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#![feature(new_zeroed_alloc)]

use std::mem::MaybeUninit;
use std::ptr;

#[unsafe(no_mangle)]
pub fn directly_initialize_on_heap() {
    let mut val: Box<MaybeUninit<Complex>> = Box::<Complex>::new_uninit();
    let raw: *mut Complex = val.as_mut_ptr();
    let _final: Box<Complex> = unsafe {
        // 1. Get a raw pointer to the specific field *within* the heap allocation.
        // `addr_of_mut!` is crucial as it doesn't create a temporary reference.
        let big_member_ptr: *mut [i32; 160] = ptr::addr_of_mut!((*raw).big_member);

// 2. Initialize that field directly. Here, we can use `write_bytes`
        // on the field itself.
        ptr::write_bytes(big_member_ptr, 0u8, 1);
        val.assume_init()
    };
    // you are now be able to use _final here.
}

#[unsafe(no_mangle)]
pub fn initialize_on_heap_simplify() {
    let zero: Box<MaybeUninit<Complex>> = Box::<Complex>::new_zeroed();
    let _: Box<Complex> = unsafe { zero.assume_init() };
}

#[repr(C)]
pub struct Complex {
    pub big_member: [i32; 160],
}