Date: Mon, 8 Sep 2014 09:29:54 -0700 From: yaneurabeya@gmail.com To: Warner Losh <imp@bsdimp.com> Cc: Julio Merino <jmmv@freebsd.org>, "rpaulo@freebsd.org" <rpaulo@freebsd.org>, "freebsd-arch@FreeBSD.org Arch" <freebsd-arch@freebsd.org> Subject: Re: [RFC] Add __arraycount from NetBSD to sys/cdefs.h Message-ID: <146C3E96-7461-4D30-8B7F-5E20F72CF061@gmail.com> In-Reply-To: <8D279BDC-7D40-4750-8DA7-A4535DD2E458@bsdimp.com> References: <CAGHfRMBMPra5YXDn0e83dpVxwnarg3DL8o31xr7DhWv%2BVXskTg@mail.gmail.com> <8D279BDC-7D40-4750-8DA7-A4535DD2E458@bsdimp.com>
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On Sep 3, 2014, at 21:17, Warner Losh <imp@bsdimp.com> wrote:
> On Sep 3, 2014, at 9:45 PM, Garrett Cooper <yaneurabeya@gmail.com> =
wrote:
>=20
>> Hi all,
>> In order to ease porting code and reduce divergence with NetBSD
>> when importing code (a large chunk of which for me are tests), I =
would
>> like to move nitems to sys/cdefs.h and alias __arraycount to nitems.
>> Here's the __arraycount #define in lib/libnetbsd/sys/cdefs.h:
>>=20
>> 44 /*
>> 45 * Return the number of elements in a statically-allocated array,
>> 46 * __x.
>> 47 */
>> 48 #define __arraycount(__x) (sizeof(__x) / sizeof(__x[0]))
>>=20
>> Here's the nitems #define in sys/sys/param.h:
>>=20
>> 277 #define nitems(x) (sizeof((x)) / sizeof((x)[0]))
>>=20
>> sys/cdefs.h gets pulled in automatically with sys/param.h, so
>> anything using nitems will continue to function like before (see =
below
>> for more details). I've attached a patch which addresses all =
hardcoded
>> definitions in the tree added by FreeBSD developers.
>> If there aren't any major concerns with my proposed change, I'll
>> put it up for review on Phabricator.
>> Thank you!
>> -Garrett
>>=20
>> $ cat cdefs_pound_define.c
>> #include <sys/param.h>
>>=20
>> #ifdef _SYS_CDEFS_H_
>> #warning "sys/cdefs.h has been included"
>> #endif
>> $ cc -c cdefs_pound_define.c
>> cdefs_pound_define.c:4:2: warning: "sys/cdefs.h has been included" =
[-W#warnings]
>> #warning "sys/cdefs.h has been included"
>> ^
>> 1 warning generated.
>> $ cc -D_KERNEL -c cdefs_pound_define.c
>> cdefs_pound_define.c:4:2: warning: "sys/cdefs.h has been included" =
[-W#warnings]
>> #warning "sys/cdefs.h has been included"
>> ^
>> 1 warning generated.
>> $ gcc -c cdefs_pound_define.c
>> cdefs_pound_define.c:4:2: warning: #warning "sys/cdefs.h has been =
included"
>> $ gcc -D_KERNEL -c cdefs_pound_define.c
>> cdefs_pound_define.c:4:2: warning: #warning "sys/cdefs.h has been =
included=94
>=20
> I wouldn=92t bother changing the nitems #define. There=92s no need, =
really, to do that.
Rethinking my proposal, I agree. I had lofty hopes for unifying the =
macros, but the functional duplication (1 line) is harmless.
> I=92d also be more inclined to believe the test if you tested what the =
thing does rather than test for an artificial, implementation defined =
side effect.
Sure. I provided a lazy proof instead of a full proof :).
> But honestly the amount of duplication saved here is rather tiny=85
Indeed! Thank you for the input :) =97 I=92ve attached a new patch which =
doesn=92t disturb nitems or sys/param.h.
Thanks!
-Garrett
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