Received-SPF: pass (google.com: domain of linux-kernel+bounces-134082-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Content-Type: text/plain;
	charset=utf-8
Precedence: bulk
Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3774.500.171.1.1\))
Subject: Re: [PATCH] bcachefs: Rename struct field swap to prevent macro
 naming collision
From: Thorsten Blum <thorsten.blum@toblux.com>
In-Reply-To: <wvui43l6pcfexoglhyy4xfdjs4mrjzmbcwupnb4djlgvrebn7s@l22gudock5d6>
Date: Sat, 6 Apr 2024 23:21:37 +0200
Cc: Brian Foster <bfoster@redhat.com>,
 linux-bcachefs@vger.kernel.org,
 linux-kernel@vger.kernel.org
Content-Transfer-Encoding: quoted-printable
Message-Id: <E5B1C1FA-0B85-49ED-8EE6-4F01FBA2AC99@toblux.com>
References: <20240406141919.248148-2-thorsten.blum@toblux.com>
 <wvui43l6pcfexoglhyy4xfdjs4mrjzmbcwupnb4djlgvrebn7s@l22gudock5d6>
To: Kent Overstreet <kent.overstreet@linux.dev>

On 6. Apr 2024, at 20:48, Kent Overstreet <kent.overstreet@linux.dev> =
wrote:
>=20
> On Sat, Apr 06, 2024 at 04:19:20PM +0200, Thorsten Blum wrote:
>> The struct field swap can collide with the swap() macro defined in
>> linux/minmax.h. Rename the struct field to prevent such collisions.
>=20
> Same as in lib/sort.c, so what's the actual reason?

I included <linux/minmax.h> in arch/m68k/include/asm/bitops.h (to use =
the min()
macro), but received the following error:

fs/bcachefs/eytzinger.c: In function =E2=80=98do_swap=E2=80=99:
fs/bcachefs/eytzinger.c:128:69: error: macro "swap" passed 3 arguments, =
but takes just 2
  128 |                 ((const struct wrapper *)priv)->swap(a, b, =
(int)size);
      |                                                                  =
   ^
In file included from ./arch/m68k/include/asm/bitops.h:16,
                 from ./include/linux/bitops.h:68,
                 from fs/bcachefs/eytzinger.h:5,
                 from fs/bcachefs/eytzinger.c:3:
/include/linux/minmax.h:270: note: macro "swap" defined here
  270 | #define swap(a, b) \
      |
fs/bcachefs/eytzinger.c:128:47: warning: statement with no effect =
[-Wunused-value]
  128 |                 ((const struct wrapper *)priv)->swap(a, b, =
(int)size);
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
make[4]: *** [scripts/Makefile.build:244: fs/bcachefs/eytzinger.o] Error =
1
make[3]: *** [scripts/Makefile.build:485: fs/bcachefs] Error 2

I thought about using #undef swap, but renaming it seemed to be the =
least
disruptive change. Maybe there's a better solution?

Thanks,
Thorsten=