pub fn new_zeroed_in(alloc: A) -> Box<mem::MaybeUninit<T>, A> {
        let layout = Layout::new::<mem::MaybeUninit<T>>();
        // NOTE: Prefer match over unwrap_or_else since closure sometimes not inlineable.
        // That would make code size bigger.
        match Box::try_new_zeroed_in(alloc) {
            Ok(m) => m,
            Err(_) => handle_alloc_error(layout),
        }
    }
Constructs a new boxed slice with uninitialized contents.

# Examples

```
#![feature(new_uninit)]

let mut value
benchmarks/haystacks/code/rust-library.rs