Messing around with allocations

[abgros]

What will this do?

use std::alloc::{Layout, alloc};
use std::ptr;

fn main() {
	static NULL: *mut u8 = ptr::null_mut();

	unsafe {
		let new_alloc = alloc(Layout::from_size_align_unchecked(12, 4));
		if new_alloc == NULL {
			println!("allocation failed");
			return;
		}
		new_alloc.copy_from_nonoverlapping("Hello ".as_ptr(), 6);

		let mut s = String::from_raw_parts(new_alloc, 6, 12);
		s.push_str("world!");

		println!("{}", &s);
		let _v: Vec<u32> = Vec::from_raw_parts(s.leak().as_mut_ptr().cast(), 3, 3);
	}
}

Answer

error[E0277]: `*mut u8` cannot be shared between threads safely
 --> src\main.rs:5:15
  |
5 |     static NULL: *mut u8 = ptr::null_mut();
  |                  ^^^^^^^ `*mut u8` cannot be shared between threads safely
  |
  = help: the trait `Sync` is not implemented for `*mut u8`
  = note: shared static variables must have a type that implements `Sync`

For more information about this error, try `rustc --explain E0277`.
error: could not compile `rusttest` (bin "rusttest") due to 1 previous error

The rest of the code is correct.