These methods stabilized in #125561 for rust 1.80 🎉

This issue is now tracking their const-stability.

Feature gate: #![feature(slice_flatten)]

This is a tracking issue for the methods flatten and flatten_mut on [[T; N]], and into_flattened on Vec<[T; N], A>.

Public API

// core::slice

impl<T, const N: usize> [[T; N]] {
    pub fn as_flattened(&self) -> &[T];
    pub fn as_flattened_mut(&mut self) -> &mut [T];
}

// alloc::vec

impl<T, A: Allocator, const N: usize> Vec<[T; N], A> {
    pub fn into_flattened(self) -> Vec<T, A>;
}

Steps / History

• Implementation: Add <[[T; N]]>::flatten{_mut} #95579
• Final comment period (FCP)
• Rename flatten(_mut) → as_flattened(_mut) #125171
• Stabilization PR Stabilize slice_flatten #125561
• Stabilize <[T]>::as_flattened const

Unresolved Questions

• Are these the best possible names?