From: Phillip Wood <phillip.wood123@gmail.com>
To: Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>,
git@vger.kernel.org
Cc: Johannes Schindelin <johannes.schindelin@gmx.de>
Subject: Re: [PATCH 4/5] add -p: avoid ambiguous signed/unsigned comparison
Date: Thu, 11 Aug 2022 13:49:19 +0100 [thread overview]
Message-ID: <ec8204d5-9d0d-9850-f930-6fc1a8efacc5@gmail.com> (raw)
In-Reply-To: <4d24a4345ba66031d2ccf7ce472ed93ace82e9d6.1660143750.git.gitgitgadget@gmail.com>
Hi Dscho
On 10/08/2022 16:02, Johannes Schindelin via GitGitGadget wrote:
> From: Johannes Schindelin <johannes.schindelin@gmx.de>
>
> In the interactive `add` operation, users can choose to jump to specific
> hunks, and Git will present the hunk list in that case. To avoid showing
> too many lines at once, only a maximum of 21 hunks are shown, skipping
> the "mode change" pseudo hunk.
>
> The comparison performed to skip the "mode change" pseudo hunk (if any)
> compares a signed integer `i` to the unsigned value `mode_change` (which
> can be 0 or 1 because it is a 1-bit type).
>
> According to section 6.3.1.8 of the C99 standard (see e.g.
> https://www.open-std.org/jtc1/sc22/WG14/www/docs/n1256.pdf), what should
> happen is an automatic conversion of the "lesser" type to the "greater"
> type, but since the types differ in signedness, it is ill-defined what
> is the correct "usual arithmetic conversion".
>
> Which means that Visual C's behavior can (and does) differ from GCC's:
> When compiling Git using the latter, `add -p`'s `goto` command shows no
> hunks by default because it casts a negative start offset to a pretty
> large unsigned value, breaking the "goto hunk" test case in
> `t3701-add-interactive.sh`.
>
> Let's avoid that by converting the unsigned bit explicitly to a signed
> integer.
Oh the joys of bit-fields!
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
> add-patch.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/add-patch.c b/add-patch.c
> index 509ca04456b..3524555e2b0 100644
> --- a/add-patch.c
> +++ b/add-patch.c
> @@ -1547,7 +1547,7 @@ soft_increment:
> strbuf_remove(&s->answer, 0, 1);
> strbuf_trim(&s->answer);
Unrelated to this change but why don't we just call strbuf_reset() here?
> i = hunk_index - DISPLAY_HUNKS_LINES / 2;
> - if (i < file_diff->mode_change)
> + if (i < (int)file_diff->mode_change)
The change itself looks good
Best Wishes
Phillip
> i = file_diff->mode_change;
> while (s->answer.len == 0) {
> i = display_hunks(s, file_diff, i);
next prev parent reply other threads:[~2022-08-11 12:49 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-10 15:02 [PATCH 0/5] Some fixes and an improvement for using CTest on Windows Johannes Schindelin via GitGitGadget
2022-08-10 15:02 ` [PATCH 1/5] cmake: align CTest definition with Git's CI runs Johannes Schindelin via GitGitGadget
2022-08-10 17:48 ` Junio C Hamano
2022-08-16 10:11 ` Johannes Schindelin
2022-08-16 15:15 ` Junio C Hamano
2022-08-19 13:57 ` Johannes Schindelin
2022-08-11 11:18 ` Ævar Arnfjörð Bjarmason
2022-08-10 15:02 ` [PATCH 2/5] cmake: copy the merge tools for testing Johannes Schindelin via GitGitGadget
2022-08-10 15:02 ` [PATCH 3/5] tests: explicitly skip `chmod` calls on Windows Johannes Schindelin via GitGitGadget
2022-08-11 11:22 ` Ævar Arnfjörð Bjarmason
2022-08-22 10:19 ` Johannes Schindelin
2022-08-23 7:34 ` Johannes Schindelin
2022-08-10 15:02 ` [PATCH 4/5] add -p: avoid ambiguous signed/unsigned comparison Johannes Schindelin via GitGitGadget
2022-08-10 17:54 ` Junio C Hamano
2022-08-16 9:56 ` Johannes Schindelin
2022-08-16 15:10 ` Junio C Hamano
2022-08-19 14:52 ` Johannes Schindelin
2022-08-11 12:49 ` Phillip Wood [this message]
2022-08-16 10:00 ` Johannes Schindelin
2022-08-16 14:23 ` Phillip Wood
2022-08-19 14:07 ` Johannes Schindelin
2022-08-10 15:02 ` [PATCH 5/5] cmake: avoid editing t/test-lib.sh Johannes Schindelin via GitGitGadget
2022-08-11 11:35 ` Ævar Arnfjörð Bjarmason
2022-10-18 14:02 ` Johannes Schindelin
2022-08-11 12:58 ` Phillip Wood
2022-08-16 10:09 ` Johannes Schindelin
2022-08-16 14:27 ` Phillip Wood
2022-08-23 8:30 ` [PATCH v2 0/5] Some fixes and an improvement for using CTest on Windows Johannes Schindelin via GitGitGadget
2022-08-23 8:30 ` [PATCH v2 1/5] cmake: make it easier to diagnose regressions in CTest runs Johannes Schindelin via GitGitGadget
2022-09-07 22:10 ` Victoria Dye
2022-10-18 14:02 ` Johannes Schindelin
2022-09-08 7:22 ` Ævar Arnfjörð Bjarmason
2022-09-28 6:55 ` Eric Sunshine
2022-08-23 8:31 ` [PATCH v2 2/5] cmake: copy the merge tools for testing Johannes Schindelin via GitGitGadget
2022-08-23 8:31 ` [PATCH v2 3/5] add -p: avoid ambiguous signed/unsigned comparison Johannes Schindelin via GitGitGadget
2022-08-23 8:31 ` [PATCH v2 4/5] cmake: avoid editing t/test-lib.sh Johannes Schindelin via GitGitGadget
2022-09-08 7:39 ` Ævar Arnfjörð Bjarmason
2022-10-18 14:03 ` Johannes Schindelin
2022-10-18 15:09 ` Ævar Arnfjörð Bjarmason
2022-09-08 23:37 ` Victoria Dye
2022-09-08 23:42 ` Victoria Dye
2022-09-08 23:58 ` Junio C Hamano
2022-10-18 14:03 ` Johannes Schindelin
2022-08-23 8:31 ` [PATCH v2 5/5] cmake: increase time-out for a long-running test Johannes Schindelin via GitGitGadget
2022-09-08 7:34 ` Ævar Arnfjörð Bjarmason
2022-09-08 17:29 ` Victoria Dye
2022-09-08 3:51 ` [PATCH v2 0/5] Some fixes and an improvement for using CTest on Windows Victoria Dye
2022-10-18 10:59 ` [PATCH v3 " Johannes Schindelin via GitGitGadget
2022-10-18 10:59 ` [PATCH v3 1/5] cmake: make it easier to diagnose regressions in CTest runs Johannes Schindelin via GitGitGadget
2022-10-18 13:41 ` Ævar Arnfjörð Bjarmason
2022-10-18 10:59 ` [PATCH v3 2/5] cmake: copy the merge tools for testing Johannes Schindelin via GitGitGadget
2022-10-18 13:49 ` Ævar Arnfjörð Bjarmason
2022-10-18 10:59 ` [PATCH v3 3/5] add -p: avoid ambiguous signed/unsigned comparison Johannes Schindelin via GitGitGadget
2022-10-18 13:53 ` Ævar Arnfjörð Bjarmason
2022-10-18 10:59 ` [PATCH v3 4/5] cmake: avoid editing t/test-lib.sh Johannes Schindelin via GitGitGadget
2022-10-18 13:54 ` Ævar Arnfjörð Bjarmason
2022-10-18 14:21 ` Johannes Schindelin
2022-10-18 10:59 ` [PATCH v3 5/5] cmake: increase time-out for a long-running test Johannes Schindelin via GitGitGadget
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