Date: Wed, 16 Oct 2002 12:14:55 +0100 From: Tony Finch <dot@dotat.at> To: Terry Lambert <tlambert2@mindspring.com> Cc: Tony Finch <dot@dotat.at>, Bruce Evans <bde@zeta.org.au>, Craig Rodrigues <rodrigc@attbi.com>, freebsd-standards@FreeBSD.ORG, freebsd-hackers@FreeBSD.ORG Subject: Re: Problem detecting POSIX symbolic constants Message-ID: <20021016121455.A3711@chiark.greenend.org.uk> In-Reply-To: <3DA883F2.33E84C@mindspring.com>; from tlambert2@mindspring.com on Sat, Oct 12, 2002 at 01:20:03PM -0700 References: <20021012171803.F15910-100000@gamplex.bde.org> <3DA7E0F4.5988CA77@mindspring.com> <20021012151336.A24868@chiark.greenend.org.uk> <3DA883F2.33E84C@mindspring.com>
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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 <dot@dotat.at> 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
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