Tracking Issue for `alloc_slice_into_array`.

Feature gate: #![feature(alloc_slice_into_array)]

Branched from: #133508

This is a tracking issue for adding conversion functions going from allocated slices to allocated arrays.

Public API

// alloc::boxed

impl<T> Box<[T]> {
    pub fn into_array<const N: usize>(self) -> Result<Box<[T; N]>, Self>;
}

// alloc::rc

impl<T> Rc<[T]> {
    pub fn into_array<const N: usize>(self) -> Result<Rc<[T; N]>, Self>;
}

// alloc::sync

impl<T> Arc<[T]> {
    pub fn into_array<const N: usize>(self) -> Result<Arc<[T; N]>, Self>;
}

// alloc::vec

impl<T> Vec<T> {
    pub fn into_array<const N: usize>(self) -> Result<Box<[T; N]>, Self>;
}

Steps / History

• API change proposal (ACP): #496
• Implementation:
  • Implementation for Box<[_]>, Rc<[_]>, and Arc<[_]>: #134379
  • Update feature gates and tracking issues in source: #147540
  • Support custom allocators: #154925
  • Reimplementation for using Result instead of Option: #156810
  • Implementation for Vec<_>: #156234
• Final comment period (FCP)
• Stabilisation

Unresolved Questions

• const-compatibility?
• Option or Result? : Result (assumed.)
• Implementations for Mutex and RwLock?
• Vec::into_boxed_array?
• String::into_boxed_bytes_array?

Start by reviewing the API change proposal #496 and the implementation PRs #134379, #154925, #156810, and #156234. Check the unresolved questions and the current feature-gate state; completion requires resolving the remaining design questions, holding the final comment period, and stabilizing the APIs.