add-patch: update hunk splitability after editing

When the user edits a hunk if they change deletion lines to context
lines or vice versa then the number of hunks that the edited hunk
can be split into may differ from the unedited hunk and so we need
to update hunk->splittable_into. In practice users are unlikely to
hit this bug as it is doubtful that a user who has edited a hunk will
split it afterwards.

Signed-off-by: Phillip Wood <[email protected]>

Author: phillipwood

add-patch.c

@@ -1188,19 +1188,29 @@ static ssize_t recount_edited_hunk(struct add_p_state *s, struct hunk *hunk,
 {
 	struct hunk_header *header = &hunk->header;
 	size_t i;
+	char ch, marker = ' ';
 
+	hunk->splittable_into = 0;
 	header->old_count = header->new_count = 0;
 	for (i = hunk->start; i < hunk->end; ) {
-		switch(normalize_marker(&s->plain.buf[i])) {
+		ch = normalize_marker(&s->plain.buf[i]);
+		switch (ch) {
 		case '-':
 			header->old_count++;
+			if (marker == ' ')
+				hunk->splittable_into++;
+			marker = ch;
 			break;
 		case '+':
 			header->new_count++;
+			if (marker == ' ')
+				hunk->splittable_into++;
+			marker = ch;
 			break;
 		case ' ':
 			header->old_count++;
 			header->new_count++;
+			marker = ch;
 			break;
 		}
 

t/t3701-add-interactive.sh

@@ -1240,4 +1240,30 @@ test_expect_success WITH_BREAKING_CHANGES 'splitting previous hunk marks split h
 	test_cmp expect actual
 '
 
+test_expect_success 'splitting edited hunk' '
+	# Before the first hunk is edited it can be split into two
+	# hunks, after editing it can be split into three hunks.
+
+	write_script fake-editor.sh <<-\EOF &&
+	sed "s/^ c/-c/" "$1" >"$1.tmp" &&
+	mv "$1.tmp" "$1"
+	EOF
+
+	test_write_lines a b c d e f g h i j k l m n >file &&
+	git add file &&
+	test_write_lines A b c d E f g h i j k l M n >file &&
+	(
+		test_set_editor "$(pwd)/fake-editor.sh" &&
+		if test_have_prereq WITH_BREAKING_CHANGES
+		then
+			test_write_lines e K s j y n y q
+		else
+			test_write_lines e K s n K n y q
+		fi | git add -p file
+	) &&
+	git cat-file blob :file >actual &&
+	test_write_lines a b d e f g h i j k l M n >expect &&
+	test_cmp expect actual
+'
+
 test_done