are branches tracking the different parts of the
feature, then rebasing the entire list of commits can create commits not
reachable from those "sub branches". It can take a manual step to update
those branches.

Add a new --update-refs option to 'git rebase -i' that adds 'update-ref
<ref>' steps to the todo file whenever a commit that is being rebased is
decorated with that <ref>. At the very end, the rebase process updates
all of the listed refs to the values stored during the rebase operation.

Be sure to iterate after any squashing or fixups are placed. Update the
branch only after those squashes and fixups are complete. This allows a
--fixup commit at the tip of the feature to apply correctly to the sub
branch, even if it is fixing up the most-recent commit in that part.

This change update the documentation and builtin to accept the
--update-refs option as well as updating the todo file with the
'update-ref' commands. Tests are added to ensure that these todo
commands are added in the correct locations.

This change does _not_ include the actual behavior of tracking the
updated refs and writing the new ref values at the end of the rebase
process. That is deferred to a later change.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-rebase.txt  |   7 +++
 builtin/rebase.c              |   5 ++
 sequencer.c                   | 107 ++++++++++++++++++++++++++++++++++
 sequencer.h                   |   1 +
 t/t2407-worktree-heads.sh     |  22 +++++++
 t/t3404-rebase-interactive.sh |  74 +++++++++++++++++++++++
 6 files changed, 216 insertions(+)

diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index 262fb01aec..dfd847d661 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -609,6 +609,12 @@ provided. Otherwise an explicit `--no-reschedule-failed-exec` at the
 start would be overridden by the presence of
 `rebase.rescheduleFailedExec=true` configuration.
 
+--update-refs::
+--no-update-refs::
+	Automatically force-update any branches that point to commits that
+	are being rebased. Any branches that are checked out in a worktree
+	are not updated in this way.
+
 INCOMPATIBLE OPTIONS
 --------------------
 
@@ -632,6 +638,7 @@ are incompatible with the following options:
  * --empty=
  * --reapply-cherry-picks
  * --edit-todo
+ * --update-refs
  * --root when used in combination with --onto
 
 In addition, the following pairs of options are incompatible:
diff --git a/builtin/rebase.c b/builtin/rebase.c
index 70aa7c842f..2497533e8f 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -102,6 +102,7 @@ struct rebase_options {
 	int reschedule_failed_exec;
 	int reapply_cherry_picks;
 	int fork_point;
+	int update_refs;
 };
 
 #define REBASE_OPTIONS_INIT {			  	\
@@ -298,6 +299,7 @@ static int do_interactive_rebase(struct rebase_options *opts, unsigned flags)
 		ret = complete_action(the_repository, &replay, flags,
 			shortrevisions, opts->onto_name, opts->onto,
 			&opts->orig_head, &commands, opts->autosquash,
+			opts->update_refs,
 			&todo_list);
 	}
 
@@ -1124,6 +1126,9 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 		OPT_BOOL(0, "autosquash", &options.autosquash,
 			 N_("move commits that begin with "
 			    "squash!/fixup! under -i")),
+		OPT_BOOL(0, "update-refs", &options.update_refs,
+			 N_("update branches that point to commits "
+			    "that are being rebased")),
 		{ OPTION_STRING, 'S', "gpg-sign", &gpg_sign, N_("key-id"),
 			N_("GPG-sign commits"),
 			PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
diff --git a/sequencer.c b/sequencer.c
index cac18a708c..92204a8c2e 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -35,6 +35,7 @@
 #include "commit-reach.h"
 #include "rebase-interactive.h"
 #include "reset.h"
+#include "branch.h"
 
 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
 
@@ -5673,10 +5674,113 @@ static int skip_unnecessary_picks(struct repository *r,
 	return 0;
 }
 
+struct todo_add_branch_context {
+	struct todo_item *items;
+	size_t items_nr;
+	size_t items_alloc;
+	struct strbuf *buf;
+	struct commit *commit;
+	struct string_list refs_to_oids;
+};
+
+static int add_decorations_to_list(const struct commit *commit,
+				   struct todo_add_branch_context *ctx)
+{
+	const struct name_decoration *decoration = get_name_decoration(&commit->object);
+
+	while (decoration) {
+		struct todo_item *item;
+		const char *path;
+		size_t base_offset = ctx->buf->len;
+
+		ALLOC_GROW(ctx->items,
+			ctx->items_nr + 1,
+			ctx->items_alloc);
+		item = &ctx->items[ctx->items_nr];
+		memset(item, 0, sizeof(*item));
+
+		/* If the branch is checked out, then leave a comment instead. */
+		if ((path = branch_checked_out(decoration->name))) {
+			item->command = TODO_COMMENT;
+			strbuf_addf(ctx->buf, "# Ref %s checked out at '%s'\n",
+				    decoration->name, path);
+		} else {
+			struct string_list_item *sti;
+			item->command = TODO_UPDATE_REF;
+			strbuf_addf(ctx->buf, "%s\n", decoration->name);
+
+			sti = string_list_insert(&ctx->refs_to_oids,
+						 decoration->name);
+			sti->util = oiddup(the_hash_algo->null_oid);
+		}
+
+		item->offset_in_buf = base_offset;
+		item->arg_offset = base_offset;
+		item->arg_len = ctx->buf->len - base_offset;
+		ctx->items_nr++;
+
+		decoration = decoration->next;
+	}
+
+	return 0;
+}
+
+/*
+ * For each 'pick' command, find out if the commit has a decoration in
+ * refs/heads/. If so, then add a 'label for-update-refs/' command.
+ */
+static int todo_list_add_update_ref_commands(struct todo_list *todo_list)
+{
+	int i;
+	static struct string_list decorate_refs_exclude = STRING_LIST_INIT_NODUP;
+	static struct string_list decorate_refs_exclude_config = STRING_LIST_INIT_NODUP;
+	static struct string_list decorate_refs_include = STRING_LIST_INIT_NODUP;
+	struct decoration_filter decoration_filter = {
+		.include_ref_pattern = &decorate_refs_include,
+		.exclude_ref_pattern = &decorate_refs_exclude,
+		.exclude_ref_config_pattern = &decorate_refs_exclude_config,
+	};
+	struct todo_add_branch_context ctx = {
+		.buf = &todo_list->buf,
+		.refs_to_oids = STRING_LIST_INIT_DUP,
+	};
+
+	ctx.items_alloc = 2 * todo_list->nr + 1;
+	ALLOC_ARRAY(ctx.items, ctx.items_alloc);
+
+	string_list_append(&decorate_refs_include, "refs/heads/");
+	load_ref_decorations(&decoration_filter, 0);
+
+	for (i = 0; i < todo_list->nr; ) {
+		struct todo_item *item = &todo_list->items[i];
+
+		/* insert ith item into new list */
+		ALLOC_GROW(ctx.items,
+			   ctx.items_nr + 1,
+			   ctx.items_alloc);
+
+		ctx.items[ctx.items_nr++] = todo_list->items[i++];
+
+		if (item->commit) {
+			ctx.commit = item->commit;
+			add_decorations_to_list(item->commit, &ctx);
+		}
+	}
+
+	string_list_clear(&ctx.refs_to_oids, 1);
+	free(todo_list->items);
+	todo_list->items = ctx.items;
+	todo_list->nr = ctx.items_nr;
+	todo_list->alloc = ctx.items_alloc;
+
+	return 0;
+}
+
 int complete_action(struct repository *r, struct replay_opts *opts, unsigned flags,
 		    const char *shortrevisions, const char *onto_name,
 		    struct commit *onto, const struct object_id *orig_head,
 		    struct string_list *commands, unsigned autosquash,
+		    unsigned update_refs,
 		    struct todo_list *todo_list)
 {
 	char shortonto[GIT_MAX_HEXSZ + 1];
@@ -5695,6 +5799,9 @@ int complete_action(struct repository *r, struct replay_opts *opts, unsigned fla
 		item->arg_len = item->arg_offset = item->flags = item->offset_in_buf = 0;
 	}
 
+	if (update_refs && todo_list_add_update_ref_commands(todo_list))
+		return -1;
+
 	if (autosquash && todo_list_rearrange_squash(todo_list))
 		return -1;
 
diff --git a/sequencer.h b/sequencer.h
index d87feae366..8216b62f47 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -168,6 +168,7 @@ int complete_action(struct repository *r, struct replay_opts *opts, unsigned fla
 		    const char *shortrevisions, const char *onto_name,
 		    struct commit *onto, const struct object_id *orig_head,
 		    struct string_list *commands, unsigned autosquash,
+		    unsigned update_refs,
 		    struct todo_list *todo_list);
 int todo_list_rearrange_squash(struct todo_list *todo_list);
 
diff --git a/t/t2407-worktree-heads.sh b/t/t2407-worktree-heads.sh
index 97f5c87f8c..8a03f14df8 100755
--- a/t/t2407-worktree-heads.sh
+++ b/t/t2407-worktree-heads.sh
@@ -164,4 +164,26 @@ test_expect_success 'refuse to overwrite when in error states' '
 	done
 '
 
+. "$TEST_DIRECTORY"/lib-rebase.sh
+
+test_expect_success !SANITIZE_LEAK 'refuse to overwrite during rebase with --update-refs' '
+	git commit --fixup HEAD~2 --allow-empty &&
+	(
+		set_cat_todo_editor &&
+		test_must_fail git rebase -i --update-refs HEAD~3 >todo &&
+		! grep "update-refs" todo
+	) &&
+	git branch -f allow-update HEAD~2 &&
+	(
+		set_cat_todo_editor &&
+		test_must_fail git rebase -i --update-refs HEAD~3 >todo &&
+		grep "update-ref refs/heads/allow-update" todo
+	)
+'
+
+# This must be the last test in this file
+test_expect_success '$EDITOR and friends are unchanged' '
+	test_editor_unchanged
+'
+
 test_done
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index f31afd4a54..75c0b90fae 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -1743,6 +1743,80 @@ test_expect_success 'ORIG_HEAD is updated correctly' '
 	test_cmp_rev ORIG_HEAD test-orig-head@{1}
 '
 
+test_expect_success '--update-refs adds label and update-ref commands' '
+	git checkout -b update-refs no-conflict-branch &&
+	git branch -f base HEAD~4 &&
+	git branch -f first HEAD~3 &&
+	git branch -f second HEAD~3 &&
+	git branch -f third HEAD~1 &&
+	git commit --allow-empty --fixup=third &&
+	git branch -f is-not-reordered &&
+	git commit --allow-empty --fixup=HEAD~4 &&
+	git branch -f shared-tip &&
+	(
+		set_cat_todo_editor &&
+
+		cat >expect <<-EOF &&
+		pick $(git log -1 --format=%h J) J
+		fixup $(git log -1 --format=%h update-refs) fixup! J # empty
+		update-ref refs/heads/second
+		update-ref refs/heads/first
+		pick $(git log -1 --format=%h K) K
+		pick $(git log -1 --format=%h L) L
+		fixup $(git log -1 --format=%h is-not-reordered) fixup! L # empty
+		update-ref refs/heads/third
+		pick $(git log -1 --format=%h M) M
+		update-ref refs/heads/no-conflict-branch
+		update-ref refs/heads/is-not-reordered
+		update-ref refs/heads/shared-tip
+		EOF
+
+		test_must_fail git rebase -i --autosquash --update-refs primary >todo &&
+		test_cmp expect todo
+	)
+'
+
+test_expect_success '--update-refs adds commands with --rebase-merges' '
+	git checkout -b update-refs-with-merge no-conflict-branch &&
+	git branch -f base HEAD~4 &&
+	git branch -f first HEAD~3 &&
+	git branch -f second HEAD~3 &&
+	git branch -f third HEAD~1 &&
+	git merge -m merge branch2 &&
+	git branch -f merge-branch &&
+	git commit --fixup=third --allow-empty &&
+	(
+		set_cat_todo_editor &&
+
+		cat >expect <<-EOF &&
+		label onto
+		reset onto
+		pick $(git log -1 --format=%h branch2~1) F
+		pick $(git log -1 --format=%h branch2) I
+		update-ref refs/heads/branch2
+		label merge
+		reset onto
+		pick $(git log -1 --format=%h refs/heads/second) J
+		update-ref refs/heads/second
+		update-ref refs/heads/first
+		pick $(git log -1 --format=%h refs/heads/third~1) K
+		pick $(git log -1 --format=%h refs/heads/third) L
+		fixup $(git log -1 --format=%h update-refs-with-merge) fixup! L # empty
+		update-ref refs/heads/third
+		pick $(git log -1 --format=%h HEAD~2) M
+		update-ref refs/heads/no-conflict-branch
+		merge -C $(git log -1 --format=%h HEAD~1) merge # merge
+		update-ref refs/heads/merge-branch
+		EOF
+
+		test_must_fail git rebase -i --autosquash \
+				   --rebase-merges=rebase-cousins \
+				   --update-refs primary >todo &&
+
+		test_cmp expect todo
+	)
+'
+
 # This must be the last test in this file
 test_expect_success '$EDITOR and friends are unchanged' '
 	test_editor_unchanged

From 89fc0b53fdb4ea2f9581ea728577f4d2a4947672 Mon Sep 17 00:00:00 2001
From: Derrick Stolee <derrickstolee@github.com>
Date: Tue, 19 Jul 2022 18:33:40 +0000
Subject: [PATCH 08/12] rebase: update refs from 'update-ref' commands

The previous change introduced the 'git rebase --update-refs' option
which added 'update-ref <ref>' commands to the todo list of an
interactive rebase.

Teach Git to record the HEAD position when reaching these 'update-ref'
commands. The ref/before/after triple is stored in the
$GIT_DIR/rebase-merge/update-refs file. A previous change parsed this
file to avoid having other processes updating the refs in that file
while the rebase is in progress.

Not only do we update the file when the sequencer reaches these
'update-ref' commands, we then update the refs themselves at the end of
the rebase sequence. If the rebase is aborted before this final step,
then the refs are not updated. The 'before' value is used to ensure that
we do not accidentally obliterate a ref that was updated concurrently
(say, by an older version of Git or a third-party tool).

Now that the 'git rebase --update-refs' command is implemented to write
to the update-refs file, we can remove the fake construction of the
update-refs file from a test in t2407-worktree-heads.sh.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 sequencer.c                   | 120 +++++++++++++++++++++++++++++++++-
 t/t2407-worktree-heads.sh     |  21 ++----
 t/t3404-rebase-interactive.sh |  17 +++++
 3 files changed, 140 insertions(+), 18 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index 92204a8c2e..98111e394d 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -36,6 +36,7 @@
 #include "rebase-interactive.h"
 #include "reset.h"
 #include "branch.h"
+#include "log-tree.h"
 
 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
 
@@ -193,6 +194,21 @@ struct update_ref_record {
 	struct object_id after;
 };
 
+static struct update_ref_record *init_update_ref_record(const char *ref)
+{
+	struct update_ref_record *rec;
+
+	CALLOC_ARRAY(rec, 1);
+
+	oidcpy(&rec->before, null_oid());
+	oidcpy(&rec->after, null_oid());
+
+	/* This may fail, but that's fine, we will keep the null OID. */
+	read_ref(ref, &rec->before);
+
+	return rec;
+}
+
 static int git_sequencer_config(const char *k, const char *v, void *cb)
 {
 	struct replay_opts *opts = cb;
@@ -4106,11 +4122,97 @@ leave_merge:
 	return ret;
 }
 
-static int do_update_ref(struct repository *r, const char *ref_name)
+static int write_update_refs_state(struct string_list *refs_to_oids)
 {
+	int result = 0;
+	struct lock_file lock = LOCK_INIT;
+	FILE *fp = NULL;
+	struct string_list_item *item;
+	char *path;
+
+	if (!refs_to_oids->nr)
+		return 0;
+
+	path = rebase_path_update_refs(the_repository->gitdir);
+
+	if (safe_create_leading_directories(path)) {
+		result = error(_("unable to create leading directories of %s"),
+			       path);
+		goto cleanup;
+	}
+
+	if (hold_lock_file_for_update(&lock, path, 0) < 0) {
+		result = error(_("another 'rebase' process appears to be running; "
+				 "'%s.lock' already exists"),
+			       path);
+		goto cleanup;
+	}
+
+	fp = fdopen_lock_file(&lock, "w");
+	if (!fp) {
+		result = error_errno(_("could not open '%s' for writing"), path);
+		rollback_lock_file(&lock);
+		goto cleanup;
+	}
+
+	for_each_string_list_item(item, refs_to_oids) {
+		struct update_ref_record *rec = item->util;
+		fprintf(fp, "%s\n%s\n%s\n", item->string,
+			oid_to_hex(&rec->before), oid_to_hex(&rec->after));
+	}
+
+	result = commit_lock_file(&lock);
+
+cleanup:
+	free(path);
+	return result;
+}
+
+static int do_update_ref(struct repository *r, const char *refname)
+{
+	struct string_list_item *item;
+	struct string_list list = STRING_LIST_INIT_DUP;
+
+	if (sequencer_get_update_refs_state(r->gitdir, &list))
+		return -1;
+
+	for_each_string_list_item(item, &list) {
+		if (!strcmp(item->string, refname)) {
+			struct update_ref_record *rec = item->util;
+			if (read_ref("HEAD", &rec->after))
+				return -1;
+			break;
+		}
+	}
+
+	write_update_refs_state(&list);
+	string_list_clear(&list, 1);
 	return 0;
 }
 
+static int do_update_refs(struct repository *r)
+{
+	int res = 0;
+	struct string_list_item *item;
+	struct string_list refs_to_oids = STRING_LIST_INIT_DUP;
+	struct ref_store *refs = get_main_ref_store(r);
+
+	if ((res = sequencer_get_update_refs_state(r->gitdir, &refs_to_oids)))
+		return res;
+
+	for_each_string_list_item(item, &refs_to_oids) {
+		struct update_ref_record *rec = item->util;
+
+		res |= refs_update_ref(refs, "rewritten during rebase",
+				       item->string,
+				       &rec->after, &rec->before,
+				       0, UPDATE_REFS_MSG_ON_ERR);
+	}
+
+	string_list_clear(&refs_to_oids, 1);
+	return res;
+}
+
 static int is_final_fixup(struct todo_list *todo_list)
 {
 	int i = todo_list->current;
@@ -4627,6 +4729,9 @@ cleanup_head_ref:
 
 		strbuf_release(&buf);
 		strbuf_release(&head_ref);
+
+		if (do_update_refs(r))
+			return -1;
 	}
 
 	/*
@@ -5711,7 +5816,7 @@ static int add_decorations_to_list(const struct commit *commit,
 
 			sti = string_list_insert(&ctx->refs_to_oids,
 						 decoration->name);
-			sti->util = oiddup(the_hash_algo->null_oid);
+			sti->util = init_update_ref_record(decoration->name);
 		}
 
 		item->offset_in_buf = base_offset;
@@ -5731,7 +5836,7 @@ static int add_decorations_to_list(const struct commit *commit,
  */
 static int todo_list_add_update_ref_commands(struct todo_list *todo_list)
 {
-	int i;
+	int i, res;
 	static struct string_list decorate_refs_exclude = STRING_LIST_INIT_NODUP;
 	static struct string_list decorate_refs_exclude_config = STRING_LIST_INIT_NODUP;
 	static struct string_list decorate_refs_include = STRING_LIST_INIT_NODUP;
@@ -5767,7 +5872,16 @@ static int todo_list_add_update_ref_commands(struct todo_list *todo_list)
 		}
 	}
 
+	res = write_update_refs_state(&ctx.refs_to_oids);
+
 	string_list_clear(&ctx.refs_to_oids, 1);
+
+	if (res) {
+		/* we failed, so clean up the new list. */
+		free(ctx.items);
+		return res;
+	}
+
 	free(todo_list->items);
 	todo_list->items = ctx.items;
 	todo_list->nr = ctx.items_nr;
diff --git a/t/t2407-worktree-heads.sh b/t/t2407-worktree-heads.sh
index 8a03f14df8..50815acd3e 100755
--- a/t/t2407-worktree-heads.sh
+++ b/t/t2407-worktree-heads.sh
@@ -81,25 +81,16 @@ test_expect_success !SANITIZE_LEAK 'refuse to overwrite: worktree in rebase (mer
 	grep "cannot force update the branch '\''wt-2'\'' checked out at.*wt-2" err
 '
 
-test_expect_success 'refuse to overwrite: worktree in rebase with --update-refs' '
-	test_when_finished rm -rf .git/worktrees/wt-3/rebase-merge &&
+test_expect_success !SANITIZE_LEAK 'refuse to overwrite: worktree in rebase with --update-refs' '
+	test_when_finished git -C wt-3 rebase --abort &&
 
-	mkdir -p .git/worktrees/wt-3/rebase-merge &&
-	touch .git/worktrees/wt-3/rebase-merge/interactive &&
-
-	cat >.git/worktrees/wt-3/rebase-merge/update-refs <<-EOF &&
-	refs/heads/fake-3
-	$(git rev-parse HEAD~1)
-	$(git rev-parse HEAD)
-	refs/heads/fake-4
-	$(git rev-parse HEAD)
-	$(git rev-parse HEAD)
-	EOF
+	git branch -f can-be-updated wt-3 &&
+	test_must_fail git -C wt-3 rebase --update-refs conflict-3 &&
 
 	for i in 3 4
 	do
-		test_must_fail git branch -f fake-$i HEAD 2>err &&
-		grep "cannot force update the branch '\''fake-$i'\'' checked out at.*wt-3" err ||
+		test_must_fail git branch -f can-be-updated HEAD 2>err &&
+		grep "cannot force update the branch '\''can-be-updated'\'' checked out at.*wt-3" err ||
 			return 1
 	done
 '
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 75c0b90fae..2fffcf5d5f 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -1817,6 +1817,23 @@ test_expect_success '--update-refs adds commands with --rebase-merges' '
 	)
 '
 
+test_expect_success '--update-refs updates refs correctly' '
+	git checkout -B update-refs no-conflict-branch &&
+	git branch -f base HEAD~4 &&
+	git branch -f first HEAD~3 &&
+	git branch -f second HEAD~3 &&
+	git branch -f third HEAD~1 &&
+	test_commit extra2 fileX &&
+	git commit --amend --fixup=L &&
+
+	git rebase -i --autosquash --update-refs primary &&
+
+	test_cmp_rev HEAD~3 refs/heads/first &&
+	test_cmp_rev HEAD~3 refs/heads/second &&
+	test_cmp_rev HEAD~1 refs/heads/third &&
+	test_cmp_rev HEAD refs/heads/no-conflict-branch
+'
+
 # This must be the last test in this file
 test_expect_success '$EDITOR and friends are unchanged' '
 	test_editor_unchanged

From b3b1a21d1a5df87e81fa8b53c6c3cf9760ca12d4 Mon Sep 17 00:00:00 2001
From: Derrick Stolee <derrickstolee@github.com>
Date: Tue, 19 Jul 2022 18:33:41 +0000
Subject: [PATCH 09/12] sequencer: rewrite update-refs as user edits todo list

An interactive rebase provides opportunities for the user to edit the
todo list. The --update-refs option initializes the list with some
'update-ref <ref>' steps, but the user could add these manually.
Further, the user could add or remove these steps during pauses in the
interactive rebase.

Add a new method, todo_list_filter_update_refs(), that scans a todo_list
and compares it to the stored update-refs file. There are two actions
that can happen at this point:

1. If a '<ref>/<before>/<after>' triple in the update-refs file does not
   have a matching 'update-ref <ref>' command in the todo-list _and_ the
   <after> value is the null OID, then remove that triple. Here, the
   user removed the 'update-ref <ref>' command before it was executed,
   since if it was executed then the <after> value would store the
   commit at that position.

2. If a 'update-ref <ref>' command in the todo-list does not have a
   matching '<ref>/<before>/<after>' triple in the update-refs file,
   then insert a new one. Store the <before> value to be the current
   OID pointed at by <ref>. This is handled inside of the
   init_update_ref_record() helper method.

We can test that this works by rewriting the todo-list several times in
the course of a rebase. Check that each ref is locked or unlocked for
updates after each todo-list update. We can also verify that the ref
update fails if a concurrent process updates one of the refs after the
rebase process records the "locked" ref location.

To help these tests, add a new 'set_replace_editor' helper that will
replace the todo-list with an exact file.

Reported-by: Phillip Wood <phillip.wood123@gmail.com>
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 rebase-interactive.c          |   6 ++
 sequencer.c                   |  96 +++++++++++++++++++++++
 sequencer.h                   |  12 +++
 t/lib-rebase.sh               |  15 ++++
 t/t3404-rebase-interactive.sh | 139 ++++++++++++++++++++++++++++++++++
 5 files changed, 268 insertions(+)

diff --git a/rebase-interactive.c b/rebase-interactive.c
index 1ff07647af..7407c59319 100644
--- a/rebase-interactive.c
+++ b/rebase-interactive.c
@@ -146,6 +146,12 @@ int edit_todo_list(struct repository *r, struct todo_list *todo_list,
 		return -4;
 	}
 
+	/*
+	 * See if branches need to be added or removed from the update-refs
+	 * file based on the new todo list.
+	 */
+	todo_list_filter_update_refs(r, new_todo);
+
 	return 0;
 }
 
diff --git a/sequencer.c b/sequencer.c
index 98111e394d..20ca7b4435 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4168,6 +4168,102 @@ cleanup:
 	return result;
 }
 
+/*
+ * Parse the update-refs file for the current rebase, then remove the
+ * refs that do not appear in the todo_list (and have not had updated
+ * values stored) and add refs that are in the todo_list but not
+ * represented in the update-refs file.
+ *
+ * If there are changes to the update-refs list, then write the new state
+ * to disk.
+ */
+void todo_list_filter_update_refs(struct repository *r,
+				  struct todo_list *todo_list)
+{
+	int i;
+	int updated = 0;
+	struct string_list update_refs = STRING_LIST_INIT_DUP;
+
+	sequencer_get_update_refs_state(r->gitdir, &update_refs);
+
+	/*
+	 * For each item in the update_refs list, if it has no updated
+	 * value and does not appear in the todo_list, then remove it
+	 * from the update_refs list.
+	 */
+	for (i = 0; i < update_refs.nr; i++) {
+		int j;
+		int found = 0;
+		const char *ref = update_refs.items[i].string;
+		size_t reflen = strlen(ref);
+		struct update_ref_record *rec = update_refs.items[i].util;
+
+		/* OID already stored as updated. */
+		if (!is_null_oid(&rec->after))
+			continue;
+
+		for (j = 0; !found && j < todo_list->total_nr; j++) {
+			struct todo_item *item = &todo_list->items[j];
+			const char *arg = todo_list->buf.buf + item->arg_offset;
+
+			if (item->command != TODO_UPDATE_REF)
+				continue;
+
+			if (item->arg_len != reflen ||
+			    strncmp(arg, ref, reflen))
+				continue;
+
+			found = 1;
+		}
+
+		if (!found) {
+			free(update_refs.items[i].string);
+			free(update_refs.items[i].util);
+
+			update_refs.nr--;
+			MOVE_ARRAY(update_refs.items + i, update_refs.items + i + 1, update_refs.nr - i);
+
+			updated = 1;
+			i--;
+		}
+	}
+
+	/*
+	 * For each todo_item, check if its ref is in the update_refs list.
+	 * If not, then add it as an un-updated ref.
+	 */
+	for (i = 0; i < todo_list->total_nr; i++) {
+		struct todo_item *item = &todo_list->items[i];
+		const char *arg = todo_list->buf.buf + item->arg_offset;
+		int j, found = 0;
+
+		if (item->command != TODO_UPDATE_REF)
+			continue;
+
+		for (j = 0; !found && j < update_refs.nr; j++) {
+			const char *ref = update_refs.items[j].string;
+
+			found = strlen(ref) == item->arg_len &&
+				!strncmp(ref, arg, item->arg_len);
+		}
+
+		if (!found) {
+			struct string_list_item *inserted;
+			struct strbuf argref = STRBUF_INIT;
+
+			strbuf_add(&argref, arg, item->arg_len);
+			inserted = string_list_insert(&update_refs, argref.buf);
+			inserted->util = init_update_ref_record(argref.buf);
+			strbuf_release(&argref);
+			updated = 1;
+		}
+	}
+
+	if (updated)
+		write_update_refs_state(&update_refs);
+	string_list_clear(&update_refs, 1);
+}
+
 static int do_update_ref(struct repository *r, const char *refname)
 {
 	struct string_list_item *item;
diff --git a/sequencer.h b/sequencer.h
index 8216b62f47..563fe59933 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -133,6 +133,18 @@ void todo_list_release(struct todo_list *todo_list);
 const char *todo_item_get_arg(struct todo_list *todo_list,
 			      struct todo_item *item);
 
+/*
+ * Parse the update-refs file for the current rebase, then remove the
+ * refs that do not appear in the todo_list (and have not had updated
+ * values stored) and add refs that are in the todo_list but not
+ * represented in the update-refs file.
+ *
+ * If there are changes to the update-refs list, then write the new state
+ * to disk.
+ */
+void todo_list_filter_update_refs(struct repository *r,
+				  struct todo_list *todo_list);
+
 /* Call this to setup defaults before parsing command line options */
 void sequencer_init_config(struct replay_opts *opts);
 int sequencer_pick_revisions(struct repository *repo,
diff --git a/t/lib-rebase.sh b/t/lib-rebase.sh
index ec6b9b107d..b57541356b 100644
--- a/t/lib-rebase.sh
+++ b/t/lib-rebase.sh
@@ -207,3 +207,18 @@ check_reworded_commits () {
 		>reword-log &&
 	test_cmp reword-expected reword-log
 }
+
+# usage: set_replace_editor <file>
+#
+# Replace the todo file with the exact contents of the given file.
+set_replace_editor () {
+	cat >script <<-\EOF &&
+	cat FILENAME >"$1"
+
+	echo 'rebase -i script after editing:'
+	cat "$1"
+	EOF
+
+	sed -e "s/FILENAME/$1/g" <script | write_script fake-editor.sh &&
+	test_set_editor "$(pwd)/fake-editor.sh"
+}
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 2fffcf5d5f..bebf9b4def 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -1834,6 +1834,145 @@ test_expect_success '--update-refs updates refs correctly' '
 	test_cmp_rev HEAD refs/heads/no-conflict-branch
 '
 
+test_expect_success 'respect user edits to update-ref steps' '
+	git checkout -B update-refs-break no-conflict-branch &&
+	git branch -f base HEAD~4 &&
+	git branch -f first HEAD~3 &&
+	git branch -f second HEAD~3 &&
+	git branch -f third HEAD~1 &&
+	git branch -f unseen base &&
+
+	# First, we will add breaks to the expected todo file
+	cat >fake-todo-1 <<-EOF &&
+	pick $(git rev-parse HEAD~3)
+	break
+	update-ref refs/heads/second
+	update-ref refs/heads/first
+
+	pick $(git rev-parse HEAD~2)
+	pick $(git rev-parse HEAD~1)
+	update-ref refs/heads/third
+
+	pick $(git rev-parse HEAD)
+	update-ref refs/heads/no-conflict-branch
+	EOF
+
+	# Second, we will drop some update-refs commands (and move one)
+	cat >fake-todo-2 <<-EOF &&
+	update-ref refs/heads/second
+
+	pick $(git rev-parse HEAD~2)
+	update-ref refs/heads/third
+	pick $(git rev-parse HEAD~1)
+	break
+
+	pick $(git rev-parse HEAD)
+	EOF
+
+	# Third, we will:
+	# * insert a new one (new-branch),
+	# * re-add an old one (first), and
+	# * add a second instance of a previously-stored one (second)
+	cat >fake-todo-3 <<-EOF &&
+	update-ref refs/heads/unseen
+	update-ref refs/heads/new-branch
+	pick $(git rev-parse HEAD)
+	update-ref refs/heads/first
+	update-ref refs/heads/second
+	EOF
+
+	(
+		set_replace_editor fake-todo-1 &&
+		git rebase -i --update-refs primary &&
+
+		# These branches are currently locked.
+		for b in first second third no-conflict-branch
+		do
+			test_must_fail git branch -f $b base || return 1
+		done &&
+
+		set_replace_editor fake-todo-2 &&
+		git rebase --edit-todo &&
+
+		# These branches are currently locked.
+		for b in second third
+		do
+			test_must_fail git branch -f $b base || return 1
+		done &&
+
+		# These branches are currently unlocked for checkout.
+		for b in first no-conflict-branch
+		do
+			git worktree add wt-$b $b &&
+			git worktree remove wt-$b || return 1
+		done &&
+
+		git rebase --continue &&
+
+		set_replace_editor fake-todo-3 &&
+		git rebase --edit-todo &&
+
+		# These branches are currently locked.
+		for b in second third first unseen
+		do
+			test_must_fail git branch -f $b base || return 1
+		done &&
+
+		# These branches are currently unlocked for checkout.
+		for b in no-conflict-branch
+		do
+			git worktree add wt-$b $b &&
+			git worktree remove wt-$b || return 1
+		done &&
+
+		git rebase --continue
+	) &&
+
+	test_cmp_rev HEAD~2 refs/heads/third &&
+	test_cmp_rev HEAD~1 refs/heads/unseen &&
+	test_cmp_rev HEAD~1 refs/heads/new-branch &&
+	test_cmp_rev HEAD refs/heads/first &&
+	test_cmp_rev HEAD refs/heads/second &&
+	test_cmp_rev HEAD refs/heads/no-conflict-branch
+'
+
+test_expect_success '--update-refs: check failed ref update' '
+	git checkout -B update-refs-error no-conflict-branch &&
+	git branch -f base HEAD~4 &&
+	git branch -f first HEAD~3 &&
+	git branch -f second HEAD~2 &&
+	git branch -f third HEAD~1 &&
+
+	cat >fake-todo <<-EOF &&
+	pick $(git rev-parse HEAD~3)
+	break
+	update-ref refs/heads/first
+
+	pick $(git rev-parse HEAD~2)
+	update-ref refs/heads/second
+
+	pick $(git rev-parse HEAD~1)
+	update-ref refs/heads/third
+
+	pick $(git rev-parse HEAD)
+	update-ref refs/heads/no-conflict-branch
+	EOF
+
+	(
+		set_replace_editor fake-todo &&
+		git rebase -i --update-refs base
+	) &&
+
+	# At this point, the values of first, second, and third are
+	# recorded in the update-refs file. We will force-update the
+	# "second" ref, but "git branch -f" will not work because of
+	# the lock in the update-refs file.
+	git rev-parse third >.git/refs/heads/second &&
+
+	git rebase --continue 2>err &&
+	grep "update_ref failed for ref '\''refs/heads/second'\''" err
+'
+
 # This must be the last test in this file
 test_expect_success '$EDITOR and friends are unchanged' '
 	test_editor_unchanged

From 3113fedaeb67eed4c46ef7bdd670b8406317a303 Mon Sep 17 00:00:00 2001
From: Derrick Stolee <derrickstolee@github.com>
Date: Tue, 19 Jul 2022 18:33:42 +0000
Subject: [PATCH 10/12] rebase: add rebase.updateRefs config option

The previous change added the --update-refs command-line option.  For
users who always want this mode, create the rebase.updateRefs config
option which behaves the same way as rebase.autoSquash does with the
--autosquash option.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/config/rebase.txt |  3 +++
 Documentation/git-rebase.txt    |  3 +++
 builtin/rebase.c                |  5 +++++
 t/t3404-rebase-interactive.sh   | 14 ++++++++++++++
 4 files changed, 25 insertions(+)

diff --git a/Documentation/config/rebase.txt b/Documentation/config/rebase.txt
index 8c979cb20f..f19bd0e040 100644
--- a/Documentation/config/rebase.txt
+++ b/Documentation/config/rebase.txt
@@ -21,6 +21,9 @@ rebase.autoStash::
 	`--autostash` options of linkgit:git-rebase[1].
 	Defaults to false.
 
+rebase.updateRefs::
+	If set to true enable `--update-refs` option by default.
+
 rebase.missingCommitsCheck::
 	If set to "warn", git rebase -i will print a warning if some
 	commits are removed (e.g. a line was deleted), however the
diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index dfd847d661..305255f1e1 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -614,6 +614,9 @@ start would be overridden by the presence of
 	Automatically force-update any branches that point to commits that
 	are being rebased. Any branches that are checked out in a worktree
 	are not updated in this way.
++
+If the configuration variable `rebase.updateRefs` is set, then this option
+can be used to override and disable this setting.
 
 INCOMPATIBLE OPTIONS
 --------------------
diff --git a/builtin/rebase.c b/builtin/rebase.c
index 2497533e8f..56e4214b44 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -802,6 +802,11 @@ static int rebase_config(const char *var, const char *value, void *data)
 		return 0;
 	}
 
+	if (!strcmp(var, "rebase.updaterefs")) {
+		opts->update_refs = git_config_bool(var, value);
+		return 0;
+	}
+
 	if (!strcmp(var, "rebase.reschedulefailedexec")) {
 		opts->reschedule_failed_exec = git_config_bool(var, value);
 		return 0;
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index bebf9b4def..1a27bb0626 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -1772,6 +1772,12 @@ test_expect_success '--update-refs adds label and update-ref commands' '
 		EOF
 
 		test_must_fail git rebase -i --autosquash --update-refs primary >todo &&
+		test_cmp expect todo &&
+
+		test_must_fail git -c rebase.autosquash=true \
+				   -c rebase.updaterefs=true \
+				   rebase -i primary >todo &&
+
 		test_cmp expect todo
 	)
 '
@@ -1813,6 +1819,14 @@ test_expect_success '--update-refs adds commands with --rebase-merges' '
 				   --rebase-merges=rebase-cousins \
 				   --update-refs primary >todo &&
 
+		test_cmp expect todo &&
+
+		test_must_fail git -c rebase.autosquash=true \
+				   -c rebase.updaterefs=true \
+				   rebase -i \
+				   --rebase-merges=rebase-cousins \
+				   primary >todo &&
+
 		test_cmp expect todo
 	)
 '

From aa37f3e1d892698276b52f347c6374499f6c0759 Mon Sep 17 00:00:00 2001
From: Derrick Stolee <derrickstolee@github.com>
Date: Tue, 19 Jul 2022 18:33:43 +0000
Subject: [PATCH 11/12] sequencer: ignore HEAD ref under --update-refs

When using the 'git rebase -i --update-refs' option, the todo list is
populated with 'update-ref' commands for all tip refs in the history
that is being rebased. Refs that are checked out by some worktree are
instead added as a comment to warn the user that they will not be
updated.

Until now, this included the HEAD ref, which is being updated by the
rebase process itself, regardless of the --update-refs option. Remove
the comment in this case by ignoring any decorations that match the HEAD
ref.

Reported-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 sequencer.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/sequencer.c b/sequencer.c
index 20ca7b4435..f85aa6b1f7 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -5888,12 +5888,25 @@ static int add_decorations_to_list(const struct commit *commit,
 				   struct todo_add_branch_context *ctx)
 {
 	const struct name_decoration *decoration = get_name_decoration(&commit->object);
+	const char *head_ref = resolve_ref_unsafe("HEAD",
+						  RESOLVE_REF_READING,
+						  NULL,
+						  NULL);
 
 	while (decoration) {
 		struct todo_item *item;
 		const char *path;
 		size_t base_offset = ctx->buf->len;
 
+		/*
+		 * If the branch is the current HEAD, then it will be
+		 * updated by the default rebase behavior.
+		 */
+		if (head_ref && !strcmp(head_ref, decoration->name)) {
+			decoration = decoration->next;
+			continue;
+		}
+
 		ALLOC_GROW(ctx->items,
 			ctx->items_nr + 1,
 			ctx->items_alloc);

From 4611884ea883908a9638cafbd824c401c41cf7f6 Mon Sep 17 00:00:00 2001
From: Derrick Stolee <derrickstolee@github.com>
Date: Tue, 19 Jul 2022 18:33:44 +0000
Subject: [PATCH 12/12] sequencer: notify user of --update-refs activity

When the user runs 'git rebase -i --update-refs', the end message still
says only

  Successfully rebased and updated <HEAD-ref>.

Update the sequencer to collect the successful (and unsuccessful) ref
updates due to the --update-refs option, so the end message now says

  Successfully rebased and updated <HEAD-ref>.
  Updated the following refs with --update-refs:
	refs/heads/first
	refs/heads/third
  Failed to update the following refs with --update-refs:
	refs/heads/second

To test this output, we need to be very careful to format the expected
error to drop the leading tab characters. Also, we need to be aware that
the verbose output from 'git rebase' is writing progress lines which
don't use traditional newlines but clear the line after every progress
item is complete. When opening the error file in an editor, these lines
are visible, but when looking at the diff in a terminal those lines
disappear because of the characters that delete the previous characters.
Use 'sed' to clear those progress lines and clear the tabs so we can get
an exact match on our expected output.

Reported-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 sequencer.c                   | 40 +++++++++++++++++++++++++++++------
 t/t3404-rebase-interactive.sh | 37 ++++++++++++++++++++++++++++----
 2 files changed, 67 insertions(+), 10 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index f85aa6b1f7..5f22b7cd37 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4286,26 +4286,54 @@ static int do_update_ref(struct repository *r, const char *refname)
 	return 0;
 }
 
-static int do_update_refs(struct repository *r)
+static int do_update_refs(struct repository *r, int quiet)
 {
 	int res = 0;
 	struct string_list_item *item;
 	struct string_list refs_to_oids = STRING_LIST_INIT_DUP;
 	struct ref_store *refs = get_main_ref_store(r);
+	struct strbuf update_msg = STRBUF_INIT;
+	struct strbuf error_msg = STRBUF_INIT;
 
 	if ((res = sequencer_get_update_refs_state(r->gitdir, &refs_to_oids)))
 		return res;
 
 	for_each_string_list_item(item, &refs_to_oids) {
 		struct update_ref_record *rec = item->util;
+		int loop_res;
 
-		res |= refs_update_ref(refs, "rewritten during rebase",
-				       item->string,
-				       &rec->after, &rec->before,
-				       0, UPDATE_REFS_MSG_ON_ERR);
+		loop_res = refs_update_ref(refs, "rewritten during rebase",
+					   item->string,
+					   &rec->after, &rec->before,
+					   0, UPDATE_REFS_MSG_ON_ERR);
+		res |= loop_res;
+
+		if (quiet)
+			continue;
+
+		if (loop_res)
+			strbuf_addf(&error_msg, "\t%s\n", item->string);
+		else
+			strbuf_addf(&update_msg, "\t%s\n", item->string);
+	}
+
+	if (!quiet &&
+	    (update_msg.len || error_msg.len)) {
+		fprintf(stderr,
+			_("Updated the following refs with %s:\n%s"),
+			"--update-refs",
+			update_msg.buf);
+
+		if (res)
+			fprintf(stderr,
+				_("Failed to update the following refs with %s:\n%s"),
+				"--update-refs",
+				error_msg.buf);
 	}
 
 	string_list_clear(&refs_to_oids, 1);
+	strbuf_release(&update_msg);
+	strbuf_release(&error_msg);
 	return res;
 }
 
@@ -4826,7 +4854,7 @@ cleanup_head_ref:
 		strbuf_release(&buf);
 		strbuf_release(&head_ref);
 
-		if (do_update_refs(r))
+		if (do_update_refs(r, opts->quiet))
 			return -1;
 	}
 
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 1a27bb0626..688b01e3eb 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -1840,12 +1840,26 @@ test_expect_success '--update-refs updates refs correctly' '
 	test_commit extra2 fileX &&
 	git commit --amend --fixup=L &&
 
-	git rebase -i --autosquash --update-refs primary &&
+	git rebase -i --autosquash --update-refs primary 2>err &&
 
 	test_cmp_rev HEAD~3 refs/heads/first &&
 	test_cmp_rev HEAD~3 refs/heads/second &&
 	test_cmp_rev HEAD~1 refs/heads/third &&
-	test_cmp_rev HEAD refs/heads/no-conflict-branch
+	test_cmp_rev HEAD refs/heads/no-conflict-branch &&
+
+	cat >expect <<-\EOF &&
+	Successfully rebased and updated refs/heads/update-refs.
+	Updated the following refs with --update-refs:
+		refs/heads/first
+		refs/heads/no-conflict-branch
+		refs/heads/second
+		refs/heads/third
+	EOF
+
+	# Clear "Rebasing (X/Y)" progress lines and drop leading tabs.
+	sed -e "s/Rebasing.*Successfully/Successfully/g" -e "s/^\t//g" \
+		<err >err.trimmed &&
+	test_cmp expect err.trimmed
 '
 
 test_expect_success 'respect user edits to update-ref steps' '
@@ -1983,8 +1997,23 @@ test_expect_success '--update-refs: check failed ref update' '
 	# the lock in the update-refs file.
 	git rev-parse third >.git/refs/heads/second &&
 
-	git rebase --continue 2>err &&
-	grep "update_ref failed for ref '\''refs/heads/second'\''" err
+	test_must_fail git rebase --continue 2>err &&
+	grep "update_ref failed for ref '\''refs/heads/second'\''" err &&
+
+	cat >expect <<-\EOF &&
+	Updated the following refs with --update-refs:
+		refs/heads/first
+		refs/heads/no-conflict-branch
+		refs/heads/third
+	Failed to update the following refs with --update-refs:
+		refs/heads/second
+	EOF
+
+	# Clear "Rebasing (X/Y)" progress lines and drop leading tabs.
+	tail -n 6 err >err.last &&
+	sed -e "s/Rebasing.*Successfully/Successfully/g" -e "s/^\t//g" \
+		<err.last >err.trimmed &&
+	test_cmp expect err.trimmed
 '
 
 # This must be the last test in this file