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Rollup merge of rust-lang#130164 - RalfJung:const_ptr_as_ref, r=dtolnay
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move some const fn out of the const_ptr_as_ref feature

When a `const fn` is still `#[unstable]`, it should generally use the same feature to track its regular stability and const-stability. Then when that feature moves towards stabilization we can decide whether the const-ness can be stabilized as well, or whether it should be moved into a new feature.

Also, functions like `ptr::as_ref` (which returns an `Option<&mut T>`) require `is_null`, which is tricky and blocked on some design concerns (see rust-lang#74939). So move those to the is_null feature gate, as they should be stabilized together with `ptr.is_null()`.

Affects rust-lang#91822, rust-lang#122034, rust-lang#75402, rust-lang#74939
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workingjubilee authored Sep 10, 2024
2 parents 0ee8a56 + e10224a commit c1d1aef
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Showing 3 changed files with 16 additions and 16 deletions.
8 changes: 4 additions & 4 deletions library/core/src/ptr/const_ptr.rs
Original file line number Diff line number Diff line change
Expand Up @@ -270,7 +270,7 @@ impl<T: ?Sized> *const T {
/// }
/// ```
#[stable(feature = "ptr_as_ref", since = "1.9.0")]
#[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
#[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")]
#[inline]
pub const unsafe fn as_ref<'a>(self) -> Option<&'a T> {
// SAFETY: the caller must guarantee that `self` is valid
Expand Down Expand Up @@ -302,7 +302,7 @@ impl<T: ?Sized> *const T {
/// ```
// FIXME: mention it in the docs for `as_ref` and `as_uninit_ref` once stabilized.
#[unstable(feature = "ptr_as_ref_unchecked", issue = "122034")]
#[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
#[rustc_const_unstable(feature = "ptr_as_ref_unchecked", issue = "122034")]
#[inline]
#[must_use]
pub const unsafe fn as_ref_unchecked<'a>(self) -> &'a T {
Expand Down Expand Up @@ -336,7 +336,7 @@ impl<T: ?Sized> *const T {
/// ```
#[inline]
#[unstable(feature = "ptr_as_uninit", issue = "75402")]
#[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
#[rustc_const_unstable(feature = "ptr_as_uninit", issue = "75402")]
pub const unsafe fn as_uninit_ref<'a>(self) -> Option<&'a MaybeUninit<T>>
where
T: Sized,
Expand Down Expand Up @@ -1664,7 +1664,7 @@ impl<T> *const [T] {
/// [allocated object]: crate::ptr#allocated-object
#[inline]
#[unstable(feature = "ptr_as_uninit", issue = "75402")]
#[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
#[rustc_const_unstable(feature = "ptr_as_uninit", issue = "75402")]
pub const unsafe fn as_uninit_slice<'a>(self) -> Option<&'a [MaybeUninit<T>]> {
if self.is_null() {
None
Expand Down
16 changes: 8 additions & 8 deletions library/core/src/ptr/mut_ptr.rs
Original file line number Diff line number Diff line change
Expand Up @@ -261,7 +261,7 @@ impl<T: ?Sized> *mut T {
/// }
/// ```
#[stable(feature = "ptr_as_ref", since = "1.9.0")]
#[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
#[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")]
#[inline]
pub const unsafe fn as_ref<'a>(self) -> Option<&'a T> {
// SAFETY: the caller must guarantee that `self` is valid for a
Expand Down Expand Up @@ -295,7 +295,7 @@ impl<T: ?Sized> *mut T {
/// ```
// FIXME: mention it in the docs for `as_ref` and `as_uninit_ref` once stabilized.
#[unstable(feature = "ptr_as_ref_unchecked", issue = "122034")]
#[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
#[rustc_const_unstable(feature = "ptr_as_ref_unchecked", issue = "122034")]
#[inline]
#[must_use]
pub const unsafe fn as_ref_unchecked<'a>(self) -> &'a T {
Expand Down Expand Up @@ -334,7 +334,7 @@ impl<T: ?Sized> *mut T {
/// ```
#[inline]
#[unstable(feature = "ptr_as_uninit", issue = "75402")]
#[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
#[rustc_const_unstable(feature = "ptr_as_uninit", issue = "75402")]
pub const unsafe fn as_uninit_ref<'a>(self) -> Option<&'a MaybeUninit<T>>
where
T: Sized,
Expand Down Expand Up @@ -580,7 +580,7 @@ impl<T: ?Sized> *mut T {
/// println!("{s:?}"); // It'll print: "[4, 2, 3]".
/// ```
#[stable(feature = "ptr_as_ref", since = "1.9.0")]
#[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
#[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")]
#[inline]
pub const unsafe fn as_mut<'a>(self) -> Option<&'a mut T> {
// SAFETY: the caller must guarantee that `self` is be valid for
Expand Down Expand Up @@ -616,7 +616,7 @@ impl<T: ?Sized> *mut T {
/// ```
// FIXME: mention it in the docs for `as_mut` and `as_uninit_mut` once stabilized.
#[unstable(feature = "ptr_as_ref_unchecked", issue = "122034")]
#[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
#[rustc_const_unstable(feature = "ptr_as_ref_unchecked", issue = "122034")]
#[inline]
#[must_use]
pub const unsafe fn as_mut_unchecked<'a>(self) -> &'a mut T {
Expand All @@ -639,7 +639,7 @@ impl<T: ?Sized> *mut T {
/// the pointer is [convertible to a reference](crate::ptr#pointer-to-reference-conversion).
#[inline]
#[unstable(feature = "ptr_as_uninit", issue = "75402")]
#[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
#[rustc_const_unstable(feature = "ptr_as_uninit", issue = "75402")]
pub const unsafe fn as_uninit_mut<'a>(self) -> Option<&'a mut MaybeUninit<T>>
where
T: Sized,
Expand Down Expand Up @@ -2016,7 +2016,7 @@ impl<T> *mut [T] {
/// [allocated object]: crate::ptr#allocated-object
#[inline]
#[unstable(feature = "ptr_as_uninit", issue = "75402")]
#[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
#[rustc_const_unstable(feature = "ptr_as_uninit", issue = "75402")]
pub const unsafe fn as_uninit_slice<'a>(self) -> Option<&'a [MaybeUninit<T>]> {
if self.is_null() {
None
Expand Down Expand Up @@ -2068,7 +2068,7 @@ impl<T> *mut [T] {
/// [allocated object]: crate::ptr#allocated-object
#[inline]
#[unstable(feature = "ptr_as_uninit", issue = "75402")]
#[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
#[rustc_const_unstable(feature = "ptr_as_uninit", issue = "75402")]
pub const unsafe fn as_uninit_slice_mut<'a>(self) -> Option<&'a mut [MaybeUninit<T>]> {
if self.is_null() {
None
Expand Down
8 changes: 4 additions & 4 deletions library/core/src/ptr/non_null.rs
Original file line number Diff line number Diff line change
Expand Up @@ -133,7 +133,7 @@ impl<T: Sized> NonNull<T> {
#[inline]
#[must_use]
#[unstable(feature = "ptr_as_uninit", issue = "75402")]
#[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
#[rustc_const_unstable(feature = "ptr_as_uninit", issue = "75402")]
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.
Expand All @@ -157,7 +157,7 @@ impl<T: Sized> NonNull<T> {
#[inline]
#[must_use]
#[unstable(feature = "ptr_as_uninit", issue = "75402")]
#[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
#[rustc_const_unstable(feature = "ptr_as_uninit", issue = "75402")]
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.
Expand Down Expand Up @@ -1563,7 +1563,7 @@ impl<T> NonNull<[T]> {
#[inline]
#[must_use]
#[unstable(feature = "ptr_as_uninit", issue = "75402")]
#[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
#[rustc_const_unstable(feature = "ptr_as_uninit", issue = "75402")]
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()) }
Expand Down Expand Up @@ -1628,7 +1628,7 @@ impl<T> NonNull<[T]> {
#[inline]
#[must_use]
#[unstable(feature = "ptr_as_uninit", issue = "75402")]
#[rustc_const_unstable(feature = "const_ptr_as_ref", issue = "91822")]
#[rustc_const_unstable(feature = "ptr_as_uninit", issue = "75402")]
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()) }
Expand Down

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