standards/60772: _Bool and bool should be unsigned

Jason Evans jasone at
Thu Jan 1 11:30:31 PST 2004

The following reply was made to PR standards/60772; it has been noted by GNATS.

From: Jason Evans <jasone at>
To: Bruce Evans <bde at>
Cc: FreeBSD-gnats-submit at, freebsd-standards at
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:

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