use std::cell::UnsafeCell;

fn main() { unsafe {
    let c = &UnsafeCell::new(UnsafeCell::new(0));
    let inner_uniq = &mut *c.get();
    // stack: [c: SharedReadWrite, inner_uniq: Unique]

    let inner_shr = &*inner_uniq; // adds a SharedReadWrite
    // stack: [c: SharedReadWrite, inner_uniq: Unique, inner_shr: SharedReadWrite]

    *c.get() = UnsafeCell::new(1); // invalidates inner_shr
    // stack: [c: SharedReadWrite]

    let _val = *inner_shr.get(); //~ ERROR borrow stack
} }