#include <iostream>

using namespace std;

struct A
{
    int x;
};

void foo(const A &a)
{
    int * p = (int *)&a;
    *p = 8;
}

int main(int argc, char** args)
{
    A a;
    a.x = 3;
    foo(a);
    cout << a.x << endl;
}

8