use std::ptr;

struct A {
    a: i32,
    b: *const i32
}

impl A {
    pub fn new(a: i32) -> Self {
        let mut result = Self {
            a,
            b: ptr::null()
        };
        let ptr = &result.a as *const _;
        result.b = ptr;

        unsafe {
            println!("{}", *result.b);
        }

        result
    }
}

fn main() {
    let a = A::new(10);
    unsafe {
        println!("{}", *a.b);
    }
}