add Cell::as_array_of_cells, similar to Cell::as_slice_of_cells

[oconnor663]

I'd like to propose adding Cell::as_array_of_cells, as a natural analog to Cell::as_slice_of_cells. I don't have a specific use case in mind, other than that supporting slices but not arrays feels like a gap. Do other folks agree with that intuition? Would this addition be substantial enough to need an RFC?

---

Previously, converting &mut [T; N] to &[Cell<T>; N] looks like this:

let array = &mut [1, 2, 3];
let cells: &[Cell<i32>; 3] = Cell::from_mut(&mut array[..])
    .as_slice_of_cells()
    .try_into()
    .unwrap();

With this new helper method, it looks like this:

let array = &mut [1, 2, 3];
let cells = Cell::from_mut(array).as_array_of_cells();

[rust-highfive]

r? @scottmcm

(rust-highfive has picked a reviewer for you, use r? to override)

[oconnor663]

I've put a standalone version of this function in this repo: https://github.com/oconnor663/cell_utils

[oconnor663]

@scottmcm should I add someone else to review?

[scottmcm]

Sorry for being slow. This seems perfectly reasonable to me, given that it's already possible (much less nicely) by going through slices. Can you open a Library Tracking Issue for it, and add that to the unstable attribute?

[oconnor663]

No worries. Done!

[scottmcm]

@bors r+

[bors]

📌 Commit 9c44d80 has been approved by scottmcm