Rollup merge of #97366 - WaffleLapkin:stabilize_array_slice_from_ref, r=dtolnay

Stabilize `{slice,array}::from_ref`

This PR stabilizes the following APIs as `const` functions in Rust `1.63`:
```rust
// core::array
pub const fn from_ref<T>(s: &T) -> &[T; 1];

// core::slice
pub const fn from_ref<T>(s: &T) -> &[T];
```

Note that the `mut` versions are not stabilized as unique references (`&mut _`) are [unstable in const context].

FCP: https://github.com/rust-lang/rust/issues/90206#issuecomment-1134586665

r? rust-lang/libs-api `@rustbot` label +T-libs-api -T-libs

[unstable in const context]: https://github.com/rust-lang/rust/issues/57349
This commit is contained in:
Dylan DPC 2022-06-03 11:18:23 +02:00 committed by GitHub
commit 025cf96615
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2 changed files with 2 additions and 2 deletions

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@ -92,7 +92,7 @@
/// Converts a reference to `T` into a reference to an array of length 1 (without copying).
#[stable(feature = "array_from_ref", since = "1.53.0")]
#[rustc_const_unstable(feature = "const_array_from_ref", issue = "90206")]
#[rustc_const_stable(feature = "const_array_from_ref_shared", since = "1.63.0")]
pub const fn from_ref<T>(s: &T) -> &[T; 1] {
// SAFETY: Converting `&T` to `&[T; 1]` is sound.
unsafe { &*(s as *const T).cast::<[T; 1]>() }

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@ -144,7 +144,7 @@
/// Converts a reference to T into a slice of length 1 (without copying).
#[stable(feature = "from_ref", since = "1.28.0")]
#[rustc_const_unstable(feature = "const_slice_from_ref", issue = "90206")]
#[rustc_const_stable(feature = "const_slice_from_ref_shared", since = "1.63.0")]
#[must_use]
pub const fn from_ref<T>(s: &T) -> &[T] {
array::from_ref(s)