Even more const

Author: usbalbin

library/core/src/lib.rs

@@ -92,6 +92,7 @@
 #![feature(const_ptr_offset)]
 #![feature(const_ptr_offset_from)]
 #![feature(const_raw_ptr_comparison)]
+#![feature(const_raw_ptr_deref)]
 #![feature(const_slice_from_raw_parts)]
 #![feature(const_slice_ptr_len)]
 #![feature(const_size_of_val)]

library/core/src/mem/maybe_uninit.rs

@@ -813,8 +813,9 @@ impl<T> MaybeUninit<T> {
     ///
     /// [`assume_init_ref`]: MaybeUninit::assume_init_ref
     #[unstable(feature = "maybe_uninit_slice", issue = "63569")]
+    #[rustc_const_unstable(feature = "const_maybe_assume_init", issue = "none")]
     #[inline(always)]
-    pub unsafe fn slice_assume_init_ref(slice: &[Self]) -> &[T] {
+    pub const unsafe fn slice_assume_init_ref(slice: &[Self]) -> &[T] {
         // SAFETY: casting slice to a `*const [T]` is safe since the caller guarantees that
         // `slice` is initialized, and`MaybeUninit` is guaranteed to have the same layout as `T`.
         // The pointer obtained is valid since it refers to memory owned by `slice` which is a
@@ -834,24 +835,27 @@ impl<T> MaybeUninit<T> {
     ///
     /// [`assume_init_mut`]: MaybeUninit::assume_init_mut
     #[unstable(feature = "maybe_uninit_slice", issue = "63569")]
+    #[rustc_const_unstable(feature = "const_maybe_assume_init", issue = "none")]
     #[inline(always)]
-    pub unsafe fn slice_assume_init_mut(slice: &mut [Self]) -> &mut [T] {
+    pub const unsafe fn slice_assume_init_mut(slice: &mut [Self]) -> &mut [T] {
         // SAFETY: similar to safety notes for `slice_get_ref`, but we have a
         // mutable reference which is also guaranteed to be valid for writes.
         unsafe { &mut *(slice as *mut [Self] as *mut [T]) }
     }
 
     /// Gets a pointer to the first element of the array.
     #[unstable(feature = "maybe_uninit_slice", issue = "63569")]
+    #[rustc_const_unstable(feature = "const_maybe_assume_init", issue = "none")]
     #[inline(always)]
-    pub fn slice_as_ptr(this: &[MaybeUninit<T>]) -> *const T {
+    pub const fn slice_as_ptr(this: &[MaybeUninit<T>]) -> *const T {
         this.as_ptr() as *const T
     }
 
     /// Gets a mutable pointer to the first element of the array.
     #[unstable(feature = "maybe_uninit_slice", issue = "63569")]
+    #[rustc_const_unstable(feature = "const_maybe_assume_init", issue = "none")]
     #[inline(always)]
-    pub fn slice_as_mut_ptr(this: &mut [MaybeUninit<T>]) -> *mut T {
+    pub const fn slice_as_mut_ptr(this: &mut [MaybeUninit<T>]) -> *mut T {
         this.as_mut_ptr() as *mut T
     }
 }