Implement ptr_cast_array

Author: scottmcm

library/core/src/ptr/const_ptr.rs

@@ -1547,6 +1547,15 @@ impl<T> *const [T] {
     }
 }
 
+impl<T> *const T {
+    /// Casts from a pointer-to-`T` to a pointer-to-`[T; N]`.
+    #[inline]
+    #[unstable(feature = "ptr_cast_array", issue = "144514")]
+    pub const fn cast_array<const N: usize>(self) -> *const [T; N] {
+        self.cast()
+    }
+}
+
 impl<T, const N: usize> *const [T; N] {
     /// Returns a raw pointer to the array's buffer.
     ///

library/core/src/ptr/mut_ptr.rs

@@ -1965,6 +1965,15 @@ impl<T> *mut [T] {
     }
 }
 
+impl<T> *mut T {
+    /// Casts from a pointer-to-`T` to a pointer-to-`[T; N]`.
+    #[inline]
+    #[unstable(feature = "ptr_cast_array", issue = "144514")]
+    pub const fn cast_array<const N: usize>(self) -> *mut [T; N] {
+        self.cast()
+    }
+}
+
 impl<T, const N: usize> *mut [T; N] {
     /// Returns a raw pointer to the array's buffer.
     ///

library/core/src/ptr/non_null.rs

@@ -193,6 +193,13 @@ impl<T: Sized> NonNull<T> {
         // requirements for a reference.
         unsafe { &mut *self.cast().as_ptr() }
     }
+
+    /// Casts from a pointer-to-`T` to a pointer-to-`[T; N]`.
+    #[inline]
+    #[unstable(feature = "ptr_cast_array", issue = "144514")]
+    pub const fn cast_array<const N: usize>(self) -> NonNull<[T; N]> {
+        self.cast()
+    }
 }
 
 impl<T: PointeeSized> NonNull<T> {