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Date:      Wed, 16 Oct 2002 09:32:13 -0700
From:      Terry Lambert <tlambert2@mindspring.com>
To:        Tony Finch <dot@dotat.at>
Cc:        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:  <3DAD948D.7705B38F@mindspring.com>
References:  <20021012171803.F15910-100000@gamplex.bde.org> <3DA7E0F4.5988CA77@mindspring.com> <20021012151336.A24868@chiark.greenend.org.uk> <3DA883F2.33E84C@mindspring.com> <20021016121455.A3711@chiark.greenend.org.uk>

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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.

No, it's implementation defined.

-- Terry

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