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From: karl@haddock.UUCP (Karl Heuer)
Newsgroups: comp.lang.c
Subject: Re: draft ANSI standard: major, quiet, unnoticed change
Message-ID: <187@haddock.UUCP>
Date: Thu, 4-Dec-86 20:54:05 EST
Article-I.D.: haddock.187
Posted: Thu Dec  4 20:54:05 1986
Date-Received: Fri, 5-Dec-86 06:07:18 EST
References: <1379@hoptoad.uucp>
Reply-To: karl@haddock.ISC.COM.UUCP (Karl Heuer)
Organization: Interactive Systems, Boston
Lines: 19
Keywords: nonstandard predefined words
Summary: It can still be done

In article <1379@hoptoad.uucp> gnu@hoptoad.uucp (John Gilmore) writes:
>The new standard disallows an implementation's pre-#defining any words
>that don't begin with _ (section 3.8.8, "No macro names without a
>leading underscore shall be predefined.").  This breaks all the code
>that uses ["#ifdef vax", etc.]

I noticed this too, and wondered how we are expected to do architecture-
dependent conditional compilation in the future.  Perhaps the idea is to
use "#ifdef _vax", etc.

>One possible workaround is a set of configuration #define's which are only
>visible to #if and #ifdef, not to program code.  [Suggests "#pdefine vax"]

This would still break the letter of the proposal.  But if it's permitted,
it's not necessary to make a new #-word; since macros cannot be recursive,
"#define vax vax" will do.  I believe the old V6 cpp allowed this sort of
thing as a special case.

Karl W. Z. Heuer (ima!haddock!karl or karl@haddock.isc.com), The Walking Lint