https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96549
Bug ID: 96549
Summary: Wrong evaluation of a comparison between long & short
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: zhige.yu18 at imperial dot ac.uk
Target Milestone: ---
The following code snippet:
#include <stdio.h>
long c = -1L;
long b = 0L;
int main(void) {
if (3L > (short) ((c ^= (b = 1L)) * 3L))
printf("hello ");
printf("world!\n");
}
> $ /usr/gcc-trunk/bin/gcc -O0 bug.c -o a.out; ./a.out
> world!
> $ clang-10 -O0 bug.c -o a.out; ./a.out
> hello world!
When compiled with -O0/1/2/3, GCC omits the then-branch of the if-statement,
and prints "world!" only. This bug can be found in GCC-10.2.0 and GCC-11.0.0
20200804 (experimental). GCC-9.3.0 and earlier versions of GCC do not have this
bug.
