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.

Public API

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

• Add MaybeUninit methods uninit_array, slice_get_ref, slice_get_mut #65580
• Add MaybeUninit method array_assume_init #80600
• Make const: MaybeUninit array cleanup #96099
• Add MaybeUninit array transpose impls #102023
• Final comment period (FCP)
• Stabilization PR

Relevant Links

• Old tracking issue for array_assume_init: Tracking Issue for maybe_uninit_array_assume_init #80908

Unresolved Questions

• 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?