Merge branch 'fz/rebase-autosquash-empty' into seen

A commit that is emptied by melding a 'fixup!' or 'squash!' commit
during 'git rebase --autosquash' is now handled according to the
'--empty' option, allowing it to be dropped, kept, or to halt the
rebase.

* fz/rebase-autosquash-empty:
  sequencer: honor --empty when a fixup!/squash! empties its target

Documentation/git-rebase.adoc

@@ -292,6 +292,11 @@ by `git log --cherry-mark ...`) are detected and dropped as a
 preliminary step (unless `--reapply-cherry-picks` or `--keep-base` is
 passed).
 +
+A commit can also become empty when `--autosquash` squashes a `fixup!`
+or `squash!` commit into it that cancels out all of its changes.  This
+option governs such a commit as well; it is dropped, kept, or stopped
+at just like a commit that becomes empty when it is picked.
++
 See also INCOMPATIBLE OPTIONS below.
 
 --no-keep-empty::
@@ -601,6 +606,12 @@ changed from `pick` to `squash`, `fixup` or `fixup -C`, respectively, and they
 are moved right after the commit they modify.  The `--interactive` option can
 be used to review and edit the todo list before proceeding.
 +
+Squashing a `fixup!` or `squash!` commit into its target can cancel out all
+of the changes of that target, leaving an empty commit behind.  What happens
+then is governed by the `--empty` option, so a change can be backed out of a
+series by committing a revert of it as a `fixup!` and letting
+`--autosquash --empty=drop` remove the two together.
++
 The recommended way to create commits with squash markers is by using the
 `--squash`, `--fixup`, `--fixup=amend:` or `--fixup=reword:` options of
 linkgit:git-commit[1], which take the target commit as an argument and

sequencer.c

@@ -217,6 +217,31 @@ 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")
 static GIT_PATH_FUNC(rebase_path_trailer, "rebase-merge/trailer")
+/*
+ * The file that remembers, across a stop for conflict resolution, what
+ * "enum fixup_target" recorded about the commit a chain of fixup and
+ * squash commands is being applied to.
+ */
+static GIT_PATH_FUNC(rebase_path_fixup_target, "rebase-merge/fixup-target")
+
+/*
+ * What we know about the commit that the current chain of fixup and squash
+ * commands is being applied to.  A commit is only dropped when squashing
+ * the fixups into it empties it out if it was picked with changes of its
+ * own, so anything but FIXUP_TARGET_PICKED_NONEMPTY keeps it.
+ */
+enum fixup_target {
+	/*
+	 * The commit was not created by a "pick", either because it was
+	 * dropped or because the todo list starts the chain with some
+	 * other command such as "reset", "exec" or "break".
+	 */
+	FIXUP_TARGET_UNKNOWN = 0,
+	/* The commit was picked empty, so the fixups did not empty it. */
+	FIXUP_TARGET_PICKED_EMPTY,
+	/* The commit was picked with changes, so the fixups may empty it. */
+	FIXUP_TARGET_PICKED_NONEMPTY
+};
 
 /*
  * A 'struct replay_ctx' represents the private state of the sequencer.
@@ -241,6 +266,11 @@ struct replay_ctx {
 	 * Whether message contains a commit message.
 	 */
 	unsigned have_message :1;
+	/*
+	 * What the commit that the current chain of fixup and squash
+	 * commands is being applied to was picked as.
+	 */
+	enum fixup_target fixup_target;
 };
 
 struct replay_ctx* replay_ctx_new(void)
@@ -594,6 +624,38 @@ static int write_message(const void *buf, size_t len, const char *filename,
 	return 0;
 }
 
+/* The two names that rebase_path_fixup_target() stores. */
+static const char *const fixup_target_name[] = {
+	[FIXUP_TARGET_PICKED_EMPTY] = "picked-empty",
+	[FIXUP_TARGET_PICKED_NONEMPTY] = "picked-non-empty"
+};
+
+/*
+ * Remember what the commit that the current chain of fixup and squash
+ * commands is being applied to was picked as, both in the sequencer state
+ * and on disk so that it survives a stop for conflict resolution.
+ */
+static int set_fixup_target(struct replay_opts *opts, enum fixup_target target)
+{
+	struct replay_ctx *ctx = opts->ctx;
+	const char *name;
+
+	if (ctx->fixup_target == target)
+		return 0;
+
+	ctx->fixup_target = target;
+	if (!is_rebase_i(opts))
+		return 0;
+
+	if (target == FIXUP_TARGET_UNKNOWN) {
+		unlink(rebase_path_fixup_target());
+		return 0;
+	}
+
+	name = fixup_target_name[target];
+	return write_message(name, strlen(name), rebase_path_fixup_target(), 1);
+}
+
 int read_oneliner(struct strbuf *buf,
 	const char *path, unsigned flags)
 {
@@ -1825,6 +1887,41 @@ static int allow_empty(struct repository *r,
 		return 0;
 }
 
+/*
+ * A "fixup" or "squash" is applied by amending HEAD, so the commit it
+ * produces is empty when the index matches the tree of HEAD's parent,
+ * rather than the tree of HEAD itself that is_index_unchanged() looks at.
+ * Returns 1 if amending HEAD would leave it empty, 0 if not, and negative
+ * on error.
+ */
+static int is_amended_head_empty(struct repository *r)
+{
+	const struct object_id *parent_tree_oid;
+	struct object_id *cache_tree_oid;
+	struct commit *head;
+
+	head = lookup_commit_reference_by_name("HEAD");
+	if (!head || repo_parse_commit(r, head))
+		return error(_("could not parse HEAD commit"));
+
+	if (head->parents) {
+		struct commit *parent = head->parents->item;
+
+		if (repo_parse_commit(r, parent))
+			return error(_("could not parse parent commit %s"),
+				     oid_to_hex(&parent->object.oid));
+		parent_tree_oid = get_commit_tree_oid(parent);
+	} else {
+		parent_tree_oid = the_hash_algo->empty_tree; /* HEAD is root */
+	}
+
+	cache_tree_oid = get_cache_tree_oid(r->index);
+	if (!cache_tree_oid)
+		return -1;
+
+	return oideq(cache_tree_oid, parent_tree_oid);
+}
+
 static struct {
 	char c;
 	const char *str;
@@ -2307,11 +2404,39 @@ static const char *reflog_message(struct replay_opts *opts,
 	return buf.buf;
 }
 
+/*
+ * Drop the commit at HEAD by moving HEAD back to its parent.  The index and
+ * the worktree already match the tree of that parent, so nothing else needs
+ * to be updated.  "action" names the command doing the dropping and is only
+ * used for the reflog message.
+ */
+static int drop_head_commit(struct repository *r, struct replay_opts *opts,
+			    const char *action)
+{
+	struct commit *head = lookup_commit_reference_by_name("HEAD");
+
+	if (!head || repo_parse_commit(r, head))
+		return error(_("could not parse HEAD commit"));
+	if (!head->parents)
+		return error(_("cannot drop the root commit"));
+
+	return refs_update_ref(get_main_ref_store(r),
+			       reflog_message(opts, action,
+					      "dropping emptied commit"),
+			       "HEAD", &head->parents->item->object.oid,
+			       &head->object.oid, 0, UPDATE_REFS_MSG_ON_ERR);
+}
+
 enum pick_result {
 	PICK_RESULT_ERROR = -1,
 	PICK_RESULT_OK,
 	PICK_RESULT_CONFLICTS,
 	PICK_RESULT_DROPPED,
+	/*
+	 * The fixups were squashed into a commit that they emptied out, so
+	 * that commit was dropped along with them.
+	 */
+	PICK_RESULT_DROPPED_HEAD,
 };
 
 static enum pick_result do_pick_commit(struct repository *r,
@@ -2327,7 +2452,7 @@ static enum pick_result do_pick_commit(struct repository *r,
 	const char *base_label, *next_label, *reflog_action;
 	char *author = NULL;
 	struct commit_message msg = { NULL, NULL, NULL, NULL };
-	int res, unborn = 0, reword = 0, allow, drop_commit = 0;
+	int res, unborn = 0, reword = 0, allow, drop_commit = 0, drop_head = 0;
 	enum todo_command command = item->command;
 	struct commit *commit = item->commit;
 
@@ -2337,6 +2462,20 @@ static enum pick_result do_pick_commit(struct repository *r,
 	else
 		reflog_action = sequencer_reflog_action(opts);
 
+	/*
+	 * Remember whether this commit is picked with changes of its own, as
+	 * only such a commit is dropped when the fixups that follow it empty
+	 * it out again.
+	 */
+	if (is_rebase_i(opts) && command == TODO_PICK) {
+		int empty = is_original_commit_empty(commit);
+
+		if (empty < 0 ||
+		    set_fixup_target(opts, empty ? FIXUP_TARGET_PICKED_EMPTY :
+				     FIXUP_TARGET_PICKED_NONEMPTY))
+			return PICK_RESULT_ERROR;
+	}
+
 	if (opts->no_commit) {
 		/*
 		 * We do not intend to commit immediately.  We just want to
@@ -2574,7 +2713,51 @@ static enum pick_result do_pick_commit(struct repository *r,
 			_("dropping %s %s -- patch contents already upstream\n"),
 			oid_to_hex(&commit->object.oid), msg.subject);
 	} /* else allow == 0 and there's nothing special to do */
-	if (!opts->no_commit && !drop_commit) {
+
+	/*
+	 * allow_empty() above only notices a commit that adds nothing to
+	 * HEAD.  A "fixup" or "squash" can also cancel out the changes of
+	 * the commit it is squashed into, which leaves that commit empty
+	 * instead, so check for that here and honor --empty for it.
+	 */
+	if ((flags & AMEND_MSG) && !drop_commit &&
+	    ctx->fixup_target == FIXUP_TARGET_PICKED_NONEMPTY) {
+		int emptied = is_amended_head_empty(r);
+
+		if (emptied < 0) {
+			res = emptied;
+			goto leave;
+		}
+
+		if (emptied && (!final_fixup || opts->keep_redundant_commits)) {
+			/*
+			 * Keep the commit, empty for now, when more fixups
+			 * are still to be squashed into it, as dropping it
+			 * here would squash them into the previous commit
+			 * instead.  Also keep it when --empty=keep asks us to.
+			 */
+			flags |= ALLOW_EMPTY;
+		} else if (emptied && opts->drop_redundant_commits) {
+			unlink(git_path_merge_msg(r));
+			refs_delete_ref(get_main_ref_store(r), "", "AUTO_MERGE",
+					NULL, REF_NO_DEREF);
+			res = drop_head_commit(r, opts,
+					       command_to_string(command));
+			if (res)
+				goto leave;
+			drop_head = 1;
+			fprintf(stderr,
+				_("dropping %s %s -- squashing it in empties the commit\n"),
+				oid_to_hex(&commit->object.oid), msg.subject);
+		}
+		/*
+		 * Otherwise --empty=stop is in effect, and "git commit
+		 * --amend" below refuses to make the commit empty, which
+		 * halts the rebase.
+		 */
+	}
+
+	if (!opts->no_commit && !drop_commit && !drop_head) {
 		if (author || command == TODO_REVERT || (flags & AMEND_MSG))
 			res = do_commit(r, msg_file, author, reflog_action,
 					opts, flags,
@@ -2621,6 +2804,8 @@ leave:
 		return PICK_RESULT_ERROR;
 	else if (res > 0)
 		return PICK_RESULT_CONFLICTS;
+	else if (drop_head)
+		return PICK_RESULT_DROPPED_HEAD;
 	else if (drop_commit)
 		return PICK_RESULT_DROPPED;
 	else
@@ -3352,6 +3537,17 @@ static int read_populate_opts(struct replay_opts *opts)
 		}
 		strbuf_reset(&buf);
 
+		if (read_oneliner(&buf, rebase_path_fixup_target(),
+				  READ_ONELINER_SKIP_IF_EMPTY)) {
+			enum fixup_target target;
+
+			for (target = FIXUP_TARGET_PICKED_EMPTY;
+			     target <= FIXUP_TARGET_PICKED_NONEMPTY; target++)
+				if (!strcmp(buf.buf, fixup_target_name[target]))
+					ctx->fixup_target = target;
+			strbuf_reset(&buf);
+		}
+
 		if (read_oneliner(&ctx->current_fixups,
 				  rebase_path_current_fixups(),
 				  READ_ONELINER_SKIP_IF_EMPTY)) {
@@ -5092,9 +5288,26 @@ static int pick_one_commit(struct repository *r,
 				    peek_command(todo_list, 1));
 		return 0;
 	} else if (pick_res == PICK_RESULT_DROPPED) {
+		/*
+		 * When a "pick" is dropped HEAD stays where it was, so a
+		 * "fixup" that follows would be squashed into a commit we
+		 * know nothing about.  A dropped "fixup" on the other hand
+		 * leaves the commit it targets untouched.
+		 */
+		if (!is_fixup(item->command))
+			set_fixup_target(opts, FIXUP_TARGET_UNKNOWN);
 		if (is_final_fixup(todo_list))
 			flush_rewritten_pending();
 		return 0;
+	} else if (pick_res == PICK_RESULT_DROPPED_HEAD) {
+		/*
+		 * The commit the fixups were squashed into is gone, so
+		 * neither it nor any of them were rewritten and there is
+		 * nothing left for the post-rewrite machinery to report.
+		 */
+		unlink(rebase_path_rewritten_pending());
+		set_fixup_target(opts, FIXUP_TARGET_UNKNOWN);
+		return 0;
 	} else if (pick_res == PICK_RESULT_CONFLICTS &&
 		   is_fixup(item->command)) {
 		return error_failed_squash(r, item->commit, opts,
@@ -5150,6 +5363,16 @@ static int pick_commits(struct repository *r,
 
 		if (save_todo(todo_list, opts, reschedule))
 			return -1;
+
+		/*
+		 * Only a commit created by a "pick" is dropped when the
+		 * fixups squashed into it empty it out, so forget about the
+		 * last "pick" as soon as any other command runs.
+		 */
+		if (item->command != TODO_PICK && !is_fixup(item->command) &&
+		    !is_noop(item->command))
+			set_fixup_target(opts, FIXUP_TARGET_UNKNOWN);
+
 		if (is_rebase_i(opts)) {
 			if (item->command != TODO_COMMENT) {
 				FILE *f = fopen(rebase_path_msgnum(), "w");
@@ -5555,6 +5778,53 @@ static int commit_staged_changes(struct repository *r,
 		}
 	}
 
+	/*
+	 * If resolving the conflicts of the last "fixup" or "squash" of a
+	 * chain undid the commit they are being squashed into, honor
+	 * --empty for that commit just as do_pick_commit() does when the
+	 * chain applies cleanly.
+	 */
+	if ((flags & AMEND_MSG) && opts->drop_redundant_commits &&
+	    ctx->fixup_target == FIXUP_TARGET_PICKED_NONEMPTY &&
+	    !is_fixup(peek_command(todo_list, 0))) {
+		int emptied = is_amended_head_empty(r);
+
+		if (emptied < 0) {
+			ret = emptied;
+			goto out;
+		}
+		if (emptied) {
+			ret = drop_head_commit(r, opts, "continue");
+			if (ret)
+				goto out;
+
+			/*
+			 * Neither the dropped commit nor the fixups squashed
+			 * into it were rewritten, so leave nothing behind for
+			 * the post-rewrite machinery to report.
+			 */
+			unlink(rebase_path_stopped_sha());
+			unlink(rebase_path_rewritten_pending());
+			set_fixup_target(opts, FIXUP_TARGET_UNKNOWN);
+
+			unlink(rebase_path_amend());
+			unlink(rebase_path_fixup_msg());
+			unlink(rebase_path_squash_msg());
+			unlink(git_path_merge_head(r));
+			unlink(git_path_merge_msg(r));
+			refs_delete_ref(get_main_ref_store(r), "", "AUTO_MERGE",
+					NULL, REF_NO_DEREF);
+			if (ctx->current_fixup_count > 0) {
+				unlink(rebase_path_current_fixups());
+				strbuf_reset(&ctx->current_fixups);
+				ctx->current_fixup_count = 0;
+			}
+
+			ret = 0;
+			goto out;
+		}
+	}
+
 	finalize_continue_edit_flags(opts, &flags);
 
 	if (run_git_commit(final_fixup ? NULL : rebase_path_message(),
@@ -6531,6 +6801,7 @@ int todo_list_write_to_file(struct repository *r, struct todo_list *todo_list,
 
 /* skip picking commits whose parents are unchanged */
 static int skip_unnecessary_picks(struct repository *r,
+				  struct replay_opts *opts,
 				  struct todo_list *todo_list,
 				  struct object_id *base_oid)
 {
@@ -6570,8 +6841,28 @@ static int skip_unnecessary_picks(struct repository *r,
 		todo_list->current = 0;
 		todo_list->done_nr += i;
 
-		if (is_fixup(peek_command(todo_list, 0)))
+		if (is_fixup(peek_command(todo_list, 0))) {
+			/*
+			 * The picks that were skipped never reach
+			 * do_pick_commit(), so record here what the last of
+			 * them left at HEAD for the fixups that follow it.
+			 */
+			struct commit *base = lookup_commit_reference(r,
+								      base_oid);
+			int empty;
+
+			if (!base)
+				return error(_("could not parse commit '%s'"),
+					     oid_to_hex(base_oid));
+			empty = is_original_commit_empty(base);
+			if (empty < 0 ||
+			    set_fixup_target(opts,
+					     empty ? FIXUP_TARGET_PICKED_EMPTY :
+					     FIXUP_TARGET_PICKED_NONEMPTY))
+				return -1;
+
 			record_in_rewritten(base_oid, peek_command(todo_list, 0));
+		}
 	}
 
 	return 0;
@@ -6809,7 +7100,7 @@ int complete_action(struct repository *r, struct replay_opts *opts, unsigned fla
 		BUG("invalid todo list after expanding IDs:\n%s",
 		    new_todo.buf.buf);
 
-	if (opts->allow_ff && skip_unnecessary_picks(r, &new_todo, &oid)) {
+	if (opts->allow_ff && skip_unnecessary_picks(r, opts, &new_todo, &oid)) {
 		todo_list_release(&new_todo);
 		return error(_("could not skip unnecessary pick commands"));
 	}

t/t3415-rebase-autosquash.sh

@@ -510,4 +510,155 @@ test_expect_success 'pick and fixup respect commit.cleanup' '
 	test_commit_message HEAD -m "something"
 '
 
+test_expect_success 'fixup! that empties its target is dropped with --empty=drop' '
+	git reset --hard base &&
+	test_commit --no-tag addX fileX 1 &&
+	test_commit --no-tag changeX fileX 2 &&
+	test_commit --no-tag later fileW hello &&
+	echo 1 >fileX &&
+	git commit -m "fixup! changeX" fileX &&
+
+	git rebase -i --autosquash --empty=drop HEAD~4 &&
+
+	git log --format=%s >actual &&
+	test_grep ! changeX actual &&
+	test_grep addX actual &&
+	test_grep later actual &&
+	echo 1 >expect &&
+	test_cmp expect fileX &&
+	echo hello >expect &&
+	test_cmp expect fileW
+'
+
+test_expect_success 'fixup! that empties its target is kept with --empty=keep' '
+	git reset --hard base &&
+	test_commit --no-tag addY fileY 1 &&
+	test_commit --no-tag changeY fileY 2 &&
+	echo 1 >fileY &&
+	git commit -m "fixup! changeY" fileY &&
+
+	git rebase -i --autosquash --empty=keep HEAD~3 &&
+
+	git log --format=%s >actual &&
+	test_grep changeY actual &&
+	: "the commit that was kept is empty" &&
+	git diff --exit-code HEAD~1 HEAD &&
+	echo 1 >expect &&
+	test_cmp expect fileY
+'
+
+test_expect_success 'fixup! that empties its target halts by default' '
+	git reset --hard base &&
+	test_commit --no-tag addZ fileZ 1 &&
+	test_commit --no-tag changeZ fileZ 2 &&
+	echo 1 >fileZ &&
+	git commit -m "fixup! changeZ" fileZ &&
+
+	test_when_finished "git rebase --abort" &&
+	test_must_fail git rebase -i --autosquash HEAD~3
+'
+
+test_expect_success 'squash! that empties its target is dropped with --empty=drop' '
+	git reset --hard base &&
+	test_commit --no-tag addS fileS 1 &&
+	test_commit --no-tag changeS fileS 2 &&
+	echo 1 >fileS &&
+	git commit -m "squash! changeS" fileS &&
+
+	git rebase -i --autosquash --empty=drop HEAD~3 &&
+
+	git log --format=%s >actual &&
+	test_grep ! changeS actual &&
+	test_grep addS actual &&
+	echo 1 >expect &&
+	test_cmp expect fileS
+'
+
+test_expect_success 'a target emptied in the middle of a chain is not dropped' '
+	git reset --hard base &&
+	test_commit --no-tag addM fileM 1 &&
+	test_commit --no-tag changeM fileM 2 &&
+	echo 1 >fileM &&
+	git commit -m "fixup! changeM" fileM &&
+	test_commit --no-tag "fixup! changeM" fileN later &&
+
+	git rebase -i --autosquash --empty=drop HEAD~4 &&
+
+	: "the second fixup! refills the commit the first one emptied" &&
+	git log --format=%s >actual &&
+	test_grep changeM actual &&
+	echo 1 >expect &&
+	test_cmp expect fileM &&
+	echo later >expect &&
+	test_cmp expect fileN
+'
+
+test_expect_success 'a commit picked empty is kept when a fixup! leaves it empty' '
+	git reset --hard base &&
+	git commit --allow-empty -m placeholder &&
+	git commit --allow-empty -m "fixup! placeholder" &&
+
+	git rebase -i --autosquash --empty=drop HEAD~2 &&
+
+	: "--empty only governs commits that become empty" &&
+	git log --format=%s >actual &&
+	test_grep placeholder actual &&
+	git diff --exit-code HEAD~1 HEAD
+'
+
+test_expect_success 'fixup! filling in an empty commit keeps a non-empty commit' '
+	git reset --hard base &&
+	git commit --allow-empty -m placeholder &&
+	test_commit --no-tag "fixup! placeholder" fileP content &&
+
+	git rebase -i --autosquash --empty=drop HEAD~2 &&
+
+	git log --format=%s >actual &&
+	test_grep placeholder actual &&
+	echo content >expect &&
+	test_cmp expect fileP &&
+	test_must_fail git diff --exit-code HEAD~1 HEAD
+'
+
+test_expect_success 'a fixup! not preceded by a pick does not drop its target' '
+	git reset --hard base &&
+	test_commit --no-tag addQ fileQ 1 &&
+	test_commit --no-tag changeQ fileQ 2 &&
+	echo 1 >fileQ &&
+	git commit -m "fixup! changeQ" fileQ &&
+
+	: "an exec between the pick and the fixup hides what was picked" &&
+	test_when_finished "git rebase --abort" &&
+	set_fake_editor &&
+	test_must_fail env FAKE_LINES="1 2 exec_true 3" \
+		git rebase -i --autosquash --empty=drop HEAD~3
+'
+
+test_expect_success 'resolving a conflicted fixup! by emptying its target drops it' '
+	git reset --hard base &&
+	test_commit --no-tag addC fileC 1 &&
+	test_commit --no-tag changeC fileC 2 &&
+	test_commit --no-tag otherC fileC 3 &&
+	echo 1 >fileC &&
+	git commit -m "fixup! changeC" fileC &&
+
+	test_when_finished "test_might_fail git rebase --abort" &&
+	: "the fixup! is built on otherC, so it conflicts with changeC" &&
+	test_must_fail git rebase -i --autosquash --empty=drop HEAD~4 &&
+
+	: "resolve it by undoing changeC, which leaves changeC empty" &&
+	echo 1 >fileC &&
+	git add fileC &&
+	: "changeC is now gone, so otherC conflicts with addC" &&
+	test_must_fail git rebase --continue &&
+	echo 3 >fileC &&
+	git add fileC &&
+	git rebase --continue &&
+
+	git log --format=%s >actual &&
+	test_grep ! changeC actual &&
+	test_grep addC actual &&
+	test_grep otherC actual
+'
+
 test_done

t/t5407-post-rewrite-hook.sh

@@ -333,4 +333,25 @@ test_expect_success 'rebase with commits that become empty' '
 	verify_hook_input
 '
 
+test_expect_success 'rebase drops a commit that its fixup empties' '
+	git checkout -b empty-fixup A &&
+	test_commit --no-tag P1 file1 one &&
+	test_commit --no-tag P2 file1 two &&
+	test_commit --no-tag P3 file2 three &&
+	echo one >file1 &&
+	git commit -m "fixup! P2" file1 &&
+	p1=$(git rev-parse HEAD~3) &&
+	p3=$(git rev-parse HEAD~1) &&
+	clear_hook_input &&
+
+	git rebase -i --autosquash --empty=drop B &&
+
+	echo rebase >expected.args &&
+	cat >expected.data <<-EOF &&
+	$p1 $(git rev-parse HEAD~1)
+	$p3 $(git rev-parse HEAD)
+	EOF
+	verify_hook_input
+'
+
 test_done