rebase -i: comment out squash!/fixup! subjects from squash message

When squashing commit messages the squash!/fixup! subjects are not of
interest so comment them out to stop them becoming part of the final
message.

This change breaks a bunch of --autosquash tests which rely on the
"squash! <subject>" line appearing in the final commit message. This is
addressed by adding a second line to the commit message of the "squash!
..." commits and testing for that.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Charvi Mendiratta <charvi077@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer.c

@@ -1718,15 +1718,34 @@ static int is_pick_or_similar(enum todo_command command)
 	}
 }
 
+static size_t subject_length(const char *body)
+{
+	const char *p = body;
+	while (*p) {
+		const char *next = skip_blank_lines(p);
+		if (next != p)
+			break;
+		p = strchrnul(p, '\n');
+		if (*p)
+			p++;
+	}
+	return p - body;
+}
+
 static void append_squash_message(struct strbuf *buf, const char *body,
 				  struct replay_opts *opts)
 {
+	size_t commented_len = 0;
+
 	unlink(rebase_path_fixup_msg());
+	if (starts_with(body, "squash!") || starts_with(body, "fixup!"))
+		commented_len = subject_length(body);
 	strbuf_addf(buf, "\n%c ", comment_line_char);
 	strbuf_addf(buf, _("This is the commit message #%d:"),
 		    ++opts->current_fixup_count + 1);
 	strbuf_addstr(buf, "\n\n");
-	strbuf_addstr(buf, body);
+	strbuf_add_commented_lines(buf, body, commented_len);
+	strbuf_addstr(buf, body + commented_len);
 }
 
 static int update_squash_messages(struct repository *r,

t/t3415-rebase-autosquash.sh

@@ -81,8 +81,7 @@ test_auto_squash () {
 	echo 1 >file1 &&
 	git add -u &&
 	test_tick &&
-	git commit -m "squash! first" &&
-
+	git commit -m "squash! first" -m "extra para for first" &&
 	git tag $1 &&
 	test_tick &&
 	git rebase $2 -i HEAD^^^ &&
@@ -139,7 +138,7 @@ test_expect_success 'auto squash that matches 2 commits' '
 	echo 1 >file1 &&
 	git add -u &&
 	test_tick &&
-	git commit -m "squash! first" &&
+	git commit -m "squash! first" -m "extra para for first" &&
 	git tag final-multisquash &&
 	test_tick &&
 	git rebase --autosquash -i HEAD~4 &&
@@ -192,7 +191,7 @@ test_expect_success 'auto squash that matches a sha1' '
 	git add -u &&
 	test_tick &&
 	oid=$(git rev-parse --short HEAD^) &&
-	git commit -m "squash! $oid" &&
+	git commit -m "squash! $oid" -m "extra para" &&
 	git tag final-shasquash &&
 	test_tick &&
 	git rebase --autosquash -i HEAD^^^ &&
@@ -203,7 +202,8 @@ test_expect_success 'auto squash that matches a sha1' '
 	git cat-file blob HEAD^:file1 >actual &&
 	test_cmp expect actual &&
 	git cat-file commit HEAD^ >commit &&
-	grep squash commit >actual &&
+	! grep "squash" commit &&
+	grep "^extra para" commit >actual &&
 	test_line_count = 1 actual
 '
 
@@ -213,7 +213,7 @@ test_expect_success 'auto squash that matches longer sha1' '
 	git add -u &&
 	test_tick &&
 	oid=$(git rev-parse --short=11 HEAD^) &&
-	git commit -m "squash! $oid" &&
+	git commit -m "squash! $oid" -m "extra para" &&
 	git tag final-longshasquash &&
 	test_tick &&
 	git rebase --autosquash -i HEAD^^^ &&
@@ -224,7 +224,8 @@ test_expect_success 'auto squash that matches longer sha1' '
 	git cat-file blob HEAD^:file1 >actual &&
 	test_cmp expect actual &&
 	git cat-file commit HEAD^ >commit &&
-	grep squash commit >actual &&
+	! grep "squash" commit &&
+	grep "^extra para" commit >actual &&
 	test_line_count = 1 actual
 '
 
@@ -233,7 +234,7 @@ test_auto_commit_flags () {
 	echo 1 >file1 &&
 	git add -u &&
 	test_tick &&
-	git commit --$1 first-commit &&
+	git commit --$1 first-commit -m "extra para for first" &&
 	git tag final-commit-$1 &&
 	test_tick &&
 	git rebase --autosquash -i HEAD^^^ &&
@@ -261,11 +262,11 @@ test_auto_fixup_fixup () {
 	echo 1 >file1 &&
 	git add -u &&
 	test_tick &&
-	git commit -m "$1! first" &&
+	git commit -m "$1! first" -m "extra para for first" &&
 	echo 2 >file1 &&
 	git add -u &&
 	test_tick &&
-	git commit -m "$1! $2! first" &&
+	git commit -m "$1! $2! first" -m "second extra para for first" &&
 	git tag "final-$1-$2" &&
 	test_tick &&
 	(
@@ -326,12 +327,12 @@ test_expect_success C_LOCALE_OUTPUT 'autosquash with custom inst format' '
 	git add -u &&
 	test_tick &&
 	oid=$(git rev-parse --short HEAD^) &&
-	git commit -m "squash! $oid" &&
+	git commit -m "squash! $oid" -m "extra para for first" &&
 	echo 1 >file1 &&
 	git add -u &&
 	test_tick &&
 	subject=$(git log -n 1 --format=%s HEAD~2) &&
-	git commit -m "squash! $subject" &&
+	git commit -m "squash! $subject" -m "second extra para for first" &&
 	git tag final-squash-instFmt &&
 	test_tick &&
 	git rebase --autosquash -i HEAD~4 &&
@@ -342,8 +343,9 @@ test_expect_success C_LOCALE_OUTPUT 'autosquash with custom inst format' '
 	git cat-file blob HEAD^:file1 >actual &&
 	test_cmp expect actual &&
 	git cat-file commit HEAD^ >commit &&
-	grep squash commit >actual &&
-	test_line_count = 2 actual
+	! grep "squash" commit &&
+	grep first commit >actual &&
+	test_line_count = 3 actual
 '
 
 test_expect_success 'autosquash with empty custom instructionFormat' '

t/t3900-i18n-commit.sh

@@ -226,10 +226,6 @@ test_commit_autosquash_multi_encoding () {
 		git rev-list HEAD >actual &&
 		test_line_count = 3 actual &&
 		iconv -f $old -t UTF-8 "$TEST_DIRECTORY"/t3900/$msg >expect &&
-		if test $flag = squash; then
-			subject="$(head -1 expect)" &&
-			printf "\nsquash! %s\n" "$subject" >>expect
-		fi &&
 		git cat-file commit HEAD^ >raw &&
 		(sed "1,/^$/d" raw | iconv -f $new -t utf-8) >actual &&
 		test_cmp expect actual