Auto merge of rust-lang#96100 - Raekye:master, r=dtolnay

Change `NonNull::as_uninit_*` to take self by value (as opposed to reference), matching primitive pointers.

Copied from my comment on [rust-lang#75402](rust-lang#75402 (comment)):

> I noticed that `as_uninit_*` on pointers take `self` by value (and pointers are `Copy`), e.g. see [`as_uninit_mut`](https://doc.rust-lang.org/core/primitive.pointer.html#method.as_uninit_mut).
>
> However, on `NonNull`, these functions take `self` by reference, e.g. see the function with the same name by for `NonNull`: [`as_uninit_mut`](https://doc.rust-lang.org/std/ptr/struct.NonNull.html#method.as_uninit_mut) takes `self` by mutable reference. Even more inconsistent, [`as_uninit_slice_mut`](https://doc.rust-lang.org/std/ptr/struct.NonNull.html#method.as_uninit_slice_mut) returns a mutable reference, but takes `self` by immutable reference.
>
> I think these methods should take `self` by value for consistency. The returned lifetime is unbounded anyways and not tied to the pointer/NonNull value anyways

I realized the change is trivial (if desired) so here I am creating my first PR. I think it's not a breaking change since (it's on nightly and) `NonNull` is `Copy`; all previous usages of these methods taking `self` by reference should continue to compile. However, it might cause warnings to appear on usages of `NonNull::as_uninit_mut`, which used to require the the `NonNull` variable be declared `mut`, but now it's not necessary.

Author: bors

library/core/src/ptr/non_null.rs

@@ -125,7 +125,7 @@ impl<T: Sized> NonNull<T> {
     #[must_use]
     #[unstable(feature = "ptr_as_uninit", issue = "75402")]
     #[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
-    pub const unsafe fn as_uninit_ref<'a>(&self) -> &'a MaybeUninit<T> {
+    pub const unsafe fn as_uninit_ref<'a>(self) -> &'a MaybeUninit<T> {
         // SAFETY: the caller must guarantee that `self` meets all the
         // requirements for a reference.
         unsafe { &*self.cast().as_ptr() }
@@ -159,7 +159,7 @@ impl<T: Sized> NonNull<T> {
     #[must_use]
     #[unstable(feature = "ptr_as_uninit", issue = "75402")]
     #[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
-    pub const unsafe fn as_uninit_mut<'a>(&mut self) -> &'a mut MaybeUninit<T> {
+    pub const unsafe fn as_uninit_mut<'a>(self) -> &'a mut MaybeUninit<T> {
         // SAFETY: the caller must guarantee that `self` meets all the
         // requirements for a reference.
         unsafe { &mut *self.cast().as_ptr() }
@@ -593,7 +593,7 @@ impl<T> NonNull<[T]> {
     #[must_use]
     #[unstable(feature = "ptr_as_uninit", issue = "75402")]
     #[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
-    pub const unsafe fn as_uninit_slice<'a>(&self) -> &'a [MaybeUninit<T>] {
+    pub const unsafe fn as_uninit_slice<'a>(self) -> &'a [MaybeUninit<T>] {
         // SAFETY: the caller must uphold the safety contract for `as_uninit_slice`.
         unsafe { slice::from_raw_parts(self.cast().as_ptr(), self.len()) }
     }
@@ -656,7 +656,7 @@ impl<T> NonNull<[T]> {
     #[must_use]
     #[unstable(feature = "ptr_as_uninit", issue = "75402")]
     #[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
-    pub const unsafe fn as_uninit_slice_mut<'a>(&self) -> &'a mut [MaybeUninit<T>] {
+    pub const unsafe fn as_uninit_slice_mut<'a>(self) -> &'a mut [MaybeUninit<T>] {
         // SAFETY: the caller must uphold the safety contract for `as_uninit_slice_mut`.
         unsafe { slice::from_raw_parts_mut(self.cast().as_ptr(), self.len()) }
     }