add-patch: let options y, n, j, and e roll over to next undecided

The options y, n, and e mark the current hunk as decided.  If there's
another undecided hunk towards the bottom of the hunk array they go
there.  If there isn't, but there is another undecided hunk towards the
top then they go to the very first hunk, no matter if it has already
been decided on.

The option j does basically the same move.  Technically it is not
allowed if there's no undecided hunk towards the bottom, but the
variable "permitted" is never reset, so this permission is retained
from the very first hunk.  That may a bug, but this behavior is at
least consistent with y, n, and e and arguably more useful than
refusing to move.

Improve the roll-over behavior of these four options by moving to the
first undecided hunk instead of hunk 1, consistent with what they do
when not rolling over.

Also adjust the error message for j, as it will only be shown if
there's no other undecided hunk in either direction.

Reported-by: Windl, Ulrich <u.windl@ukr.de>
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-add.adoc

@@ -342,7 +342,7 @@ patch::
        d - do not stage this hunk or any of the later hunks in the file
        g - select a hunk to go to
        / - search for a hunk matching the given regex
-       j - go to the next undecided hunk
+       j - go to the next undecided hunk, roll over at the bottom
        J - go to the next hunk, roll over at the bottom
        k - go to the previous undecided hunk
        K - go to the previous hunk

add-patch.c

@@ -1397,7 +1397,7 @@ static size_t display_hunks(struct add_p_state *s,
 }
 
 static const char help_patch_remainder[] =
-N_("j - go to the next undecided hunk\n"
+N_("j - go to the next undecided hunk, roll over at the bottom\n"
    "J - go to the next hunk, roll over at the bottom\n"
    "k - go to the previous undecided hunk\n"
    "K - go to the previous hunk\n"
@@ -1408,6 +1408,11 @@ N_("j - go to the next undecided hunk\n"
    "p - print the current hunk, 'P' to use the pager\n"
    "? - print help\n");
 
+static size_t inc_mod(size_t a, size_t m)
+{
+	return a < m - 1 ? a + 1 : 0;
+}
+
 static int patch_update_file(struct add_p_state *s,
 			     struct file_diff *file_diff)
 {
@@ -1451,7 +1456,9 @@ static int patch_update_file(struct add_p_state *s,
 					break;
 				}
 
-			for (i = hunk_index + 1; i < file_diff->hunk_nr; i++)
+			for (i = inc_mod(hunk_index, file_diff->hunk_nr);
+			     i != hunk_index;
+			     i = inc_mod(i, file_diff->hunk_nr))
 				if (file_diff->hunk[i].use == UNDECIDED_HUNK) {
 					undecided_next = i;
 					break;
@@ -1594,7 +1601,7 @@ soft_increment:
 			if (permitted & ALLOW_GOTO_NEXT_UNDECIDED_HUNK)
 				hunk_index = undecided_next;
 			else
-				err(s, _("No next hunk"));
+				err(s, _("No other undecided hunk"));
 		} else if (s->answer.buf[0] == 'g') {
 			char *pend;
 			unsigned long response;

t/t3701-add-interactive.sh

@@ -1364,4 +1364,26 @@ test_expect_success 'option J rolls over' '
 	test_cmp expect actual
 '
 
+test_expect_success 'options y, n, j, e roll over to next undecided (1)' '
+	test_write_lines a b c d e f g h i j k l m n o p q >file &&
+	git add file &&
+	test_write_lines X b c d e f g h X j k l m n o p X >file &&
+	test_set_editor : &&
+	test_write_lines g3 y g3 n g3 j g3 e q | git add -p >out &&
+	test_write_lines 1  3 1  3 1  3 1  3 1 >expect &&
+	sed -n -e "s-/.*--" -e "s/^(//p" <out >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'options y, n, j, e roll over to next undecided (2)' '
+	test_write_lines a b c d e f g h i j k l m n o p q >file &&
+	git add file &&
+	test_write_lines X b c d e f g h X j k l m n o p X >file &&
+	test_set_editor : &&
+	test_write_lines y g3 y g3 n g3 j g3 e q | git add -p >out &&
+	test_write_lines 1 2  3 2  3 2  3 2  3 2 >expect &&
+	sed -n -e "s-/.*--" -e "s/^(//p" <out >actual &&
+	test_cmp expect actual
+'
+
 test_done