// fn run_mut<F>(mut f: F)
// where
//     F: FnMut(u32) -> (),
// {
//     f(1);
// }

// fn foo(x: u32) -> u32 {
//     x + 1
// }

// fn main() {
//     let bar: fn(u32) -> u32 = foo; // function pointer
//     let y: u32 = bar(1);           // function call
//     assert!{y == 2};

//     let baz = |x| x + y;           // closure type
//     let z = baz(y);                // closure invocation
//     assert!(z == 4);

//     let mut b: u32 = 0;            // mutable variable

//     let bb = &mut b;               // mutable reference

//     let c1 = |x: u32| {            // closure parameter
//         move |y| {                 // x, bb into closure
//             *bb += x + y;
//         }
//     };

//     run_mut(c1(3));
//     assert!(b == 4);
// }

use core::cell::UnsafeCell;

struct Descriptor<T> {
    size : u8,
    rest: T
}

struct BUF(UnsafeCell<[u8; 32]>);
unsafe impl Sync for BUF {}

static BUFFER:BUF = BUF(unsafe { UnsafeCell::new([0; 32]) });

const A:Descriptor<Descriptor<&'static mut BUF>> = Descriptor {
    size : std::mem::size_of::<Descriptor<Descriptor<&'static mut BUF>>>() as u8,
    rest : Descriptor {
        size : std::mem::size_of::<Descriptor<&'static mut BUF>>() as u8,
        rest : &mut BUFFER
    },
};


// fn main() {
//   println!("{}", A.size);
// }