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From: Jeff King <peff@peff•net>
To: Lidong Yan <yldhome2d2@gmail•com>
Cc: Junio C Hamano <gitster@pobox•com>,
	Jake Zimmerman <jake@zimmerman•io>,
	git@vger•kernel.org
Subject: Re: Regression in `git diff --quiet HEAD` when a new file is staged
Date: Wed, 22 Oct 2025 05:14:33 -0400	[thread overview]
Message-ID: <20251022091433.GC853931@coredump.intra.peff.net> (raw)
In-Reply-To: <E76C71D8-103E-4C37-B05C-86DC180BD519@gmail.com>

On Wed, Oct 22, 2025 at 12:46:55PM +0800, Lidong Yan wrote:

> Junio C Hamano <gitster@pobox•com> writes:
> > 
> > /* return 1 if any change is found; otherwise, return 0 */
> > static int diff_flush_patch_quietly(struct diff_filepair *p, struct diff_options *o)
> > {
> > @@ -6179,6 +6181,15 @@ static int diff_flush_patch_quietly(struct diff_filepair *p, struct diff_options
> > int saved_found_changes = o->found_changes;
> > int ret;
> > 
> > + /*
> > + * run diff_flush_patch for the exit status. setting
> > + * options->file to /dev/null should be safe, because we
> > + * aren't supposed to produce any output anyway.
> > + */
> > + diff_free_file(o);
> > + o->file = xfopen("/dev/null", "w");
> > + o->close_file = 1;
> > + o->color_moved = 0;
> > o->dry_run = 1;
> > o->found_changes = 0;
> > diff_flush_patch(p, o);
> > 
> 
> This would make everything going to "/dev/null" after the flush_quietly() call.
> I think we need to restore o->file.

We probably also need to restore o->color_moved, too.

In the long run (and this is the kind of cleanup I was hoping you'd work
on for 'master'), we probably could drop that line entirely and just
skip running the moved-line detection when dry_run is set. Assuming it
even runs at all. From a quick look at the code, it looks like we only
do color-moved handling via diff_flush_patch_all_file_pairs(), so it
wouldn't trigger at all for the cases that do individual calls to
diff_flush_patch_quietly()?

-Peff

  reply	other threads:[~2025-10-22  9:14 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-10-17  0:09 Regression in `git diff --quiet HEAD` when a new file is staged Jake Zimmerman
2025-10-17  7:51 ` Jeff King
2025-10-17  8:36   ` [PATCH] diff: restore redirection to /dev/null for diff_from_contents Jeff King
2025-10-17 18:22     ` Junio C Hamano
2025-10-19 21:09     ` Johannes Schindelin
2025-10-21  7:52       ` Jeff King
2025-10-17 11:44   ` Regression in `git diff --quiet HEAD` when a new file is staged Johannes Schindelin
2025-10-17 17:45   ` Junio C Hamano
2025-10-18  1:04     ` Lidong Yan
2025-10-18  9:42       ` Jeff King
2025-10-18  9:40     ` Jeff King
2025-10-18 15:23       ` Junio C Hamano
2025-10-21  7:36         ` Jeff King
2025-10-21 14:38           ` Junio C Hamano
2025-10-22  4:46             ` Lidong Yan
2025-10-22  9:14               ` Jeff King [this message]
2025-10-22 14:20                 ` Lidong Yan
2025-10-22 14:31               ` Junio C Hamano
2025-10-22 16:28                 ` Junio C Hamano
2025-10-22  9:11             ` Jeff King
2025-10-22 16:48               ` Junio C Hamano
2025-10-23 12:01                 ` Jeff King
2025-10-23 12:15                   ` Jeff King
2025-10-23 13:35                   ` Junio C Hamano
2025-10-22 17:39             ` Junio C Hamano
2025-10-23  0:33               ` Lidong Yan
2025-10-23 13:42                 ` Junio C Hamano

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