Repository: rust
Issue: Tracking Issue for MaybeUninit methods for arrays
Labels: T-libs-api,C-tracking-issue,finished-final-comment-period,disposition-close

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This is a meta-tracking issue for multiple APIs that are linked across multiple issues. Right now it only includes two methods, but since there seems to be a desire to add more, this issue can be used as a placeholder for those discussions until those methods are added.

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### Public API

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```rust
impl<T> MaybeUninit<T> {
    pub const fn uninit_array<const N: usize>() -> [Self; N];
    pub const fn array_assume_init<const N: usize>(array: [Self; N]) -> [T; N];
}

impl<T, const N: usize> MaybeUninit<[T; N]> {
    pub const fn transpose(self) -> [MaybeUninit<T>; N];
}

impl<T, const N: usize> [MaybeUninit<T>; N] {
    pub const fn transpose(self) -> MaybeUninit<[T; N]>;
}
```

### Steps / History

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- [x] #65580 
- [x] #80600
- [x] Make const: #96099
- [x] #102023
- [ ] Final comment period (FCP)
- [ ] Stabilization PR

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### Relevant Links

* Old tracking issue for array_assume_init: #80908

### Unresolved Questions

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- Should `MaybeUninit::uninit_array::<LEN>()` be stabilised if it can be replaced by `[const { MaybeUninit::uninit() }; LEN]` ?
- What other APIs should be added for arrays?
- Is `array_assume_init` the right pattern, or should we convert from `[MaybeUninit<T>, N]` back to `MaybeUninit<[T; N]>` first?