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From: "René Scharfe" <l.s.r@web•de>
To: Junio C Hamano <gitster@pobox•com>
Cc: "Windl, Ulrich" <u.windl@ukr•de>,
	"git@vger•kernel.org" <git@vger•kernel.org>
Subject: Re: [PATCH] add-patch: roll over to next undecided hunk
Date: Fri, 3 Oct 2025 21:53:00 +0200	[thread overview]
Message-ID: <737e78f5-6337-4964-8385-9c35897f5dff@web.de> (raw)
In-Reply-To: <xmqqo6qoufqp.fsf@gitster.g>

On 10/3/25 6:11 PM, Junio C Hamano wrote:
> René Scharfe <l.s.r@web•de> writes:
> 
>> git add --patch presents diff hunks one after the other, asking whether
>> to add them.  If we mark some as undecided, e.g. with J, then it will
> 
> Perhaps "mark" -> "leave".
> 
> I somehow find it awkward to say "mark as undecided", as I have
> always viewed J/K as a way to skip a hunk, leaving it undecided.
> 
> Besides, "J" lets you revisit a hunk that you earlier have decided
> to use of hold off, and it leaves your last decision on that hunk.
> A statement that implies "J marks as undecided" is misleading.

Right, j/J/k/K leave the use/skip/undecided status of the current hunk
unchanged.  "leave this hunk undecided" in the documentation is
misleading as well, because these options will not leave a hunk
undecided if we made a decision on it before:

               j - leave this hunk undecided, see next undecided hunk
               J - leave this hunk undecided, see next hunk
               k - leave this hunk undecided, see previous undecided hunk
               K - leave this hunk undecided, see previous hunk

Perhaps omit it?

               j - go to next undecided hunk
               J - go to next hunk
               k - go to previous undecided hunk
               K - go to previous hunk

Weird that one can switch between use and skip, but there's no
way to revert back to undecided.

>> start over after reaching the last hunk.  It always starts over at the
>> very first hunk, though, even if we already decided on it.  Skip
>> decided hunks when rolling over instead.
> 
> Nicely analyzed.
> 
>> Reported-by: Windl, Ulrich <u.windl@ukr•de>
>> Signed-off-by: René Scharfe <l.s.r@web•de>
>> ---
>>  add-patch.c                |  9 ++++++++-
>>  t/t3701-add-interactive.sh | 20 ++++++++++++++++++++
>>  2 files changed, 28 insertions(+), 1 deletion(-)
>>
>> diff --git a/add-patch.c b/add-patch.c
>> index b0389c5d5b..42a8394c92 100644
>> --- a/add-patch.c
>> +++ b/add-patch.c
>> @@ -1436,8 +1436,15 @@ static int patch_update_file(struct add_p_state *s,
>>  	render_diff_header(s, file_diff, colored, &s->buf);
>>  	fputs(s->buf.buf, stdout);
>>  	for (;;) {
>> -		if (hunk_index >= file_diff->hunk_nr)
>> +		if (hunk_index >= file_diff->hunk_nr) {
>>  			hunk_index = 0;
>> +			for (i = 0; i < file_diff->hunk_nr; i++) {
>> +				if (file_diff->hunk[i].use == UNDECIDED_HUNK) {
>> +					hunk_index = i;
>> +					break;
>> +				}
>> +			}
>> +		}
> 
> OK.
> 
> This is probably a closely related tangent, but last night I was
> looking this function and found that its per-hunk loop does
> completely bogus thing.  For example, find a case where you have
> more than one hunks, among which there are splittable and
> non-splittable hunks (a hunk is splittable if there are context
> lines between an added or a removed line).  Start cycling the hunks
> without making any decisions with "J" or "K".  Once you visited a
> splittable hunk (where you'd see 's' among the possible choices),
> coming back to an unsplittable hunk will now let you split it!  's'
> may not be visible among the choices, but telling it to 's'plit will
> give you "Split into 1", which is a technically correct nonsense.
> 
> This is because the handling of "permitted" in that function only
> adds, without resetting at the end of processing the current hunk.
> Yet it does something like this:
> 
> 	for (;;) {
> 		...
> 		strbuf_reset(&s->buf);
> 		if (file_diff->hunk_nr) {
> 			... add choices to the prompt ...
> 			if (hunk->splittable_into > 1) {
> 				permitted |= ALLOW_SPLIT;
> 				strbuf_addstr(&s->buf, ",s");
> 			}
> 			...
> 		}
> 		...
> 		printf(_(s->mode->prompt_mode[prompt_mode_type]),
> 		       s->buf.buf);
> 		if (*s->s.reset_color_interactive)
> 			fputs(s->s.reset_color_interactive, stdout);
> 		fflush(stdout);
> 		if (read_single_character(s) == EOF)
> 			break;
> 		ch = tolower(s->answer.buf[0]);
> 		... dispatch on the command character ...
> 		if (ch == 'y') {
> 			...
> 		} else if (s->answer.buf[0] == 's') {
> 			size_t splittable_into = hunk->splittable_into;
> 			if (!(permitted & ALLOW_SPLIT)) {
> 				err(s, _("Sorry, cannot split this hunk"));
> 			} else if (!split_hunk(s, file_diff,
> 					     hunk - file_diff->hunk)) {
> 				color_fprintf_ln(stdout, s->s.header_color,
> 						 _("Split into %d hunks."),
> 						 (int)splittable_into);
> 				rendered_hunk_index = -1;
> 			}
> 		...
> 
> Notice that the prompt is built correctly but that information is
> *not* used when deciding if the operation is possible?
> 
> This is another ancient regression that was introduced while
> rewriting this program in C near the end of 2019, I think.  And this
> causes many other bugs in this area, like 'k' at the very first hunk
> gets complaint "No previous hunk" only once (you move to the next
> one with 'j' and come back to the first hunk with 'k', and then 'k'
> no longer complains, even though it is not among the choice).

This should be easy to fix by resetting permitted at the start of the
loop, no?  Patch below.

> With this bug, however, we have gained a bit of useful feature, I
> think.  Even though j/J should not be offered when we are at the
> last hunk for a file, we do wrap-around to the first hunk.  I just
> checked the original code before the C rewrite, and even though it
> were written defensively so that incrementing the current hunk
> number to 5 when you have only 4 hunks would take you back to the
> initial hunk (instead of barfing), because we did not have this
> "permitted is never reset" bug, it actually did not allow you to go
> beyond the end with j/J.  Today's code seems to have inherited this
> defensive adjustment to stay within the available hunks, and with
> the "permitted is never reset" bug, we are taken back to the first
> hunk.
y/n/e on the last hunk roll over, which makes sense to me.  Their
movement part is not mentioned in the documentation, by the way.

With the patch below j/J are stopped by the floor, as seemingly
intended.  Not sure if the (now accidental) roll-over behavior is
better for them.


 add-patch.c                | 19 ++++++++++---------
 t/t3701-add-interactive.sh | 19 +++++++++++++++++++
 2 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/add-patch.c b/add-patch.c
index 42a8394c92..1012840019 100644
--- a/add-patch.c
+++ b/add-patch.c
@@ -1418,15 +1418,6 @@ static int patch_update_file(struct add_p_state *s,
 	struct child_process cp = CHILD_PROCESS_INIT;
 	int colored = !!s->colored.len, quit = 0, use_pager = 0;
 	enum prompt_mode_type prompt_mode_type;
-	enum {
-		ALLOW_GOTO_PREVIOUS_HUNK = 1 << 0,
-		ALLOW_GOTO_PREVIOUS_UNDECIDED_HUNK = 1 << 1,
-		ALLOW_GOTO_NEXT_HUNK = 1 << 2,
-		ALLOW_GOTO_NEXT_UNDECIDED_HUNK = 1 << 3,
-		ALLOW_SEARCH_AND_GOTO = 1 << 4,
-		ALLOW_SPLIT = 1 << 5,
-		ALLOW_EDIT = 1 << 6
-	} permitted = 0;
 
 	/* Empty added files have no hunks */
 	if (!file_diff->hunk_nr && !file_diff->added)
@@ -1436,6 +1427,16 @@ static int patch_update_file(struct add_p_state *s,
 	render_diff_header(s, file_diff, colored, &s->buf);
 	fputs(s->buf.buf, stdout);
 	for (;;) {
+		enum {
+			ALLOW_GOTO_PREVIOUS_HUNK = 1 << 0,
+			ALLOW_GOTO_PREVIOUS_UNDECIDED_HUNK = 1 << 1,
+			ALLOW_GOTO_NEXT_HUNK = 1 << 2,
+			ALLOW_GOTO_NEXT_UNDECIDED_HUNK = 1 << 3,
+			ALLOW_SEARCH_AND_GOTO = 1 << 4,
+			ALLOW_SPLIT = 1 << 5,
+			ALLOW_EDIT = 1 << 6
+		} permitted = 0;
+
 		if (hunk_index >= file_diff->hunk_nr) {
 			hunk_index = 0;
 			for (i = 0; i < file_diff->hunk_nr; i++) {
diff --git a/t/t3701-add-interactive.sh b/t/t3701-add-interactive.sh
index fa6ec5f835..33b307b8ff 100755
--- a/t/t3701-add-interactive.sh
+++ b/t/t3701-add-interactive.sh
@@ -1341,6 +1341,25 @@ test_expect_success 'roll over to next undecided (2)' '
 	test_cmp expect hunks
 '
 
+test_expect_success 'invalid options are rejected' '
+	test_write_lines a b c d e f g h i j k >file &&
+	git add file &&
+	test_write_lines X b c d e f g h X j X >file &&
+	test_write_lines j j J k k K s q | git add -p >out &&
+	sed -ne "s/ @@.*//" -e "s/ \$//" -e "/^(/p" <out >actual &&
+	cat >expect <<-EOF &&
+	(1/2) Stage this hunk [y,n,q,a,d,j,J,g,/,e,p,?]?
+	(2/2) Stage this hunk [y,n,q,a,d,k,K,g,/,s,e,p,?]? No next hunk
+	(2/2) Stage this hunk [y,n,q,a,d,k,K,g,/,s,e,p,?]? No next hunk
+	(2/2) Stage this hunk [y,n,q,a,d,k,K,g,/,s,e,p,?]?
+	(1/2) Stage this hunk [y,n,q,a,d,j,J,g,/,e,p,?]? No previous hunk
+	(1/2) Stage this hunk [y,n,q,a,d,j,J,g,/,e,p,?]? No previous hunk
+	(1/2) Stage this hunk [y,n,q,a,d,j,J,g,/,e,p,?]? Sorry, cannot split this hunk
+	(1/2) Stage this hunk [y,n,q,a,d,j,J,g,/,e,p,?]?
+	EOF
+	test_cmp expect actual
+'
+
 test_expect_success 'set up base for -p color tests' '
 	echo commit >file &&
 	git commit -am "commit state" &&


  reply	other threads:[~2025-10-03 19:58 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-10-02  9:23 Broken handling of "J" hunks for "add --interactive"? Windl, Ulrich
2025-10-03 12:16 ` [PATCH] add-patch: roll over to next undecided hunk René Scharfe
2025-10-03 13:41   ` Phillip Wood
2025-10-03 14:10     ` René Scharfe
2025-10-08 13:47       ` Phillip Wood
2025-10-03 16:11   ` Junio C Hamano
2025-10-03 19:53     ` René Scharfe [this message]
2025-10-03 20:39       ` Junio C Hamano
2025-10-03 20:42       ` Junio C Hamano
2025-10-03 21:18   ` Junio C Hamano
2025-10-05 15:45 ` [PATCH v2 0/5] " René Scharfe
2025-10-05 15:55   ` [PATCH v2 1/5] add-patch: improve help for options j, J, k, and K René Scharfe
2025-10-05 21:30     ` Junio C Hamano
2025-10-06 17:17       ` René Scharfe
2025-10-06 17:58         ` Junio C Hamano
2025-10-31 10:08     ` [EXT] " Windl, Ulrich
2025-11-01  8:18       ` Junio C Hamano
2025-11-03 12:43         ` [EXT] " Windl, Ulrich
2025-10-05 15:55   ` [PATCH v2 2/5] add-patch: document that option J rolls over René Scharfe
2025-10-05 21:30     ` Junio C Hamano
2025-10-05 15:55   ` [PATCH v2 3/5] add-patch: let options y, n, j, and e roll over to next undecided René Scharfe
2025-10-05 15:55   ` [PATCH v2 4/5] add-patch: let options k and K roll over like j and J René Scharfe
2025-10-05 20:55     ` Junio C Hamano
2025-10-06 17:18       ` René Scharfe
2025-10-05 15:55   ` [PATCH v2 5/5] add-patch: reset "permitted" at loop start René Scharfe
2025-10-06 17:18 ` [PATCH v3 0/6] add-patch: roll over to next undecided hunk René Scharfe
2025-10-06 17:19   ` [PATCH v3 1/6] add-patch: improve help for options j, J, k, and K René Scharfe
2025-10-06 17:20   ` [PATCH v3 2/6] add-patch: document that option J rolls over René Scharfe
2025-10-06 17:21   ` [PATCH v3 3/6] add-patch: let options y, n, j, and e roll over to next undecided René Scharfe
2025-10-06 17:22   ` [PATCH v3 4/6] add-patch: let options k and K roll over like j and J René Scharfe
2025-10-06 17:23   ` [PATCH v3 5/6] add-patch: let options a and d roll over like y and n René Scharfe
2025-10-06 17:24   ` [PATCH v3 6/6] add-patch: reset "permitted" at loop start René Scharfe
2025-10-31 10:28     ` [EXT] " Windl, Ulrich
2025-10-31 15:16       ` Junio C Hamano
2025-10-06 18:00   ` [PATCH v3 0/6] add-patch: roll over to next undecided hunk Junio C Hamano
2025-10-06 20:05     ` René Scharfe
2025-10-06 22:01       ` Junio C Hamano

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