[Bug c/39121] New: strange behavior of a chain of operations.

[nospam at pamies dot cat]

#include <stdio.h>

/*
  Why the first swap operation works as expected but
  it does not happen the same with the second one ?
  I guess that it can be due operations within temp values,
  but IMHO swap operation should work in both cases.

  Thanks !
 */

void swap(int *a, int *b) {
    *a ^= *b ^= *a ^= *b;
}

int main() {
    int a = 5;
    int b = 8;
    printf("%d, %d\n", a, b);
    a ^= b ^= a ^= b;
    printf("%d, %d\n", a, b);
    swap(&a, &b);
    printf("%d, %d\n", a, b);
}


-- 
           Summary: strange behavior of a chain of operations.
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: nospam at pamies dot cat


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39121