Auto merge of #90235 - matthiaskrgr:rollup-7pqtevk, r=matthiaskrgr

Rollup of 6 pull requests

Successful merges:

 - #89558 (Add rustc lint, warning when iterating over hashmaps)
 - #90100 (Skip documentation for tier 2 targets on dist-x86_64-apple-darwin)
 - #90155 (Fix alignment of method headings for scannability)
 - #90162 (Mark `{array, slice}::{from_ref, from_mut}` as const fn)
 - #90221 (Fix ICE when forgetting to `Box` a parameter to a `Self::func` call)
 - #90234 (Temporarily turn overflow checks off for rustc-rayon-core)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

3 files changed, 10 insertions, 4 deletions

diff --git a/library/core/src/array/mod.rs b/library/core/src/array/mod.rs
index 73340fda2cb..811850af367 100644
--- a/library/core/src/array/mod.rs
+++ b/library/core/src/array/mod.rs
@@ -85,14 +85,16 @@ where
 
 /// 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")]
-pub fn from_ref<T>(s: &T) -> &[T; 1] {
+#[rustc_const_unstable(feature = "const_array_from_ref", issue = "90206")]
+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]>() }
 }
 
 /// Converts a mutable reference to `T` into a mutable reference to an array of length 1 (without copying).
 #[stable(feature = "array_from_ref", since = "1.53.0")]
-pub fn from_mut<T>(s: &mut T) -> &mut [T; 1] {
+#[rustc_const_unstable(feature = "const_array_from_ref", issue = "90206")]
+pub const fn from_mut<T>(s: &mut T) -> &mut [T; 1] {
     // SAFETY: Converting `&mut T` to `&mut [T; 1]` is sound.
     unsafe { &mut *(s as *mut T).cast::<[T; 1]>() }
 }
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 58a170401e7..63c42068aad 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -136,6 +136,8 @@
 #![feature(ptr_metadata)]
 #![feature(slice_ptr_get)]
 #![feature(variant_count)]
+#![feature(const_array_from_ref)]
+#![feature(const_slice_from_ref)]
 //
 // Language features:
 #![feature(abi_unadjusted)]
diff --git a/library/core/src/slice/raw.rs b/library/core/src/slice/raw.rs
index eda50dc287f..ad38aaf9f83 100644
--- a/library/core/src/slice/raw.rs
+++ b/library/core/src/slice/raw.rs
@@ -138,12 +138,14 @@ pub unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a mut [T]
 
 /// Converts a reference to T into a slice of length 1 (without copying).
 #[stable(feature = "from_ref", since = "1.28.0")]
-pub fn from_ref<T>(s: &T) -> &[T] {
+#[rustc_const_unstable(feature = "const_slice_from_ref", issue = "90206")]
+pub const fn from_ref<T>(s: &T) -> &[T] {
     array::from_ref(s)
 }
 
 /// Converts a reference to T into a slice of length 1 (without copying).
 #[stable(feature = "from_ref", since = "1.28.0")]
-pub fn from_mut<T>(s: &mut T) -> &mut [T] {
+#[rustc_const_unstable(feature = "const_slice_from_ref", issue = "90206")]
+pub const fn from_mut<T>(s: &mut T) -> &mut [T] {
     array::from_mut(s)
 }