From owner-freebsd-hackers Wed Oct 16 4:15: 9 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id A5C0C37B401; Wed, 16 Oct 2002 04:15:08 -0700 (PDT) Received: from chiark.greenend.org.uk (chiark.greenend.org.uk [212.135.138.206]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5CA6C43EB3; Wed, 16 Oct 2002 04:15:07 -0700 (PDT) (envelope-from fanf@chiark.greenend.org.uk) Received: from fanf by chiark.greenend.org.uk with local (Exim 3.12 #1) id 181m8d-00029Y-00 (Debian); Wed, 16 Oct 2002 12:14:55 +0100 Date: Wed, 16 Oct 2002 12:14:55 +0100 From: Tony Finch To: Terry Lambert Cc: Tony Finch , Bruce Evans , Craig Rodrigues , freebsd-standards@FreeBSD.ORG, freebsd-hackers@FreeBSD.ORG Subject: Re: Problem detecting POSIX symbolic constants Message-ID: <20021016121455.A3711@chiark.greenend.org.uk> References: <20021012171803.F15910-100000@gamplex.bde.org> <3DA7E0F4.5988CA77@mindspring.com> <20021012151336.A24868@chiark.greenend.org.uk> <3DA883F2.33E84C@mindspring.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <3DA883F2.33E84C@mindspring.com>; from tlambert2@mindspring.com on Sat, Oct 12, 2002 at 01:20:03PM -0700 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Sat, Oct 12, 2002 at 01:20:03PM -0700, Terry Lambert wrote: > Tony Finch wrote: > > > > No -- the short-circuiting behaviour of && and || only matters if > > you can have side-effects, which you can't in the preprocessor, > > so there is no need to implement it (unifdef doesn't). > > Consider: > > #if _DEFINED_SUPPORTED && defined(SOMETHING) That's a syntax error in pre-ANSI preprocessors (unless defined() is #defined), which won't be bypassed by evaluation shortcutting since evaluation happens after parsing. Tony. -- f.a.n.finch http://dotat.at/ SOUTH BISCAY: SOUTHWEST 6 TO GALE 8 VEERING NORTHWEST 5 OR 6. RAIN OR THUNDERY SHOWERS. MODERATE OR GOOD. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message