Date: Thu, 1 Jan 2004 11:30:22 -0800 (PST) From: Jason Evans <jasone@canonware.com> To: freebsd-standards@FreeBSD.org Subject: Re: standards/60772: _Bool and bool should be unsigned Message-ID: <200401011930.i01JUM9N076225@freefall.freebsd.org>
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The following reply was made to PR standards/60772; it has been noted by GNATS.
From: Jason Evans <jasone@canonware.com>
To: Bruce Evans <bde@zeta.org.au>
Cc: FreeBSD-gnats-submit@freebsd.org, freebsd-standards@freebsd.org
Subject: Re: standards/60772: _Bool and bool should be unsigned
Date: Thu, 1 Jan 2004 11:27:10 -0800
On Thu, Jan 01, 2004 at 03:52:08PM +1100, Bruce Evans wrote:
> The fake definition in FreeBSD-4.9 permits storing values between INT_MIN
> and INT_MAX, and changing it to unsigned so that it is limited to values
> between 0 and UINT_MAX isn't much of an improvment.
You're talking about the following problem, right?
{
int foo = 42;
bool bar;
/* This works okay. */
bar = foo ? true : false;
/* This breaks on 4.9. */
bar = foo;
}
This particular problem hasn't bitten me, but you're right that it's a
serious problem.
> I think the correct fix is to remove <stdbool.h> in RELENG_4, since it is
> impossible to implement it correctly.
This sounds reasonable to me, though doing so would potentially prevent
quite a number of ports from compiling. Still, it seems better to refuse
to compile, than to willingly generate bad binaries. This bug caused a
spectacular failure for some code I've been working on, but the resulting
bugs could easily have been much more subtle and gone unnoticed.
> Was there a defacto standard for it before C99? It doesn't seem to have
> been very common -- it isn't in glibc-2.2.5 (which is 2 years old, but
> not as old as <stdnool.h> in FreeBSD).
I don't don't think there was a defacto standard for this. The following
appears to be the original C99 addition document for stdbool.h:
http://std.dkuug.dk/JTC1/SC22/WG14/www/docs/n815.htm
Jason
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