Date: Wed, 25 Feb 2026 09:52:00 -0800 From: "Enji Cooper (yaneurabeya)" <yaneurabeya@gmail.com> To: Vladimir Kondratyev <wulf@FreeBSD.org> Cc: "src-committers@freebsd.org" <src-committers@FreeBSD.org>, "dev-commits-src-all@freebsd.org" <dev-commits-src-all@FreeBSD.org>, "dev-commits-src-main@freebsd.org" <dev-commits-src-main@FreeBSD.org> Subject: Re: git: 64dab63f3b3b - main - LinuxKPI: Use negative bit field size to trigger BUILD_BUG_ON_ZERO Message-ID: <241DCDC1-B8A5-43CF-9FAA-19406EB8A996@gmail.com> In-Reply-To: <202201101950.20AJor0m009372@gitrepo.freebsd.org>
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> On Jan 10, 2022, at 11:50 AM, Vladimir Kondratyev <wulf@FreeBSD.org> wrote: > > The branch main has been updated by wulf: > > URL: https://cgit.FreeBSD.org/src/commit/?id=64dab63f3b3b6c6a1f8a92f43bed0aa28319d627 > > commit 64dab63f3b3b6c6a1f8a92f43bed0aa28319d627 > Author: Vladimir Kondratyev <wulf@FreeBSD.org> > AuthorDate: 2021-12-25 18:42:15 +0000 > Commit: Vladimir Kondratyev <wulf@FreeBSD.org> > CommitDate: 2022-01-10 19:49:38 +0000 > > LinuxKPI: Use negative bit field size to trigger BUILD_BUG_ON_ZERO > > compile time assertion on non-NULL pointers. Tests conducted show that > _Static_assert, negative array size method and current code does not > handle pointers well enough. Bit field method solves this problem. > > This change is derrived from Linux implementation of BUILD_BUG_ON_ZERO. > > MFC after: 1 week > Differential Revision: https://reviews.freebsd.org/D33674 > --- > sys/compat/linuxkpi/common/include/linux/kernel.h | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/sys/compat/linuxkpi/common/include/linux/kernel.h b/sys/compat/linuxkpi/common/include/linux/kernel.h > index 419dae214396..a84f577dd912 100644 > --- a/sys/compat/linuxkpi/common/include/linux/kernel.h > +++ b/sys/compat/linuxkpi/common/include/linux/kernel.h > @@ -109,9 +109,7 @@ > #define BUILD_BUG_ON_MSG(x, msg) BUILD_BUG_ON(x) > #define BUILD_BUG_ON_NOT_POWER_OF_2(x) BUILD_BUG_ON(!powerof2(x)) > #define BUILD_BUG_ON_INVALID(expr) while (0) { (void)(expr); } > - > -extern const volatile int lkpi_build_bug_on_zero; > -#define BUILD_BUG_ON_ZERO(x) ((x) ? lkpi_build_bug_on_zero : 0) > +#define BUILD_BUG_ON_ZERO(x) ((int)sizeof(struct { int:-((x) != 0); })) Hi Vladimir, I think this change is causing build problems now with gcc14. Please see the snippet from https://ci.freebsd.org/job/FreeBSD-main-amd64-gcc14_build/2986/consoleText below. Thanks, -Enji --- all_subdir_rtw89 --- --- core.o --- In file included from /workspace/src/sys/compat/linuxkpi/common/include/linux/kernel.h:44, from /workspace/src/sys/compat/linuxkpi/common/include/linux/skbuff.h:39, from /workspace/src/sys/compat/linuxkpi/common/include/linux/ip.h:40, from /workspace/src/sys/contrib/dev/rtw89/core.c:9: /workspace/src/sys/contrib/dev/rtw89/core.c: In function 'rtw89_bcn_calc_drift': /workspace/src/sys/compat/linuxkpi/common/include/linux/build_bug.h:60:33: error: statement with no effect [-Werror=unused-value] 60 | #define BUILD_BUG_ON_ZERO(x) ((int)sizeof(struct { int:-((x) != 0); })) | ^ /workspace/src/sys/compat/linuxkpi/common/include/linux/sort.h:37:9: note: in expansion of macro 'BUILD_BUG_ON_ZERO' 37 | BUILD_BUG_ON_ZERO(swap); \ | ^~~~~~~~~~~~~~~~~ /workspace/src/sys/contrib/dev/rtw89/core.c:2575:9: note: in expansion of macro 'sort' 2575 | sort(drift, RTW89_BCN_TRACK_STAT_NR, sizeof(*drift), cmp_u16, NULL); | ^~~~home | help
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