Date: Wed, 5 Mar 2003 16:49:50 -0500 (EST) From: Jonathan Lennox <lennox@cs.columbia.edu> To: FreeBSD-gnats-submit@FreeBSD.org Subject: bin/48958: The type 'bool' has different sizes for C and C++ Message-ID: <200303052149.h25LnoB4080988@conrail.cs.columbia.edu>
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>Number: 48958
>Category: bin
>Synopsis: The type 'bool' has different sizes for C and C++
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Wed Mar 05 13:50:10 PST 2003
>Closed-Date:
>Last-Modified:
>Originator: Jonathan Lennox
>Release: FreeBSD 4.7-RELEASE i386
>Organization:
Columbia University
>Environment:
System: FreeBSD conrail.cs.columbia.edu 4.7-RELEASE FreeBSD 4.7-RELEASE #2: Sun Nov 10 18:58:39 EST 2002 lennox@conrail.cs.columbia.edu:/usr/obj/usr/src/sys/CONRAIL i386
>Description:
The type 'bool' has different sizes and alignment in C and C++ code.
In C, the system header file stdbool.h typedef's '_Bool' as 'int', which has
size and alignment 4. The type bool is #defined to _Bool.
However, in C++, the built-in type 'bool' has size and alignment 1.
This means that structures which contain bool values can't be shared between
C and C++ code.
>How-To-Repeat:
Compile and execute the following program as C and C++ code, with
/usr/bin/cc and /usr/bin/c++.
#include <stdio.h>
#ifndef __cplusplus
#include <stdbool.h>
#endif
int main()
{
printf("%d\n", sizeof(bool));
return 0;
}
>Fix:
The correct fix would be to change /usr/include/stdbool.h to say 'typedef
char _Bool' rather than 'typedef int _Bool'. This changes the C ABI for
FreeBSD 4.x, but it makes it agree with the C++ ABI, and the C ABI for
FreeBSD 5.x.
Workarounds:
* Use FreeBSD 5.x (presumably; not tested).
* Don't use <stdbool.h>; instead, use a local typedef of bool as char.
>Release-Note:
>Audit-Trail:
>Unformatted:
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