From owner-freebsd-hackers@freebsd.org  Fri Aug 25 07:14:59 2017
Return-Path: <owner-freebsd-hackers@freebsd.org>
Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id 8C8ECDF1711;
 Fri, 25 Aug 2017 07:14:59 +0000 (UTC)
 (envelope-from theraven@FreeBSD.org)
Received: from theravensnest.org (xvm-110-62.dc2.ghst.net [46.226.110.62])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client CN "theravensnest.org",
 Issuer "Let's Encrypt Authority X3" (verified OK))
 by mx1.freebsd.org (Postfix) with ESMTPS id 2E146763B3;
 Fri, 25 Aug 2017 07:14:57 +0000 (UTC)
 (envelope-from theraven@FreeBSD.org)
Received: from [192.168.1.65] (host86-138-54-151.range86-138.btcentralplus.com
 [86.138.54.151]) (authenticated bits=0)
 by theravensnest.org (8.15.2/8.15.2) with ESMTPSA id v7P7EkFL066989
 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO);
 Fri, 25 Aug 2017 07:14:48 GMT (envelope-from theraven@FreeBSD.org)
X-Authentication-Warning: d60e724c-75b0-4b63-9702-f4a9d2bf6793: Host
 host86-138-54-151.range86-138.btcentralplus.com [86.138.54.151] claimed to be
 [192.168.1.65]
Content-Type: text/plain; charset=utf-8
Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\))
Subject: Re: svn commit: r322875 - head/sys/dev/nvme
From: David Chisnall <theraven@FreeBSD.org>
In-Reply-To: <1C5A448F-C91A-4599-8500-E4E46E6F5205@dsl-only.net>
Date: Fri, 25 Aug 2017 08:14:41 +0100
Cc: imp@FreeBSD.org, svn-src-head@freebsd.org,
 FreeBSD Current <freebsd-current@freebsd.org>,
 FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org>,
 freebsd-hackers <freebsd-hackers@freebsd.org>
Content-Transfer-Encoding: quoted-printable
Message-Id: <DCD7947D-DA37-4255-A147-4B9E3B1631ED@FreeBSD.org>
References: <1C5A448F-C91A-4599-8500-E4E46E6F5205@dsl-only.net>
To: Mark Millard <markmi@dsl-only.net>
X-Mailer: Apple Mail (2.3273)
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.23
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
 <freebsd-hackers.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-hackers>, 
 <mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers/>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-hackers>, 
 <mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 25 Aug 2017 07:14:59 -0000

On 25 Aug 2017, at 07:32, Mark Millard <markmi@dsl-only.net> wrote:
>=20
> As I remember _Static_assert is from C11, not
> the older C99.

In pre-C11 dialects of C, _Static_assert is an identifier reserved for =
the implementation.  sys/cdefs.h defines it to generate a zero-length =
array if the condition is true or a negative-length array if it is =
false, emulating the behaviour (though giving less helpful error =
messages)

>=20
> As I understand head/sys/dev/nvme/nvme.h use by
> C++ code could now reject attempts to use
> _Static_assert .

In C++, _Static_assert is an identifier reserved for the implementation, =
but in C++11 or newer static_assert is a keyword.  sys/cdefs.h defines =
_Static_assert to static_assert for newer versions of C++ and defines it =
to the C-before-11-compatible version for C++-before-11.

TL;DR: We have gone to a lot of effort to ensure that these keywords =
work in all C/C++ dialects, please use them, please report bugs if you =
find a case where they don=E2=80=99t work.

David