add -p: mark split hunks as undecided

When a hunk is split each of the new hunks inherits whether it is
selected or not from the original hunk. This means that if a selected
hunk is split all of the new hunks are selected and the user is not asked
whether or not they want to select the new hunks. This is unfortunate as
the user is presumably splitting the original hunk because they only
want to select some sub-set of it. Fix this by marking all the new hunks
as "undecided" so that we prompt the user to decide whether to select
them or not.

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

add-patch.c

@@ -953,6 +953,7 @@ static int split_hunk(struct add_p_state *s, struct file_diff *file_diff,
 			* sizeof(*hunk));
 	hunk = file_diff->hunk + hunk_index;
 	hunk->splittable_into = 1;
+	hunk->use = UNDECIDED_HUNK;
 	memset(hunk + 1, 0, (splittable_into - 1) * sizeof(*hunk));
 
 	header = &hunk->header;
@@ -1054,7 +1055,7 @@ static int split_hunk(struct add_p_state *s, struct file_diff *file_diff,
 
 		hunk++;
 		hunk->splittable_into = 1;
-		hunk->use = hunk[-1].use;
+		hunk->use = UNDECIDED_HUNK;
 		header = &hunk->header;
 
 		header->old_count = header->new_count = context_line_count;

t/t3701-add-interactive.sh

@@ -1230,4 +1230,14 @@ test_expect_success 'hunk splitting works with diff.suppressBlankEmpty' '
 	test_cmp expect actual
 '
 
+test_expect_success 'splitting previous hunk marks split hunks as undecided' '
+	test_write_lines a " " b c d e f g h i j k >file &&
+	git add file &&
+	test_write_lines x " " b y d e f g h i j x >file &&
+	test_write_lines n K s n y q | git add -p file &&
+	git cat-file blob :file >actual &&
+	test_write_lines a " " b y d e f g h i j k >expect &&
+	test_cmp expect actual
+'
+
 test_done