fn from(s: [T; N]) -> Vec<T> {
        crate::slice::into_vec(box s)
    }
Gets the entire contents of the `Vec<T>` as an array,
if its size exactly matches that of the requested array.

# Examples

```
use std::convert::TryInto;
assert_eq!(vec![1, 2, 3].try_into(), Ok([1, 2, 3]));
assert_eq!(<Vec<i32>>::new().try_into(), Ok([]));
```

If the length doesn't match, the input comes back in `Err`
benchmarks/haystacks/code/rust-library.rs