Merging upstream version 1.76.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

6 files changed, 1218 insertions, 108 deletions

diff --git a/library/core/src/ptr/alignment.rs b/library/core/src/ptr/alignment.rs
index bbf7199ff..ce176e6fc 100644
--- a/library/core/src/ptr/alignment.rs
+++ b/library/core/src/ptr/alignment.rs
@@ -1,5 +1,4 @@
 use crate::convert::{TryFrom, TryInto};
-use crate::intrinsics::assert_unsafe_precondition;
 use crate::num::NonZeroUsize;
 use crate::{cmp, fmt, hash, mem, num};
 
@@ -42,6 +41,7 @@ impl Alignment {
     /// This provides the same numerical value as [`mem::align_of`],
     /// but in an `Alignment` instead of a `usize`.
     #[unstable(feature = "ptr_alignment_type", issue = "102070")]
+    #[rustc_const_unstable(feature = "ptr_alignment_type", issue = "102070")]
     #[inline]
     pub const fn of<T>() -> Self {
         // SAFETY: rustc ensures that type alignment is always a power of two.
@@ -53,6 +53,7 @@ impl Alignment {
     ///
     /// Note that `0` is not a power of two, nor a valid alignment.
     #[unstable(feature = "ptr_alignment_type", issue = "102070")]
+    #[rustc_const_unstable(feature = "ptr_alignment_type", issue = "102070")]
     #[inline]
     pub const fn new(align: usize) -> Option<Self> {
         if align.is_power_of_two() {
@@ -75,13 +76,10 @@ impl Alignment {
     #[rustc_const_unstable(feature = "ptr_alignment_type", issue = "102070")]
     #[inline]
     pub const unsafe fn new_unchecked(align: usize) -> Self {
-        // SAFETY: Precondition passed to the caller.
-        unsafe {
-            assert_unsafe_precondition!(
-               "Alignment::new_unchecked requires a power of two",
-                (align: usize) => align.is_power_of_two()
-            )
-        };
+        crate::panic::debug_assert_nounwind!(
+            align.is_power_of_two(),
+            "Alignment::new_unchecked requires a power of two"
+        );
 
         // SAFETY: By precondition, this must be a power of two, and
         // our variants encompass all possible powers of two.
@@ -98,6 +96,7 @@ impl Alignment {
 
     /// Returns the alignment as a [`NonZeroUsize`]
     #[unstable(feature = "ptr_alignment_type", issue = "102070")]
+    #[rustc_const_unstable(feature = "ptr_alignment_type", issue = "102070")]
     #[inline]
     pub const fn as_nonzero(self) -> NonZeroUsize {
         // SAFETY: All the discriminants are non-zero.
@@ -118,10 +117,42 @@ impl Alignment {
     /// assert_eq!(Alignment::new(1024).unwrap().log2(), 10);
     /// ```
     #[unstable(feature = "ptr_alignment_type", issue = "102070")]
+    #[rustc_const_unstable(feature = "ptr_alignment_type", issue = "102070")]
     #[inline]
-    pub fn log2(self) -> u32 {
+    pub const fn log2(self) -> u32 {
         self.as_nonzero().trailing_zeros()
     }
+
+    /// Returns a bit mask that can be used to match this alignment.
+    ///
+    /// This is equivalent to `!(self.as_usize() - 1)`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(ptr_alignment_type)]
+    /// #![feature(ptr_mask)]
+    /// use std::ptr::{Alignment, NonNull};
+    ///
+    /// #[repr(align(1))] struct Align1(u8);
+    /// #[repr(align(2))] struct Align2(u16);
+    /// #[repr(align(4))] struct Align4(u32);
+    /// let one = <NonNull<Align1>>::dangling().as_ptr();
+    /// let two = <NonNull<Align2>>::dangling().as_ptr();
+    /// let four = <NonNull<Align4>>::dangling().as_ptr();
+    ///
+    /// assert_eq!(four.mask(Alignment::of::<Align1>().mask()), four);
+    /// assert_eq!(four.mask(Alignment::of::<Align2>().mask()), four);
+    /// assert_eq!(four.mask(Alignment::of::<Align4>().mask()), four);
+    /// assert_ne!(one.mask(Alignment::of::<Align4>().mask()), one);
+    /// ```
+    #[unstable(feature = "ptr_alignment_type", issue = "102070")]
+    #[rustc_const_unstable(feature = "ptr_alignment_type", issue = "102070")]
+    #[inline]
+    pub const fn mask(self) -> usize {
+        // SAFETY: The alignment is always nonzero, and therefore decrementing won't overflow.
+        !(unsafe { self.as_usize().unchecked_sub(1) })
+    }
 }
 
 #[unstable(feature = "ptr_alignment_type", issue = "102070")]
@@ -193,6 +224,14 @@ impl hash::Hash for Alignment {
     }
 }
 
+/// Returns [`Alignment::MIN`], which is valid for any type.
+#[unstable(feature = "ptr_alignment_type", issue = "102070")]
+impl Default for Alignment {
+    fn default() -> Alignment {
+        Alignment::MIN
+    }
+}
+
 #[cfg(target_pointer_width = "16")]
 type AlignmentEnum = AlignmentEnum16;
 #[cfg(target_pointer_width = "32")]
diff --git a/library/core/src/ptr/const_ptr.rs b/library/core/src/ptr/const_ptr.rs
index 36685f756..a444c30c7 100644
--- a/library/core/src/ptr/const_ptr.rs
+++ b/library/core/src/ptr/const_ptr.rs
@@ -1,7 +1,7 @@
 use super::*;
-use crate::cmp::Ordering::{self, Equal, Greater, Less};
-use crate::intrinsics::{self, const_eval_select};
-use crate::mem::{self, SizedTypeProperties};
+use crate::cmp::Ordering::{Equal, Greater, Less};
+use crate::intrinsics::const_eval_select;
+use crate::mem::SizedTypeProperties;
 use crate::slice::{self, SliceIndex};
 
 impl<T: ?Sized> *const T {
@@ -186,10 +186,10 @@ impl<T: ?Sized> *const T {
     /// [`with_addr`][pointer::with_addr] or [`map_addr`][pointer::map_addr].
     ///
     /// If using those APIs is not possible because there is no way to preserve a pointer with the
-    /// required provenance, use [`expose_addr`][pointer::expose_addr] and
-    /// [`from_exposed_addr`][from_exposed_addr] instead. However, note that this makes
-    /// your code less portable and less amenable to tools that check for compliance with the Rust
-    /// memory model.
+    /// required provenance, then Strict Provenance might not be for you. Use pointer-integer casts
+    /// or [`expose_addr`][pointer::expose_addr] and [`from_exposed_addr`][from_exposed_addr]
+    /// instead. However, note that this makes your code less portable and less amenable to tools
+    /// that check for compliance with the Rust memory model.
     ///
     /// On most platforms this will produce a value with the same bytes as the original
     /// pointer, because all the bytes are dedicated to describing the address.
@@ -219,7 +219,8 @@ impl<T: ?Sized> *const T {
     /// later call [`from_exposed_addr`][] to reconstitute the original pointer including its
     /// provenance. (Reconstructing address space information, if required, is your responsibility.)
     ///
-    /// Using this method means that code is *not* following Strict Provenance rules. Supporting
+    /// Using this method means that code is *not* following [Strict
+    /// Provenance][../index.html#strict-provenance] rules. Supporting
     /// [`from_exposed_addr`][] complicates specification and reasoning and may not be supported by
     /// tools that help you to stay conformant with the Rust memory model, so it is recommended to
     /// use [`addr`][pointer::addr] wherever possible.
@@ -230,13 +231,13 @@ impl<T: ?Sized> *const T {
     /// side-effect which is required for [`from_exposed_addr`][] to work is typically not
     /// available.
     ///
-    /// This API and its claimed semantics are part of the Strict Provenance experiment, see the
-    /// [module documentation][crate::ptr] for details.
+    /// It is unclear whether this method can be given a satisfying unambiguous specification. This
+    /// API and its claimed semantics are part of [Exposed Provenance][../index.html#exposed-provenance].
     ///
     /// [`from_exposed_addr`]: from_exposed_addr
     #[must_use]
     #[inline(always)]
-    #[unstable(feature = "strict_provenance", issue = "95228")]
+    #[unstable(feature = "exposed_provenance", issue = "95228")]
     pub fn expose_addr(self) -> usize {
         // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
         self.cast::<()>() as usize
@@ -1367,10 +1368,16 @@ impl<T: ?Sized> *const T {
             panic!("align_offset: align is not a power-of-two");
         }
 
-        {
-            // SAFETY: `align` has been checked to be a power of 2 above
-            unsafe { align_offset(self, align) }
+        // SAFETY: `align` has been checked to be a power of 2 above
+        let ret = unsafe { align_offset(self, align) };
+
+        // Inform Miri that we want to consider the resulting pointer to be suitably aligned.
+        #[cfg(miri)]
+        if ret != usize::MAX {
+            intrinsics::miri_promise_symbolic_alignment(self.wrapping_add(ret).cast(), align);
         }
+
+        ret
     }
 
     /// Returns whether the pointer is properly aligned for `T`.
@@ -1644,6 +1651,24 @@ impl<T> *const [T] {
         metadata(self)
     }
 
+    /// Returns `true` if the raw slice has a length of 0.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(slice_ptr_len)]
+    /// use std::ptr;
+    ///
+    /// let slice: *const [i8] = ptr::slice_from_raw_parts(ptr::null(), 3);
+    /// assert!(!slice.is_empty());
+    /// ```
+    #[inline(always)]
+    #[unstable(feature = "slice_ptr_len", issue = "71146")]
+    #[rustc_const_unstable(feature = "const_slice_ptr_len", issue = "71146")]
+    pub const fn is_empty(self) -> bool {
+        self.len() == 0
+    }
+
     /// Returns a raw pointer to the slice's buffer.
     ///
     /// This is equivalent to casting `self` to `*const T`, but more type-safe.
@@ -1747,6 +1772,7 @@ impl<T> *const [T] {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> PartialEq for *const T {
     #[inline]
+    #[cfg_attr(not(bootstrap), allow(ambiguous_wide_pointer_comparisons))]
     fn eq(&self, other: &*const T) -> bool {
         *self == *other
     }
@@ -1759,6 +1785,7 @@ impl<T: ?Sized> Eq for *const T {}
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> Ord for *const T {
     #[inline]
+    #[cfg_attr(not(bootstrap), allow(ambiguous_wide_pointer_comparisons))]
     fn cmp(&self, other: &*const T) -> Ordering {
         if self < other {
             Less
@@ -1778,21 +1805,25 @@ impl<T: ?Sized> PartialOrd for *const T {
     }
 
     #[inline]
+    #[cfg_attr(not(bootstrap), allow(ambiguous_wide_pointer_comparisons))]
     fn lt(&self, other: &*const T) -> bool {
         *self < *other
     }
 
     #[inline]
+    #[cfg_attr(not(bootstrap), allow(ambiguous_wide_pointer_comparisons))]
     fn le(&self, other: &*const T) -> bool {
         *self <= *other
     }
 
     #[inline]
+    #[cfg_attr(not(bootstrap), allow(ambiguous_wide_pointer_comparisons))]
     fn gt(&self, other: &*const T) -> bool {
         *self > *other
     }
 
     #[inline]
+    #[cfg_attr(not(bootstrap), allow(ambiguous_wide_pointer_comparisons))]
     fn ge(&self, other: &*const T) -> bool {
         *self >= *other
     }
diff --git a/library/core/src/ptr/mod.rs b/library/core/src/ptr/mod.rs
index d71079dd0..390e07371 100644
--- a/library/core/src/ptr/mod.rs
+++ b/library/core/src/ptr/mod.rs
@@ -312,22 +312,30 @@
 //!   For instance, ARM explicitly supports high-bit tagging, and so CHERI on ARM inherits
 //!   that and should support it.
 //!
-//! ## Pointer-usize-pointer roundtrips and 'exposed' provenance
+//! ## Exposed Provenance
 //!
-//! **This section is *non-normative* and is part of the [Strict Provenance] experiment.**
+//! **This section is *non-normative* and is an extension to the [Strict Provenance] experiment.**
 //!
 //! As discussed above, pointer-usize-pointer roundtrips are not possible under [Strict Provenance].
-//! However, there exists legacy Rust code that is full of such roundtrips, and legacy platform APIs
-//! regularly assume that `usize` can capture all the information that makes up a pointer. There
-//! also might be code that cannot be ported to Strict Provenance (which is something we would [like
-//! to hear about][Strict Provenance]).
-//!
-//! For situations like this, there is a fallback plan, a way to 'opt out' of Strict Provenance.
-//! However, note that this makes your code a lot harder to specify, and the code will not work
-//! (well) with tools like [Miri] and [CHERI].
-//!
-//! This fallback plan is provided by the [`expose_addr`] and [`from_exposed_addr`] methods (which
-//! are equivalent to `as` casts between pointers and integers). [`expose_addr`] is a lot like
+//! This is by design: the goal of Strict Provenance is to provide a clear specification that we are
+//! confident can be formalized unambiguously and can be subject to  precise formal reasoning.
+//!
+//! However, there exist situations where pointer-usize-pointer roundtrips cannot be avoided, or
+//! where avoiding them would require major refactoring. Legacy platform APIs also regularly assume
+//! that `usize` can capture all the information that makes up a pointer. The goal of Strict
+//! Provenance is not to rule out such code; the goal is to put all the *other* pointer-manipulating
+//! code onto a more solid foundation. Strict Provenance is about improving the situation where
+//! possible (all the code that can be written with Strict Provenance) without making things worse
+//! for situations where Strict Provenance is insufficient.
+//!
+//! For these situations, there is a highly experimental extension to Strict Provenance called
+//! *Exposed Provenance*. This extension permits pointer-usize-pointer roundtrips. However, its
+//! semantics are on much less solid footing than Strict Provenance, and at this point it is not yet
+//! clear where a satisfying unambiguous semantics can be defined for Exposed Provenance.
+//! Furthermore, Exposed Provenance will not work (well) with tools like [Miri] and [CHERI].
+//!
+//! Exposed Provenance is provided by the [`expose_addr`] and [`from_exposed_addr`] methods, which
+//! are meant to replace `as` casts between pointers and integers. [`expose_addr`] is a lot like
 //! [`addr`], but additionally adds the provenance of the pointer to a global list of 'exposed'
 //! provenances. (This list is purely conceptual, it exists for the purpose of specifying Rust but
 //! is not materialized in actual executions, except in tools like [Miri].) [`from_exposed_addr`]
@@ -341,10 +349,11 @@
 //! there is *no* previously 'exposed' provenance that justifies the way the returned pointer will
 //! be used, the program has undefined behavior.
 //!
-//! Using [`expose_addr`] or [`from_exposed_addr`] (or the equivalent `as` casts) means that code is
+//! Using [`expose_addr`] or [`from_exposed_addr`] (or the `as` casts) means that code is
 //! *not* following Strict Provenance rules. The goal of the Strict Provenance experiment is to
-//! determine whether it is possible to use Rust without [`expose_addr`] and [`from_exposed_addr`].
-//! If this is successful, it would be a major win for avoiding specification complexity and to
+//! determine how far one can get in Rust without the use of [`expose_addr`] and
+//! [`from_exposed_addr`], and to encourage code to be written with Strict Provenance APIs only.
+//! Maximizing the amount of such code is a major win for avoiding specification complexity and to
 //! facilitate adoption of tools like [CHERI] and [Miri] that can be a big help in increasing the
 //! confidence in (unsafe) Rust code.
 //!
@@ -619,12 +628,12 @@ pub const fn invalid_mut<T>(addr: usize) -> *mut T {
 
 /// Convert an address back to a pointer, picking up a previously 'exposed' provenance.
 ///
-/// This is equivalent to `addr as *const T`. The provenance of the returned pointer is that of *any*
-/// pointer that was previously exposed by passing it to [`expose_addr`][pointer::expose_addr],
-/// or a `ptr as usize` cast. In addition, memory which is outside the control of the Rust abstract
-/// machine (MMIO registers, for example) is always considered to be exposed, so long as this memory
-/// is disjoint from memory that will be used by the abstract machine such as the stack, heap,
-/// and statics.
+/// This is a more rigorously specified alternative to `addr as *const T`. The provenance of the
+/// returned pointer is that of *any* pointer that was previously exposed by passing it to
+/// [`expose_addr`][pointer::expose_addr], or a `ptr as usize` cast. In addition, memory which is
+/// outside the control of the Rust abstract machine (MMIO registers, for example) is always
+/// considered to be exposed, so long as this memory is disjoint from memory that will be used by
+/// the abstract machine such as the stack, heap, and statics.
 ///
 /// If there is no 'exposed' provenance that justifies the way this pointer will be used,
 /// the program has undefined behavior. In particular, the aliasing rules still apply: pointers
@@ -639,7 +648,8 @@ pub const fn invalid_mut<T>(addr: usize) -> *mut T {
 /// On platforms with multiple address spaces, it is your responsibility to ensure that the
 /// address makes sense in the address space that this pointer will be used with.
 ///
-/// Using this method means that code is *not* following strict provenance rules. "Guessing" a
+/// Using this function means that code is *not* following [Strict
+/// Provenance][../index.html#strict-provenance] rules. "Guessing" a
 /// suitable provenance complicates specification and reasoning and may not be supported by
 /// tools that help you to stay conformant with the Rust memory model, so it is recommended to
 /// use [`with_addr`][pointer::with_addr] wherever possible.
@@ -649,13 +659,13 @@ pub const fn invalid_mut<T>(addr: usize) -> *mut T {
 /// since it is generally not possible to actually *compute* which provenance the returned
 /// pointer has to pick up.
 ///
-/// This API and its claimed semantics are part of the Strict Provenance experiment, see the
-/// [module documentation][crate::ptr] for details.
+/// It is unclear whether this function can be given a satisfying unambiguous specification. This
+/// API and its claimed semantics are part of [Exposed Provenance][../index.html#exposed-provenance].
 #[must_use]
 #[inline(always)]
-#[unstable(feature = "strict_provenance", issue = "95228")]
+#[unstable(feature = "exposed_provenance", issue = "95228")]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
-#[allow(fuzzy_provenance_casts)] // this *is* the strict provenance API one should use instead
+#[allow(fuzzy_provenance_casts)] // this *is* the explicit provenance API one should use instead
 pub fn from_exposed_addr<T>(addr: usize) -> *const T
 where
     T: Sized,
@@ -666,18 +676,20 @@ where
 
 /// Convert an address back to a mutable pointer, picking up a previously 'exposed' provenance.
 ///
-/// This is equivalent to `addr as *mut T`. The provenance of the returned pointer is that of *any*
-/// pointer that was previously passed to [`expose_addr`][pointer::expose_addr] or a `ptr as usize`
-/// cast. If there is no previously 'exposed' provenance that justifies the way this pointer will be
-/// used, the program has undefined behavior. Note that there is no algorithm that decides which
-/// provenance will be used. You can think of this as "guessing" the right provenance, and the guess
-/// will be "maximally in your favor", in the sense that if there is any way to avoid undefined
-/// behavior, then that is the guess that will be taken.
+/// This is a more rigorously specified alternative to `addr as *mut T`. The provenance of the
+/// returned pointer is that of *any* pointer that was previously passed to
+/// [`expose_addr`][pointer::expose_addr] or a `ptr as usize` cast. If there is no previously
+/// 'exposed' provenance that justifies the way this pointer will be used, the program has undefined
+/// behavior. Note that there is no algorithm that decides which provenance will be used. You can
+/// think of this as "guessing" the right provenance, and the guess will be "maximally in your
+/// favor", in the sense that if there is any way to avoid undefined behavior, then that is the
+/// guess that will be taken.
 ///
 /// On platforms with multiple address spaces, it is your responsibility to ensure that the
 /// address makes sense in the address space that this pointer will be used with.
 ///
-/// Using this method means that code is *not* following strict provenance rules. "Guessing" a
+/// Using this function means that code is *not* following [Strict
+/// Provenance][../index.html#strict-provenance] rules. "Guessing" a
 /// suitable provenance complicates specification and reasoning and may not be supported by
 /// tools that help you to stay conformant with the Rust memory model, so it is recommended to
 /// use [`with_addr`][pointer::with_addr] wherever possible.
@@ -687,13 +699,13 @@ where
 /// since it is generally not possible to actually *compute* which provenance the returned
 /// pointer has to pick up.
 ///
-/// This API and its claimed semantics are part of the Strict Provenance experiment, see the
-/// [module documentation][crate::ptr] for details.
+/// It is unclear whether this function can be given a satisfying unambiguous specification. This
+/// API and its claimed semantics are part of [Exposed Provenance][../index.html#exposed-provenance].
 #[must_use]
 #[inline(always)]
-#[unstable(feature = "strict_provenance", issue = "95228")]
+#[unstable(feature = "exposed_provenance", issue = "95228")]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
-#[allow(fuzzy_provenance_casts)] // this *is* the strict provenance API one should use instead
+#[allow(fuzzy_provenance_casts)] // this *is* the explicit provenance API one should use instead
 pub fn from_exposed_addr_mut<T>(addr: usize) -> *mut T
 where
     T: Sized,
@@ -708,7 +720,8 @@ where
 /// type or mutability, in particular if the code is refactored.
 #[inline(always)]
 #[must_use]
-#[unstable(feature = "ptr_from_ref", issue = "106116")]
+#[stable(feature = "ptr_from_ref", since = "1.76.0")]
+#[rustc_const_stable(feature = "ptr_from_ref", since = "1.76.0")]
 #[rustc_never_returns_null_ptr]
 #[rustc_diagnostic_item = "ptr_from_ref"]
 pub const fn from_ref<T: ?Sized>(r: &T) -> *const T {
@@ -721,7 +734,9 @@ pub const fn from_ref<T: ?Sized>(r: &T) -> *const T {
 /// type or mutability, in particular if the code is refactored.
 #[inline(always)]
 #[must_use]
-#[unstable(feature = "ptr_from_ref", issue = "106116")]
+#[stable(feature = "ptr_from_ref", since = "1.76.0")]
+#[rustc_const_stable(feature = "ptr_from_ref", since = "1.76.0")]
+#[rustc_allow_const_fn_unstable(const_mut_refs)]
 #[rustc_never_returns_null_ptr]
 pub const fn from_mut<T: ?Sized>(r: &mut T) -> *mut T {
     r
@@ -1885,6 +1900,7 @@ pub(crate) const unsafe fn align_offset<T: Sized>(p: *const T, a: usize) -> usiz
 #[inline(always)]
 #[must_use = "pointer comparison produces a value"]
 #[rustc_diagnostic_item = "ptr_eq"]
+#[cfg_attr(not(bootstrap), allow(ambiguous_wide_pointer_comparisons))] // it's actually clear here
 pub fn eq<T: ?Sized>(a: *const T, b: *const T) -> bool {
     a == b
 }
@@ -1898,14 +1914,15 @@ pub fn eq<T: ?Sized>(a: *const T, b: *const T) -> bool {
 /// # Examples
 ///
 /// ```
-/// #![feature(ptr_addr_eq)]
+/// use std::ptr;
 ///
 /// let whole: &[i32; 3] = &[1, 2, 3];
 /// let first: &i32 = &whole[0];
-/// assert!(std::ptr::addr_eq(whole, first));
-/// assert!(!std::ptr::eq::<dyn std::fmt::Debug>(whole, first));
+///
+/// assert!(ptr::addr_eq(whole, first));
+/// assert!(!ptr::eq::<dyn std::fmt::Debug>(whole, first));
 /// ```
-#[unstable(feature = "ptr_addr_eq", issue = "116324")]
+#[stable(feature = "ptr_addr_eq", since = "1.76.0")]
 #[inline(always)]
 #[must_use = "pointer comparison produces a value"]
 pub fn addr_eq<T: ?Sized, U: ?Sized>(p: *const T, q: *const U) -> bool {
@@ -1921,8 +1938,7 @@ pub fn addr_eq<T: ?Sized, U: ?Sized>(p: *const T, q: *const U) -> bool {
 /// # Examples
 ///
 /// ```
-/// use std::collections::hash_map::DefaultHasher;
-/// use std::hash::{Hash, Hasher};
+/// use std::hash::{DefaultHasher, Hash, Hasher};
 /// use std::ptr;
 ///
 /// let five = 5;
diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs
index bc362fb62..9e7b8ec64 100644
--- a/library/core/src/ptr/mut_ptr.rs
+++ b/library/core/src/ptr/mut_ptr.rs
@@ -1,6 +1,6 @@
 use super::*;
-use crate::cmp::Ordering::{self, Equal, Greater, Less};
-use crate::intrinsics::{self, const_eval_select};
+use crate::cmp::Ordering::{Equal, Greater, Less};
+use crate::intrinsics::const_eval_select;
 use crate::mem::SizedTypeProperties;
 use crate::slice::{self, SliceIndex};
 
@@ -193,10 +193,10 @@ impl<T: ?Sized> *mut T {
     /// [`with_addr`][pointer::with_addr] or [`map_addr`][pointer::map_addr].
     ///
     /// If using those APIs is not possible because there is no way to preserve a pointer with the
-    /// required provenance, use [`expose_addr`][pointer::expose_addr] and
-    /// [`from_exposed_addr_mut`][from_exposed_addr_mut] instead. However, note that this makes
-    /// your code less portable and less amenable to tools that check for compliance with the Rust
-    /// memory model.
+    /// required provenance, then Strict Provenance might not be for you. Use pointer-integer casts
+    /// or [`expose_addr`][pointer::expose_addr] and [`from_exposed_addr`][from_exposed_addr]
+    /// instead. However, note that this makes your code less portable and less amenable to tools
+    /// that check for compliance with the Rust memory model.
     ///
     /// On most platforms this will produce a value with the same bytes as the original
     /// pointer, because all the bytes are dedicated to describing the address.
@@ -226,7 +226,8 @@ impl<T: ?Sized> *mut T {
     /// later call [`from_exposed_addr_mut`][] to reconstitute the original pointer including its
     /// provenance. (Reconstructing address space information, if required, is your responsibility.)
     ///
-    /// Using this method means that code is *not* following Strict Provenance rules. Supporting
+    /// Using this method means that code is *not* following [Strict
+    /// Provenance][../index.html#strict-provenance] rules. Supporting
     /// [`from_exposed_addr_mut`][] complicates specification and reasoning and may not be supported
     /// by tools that help you to stay conformant with the Rust memory model, so it is recommended
     /// to use [`addr`][pointer::addr] wherever possible.
@@ -237,13 +238,13 @@ impl<T: ?Sized> *mut T {
     /// side-effect which is required for [`from_exposed_addr_mut`][] to work is typically not
     /// available.
     ///
-    /// This API and its claimed semantics are part of the Strict Provenance experiment, see the
-    /// [module documentation][crate::ptr] for details.
+    /// It is unclear whether this method can be given a satisfying unambiguous specification. This
+    /// API and its claimed semantics are part of [Exposed Provenance][../index.html#exposed-provenance].
     ///
     /// [`from_exposed_addr_mut`]: from_exposed_addr_mut
     #[must_use]
     #[inline(always)]
-    #[unstable(feature = "strict_provenance", issue = "95228")]
+    #[unstable(feature = "exposed_provenance", issue = "95228")]
     pub fn expose_addr(self) -> usize {
         // FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
         self.cast::<()>() as usize
@@ -259,7 +260,7 @@ impl<T: ?Sized> *mut T {
     /// This is equivalent to using [`wrapping_offset`][pointer::wrapping_offset] to offset
     /// `self` to the given address, and therefore has all the same capabilities and restrictions.
     ///
-    /// This API and its claimed semantics are part of the Strict Provenance experiment,
+    /// This API and its claimed semantics are an extension to the Strict Provenance experiment,
     /// see the [module documentation][crate::ptr] for details.
     #[must_use]
     #[inline]
@@ -1634,10 +1635,19 @@ impl<T: ?Sized> *mut T {
             panic!("align_offset: align is not a power-of-two");
         }
 
-        {
-            // SAFETY: `align` has been checked to be a power of 2 above
-            unsafe { align_offset(self, align) }
+        // SAFETY: `align` has been checked to be a power of 2 above
+        let ret = unsafe { align_offset(self, align) };
+
+        // Inform Miri that we want to consider the resulting pointer to be suitably aligned.
+        #[cfg(miri)]
+        if ret != usize::MAX {
+            intrinsics::miri_promise_symbolic_alignment(
+                self.wrapping_add(ret).cast_const().cast(),
+                align,
+            );
         }
+
+        ret
     }
 
     /// Returns whether the pointer is properly aligned for `T`.
@@ -1920,10 +1930,10 @@ impl<T> *mut [T] {
     ///
     /// ```
     /// #![feature(slice_ptr_len)]
+    /// use std::ptr;
     ///
-    /// let mut a = [1, 2, 3];
-    /// let ptr = &mut a as *mut [_];
-    /// assert!(!ptr.is_empty());
+    /// let slice: *mut [i8] = ptr::slice_from_raw_parts_mut(ptr::null_mut(), 3);
+    /// assert!(!slice.is_empty());
     /// ```
     #[inline(always)]
     #[unstable(feature = "slice_ptr_len", issue = "71146")]
@@ -2189,6 +2199,7 @@ impl<T> *mut [T] {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> PartialEq for *mut T {
     #[inline(always)]
+    #[cfg_attr(not(bootstrap), allow(ambiguous_wide_pointer_comparisons))]
     fn eq(&self, other: &*mut T) -> bool {
         *self == *other
     }
@@ -2200,6 +2211,7 @@ impl<T: ?Sized> Eq for *mut T {}
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> Ord for *mut T {
     #[inline]
+    #[cfg_attr(not(bootstrap), allow(ambiguous_wide_pointer_comparisons))]
     fn cmp(&self, other: &*mut T) -> Ordering {
         if self < other {
             Less
@@ -2219,21 +2231,25 @@ impl<T: ?Sized> PartialOrd for *mut T {
     }
 
     #[inline(always)]
+    #[cfg_attr(not(bootstrap), allow(ambiguous_wide_pointer_comparisons))]
     fn lt(&self, other: &*mut T) -> bool {
         *self < *other
     }
 
     #[inline(always)]
+    #[cfg_attr(not(bootstrap), allow(ambiguous_wide_pointer_comparisons))]
     fn le(&self, other: &*mut T) -> bool {
         *self <= *other
     }
 
     #[inline(always)]
+    #[cfg_attr(not(bootstrap), allow(ambiguous_wide_pointer_comparisons))]
     fn gt(&self, other: &*mut T) -> bool {
         *self > *other
     }
 
     #[inline(always)]
+    #[cfg_attr(not(bootstrap), allow(ambiguous_wide_pointer_comparisons))]
     fn ge(&self, other: &*mut T) -> bool {
         *self >= *other
     }
diff --git a/library/core/src/ptr/non_null.rs b/library/core/src/ptr/non_null.rs
index ae673b779..77961506e 100644
--- a/library/core/src/ptr/non_null.rs
+++ b/library/core/src/ptr/non_null.rs
@@ -1,12 +1,14 @@
 use crate::cmp::Ordering;
-use crate::convert::From;
 use crate::fmt;
 use crate::hash;
+use crate::intrinsics;
 use crate::intrinsics::assert_unsafe_precondition;
 use crate::marker::Unsize;
+use crate::mem::SizedTypeProperties;
 use crate::mem::{self, MaybeUninit};
 use crate::num::NonZeroUsize;
 use crate::ops::{CoerceUnsized, DispatchFromDyn};
+use crate::ptr;
 use crate::ptr::Unique;
 use crate::slice::{self, SliceIndex};
 
@@ -471,41 +473,1047 @@ impl<T: ?Sized> NonNull<T> {
         unsafe { NonNull::new_unchecked(self.as_ptr() as *mut U) }
     }
 
-    /// See [`pointer::add`] for semantics and safety requirements.
+    /// Calculates the offset from a pointer.
+    ///
+    /// `count` is in units of T; e.g., a `count` of 3 represents a pointer
+    /// offset of `3 * size_of::<T>()` bytes.
+    ///
+    /// # Safety
+    ///
+    /// If any of the following conditions are violated, the result is Undefined
+    /// Behavior:
+    ///
+    /// * Both the starting and resulting pointer must be either in bounds or one
+    ///   byte past the end of the same [allocated object].
+    ///
+    /// * The computed offset, **in bytes**, cannot overflow an `isize`.
+    ///
+    /// * The offset being in bounds cannot rely on "wrapping around" the address
+    ///   space. That is, the infinite-precision sum, **in bytes** must fit in a usize.
+    ///
+    /// The compiler and standard library generally tries to ensure allocations
+    /// never reach a size where an offset is a concern. For instance, `Vec`
+    /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so
+    /// `vec.as_ptr().add(vec.len())` is always safe.
+    ///
+    /// Most platforms fundamentally can't even construct such an allocation.
+    /// For instance, no known 64-bit platform can ever serve a request
+    /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space.
+    /// However, some 32-bit and 16-bit platforms may successfully serve a request for
+    /// more than `isize::MAX` bytes with things like Physical Address
+    /// Extension. As such, memory acquired directly from allocators or memory
+    /// mapped files *may* be too large to handle with this function.
+    ///
+    /// [allocated object]: crate::ptr#allocated-object
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(non_null_convenience)]
+    /// use std::ptr::NonNull;
+    ///
+    /// let mut s = [1, 2, 3];
+    /// let ptr: NonNull<u32> = NonNull::new(s.as_mut_ptr()).unwrap();
+    ///
+    /// unsafe {
+    ///     println!("{}", ptr.offset(1).read());
+    ///     println!("{}", ptr.offset(2).read());
+    /// }
+    /// ```
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    #[must_use = "returns a new pointer rather than modifying its argument"]
+    #[inline(always)]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn offset(self, count: isize) -> NonNull<T>
+    where
+        T: Sized,
+    {
+        // SAFETY: the caller must uphold the safety contract for `offset`.
+        // Additionally safety contract of `offset` guarantees that the resulting pointer is
+        // pointing to an allocation, there can't be an allocation at null, thus it's safe to
+        // construct `NonNull`.
+        unsafe { NonNull { pointer: intrinsics::offset(self.pointer, count) } }
+    }
+
+    /// Calculates the offset from a pointer in bytes.
+    ///
+    /// `count` is in units of **bytes**.
+    ///
+    /// This is purely a convenience for casting to a `u8` pointer and
+    /// using [offset][pointer::offset] on it. See that method for documentation
+    /// and safety requirements.
+    ///
+    /// For non-`Sized` pointees this operation changes only the data pointer,
+    /// leaving the metadata untouched.
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    #[must_use]
+    #[inline(always)]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn byte_offset(self, count: isize) -> Self {
+        // SAFETY: the caller must uphold the safety contract for `offset` and `byte_offset` has
+        // the same safety contract.
+        // Additionally safety contract of `offset` guarantees that the resulting pointer is
+        // pointing to an allocation, there can't be an allocation at null, thus it's safe to
+        // construct `NonNull`.
+        unsafe { NonNull { pointer: self.pointer.byte_offset(count) } }
+    }
+
+    /// Calculates the offset from a pointer (convenience for `.offset(count as isize)`).
+    ///
+    /// `count` is in units of T; e.g., a `count` of 3 represents a pointer
+    /// offset of `3 * size_of::<T>()` bytes.
+    ///
+    /// # Safety
+    ///
+    /// If any of the following conditions are violated, the result is Undefined
+    /// Behavior:
+    ///
+    /// * Both the starting and resulting pointer must be either in bounds or one
+    ///   byte past the end of the same [allocated object].
+    ///
+    /// * The computed offset, **in bytes**, cannot overflow an `isize`.
+    ///
+    /// * The offset being in bounds cannot rely on "wrapping around" the address
+    ///   space. That is, the infinite-precision sum must fit in a `usize`.
+    ///
+    /// The compiler and standard library generally tries to ensure allocations
+    /// never reach a size where an offset is a concern. For instance, `Vec`
+    /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so
+    /// `vec.as_ptr().add(vec.len())` is always safe.
+    ///
+    /// Most platforms fundamentally can't even construct such an allocation.
+    /// For instance, no known 64-bit platform can ever serve a request
+    /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space.
+    /// However, some 32-bit and 16-bit platforms may successfully serve a request for
+    /// more than `isize::MAX` bytes with things like Physical Address
+    /// Extension. As such, memory acquired directly from allocators or memory
+    /// mapped files *may* be too large to handle with this function.
+    ///
+    /// [allocated object]: crate::ptr#allocated-object
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(non_null_convenience)]
+    /// use std::ptr::NonNull;
+    ///
+    /// let s: &str = "123";
+    /// let ptr: NonNull<u8> = NonNull::new(s.as_ptr().cast_mut()).unwrap();
+    ///
+    /// unsafe {
+    ///     println!("{}", ptr.add(1).read() as char);
+    ///     println!("{}", ptr.add(2).read() as char);
+    /// }
+    /// ```
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    #[must_use = "returns a new pointer rather than modifying its argument"]
+    #[inline(always)]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn add(self, count: usize) -> Self
+    where
+        T: Sized,
+    {
+        // SAFETY: the caller must uphold the safety contract for `offset`.
+        // Additionally safety contract of `offset` guarantees that the resulting pointer is
+        // pointing to an allocation, there can't be an allocation at null, thus it's safe to
+        // construct `NonNull`.
+        unsafe { NonNull { pointer: intrinsics::offset(self.pointer, count) } }
+    }
+
+    /// Calculates the offset from a pointer in bytes (convenience for `.byte_offset(count as isize)`).
+    ///
+    /// `count` is in units of bytes.
+    ///
+    /// This is purely a convenience for casting to a `u8` pointer and
+    /// using [`add`][NonNull::add] on it. See that method for documentation
+    /// and safety requirements.
+    ///
+    /// For non-`Sized` pointees this operation changes only the data pointer,
+    /// leaving the metadata untouched.
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    #[must_use]
+    #[inline(always)]
+    #[rustc_allow_const_fn_unstable(set_ptr_value)]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn byte_add(self, count: usize) -> Self {
+        // SAFETY: the caller must uphold the safety contract for `add` and `byte_add` has the same
+        // safety contract.
+        // Additionally safety contract of `add` guarantees that the resulting pointer is pointing
+        // to an allocation, there can't be an allocation at null, thus it's safe to construct
+        // `NonNull`.
+        unsafe { NonNull { pointer: self.pointer.byte_add(count) } }
+    }
+
+    /// Calculates the offset from a pointer (convenience for
+    /// `.offset((count as isize).wrapping_neg())`).
+    ///
+    /// `count` is in units of T; e.g., a `count` of 3 represents a pointer
+    /// offset of `3 * size_of::<T>()` bytes.
+    ///
+    /// # Safety
+    ///
+    /// If any of the following conditions are violated, the result is Undefined
+    /// Behavior:
+    ///
+    /// * Both the starting and resulting pointer must be either in bounds or one
+    ///   byte past the end of the same [allocated object].
+    ///
+    /// * The computed offset cannot exceed `isize::MAX` **bytes**.
+    ///
+    /// * The offset being in bounds cannot rely on "wrapping around" the address
+    ///   space. That is, the infinite-precision sum must fit in a usize.
+    ///
+    /// The compiler and standard library generally tries to ensure allocations
+    /// never reach a size where an offset is a concern. For instance, `Vec`
+    /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so
+    /// `vec.as_ptr().add(vec.len()).sub(vec.len())` is always safe.
+    ///
+    /// Most platforms fundamentally can't even construct such an allocation.
+    /// For instance, no known 64-bit platform can ever serve a request
+    /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space.
+    /// However, some 32-bit and 16-bit platforms may successfully serve a request for
+    /// more than `isize::MAX` bytes with things like Physical Address
+    /// Extension. As such, memory acquired directly from allocators or memory
+    /// mapped files *may* be too large to handle with this function.
+    ///
+    /// [allocated object]: crate::ptr#allocated-object
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(non_null_convenience)]
+    /// use std::ptr::NonNull;
+    ///
+    /// let s: &str = "123";
+    ///
+    /// unsafe {
+    ///     let end: NonNull<u8> = NonNull::new(s.as_ptr().cast_mut()).unwrap().add(3);
+    ///     println!("{}", end.sub(1).read() as char);
+    ///     println!("{}", end.sub(2).read() as char);
+    /// }
+    /// ```
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    #[must_use = "returns a new pointer rather than modifying its argument"]
+    // We could always go back to wrapping if unchecked becomes unacceptable
+    #[rustc_allow_const_fn_unstable(const_int_unchecked_arith)]
+    #[inline(always)]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn sub(self, count: usize) -> Self
+    where
+        T: Sized,
+    {
+        if T::IS_ZST {
+            // Pointer arithmetic does nothing when the pointee is a ZST.
+            self
+        } else {
+            // SAFETY: the caller must uphold the safety contract for `offset`.
+            // Because the pointee is *not* a ZST, that means that `count` is
+            // at most `isize::MAX`, and thus the negation cannot overflow.
+            unsafe { self.offset(intrinsics::unchecked_sub(0, count as isize)) }
+        }
+    }
+
+    /// Calculates the offset from a pointer in bytes (convenience for
+    /// `.byte_offset((count as isize).wrapping_neg())`).
+    ///
+    /// `count` is in units of bytes.
+    ///
+    /// This is purely a convenience for casting to a `u8` pointer and
+    /// using [`sub`][NonNull::sub] on it. See that method for documentation
+    /// and safety requirements.
+    ///
+    /// For non-`Sized` pointees this operation changes only the data pointer,
+    /// leaving the metadata untouched.
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    #[must_use]
+    #[inline(always)]
+    #[rustc_allow_const_fn_unstable(set_ptr_value)]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn byte_sub(self, count: usize) -> Self {
+        // SAFETY: the caller must uphold the safety contract for `sub` and `byte_sub` has the same
+        // safety contract.
+        // Additionally safety contract of `sub` guarantees that the resulting pointer is pointing
+        // to an allocation, there can't be an allocation at null, thus it's safe to construct
+        // `NonNull`.
+        unsafe { NonNull { pointer: self.pointer.byte_sub(count) } }
+    }
+
+    /// Calculates the distance between two pointers. The returned value is in
+    /// units of T: the distance in bytes divided by `mem::size_of::<T>()`.
+    ///
+    /// This is equivalent to `(self as isize - origin as isize) / (mem::size_of::<T>() as isize)`,
+    /// except that it has a lot more opportunities for UB, in exchange for the compiler
+    /// better understanding what you are doing.
+    ///
+    /// The primary motivation of this method is for computing the `len` of an array/slice
+    /// of `T` that you are currently representing as a "start" and "end" pointer
+    /// (and "end" is "one past the end" of the array).
+    /// In that case, `end.offset_from(start)` gets you the length of the array.
+    ///
+    /// All of the following safety requirements are trivially satisfied for this usecase.
+    ///
+    /// [`offset`]: #method.offset
+    ///
+    /// # Safety
+    ///
+    /// If any of the following conditions are violated, the result is Undefined
+    /// Behavior:
+    ///
+    /// * Both `self` and `origin` must be either in bounds or one
+    ///   byte past the end of the same [allocated object].
+    ///
+    /// * Both pointers must be *derived from* a pointer to the same object.
+    ///   (See below for an example.)
+    ///
+    /// * The distance between the pointers, in bytes, must be an exact multiple
+    ///   of the size of `T`.
+    ///
+    /// * The distance between the pointers, **in bytes**, cannot overflow an `isize`.
+    ///
+    /// * The distance being in bounds cannot rely on "wrapping around" the address space.
+    ///
+    /// Rust types are never larger than `isize::MAX` and Rust allocations never wrap around the
+    /// address space, so two pointers within some value of any Rust type `T` will always satisfy
+    /// the last two conditions. The standard library also generally ensures that allocations
+    /// never reach a size where an offset is a concern. For instance, `Vec` and `Box` ensure they
+    /// never allocate more than `isize::MAX` bytes, so `ptr_into_vec.offset_from(vec.as_ptr())`
+    /// always satisfies the last two conditions.
+    ///
+    /// Most platforms fundamentally can't even construct such a large allocation.
+    /// For instance, no known 64-bit platform can ever serve a request
+    /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space.
+    /// However, some 32-bit and 16-bit platforms may successfully serve a request for
+    /// more than `isize::MAX` bytes with things like Physical Address
+    /// Extension. As such, memory acquired directly from allocators or memory
+    /// mapped files *may* be too large to handle with this function.
+    /// (Note that [`offset`] and [`add`] also have a similar limitation and hence cannot be used on
+    /// such large allocations either.)
+    ///
+    /// The requirement for pointers to be derived from the same allocated object is primarily
+    /// needed for `const`-compatibility: the distance between pointers into *different* allocated
+    /// objects is not known at compile-time. However, the requirement also exists at
+    /// runtime and may be exploited by optimizations. If you wish to compute the difference between
+    /// pointers that are not guaranteed to be from the same allocation, use `(self as isize -
+    /// origin as isize) / mem::size_of::<T>()`.
+    // FIXME: recommend `addr()` instead of `as usize` once that is stable.
+    ///
+    /// [`add`]: #method.add
+    /// [allocated object]: crate::ptr#allocated-object
+    ///
+    /// # Panics
+    ///
+    /// This function panics if `T` is a Zero-Sized Type ("ZST").
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// #![feature(non_null_convenience)]
+    /// use std::ptr::NonNull;
+    ///
+    /// let a = [0; 5];
+    /// let ptr1: NonNull<u32> = NonNull::from(&a[1]);
+    /// let ptr2: NonNull<u32> = NonNull::from(&a[3]);
+    /// unsafe {
+    ///     assert_eq!(ptr2.offset_from(ptr1), 2);
+    ///     assert_eq!(ptr1.offset_from(ptr2), -2);
+    ///     assert_eq!(ptr1.offset(2), ptr2);
+    ///     assert_eq!(ptr2.offset(-2), ptr1);
+    /// }
+    /// ```
+    ///
+    /// *Incorrect* usage:
+    ///
+    /// ```rust,no_run
+    /// #![feature(non_null_convenience, strict_provenance)]
+    /// use std::ptr::NonNull;
+    ///
+    /// let ptr1 = NonNull::new(Box::into_raw(Box::new(0u8))).unwrap();
+    /// let ptr2 = NonNull::new(Box::into_raw(Box::new(1u8))).unwrap();
+    /// let diff = (ptr2.addr().get() as isize).wrapping_sub(ptr1.addr().get() as isize);
+    /// // Make ptr2_other an "alias" of ptr2, but derived from ptr1.
+    /// let ptr2_other = NonNull::new(ptr1.as_ptr().wrapping_byte_offset(diff)).unwrap();
+    /// assert_eq!(ptr2.addr(), ptr2_other.addr());
+    /// // Since ptr2_other and ptr2 are derived from pointers to different objects,
+    /// // computing their offset is undefined behavior, even though
+    /// // they point to the same address!
+    /// unsafe {
+    ///     let zero = ptr2_other.offset_from(ptr2); // Undefined Behavior
+    /// }
+    /// ```
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    #[inline]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn offset_from(self, origin: NonNull<T>) -> isize
+    where
+        T: Sized,
+    {
+        // SAFETY: the caller must uphold the safety contract for `offset_from`.
+        unsafe { self.pointer.offset_from(origin.pointer) }
+    }
+
+    /// Calculates the distance between two pointers. The returned value is in
+    /// units of **bytes**.
+    ///
+    /// This is purely a convenience for casting to a `u8` pointer and
+    /// using [`offset_from`][NonNull::offset_from] on it. See that method for
+    /// documentation and safety requirements.
+    ///
+    /// For non-`Sized` pointees this operation considers only the data pointers,
+    /// ignoring the metadata.
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    #[inline(always)]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn byte_offset_from<U: ?Sized>(self, origin: NonNull<U>) -> isize {
+        // SAFETY: the caller must uphold the safety contract for `byte_offset_from`.
+        unsafe { self.pointer.byte_offset_from(origin.pointer) }
+    }
+
+    // N.B. `wrapping_offset``, `wrapping_add`, etc are not implemented because they can wrap to null
+
+    /// Calculates the distance between two pointers, *where it's known that
+    /// `self` is equal to or greater than `origin`*. The returned value is in
+    /// units of T: the distance in bytes is divided by `mem::size_of::<T>()`.
+    ///
+    /// This computes the same value that [`offset_from`](#method.offset_from)
+    /// would compute, but with the added precondition that the offset is
+    /// guaranteed to be non-negative.  This method is equivalent to
+    /// `usize::try_from(self.offset_from(origin)).unwrap_unchecked()`,
+    /// but it provides slightly more information to the optimizer, which can
+    /// sometimes allow it to optimize slightly better with some backends.
+    ///
+    /// This method can be though of as recovering the `count` that was passed
+    /// to [`add`](#method.add) (or, with the parameters in the other order,
+    /// to [`sub`](#method.sub)).  The following are all equivalent, assuming
+    /// that their safety preconditions are met:
+    /// ```rust
+    /// # #![feature(non_null_convenience)]
+    /// # unsafe fn blah(ptr: std::ptr::NonNull<u32>, origin: std::ptr::NonNull<u32>, count: usize) -> bool {
+    /// ptr.sub_ptr(origin) == count
+    /// # &&
+    /// origin.add(count) == ptr
+    /// # &&
+    /// ptr.sub(count) == origin
+    /// # }
+    /// ```
+    ///
+    /// # Safety
+    ///
+    /// - The distance between the pointers must be non-negative (`self >= origin`)
+    ///
+    /// - *All* the safety conditions of [`offset_from`](#method.offset_from)
+    ///   apply to this method as well; see it for the full details.
+    ///
+    /// Importantly, despite the return type of this method being able to represent
+    /// a larger offset, it's still *not permitted* to pass pointers which differ
+    /// by more than `isize::MAX` *bytes*.  As such, the result of this method will
+    /// always be less than or equal to `isize::MAX as usize`.
+    ///
+    /// # Panics
+    ///
+    /// This function panics if `T` is a Zero-Sized Type ("ZST").
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(non_null_convenience)]
+    /// use std::ptr::NonNull;
+    ///
+    /// let a = [0; 5];
+    /// let ptr1: NonNull<u32> = NonNull::from(&a[1]);
+    /// let ptr2: NonNull<u32> = NonNull::from(&a[3]);
+    /// unsafe {
+    ///     assert_eq!(ptr2.sub_ptr(ptr1), 2);
+    ///     assert_eq!(ptr1.add(2), ptr2);
+    ///     assert_eq!(ptr2.sub(2), ptr1);
+    ///     assert_eq!(ptr2.sub_ptr(ptr2), 0);
+    /// }
+    ///
+    /// // This would be incorrect, as the pointers are not correctly ordered:
+    /// // ptr1.sub_ptr(ptr2)
+    /// ```
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    // #[unstable(feature = "ptr_sub_ptr", issue = "95892")]
+    // #[rustc_const_unstable(feature = "const_ptr_sub_ptr", issue = "95892")]
+    #[inline]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn sub_ptr(self, subtracted: NonNull<T>) -> usize
+    where
+        T: Sized,
+    {
+        // SAFETY: the caller must uphold the safety contract for `sub_ptr`.
+        unsafe { self.pointer.sub_ptr(subtracted.pointer) }
+    }
+
+    /// Reads the value from `self` without moving it. This leaves the
+    /// memory in `self` unchanged.
+    ///
+    /// See [`ptr::read`] for safety concerns and examples.
+    ///
+    /// [`ptr::read`]: crate::ptr::read()
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    #[inline]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn read(self) -> T
+    where
+        T: Sized,
+    {
+        // SAFETY: the caller must uphold the safety contract for `read`.
+        unsafe { ptr::read(self.pointer) }
+    }
+
+    /// Performs a volatile read of the value from `self` without moving it. This
+    /// leaves the memory in `self` unchanged.
+    ///
+    /// Volatile operations are intended to act on I/O memory, and are guaranteed
+    /// to not be elided or reordered by the compiler across other volatile
+    /// operations.
+    ///
+    /// See [`ptr::read_volatile`] for safety concerns and examples.
+    ///
+    /// [`ptr::read_volatile`]: crate::ptr::read_volatile()
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
     #[inline]
-    pub(crate) const unsafe fn add(self, delta: usize) -> Self
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub unsafe fn read_volatile(self) -> T
     where
         T: Sized,
     {
-        // SAFETY: We require that the delta stays in-bounds of the object, and
-        // thus it cannot become null, as that would require wrapping the
-        // address space, which no legal objects are allowed to do.
-        // And the caller promised the `delta` is sound to add.
-        unsafe { NonNull { pointer: self.pointer.add(delta) } }
+        // SAFETY: the caller must uphold the safety contract for `read_volatile`.
+        unsafe { ptr::read_volatile(self.pointer) }
     }
 
-    /// See [`pointer::sub`] for semantics and safety requirements.
+    /// Reads the value from `self` without moving it. This leaves the
+    /// memory in `self` unchanged.
+    ///
+    /// Unlike `read`, the pointer may be unaligned.
+    ///
+    /// See [`ptr::read_unaligned`] for safety concerns and examples.
+    ///
+    /// [`ptr::read_unaligned`]: crate::ptr::read_unaligned()
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
     #[inline]
-    pub(crate) const unsafe fn sub(self, delta: usize) -> Self
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn read_unaligned(self) -> T
+    where
+        T: Sized,
+    {
+        // SAFETY: the caller must uphold the safety contract for `read_unaligned`.
+        unsafe { ptr::read_unaligned(self.pointer) }
+    }
+
+    /// Copies `count * size_of<T>` bytes from `self` to `dest`. The source
+    /// and destination may overlap.
+    ///
+    /// NOTE: this has the *same* argument order as [`ptr::copy`].
+    ///
+    /// See [`ptr::copy`] for safety concerns and examples.
+    ///
+    /// [`ptr::copy`]: crate::ptr::copy()
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    #[inline(always)]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn copy_to(self, dest: NonNull<T>, count: usize)
+    where
+        T: Sized,
+    {
+        // SAFETY: the caller must uphold the safety contract for `copy`.
+        unsafe { ptr::copy(self.pointer, dest.as_ptr(), count) }
+    }
+
+    /// Copies `count * size_of<T>` bytes from `self` to `dest`. The source
+    /// and destination may *not* overlap.
+    ///
+    /// NOTE: this has the *same* argument order as [`ptr::copy_nonoverlapping`].
+    ///
+    /// See [`ptr::copy_nonoverlapping`] for safety concerns and examples.
+    ///
+    /// [`ptr::copy_nonoverlapping`]: crate::ptr::copy_nonoverlapping()
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    #[inline(always)]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn copy_to_nonoverlapping(self, dest: NonNull<T>, count: usize)
+    where
+        T: Sized,
+    {
+        // SAFETY: the caller must uphold the safety contract for `copy_nonoverlapping`.
+        unsafe { ptr::copy_nonoverlapping(self.pointer, dest.as_ptr(), count) }
+    }
+
+    /// Copies `count * size_of<T>` bytes from `src` to `self`. The source
+    /// and destination may overlap.
+    ///
+    /// NOTE: this has the *opposite* argument order of [`ptr::copy`].
+    ///
+    /// See [`ptr::copy`] for safety concerns and examples.
+    ///
+    /// [`ptr::copy`]: crate::ptr::copy()
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    #[inline(always)]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn copy_from(self, src: NonNull<T>, count: usize)
+    where
+        T: Sized,
+    {
+        // SAFETY: the caller must uphold the safety contract for `copy`.
+        unsafe { ptr::copy(src.pointer, self.as_ptr(), count) }
+    }
+
+    /// Copies `count * size_of<T>` bytes from `src` to `self`. The source
+    /// and destination may *not* overlap.
+    ///
+    /// NOTE: this has the *opposite* argument order of [`ptr::copy_nonoverlapping`].
+    ///
+    /// See [`ptr::copy_nonoverlapping`] for safety concerns and examples.
+    ///
+    /// [`ptr::copy_nonoverlapping`]: crate::ptr::copy_nonoverlapping()
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    #[inline(always)]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn copy_from_nonoverlapping(self, src: NonNull<T>, count: usize)
+    where
+        T: Sized,
+    {
+        // SAFETY: the caller must uphold the safety contract for `copy_nonoverlapping`.
+        unsafe { ptr::copy_nonoverlapping(src.pointer, self.as_ptr(), count) }
+    }
+
+    /// Executes the destructor (if any) of the pointed-to value.
+    ///
+    /// See [`ptr::drop_in_place`] for safety concerns and examples.
+    ///
+    /// [`ptr::drop_in_place`]: crate::ptr::drop_in_place()
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[inline(always)]
+    pub unsafe fn drop_in_place(self) {
+        // SAFETY: the caller must uphold the safety contract for `drop_in_place`.
+        unsafe { ptr::drop_in_place(self.as_ptr()) }
+    }
+
+    /// Overwrites a memory location with the given value without reading or
+    /// dropping the old value.
+    ///
+    /// See [`ptr::write`] for safety concerns and examples.
+    ///
+    /// [`ptr::write`]: crate::ptr::write()
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    //#[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[inline(always)]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn write(self, val: T)
+    where
+        T: Sized,
+    {
+        // SAFETY: the caller must uphold the safety contract for `write`.
+        unsafe { ptr::write(self.as_ptr(), val) }
+    }
+
+    /// Invokes memset on the specified pointer, setting `count * size_of::<T>()`
+    /// bytes of memory starting at `self` to `val`.
+    ///
+    /// See [`ptr::write_bytes`] for safety concerns and examples.
+    ///
+    /// [`ptr::write_bytes`]: crate::ptr::write_bytes()
+    #[doc(alias = "memset")]
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    //#[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[inline(always)]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn write_bytes(self, val: u8, count: usize)
+    where
+        T: Sized,
+    {
+        // SAFETY: the caller must uphold the safety contract for `write_bytes`.
+        unsafe { ptr::write_bytes(self.as_ptr(), val, count) }
+    }
+
+    /// Performs a volatile write of a memory location with the given value without
+    /// reading or dropping the old value.
+    ///
+    /// Volatile operations are intended to act on I/O memory, and are guaranteed
+    /// to not be elided or reordered by the compiler across other volatile
+    /// operations.
+    ///
+    /// See [`ptr::write_volatile`] for safety concerns and examples.
+    ///
+    /// [`ptr::write_volatile`]: crate::ptr::write_volatile()
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[inline(always)]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub unsafe fn write_volatile(self, val: T)
+    where
+        T: Sized,
+    {
+        // SAFETY: the caller must uphold the safety contract for `write_volatile`.
+        unsafe { ptr::write_volatile(self.as_ptr(), val) }
+    }
+
+    /// Overwrites a memory location with the given value without reading or
+    /// dropping the old value.
+    ///
+    /// Unlike `write`, the pointer may be unaligned.
+    ///
+    /// See [`ptr::write_unaligned`] for safety concerns and examples.
+    ///
+    /// [`ptr::write_unaligned`]: crate::ptr::write_unaligned()
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    //#[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[inline(always)]
+    #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
+    pub const unsafe fn write_unaligned(self, val: T)
     where
         T: Sized,
     {
-        // SAFETY: We require that the delta stays in-bounds of the object, and
-        // thus it cannot become null, as no legal objects can be allocated
-        // in such as way that the null address is part of them.
-        // And the caller promised the `delta` is sound to subtract.
-        unsafe { NonNull { pointer: self.pointer.sub(delta) } }
+        // SAFETY: the caller must uphold the safety contract for `write_unaligned`.
+        unsafe { ptr::write_unaligned(self.as_ptr(), val) }
     }
 
-    /// See [`pointer::sub_ptr`] for semantics and safety requirements.
+    /// Replaces the value at `self` with `src`, returning the old
+    /// value, without dropping either.
+    ///
+    /// See [`ptr::replace`] for safety concerns and examples.
+    ///
+    /// [`ptr::replace`]: crate::ptr::replace()
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[inline(always)]
+    pub unsafe fn replace(self, src: T) -> T
+    where
+        T: Sized,
+    {
+        // SAFETY: the caller must uphold the safety contract for `replace`.
+        unsafe { ptr::replace(self.as_ptr(), src) }
+    }
+
+    /// Swaps the values at two mutable locations of the same type, without
+    /// deinitializing either. They may overlap, unlike `mem::swap` which is
+    /// otherwise equivalent.
+    ///
+    /// See [`ptr::swap`] for safety concerns and examples.
+    ///
+    /// [`ptr::swap`]: crate::ptr::swap()
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    //#[rustc_const_unstable(feature = "const_swap", issue = "83163")]
+    #[inline(always)]
+    pub const unsafe fn swap(self, with: NonNull<T>)
+    where
+        T: Sized,
+    {
+        // SAFETY: the caller must uphold the safety contract for `swap`.
+        unsafe { ptr::swap(self.as_ptr(), with.as_ptr()) }
+    }
+
+    /// Computes the offset that needs to be applied to the pointer in order to make it aligned to
+    /// `align`.
+    ///
+    /// If it is not possible to align the pointer, the implementation returns
+    /// `usize::MAX`. It is permissible for the implementation to *always*
+    /// return `usize::MAX`. Only your algorithm's performance can depend
+    /// on getting a usable offset here, not its correctness.
+    ///
+    /// The offset is expressed in number of `T` elements, and not bytes.
+    ///
+    /// There are no guarantees whatsoever that offsetting the pointer will not overflow or go
+    /// beyond the allocation that the pointer points into. It is up to the caller to ensure that
+    /// the returned offset is correct in all terms other than alignment.
+    ///
+    /// # Panics
+    ///
+    /// The function panics if `align` is not a power-of-two.
+    ///
+    /// # Examples
+    ///
+    /// Accessing adjacent `u8` as `u16`
+    ///
+    /// ```
+    /// #![feature(non_null_convenience)]
+    /// use std::mem::align_of;
+    /// use std::ptr::NonNull;
+    ///
+    /// # unsafe {
+    /// let x = [5_u8, 6, 7, 8, 9];
+    /// let ptr = NonNull::new(x.as_ptr() as *mut u8).unwrap();
+    /// let offset = ptr.align_offset(align_of::<u16>());
+    ///
+    /// if offset < x.len() - 1 {
+    ///     let u16_ptr = ptr.add(offset).cast::<u16>();
+    ///     assert!(u16_ptr.read() == u16::from_ne_bytes([5, 6]) || u16_ptr.read() == u16::from_ne_bytes([6, 7]));
+    /// } else {
+    ///     // while the pointer can be aligned via `offset`, it would point
+    ///     // outside the allocation
+    /// }
+    /// # }
+    /// ```
+    #[unstable(feature = "non_null_convenience", issue = "117691")]
+    #[rustc_const_unstable(feature = "non_null_convenience", issue = "117691")]
+    //#[rustc_const_unstable(feature = "const_align_offset", issue = "90962")]
+    #[must_use]
     #[inline]
-    pub(crate) const unsafe fn sub_ptr(self, subtrahend: Self) -> usize
+    pub const fn align_offset(self, align: usize) -> usize
     where
         T: Sized,
     {
-        // SAFETY: The caller promised that this is safe to do, and
-        // the non-nullness is irrelevant to the operation.
-        unsafe { self.pointer.sub_ptr(subtrahend.pointer) }
+        if !align.is_power_of_two() {
+            panic!("align_offset: align is not a power-of-two");
+        }
+
+        {
+            // SAFETY: `align` has been checked to be a power of 2 above.
+            unsafe { ptr::align_offset(self.pointer, align) }
+        }
+    }
+
+    /// Returns whether the pointer is properly aligned for `T`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(pointer_is_aligned)]
+    /// use std::ptr::NonNull;
+    ///
+    /// // On some platforms, the alignment of i32 is less than 4.
+    /// #[repr(align(4))]
+    /// struct AlignedI32(i32);
+    ///
+    /// let data = AlignedI32(42);
+    /// let ptr = NonNull::<AlignedI32>::from(&data);
+    ///
+    /// assert!(ptr.is_aligned());
+    /// assert!(!NonNull::new(ptr.as_ptr().wrapping_byte_add(1)).unwrap().is_aligned());
+    /// ```
+    ///
+    /// # At compiletime
+    /// **Note: Alignment at compiletime is experimental and subject to change. See the
+    /// [tracking issue] for details.**
+    ///
+    /// At compiletime, the compiler may not know where a value will end up in memory.
+    /// Calling this function on a pointer created from a reference at compiletime will only
+    /// return `true` if the pointer is guaranteed to be aligned. This means that the pointer
+    /// is never aligned if cast to a type with a stricter alignment than the reference's
+    /// underlying allocation.
+    ///
+    /// ```
+    /// #![feature(pointer_is_aligned)]
+    /// #![feature(const_pointer_is_aligned)]
+    /// #![feature(non_null_convenience)]
+    /// #![feature(const_option)]
+    /// #![feature(const_nonnull_new)]
+    /// use std::ptr::NonNull;
+    ///
+    /// // On some platforms, the alignment of primitives is less than their size.
+    /// #[repr(align(4))]
+    /// struct AlignedI32(i32);
+    /// #[repr(align(8))]
+    /// struct AlignedI64(i64);
+    ///
+    /// const _: () = {
+    ///     let data = [AlignedI32(42), AlignedI32(42)];
+    ///     let ptr = NonNull::<AlignedI32>::new(&data[0] as *const _ as *mut _).unwrap();
+    ///     assert!(ptr.is_aligned());
+    ///
+    ///     // At runtime either `ptr1` or `ptr2` would be aligned, but at compiletime neither is aligned.
+    ///     let ptr1 = ptr.cast::<AlignedI64>();
+    ///     let ptr2 = unsafe { ptr.add(1).cast::<AlignedI64>() };
+    ///     assert!(!ptr1.is_aligned());
+    ///     assert!(!ptr2.is_aligned());
+    /// };
+    /// ```
+    ///
+    /// Due to this behavior, it is possible that a runtime pointer derived from a compiletime
+    /// pointer is aligned, even if the compiletime pointer wasn't aligned.
+    ///
+    /// ```
+    /// #![feature(pointer_is_aligned)]
+    /// #![feature(const_pointer_is_aligned)]
+    ///
+    /// // On some platforms, the alignment of primitives is less than their size.
+    /// #[repr(align(4))]
+    /// struct AlignedI32(i32);
+    /// #[repr(align(8))]
+    /// struct AlignedI64(i64);
+    ///
+    /// // At compiletime, neither `COMPTIME_PTR` nor `COMPTIME_PTR + 1` is aligned.
+    /// const COMPTIME_PTR: *const AlignedI32 = &AlignedI32(42);
+    /// const _: () = assert!(!COMPTIME_PTR.cast::<AlignedI64>().is_aligned());
+    /// const _: () = assert!(!COMPTIME_PTR.wrapping_add(1).cast::<AlignedI64>().is_aligned());
+    ///
+    /// // At runtime, either `runtime_ptr` or `runtime_ptr + 1` is aligned.
+    /// let runtime_ptr = COMPTIME_PTR;
+    /// assert_ne!(
+    ///     runtime_ptr.cast::<AlignedI64>().is_aligned(),
+    ///     runtime_ptr.wrapping_add(1).cast::<AlignedI64>().is_aligned(),
+    /// );
+    /// ```
+    ///
+    /// If a pointer is created from a fixed address, this function behaves the same during
+    /// runtime and compiletime.
+    ///
+    /// ```
+    /// #![feature(pointer_is_aligned)]
+    /// #![feature(const_pointer_is_aligned)]
+    /// #![feature(const_option)]
+    /// #![feature(const_nonnull_new)]
+    /// use std::ptr::NonNull;
+    ///
+    /// // On some platforms, the alignment of primitives is less than their size.
+    /// #[repr(align(4))]
+    /// struct AlignedI32(i32);
+    /// #[repr(align(8))]
+    /// struct AlignedI64(i64);
+    ///
+    /// const _: () = {
+    ///     let ptr = NonNull::new(40 as *mut AlignedI32).unwrap();
+    ///     assert!(ptr.is_aligned());
+    ///
+    ///     // For pointers with a known address, runtime and compiletime behavior are identical.
+    ///     let ptr1 = ptr.cast::<AlignedI64>();
+    ///     let ptr2 = NonNull::new(ptr.as_ptr().wrapping_add(1)).unwrap().cast::<AlignedI64>();
+    ///     assert!(ptr1.is_aligned());
+    ///     assert!(!ptr2.is_aligned());
+    /// };
+    /// ```
+    ///
+    /// [tracking issue]: https://github.com/rust-lang/rust/issues/104203
+    #[unstable(feature = "pointer_is_aligned", issue = "96284")]
+    #[rustc_const_unstable(feature = "const_pointer_is_aligned", issue = "104203")]
+    #[must_use]
+    #[inline]
+    pub const fn is_aligned(self) -> bool
+    where
+        T: Sized,
+    {
+        self.pointer.is_aligned()
+    }
+
+    /// Returns whether the pointer is aligned to `align`.
+    ///
+    /// For non-`Sized` pointees this operation considers only the data pointer,
+    /// ignoring the metadata.
+    ///
+    /// # Panics
+    ///
+    /// The function panics if `align` is not a power-of-two (this includes 0).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(pointer_is_aligned)]
+    ///
+    /// // On some platforms, the alignment of i32 is less than 4.
+    /// #[repr(align(4))]
+    /// struct AlignedI32(i32);
+    ///
+    /// let data = AlignedI32(42);
+    /// let ptr = &data as *const AlignedI32;
+    ///
+    /// assert!(ptr.is_aligned_to(1));
+    /// assert!(ptr.is_aligned_to(2));
+    /// assert!(ptr.is_aligned_to(4));
+    ///
+    /// assert!(ptr.wrapping_byte_add(2).is_aligned_to(2));
+    /// assert!(!ptr.wrapping_byte_add(2).is_aligned_to(4));
+    ///
+    /// assert_ne!(ptr.is_aligned_to(8), ptr.wrapping_add(1).is_aligned_to(8));
+    /// ```
+    ///
+    /// # At compiletime
+    /// **Note: Alignment at compiletime is experimental and subject to change. See the
+    /// [tracking issue] for details.**
+    ///
+    /// At compiletime, the compiler may not know where a value will end up in memory.
+    /// Calling this function on a pointer created from a reference at compiletime will only
+    /// return `true` if the pointer is guaranteed to be aligned. This means that the pointer
+    /// cannot be stricter aligned than the reference's underlying allocation.
+    ///
+    /// ```
+    /// #![feature(pointer_is_aligned)]
+    /// #![feature(const_pointer_is_aligned)]
+    ///
+    /// // On some platforms, the alignment of i32 is less than 4.
+    /// #[repr(align(4))]
+    /// struct AlignedI32(i32);
+    ///
+    /// const _: () = {
+    ///     let data = AlignedI32(42);
+    ///     let ptr = &data as *const AlignedI32;
+    ///
+    ///     assert!(ptr.is_aligned_to(1));
+    ///     assert!(ptr.is_aligned_to(2));
+    ///     assert!(ptr.is_aligned_to(4));
+    ///
+    ///     // At compiletime, we know for sure that the pointer isn't aligned to 8.
+    ///     assert!(!ptr.is_aligned_to(8));
+    ///     assert!(!ptr.wrapping_add(1).is_aligned_to(8));
+    /// };
+    /// ```
+    ///
+    /// Due to this behavior, it is possible that a runtime pointer derived from a compiletime
+    /// pointer is aligned, even if the compiletime pointer wasn't aligned.
+    ///
+    /// ```
+    /// #![feature(pointer_is_aligned)]
+    /// #![feature(const_pointer_is_aligned)]
+    ///
+    /// // On some platforms, the alignment of i32 is less than 4.
+    /// #[repr(align(4))]
+    /// struct AlignedI32(i32);
+    ///
+    /// // At compiletime, neither `COMPTIME_PTR` nor `COMPTIME_PTR + 1` is aligned.
+    /// const COMPTIME_PTR: *const AlignedI32 = &AlignedI32(42);
+    /// const _: () = assert!(!COMPTIME_PTR.is_aligned_to(8));
+    /// const _: () = assert!(!COMPTIME_PTR.wrapping_add(1).is_aligned_to(8));
+    ///
+    /// // At runtime, either `runtime_ptr` or `runtime_ptr + 1` is aligned.
+    /// let runtime_ptr = COMPTIME_PTR;
+    /// assert_ne!(
+    ///     runtime_ptr.is_aligned_to(8),
+    ///     runtime_ptr.wrapping_add(1).is_aligned_to(8),
+    /// );
+    /// ```
+    ///
+    /// If a pointer is created from a fixed address, this function behaves the same during
+    /// runtime and compiletime.
+    ///
+    /// ```
+    /// #![feature(pointer_is_aligned)]
+    /// #![feature(const_pointer_is_aligned)]
+    ///
+    /// const _: () = {
+    ///     let ptr = 40 as *const u8;
+    ///     assert!(ptr.is_aligned_to(1));
+    ///     assert!(ptr.is_aligned_to(2));
+    ///     assert!(ptr.is_aligned_to(4));
+    ///     assert!(ptr.is_aligned_to(8));
+    ///     assert!(!ptr.is_aligned_to(16));
+    /// };
+    /// ```
+    ///
+    /// [tracking issue]: https://github.com/rust-lang/rust/issues/104203
+    #[unstable(feature = "pointer_is_aligned", issue = "96284")]
+    #[rustc_const_unstable(feature = "const_pointer_is_aligned", issue = "104203")]
+    #[must_use]
+    #[inline]
+    pub const fn is_aligned_to(self, align: usize) -> bool {
+        self.pointer.is_aligned_to(align)
     }
 }
 
@@ -783,6 +1791,7 @@ impl<T: ?Sized> Eq for NonNull<T> {}
 #[stable(feature = "nonnull", since = "1.25.0")]
 impl<T: ?Sized> PartialEq for NonNull<T> {
     #[inline]
+    #[cfg_attr(not(bootstrap), allow(ambiguous_wide_pointer_comparisons))]
     fn eq(&self, other: &Self) -> bool {
         self.as_ptr() == other.as_ptr()
     }
diff --git a/library/core/src/ptr/unique.rs b/library/core/src/ptr/unique.rs
index bf8b86677..067f1541e 100644
--- a/library/core/src/ptr/unique.rs
+++ b/library/core/src/ptr/unique.rs
@@ -1,4 +1,3 @@
-use crate::convert::From;
 use crate::fmt;
 use crate::marker::{PhantomData, Unsize};
 use crate::ops::{CoerceUnsized, DispatchFromDyn};