Date: Sat, 18 Nov 2000 09:20:02 -0800 (PST) From: Bruce Evans <bde@zeta.org.au> To: freebsd-bugs@FreeBSD.org Subject: Re: misc/22936: <stdbool.h> broken, needs repair Message-ID: <200011181720.JAA84060@freefall.freebsd.org>
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The following reply was made to PR misc/22936; it has been noted by GNATS.
From: Bruce Evans <bde@zeta.org.au>
To: dmaddox@sc.rr.com
Cc: FreeBSD-gnats-submit@FreeBSD.ORG
Subject: Re: misc/22936: <stdbool.h> broken, needs repair
Date: Sun, 19 Nov 2000 04:18:45 +1100 (EST)
On Sat, 18 Nov 2000 Donald.J.Maddox@cae88-102-101.sc.rr.com wrote:
> >Description:
> The header file <stdbool.h> contains a defective
> conditional that breaks several ports. Any code that includes
> <stdbool.h> will break if compiled by gcc... Example:
Much more is broken than that, at least according to a C99 draft (n869).
1) _Bool is a first class type (like int), so it can't be declared as
a typedef (unless compiler magic supports such a declaration).
2) `true' and `false' are supposed to be usable in cpp expressions, so
they can't be declared as enum values.
3) The definitions of `false' and `true' as themself don't work in K&R
mode. This is not a serious bug, since K&R code shouldn't include
<stdbool.h>.
4) Support for the Standard C (c99) _Bool is premature, since gcc doesn't
support _Bool as a first class type.
<stdbool.h> is essentially a compatibility hack for pre-c99 compilers.
The current version seems to be based on the gcc version. Both versions
will break when gcc actually supports _Bool.
Here is a version compatible with the C99 draft and K&R:
---
#define __bool_true_false_are_defined 1
#define false 0
#define true 1
#define bool _Bool
#if __STDC_VERSION__ < 199901L
typedef int _Bool;
#endif
---
Bruce
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