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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,
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To: Mark Millard <markmi@dsl-only.net>
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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