Your message dated Thu, 19 Jul 2018 15:00:36 +0200
with message-id <[email protected]>
and subject line Re: c99: buggy POSIX abs(INT_MIN)
has caused the Debian Bug report #903771,
regarding c99: buggy POSIX abs(INT_MIN)
to be marked as done.
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Bug report if necessary, and/or fix the problem forthwith.
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--
903771: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=903771
Debian Bug Tracking System
Contact [email protected] with problems
--- Begin Message ---
Package: gcc
Version: 4:7.3.0-3
Severity: normal
In the new POSIX abs() specification:
If the result cannot be represented, the result shall be {INT_MIN}.
instead of being undefined behavior. See:
http://austingroupbugs.net/view.php?id=1108#c4041
Thus the following program
----------------------------------------
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
int main (void)
{
volatile int i = INT_MIN;
int j;
j = abs (i);
printf ("%d %d\n", j, j >= 0);
return 0;
}
----------------------------------------
should output -2147483648 0 when compiled with the c99 utility. But:
zira:~> c99 -O2 -o tst tst.c
zira:~> ./tst
-2147483648 1
-- System Information:
Debian Release: buster/sid
APT prefers unstable-debug
APT policy: (500, 'unstable-debug'), (500, 'stable-updates'), (500,
'unstable'), (500, 'testing'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Kernel: Linux 4.16.0-2-amd64 (SMP w/8 CPU cores)
Locale: LANG=POSIX, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=POSIX
(charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled
Versions of packages gcc depends on:
ii cpp 4:7.3.0-3
ii gcc-7 7.3.0-25
Versions of packages gcc recommends:
ii libc6-dev [libc-dev] 2.27-4
Versions of packages gcc suggests:
ii autoconf 2.69-11+local1
ii automake 1:1.15.1-3.1
ii bison 2:3.0.4.dfsg-1+b1
pn flex <none>
ii gcc-doc 5:7.2.0-2
ii gcc-multilib 4:7.3.0-3
ii gdb 7.12-6+b2
ii libtool 2.4.6-2.1+local1
ii make 4.2.1-1.1
ii manpages-dev 4.16-1
-- no debconf information
--- End Message ---
--- Begin Message ---
On 2018-07-14 17:19:09 +0200, Vincent Lefevre wrote:
> In the new POSIX abs() specification:
>
> If the result cannot be represented, the result shall be {INT_MIN}.
>
> instead of being undefined behavior. See:
>
> http://austingroupbugs.net/view.php?id=1108#c4041
Closing the bug for now since this is for the next issue only,
and the utility name for compiling is not known yet.
There's also some hope that this change in POSIX will be reverted.
--
Vincent Lefèvre <[email protected]> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)
--- End Message ---
