Bug#903771: c99: buggy POSIX abs(INT_MIN)

[Vincent Lefevre <vincent@vinc17.net>]

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