Importing rustc-1.53.0 Bug: 194400612 Change-Id: Id2f38eeabc8325fff960e46b89b1cc7216f5227c

diff --git a/library/core/Cargo.toml b/library/core/Cargo.toml
index c159601..b6aaf07 100644
--- a/library/core/Cargo.toml
+++ b/library/core/Cargo.toml

@@ -2,6 +2,9 @@
 authors = ["The Rust Project Developers"]
 name = "core"
 version = "0.0.0"
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/rust-lang/rust.git"
+description = "The Rust Core Library"
 autotests = false
 autobenches = false
 edition = "2018"
@@ -25,3 +28,6 @@
 [features]
 # Make panics and failed asserts immediately abort without formatting any message
 panic_immediate_abort = []
+# Make `RefCell` store additional debugging information, which is printed out when
+# a borrow error occurs
+debug_refcell = []

diff --git a/library/core/benches/fmt.rs b/library/core/benches/fmt.rs
index 2792181..9df6626 100644
--- a/library/core/benches/fmt.rs
+++ b/library/core/benches/fmt.rs

@@ -112,7 +112,7 @@
 #[bench]
 fn write_u128_max(bh: &mut Bencher) {
     bh.iter(|| {
-        std::hint::black_box(format!("{}", u128::MAX));
+        test::black_box(format!("{}", u128::MAX));
     });
 }
 
@@ -120,20 +120,20 @@
 fn write_u128_min(bh: &mut Bencher) {
     bh.iter(|| {
         let s = format!("{}", 0u128);
-        std::hint::black_box(s);
+        test::black_box(s);
     });
 }
 
 #[bench]
 fn write_u64_max(bh: &mut Bencher) {
     bh.iter(|| {
-        std::hint::black_box(format!("{}", u64::MAX));
+        test::black_box(format!("{}", u64::MAX));
     });
 }
 
 #[bench]
 fn write_u64_min(bh: &mut Bencher) {
     bh.iter(|| {
-        std::hint::black_box(format!("{}", 0u64));
+        test::black_box(format!("{}", 0u64));
     });
 }

diff --git a/library/core/benches/slice.rs b/library/core/benches/slice.rs
index dbab008..04efa52 100644
--- a/library/core/benches/slice.rs
+++ b/library/core/benches/slice.rs

@@ -114,3 +114,16 @@
 rotate!(rotate_16_usize_5, 16, |i| [i; 5]);
 rotate!(rotate_64_usize_4, 64, |i| [i; 4]);
 rotate!(rotate_64_usize_5, 64, |i| [i; 5]);
+
+#[bench]
+fn fill_byte_sized(b: &mut Bencher) {
+    #[derive(Copy, Clone)]
+    struct NewType(u8);
+
+    let mut ary = [NewType(0); 1024];
+
+    b.iter(|| {
+        let slice = &mut ary[..];
+        black_box(slice.fill(black_box(NewType(42))));
+    });
+}

diff --git a/library/core/src/alloc/layout.rs b/library/core/src/alloc/layout.rs
index 8b95b70..0e7667d 100644
--- a/library/core/src/alloc/layout.rs
+++ b/library/core/src/alloc/layout.rs

@@ -93,7 +93,7 @@
     /// This function is unsafe as it does not verify the preconditions from
     /// [`Layout::from_size_align`].
     #[stable(feature = "alloc_layout", since = "1.28.0")]
-    #[rustc_const_stable(feature = "alloc_layout", since = "1.28.0")]
+    #[rustc_const_stable(feature = "alloc_layout", since = "1.36.0")]
     #[inline]
     pub const unsafe fn from_size_align_unchecked(size: usize, align: usize) -> Self {
         // SAFETY: the caller must ensure that `align` is greater than zero.

diff --git a/library/core/src/any.rs b/library/core/src/any.rs
index 98c34f3..5e1725c 100644
--- a/library/core/src/any.rs
+++ b/library/core/src/any.rs

@@ -141,7 +141,7 @@
 #[stable(feature = "rust1", since = "1.0.0")]
 impl fmt::Debug for dyn Any {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.pad("Any")
+        f.debug_struct("Any").finish_non_exhaustive()
     }
 }
 
@@ -151,14 +151,14 @@
 #[stable(feature = "rust1", since = "1.0.0")]
 impl fmt::Debug for dyn Any + Send {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.pad("Any")
+        f.debug_struct("Any").finish_non_exhaustive()
     }
 }
 
 #[stable(feature = "any_send_sync_methods", since = "1.28.0")]
 impl fmt::Debug for dyn Any + Send + Sync {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.pad("Any")
+        f.debug_struct("Any").finish_non_exhaustive()
     }
 }
 

diff --git a/library/core/src/array/iter.rs b/library/core/src/array/iter.rs
index 4472fba..61ab1b1 100644
--- a/library/core/src/array/iter.rs
+++ b/library/core/src/array/iter.rs

@@ -2,7 +2,7 @@
 
 use crate::{
     fmt,
-    iter::{ExactSizeIterator, FusedIterator, TrustedLen},
+    iter::{self, ExactSizeIterator, FusedIterator, TrustedLen},
     mem::{self, MaybeUninit},
     ops::Range,
     ptr,
@@ -192,7 +192,7 @@
         let mut new = Self { data: MaybeUninit::uninit_array(), alive: 0..0 };
 
         // Clone all alive elements.
-        for (src, dst) in self.as_slice().iter().zip(&mut new.data) {
+        for (src, dst) in iter::zip(self.as_slice(), &mut new.data) {
             // Write a clone into the new array, then update its alive range.
             // If cloning panics, we'll correctly drop the previous items.
             dst.write(src.clone());

diff --git a/library/core/src/array/mod.rs b/library/core/src/array/mod.rs
index 8f52985..8b56c95 100644
--- a/library/core/src/array/mod.rs
+++ b/library/core/src/array/mod.rs

@@ -12,7 +12,6 @@
 use crate::fmt;
 use crate::hash::{self, Hash};
 use crate::iter::TrustedLen;
-use crate::marker::Unsize;
 use crate::mem::{self, MaybeUninit};
 use crate::ops::{Index, IndexMut};
 use crate::slice::{Iter, IterMut};
@@ -23,54 +22,19 @@
 pub use iter::IntoIter;
 
 /// Converts a reference to `T` into a reference to an array of length 1 (without copying).
-#[unstable(feature = "array_from_ref", issue = "77101")]
+#[stable(feature = "array_from_ref", since = "1.53.0")]
 pub fn from_ref<T>(s: &T) -> &[T; 1] {
     // SAFETY: Converting `&T` to `&[T; 1]` is sound.
     unsafe { &*(s as *const T).cast::<[T; 1]>() }
 }
 
 /// Converts a mutable reference to `T` into a mutable reference to an array of length 1 (without copying).
-#[unstable(feature = "array_from_ref", issue = "77101")]
+#[stable(feature = "array_from_ref", since = "1.53.0")]
 pub fn from_mut<T>(s: &mut T) -> &mut [T; 1] {
     // SAFETY: Converting `&mut T` to `&mut [T; 1]` is sound.
     unsafe { &mut *(s as *mut T).cast::<[T; 1]>() }
 }
 
-/// Utility trait implemented only on arrays of fixed size
-///
-/// This trait can be used to implement other traits on fixed-size arrays
-/// without causing much metadata bloat.
-///
-/// The trait is marked unsafe in order to restrict implementors to fixed-size
-/// arrays. A user of this trait can assume that implementors have the exact
-/// layout in memory of a fixed size array (for example, for unsafe
-/// initialization).
-///
-/// Note that the traits [`AsRef`] and [`AsMut`] provide similar methods for types that
-/// may not be fixed-size arrays. Implementors should prefer those traits
-/// instead.
-#[unstable(feature = "fixed_size_array", issue = "27778")]
-pub unsafe trait FixedSizeArray<T> {
-    /// Converts the array to immutable slice
-    #[unstable(feature = "fixed_size_array", issue = "27778")]
-    fn as_slice(&self) -> &[T];
-    /// Converts the array to mutable slice
-    #[unstable(feature = "fixed_size_array", issue = "27778")]
-    fn as_mut_slice(&mut self) -> &mut [T];
-}
-
-#[unstable(feature = "fixed_size_array", issue = "27778")]
-unsafe impl<T, A: Unsize<[T]>> FixedSizeArray<T> for A {
-    #[inline]
-    fn as_slice(&self) -> &[T] {
-        self
-    }
-    #[inline]
-    fn as_mut_slice(&mut self) -> &mut [T] {
-        self
-    }
-}
-
 /// The error type returned when a conversion from a slice to an array fails.
 #[stable(feature = "try_from", since = "1.34.0")]
 #[derive(Debug, Copy, Clone)]
@@ -191,6 +155,28 @@
     }
 }
 
+// Note: the `#[rustc_skip_array_during_method_dispatch]` on `trait IntoIterator`
+// hides this implementation from explicit `.into_iter()` calls on editions < 2021,
+// so those calls will still resolve to the slice implementation, by reference.
+#[cfg(not(bootstrap))]
+#[stable(feature = "array_into_iter_impl", since = "1.53.0")]
+impl<T, const N: usize> IntoIterator for [T; N] {
+    type Item = T;
+    type IntoIter = IntoIter<T, N>;
+
+    /// Creates a consuming iterator, that is, one that moves each value out of
+    /// the array (from start to end). The array cannot be used after calling
+    /// this unless `T` implements `Copy`, so the whole array is copied.
+    ///
+    /// Arrays have special behavior when calling `.into_iter()` prior to the
+    /// 2021 edition -- see the [array] Editions section for more information.
+    ///
+    /// [array]: prim@array
+    fn into_iter(self) -> Self::IntoIter {
+        IntoIter::new(self)
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T, const N: usize> IntoIterator for &'a [T; N] {
     type Item = &'a T;

diff --git a/library/core/src/ascii.rs b/library/core/src/ascii.rs
index a8a25f9..4780d8d 100644
--- a/library/core/src/ascii.rs
+++ b/library/core/src/ascii.rs

@@ -145,6 +145,6 @@
 #[stable(feature = "std_debug", since = "1.16.0")]
 impl fmt::Debug for EscapeDefault {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.pad("EscapeDefault { .. }")
+        f.debug_struct("EscapeDefault").finish_non_exhaustive()
     }
 }

diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs
index 2fbbeb3..4820588 100644
--- a/library/core/src/cell.rs
+++ b/library/core/src/cell.rs

@@ -188,7 +188,7 @@
 //! [`Rc<T>`]: ../../std/rc/struct.Rc.html
 //! [`RwLock<T>`]: ../../std/sync/struct.RwLock.html
 //! [`Mutex<T>`]: ../../std/sync/struct.Mutex.html
-//! [`atomic`]: ../../core/sync/atomic/index.html
+//! [`atomic`]: crate::sync::atomic
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
@@ -325,7 +325,7 @@
     /// let c = Cell::new(5);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_cell_new", since = "1.32.0")]
+    #[rustc_const_stable(feature = "const_cell_new", since = "1.24.0")]
     #[inline]
     pub const fn new(value: T) -> Cell<T> {
         Cell { value: UnsafeCell::new(value) }
@@ -575,6 +575,12 @@
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct RefCell<T: ?Sized> {
     borrow: Cell<BorrowFlag>,
+    // Stores the location of the earliest currently active borrow.
+    // This gets updated whenver we go from having zero borrows
+    // to having a single borrow. When a borrow occurs, this gets included
+    // in the generated `BorroeError/`BorrowMutError`
+    #[cfg(feature = "debug_refcell")]
+    borrowed_at: Cell<Option<&'static crate::panic::Location<'static>>>,
     value: UnsafeCell<T>,
 }
 
@@ -582,12 +588,19 @@
 #[stable(feature = "try_borrow", since = "1.13.0")]
 pub struct BorrowError {
     _private: (),
+    #[cfg(feature = "debug_refcell")]
+    location: &'static crate::panic::Location<'static>,
 }
 
 #[stable(feature = "try_borrow", since = "1.13.0")]
 impl Debug for BorrowError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("BorrowError").finish()
+        let mut builder = f.debug_struct("BorrowError");
+
+        #[cfg(feature = "debug_refcell")]
+        builder.field("location", self.location);
+
+        builder.finish()
     }
 }
 
@@ -602,12 +615,19 @@
 #[stable(feature = "try_borrow", since = "1.13.0")]
 pub struct BorrowMutError {
     _private: (),
+    #[cfg(feature = "debug_refcell")]
+    location: &'static crate::panic::Location<'static>,
 }
 
 #[stable(feature = "try_borrow", since = "1.13.0")]
 impl Debug for BorrowMutError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("BorrowMutError").finish()
+        let mut builder = f.debug_struct("BorrowMutError");
+
+        #[cfg(feature = "debug_refcell")]
+        builder.field("location", self.location);
+
+        builder.finish()
     }
 }
 
@@ -655,10 +675,15 @@
     /// let c = RefCell::new(5);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_refcell_new", since = "1.32.0")]
+    #[rustc_const_stable(feature = "const_refcell_new", since = "1.24.0")]
     #[inline]
     pub const fn new(value: T) -> RefCell<T> {
-        RefCell { value: UnsafeCell::new(value), borrow: Cell::new(UNUSED) }
+        RefCell {
+            value: UnsafeCell::new(value),
+            borrow: Cell::new(UNUSED),
+            #[cfg(feature = "debug_refcell")]
+            borrowed_at: Cell::new(None),
+        }
     }
 
     /// Consumes the `RefCell`, returning the wrapped value.
@@ -823,12 +848,29 @@
     /// ```
     #[stable(feature = "try_borrow", since = "1.13.0")]
     #[inline]
+    #[cfg_attr(feature = "debug_refcell", track_caller)]
     pub fn try_borrow(&self) -> Result<Ref<'_, T>, BorrowError> {
         match BorrowRef::new(&self.borrow) {
-            // SAFETY: `BorrowRef` ensures that there is only immutable access
-            // to the value while borrowed.
-            Some(b) => Ok(Ref { value: unsafe { &*self.value.get() }, borrow: b }),
-            None => Err(BorrowError { _private: () }),
+            Some(b) => {
+                #[cfg(feature = "debug_refcell")]
+                {
+                    // `borrowed_at` is always the *first* active borrow
+                    if b.borrow.get() == 1 {
+                        self.borrowed_at.set(Some(crate::panic::Location::caller()));
+                    }
+                }
+
+                // SAFETY: `BorrowRef` ensures that there is only immutable access
+                // to the value while borrowed.
+                Ok(Ref { value: unsafe { &*self.value.get() }, borrow: b })
+            }
+            None => Err(BorrowError {
+                _private: (),
+                // If a borrow occured, then we must already have an outstanding borrow,
+                // so `borrowed_at` will be `Some`
+                #[cfg(feature = "debug_refcell")]
+                location: self.borrowed_at.get().unwrap(),
+            }),
         }
     }
 
@@ -896,11 +938,25 @@
     /// ```
     #[stable(feature = "try_borrow", since = "1.13.0")]
     #[inline]
+    #[cfg_attr(feature = "debug_refcell", track_caller)]
     pub fn try_borrow_mut(&self) -> Result<RefMut<'_, T>, BorrowMutError> {
         match BorrowRefMut::new(&self.borrow) {
-            // SAFETY: `BorrowRef` guarantees unique access.
-            Some(b) => Ok(RefMut { value: unsafe { &mut *self.value.get() }, borrow: b }),
-            None => Err(BorrowMutError { _private: () }),
+            Some(b) => {
+                #[cfg(feature = "debug_refcell")]
+                {
+                    self.borrowed_at.set(Some(crate::panic::Location::caller()));
+                }
+
+                // SAFETY: `BorrowRef` guarantees unique access.
+                Ok(RefMut { value: unsafe { &mut *self.value.get() }, borrow: b })
+            }
+            None => Err(BorrowMutError {
+                _private: (),
+                // If a borrow occured, then we must already have an outstanding borrow,
+                // so `borrowed_at` will be `Some`
+                #[cfg(feature = "debug_refcell")]
+                location: self.borrowed_at.get().unwrap(),
+            }),
         }
     }
 
@@ -1016,7 +1072,13 @@
             // and is thus guaranteed to be valid for the lifetime of `self`.
             Ok(unsafe { &*self.value.get() })
         } else {
-            Err(BorrowError { _private: () })
+            Err(BorrowError {
+                _private: (),
+                // If a borrow occured, then we must already have an outstanding borrow,
+                // so `borrowed_at` will be `Some`
+                #[cfg(feature = "debug_refcell")]
+                location: self.borrowed_at.get().unwrap(),
+            })
         }
     }
 }
@@ -1753,7 +1815,7 @@
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_unsafe_cell_new", since = "1.32.0")]
-    #[inline]
+    #[inline(always)]
     pub const fn new(value: T) -> UnsafeCell<T> {
         UnsafeCell { value }
     }
@@ -1769,7 +1831,7 @@
     ///
     /// let five = uc.into_inner();
     /// ```
-    #[inline]
+    #[inline(always)]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_cell_into_inner", issue = "78729")]
     pub const fn into_inner(self) -> T {
@@ -1794,7 +1856,7 @@
     ///
     /// let five = uc.get();
     /// ```
-    #[inline]
+    #[inline(always)]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_stable(feature = "const_unsafecell_get", since = "1.32.0")]
     pub const fn get(&self) -> *mut T {
@@ -1819,7 +1881,7 @@
     ///
     /// assert_eq!(*c.get_mut(), 6);
     /// ```
-    #[inline]
+    #[inline(always)]
     #[stable(feature = "unsafe_cell_get_mut", since = "1.50.0")]
     pub fn get_mut(&mut self) -> &mut T {
         &mut self.value
@@ -1852,7 +1914,7 @@
     ///
     /// assert_eq!(uc.into_inner(), 5);
     /// ```
-    #[inline]
+    #[inline(always)]
     #[unstable(feature = "unsafe_cell_raw_get", issue = "66358")]
     pub const fn raw_get(this: *const Self) -> *mut T {
         // We can just cast the pointer from `UnsafeCell<T>` to `T` because of

diff --git a/library/core/src/char/methods.rs b/library/core/src/char/methods.rs
index 87a3d37..dcab2cd 100644
--- a/library/core/src/char/methods.rs
+++ b/library/core/src/char/methods.rs

@@ -403,16 +403,20 @@
     }
 
     /// An extended version of `escape_debug` that optionally permits escaping
-    /// Extended Grapheme codepoints. This allows us to format characters like
-    /// nonspacing marks better when they're at the start of a string.
+    /// Extended Grapheme codepoints, single quotes, and double quotes. This
+    /// allows us to format characters like nonspacing marks better when they're
+    /// at the start of a string, and allows escaping single quotes in
+    /// characters, and double quotes in strings.
     #[inline]
-    pub(crate) fn escape_debug_ext(self, escape_grapheme_extended: bool) -> EscapeDebug {
+    pub(crate) fn escape_debug_ext(self, args: EscapeDebugExtArgs) -> EscapeDebug {
         let init_state = match self {
             '\t' => EscapeDefaultState::Backslash('t'),
             '\r' => EscapeDefaultState::Backslash('r'),
             '\n' => EscapeDefaultState::Backslash('n'),
-            '\\' | '\'' | '"' => EscapeDefaultState::Backslash(self),
-            _ if escape_grapheme_extended && self.is_grapheme_extended() => {
+            '\\' => EscapeDefaultState::Backslash(self),
+            '"' if args.escape_double_quote => EscapeDefaultState::Backslash(self),
+            '\'' if args.escape_single_quote => EscapeDefaultState::Backslash(self),
+            _ if args.escape_grapheme_extended && self.is_grapheme_extended() => {
                 EscapeDefaultState::Unicode(self.escape_unicode())
             }
             _ if is_printable(self) => EscapeDefaultState::Char(self),
@@ -458,7 +462,7 @@
     #[stable(feature = "char_escape_debug", since = "1.20.0")]
     #[inline]
     pub fn escape_debug(self) -> EscapeDebug {
-        self.escape_debug_ext(true)
+        self.escape_debug_ext(EscapeDebugExtArgs::ESCAPE_ALL)
     }
 
     /// Returns an iterator that yields the literal escape code of a character
@@ -1565,6 +1569,25 @@
     }
 }
 
+pub(crate) struct EscapeDebugExtArgs {
+    /// Escape Extended Grapheme codepoints?
+    pub(crate) escape_grapheme_extended: bool,
+
+    /// Escape single quotes?
+    pub(crate) escape_single_quote: bool,
+
+    /// Escape double quotes?
+    pub(crate) escape_double_quote: bool,
+}
+
+impl EscapeDebugExtArgs {
+    pub(crate) const ESCAPE_ALL: Self = Self {
+        escape_grapheme_extended: true,
+        escape_single_quote: true,
+        escape_double_quote: true,
+    };
+}
+
 #[inline]
 const fn len_utf8(code: u32) -> usize {
     if code < MAX_ONE_B {

diff --git a/library/core/src/char/mod.rs b/library/core/src/char/mod.rs
index 788fafa..25a7c1d 100644
--- a/library/core/src/char/mod.rs
+++ b/library/core/src/char/mod.rs

@@ -45,6 +45,8 @@
 use crate::fmt::{self, Write};
 use crate::iter::FusedIterator;
 
+pub(crate) use self::methods::EscapeDebugExtArgs;
+
 // UTF-8 ranges and tags for encoding characters
 const TAG_CONT: u8 = 0b1000_0000;
 const TAG_TWO_B: u8 = 0b1100_0000;

diff --git a/library/core/src/cmp.rs b/library/core/src/cmp.rs
index 5bab1fb..f8b16b6 100644
--- a/library/core/src/cmp.rs
+++ b/library/core/src/cmp.rs

@@ -274,6 +274,7 @@
     //
     // This should never be implemented by hand.
     #[doc(hidden)]
+    #[cfg_attr(not(bootstrap), no_coverage)] // rust-lang/rust#84605
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     fn assert_receiver_is_total_eq(&self) {}
@@ -282,7 +283,7 @@
 /// Derive macro generating an impl of the trait `Eq`.
 #[rustc_builtin_macro]
 #[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
-#[allow_internal_unstable(core_intrinsics, derive_eq, structural_match)]
+#[allow_internal_unstable(core_intrinsics, derive_eq, structural_match, no_coverage)]
 pub macro Eq($item:item) {
     /* compiler built-in */
 }
@@ -334,7 +335,6 @@
     /// # Examples
     ///
     /// ```
-    /// #![feature(ordering_helpers)]
     /// use std::cmp::Ordering;
     ///
     /// assert_eq!(Ordering::Less.is_eq(), false);
@@ -343,7 +343,8 @@
     /// ```
     #[inline]
     #[must_use]
-    #[unstable(feature = "ordering_helpers", issue = "79885")]
+    #[rustc_const_stable(feature = "ordering_helpers", since = "1.53.0")]
+    #[stable(feature = "ordering_helpers", since = "1.53.0")]
     pub const fn is_eq(self) -> bool {
         matches!(self, Equal)
     }
@@ -353,7 +354,6 @@
     /// # Examples
     ///
     /// ```
-    /// #![feature(ordering_helpers)]
     /// use std::cmp::Ordering;
     ///
     /// assert_eq!(Ordering::Less.is_ne(), true);
@@ -362,7 +362,8 @@
     /// ```
     #[inline]
     #[must_use]
-    #[unstable(feature = "ordering_helpers", issue = "79885")]
+    #[rustc_const_stable(feature = "ordering_helpers", since = "1.53.0")]
+    #[stable(feature = "ordering_helpers", since = "1.53.0")]
     pub const fn is_ne(self) -> bool {
         !matches!(self, Equal)
     }
@@ -372,7 +373,6 @@
     /// # Examples
     ///
     /// ```
-    /// #![feature(ordering_helpers)]
     /// use std::cmp::Ordering;
     ///
     /// assert_eq!(Ordering::Less.is_lt(), true);
@@ -381,7 +381,8 @@
     /// ```
     #[inline]
     #[must_use]
-    #[unstable(feature = "ordering_helpers", issue = "79885")]
+    #[rustc_const_stable(feature = "ordering_helpers", since = "1.53.0")]
+    #[stable(feature = "ordering_helpers", since = "1.53.0")]
     pub const fn is_lt(self) -> bool {
         matches!(self, Less)
     }
@@ -391,7 +392,6 @@
     /// # Examples
     ///
     /// ```
-    /// #![feature(ordering_helpers)]
     /// use std::cmp::Ordering;
     ///
     /// assert_eq!(Ordering::Less.is_gt(), false);
@@ -400,7 +400,8 @@
     /// ```
     #[inline]
     #[must_use]
-    #[unstable(feature = "ordering_helpers", issue = "79885")]
+    #[rustc_const_stable(feature = "ordering_helpers", since = "1.53.0")]
+    #[stable(feature = "ordering_helpers", since = "1.53.0")]
     pub const fn is_gt(self) -> bool {
         matches!(self, Greater)
     }
@@ -410,7 +411,6 @@
     /// # Examples
     ///
     /// ```
-    /// #![feature(ordering_helpers)]
     /// use std::cmp::Ordering;
     ///
     /// assert_eq!(Ordering::Less.is_le(), true);
@@ -419,7 +419,8 @@
     /// ```
     #[inline]
     #[must_use]
-    #[unstable(feature = "ordering_helpers", issue = "79885")]
+    #[rustc_const_stable(feature = "ordering_helpers", since = "1.53.0")]
+    #[stable(feature = "ordering_helpers", since = "1.53.0")]
     pub const fn is_le(self) -> bool {
         !matches!(self, Greater)
     }
@@ -429,7 +430,6 @@
     /// # Examples
     ///
     /// ```
-    /// #![feature(ordering_helpers)]
     /// use std::cmp::Ordering;
     ///
     /// assert_eq!(Ordering::Less.is_ge(), false);
@@ -438,7 +438,8 @@
     /// ```
     #[inline]
     #[must_use]
-    #[unstable(feature = "ordering_helpers", issue = "79885")]
+    #[rustc_const_stable(feature = "ordering_helpers", since = "1.53.0")]
+    #[stable(feature = "ordering_helpers", since = "1.53.0")]
     pub const fn is_ge(self) -> bool {
         !matches!(self, Less)
     }
@@ -981,7 +982,11 @@
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
     fn le(&self, other: &Rhs) -> bool {
-        matches!(self.partial_cmp(other), Some(Less | Equal))
+        // Pattern `Some(Less | Eq)` optimizes worse than negating `None | Some(Greater)`.
+        // FIXME: The root cause was fixed upstream in LLVM with:
+        // https://github.com/llvm/llvm-project/commit/9bad7de9a3fb844f1ca2965f35d0c2a3d1e11775
+        // Revert this workaround once support for LLVM 12 gets dropped.
+        !matches!(self.partial_cmp(other), None | Some(Greater))
     }
 
     /// This method tests greater than (for `self` and `other`) and is used by the `>` operator.
@@ -1058,8 +1063,6 @@
 /// # Examples
 ///
 /// ```
-/// #![feature(cmp_min_max_by)]
-///
 /// use std::cmp;
 ///
 /// assert_eq!(cmp::min_by(-2, 1, |x: &i32, y: &i32| x.abs().cmp(&y.abs())), 1);
@@ -1067,7 +1070,7 @@
 /// ```
 #[inline]
 #[must_use]
-#[unstable(feature = "cmp_min_max_by", issue = "64460")]
+#[stable(feature = "cmp_min_max_by", since = "1.53.0")]
 pub fn min_by<T, F: FnOnce(&T, &T) -> Ordering>(v1: T, v2: T, compare: F) -> T {
     match compare(&v1, &v2) {
         Ordering::Less | Ordering::Equal => v1,
@@ -1082,8 +1085,6 @@
 /// # Examples
 ///
 /// ```
-/// #![feature(cmp_min_max_by)]
-///
 /// use std::cmp;
 ///
 /// assert_eq!(cmp::min_by_key(-2, 1, |x: &i32| x.abs()), 1);
@@ -1091,7 +1092,7 @@
 /// ```
 #[inline]
 #[must_use]
-#[unstable(feature = "cmp_min_max_by", issue = "64460")]
+#[stable(feature = "cmp_min_max_by", since = "1.53.0")]
 pub fn min_by_key<T, F: FnMut(&T) -> K, K: Ord>(v1: T, v2: T, mut f: F) -> T {
     min_by(v1, v2, |v1, v2| f(v1).cmp(&f(v2)))
 }
@@ -1124,8 +1125,6 @@
 /// # Examples
 ///
 /// ```
-/// #![feature(cmp_min_max_by)]
-///
 /// use std::cmp;
 ///
 /// assert_eq!(cmp::max_by(-2, 1, |x: &i32, y: &i32| x.abs().cmp(&y.abs())), -2);
@@ -1133,7 +1132,7 @@
 /// ```
 #[inline]
 #[must_use]
-#[unstable(feature = "cmp_min_max_by", issue = "64460")]
+#[stable(feature = "cmp_min_max_by", since = "1.53.0")]
 pub fn max_by<T, F: FnOnce(&T, &T) -> Ordering>(v1: T, v2: T, compare: F) -> T {
     match compare(&v1, &v2) {
         Ordering::Less | Ordering::Equal => v2,
@@ -1148,8 +1147,6 @@
 /// # Examples
 ///
 /// ```
-/// #![feature(cmp_min_max_by)]
-///
 /// use std::cmp;
 ///
 /// assert_eq!(cmp::max_by_key(-2, 1, |x: &i32| x.abs()), -2);
@@ -1157,7 +1154,7 @@
 /// ```
 #[inline]
 #[must_use]
-#[unstable(feature = "cmp_min_max_by", issue = "64460")]
+#[stable(feature = "cmp_min_max_by", since = "1.53.0")]
 pub fn max_by_key<T, F: FnMut(&T) -> K, K: Ord>(v1: T, v2: T, mut f: F) -> T {
     max_by(v1, v2, |v1, v2| f(v1).cmp(&f(v2)))
 }

diff --git a/library/core/src/convert/num.rs b/library/core/src/convert/num.rs
index 5b11361..a522b7d 100644
--- a/library/core/src/convert/num.rs
+++ b/library/core/src/convert/num.rs

@@ -45,8 +45,10 @@
 macro_rules! impl_from {
     ($Small: ty, $Large: ty, #[$attr:meta], $doc: expr) => {
         #[$attr]
-        #[doc = $doc]
         impl From<$Small> for $Large {
+            // Rustdocs on the impl block show a "[+] show undocumented items" toggle.
+            // Rustdocs on functions do not.
+            #[doc = $doc]
             #[inline]
             fn from(small: $Small) -> Self {
                 small as Self
@@ -383,8 +385,10 @@
 macro_rules! nzint_impl_from {
     ($Small: ty, $Large: ty, #[$attr:meta], $doc: expr) => {
         #[$attr]
-        #[doc = $doc]
         impl From<$Small> for $Large {
+            // Rustdocs on the impl block show a "[+] show undocumented items" toggle.
+            // Rustdocs on functions do not.
+            #[doc = $doc]
             #[inline]
             fn from(small: $Small) -> Self {
                 // SAFETY: input type guarantees the value is non-zero
@@ -450,10 +454,12 @@
 macro_rules! nzint_impl_try_from_int {
     ($Int: ty, $NonZeroInt: ty, #[$attr:meta], $doc: expr) => {
         #[$attr]
-        #[doc = $doc]
         impl TryFrom<$Int> for $NonZeroInt {
             type Error = TryFromIntError;
 
+            // Rustdocs on the impl block show a "[+] show undocumented items" toggle.
+            // Rustdocs on functions do not.
+            #[doc = $doc]
             #[inline]
             fn try_from(value: $Int) -> Result<Self, Self::Error> {
                 Self::new(value).ok_or(TryFromIntError(()))
@@ -489,10 +495,12 @@
 macro_rules! nzint_impl_try_from_nzint {
     ($From:ty => $To:ty, $doc: expr) => {
         #[stable(feature = "nzint_try_from_nzint_conv", since = "1.49.0")]
-        #[doc = $doc]
         impl TryFrom<$From> for $To {
             type Error = TryFromIntError;
 
+            // Rustdocs on the impl block show a "[+] show undocumented items" toggle.
+            // Rustdocs on functions do not.
+            #[doc = $doc]
             #[inline]
             fn try_from(value: $From) -> Result<Self, Self::Error> {
                 TryFrom::try_from(value.get()).map(|v| {

diff --git a/library/core/src/ffi.rs b/library/core/src/ffi.rs
index 9302baa..b208ddd 100644
--- a/library/core/src/ffi.rs
+++ b/library/core/src/ffi.rs

@@ -53,7 +53,7 @@
 #[stable(feature = "std_debug", since = "1.16.0")]
 impl fmt::Debug for c_void {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.pad("c_void")
+        f.debug_struct("c_void").finish()
     }
 }
 

diff --git a/library/core/src/fmt/builders.rs b/library/core/src/fmt/builders.rs
index d95d43f..b660788 100644
--- a/library/core/src/fmt/builders.rs
+++ b/library/core/src/fmt/builders.rs

@@ -165,7 +165,6 @@
     /// # Examples
     ///
     /// ```
-    /// # #![feature(debug_non_exhaustive)]
     /// use std::fmt;
     ///
     /// struct Bar {
@@ -186,31 +185,22 @@
     ///     "Bar { bar: 10, .. }",
     /// );
     /// ```
-    #[unstable(feature = "debug_non_exhaustive", issue = "67364")]
+    #[stable(feature = "debug_non_exhaustive", since = "1.53.0")]
     pub fn finish_non_exhaustive(&mut self) -> fmt::Result {
         self.result = self.result.and_then(|_| {
-            // Draw non-exhaustive dots (`..`), and open brace if necessary (no fields).
-            if self.is_pretty() {
-                if !self.has_fields {
-                    self.fmt.write_str(" {\n")?;
-                }
-                let mut slot = None;
-                let mut state = Default::default();
-                let mut writer = PadAdapter::wrap(&mut self.fmt, &mut slot, &mut state);
-                writer.write_str("..\n")?;
-            } else {
-                if self.has_fields {
-                    self.fmt.write_str(", ..")?;
+            if self.has_fields {
+                if self.is_pretty() {
+                    let mut slot = None;
+                    let mut state = Default::default();
+                    let mut writer = PadAdapter::wrap(&mut self.fmt, &mut slot, &mut state);
+                    writer.write_str("..\n")?;
+                    self.fmt.write_str("}")
                 } else {
-                    self.fmt.write_str(" { ..")?;
+                    self.fmt.write_str(", .. }")
                 }
-            }
-            if self.is_pretty() {
-                self.fmt.write_str("}")?
             } else {
-                self.fmt.write_str(" }")?;
+                self.fmt.write_str(" { .. }")
             }
-            Ok(())
         });
         self.result
     }

diff --git a/library/core/src/fmt/float.rs b/library/core/src/fmt/float.rs
index 5908da4..ece3cde 100644
--- a/library/core/src/fmt/float.rs
+++ b/library/core/src/fmt/float.rs

@@ -54,21 +54,14 @@
 }
 
 // Common code of floating point Debug and Display.
-fn float_to_decimal_common<T>(
-    fmt: &mut Formatter<'_>,
-    num: &T,
-    negative_zero: bool,
-    min_precision: usize,
-) -> Result
+fn float_to_decimal_common<T>(fmt: &mut Formatter<'_>, num: &T, min_precision: usize) -> Result
 where
     T: flt2dec::DecodableFloat,
 {
     let force_sign = fmt.sign_plus();
-    let sign = match (force_sign, negative_zero) {
-        (false, false) => flt2dec::Sign::Minus,
-        (false, true) => flt2dec::Sign::MinusRaw,
-        (true, false) => flt2dec::Sign::MinusPlus,
-        (true, true) => flt2dec::Sign::MinusPlusRaw,
+    let sign = match force_sign {
+        false => flt2dec::Sign::Minus,
+        true => flt2dec::Sign::MinusPlus,
     };
 
     if let Some(precision) = fmt.precision {
@@ -156,14 +149,14 @@
         #[stable(feature = "rust1", since = "1.0.0")]
         impl Debug for $ty {
             fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
-                float_to_decimal_common(fmt, self, true, 1)
+                float_to_decimal_common(fmt, self, 1)
             }
         }
 
         #[stable(feature = "rust1", since = "1.0.0")]
         impl Display for $ty {
             fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
-                float_to_decimal_common(fmt, self, false, 0)
+                float_to_decimal_common(fmt, self, 0)
             }
         }
 

diff --git a/library/core/src/fmt/mod.rs b/library/core/src/fmt/mod.rs
index 2df5e56..87042d9 100644
--- a/library/core/src/fmt/mod.rs
+++ b/library/core/src/fmt/mod.rs

@@ -3,6 +3,8 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use crate::cell::{Cell, Ref, RefCell, RefMut, UnsafeCell};
+use crate::char::EscapeDebugExtArgs;
+use crate::iter;
 use crate::marker::PhantomData;
 use crate::mem;
 use crate::num::flt2dec;
@@ -1087,7 +1089,7 @@
     match args.fmt {
         None => {
             // We can use default formatting parameters for all arguments.
-            for (arg, piece) in args.args.iter().zip(args.pieces.iter()) {
+            for (arg, piece) in iter::zip(args.args, args.pieces) {
                 formatter.buf.write_str(*piece)?;
                 (arg.formatter)(arg.value, &mut formatter)?;
                 idx += 1;
@@ -1096,7 +1098,7 @@
         Some(fmt) => {
             // Every spec has a corresponding argument that is preceded by
             // a string piece.
-            for (arg, piece) in fmt.iter().zip(args.pieces.iter()) {
+            for (arg, piece) in iter::zip(fmt, args.pieces) {
                 formatter.buf.write_str(*piece)?;
                 // SAFETY: arg and args.args come from the same Arguments,
                 // which guarantees the indexes are always within bounds.
@@ -2054,7 +2056,11 @@
         f.write_char('"')?;
         let mut from = 0;
         for (i, c) in self.char_indices() {
-            let esc = c.escape_debug();
+            let esc = c.escape_debug_ext(EscapeDebugExtArgs {
+                escape_grapheme_extended: true,
+                escape_single_quote: false,
+                escape_double_quote: true,
+            });
             // If char needs escaping, flush backlog so far and write, else skip
             if esc.len() != 1 {
                 f.write_str(&self[from..i])?;
@@ -2080,7 +2086,11 @@
 impl Debug for char {
     fn fmt(&self, f: &mut Formatter<'_>) -> Result {
         f.write_char('\'')?;
-        for c in self.escape_debug() {
+        for c in self.escape_debug_ext(EscapeDebugExtArgs {
+            escape_grapheme_extended: true,
+            escape_single_quote: true,
+            escape_double_quote: false,
+        }) {
             f.write_char(c)?
         }
         f.write_char('\'')
@@ -2210,7 +2220,7 @@
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> Debug for PhantomData<T> {
     fn fmt(&self, f: &mut Formatter<'_>) -> Result {
-        f.pad("PhantomData")
+        f.debug_struct("PhantomData").finish()
     }
 }
 
@@ -2258,9 +2268,9 @@
 }
 
 #[stable(feature = "core_impl_debug", since = "1.9.0")]
-impl<T: ?Sized + Debug> Debug for UnsafeCell<T> {
+impl<T: ?Sized> Debug for UnsafeCell<T> {
     fn fmt(&self, f: &mut Formatter<'_>) -> Result {
-        f.pad("UnsafeCell")
+        f.debug_struct("UnsafeCell").finish_non_exhaustive()
     }
 }
 

diff --git a/library/core/src/future/future.rs b/library/core/src/future/future.rs
index e9a99dd..cc4cf54 100644
--- a/library/core/src/future/future.rs
+++ b/library/core/src/future/future.rs

@@ -24,7 +24,8 @@
 /// `.await` the value.
 ///
 /// [`Waker`]: crate::task::Waker
-#[doc(spotlight)]
+#[cfg_attr(bootstrap, doc(spotlight))]
+#[cfg_attr(not(bootstrap), doc(notable_trait))]
 #[must_use = "futures do nothing unless you `.await` or poll them"]
 #[stable(feature = "futures_api", since = "1.36.0")]
 #[lang = "future_trait"]

diff --git a/library/core/src/hash/mod.rs b/library/core/src/hash/mod.rs
index 7bfa58d..77d3a35 100644
--- a/library/core/src/hash/mod.rs
+++ b/library/core/src/hash/mod.rs

@@ -175,6 +175,21 @@
 
     /// Feeds a slice of this type into the given [`Hasher`].
     ///
+    /// This method is meant as a convenience, but its implementation is
+    /// also explicitly left unspecified. It isn't guaranteed to be
+    /// equivalent to repeated calls of [`hash`] and implementations of
+    /// [`Hash`] should keep that in mind and call [`hash`] themselves
+    /// if the slice isn't treated as a whole unit in the [`PartialEq`]
+    /// implementation.
+    ///
+    /// For example, a [`VecDeque`] implementation might naïvely call
+    /// [`as_slices`] and then [`hash_slice`] on each slice, but this
+    /// is wrong since the two slices can change with a call to
+    /// [`make_contiguous`] without affecting the [`PartialEq`]
+    /// result. Since these slices aren't treated as singular
+    /// units, and instead part of a larger deque, this method cannot
+    /// be used.
+    ///
     /// # Examples
     ///
     /// ```
@@ -186,6 +201,12 @@
     /// Hash::hash_slice(&numbers, &mut hasher);
     /// println!("Hash is {:x}!", hasher.finish());
     /// ```
+    ///
+    /// [`VecDeque`]: ../../std/collections/struct.VecDeque.html
+    /// [`as_slices`]: ../../std/collections/struct.VecDeque.html#method.as_slices
+    /// [`make_contiguous`]: ../../std/collections/struct.VecDeque.html#method.make_contiguous
+    /// [`hash`]: Hash::hash
+    /// [`hash_slice`]: Hash::hash_slice
     #[stable(feature = "hash_slice", since = "1.3.0")]
     fn hash_slice<H: Hasher>(data: &[Self], state: &mut H)
     where
@@ -221,6 +242,11 @@
 /// instance (with [`write`] and [`write_u8`] etc.). Most of the time, `Hasher`
 /// instances are used in conjunction with the [`Hash`] trait.
 ///
+/// This trait makes no assumptions about how the various `write_*` methods are
+/// defined and implementations of [`Hash`] should not assume that they work one
+/// way or another. You cannot assume, for example, that a [`write_u32`] call is
+/// equivalent to four calls of [`write_u8`].
+///
 /// # Examples
 ///
 /// ```
@@ -240,6 +266,7 @@
 /// [`finish`]: Hasher::finish
 /// [`write`]: Hasher::write
 /// [`write_u8`]: Hasher::write_u8
+/// [`write_u32`]: Hasher::write_u32
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait Hasher {
     /// Returns the hash value for the values written so far.
@@ -507,7 +534,7 @@
 #[stable(since = "1.9.0", feature = "core_impl_debug")]
 impl<H> fmt::Debug for BuildHasherDefault<H> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.pad("BuildHasherDefault")
+        f.debug_struct("BuildHasherDefault").finish()
     }
 }
 
@@ -691,29 +718,9 @@
     impl<T: ?Sized> Hash for *const T {
         #[inline]
         fn hash<H: Hasher>(&self, state: &mut H) {
-            #[cfg(not(bootstrap))]
-            {
-                let (address, metadata) = self.to_raw_parts();
-                state.write_usize(address as usize);
-                metadata.hash(state);
-            }
-            #[cfg(bootstrap)]
-            {
-                if mem::size_of::<Self>() == mem::size_of::<usize>() {
-                    // Thin pointer
-                    state.write_usize(*self as *const () as usize);
-                } else {
-                    // Fat pointer
-                    // SAFETY: we are accessing the memory occupied by `self`
-                    // which is guaranteed to be valid.
-                    // This assumes a fat pointer can be represented by a `(usize, usize)`,
-                    // which is safe to do in `std` because it is shipped and kept in sync
-                    // with the implementation of fat pointers in `rustc`.
-                    let (a, b) = unsafe { *(self as *const Self as *const (usize, usize)) };
-                    state.write_usize(a);
-                    state.write_usize(b);
-                }
-            }
+            let (address, metadata) = self.to_raw_parts();
+            state.write_usize(address as usize);
+            metadata.hash(state);
         }
     }
 
@@ -721,29 +728,9 @@
     impl<T: ?Sized> Hash for *mut T {
         #[inline]
         fn hash<H: Hasher>(&self, state: &mut H) {
-            #[cfg(not(bootstrap))]
-            {
-                let (address, metadata) = self.to_raw_parts();
-                state.write_usize(address as usize);
-                metadata.hash(state);
-            }
-            #[cfg(bootstrap)]
-            {
-                if mem::size_of::<Self>() == mem::size_of::<usize>() {
-                    // Thin pointer
-                    state.write_usize(*self as *const () as usize);
-                } else {
-                    // Fat pointer
-                    // SAFETY: we are accessing the memory occupied by `self`
-                    // which is guaranteed to be valid.
-                    // This assumes a fat pointer can be represented by a `(usize, usize)`,
-                    // which is safe to do in `std` because it is shipped and kept in sync
-                    // with the implementation of fat pointers in `rustc`.
-                    let (a, b) = unsafe { *(self as *const Self as *const (usize, usize)) };
-                    state.write_usize(a);
-                    state.write_usize(b);
-                }
-            }
+            let (address, metadata) = self.to_raw_parts();
+            state.write_usize(address as usize);
+            metadata.hash(state);
         }
     }
 }

diff --git a/library/core/src/hint.rs b/library/core/src/hint.rs
index 3137295..f7aec73 100644
--- a/library/core/src/hint.rs
+++ b/library/core/src/hint.rs

@@ -154,7 +154,7 @@
 /// [`std::convert::identity`]: crate::convert::identity
 #[cfg_attr(not(miri), inline)]
 #[cfg_attr(miri, inline(never))]
-#[unstable(feature = "test", issue = "50297")]
+#[unstable(feature = "bench_black_box", issue = "64102")]
 #[cfg_attr(miri, allow(unused_mut))]
 pub fn black_box<T>(mut dummy: T) -> T {
     // We need to "use" the argument in some way LLVM can't introspect, and on

diff --git a/library/core/src/intrinsics.rs b/library/core/src/intrinsics.rs
index 073210c..175fc2e 100644
--- a/library/core/src/intrinsics.rs
+++ b/library/core/src/intrinsics.rs

@@ -1543,7 +1543,7 @@
     /// let num_trailing = unsafe { cttz_nonzero(x) };
     /// assert_eq!(num_trailing, 3);
     /// ```
-    #[rustc_const_unstable(feature = "const_cttz", issue = "none")]
+    #[rustc_const_stable(feature = "const_cttz", since = "1.53.0")]
     pub fn cttz_nonzero<T: Copy>(x: T) -> T;
 
     /// Reverses the bytes in an integer type `T`.
@@ -1843,7 +1843,7 @@
 pub const unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize) {
     extern "rust-intrinsic" {
         #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
-        fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize);
+        pub fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize);
     }
 
     // FIXME: Perform these checks only at run time

diff --git a/library/core/src/iter/adapters/mod.rs b/library/core/src/iter/adapters/mod.rs
index 41a7b13..61d8351 100644
--- a/library/core/src/iter/adapters/mod.rs
+++ b/library/core/src/iter/adapters/mod.rs

@@ -51,6 +51,9 @@
 #[unstable(feature = "trusted_random_access", issue = "none")]
 pub use self::zip::TrustedRandomAccess;
 
+#[unstable(feature = "iter_zip", issue = "83574")]
+pub use self::zip::zip;
+
 /// This trait provides transitive access to source-stage in an interator-adapter pipeline
 /// under the conditions that
 /// * the iterator source `S` itself implements `SourceIter<Source = S>`
@@ -191,3 +194,26 @@
         self.try_fold(init, ok(fold)).unwrap()
     }
 }
+
+#[unstable(issue = "none", feature = "inplace_iteration")]
+unsafe impl<S: Iterator, I, E> SourceIter for ResultShunt<'_, I, E>
+where
+    I: SourceIter<Source = S>,
+{
+    type Source = S;
+
+    #[inline]
+    unsafe fn as_inner(&mut self) -> &mut S {
+        // SAFETY: unsafe function forwarding to unsafe function with the same requirements
+        unsafe { SourceIter::as_inner(&mut self.iter) }
+    }
+}
+
+// SAFETY: ResultShunt::next calls I::find, which has to advance `iter` in order to
+// return `Some(_)`. Since `iter` has type `I: InPlaceIterable` it's guaranteed that
+// at least one item will be moved out from the underlying source.
+#[unstable(issue = "none", feature = "inplace_iteration")]
+unsafe impl<I, T, E> InPlaceIterable for ResultShunt<'_, I, E> where
+    I: Iterator<Item = Result<T, E>> + InPlaceIterable
+{
+}

diff --git a/library/core/src/iter/adapters/peekable.rs b/library/core/src/iter/adapters/peekable.rs
index 4330144..0d860ae 100644
--- a/library/core/src/iter/adapters/peekable.rs
+++ b/library/core/src/iter/adapters/peekable.rs

@@ -1,4 +1,4 @@
-use crate::iter::{adapters::SourceIter, FusedIterator, InPlaceIterable, TrustedLen};
+use crate::iter::{adapters::SourceIter, FusedIterator, TrustedLen};
 use crate::ops::Try;
 
 /// An iterator with a `peek()` that returns an optional reference to the next
@@ -233,7 +233,6 @@
     /// Basic usage:
     ///
     /// ```
-    /// #![feature(peekable_peek_mut)]
     /// let mut iter = [1, 2, 3].iter().peekable();
     ///
     /// // Like with `peek()`, we can see into the future without advancing the iterator.
@@ -251,7 +250,7 @@
     /// assert_eq!(iter.collect::<Vec<_>>(), vec![&5, &3]);
     /// ```
     #[inline]
-    #[unstable(feature = "peekable_peek_mut", issue = "78302")]
+    #[stable(feature = "peekable_peek_mut", since = "1.53.0")]
     pub fn peek_mut(&mut self) -> Option<&mut I::Item> {
         let iter = &mut self.iter;
         self.peeked.get_or_insert_with(|| iter.next()).as_mut()
@@ -334,6 +333,3 @@
         unsafe { SourceIter::as_inner(&mut self.iter) }
     }
 }
-
-#[unstable(issue = "none", feature = "inplace_iteration")]
-unsafe impl<I: InPlaceIterable> InPlaceIterable for Peekable<I> {}

diff --git a/library/core/src/iter/adapters/zip.rs b/library/core/src/iter/adapters/zip.rs
index ea7a809..2f8f504 100644
--- a/library/core/src/iter/adapters/zip.rs
+++ b/library/core/src/iter/adapters/zip.rs

@@ -5,8 +5,8 @@
 
 /// An iterator that iterates two other iterators simultaneously.
 ///
-/// This `struct` is created by [`Iterator::zip`]. See its documentation
-/// for more.
+/// This `struct` is created by [`zip`] or [`Iterator::zip`].
+/// See their documentation for more.
 #[derive(Clone)]
 #[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -33,6 +33,37 @@
     }
 }
 
+/// Converts the arguments to iterators and zips them.
+///
+/// See the documentation of [`Iterator::zip`] for more.
+///
+/// # Examples
+///
+/// ```
+/// #![feature(iter_zip)]
+/// use std::iter::zip;
+///
+/// let xs = [1, 2, 3];
+/// let ys = [4, 5, 6];
+/// for (x, y) in zip(&xs, &ys) {
+///     println!("x:{}, y:{}", x, y);
+/// }
+///
+/// // Nested zips are also possible:
+/// let zs = [7, 8, 9];
+/// for ((x, y), z) in zip(zip(&xs, &ys), &zs) {
+///     println!("x:{}, y:{}, z:{}", x, y, z);
+/// }
+/// ```
+#[unstable(feature = "iter_zip", issue = "83574")]
+pub fn zip<A, B>(a: A, b: B) -> Zip<A::IntoIter, B::IntoIter>
+where
+    A: IntoIterator,
+    B: IntoIterator,
+{
+    ZipImpl::new(a.into_iter(), b.into_iter())
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<A, B> Iterator for Zip<A, B>
 where

diff --git a/library/core/src/iter/mod.rs b/library/core/src/iter/mod.rs
index c57ba2b..2a179f0 100644
--- a/library/core/src/iter/mod.rs
+++ b/library/core/src/iter/mod.rs

@@ -389,6 +389,8 @@
     DoubleEndedIterator, ExactSizeIterator, Extend, FromIterator, IntoIterator, Product, Sum,
 };
 
+#[unstable(feature = "iter_zip", issue = "83574")]
+pub use self::adapters::zip;
 #[stable(feature = "iter_cloned", since = "1.1.0")]
 pub use self::adapters::Cloned;
 #[stable(feature = "iter_copied", since = "1.36.0")]

diff --git a/library/core/src/iter/range.rs b/library/core/src/iter/range.rs
index cc80e06..4b293c5 100644
--- a/library/core/src/iter/range.rs
+++ b/library/core/src/iter/range.rs

@@ -3,7 +3,7 @@
 use crate::mem;
 use crate::ops::{self, Try};
 
-use super::{FusedIterator, TrustedLen};
+use super::{FusedIterator, TrustedLen, TrustedRandomAccess};
 
 /// Objects that have a notion of *successor* and *predecessor* operations.
 ///
@@ -493,6 +493,18 @@
     )*)
 }
 
+/// Safety: This macro must only be used on types that are `Copy` and result in ranges
+/// which have an exact `size_hint()` where the upper bound must not be `None`.
+macro_rules! unsafe_range_trusted_random_access_impl {
+    ($($t:ty)*) => ($(
+        #[doc(hidden)]
+        #[unstable(feature = "trusted_random_access", issue = "none")]
+        unsafe impl TrustedRandomAccess for ops::Range<$t> {
+            const MAY_HAVE_SIDE_EFFECT: bool = false;
+        }
+    )*)
+}
+
 macro_rules! range_incl_exact_iter_impl {
     ($($t:ty)*) => ($(
         #[stable(feature = "inclusive_range", since = "1.26.0")]
@@ -553,6 +565,18 @@
     fn max(mut self) -> Option<A> {
         self.next_back()
     }
+
+    #[inline]
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item
+    where
+        Self: TrustedRandomAccess,
+    {
+        // SAFETY: The TrustedRandomAccess contract requires that callers only  pass an index
+        // that is in bounds.
+        // Additionally Self: TrustedRandomAccess is only implemented for Copy types
+        // which means even repeated reads of the same index would be safe.
+        unsafe { Step::forward_unchecked(self.start.clone(), idx) }
+    }
 }
 
 // These macros generate `ExactSizeIterator` impls for various range types.
@@ -574,6 +598,23 @@
     u32
     i32
 }
+
+unsafe_range_trusted_random_access_impl! {
+    usize u8 u16
+    isize i8 i16
+}
+
+#[cfg(target_pointer_width = "32")]
+unsafe_range_trusted_random_access_impl! {
+    u32 i32
+}
+
+#[cfg(target_pointer_width = "64")]
+unsafe_range_trusted_random_access_impl! {
+    u32 i32
+    u64 i64
+}
+
 range_incl_exact_iter_impl! {
     u8
     i8

diff --git a/library/core/src/iter/sources/empty.rs b/library/core/src/iter/sources/empty.rs
index 5d4a9fe..919c564 100644
--- a/library/core/src/iter/sources/empty.rs
+++ b/library/core/src/iter/sources/empty.rs

@@ -36,7 +36,7 @@
 #[stable(feature = "core_impl_debug", since = "1.9.0")]
 impl<T> fmt::Debug for Empty<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.pad("Empty")
+        f.debug_struct("Empty").finish()
     }
 }
 

diff --git a/library/core/src/iter/traits/collect.rs b/library/core/src/iter/traits/collect.rs
index 1ae6d15..13a2e24 100644
--- a/library/core/src/iter/traits/collect.rs
+++ b/library/core/src/iter/traits/collect.rs

@@ -198,6 +198,7 @@
 /// }
 /// ```
 #[rustc_diagnostic_item = "IntoIterator"]
+#[cfg_attr(not(bootstrap), rustc_skip_array_during_method_dispatch)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait IntoIterator {
     /// The type of the elements being iterated over.

diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs
index a07750f..da9e5fd 100644
--- a/library/core/src/iter/traits/iterator.rs
+++ b/library/core/src/iter/traits/iterator.rs

@@ -81,8 +81,8 @@
     ),
     on(
         _Self = "[]",
-        label = "borrow the array with `&` or call `.iter()` on it to iterate over it",
-        note = "arrays are not iterators, but slices like the following are: `&[1, 2, 3]`"
+        label = "arrays do not yet implement `IntoIterator`; try using `std::array::IntoIter::new(arr)`",
+        note = "see <https://github.com/rust-lang/rust/pull/65819> for more details"
     ),
     on(
         _Self = "{integral}",
@@ -92,7 +92,8 @@
     label = "`{Self}` is not an iterator",
     message = "`{Self}` is not an iterator"
 )]
-#[doc(spotlight)]
+#[cfg_attr(bootstrap, doc(spotlight))]
+#[cfg_attr(not(bootstrap), doc(notable_trait))]
 #[rustc_diagnostic_item = "Iterator"]
 #[must_use = "iterators are lazy and do nothing unless consumed"]
 pub trait Iterator {
@@ -936,20 +937,16 @@
         Enumerate::new(self)
     }
 
-    /// Creates an iterator which can use [`peek`] to look at the next element of
-    /// the iterator without consuming it.
+    /// Creates an iterator which can use the [`peek`] and [`peek_mut`] methods
+    /// to look at the next element of the iterator without consuming it. See
+    /// their documentation for more information.
     ///
-    /// Adds a [`peek`] method to an iterator. See its documentation for
-    /// more information.
+    /// Note that the underlying iterator is still advanced when [`peek`] or
+    /// [`peek_mut`] are called for the first time: In order to retrieve the
+    /// next element, [`next`] is called on the underlying iterator, hence any
+    /// side effects (i.e. anything other than fetching the next value) of
+    /// the [`next`] method will occur.
     ///
-    /// Note that the underlying iterator is still advanced when [`peek`] is
-    /// called for the first time: In order to retrieve the next element,
-    /// [`next`] is called on the underlying iterator, hence any side effects (i.e.
-    /// anything other than fetching the next value) of the [`next`] method
-    /// will occur.
-    ///
-    /// [`peek`]: Peekable::peek
-    /// [`next`]: Iterator::next
     ///
     /// # Examples
     ///
@@ -976,6 +973,32 @@
     /// assert_eq!(iter.peek(), None);
     /// assert_eq!(iter.next(), None);
     /// ```
+    ///
+    /// Using [`peek_mut`] to mutate the next item without advancing the
+    /// iterator:
+    ///
+    /// ```
+    /// let xs = [1, 2, 3];
+    ///
+    /// let mut iter = xs.iter().peekable();
+    ///
+    /// // `peek_mut()` lets us see into the future
+    /// assert_eq!(iter.peek_mut(), Some(&mut &1));
+    /// assert_eq!(iter.peek_mut(), Some(&mut &1));
+    /// assert_eq!(iter.next(), Some(&1));
+    ///
+    /// if let Some(mut p) = iter.peek_mut() {
+    ///     assert_eq!(*p, &2);
+    ///     // put a value into the iterator
+    ///     *p = &1000;
+    /// }
+    ///
+    /// // The value reappears as the iterator continues
+    /// assert_eq!(iter.collect::<Vec<_>>(), vec![&1000, &3]);
+    /// ```
+    /// [`peek`]: Peekable::peek
+    /// [`peek_mut`]: Peekable::peek_mut
+    /// [`next`]: Iterator::next
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     fn peekable(self) -> Peekable<Self>
@@ -1228,7 +1251,11 @@
 
     /// Creates an iterator that skips the first `n` elements.
     ///
-    /// After they have been consumed, the rest of the elements are yielded.
+    /// `skip(n)` skips elements until `n` elements are skipped or the end of the
+    /// iterator is reached (whichever happens first). After that, all the remaining
+    /// elements are yielded. In particular, if the original iterator is too short,
+    /// then the returned iterator is empty.
+    ///
     /// Rather than overriding this method directly, instead override the `nth` method.
     ///
     /// # Examples
@@ -1252,7 +1279,14 @@
         Skip::new(self, n)
     }
 
-    /// Creates an iterator that yields its first `n` elements.
+    /// Creates an iterator that yields the first `n` elements, or fewer
+    /// if the underlying iterator ends sooner.
+    ///
+    /// `take(n)` yields elements until `n` elements are yielded or the end of
+    /// the iterator is reached (whichever happens first).
+    /// The returned iterator is a prefix of length `n` if the original iterator
+    /// contains at least `n` elements, otherwise it contains all of the
+    /// (fewer than `n`) elements of the original iterator.
     ///
     /// # Examples
     ///
@@ -1461,7 +1495,12 @@
     /// [`Some(T)`] again. `fuse()` adapts an iterator, ensuring that after a
     /// [`None`] is given, it will always return [`None`] forever.
     ///
+    /// Note that the [`Fuse`] wrapper is a no-op on iterators that implement
+    /// the [`FusedIterator`] trait. `fuse()` may therefore behave incorrectly
+    /// if the [`FusedIterator`] trait is improperly implemented.
+    ///
     /// [`Some(T)`]: Some
+    /// [`FusedIterator`]: crate::iter::FusedIterator
     ///
     /// # Examples
     ///
@@ -1612,31 +1651,16 @@
     /// Basic usage:
     ///
     /// ```
-    /// let a = [1, 2, 3];
+    /// let mut words = vec!["hello", "world", "of", "Rust"].into_iter();
     ///
-    /// let iter = a.iter();
+    /// // Take the first two words.
+    /// let hello_world: Vec<_> = words.by_ref().take(2).collect();
+    /// assert_eq!(hello_world, vec!["hello", "world"]);
     ///
-    /// let sum: i32 = iter.take(5).fold(0, |acc, i| acc + i);
-    ///
-    /// assert_eq!(sum, 6);
-    ///
-    /// // if we try to use iter again, it won't work. The following line
-    /// // gives "error: use of moved value: `iter`
-    /// // assert_eq!(iter.next(), None);
-    ///
-    /// // let's try that again
-    /// let a = [1, 2, 3];
-    ///
-    /// let mut iter = a.iter();
-    ///
-    /// // instead, we add in a .by_ref()
-    /// let sum: i32 = iter.by_ref().take(2).fold(0, |acc, i| acc + i);
-    ///
-    /// assert_eq!(sum, 3);
-    ///
-    /// // now this is just fine:
-    /// assert_eq!(iter.next(), Some(&3));
-    /// assert_eq!(iter.next(), None);
+    /// // Collect the rest of the words.
+    /// // We can only do this because we used `by_ref` earlier.
+    /// let of_rust: Vec<_> = words.collect();
+    /// assert_eq!(of_rust, vec!["of", "Rust"]);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     fn by_ref(&mut self) -> &mut Self
@@ -2109,7 +2133,6 @@
     /// ```
     ///
     /// [`reduce()`]: Iterator::reduce
-    #[doc(alias = "reduce")]
     #[doc(alias = "inject")]
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]

diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 8e35adc..d1329b8 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs

@@ -79,14 +79,14 @@
 #![feature(const_int_unchecked_arith)]
 #![feature(const_mut_refs)]
 #![feature(const_refs_to_cell)]
-#![feature(const_cttz)]
 #![feature(const_panic)]
 #![feature(const_pin)]
-#![feature(const_fn)]
+#![cfg_attr(bootstrap, feature(const_fn))]
 #![feature(const_fn_union)]
 #![feature(const_impl_trait)]
 #![feature(const_fn_floating_point_arithmetic)]
 #![feature(const_fn_fn_ptr_basics)]
+#![cfg_attr(not(bootstrap), feature(const_fn_trait_bound))]
 #![feature(const_option)]
 #![feature(const_precise_live_drops)]
 #![feature(const_ptr_offset)]
@@ -109,9 +109,9 @@
 #![feature(custom_inner_attributes)]
 #![feature(decl_macro)]
 #![feature(doc_cfg)]
-#![feature(doc_spotlight)]
+#![cfg_attr(bootstrap, feature(doc_spotlight))]
+#![cfg_attr(not(bootstrap), feature(doc_notable_trait))]
 #![feature(duration_consts_2)]
-#![feature(duration_saturating_ops)]
 #![feature(extended_key_value_attributes)]
 #![feature(extern_types)]
 #![feature(fundamental)]
@@ -126,9 +126,9 @@
 #![feature(exhaustive_patterns)]
 #![feature(no_core)]
 #![feature(auto_traits)]
-#![feature(or_patterns)]
+#![cfg_attr(bootstrap, feature(or_patterns))]
 #![feature(prelude_import)]
-#![cfg_attr(not(bootstrap), feature(ptr_metadata))]
+#![feature(ptr_metadata)]
 #![feature(repr_simd, platform_intrinsics)]
 #![feature(rustc_attrs)]
 #![feature(simd_ffi)]
@@ -138,6 +138,7 @@
 #![feature(stmt_expr_attributes)]
 #![feature(str_split_as_str)]
 #![feature(str_split_inclusive_as_str)]
+#![feature(char_indices_offset)]
 #![feature(trait_alias)]
 #![feature(transparent_unions)]
 #![feature(try_blocks)]
@@ -165,8 +166,8 @@
 #![feature(const_caller_location)]
 #![feature(slice_ptr_get)]
 #![feature(no_niche)] // rust-lang/rust#68303
+#![cfg_attr(not(bootstrap), feature(no_coverage))] // rust-lang/rust#84605
 #![feature(int_error_matching)]
-#![cfg_attr(bootstrap, feature(unsafe_block_in_unsafe_fn))]
 #![deny(unsafe_op_in_unsafe_fn)]
 
 #[prelude_import]
@@ -298,8 +299,8 @@
     unused_imports,
     unsafe_op_in_unsafe_fn
 )]
-#[cfg_attr(bootstrap, allow(non_autolinks))]
-#[cfg_attr(not(bootstrap), allow(rustdoc::non_autolinks))]
+#[cfg_attr(bootstrap, allow(rustdoc::non_autolinks))]
+#[cfg_attr(not(bootstrap), allow(rustdoc::bare_urls))]
 // FIXME: This annotation should be moved into rust-lang/stdarch after clashing_extern_declarations is
 // merged. It currently cannot because bootstrap fails as the lint hasn't been defined yet.
 #[allow(clashing_extern_declarations)]

diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs
index a0a8eec..66efa3c 100644
--- a/library/core/src/macros/mod.rs
+++ b/library/core/src/macros/mod.rs

@@ -1301,7 +1301,6 @@
     }
 
     /// Attribute macro used to apply derive macros.
-    #[cfg(not(bootstrap))]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_builtin_macro]
     pub macro derive($item:item) {
@@ -1363,7 +1362,6 @@
     }
 
     /// Expands all `#[cfg]` and `#[cfg_attr]` attributes in the code fragment it's applied to.
-    #[cfg(not(bootstrap))]
     #[unstable(
         feature = "cfg_eval",
         issue = "82679",

diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs
index 85e0e72..fb95734 100644
--- a/library/core/src/marker.rs
+++ b/library/core/src/marker.rs

@@ -765,7 +765,7 @@
 /// [`pin` module]: crate::pin
 #[stable(feature = "pin", since = "1.33.0")]
 #[rustc_on_unimplemented(
-    on(_Self = "std::future::Future", note = "consider using `Box::pin`",),
+    note = "consider using `Box::pin`",
     message = "`{Self}` cannot be unpinned"
 )]
 #[lang = "unpin"]

diff --git a/library/core/src/mem/maybe_uninit.rs b/library/core/src/mem/maybe_uninit.rs
index cb07293..4d7d475 100644
--- a/library/core/src/mem/maybe_uninit.rs
+++ b/library/core/src/mem/maybe_uninit.rs

@@ -190,6 +190,8 @@
 ///     let ptr = uninit.as_mut_ptr();
 ///
 ///     // Initializing the `name` field
+///     // Using `write` instead of assignment via `=` to not call `drop` on the
+///     // old, uninitialized value.
 ///     unsafe { addr_of_mut!((*ptr).name).write("Bob".to_string()); }
 ///
 ///     // Initializing the `list` field
@@ -319,9 +321,9 @@
     /// Create a new array of `MaybeUninit<T>` items, in an uninitialized state.
     ///
     /// Note: in a future Rust version this method may become unnecessary
-    /// when array literal syntax allows
-    /// [repeating const expressions](https://github.com/rust-lang/rust/issues/49147).
-    /// The example below could then use `let mut buf = [MaybeUninit::<u8>::uninit(); 32];`.
+    /// when Rust allows
+    /// [inline const expressions](https://github.com/rust-lang/rust/issues/76001).
+    /// The example below could then use `let mut buf = [const { MaybeUninit::<u8>::uninit() }; 32];`.
     ///
     /// # Examples
     ///
@@ -734,22 +736,22 @@
     /// #![feature(maybe_uninit_ref)]
     /// use std::mem::MaybeUninit;
     ///
-    /// # unsafe extern "C" fn initialize_buffer(buf: *mut [u8; 2048]) { *buf = [0; 2048] }
+    /// # unsafe extern "C" fn initialize_buffer(buf: *mut [u8; 1024]) { *buf = [0; 1024] }
     /// # #[cfg(FALSE)]
     /// extern "C" {
     ///     /// Initializes *all* the bytes of the input buffer.
-    ///     fn initialize_buffer(buf: *mut [u8; 2048]);
+    ///     fn initialize_buffer(buf: *mut [u8; 1024]);
     /// }
     ///
-    /// let mut buf = MaybeUninit::<[u8; 2048]>::uninit();
+    /// let mut buf = MaybeUninit::<[u8; 1024]>::uninit();
     ///
     /// // Initialize `buf`:
     /// unsafe { initialize_buffer(buf.as_mut_ptr()); }
     /// // Now we know that `buf` has been initialized, so we could `.assume_init()` it.
-    /// // However, using `.assume_init()` may trigger a `memcpy` of the 2048 bytes.
+    /// // However, using `.assume_init()` may trigger a `memcpy` of the 1024 bytes.
     /// // To assert our buffer has been initialized without copying it, we upgrade
-    /// // the `&mut MaybeUninit<[u8; 2048]>` to a `&mut [u8; 2048]`:
-    /// let buf: &mut [u8; 2048] = unsafe {
+    /// // the `&mut MaybeUninit<[u8; 1024]>` to a `&mut [u8; 1024]`:
+    /// let buf: &mut [u8; 1024] = unsafe {
     ///     // SAFETY: `buf` has been initialized.
     ///     buf.assume_init_mut()
     /// };

diff --git a/library/core/src/mem/mod.rs b/library/core/src/mem/mod.rs
index c4f0d91..c6750c5 100644
--- a/library/core/src/mem/mod.rs
+++ b/library/core/src/mem/mod.rs

@@ -297,7 +297,7 @@
 #[inline(always)]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_promotable]
-#[rustc_const_stable(feature = "const_size_of", since = "1.32.0")]
+#[rustc_const_stable(feature = "const_size_of", since = "1.24.0")]
 pub const fn size_of<T>() -> usize {
     intrinsics::size_of::<T>()
 }
@@ -440,7 +440,7 @@
 #[inline(always)]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_promotable]
-#[rustc_const_stable(feature = "const_align_of", since = "1.32.0")]
+#[rustc_const_stable(feature = "const_align_of", since = "1.24.0")]
 pub const fn align_of<T>() -> usize {
     intrinsics::min_align_of::<T>()
 }
@@ -884,7 +884,6 @@
 /// ```
 ///
 /// [`RefCell`]: crate::cell::RefCell
-#[doc(alias = "delete")]
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn drop<T>(_x: T) {}

diff --git a/library/core/src/num/bignum.rs b/library/core/src/num/bignum.rs
index 6a1a1e1..197b85f 100644
--- a/library/core/src/num/bignum.rs
+++ b/library/core/src/num/bignum.rs

@@ -181,11 +181,12 @@
             /// Adds `other` to itself and returns its own mutable reference.
             pub fn add<'a>(&'a mut self, other: &$name) -> &'a mut $name {
                 use crate::cmp;
+                use crate::iter;
                 use crate::num::bignum::FullOps;
 
                 let mut sz = cmp::max(self.size, other.size);
                 let mut carry = false;
-                for (a, b) in self.base[..sz].iter_mut().zip(&other.base[..sz]) {
+                for (a, b) in iter::zip(&mut self.base[..sz], &other.base[..sz]) {
                     let (c, v) = (*a).full_add(*b, carry);
                     *a = v;
                     carry = c;
@@ -219,11 +220,12 @@
             /// Subtracts `other` from itself and returns its own mutable reference.
             pub fn sub<'a>(&'a mut self, other: &$name) -> &'a mut $name {
                 use crate::cmp;
+                use crate::iter;
                 use crate::num::bignum::FullOps;
 
                 let sz = cmp::max(self.size, other.size);
                 let mut noborrow = true;
-                for (a, b) in self.base[..sz].iter_mut().zip(&other.base[..sz]) {
+                for (a, b) in iter::zip(&mut self.base[..sz], &other.base[..sz]) {
                     let (c, v) = (*a).full_add(!*b, noborrow);
                     *a = v;
                     noborrow = c;

diff --git a/library/core/src/num/dec2flt/algorithm.rs b/library/core/src/num/dec2flt/algorithm.rs
index a5fbdc6..313b687 100644
--- a/library/core/src/num/dec2flt/algorithm.rs
+++ b/library/core/src/num/dec2flt/algorithm.rs

@@ -62,10 +62,9 @@
         // any `u16`
         unsafe {
             asm!(
-                "fldcw ({})",
+                "fldcw word ptr [{}]",
                 in(reg) &cw,
-                // FIXME: We are using ATT syntax to support LLVM 8 and LLVM 9.
-                options(att_syntax, nostack),
+                options(nostack),
             )
         }
     }
@@ -87,10 +86,9 @@
         // any `u16`
         unsafe {
             asm!(
-                "fnstcw ({})",
+                "fnstcw word ptr [{}]",
                 in(reg) &mut cw,
-                // FIXME: We are using ATT syntax to support LLVM 8 and LLVM 9.
-                options(att_syntax, nostack),
+                options(nostack),
             )
         }
 

diff --git a/library/core/src/num/dec2flt/mod.rs b/library/core/src/num/dec2flt/mod.rs
index 20ac165..f008a64 100644
--- a/library/core/src/num/dec2flt/mod.rs
+++ b/library/core/src/num/dec2flt/mod.rs

@@ -239,13 +239,15 @@
         ParseResult::Valid(decimal) => convert(decimal)?,
         ParseResult::ShortcutToInf => T::INFINITY,
         ParseResult::ShortcutToZero => T::ZERO,
-        ParseResult::Invalid => match s {
-            "inf" => T::INFINITY,
-            "NaN" => T::NAN,
-            _ => {
+        ParseResult::Invalid => {
+            if s.eq_ignore_ascii_case("nan") {
+                T::NAN
+            } else if s.eq_ignore_ascii_case("inf") || s.eq_ignore_ascii_case("infinity") {
+                T::INFINITY
+            } else {
                 return Err(pfe_invalid());
             }
-        },
+        }
     };
 
     match sign {

diff --git a/library/core/src/num/f32.rs b/library/core/src/num/f32.rs
index 690247b..0d6d919 100644
--- a/library/core/src/num/f32.rs
+++ b/library/core/src/num/f32.rs

@@ -500,7 +500,6 @@
     /// Returns `true` if the number is [subnormal].
     ///
     /// ```
-    /// #![feature(is_subnormal)]
     /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
     /// let max = f32::MAX;
     /// let lower_than_min = 1.0e-40_f32;
@@ -516,7 +515,7 @@
     /// assert!(lower_than_min.is_subnormal());
     /// ```
     /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
-    #[unstable(feature = "is_subnormal", issue = "79288")]
+    #[stable(feature = "is_subnormal", since = "1.53.0")]
     #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")]
     #[inline]
     pub const fn is_subnormal(self) -> bool {

diff --git a/library/core/src/num/f64.rs b/library/core/src/num/f64.rs
index 6d37372..42214e7 100644
--- a/library/core/src/num/f64.rs
+++ b/library/core/src/num/f64.rs

@@ -499,7 +499,6 @@
     /// Returns `true` if the number is [subnormal].
     ///
     /// ```
-    /// #![feature(is_subnormal)]
     /// let min = f64::MIN_POSITIVE; // 2.2250738585072014e-308_f64
     /// let max = f64::MAX;
     /// let lower_than_min = 1.0e-308_f64;
@@ -515,7 +514,7 @@
     /// assert!(lower_than_min.is_subnormal());
     /// ```
     /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
-    #[unstable(feature = "is_subnormal", issue = "79288")]
+    #[stable(feature = "is_subnormal", since = "1.53.0")]
     #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")]
     #[inline]
     pub const fn is_subnormal(self) -> bool {

diff --git a/library/core/src/num/flt2dec/mod.rs b/library/core/src/num/flt2dec/mod.rs
index e8f9d65..93bdf50 100644
--- a/library/core/src/num/flt2dec/mod.rs
+++ b/library/core/src/num/flt2dec/mod.rs

@@ -399,14 +399,10 @@
 /// Sign formatting options.
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 pub enum Sign {
-    /// Prints `-` only for the negative non-zero values.
-    Minus, // -inf -1  0  0  1  inf nan
-    /// Prints `-` only for any negative values (including the negative zero).
-    MinusRaw, // -inf -1 -0  0  1  inf nan
-    /// Prints `-` for the negative non-zero values, or `+` otherwise.
-    MinusPlus, // -inf -1 +0 +0 +1 +inf nan
-    /// Prints `-` for any negative values (including the negative zero), or `+` otherwise.
-    MinusPlusRaw, // -inf -1 -0 +0 +1 +inf nan
+    /// Prints `-` for any negative value.
+    Minus, // -inf -1 -0  0  1  inf nan
+    /// Prints `-` for any negative value, or `+` otherwise.
+    MinusPlus, // -inf -1 -0 +0 +1 +inf nan
 }
 
 /// Returns the static byte string corresponding to the sign to be formatted.
@@ -414,30 +410,14 @@
 fn determine_sign(sign: Sign, decoded: &FullDecoded, negative: bool) -> &'static str {
     match (*decoded, sign) {
         (FullDecoded::Nan, _) => "",
-        (FullDecoded::Zero, Sign::Minus) => "",
-        (FullDecoded::Zero, Sign::MinusRaw) => {
+        (_, Sign::Minus) => {
             if negative {
                 "-"
             } else {
                 ""
             }
         }
-        (FullDecoded::Zero, Sign::MinusPlus) => "+",
-        (FullDecoded::Zero, Sign::MinusPlusRaw) => {
-            if negative {
-                "-"
-            } else {
-                "+"
-            }
-        }
-        (_, Sign::Minus | Sign::MinusRaw) => {
-            if negative {
-                "-"
-            } else {
-                ""
-            }
-        }
-        (_, Sign::MinusPlus | Sign::MinusPlusRaw) => {
+        (_, Sign::MinusPlus) => {
             if negative {
                 "-"
             } else {

diff --git a/library/core/src/num/int_macros.rs b/library/core/src/num/int_macros.rs
index ce9dca3..4b34113 100644
--- a/library/core/src/num/int_macros.rs
+++ b/library/core/src/num/int_macros.rs

@@ -32,10 +32,9 @@
         /// # Examples
         ///
         /// ```
-        /// #![feature(int_bits_const)]
         #[doc = concat!("assert_eq!(", stringify!($SelfT), "::BITS, ", stringify!($BITS), ");")]
         /// ```
-        #[unstable(feature = "int_bits_const", issue = "76904")]
+        #[stable(feature = "int_bits_const", since = "1.53.0")]
         pub const BITS: u32 = $BITS;
 
         /// Converts a string slice in a given base to an integer.
@@ -80,7 +79,7 @@
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
         #[doc(alias = "popcount")]
         #[doc(alias = "popcnt")]
-        #[inline]
+        #[inline(always)]
         pub const fn count_ones(self) -> u32 { (self as $UnsignedT).count_ones() }
 
         /// Returns the number of zeros in the binary representation of `self`.
@@ -94,7 +93,7 @@
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn count_zeros(self) -> u32 {
             (!self).count_ones()
         }
@@ -112,7 +111,7 @@
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn leading_zeros(self) -> u32 {
             (self as $UnsignedT).leading_zeros()
         }
@@ -130,7 +129,7 @@
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn trailing_zeros(self) -> u32 {
             (self as $UnsignedT).trailing_zeros()
         }
@@ -148,7 +147,7 @@
         /// ```
         #[stable(feature = "leading_trailing_ones", since = "1.46.0")]
         #[rustc_const_stable(feature = "leading_trailing_ones", since = "1.46.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn leading_ones(self) -> u32 {
             (self as $UnsignedT).leading_ones()
         }
@@ -166,7 +165,7 @@
         /// ```
         #[stable(feature = "leading_trailing_ones", since = "1.46.0")]
         #[rustc_const_stable(feature = "leading_trailing_ones", since = "1.46.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn trailing_ones(self) -> u32 {
             (self as $UnsignedT).trailing_ones()
         }
@@ -190,7 +189,7 @@
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn rotate_left(self, n: u32) -> Self {
             (self as $UnsignedT).rotate_left(n) as Self
         }
@@ -215,7 +214,7 @@
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn rotate_right(self, n: u32) -> Self {
             (self as $UnsignedT).rotate_right(n) as Self
         }
@@ -235,7 +234,7 @@
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn swap_bytes(self) -> Self {
             (self as $UnsignedT).swap_bytes() as Self
         }
@@ -255,8 +254,8 @@
         #[doc = concat!("assert_eq!(0, 0", stringify!($SelfT), ".reverse_bits());")]
         /// ```
         #[stable(feature = "reverse_bits", since = "1.37.0")]
-        #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
-        #[inline]
+        #[rustc_const_stable(feature = "const_int_methods", since = "1.37.0")]
+        #[inline(always)]
         #[must_use]
         pub const fn reverse_bits(self) -> Self {
             (self as $UnsignedT).reverse_bits() as Self
@@ -417,7 +416,7 @@
         )]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub unsafe fn unchecked_add(self, rhs: Self) -> Self {
             // SAFETY: the caller must uphold the safety contract for
             // `unchecked_add`.
@@ -455,7 +454,7 @@
         )]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub unsafe fn unchecked_sub(self, rhs: Self) -> Self {
             // SAFETY: the caller must uphold the safety contract for
             // `unchecked_sub`.
@@ -493,7 +492,7 @@
         )]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub unsafe fn unchecked_mul(self, rhs: Self) -> Self {
             // SAFETY: the caller must uphold the safety contract for
             // `unchecked_mul`.
@@ -742,7 +741,7 @@
         #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn saturating_add(self, rhs: Self) -> Self {
             intrinsics::saturating_add(self, rhs)
         }
@@ -763,7 +762,7 @@
         #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn saturating_sub(self, rhs: Self) -> Self {
             intrinsics::saturating_sub(self, rhs)
         }
@@ -784,7 +783,7 @@
 
         #[stable(feature = "saturating_neg", since = "1.45.0")]
         #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn saturating_neg(self) -> Self {
             intrinsics::saturating_sub(0, self)
         }
@@ -884,7 +883,7 @@
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn wrapping_add(self, rhs: Self) -> Self {
             intrinsics::wrapping_add(self, rhs)
         }
@@ -904,7 +903,7 @@
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn wrapping_sub(self, rhs: Self) -> Self {
             intrinsics::wrapping_sub(self, rhs)
         }
@@ -924,7 +923,7 @@
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn wrapping_mul(self, rhs: Self) -> Self {
             intrinsics::wrapping_mul(self, rhs)
         }
@@ -1082,7 +1081,7 @@
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn wrapping_shl(self, rhs: u32) -> Self {
             // SAFETY: the masking by the bitsize of the type ensures that we do not shift
             // out of bounds
@@ -1111,7 +1110,7 @@
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn wrapping_shr(self, rhs: u32) -> Self {
             // SAFETY: the masking by the bitsize of the type ensures that we do not shift
             // out of bounds
@@ -1226,7 +1225,7 @@
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn overflowing_add(self, rhs: Self) -> (Self, bool) {
             let (a, b) = intrinsics::add_with_overflow(self as $ActualT, rhs as $ActualT);
             (a as Self, b)
@@ -1250,7 +1249,7 @@
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn overflowing_sub(self, rhs: Self) -> (Self, bool) {
             let (a, b) = intrinsics::sub_with_overflow(self as $ActualT, rhs as $ActualT);
             (a as Self, b)
@@ -1273,7 +1272,7 @@
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn overflowing_mul(self, rhs: Self) -> (Self, bool) {
             let (a, b) = intrinsics::mul_with_overflow(self as $ActualT, rhs as $ActualT);
             (a as Self, b)
@@ -1589,11 +1588,11 @@
 
         /// Calculates the quotient of Euclidean division of `self` by `rhs`.
         ///
-        /// This computes the integer `n` such that `self = n * rhs + self.rem_euclid(rhs)`,
-        /// with `0 <= self.rem_euclid(rhs) < rhs`.
+        /// This computes the integer `q` such that `self = q * rhs + r`, with
+        /// `r = self.rem_euclid(rhs)` and `0 <= r < abs(rhs)`.
         ///
-        /// In other words, the result is `self / rhs` rounded to the integer `n`
-        /// such that `self >= n * rhs`.
+        /// In other words, the result is `self / rhs` rounded to the integer `q`
+        /// such that `self >= q * rhs`.
         /// If `self > 0`, this is equal to round towards zero (the default in Rust);
         /// if `self < 0`, this is equal to round towards +/- infinity.
         ///
@@ -1726,7 +1725,7 @@
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_int_sign", since = "1.47.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn signum(self) -> Self {
             match self {
                 n if n > 0 =>  1,
@@ -1748,7 +1747,7 @@
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn is_positive(self) -> bool { self > 0 }
 
         /// Returns `true` if `self` is negative and `false` if the number is zero or
@@ -1764,7 +1763,7 @@
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_int_methods", since = "1.32.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn is_negative(self) -> bool { self < 0 }
 
         /// Return the memory representation of this integer as a byte array in

diff --git a/library/core/src/num/mod.rs b/library/core/src/num/mod.rs
index f0bd976..6032dc9 100644
--- a/library/core/src/num/mod.rs
+++ b/library/core/src/num/mod.rs

@@ -2,6 +2,7 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
+use crate::ascii;
 use crate::intrinsics;
 use crate::mem;
 use crate::str::FromStr;
@@ -661,6 +662,31 @@
     pub const fn is_ascii_control(&self) -> bool {
         matches!(*self, b'\0'..=b'\x1F' | b'\x7F')
     }
+
+    /// Returns an iterator that produces an escaped version of a `u8`,
+    /// treating it as an ASCII character.
+    ///
+    /// The behavior is identical to [`ascii::escape_default`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(inherent_ascii_escape)]
+    ///
+    /// assert_eq!("0", b'0'.escape_ascii().to_string());
+    /// assert_eq!("\\t", b'\t'.escape_ascii().to_string());
+    /// assert_eq!("\\r", b'\r'.escape_ascii().to_string());
+    /// assert_eq!("\\n", b'\n'.escape_ascii().to_string());
+    /// assert_eq!("\\'", b'\''.escape_ascii().to_string());
+    /// assert_eq!("\\\"", b'"'.escape_ascii().to_string());
+    /// assert_eq!("\\\\", b'\\'.escape_ascii().to_string());
+    /// assert_eq!("\\x9d", b'\x9d'.escape_ascii().to_string());
+    /// ```
+    #[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+    #[inline]
+    pub fn escape_ascii(&self) -> ascii::EscapeDefault {
+        ascii::escape_default(*self)
+    }
 }
 
 #[lang = "u16"]

diff --git a/library/core/src/num/nonzero.rs b/library/core/src/num/nonzero.rs
index 111feb7..6b9b435 100644
--- a/library/core/src/num/nonzero.rs
+++ b/library/core/src/num/nonzero.rs

@@ -23,7 +23,7 @@
 }
 
 macro_rules! nonzero_integers {
-    ( $( #[$stability: meta] $Ty: ident($Int: ty); )+ ) => {
+    ( $( #[$stability: meta] #[$const_new_unchecked_stability: meta] $Ty: ident($Int: ty); )+ ) => {
         $(
             /// An integer that is known not to equal zero.
             ///
@@ -48,7 +48,7 @@
                 ///
                 /// The value must not be zero.
                 #[$stability]
-                #[rustc_const_stable(feature = "nonzero", since = "1.34.0")]
+                #[$const_new_unchecked_stability]
                 #[inline]
                 pub const unsafe fn new_unchecked(n: $Int) -> Self {
                     // SAFETY: this is guaranteed to be safe by the caller.
@@ -146,18 +146,18 @@
 }
 
 nonzero_integers! {
-    #[stable(feature = "nonzero", since = "1.28.0")] NonZeroU8(u8);
-    #[stable(feature = "nonzero", since = "1.28.0")] NonZeroU16(u16);
-    #[stable(feature = "nonzero", since = "1.28.0")] NonZeroU32(u32);
-    #[stable(feature = "nonzero", since = "1.28.0")] NonZeroU64(u64);
-    #[stable(feature = "nonzero", since = "1.28.0")] NonZeroU128(u128);
-    #[stable(feature = "nonzero", since = "1.28.0")] NonZeroUsize(usize);
-    #[stable(feature = "signed_nonzero", since = "1.34.0")] NonZeroI8(i8);
-    #[stable(feature = "signed_nonzero", since = "1.34.0")] NonZeroI16(i16);
-    #[stable(feature = "signed_nonzero", since = "1.34.0")] NonZeroI32(i32);
-    #[stable(feature = "signed_nonzero", since = "1.34.0")] NonZeroI64(i64);
-    #[stable(feature = "signed_nonzero", since = "1.34.0")] NonZeroI128(i128);
-    #[stable(feature = "signed_nonzero", since = "1.34.0")] NonZeroIsize(isize);
+    #[stable(feature = "nonzero", since = "1.28.0")] #[rustc_const_stable(feature = "nonzero", since = "1.28.0")] NonZeroU8(u8);
+    #[stable(feature = "nonzero", since = "1.28.0")] #[rustc_const_stable(feature = "nonzero", since = "1.28.0")] NonZeroU16(u16);
+    #[stable(feature = "nonzero", since = "1.28.0")] #[rustc_const_stable(feature = "nonzero", since = "1.28.0")] NonZeroU32(u32);
+    #[stable(feature = "nonzero", since = "1.28.0")] #[rustc_const_stable(feature = "nonzero", since = "1.28.0")] NonZeroU64(u64);
+    #[stable(feature = "nonzero", since = "1.28.0")] #[rustc_const_stable(feature = "nonzero", since = "1.28.0")] NonZeroU128(u128);
+    #[stable(feature = "nonzero", since = "1.28.0")] #[rustc_const_stable(feature = "nonzero", since = "1.28.0")] NonZeroUsize(usize);
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] #[rustc_const_stable(feature = "signed_nonzero", since = "1.34.0")] NonZeroI8(i8);
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] #[rustc_const_stable(feature = "signed_nonzero", since = "1.34.0")] NonZeroI16(i16);
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] #[rustc_const_stable(feature = "signed_nonzero", since = "1.34.0")] NonZeroI32(i32);
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] #[rustc_const_stable(feature = "signed_nonzero", since = "1.34.0")] NonZeroI64(i64);
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] #[rustc_const_stable(feature = "signed_nonzero", since = "1.34.0")] NonZeroI128(i128);
+    #[stable(feature = "signed_nonzero", since = "1.34.0")] #[rustc_const_stable(feature = "signed_nonzero", since = "1.34.0")] NonZeroIsize(isize);
 }
 
 macro_rules! from_str_radix_nzint_impl {
@@ -191,13 +191,12 @@
                 /// Basic usage:
                 ///
                 /// ```
-                /// #![feature(nonzero_leading_trailing_zeros)]
                 #[doc = concat!("let n = std::num::", stringify!($Ty), "::new(", stringify!($LeadingTestExpr), ").unwrap();")]
                 ///
                 /// assert_eq!(n.leading_zeros(), 0);
                 /// ```
-                #[unstable(feature = "nonzero_leading_trailing_zeros", issue = "79143")]
-                #[rustc_const_unstable(feature = "nonzero_leading_trailing_zeros", issue = "79143")]
+                #[stable(feature = "nonzero_leading_trailing_zeros", since = "1.53.0")]
+                #[rustc_const_stable(feature = "nonzero_leading_trailing_zeros", since = "1.53.0")]
                 #[inline]
                 pub const fn leading_zeros(self) -> u32 {
                     // SAFETY: since `self` can not be zero it is safe to call ctlz_nonzero
@@ -214,13 +213,12 @@
                 /// Basic usage:
                 ///
                 /// ```
-                /// #![feature(nonzero_leading_trailing_zeros)]
                 #[doc = concat!("let n = std::num::", stringify!($Ty), "::new(0b0101000).unwrap();")]
                 ///
                 /// assert_eq!(n.trailing_zeros(), 3);
                 /// ```
-                #[unstable(feature = "nonzero_leading_trailing_zeros", issue = "79143")]
-                #[rustc_const_unstable(feature = "nonzero_leading_trailing_zeros", issue = "79143")]
+                #[stable(feature = "nonzero_leading_trailing_zeros", since = "1.53.0")]
+                #[rustc_const_stable(feature = "nonzero_leading_trailing_zeros", since = "1.53.0")]
                 #[inline]
                 pub const fn trailing_zeros(self) -> u32 {
                     // SAFETY: since `self` can not be zero it is safe to call cttz_nonzero

diff --git a/library/core/src/num/uint_macros.rs b/library/core/src/num/uint_macros.rs
index 7393e7f..08d9161 100644
--- a/library/core/src/num/uint_macros.rs
+++ b/library/core/src/num/uint_macros.rs

@@ -32,10 +32,9 @@
         /// # Examples
         ///
         /// ```
-        /// #![feature(int_bits_const)]
         #[doc = concat!("assert_eq!(", stringify!($SelfT), "::BITS, ", stringify!($BITS), ");")]
         /// ```
-        #[unstable(feature = "int_bits_const", issue = "76904")]
+        #[stable(feature = "int_bits_const", since = "1.53.0")]
         pub const BITS: u32 = $BITS;
 
         /// Converts a string slice in a given base to an integer.
@@ -80,7 +79,7 @@
         #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
         #[doc(alias = "popcount")]
         #[doc(alias = "popcnt")]
-        #[inline]
+        #[inline(always)]
         pub const fn count_ones(self) -> u32 {
             intrinsics::ctpop(self as $ActualT) as u32
         }
@@ -96,7 +95,7 @@
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn count_zeros(self) -> u32 {
             (!self).count_ones()
         }
@@ -114,7 +113,7 @@
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn leading_zeros(self) -> u32 {
             intrinsics::ctlz(self as $ActualT) as u32
         }
@@ -133,7 +132,7 @@
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn trailing_zeros(self) -> u32 {
             intrinsics::cttz(self) as u32
         }
@@ -151,7 +150,7 @@
         /// ```
         #[stable(feature = "leading_trailing_ones", since = "1.46.0")]
         #[rustc_const_stable(feature = "leading_trailing_ones", since = "1.46.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn leading_ones(self) -> u32 {
             (!self).leading_zeros()
         }
@@ -170,7 +169,7 @@
         /// ```
         #[stable(feature = "leading_trailing_ones", since = "1.46.0")]
         #[rustc_const_stable(feature = "leading_trailing_ones", since = "1.46.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn trailing_ones(self) -> u32 {
             (!self).trailing_zeros()
         }
@@ -194,7 +193,7 @@
         #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn rotate_left(self, n: u32) -> Self {
             intrinsics::rotate_left(self, n as $SelfT)
         }
@@ -219,7 +218,7 @@
         #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn rotate_right(self, n: u32) -> Self {
             intrinsics::rotate_right(self, n as $SelfT)
         }
@@ -238,7 +237,7 @@
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn swap_bytes(self) -> Self {
             intrinsics::bswap(self as $ActualT) as Self
         }
@@ -258,8 +257,8 @@
         #[doc = concat!("assert_eq!(0, 0", stringify!($SelfT), ".reverse_bits());")]
         /// ```
         #[stable(feature = "reverse_bits", since = "1.37.0")]
-        #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
-        #[inline]
+        #[rustc_const_stable(feature = "const_math", since = "1.37.0")]
+        #[inline(always)]
         #[must_use]
         pub const fn reverse_bits(self) -> Self {
             intrinsics::bitreverse(self as $ActualT) as Self
@@ -285,7 +284,7 @@
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn from_be(x: Self) -> Self {
             #[cfg(target_endian = "big")]
             {
@@ -317,7 +316,7 @@
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn from_le(x: Self) -> Self {
             #[cfg(target_endian = "little")]
             {
@@ -349,7 +348,7 @@
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn to_be(self) -> Self { // or not to be?
             #[cfg(target_endian = "big")]
             {
@@ -381,7 +380,7 @@
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn to_le(self) -> Self {
             #[cfg(target_endian = "little")]
             {
@@ -427,7 +426,7 @@
         )]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub unsafe fn unchecked_add(self, rhs: Self) -> Self {
             // SAFETY: the caller must uphold the safety contract for
             // `unchecked_add`.
@@ -465,7 +464,7 @@
         )]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub unsafe fn unchecked_sub(self, rhs: Self) -> Self {
             // SAFETY: the caller must uphold the safety contract for
             // `unchecked_sub`.
@@ -503,7 +502,7 @@
         )]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub unsafe fn unchecked_mul(self, rhs: Self) -> Self {
             // SAFETY: the caller must uphold the safety contract for
             // `unchecked_mul`.
@@ -728,7 +727,7 @@
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn saturating_add(self, rhs: Self) -> Self {
             intrinsics::saturating_add(self, rhs)
         }
@@ -748,7 +747,7 @@
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
         #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn saturating_sub(self, rhs: Self) -> Self {
             intrinsics::saturating_sub(self, rhs)
         }
@@ -814,7 +813,7 @@
         #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn wrapping_add(self, rhs: Self) -> Self {
             intrinsics::wrapping_add(self, rhs)
         }
@@ -834,7 +833,7 @@
         #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn wrapping_sub(self, rhs: Self) -> Self {
             intrinsics::wrapping_sub(self, rhs)
         }
@@ -857,7 +856,7 @@
         #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                           without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn wrapping_mul(self, rhs: Self) -> Self {
             intrinsics::wrapping_mul(self, rhs)
         }
@@ -879,7 +878,7 @@
         #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.52.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn wrapping_div(self, rhs: Self) -> Self {
             self / rhs
         }
@@ -904,7 +903,7 @@
         #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn wrapping_div_euclid(self, rhs: Self) -> Self {
             self / rhs
         }
@@ -927,7 +926,7 @@
         #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.52.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn wrapping_rem(self, rhs: Self) -> Self {
             self % rhs
         }
@@ -953,7 +952,7 @@
         #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn wrapping_rem_euclid(self, rhs: Self) -> Self {
             self % rhs
         }
@@ -1009,7 +1008,7 @@
         #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn wrapping_shl(self, rhs: u32) -> Self {
             // SAFETY: the masking by the bitsize of the type ensures that we do not shift
             // out of bounds
@@ -1041,7 +1040,7 @@
         #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn wrapping_shr(self, rhs: u32) -> Self {
             // SAFETY: the masking by the bitsize of the type ensures that we do not shift
             // out of bounds
@@ -1107,7 +1106,7 @@
         #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn overflowing_add(self, rhs: Self) -> (Self, bool) {
             let (a, b) = intrinsics::add_with_overflow(self as $ActualT, rhs as $ActualT);
             (a as Self, b)
@@ -1132,7 +1131,7 @@
         #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn overflowing_sub(self, rhs: Self) -> (Self, bool) {
             let (a, b) = intrinsics::sub_with_overflow(self as $ActualT, rhs as $ActualT);
             (a as Self, b)
@@ -1159,7 +1158,7 @@
         #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                           without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn overflowing_mul(self, rhs: Self) -> (Self, bool) {
             let (a, b) = intrinsics::mul_with_overflow(self as $ActualT, rhs as $ActualT);
             (a as Self, b)
@@ -1183,7 +1182,7 @@
         /// ```
         #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_div(2), (2, false));")]
         /// ```
-        #[inline]
+        #[inline(always)]
         #[stable(feature = "wrapping", since = "1.7.0")]
         #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.52.0")]
         #[must_use = "this returns the result of the operation, \
@@ -1213,7 +1212,7 @@
         /// ```
         #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_div_euclid(2), (2, false));")]
         /// ```
-        #[inline]
+        #[inline(always)]
         #[stable(feature = "euclidean_division", since = "1.38.0")]
         #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
         #[must_use = "this returns the result of the operation, \
@@ -1240,7 +1239,7 @@
         /// ```
         #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_rem(2), (1, false));")]
         /// ```
-        #[inline]
+        #[inline(always)]
         #[stable(feature = "wrapping", since = "1.7.0")]
         #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.52.0")]
         #[must_use = "this returns the result of the operation, \
@@ -1270,7 +1269,7 @@
         /// ```
         #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_rem_euclid(2), (1, false));")]
         /// ```
-        #[inline]
+        #[inline(always)]
         #[stable(feature = "euclidean_division", since = "1.38.0")]
         #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
         #[must_use = "this returns the result of the operation, \
@@ -1294,7 +1293,7 @@
         #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".overflowing_neg(), (0, false));")]
         #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".overflowing_neg(), (-2i32 as ", stringify!($SelfT), ", true));")]
         /// ```
-        #[inline]
+        #[inline(always)]
         #[stable(feature = "wrapping", since = "1.7.0")]
         #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
         pub const fn overflowing_neg(self) -> (Self, bool) {
@@ -1321,7 +1320,7 @@
         #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn overflowing_shl(self, rhs: u32) -> (Self, bool) {
             (self.wrapping_shl(rhs), (rhs > ($BITS - 1)))
         }
@@ -1346,7 +1345,7 @@
         #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         pub const fn overflowing_shr(self, rhs: u32) -> (Self, bool) {
             (self.wrapping_shr(rhs), (rhs > ($BITS - 1)))
         }
@@ -1459,7 +1458,7 @@
         #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         #[rustc_inherit_overflow_checks]
         pub const fn div_euclid(self, rhs: Self) -> Self {
             self / rhs
@@ -1487,7 +1486,7 @@
         #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
-        #[inline]
+        #[inline(always)]
         #[rustc_inherit_overflow_checks]
         pub const fn rem_euclid(self, rhs: Self) -> Self {
             self % rhs
@@ -1505,7 +1504,7 @@
         /// ```
         #[stable(feature = "rust1", since = "1.0.0")]
         #[rustc_const_stable(feature = "const_is_power_of_two", since = "1.32.0")]
-        #[inline]
+        #[inline(always)]
         pub const fn is_power_of_two(self) -> bool {
             self.count_ones() == 1
         }

diff --git a/library/core/src/ops/arith.rs b/library/core/src/ops/arith.rs
index 92090d8..a0577b2 100644
--- a/library/core/src/ops/arith.rs
+++ b/library/core/src/ops/arith.rs

@@ -456,9 +456,13 @@
 }
 
 macro_rules! div_impl_integer {
-    ($($t:ty)*) => ($(
+    ($(($($t:ty)*) => $panic:expr),*) => ($($(
         /// This operation rounds towards zero, truncating any
         /// fractional part of the exact result.
+        ///
+        /// # Panics
+        ///
+        #[doc = $panic]
         #[stable(feature = "rust1", since = "1.0.0")]
         impl Div for $t {
             type Output = $t;
@@ -468,10 +472,13 @@
         }
 
         forward_ref_binop! { impl Div, div for $t, $t }
-    )*)
+    )*)*)
 }
 
-div_impl_integer! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }
+div_impl_integer! {
+    (usize u8 u16 u32 u64 u128) => "This operation will panic if `other == 0`.",
+    (isize i8 i16 i32 i64 i128) => "This operation will panic if `other == 0` or the division results in overflow."
+}
 
 macro_rules! div_impl_float {
     ($($t:ty)*) => ($(
@@ -549,9 +556,13 @@
 }
 
 macro_rules! rem_impl_integer {
-    ($($t:ty)*) => ($(
+    ($(($($t:ty)*) => $panic:expr),*) => ($($(
         /// This operation satisfies `n % d == n - (n / d) * d`. The
         /// result has the same sign as the left operand.
+        ///
+        /// # Panics
+        ///
+        #[doc = $panic]
         #[stable(feature = "rust1", since = "1.0.0")]
         impl Rem for $t {
             type Output = $t;
@@ -561,10 +572,13 @@
         }
 
         forward_ref_binop! { impl Rem, rem for $t, $t }
-    )*)
+    )*)*)
 }
 
-rem_impl_integer! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }
+rem_impl_integer! {
+    (usize u8 u16 u32 u64 u128) => "This operation will panic if `other == 0`.",
+    (isize i8 i16 i32 i64 i128) => "This operation will panic if `other == 0` or if `self / other` results in overflow."
+}
 
 macro_rules! rem_impl_float {
     ($($t:ty)*) => ($(

diff --git a/library/core/src/ops/control_flow.rs b/library/core/src/ops/control_flow.rs
index 2f78ba8..ecaff05 100644
--- a/library/core/src/ops/control_flow.rs
+++ b/library/core/src/ops/control_flow.rs

@@ -1,4 +1,5 @@
-use crate::ops::Try;
+use crate::convert;
+use crate::ops::{self, Try};
 
 /// Used to tell an operation whether it should exit early or go on as usual.
 ///
@@ -81,6 +82,35 @@
     }
 }
 
+#[unstable(feature = "try_trait_v2", issue = "84277")]
+impl<B, C> ops::TryV2 for ControlFlow<B, C> {
+    type Output = C;
+    type Residual = ControlFlow<B, convert::Infallible>;
+
+    #[inline]
+    fn from_output(output: Self::Output) -> Self {
+        ControlFlow::Continue(output)
+    }
+
+    #[inline]
+    fn branch(self) -> ControlFlow<Self::Residual, Self::Output> {
+        match self {
+            ControlFlow::Continue(c) => ControlFlow::Continue(c),
+            ControlFlow::Break(b) => ControlFlow::Break(ControlFlow::Break(b)),
+        }
+    }
+}
+
+#[unstable(feature = "try_trait_v2", issue = "84277")]
+impl<B, C> ops::FromResidual for ControlFlow<B, C> {
+    #[inline]
+    fn from_residual(residual: ControlFlow<B, convert::Infallible>) -> Self {
+        match residual {
+            ControlFlow::Break(b) => ControlFlow::Break(b),
+        }
+    }
+}
+
 impl<B, C> ControlFlow<B, C> {
     /// Returns `true` if this is a `Break` variant.
     ///

diff --git a/library/core/src/ops/deref.rs b/library/core/src/ops/deref.rs
index 10e3ce6..dcf3ce0 100644
--- a/library/core/src/ops/deref.rs
+++ b/library/core/src/ops/deref.rs

@@ -65,7 +65,7 @@
     /// The resulting type after dereferencing.
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_diagnostic_item = "deref_target"]
-    #[cfg_attr(not(bootstrap), lang = "deref_target")]
+    #[lang = "deref_target"]
     type Target: ?Sized;
 
     /// Dereferences the value.

diff --git a/library/core/src/ops/drop.rs b/library/core/src/ops/drop.rs
index ce7d1c3..f4b1ec3 100644
--- a/library/core/src/ops/drop.rs
+++ b/library/core/src/ops/drop.rs

@@ -78,7 +78,7 @@
 ///
 /// In other words, if you tried to explicitly call `Drop::drop` in the above example, you'd get a compiler error.
 ///
-/// If you'd like explicitly call the destructor of a value, [`mem::drop`] can be used instead.
+/// If you'd like to explicitly call the destructor of a value, [`mem::drop`] can be used instead.
 ///
 /// [`mem::drop`]: drop
 ///

diff --git a/library/core/src/ops/index.rs b/library/core/src/ops/index.rs
index a8dea4e..964378c 100644
--- a/library/core/src/ops/index.rs
+++ b/library/core/src/ops/index.rs

@@ -61,6 +61,10 @@
     type Output: ?Sized;
 
     /// Performs the indexing (`container[index]`) operation.
+    ///
+    /// # Panics
+    ///
+    /// May panic if the index is out of bounds.
     #[stable(feature = "rust1", since = "1.0.0")]
     #[track_caller]
     fn index(&self, index: Idx) -> &Self::Output;
@@ -161,6 +165,10 @@
 #[doc(alias = "[]")]
 pub trait IndexMut<Idx: ?Sized>: Index<Idx> {
     /// Performs the mutable indexing (`container[index]`) operation.
+    ///
+    /// # Panics
+    ///
+    /// May panic if the index is out of bounds.
     #[stable(feature = "rust1", since = "1.0.0")]
     #[track_caller]
     fn index_mut(&mut self, index: Idx) -> &mut Self::Output;

diff --git a/library/core/src/ops/mod.rs b/library/core/src/ops/mod.rs
index 354ad6b..1b07936 100644
--- a/library/core/src/ops/mod.rs
+++ b/library/core/src/ops/mod.rs

@@ -148,6 +148,7 @@
 mod index;
 mod range;
 mod r#try;
+mod try_trait;
 mod unsize;
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -184,6 +185,12 @@
 #[unstable(feature = "try_trait", issue = "42327")]
 pub use self::r#try::Try;
 
+#[unstable(feature = "try_trait_v2", issue = "84277")]
+pub use self::try_trait::FromResidual;
+
+#[unstable(feature = "try_trait_transition", reason = "for bootstrap", issue = "none")]
+pub use self::try_trait::Try as TryV2;
+
 #[unstable(feature = "generator_trait", issue = "43122")]
 pub use self::generator::{Generator, GeneratorState};
 

diff --git a/library/core/src/ops/try_trait.rs b/library/core/src/ops/try_trait.rs
new file mode 100644
index 0000000..0c819b0
--- /dev/null
+++ b/library/core/src/ops/try_trait.rs

@@ -0,0 +1,243 @@
+use crate::ops::ControlFlow;
+
+/// The `?` operator and `try {}` blocks.
+///
+/// `try_*` methods typically involve a type implementing this trait.  For
+/// example, the closures passed to [`Iterator::try_fold`] and
+/// [`Iterator::try_for_each`] must return such a type.
+///
+/// `Try` types are typically those containing two or more categories of values,
+/// some subset of which are so commonly handled via early returns that it's
+/// worth providing a terse (but still visible) syntax to make that easy.
+///
+/// This is most often seen for error handling with [`Result`] and [`Option`].
+/// The quintessential implementation of this trait is on [`ControlFlow`].
+///
+/// # Using `Try` in Generic Code
+///
+/// `Iterator::try_fold` was stabilized to call back in Rust 1.27, but
+/// this trait is much newer.  To illustrate the various associated types and
+/// methods, let's implement our own version.
+///
+/// As a reminder, an infallible version of a fold looks something like this:
+/// ```
+/// fn simple_fold<A, T>(
+///     iter: impl Iterator<Item = T>,
+///     mut accum: A,
+///     mut f: impl FnMut(A, T) -> A,
+/// ) -> A {
+///     for x in iter {
+///         accum = f(accum, x);
+///     }
+///     accum
+/// }
+/// ```
+///
+/// So instead of `f` returning just an `A`, we'll need it to return some other
+/// type that produces an `A` in the "don't short circuit" path.  Conveniently,
+/// that's also the type we need to return from the function.
+///
+/// Let's add a new generic parameter `R` for that type, and bound it to the
+/// output type that we want:
+/// ```
+/// # #![feature(try_trait_v2)]
+/// # #![feature(try_trait_transition)]
+/// # use std::ops::TryV2 as Try;
+/// fn simple_try_fold_1<A, T, R: Try<Output = A>>(
+///     iter: impl Iterator<Item = T>,
+///     mut accum: A,
+///     mut f: impl FnMut(A, T) -> R,
+/// ) -> R {
+///     todo!()
+/// }
+/// ```
+///
+/// If we get through the entire iterator, we need to wrap up the accumulator
+/// into the return type using [`Try::from_output`]:
+/// ```
+/// # #![feature(try_trait_v2)]
+/// # #![feature(try_trait_transition)]
+/// # #![feature(control_flow_enum)]
+/// # use std::ops::{ControlFlow, TryV2 as Try};
+/// fn simple_try_fold_2<A, T, R: Try<Output = A>>(
+///     iter: impl Iterator<Item = T>,
+///     mut accum: A,
+///     mut f: impl FnMut(A, T) -> R,
+/// ) -> R {
+///     for x in iter {
+///         let cf = f(accum, x).branch();
+///         match cf {
+///             ControlFlow::Continue(a) => accum = a,
+///             ControlFlow::Break(_) => todo!(),
+///         }
+///     }
+///     R::from_output(accum)
+/// }
+/// ```
+///
+/// We'll also need [`FromResidual::from_residual`] to turn the residual back
+/// into the original type.  But because it's a supertrait of `Try`, we don't
+/// need to mention it in the bounds.  All types which implement `Try` can be
+/// recreated from their corresponding residual, so we'll just call it:
+/// ```
+/// # #![feature(try_trait_v2)]
+/// # #![feature(try_trait_transition)]
+/// # #![feature(control_flow_enum)]
+/// # use std::ops::{ControlFlow, TryV2 as Try};
+/// pub fn simple_try_fold_3<A, T, R: Try<Output = A>>(
+///     iter: impl Iterator<Item = T>,
+///     mut accum: A,
+///     mut f: impl FnMut(A, T) -> R,
+/// ) -> R {
+///     for x in iter {
+///         let cf = f(accum, x).branch();
+///         match cf {
+///             ControlFlow::Continue(a) => accum = a,
+///             ControlFlow::Break(r) => return R::from_residual(r),
+///         }
+///     }
+///     R::from_output(accum)
+/// }
+/// ```
+///
+/// But this "call `branch`, then `match` on it, and `return` if it was a
+/// `Break`" is exactly what happens inside the `?` operator.  So rather than
+/// do all this manually, we can just use `?` instead:
+/// ```compile_fail (enable again once ? converts to the new trait)
+/// # #![feature(try_trait_v2)]
+/// # #![feature(try_trait_transition)]
+/// # use std::ops::TryV2 as Try;
+/// fn simple_try_fold<A, T, R: Try<Output = A>>(
+///     iter: impl Iterator<Item = T>,
+///     mut accum: A,
+///     mut f: impl FnMut(A, T) -> R,
+/// ) -> R {
+///     for x in iter {
+///         accum = f(accum, x)?;
+///     }
+///     R::from_output(accum)
+/// }
+/// ```
+#[unstable(feature = "try_trait_v2", issue = "84277")]
+pub trait Try: FromResidual {
+    /// The type of the value produced by `?` when *not* short-circuiting.
+    #[unstable(feature = "try_trait_v2", issue = "84277")]
+    type Output;
+
+    /// The type of the value passed to [`FromResidual::from_residual`]
+    /// as part of `?` when short-circuiting.
+    ///
+    /// This represents the possible values of the `Self` type which are *not*
+    /// represented by the `Output` type.
+    ///
+    /// # Note to Implementors
+    ///
+    /// The choice of this type is critical to interconversion.
+    /// Unlike the `Output` type, which will often be a raw generic type,
+    /// this type is typically a newtype of some sort to "color" the type
+    /// so that it's distinguishable from the residuals of other types.
+    ///
+    /// This is why `Result<T, E>::Residual` is not `E`, but `Result<Infallible, E>`.
+    /// That way it's distinct from `ControlFlow<E>::Residual`, for example,
+    /// and thus `?` on `ControlFlow` cannot be used in a method returning `Result`.
+    ///
+    /// If you're making a generic type `Foo<T>` that implements `Try<Output = T>`,
+    /// then typically you can use `Foo<std::convert::Infallible>` as its `Residual`
+    /// type: that type will have a "hole" in the correct place, and will maintain the
+    /// "foo-ness" of the residual so other types need to opt-in to interconversion.
+    #[unstable(feature = "try_trait_v2", issue = "84277")]
+    type Residual;
+
+    /// Constructs the type from its `Output` type.
+    ///
+    /// This should be implemented consistently with the `branch` method
+    /// such that applying the `?` operator will get back the original value:
+    /// `Try::from_output(x).branch() --> ControlFlow::Continue(x)`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(try_trait_v2)]
+    /// #![feature(control_flow_enum)]
+    /// #![feature(try_trait_transition)]
+    /// use std::ops::TryV2 as Try;
+    ///
+    /// assert_eq!(<Result<_, String> as Try>::from_output(3), Ok(3));
+    /// assert_eq!(<Option<_> as Try>::from_output(4), Some(4));
+    /// assert_eq!(
+    ///     <std::ops::ControlFlow<String, _> as Try>::from_output(5),
+    ///     std::ops::ControlFlow::Continue(5),
+    /// );
+    ///
+    /// # fn make_question_mark_work() -> Option<()> {
+    /// assert_eq!(Option::from_output(4)?, 4);
+    /// # None }
+    /// # make_question_mark_work();
+    ///
+    /// // This is used, for example, on the accumulator in `try_fold`:
+    /// let r = std::iter::empty().try_fold(4, |_, ()| -> Option<_> { unreachable!() });
+    /// assert_eq!(r, Some(4));
+    /// ```
+    #[unstable(feature = "try_trait_v2", issue = "84277")]
+    fn from_output(output: Self::Output) -> Self;
+
+    /// Used in `?` to decide whether the operator should produce a value
+    /// (because this returned [`ControlFlow::Continue`])
+    /// or propagate a value back to the caller
+    /// (because this returned [`ControlFlow::Break`]).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(try_trait_v2)]
+    /// #![feature(control_flow_enum)]
+    /// #![feature(try_trait_transition)]
+    /// use std::ops::{ControlFlow, TryV2 as Try};
+    ///
+    /// assert_eq!(Ok::<_, String>(3).branch(), ControlFlow::Continue(3));
+    /// assert_eq!(Err::<String, _>(3).branch(), ControlFlow::Break(Err(3)));
+    ///
+    /// assert_eq!(Some(3).branch(), ControlFlow::Continue(3));
+    /// assert_eq!(None::<String>.branch(), ControlFlow::Break(None));
+    ///
+    /// assert_eq!(ControlFlow::<String, _>::Continue(3).branch(), ControlFlow::Continue(3));
+    /// assert_eq!(
+    ///     ControlFlow::<_, String>::Break(3).branch(),
+    ///     ControlFlow::Break(ControlFlow::Break(3)),
+    /// );
+    /// ```
+    #[unstable(feature = "try_trait_v2", issue = "84277")]
+    fn branch(self) -> ControlFlow<Self::Residual, Self::Output>;
+}
+
+/// Used to specify which residuals can be converted into which [`Try`] types.
+///
+/// Every `Try` type needs to be recreatable from its own associated
+/// `Residual` type, but can also have additional `FromResidual` implementations
+/// to support interconversion with other `Try` types.
+#[unstable(feature = "try_trait_v2", issue = "84277")]
+pub trait FromResidual<R = <Self as Try>::Residual> {
+    /// Constructs the type from a compatible `Residual` type.
+    ///
+    /// This should be implemented consistently with the `branch` method such
+    /// that applying the `?` operator will get back an equivalent residual:
+    /// `FromResidual::from_residual(r).branch() --> ControlFlow::Break(r)`.
+    /// (It may not be an *identical* residual when interconversion is involved.)
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(try_trait_v2)]
+    /// #![feature(control_flow_enum)]
+    /// use std::ops::{ControlFlow, FromResidual};
+    ///
+    /// assert_eq!(Result::<String, i64>::from_residual(Err(3_u8)), Err(3));
+    /// assert_eq!(Option::<String>::from_residual(None), None);
+    /// assert_eq!(
+    ///     ControlFlow::<_, String>::from_residual(ControlFlow::Break(5)),
+    ///     ControlFlow::Break(5),
+    /// );
+    /// ```
+    #[unstable(feature = "try_trait_v2", issue = "84277")]
+    fn from_residual(residual: R) -> Self;
+}

diff --git a/library/core/src/option.rs b/library/core/src/option.rs
index f1a0f45..04551dd 100644
--- a/library/core/src/option.rs
+++ b/library/core/src/option.rs

@@ -150,8 +150,8 @@
 use crate::iter::{FromIterator, FusedIterator, TrustedLen};
 use crate::pin::Pin;
 use crate::{
-    fmt, hint, mem,
-    ops::{self, Deref, DerefMut},
+    convert, hint, mem,
+    ops::{self, ControlFlow, Deref, DerefMut},
 };
 
 /// The `Option` type. See [the module level documentation](self) for more.
@@ -489,8 +489,8 @@
         }
     }
 
-    /// Applies a function to the contained value (if any),
-    /// or returns the provided default (if not).
+    /// Returns the provided default result (if none),
+    /// or applies a function to the contained value (if any).
     ///
     /// Arguments passed to `map_or` are eagerly evaluated; if you are passing
     /// the result of a function call, it is recommended to use [`map_or_else`],
@@ -516,8 +516,8 @@
         }
     }
 
-    /// Applies a function to the contained value (if any),
-    /// or computes a default (if not).
+    /// Computes a default function result (if none), or
+    /// applies a different function to the contained value (if any).
     ///
     /// # Examples
     ///
@@ -594,36 +594,6 @@
         }
     }
 
-    /// Inserts `value` into the option then returns a mutable reference to it.
-    ///
-    /// If the option already contains a value, the old value is dropped.
-    ///
-    /// # Example
-    ///
-    /// ```
-    /// #![feature(option_insert)]
-    ///
-    /// let mut opt = None;
-    /// let val = opt.insert(1);
-    /// assert_eq!(*val, 1);
-    /// assert_eq!(opt.unwrap(), 1);
-    /// let val = opt.insert(2);
-    /// assert_eq!(*val, 2);
-    /// *val = 3;
-    /// assert_eq!(opt.unwrap(), 3);
-    /// ```
-    #[inline]
-    #[unstable(feature = "option_insert", reason = "newly added", issue = "78271")]
-    pub fn insert(&mut self, value: T) -> &mut T {
-        *self = Some(value);
-
-        match self {
-            Some(v) => v,
-            // SAFETY: the code above just filled the option
-            None => unsafe { hint::unreachable_unchecked() },
-        }
-    }
-
     /////////////////////////////////////////////////////////////////////////
     // Iterator constructors
     /////////////////////////////////////////////////////////////////////////
@@ -851,12 +821,46 @@
     }
 
     /////////////////////////////////////////////////////////////////////////
-    // Entry-like operations to insert if None and return a reference
+    // Entry-like operations to insert a value and return a reference
     /////////////////////////////////////////////////////////////////////////
 
+    /// Inserts `value` into the option then returns a mutable reference to it.
+    ///
+    /// If the option already contains a value, the old value is dropped.
+    ///
+    /// See also [`Option::get_or_insert`], which doesn't update the value if
+    /// the option already contains [`Some`].
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// let mut opt = None;
+    /// let val = opt.insert(1);
+    /// assert_eq!(*val, 1);
+    /// assert_eq!(opt.unwrap(), 1);
+    /// let val = opt.insert(2);
+    /// assert_eq!(*val, 2);
+    /// *val = 3;
+    /// assert_eq!(opt.unwrap(), 3);
+    /// ```
+    #[inline]
+    #[stable(feature = "option_insert", since = "1.53.0")]
+    pub fn insert(&mut self, value: T) -> &mut T {
+        *self = Some(value);
+
+        match self {
+            Some(v) => v,
+            // SAFETY: the code above just filled the option
+            None => unsafe { hint::unreachable_unchecked() },
+        }
+    }
+
     /// Inserts `value` into the option if it is [`None`], then
     /// returns a mutable reference to the contained value.
     ///
+    /// See also [`Option::insert`], which updates the value even if
+    /// the option already contains [`Some`].
+    ///
     /// # Examples
     ///
     /// ```
@@ -1121,90 +1125,6 @@
     }
 }
 
-impl<T: fmt::Debug> Option<T> {
-    /// Consumes `self` while expecting [`None`] and returning nothing.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the value is a [`Some`], with a panic message including the
-    /// passed message, and the content of the [`Some`].
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(option_expect_none)]
-    ///
-    /// use std::collections::HashMap;
-    /// let mut squares = HashMap::new();
-    /// for i in -10..=10 {
-    ///     // This will not panic, since all keys are unique.
-    ///     squares.insert(i, i * i).expect_none("duplicate key");
-    /// }
-    /// ```
-    ///
-    /// ```should_panic
-    /// #![feature(option_expect_none)]
-    ///
-    /// use std::collections::HashMap;
-    /// let mut sqrts = HashMap::new();
-    /// for i in -10..=10 {
-    ///     // This will panic, since both negative and positive `i` will
-    ///     // insert the same `i * i` key, returning the old `Some(i)`.
-    ///     sqrts.insert(i * i, i).expect_none("duplicate key");
-    /// }
-    /// ```
-    #[inline]
-    #[track_caller]
-    #[unstable(feature = "option_expect_none", reason = "newly added", issue = "62633")]
-    pub fn expect_none(self, msg: &str) {
-        if let Some(val) = self {
-            expect_none_failed(msg, &val);
-        }
-    }
-
-    /// Consumes `self` while expecting [`None`] and returning nothing.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the value is a [`Some`], with a custom panic message provided
-    /// by the [`Some`]'s value.
-    ///
-    /// [`Some(v)`]: Some
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// #![feature(option_unwrap_none)]
-    ///
-    /// use std::collections::HashMap;
-    /// let mut squares = HashMap::new();
-    /// for i in -10..=10 {
-    ///     // This will not panic, since all keys are unique.
-    ///     squares.insert(i, i * i).unwrap_none();
-    /// }
-    /// ```
-    ///
-    /// ```should_panic
-    /// #![feature(option_unwrap_none)]
-    ///
-    /// use std::collections::HashMap;
-    /// let mut sqrts = HashMap::new();
-    /// for i in -10..=10 {
-    ///     // This will panic, since both negative and positive `i` will
-    ///     // insert the same `i * i` key, returning the old `Some(i)`.
-    ///     sqrts.insert(i * i, i).unwrap_none();
-    /// }
-    /// ```
-    #[inline]
-    #[track_caller]
-    #[unstable(feature = "option_unwrap_none", reason = "newly added", issue = "62633")]
-    pub fn unwrap_none(self) {
-        if let Some(val) = self {
-            expect_none_failed("called `Option::unwrap_none()` on a `Some` value", &val);
-        }
-    }
-}
-
 impl<T: Default> Option<T> {
     /// Returns the contained [`Some`] value or a default
     ///
@@ -1321,14 +1241,6 @@
     panic!("{}", msg)
 }
 
-// This is a separate function to reduce the code size of .expect_none() itself.
-#[inline(never)]
-#[cold]
-#[track_caller]
-fn expect_none_failed(msg: &str, value: &dyn fmt::Debug) -> ! {
-    panic!("{}: {:?}", msg, value)
-}
-
 /////////////////////////////////////////////////////////////////////////////
 // Trait implementations
 /////////////////////////////////////////////////////////////////////////////
@@ -1752,6 +1664,35 @@
     }
 }
 
+#[unstable(feature = "try_trait_v2", issue = "84277")]
+impl<T> ops::TryV2 for Option<T> {
+    type Output = T;
+    type Residual = Option<convert::Infallible>;
+
+    #[inline]
+    fn from_output(output: Self::Output) -> Self {
+        Some(output)
+    }
+
+    #[inline]
+    fn branch(self) -> ControlFlow<Self::Residual, Self::Output> {
+        match self {
+            Some(v) => ControlFlow::Continue(v),
+            None => ControlFlow::Break(None),
+        }
+    }
+}
+
+#[unstable(feature = "try_trait_v2", issue = "84277")]
+impl<T> ops::FromResidual for Option<T> {
+    #[inline]
+    fn from_residual(residual: Option<convert::Infallible>) -> Self {
+        match residual {
+            None => None,
+        }
+    }
+}
+
 impl<T> Option<Option<T>> {
     /// Converts from `Option<Option<T>>` to `Option<T>`
     ///

diff --git a/library/core/src/pin.rs b/library/core/src/pin.rs
index b2de0e1..3d88829 100644
--- a/library/core/src/pin.rs
+++ b/library/core/src/pin.rs

@@ -6,7 +6,7 @@
 //! as moving an object with pointers to itself will invalidate them, which could cause undefined
 //! behavior.
 //!
-//! At a high level, a [`Pin<P>`] ensures that the pointee of any pointer type
+//! At a high level, a <code>[Pin]\<P></code> ensures that the pointee of any pointer type
 //! `P` has a stable location in memory, meaning it cannot be moved elsewhere
 //! and its memory cannot be deallocated until it gets dropped. We say that the
 //! pointee is "pinned". Things get more subtle when discussing types that
@@ -14,13 +14,15 @@
 //! for more details.
 //!
 //! By default, all types in Rust are movable. Rust allows passing all types by-value,
-//! and common smart-pointer types such as [`Box<T>`] and `&mut T` allow replacing and
-//! moving the values they contain: you can move out of a [`Box<T>`], or you can use [`mem::swap`].
-//! [`Pin<P>`] wraps a pointer type `P`, so [`Pin`]`<`[`Box`]`<T>>` functions much like a regular
-//! [`Box<T>`]: when a [`Pin`]`<`[`Box`]`<T>>` gets dropped, so do its contents, and the memory gets
-//! deallocated. Similarly, [`Pin`]`<&mut T>` is a lot like `&mut T`. However, [`Pin<P>`] does
-//! not let clients actually obtain a [`Box<T>`] or `&mut T` to pinned data, which implies that you
-//! cannot use operations such as [`mem::swap`]:
+//! and common smart-pointer types such as <code>[Box]\<T></code> and <code>[&mut] T</code> allow
+//! replacing and moving the values they contain: you can move out of a <code>[Box]\<T></code>,
+//! or you can use [`mem::swap`]. <code>[Pin]\<P></code> wraps a pointer type `P`, so
+//! <code>[Pin]<[Box]\<T>></code> functions much like a regular <code>[Box]\<T></code>:
+//! when a <code>[Pin]<[Box]\<T>></code> gets dropped, so do its contents, and the memory gets
+//! deallocated. Similarly, <code>[Pin]<[&mut] T></code> is a lot like <code>[&mut] T</code>.
+//! However, <code>[Pin]\<P></code> does not let clients actually obtain a <code>[Box]\<T></code>
+//! or <code>[&mut] T</code> to pinned data, which implies that you cannot use operations such
+//! as [`mem::swap`]:
 //!
 //! ```
 //! use std::pin::Pin;
@@ -32,18 +34,18 @@
 //! }
 //! ```
 //!
-//! It is worth reiterating that [`Pin<P>`] does *not* change the fact that a Rust compiler
-//! considers all types movable. [`mem::swap`] remains callable for any `T`. Instead, [`Pin<P>`]
-//! prevents certain *values* (pointed to by pointers wrapped in [`Pin<P>`]) from being
-//! moved by making it impossible to call methods that require `&mut T` on them
-//! (like [`mem::swap`]).
+//! It is worth reiterating that <code>[Pin]\<P></code> does *not* change the fact that a Rust
+//! compiler considers all types movable. [`mem::swap`] remains callable for any `T`. Instead,
+//! <code>[Pin]\<P></code> prevents certain *values* (pointed to by pointers wrapped in
+//! <code>[Pin]\<P></code>) from being moved by making it impossible to call methods that require
+//! <code>[&mut] T</code> on them (like [`mem::swap`]).
 //!
-//! [`Pin<P>`] can be used to wrap any pointer type `P`, and as such it interacts with
-//! [`Deref`] and [`DerefMut`]. A [`Pin<P>`] where `P: Deref` should be considered
-//! as a "`P`-style pointer" to a pinned `P::Target` -- so, a [`Pin`]`<`[`Box`]`<T>>` is
-//! an owned pointer to a pinned `T`, and a [`Pin`]`<`[`Rc`]`<T>>` is a reference-counted
-//! pointer to a pinned `T`.
-//! For correctness, [`Pin<P>`] relies on the implementations of [`Deref`] and
+//! <code>[Pin]\<P></code> can be used to wrap any pointer type `P`, and as such it interacts with
+//! [`Deref`] and [`DerefMut`]. A <code>[Pin]\<P></code> where <code>P: [Deref]</code> should be
+//! considered as a "`P`-style pointer" to a pinned <code>P::[Target]</code> – so, a
+//! <code>[Pin]<[Box]\<T>></code> is an owned pointer to a pinned `T`, and a
+//! <code>[Pin]<[Rc]\<T>></code> is a reference-counted pointer to a pinned `T`.
+//! For correctness, <code>[Pin]\<P></code> relies on the implementations of [`Deref`] and
 //! [`DerefMut`] not to move out of their `self` parameter, and only ever to
 //! return a pointer to pinned data when they are called on a pinned pointer.
 //!
@@ -53,19 +55,19 @@
 //! rely on having a stable address. This includes all the basic types (like
 //! [`bool`], [`i32`], and references) as well as types consisting solely of these
 //! types. Types that do not care about pinning implement the [`Unpin`]
-//! auto-trait, which cancels the effect of [`Pin<P>`]. For `T: Unpin`,
-//! [`Pin`]`<`[`Box`]`<T>>` and [`Box<T>`] function identically, as do [`Pin`]`<&mut T>` and
-//! `&mut T`.
+//! auto-trait, which cancels the effect of <code>[Pin]\<P></code>. For <code>T: [Unpin]</code>,
+//! <code>[Pin]<[Box]\<T>></code> and <code>[Box]\<T></code> function identically, as do
+//! <code>[Pin]<[&mut] T></code> and <code>[&mut] T</code>.
 //!
-//! Note that pinning and [`Unpin`] only affect the pointed-to type `P::Target`, not the pointer
-//! type `P` itself that got wrapped in [`Pin<P>`]. For example, whether or not [`Box<T>`] is
-//! [`Unpin`] has no effect on the behavior of [`Pin`]`<`[`Box`]`<T>>` (here, `T` is the
-//! pointed-to type).
+//! Note that pinning and [`Unpin`] only affect the pointed-to type <code>P::[Target]</code>,
+//! not the pointer type `P` itself that got wrapped in <code>[Pin]\<P></code>. For example,
+//! whether or not <code>[Box]\<T></code> is [`Unpin`] has no effect on the behavior of
+//! <code>[Pin]<[Box]\<T>></code> (here, `T` is the pointed-to type).
 //!
 //! # Example: self-referential struct
 //!
 //! Before we go into more details to explain the guarantees and choices
-//! associated with `Pin<T>`, we discuss some examples for how it might be used.
+//! associated with <code>[Pin]\<P></code>, we discuss some examples for how it might be used.
 //! Feel free to [skip to where the theoretical discussion continues](#drop-guarantee).
 //!
 //! ```rust
@@ -129,7 +131,7 @@
 //!
 //! To make this work, every element has pointers to its predecessor and successor in
 //! the list. Elements can only be added when they are pinned, because moving the elements
-//! around would invalidate the pointers. Moreover, the [`Drop`] implementation of a linked
+//! around would invalidate the pointers. Moreover, the [`Drop`][Drop] implementation of a linked
 //! list element will patch the pointers of its predecessor and successor to remove itself
 //! from the list.
 //!
@@ -149,8 +151,8 @@
 //! when [`drop`] is called*.  Only once [`drop`] returns or panics, the memory may be reused.
 //!
 //! Memory can be "invalidated" by deallocation, but also by
-//! replacing a [`Some(v)`] by [`None`], or calling [`Vec::set_len`] to "kill" some elements
-//! off of a vector. It can be repurposed by using [`ptr::write`] to overwrite it without
+//! replacing a <code>[Some]\(v)</code> by [`None`], or calling [`Vec::set_len`] to "kill" some
+//! elements off of a vector. It can be repurposed by using [`ptr::write`] to overwrite it without
 //! calling the destructor first. None of this is allowed for pinned data without calling [`drop`].
 //!
 //! This is exactly the kind of guarantee that the intrusive linked list from the previous
@@ -158,25 +160,25 @@
 //!
 //! Notice that this guarantee does *not* mean that memory does not leak! It is still
 //! completely okay not ever to call [`drop`] on a pinned element (e.g., you can still
-//! call [`mem::forget`] on a [`Pin`]`<`[`Box`]`<T>>`). In the example of the doubly-linked
+//! call [`mem::forget`] on a <code>[Pin]<[Box]\<T>></code>). In the example of the doubly-linked
 //! list, that element would just stay in the list. However you may not free or reuse the storage
 //! *without calling [`drop`]*.
 //!
 //! # `Drop` implementation
 //!
 //! If your type uses pinning (such as the two examples above), you have to be careful
-//! when implementing [`Drop`]. The [`drop`] function takes `&mut self`, but this
+//! when implementing [`Drop`][Drop]. The [`drop`] function takes <code>[&mut] self</code>, but this
 //! is called *even if your type was previously pinned*! It is as if the
 //! compiler automatically called [`Pin::get_unchecked_mut`].
 //!
 //! This can never cause a problem in safe code because implementing a type that
 //! relies on pinning requires unsafe code, but be aware that deciding to make
 //! use of pinning in your type (for example by implementing some operation on
-//! [`Pin`]`<&Self>` or [`Pin`]`<&mut Self>`) has consequences for your [`Drop`]
-//! implementation as well: if an element of your type could have been pinned,
-//! you must treat [`Drop`] as implicitly taking [`Pin`]`<&mut Self>`.
+//! <code>[Pin]<[&]Self></code> or <code>[Pin]<[&mut] Self></code>) has consequences for your
+//! [`Drop`][Drop]implementation as well: if an element of your type could have been pinned,
+//! you must treat [`Drop`][Drop] as implicitly taking <code>[Pin]<[&mut] Self></code>.
 //!
-//! For example, you could implement `Drop` as follows:
+//! For example, you could implement [`Drop`][Drop] as follows:
 //!
 //! ```rust,no_run
 //! # use std::pin::Pin;
@@ -204,18 +206,18 @@
 //! # Projections and Structural Pinning
 //!
 //! When working with pinned structs, the question arises how one can access the
-//! fields of that struct in a method that takes just [`Pin`]`<&mut Struct>`.
+//! fields of that struct in a method that takes just <code>[Pin]<[&mut] Struct></code>.
 //! The usual approach is to write helper methods (so called *projections*)
-//! that turn [`Pin`]`<&mut Struct>` into a reference to the field, but what
-//! type should that reference have? Is it [`Pin`]`<&mut Field>` or `&mut Field`?
+//! that turn <code>[Pin]<[&mut] Struct></code> into a reference to the field, but what type should
+//! that reference have? Is it <code>[Pin]<[&mut] Field></code> or <code>[&mut] Field</code>?
 //! The same question arises with the fields of an `enum`, and also when considering
-//! container/wrapper types such as [`Vec<T>`], [`Box<T>`], or [`RefCell<T>`].
-//! (This question applies to both mutable and shared references, we just
-//! use the more common case of mutable references here for illustration.)
+//! container/wrapper types such as <code>[Vec]\<T></code>, <code>[Box]\<T></code>,
+//! or <code>[RefCell]\<T></code>. (This question applies to both mutable and shared references,
+//! we just use the more common case of mutable references here for illustration.)
 //!
-//! It turns out that it is actually up to the author of the data structure
-//! to decide whether the pinned projection for a particular field turns
-//! [`Pin`]`<&mut Struct>` into [`Pin`]`<&mut Field>` or `&mut Field`. There are some
+//! It turns out that it is actually up to the author of the data structure to decide whether
+//! the pinned projection for a particular field turns <code>[Pin]<[&mut] Struct></code>
+//! into <code>[Pin]<[&mut] Field></code> or <code>[&mut] Field</code>. There are some
 //! constraints though, and the most important constraint is *consistency*:
 //! every field can be *either* projected to a pinned reference, *or* have
 //! pinning removed as part of the projection. If both are done for the same field,
@@ -230,12 +232,12 @@
 //! ## Pinning *is not* structural for `field`
 //!
 //! It may seem counter-intuitive that the field of a pinned struct might not be pinned,
-//! but that is actually the easiest choice: if a [`Pin`]`<&mut Field>` is never created,
+//! but that is actually the easiest choice: if a <code>[Pin]<[&mut] Field></code> is never created,
 //! nothing can go wrong! So, if you decide that some field does not have structural pinning,
 //! all you have to ensure is that you never create a pinned reference to that field.
 //!
 //! Fields without structural pinning may have a projection method that turns
-//! [`Pin`]`<&mut Struct>` into `&mut Field`:
+//! <code>[Pin]<[&mut] Struct></code> into <code>[&mut] Field</code>:
 //!
 //! ```rust,no_run
 //! # use std::pin::Pin;
@@ -249,16 +251,16 @@
 //! }
 //! ```
 //!
-//! You may also `impl Unpin for Struct` *even if* the type of `field`
+//! You may also <code>impl [Unpin] for Struct</code> *even if* the type of `field`
 //! is not [`Unpin`]. What that type thinks about pinning is not relevant
-//! when no [`Pin`]`<&mut Field>` is ever created.
+//! when no <code>[Pin]<[&mut] Field></code> is ever created.
 //!
 //! ## Pinning *is* structural for `field`
 //!
 //! The other option is to decide that pinning is "structural" for `field`,
 //! meaning that if the struct is pinned then so is the field.
 //!
-//! This allows writing a projection that creates a [`Pin`]`<&mut Field>`, thus
+//! This allows writing a projection that creates a <code>[Pin]<[&mut] Field></code>, thus
 //! witnessing that the field is pinned:
 //!
 //! ```rust,no_run
@@ -278,34 +280,36 @@
 //! 1.  The struct must only be [`Unpin`] if all the structural fields are
 //!     [`Unpin`]. This is the default, but [`Unpin`] is a safe trait, so as the author of
 //!     the struct it is your responsibility *not* to add something like
-//!     `impl<T> Unpin for Struct<T>`. (Notice that adding a projection operation
+//!     <code>impl\<T> [Unpin] for Struct\<T></code>. (Notice that adding a projection operation
 //!     requires unsafe code, so the fact that [`Unpin`] is a safe trait does not break
-//!     the principle that you only have to worry about any of this if you use `unsafe`.)
+//!     the principle that you only have to worry about any of this if you use [`unsafe`].)
 //! 2.  The destructor of the struct must not move structural fields out of its argument. This
-//!     is the exact point that was raised in the [previous section][drop-impl]: `drop` takes
-//!     `&mut self`, but the struct (and hence its fields) might have been pinned before.
-//!     You have to guarantee that you do not move a field inside your [`Drop`] implementation.
-//!     In particular, as explained previously, this means that your struct must *not*
-//!     be `#[repr(packed)]`.
+//!     is the exact point that was raised in the [previous section][drop-impl]: [`drop`] takes
+//!     <code>[&mut] self</code>, but the struct (and hence its fields) might have been pinned
+//!     before. You have to guarantee that you do not move a field inside your [`Drop`][Drop]
+//!     implementation. In particular, as explained previously, this means that your struct
+//!     must *not* be `#[repr(packed)]`.
 //!     See that section for how to write [`drop`] in a way that the compiler can help you
 //!     not accidentally break pinning.
 //! 3.  You must make sure that you uphold the [`Drop` guarantee][drop-guarantee]:
 //!     once your struct is pinned, the memory that contains the
 //!     content is not overwritten or deallocated without calling the content's destructors.
-//!     This can be tricky, as witnessed by [`VecDeque<T>`]: the destructor of [`VecDeque<T>`]
-//!     can fail to call [`drop`] on all elements if one of the destructors panics. This violates
-//!     the [`Drop`] guarantee, because it can lead to elements being deallocated without
-//!     their destructor being called. ([`VecDeque<T>`] has no pinning projections, so this
+//!     This can be tricky, as witnessed by <code>[VecDeque]\<T></code>: the destructor of
+//!     <code>[VecDeque]\<T></code> can fail to call [`drop`] on all elements if one of the
+//!     destructors panics. This violates the [`Drop`][Drop] guarantee, because it can lead to
+//!     elements being deallocated without their destructor being called.
+//!     (<code>[VecDeque]\<T></code> has no pinning projections, so this
 //!     does not cause unsoundness.)
 //! 4.  You must not offer any other operations that could lead to data being moved out of
 //!     the structural fields when your type is pinned. For example, if the struct contains an
-//!     [`Option<T>`] and there is a `take`-like operation with type
-//!     `fn(Pin<&mut Struct<T>>) -> Option<T>`,
-//!     that operation can be used to move a `T` out of a pinned `Struct<T>` -- which means
+//!     <code>[Option]\<T></code> and there is a [`take`][Option::take]-like operation with type
+//!     <code>fn([Pin]<[&mut] Struct\<T>>) -> [Option]\<T></code>,
+//!     that operation can be used to move a `T` out of a pinned `Struct<T>` – which means
 //!     pinning cannot be structural for the field holding this data.
 //!
-//!     For a more complex example of moving data out of a pinned type, imagine if [`RefCell<T>`]
-//!     had a method `fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut T>`.
+//!     For a more complex example of moving data out of a pinned type,
+//!     imagine if <code>[RefCell]\<T></code> had a method
+//!     <code>fn get_pin_mut(self: [Pin]<[&mut] Self>) -> [Pin]<[&mut] T></code>.
 //!     Then we could do the following:
 //!     ```compile_fail
 //!     fn exploit_ref_cell<T>(rc: Pin<&mut RefCell<T>>) {
@@ -315,60 +319,65 @@
 //!         let content = &mut *b; // And here we have `&mut T` to the same data.
 //!     }
 //!     ```
-//!     This is catastrophic, it means we can first pin the content of the [`RefCell<T>`]
-//!     (using `RefCell::get_pin_mut`) and then move that content using the mutable
-//!     reference we got later.
+//!     This is catastrophic, it means we can first pin the content of the
+//!     <code>[RefCell]\<T></code> (using <code>[RefCell]::get_pin_mut</code>) and then move that
+//!     content using the mutable reference we got later.
 //!
 //! ## Examples
 //!
-//! For a type like [`Vec<T>`], both possibilities (structural pinning or not) make sense.
-//! A [`Vec<T>`] with structural pinning could have `get_pin`/`get_pin_mut` methods to get
-//! pinned references to elements. However, it could *not* allow calling
-//! [`pop`][Vec::pop] on a pinned [`Vec<T>`] because that would move the (structurally pinned)
-//! contents! Nor could it allow [`push`][Vec::push], which might reallocate and thus also move the
-//! contents.
+//! For a type like <code>[Vec]\<T></code>, both possibilities (structural pinning or not) make
+//! sense. A <code>[Vec]\<T></code> with structural pinning could have `get_pin`/`get_pin_mut`
+//! methods to get pinned references to elements. However, it could *not* allow calling
+//! [`pop`][Vec::pop] on a pinned <code>[Vec]\<T></code> because that would move the (structurally
+//! pinned) contents! Nor could it allow [`push`][Vec::push], which might reallocate and thus also
+//! move the contents.
 //!
-//! A [`Vec<T>`] without structural pinning could `impl<T> Unpin for Vec<T>`, because the contents
-//! are never pinned and the [`Vec<T>`] itself is fine with being moved as well.
+//! A <code>[Vec]\<T></code> without structural pinning could
+//! <code>impl\<T> [Unpin] for [Vec]\<T></code>, because the contents are never pinned
+//! and the <code>[Vec]\<T></code> itself is fine with being moved as well.
 //! At that point pinning just has no effect on the vector at all.
 //!
 //! In the standard library, pointer types generally do not have structural pinning,
-//! and thus they do not offer pinning projections. This is why `Box<T>: Unpin` holds for all `T`.
-//! It makes sense to do this for pointer types, because moving the `Box<T>`
-//! does not actually move the `T`: the [`Box<T>`] can be freely movable (aka `Unpin`) even if
-//! the `T` is not. In fact, even [`Pin`]`<`[`Box`]`<T>>` and [`Pin`]`<&mut T>` are always
-//! [`Unpin`] themselves, for the same reason: their contents (the `T`) are pinned, but the
-//! pointers themselves can be moved without moving the pinned data. For both [`Box<T>`] and
-//! [`Pin`]`<`[`Box`]`<T>>`, whether the content is pinned is entirely independent of whether the
+//! and thus they do not offer pinning projections. This is why <code>[Box]\<T>: [Unpin]</code>
+//! holds for all `T`. It makes sense to do this for pointer types, because moving the
+//! <code>[Box]\<T></code> does not actually move the `T`: the <code>[Box]\<T></code> can be freely
+//! movable (aka [`Unpin`]) even if the `T` is not. In fact, even <code>[Pin]<[Box]\<T>></code> and
+//! <code>[Pin]<[&mut] T></code> are always [`Unpin`] themselves, for the same reason:
+//! their contents (the `T`) are pinned, but the pointers themselves can be moved without moving
+//! the pinned data. For both <code>[Box]\<T></code> and <code>[Pin]<[Box]\<T>></code>,
+//! whether the content is pinned is entirely independent of whether the
 //! pointer is pinned, meaning pinning is *not* structural.
 //!
 //! When implementing a [`Future`] combinator, you will usually need structural pinning
 //! for the nested futures, as you need to get pinned references to them to call [`poll`].
 //! But if your combinator contains any other data that does not need to be pinned,
 //! you can make those fields not structural and hence freely access them with a
-//! mutable reference even when you just have [`Pin`]`<&mut Self>` (such as in your own
+//! mutable reference even when you just have <code>[Pin]<[&mut] Self></code> (such as in your own
 //! [`poll`] implementation).
 //!
-//! [`Deref`]: crate::ops::Deref
-//! [`DerefMut`]: crate::ops::DerefMut
-//! [`mem::swap`]: crate::mem::swap
-//! [`mem::forget`]: crate::mem::forget
-//! [`Box<T>`]: ../../std/boxed/struct.Box.html
-//! [`Vec<T>`]: ../../std/vec/struct.Vec.html
-//! [`Vec::set_len`]: ../../std/vec/struct.Vec.html#method.set_len
-//! [`Box`]: ../../std/boxed/struct.Box.html
-//! [Vec::pop]: ../../std/vec/struct.Vec.html#method.pop
-//! [Vec::push]: ../../std/vec/struct.Vec.html#method.push
-//! [`Rc`]: ../../std/rc/struct.Rc.html
-//! [`RefCell<T>`]: crate::cell::RefCell
-//! [`drop`]: Drop::drop
-//! [`VecDeque<T>`]: ../../std/collections/struct.VecDeque.html
-//! [`Some(v)`]: Some
-//! [`ptr::write`]: crate::ptr::write
-//! [`Future`]: crate::future::Future
+//! [Deref]: crate::ops::Deref "ops::Deref"
+//! [`Deref`]: crate::ops::Deref "ops::Deref"
+//! [Target]: crate::ops::Deref::Target "ops::Deref::Target"
+//! [`DerefMut`]: crate::ops::DerefMut "ops::DerefMut"
+//! [`mem::swap`]: crate::mem::swap "mem::swap"
+//! [`mem::forget`]: crate::mem::forget "mem::forget"
+//! [Vec]: ../../std/vec/struct.Vec.html "Vec"
+//! [`Vec::set_len`]: ../../std/vec/struct.Vec.html#method.set_len "Vec::set_len"
+//! [Box]: ../../std/boxed/struct.Box.html "Box"
+//! [Vec::pop]: ../../std/vec/struct.Vec.html#method.pop "Vec::pop"
+//! [Vec::push]: ../../std/vec/struct.Vec.html#method.push "Vec::push"
+//! [Rc]: ../../std/rc/struct.Rc.html "rc::Rc"
+//! [RefCell]: crate::cell::RefCell "cell::RefCell"
+//! [`drop`]: Drop::drop "Drop::drop"
+//! [VecDeque]: ../../std/collections/struct.VecDeque.html "collections::VecDeque"
+//! [`ptr::write`]: crate::ptr::write "ptr::write"
+//! [`Future`]: crate::future::Future "future::Future"
 //! [drop-impl]: #drop-implementation
 //! [drop-guarantee]: #drop-guarantee
-//! [`poll`]: crate::future::Future::poll
+//! [`poll`]: crate::future::Future::poll "future::Future::poll"
+//! [&]: ../../std/primitive.reference.html "shared reference"
+//! [&mut]: ../../std/primitive.reference.html "mutable reference"
+//! [`unsafe`]: ../../std/keyword.unsafe.html "keyword unsafe"
 
 #![stable(feature = "pin", since = "1.33.0")]
 

diff --git a/library/core/src/prelude/v1.rs b/library/core/src/prelude/v1.rs
index 7d33ca8..c89fe57 100644
--- a/library/core/src/prelude/v1.rs
+++ b/library/core/src/prelude/v1.rs

@@ -67,7 +67,6 @@
     bench, global_allocator, test, test_case, RustcDecodable, RustcEncodable,
 };
 
-#[cfg(not(bootstrap))]
 #[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
 #[doc(no_inline)]
 pub use crate::macros::builtin::derive;
@@ -80,7 +79,6 @@
 #[doc(no_inline)]
 pub use crate::macros::builtin::cfg_accessible;
 
-#[cfg(not(bootstrap))]
 #[unstable(
     feature = "cfg_eval",
     issue = "82679",

diff --git a/library/core/src/ptr/const_ptr.rs b/library/core/src/ptr/const_ptr.rs
index b511466..b9b2ba9 100644
--- a/library/core/src/ptr/const_ptr.rs
+++ b/library/core/src/ptr/const_ptr.rs

@@ -51,7 +51,6 @@
     /// Decompose a (possibly wide) pointer into is address and metadata components.
     ///
     /// The pointer can be later reconstructed with [`from_raw_parts`].
-    #[cfg(not(bootstrap))]
     #[unstable(feature = "ptr_metadata", issue = "81513")]
     #[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
     #[inline]
@@ -184,8 +183,7 @@
     /// Behavior:
     ///
     /// * Both the starting and resulting pointer must be either in bounds or one
-    ///   byte past the end of the same allocated object. Note that in Rust,
-    ///   every (stack-allocated) variable is considered a separate allocated object.
+    ///   byte past the end of the same [allocated object].
     ///
     /// * The computed offset, **in bytes**, cannot overflow an `isize`.
     ///
@@ -210,6 +208,7 @@
     /// enables more aggressive compiler optimizations.
     ///
     /// [`wrapping_offset`]: #method.wrapping_offset
+    /// [allocated object]: crate::ptr#allocated-object
     ///
     /// # Examples
     ///
@@ -227,7 +226,7 @@
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
     #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
-    #[inline]
+    #[inline(always)]
     pub const unsafe fn offset(self, count: isize) -> *const T
     where
         T: Sized,
@@ -245,9 +244,8 @@
     ///
     /// This operation itself is always safe, but using the resulting pointer is not.
     ///
-    /// The resulting pointer remains attached to the same allocated object that `self` points to.
-    /// It may *not* be used to access a different allocated object. Note that in Rust, every
-    /// (stack-allocated) variable is considered a separate allocated object.
+    /// The resulting pointer "remembers" the [allocated object] that `self` points to; it may not
+    /// be used to read or write other allocated objects.
     ///
     /// In other words, `let z = x.wrapping_offset((y as isize) - (x as isize))` does *not* make `z`
     /// the same as `y` even if we assume `T` has size `1` and there is no overflow: `z` is still
@@ -265,10 +263,8 @@
     /// `x.wrapping_offset(o).wrapping_offset(o.wrapping_neg())` is always the same as `x`. In other
     /// words, leaving the allocated object and then re-entering it later is permitted.
     ///
-    /// If you need to cross object boundaries, cast the pointer to an integer and
-    /// do the arithmetic there.
-    ///
     /// [`offset`]: #method.offset
+    /// [allocated object]: crate::ptr#allocated-object
     ///
     /// # Examples
     ///
@@ -292,7 +288,7 @@
     #[stable(feature = "ptr_wrapping_offset", since = "1.16.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
     #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
-    #[inline]
+    #[inline(always)]
     pub const fn wrapping_offset(self, count: isize) -> *const T
     where
         T: Sized,
@@ -314,8 +310,7 @@
     /// Behavior:
     ///
     /// * Both the starting and other pointer must be either in bounds or one
-    ///   byte past the end of the same allocated object. Note that in Rust,
-    ///   every (stack-allocated) variable is considered a separate allocated object.
+    ///   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.)
@@ -345,6 +340,7 @@
     /// such large allocations either.)
     ///
     /// [`add`]: #method.add
+    /// [allocated object]: crate::ptr#allocated-object
     ///
     /// # Panics
     ///
@@ -468,8 +464,7 @@
     /// Behavior:
     ///
     /// * Both the starting and resulting pointer must be either in bounds or one
-    ///   byte past the end of the same allocated object. Note that in Rust,
-    ///   every (stack-allocated) variable is considered a separate allocated object.
+    ///   byte past the end of the same [allocated object].
     ///
     /// * The computed offset, **in bytes**, cannot overflow an `isize`.
     ///
@@ -494,6 +489,7 @@
     /// enables more aggressive compiler optimizations.
     ///
     /// [`wrapping_add`]: #method.wrapping_add
+    /// [allocated object]: crate::ptr#allocated-object
     ///
     /// # Examples
     ///
@@ -511,7 +507,7 @@
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
     #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
-    #[inline]
+    #[inline(always)]
     pub const unsafe fn add(self, count: usize) -> Self
     where
         T: Sized,
@@ -532,8 +528,7 @@
     /// Behavior:
     ///
     /// * Both the starting and resulting pointer must be either in bounds or one
-    ///   byte past the end of the same allocated object. Note that in Rust,
-    ///   every (stack-allocated) variable is considered a separate allocated object.
+    ///   byte past the end of the same [allocated object].
     ///
     /// * The computed offset cannot exceed `isize::MAX` **bytes**.
     ///
@@ -558,6 +553,7 @@
     /// enables more aggressive compiler optimizations.
     ///
     /// [`wrapping_sub`]: #method.wrapping_sub
+    /// [allocated object]: crate::ptr#allocated-object
     ///
     /// # Examples
     ///
@@ -594,9 +590,8 @@
     ///
     /// This operation itself is always safe, but using the resulting pointer is not.
     ///
-    /// The resulting pointer remains attached to the same allocated object that `self` points to.
-    /// It may *not* be used to access a different allocated object. Note that in Rust, every
-    /// (stack-allocated) variable is considered a separate allocated object.
+    /// The resulting pointer "remembers" the [allocated object] that `self` points to; it may not
+    /// be used to read or write other allocated objects.
     ///
     /// In other words, `let z = x.wrapping_add((y as usize) - (x as usize))` does *not* make `z`
     /// the same as `y` even if we assume `T` has size `1` and there is no overflow: `z` is still
@@ -614,10 +609,8 @@
     /// `x.wrapping_add(o).wrapping_sub(o)` is always the same as `x`. In other words, leaving the
     /// allocated object and then re-entering it later is permitted.
     ///
-    /// If you need to cross object boundaries, cast the pointer to an integer and
-    /// do the arithmetic there.
-    ///
     /// [`add`]: #method.add
+    /// [allocated object]: crate::ptr#allocated-object
     ///
     /// # Examples
     ///
@@ -641,7 +634,7 @@
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
     #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
-    #[inline]
+    #[inline(always)]
     pub const fn wrapping_add(self, count: usize) -> Self
     where
         T: Sized,
@@ -659,9 +652,8 @@
     ///
     /// This operation itself is always safe, but using the resulting pointer is not.
     ///
-    /// The resulting pointer remains attached to the same allocated object that `self` points to.
-    /// It may *not* be used to access a different allocated object. Note that in Rust, every
-    /// (stack-allocated) variable is considered a separate allocated object.
+    /// The resulting pointer "remembers" the [allocated object] that `self` points to; it may not
+    /// be used to read or write other allocated objects.
     ///
     /// In other words, `let z = x.wrapping_sub((x as usize) - (y as usize))` does *not* make `z`
     /// the same as `y` even if we assume `T` has size `1` and there is no overflow: `z` is still
@@ -679,10 +671,8 @@
     /// `x.wrapping_add(o).wrapping_sub(o)` is always the same as `x`. In other words, leaving the
     /// allocated object and then re-entering it later is permitted.
     ///
-    /// If you need to cross object boundaries, cast the pointer to an integer and
-    /// do the arithmetic there.
-    ///
     /// [`sub`]: #method.sub
+    /// [allocated object]: crate::ptr#allocated-object
     ///
     /// # Examples
     ///
@@ -734,7 +724,7 @@
     /// #![feature(set_ptr_value)]
     /// # use core::fmt::Debug;
     /// let arr: [i32; 3] = [1, 2, 3];
-    /// let mut ptr = &arr[0] as *const dyn Debug;
+    /// let mut ptr = arr.as_ptr() as *const dyn Debug;
     /// let thin = ptr as *const u8;
     /// unsafe {
     ///     ptr = ptr.set_ptr_value(thin.add(8));
@@ -924,13 +914,6 @@
     #[unstable(feature = "slice_ptr_len", issue = "71146")]
     #[rustc_const_unstable(feature = "const_slice_ptr_len", issue = "71146")]
     pub const fn len(self) -> usize {
-        #[cfg(bootstrap)]
-        {
-            // SAFETY: this is safe because `*const [T]` and `FatPtr<T>` have the same layout.
-            // Only `std` can make this guarantee.
-            unsafe { Repr { rust: self }.raw }.len
-        }
-        #[cfg(not(bootstrap))]
         metadata(self)
     }
 
@@ -997,7 +980,7 @@
     /// * The pointer must be [valid] for reads for `ptr.len() * mem::size_of::<T>()` many bytes,
     ///   and it must be properly aligned. This means in particular:
     ///
-    ///     * The entire memory range of this slice must be contained within a single allocated object!
+    ///     * The entire memory range of this slice must be contained within a single [allocated object]!
     ///       Slices can never span across multiple allocated objects.
     ///
     ///     * The pointer must be aligned even for zero-length slices. One
@@ -1019,6 +1002,7 @@
     /// See also [`slice::from_raw_parts`][].
     ///
     /// [valid]: crate::ptr#safety
+    /// [allocated object]: crate::ptr#allocated-object
     #[inline]
     #[unstable(feature = "ptr_as_uninit", issue = "75402")]
     pub unsafe fn as_uninit_slice<'a>(self) -> Option<&'a [MaybeUninit<T>]> {

diff --git a/library/core/src/ptr/mod.rs b/library/core/src/ptr/mod.rs
index fd24469..28044e0 100644
--- a/library/core/src/ptr/mod.rs
+++ b/library/core/src/ptr/mod.rs

@@ -55,6 +55,14 @@
 //! has size 0, i.e., even if memory is not actually touched. Consider using
 //! [`NonNull::dangling`] in such cases.
 //!
+//! ## Allocated object
+//!
+//! For several operations, such as [`offset`] or field projections (`expr.field`), the notion of an
+//! "allocated object" becomes relevant. An allocated object is a contiguous region of memory.
+//! Common examples of allocated objects include stack-allocated variables (each variable is a
+//! separate allocated object), heap allocations (each allocation created by the global allocator is
+//! a separate allocated object), and `static` variables.
+//!
 //! [aliasing]: ../../nomicon/aliasing.html
 //! [book]: ../../book/ch19-01-unsafe-rust.html#dereferencing-a-raw-pointer
 //! [ub]: ../../reference/behavior-considered-undefined.html
@@ -82,11 +90,8 @@
 #[doc(inline)]
 pub use crate::intrinsics::write_bytes;
 
-#[cfg(not(bootstrap))]
 mod metadata;
-#[cfg(not(bootstrap))]
 pub(crate) use metadata::PtrRepr;
-#[cfg(not(bootstrap))]
 #[unstable(feature = "ptr_metadata", issue = "81513")]
 pub use metadata::{from_raw_parts, from_raw_parts_mut, metadata, DynMetadata, Pointee, Thin};
 
@@ -205,7 +210,8 @@
 #[inline(always)]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_promotable]
-#[rustc_const_stable(feature = "const_ptr_null", since = "1.32.0")]
+#[rustc_const_stable(feature = "const_ptr_null", since = "1.24.0")]
+#[rustc_diagnostic_item = "ptr_null"]
 pub const fn null<T>() -> *const T {
     0 as *const T
 }
@@ -223,38 +229,12 @@
 #[inline(always)]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_promotable]
-#[rustc_const_stable(feature = "const_ptr_null", since = "1.32.0")]
+#[rustc_const_stable(feature = "const_ptr_null", since = "1.24.0")]
+#[rustc_diagnostic_item = "ptr_null_mut"]
 pub const fn null_mut<T>() -> *mut T {
     0 as *mut T
 }
 
-#[cfg(bootstrap)]
-#[repr(C)]
-pub(crate) union Repr<T> {
-    pub(crate) rust: *const [T],
-    rust_mut: *mut [T],
-    pub(crate) raw: FatPtr<T>,
-}
-
-#[cfg(bootstrap)]
-#[repr(C)]
-pub(crate) struct FatPtr<T> {
-    data: *const T,
-    pub(crate) len: usize,
-}
-
-#[cfg(bootstrap)]
-// Manual impl needed to avoid `T: Clone` bound.
-impl<T> Clone for FatPtr<T> {
-    fn clone(&self) -> Self {
-        *self
-    }
-}
-
-#[cfg(bootstrap)]
-// Manual impl needed to avoid `T: Copy` bound.
-impl<T> Copy for FatPtr<T> {}
-
 /// Forms a raw slice from a pointer and a length.
 ///
 /// The `len` argument is the number of **elements**, not the number of bytes.
@@ -279,14 +259,6 @@
 #[stable(feature = "slice_from_raw_parts", since = "1.42.0")]
 #[rustc_const_unstable(feature = "const_slice_from_raw_parts", issue = "67456")]
 pub const fn slice_from_raw_parts<T>(data: *const T, len: usize) -> *const [T] {
-    #[cfg(bootstrap)]
-    {
-        // SAFETY: Accessing the value from the `Repr` union is safe since *const [T]
-        // and FatPtr have the same memory layouts. Only std can make this
-        // guarantee.
-        unsafe { Repr { raw: FatPtr { data, len } }.rust }
-    }
-    #[cfg(not(bootstrap))]
     from_raw_parts(data.cast(), len)
 }
 
@@ -319,13 +291,6 @@
 #[stable(feature = "slice_from_raw_parts", since = "1.42.0")]
 #[rustc_const_unstable(feature = "const_slice_from_raw_parts", issue = "67456")]
 pub const fn slice_from_raw_parts_mut<T>(data: *mut T, len: usize) -> *mut [T] {
-    #[cfg(bootstrap)]
-    {
-        // SAFETY: Accessing the value from the `Repr` union is safe since *mut [T]
-        // and FatPtr have the same memory layouts
-        unsafe { Repr { raw: FatPtr { data, len } }.rust_mut }
-    }
-    #[cfg(not(bootstrap))]
     from_raw_parts_mut(data.cast(), len)
 }
 
@@ -464,19 +429,32 @@
 
 #[inline]
 pub(crate) unsafe fn swap_nonoverlapping_one<T>(x: *mut T, y: *mut T) {
-    // For types smaller than the block optimization below,
-    // just swap directly to avoid pessimizing codegen.
-    if mem::size_of::<T>() < 32 {
-        // SAFETY: the caller must guarantee that `x` and `y` are valid
-        // for writes, properly aligned, and non-overlapping.
-        unsafe {
-            let z = read(x);
-            copy_nonoverlapping(y, x, 1);
-            write(y, z);
+    // NOTE(eddyb) SPIR-V's Logical addressing model doesn't allow for arbitrary
+    // reinterpretation of values as (chunkable) byte arrays, and the loop in the
+    // block optimization in `swap_nonoverlapping_bytes` is hard to rewrite back
+    // into the (unoptimized) direct swapping implementation, so we disable it.
+    // FIXME(eddyb) the block optimization also prevents MIR optimizations from
+    // understanding `mem::replace`, `Option::take`, etc. - a better overall
+    // solution might be to make `swap_nonoverlapping` into an intrinsic, which
+    // a backend can choose to implement using the block optimization, or not.
+    #[cfg(not(target_arch = "spirv"))]
+    {
+        // Only apply the block optimization in `swap_nonoverlapping_bytes` for types
+        // at least as large as the block size, to avoid pessimizing codegen.
+        if mem::size_of::<T>() >= 32 {
+            // SAFETY: the caller must uphold the safety contract for `swap_nonoverlapping`.
+            unsafe { swap_nonoverlapping(x, y, 1) };
+            return;
         }
-    } else {
-        // SAFETY: the caller must uphold the safety contract for `swap_nonoverlapping`.
-        unsafe { swap_nonoverlapping(x, y, 1) };
+    }
+
+    // Direct swapping, for the cases not going through the block optimization.
+    // SAFETY: the caller must guarantee that `x` and `y` are valid
+    // for writes, properly aligned, and non-overlapping.
+    unsafe {
+        let z = read(x);
+        copy_nonoverlapping(y, x, 1);
+        write(y, z);
     }
 }
 
@@ -765,6 +743,7 @@
 ///     unaligned: 0x01020304,
 /// };
 ///
+/// #[allow(unaligned_references)]
 /// let v = unsafe {
 ///     // Here we attempt to take the address of a 32-bit integer which is not aligned.
 ///     let unaligned =
@@ -962,6 +941,7 @@
 /// let v = 0x01020304;
 /// let mut packed: Packed = unsafe { std::mem::zeroed() };
 ///
+/// #[allow(unaligned_references)]
 /// let v = unsafe {
 ///     // Here we attempt to take the address of a 32-bit integer which is not aligned.
 ///     let unaligned =
@@ -1516,6 +1496,10 @@
 /// as all other references. This macro can create a raw pointer *without* creating
 /// a reference first.
 ///
+/// Note, however, that the `expr` in `addr_of!(expr)` is still subject to all
+/// the usual rules. In particular, `addr_of!(*ptr::null())` is Undefined
+/// Behavior because it dereferences a NULL pointer.
+///
 /// # Example
 ///
 /// ```
@@ -1532,6 +1516,10 @@
 /// let raw_f2 = ptr::addr_of!(packed.f2);
 /// assert_eq!(unsafe { raw_f2.read_unaligned() }, 2);
 /// ```
+///
+/// See [`addr_of_mut`] for how to create a pointer to unininitialized data.
+/// Doing that with `addr_of` would not make much sense since one could only
+/// read the data, and that would be Undefined Behavior.
 #[stable(feature = "raw_ref_macros", since = "1.51.0")]
 #[rustc_macro_transparency = "semitransparent"]
 #[allow_internal_unstable(raw_ref_op)]
@@ -1548,7 +1536,13 @@
 /// as all other references. This macro can create a raw pointer *without* creating
 /// a reference first.
 ///
-/// # Example
+/// Note, however, that the `expr` in `addr_of_mut!(expr)` is still subject to all
+/// the usual rules. In particular, `addr_of_mut!(*ptr::null_mut())` is Undefined
+/// Behavior because it dereferences a NULL pointer.
+///
+/// # Examples
+///
+/// **Creating a pointer to unaligned data:**
 ///
 /// ```
 /// use std::ptr;
@@ -1565,6 +1559,23 @@
 /// unsafe { raw_f2.write_unaligned(42); }
 /// assert_eq!({packed.f2}, 42); // `{...}` forces copying the field instead of creating a reference.
 /// ```
+///
+/// **Creating a pointer to uninitialized data:**
+///
+/// ```rust
+/// use std::{ptr, mem::MaybeUninit};
+///
+/// struct Demo {
+///     field: bool,
+/// }
+///
+/// let mut uninit = MaybeUninit::<Demo>::uninit();
+/// // `&uninit.as_mut().field` would create a reference to an uninitialized `bool`,
+/// // and thus be Undefined Behavior!
+/// let f1_ptr = unsafe { ptr::addr_of_mut!((*uninit.as_mut_ptr()).field) };
+/// unsafe { f1_ptr.write(true); }
+/// let init = unsafe { uninit.assume_init() };
+/// ```
 #[stable(feature = "raw_ref_macros", since = "1.51.0")]
 #[rustc_macro_transparency = "semitransparent"]
 #[allow_internal_unstable(raw_ref_op)]

diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs
index a9de233..16f6efc 100644
--- a/library/core/src/ptr/mut_ptr.rs
+++ b/library/core/src/ptr/mut_ptr.rs

@@ -50,7 +50,6 @@
     /// Decompose a (possibly wide) pointer into is address and metadata components.
     ///
     /// The pointer can be later reconstructed with [`from_raw_parts_mut`].
-    #[cfg(not(bootstrap))]
     #[unstable(feature = "ptr_metadata", issue = "81513")]
     #[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
     #[inline]
@@ -189,8 +188,7 @@
     /// Behavior:
     ///
     /// * Both the starting and resulting pointer must be either in bounds or one
-    ///   byte past the end of the same allocated object. Note that in Rust,
-    ///   every (stack-allocated) variable is considered a separate allocated object.
+    ///   byte past the end of the same [allocated object].
     ///
     /// * The computed offset, **in bytes**, cannot overflow an `isize`.
     ///
@@ -215,6 +213,7 @@
     /// enables more aggressive compiler optimizations.
     ///
     /// [`wrapping_offset`]: #method.wrapping_offset
+    /// [allocated object]: crate::ptr#allocated-object
     ///
     /// # Examples
     ///
@@ -232,7 +231,7 @@
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
     #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
-    #[inline]
+    #[inline(always)]
     pub const unsafe fn offset(self, count: isize) -> *mut T
     where
         T: Sized,
@@ -251,9 +250,8 @@
     ///
     /// This operation itself is always safe, but using the resulting pointer is not.
     ///
-    /// The resulting pointer remains attached to the same allocated object that `self` points to.
-    /// It may *not* be used to access a different allocated object. Note that in Rust, every
-    /// (stack-allocated) variable is considered a separate allocated object.
+    /// The resulting pointer "remembers" the [allocated object] that `self` points to; it may not
+    /// be used to read or write other allocated objects.
     ///
     /// In other words, `let z = x.wrapping_offset((y as isize) - (x as isize))` does *not* make `z`
     /// the same as `y` even if we assume `T` has size `1` and there is no overflow: `z` is still
@@ -271,10 +269,8 @@
     /// `x.wrapping_offset(o).wrapping_offset(o.wrapping_neg())` is always the same as `x`. In other
     /// words, leaving the allocated object and then re-entering it later is permitted.
     ///
-    /// If you need to cross object boundaries, cast the pointer to an integer and
-    /// do the arithmetic there.
-    ///
     /// [`offset`]: #method.offset
+    /// [allocated object]: crate::ptr#allocated-object
     ///
     /// # Examples
     ///
@@ -298,7 +294,7 @@
     #[stable(feature = "ptr_wrapping_offset", since = "1.16.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
     #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
-    #[inline]
+    #[inline(always)]
     pub const fn wrapping_offset(self, count: isize) -> *mut T
     where
         T: Sized,
@@ -485,8 +481,7 @@
     /// Behavior:
     ///
     /// * Both the starting and other pointer must be either in bounds or one
-    ///   byte past the end of the same allocated object. Note that in Rust,
-    ///   every (stack-allocated) variable is considered a separate allocated object.
+    ///   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.)
@@ -516,6 +511,7 @@
     /// such large allocations either.)
     ///
     /// [`add`]: #method.add
+    /// [allocated object]: crate::ptr#allocated-object
     ///
     /// # Panics
     ///
@@ -575,8 +571,7 @@
     /// Behavior:
     ///
     /// * Both the starting and resulting pointer must be either in bounds or one
-    ///   byte past the end of the same allocated object. Note that in Rust,
-    ///   every (stack-allocated) variable is considered a separate allocated object.
+    ///   byte past the end of the same [allocated object].
     ///
     /// * The computed offset, **in bytes**, cannot overflow an `isize`.
     ///
@@ -618,7 +613,7 @@
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
     #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
-    #[inline]
+    #[inline(always)]
     pub const unsafe fn add(self, count: usize) -> Self
     where
         T: Sized,
@@ -639,8 +634,7 @@
     /// Behavior:
     ///
     /// * Both the starting and resulting pointer must be either in bounds or one
-    ///   byte past the end of the same allocated object. Note that in Rust,
-    ///   every (stack-allocated) variable is considered a separate allocated object.
+    ///   byte past the end of the same [allocated object].
     ///
     /// * The computed offset cannot exceed `isize::MAX` **bytes**.
     ///
@@ -665,6 +659,7 @@
     /// enables more aggressive compiler optimizations.
     ///
     /// [`wrapping_sub`]: #method.wrapping_sub
+    /// [allocated object]: crate::ptr#allocated-object
     ///
     /// # Examples
     ///
@@ -701,9 +696,8 @@
     ///
     /// This operation itself is always safe, but using the resulting pointer is not.
     ///
-    /// The resulting pointer remains attached to the same allocated object that `self` points to.
-    /// It may *not* be used to access a different allocated object. Note that in Rust, every
-    /// (stack-allocated) variable is considered a separate allocated object.
+    /// The resulting pointer "remembers" the [allocated object] that `self` points to; it may not
+    /// be used to read or write other allocated objects.
     ///
     /// In other words, `let z = x.wrapping_add((y as usize) - (x as usize))` does *not* make `z`
     /// the same as `y` even if we assume `T` has size `1` and there is no overflow: `z` is still
@@ -721,10 +715,8 @@
     /// `x.wrapping_add(o).wrapping_sub(o)` is always the same as `x`. In other words, leaving the
     /// allocated object and then re-entering it later is permitted.
     ///
-    /// If you need to cross object boundaries, cast the pointer to an integer and
-    /// do the arithmetic there.
-    ///
     /// [`add`]: #method.add
+    /// [allocated object]: crate::ptr#allocated-object
     ///
     /// # Examples
     ///
@@ -748,7 +740,7 @@
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
     #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
-    #[inline]
+    #[inline(always)]
     pub const fn wrapping_add(self, count: usize) -> Self
     where
         T: Sized,
@@ -766,9 +758,8 @@
     ///
     /// This operation itself is always safe, but using the resulting pointer is not.
     ///
-    /// The resulting pointer remains attached to the same allocated object that `self` points to.
-    /// It may *not* be used to access a different allocated object. Note that in Rust, every
-    /// (stack-allocated) variable is considered a separate allocated object.
+    /// The resulting pointer "remembers" the [allocated object] that `self` points to; it may not
+    /// be used to read or write other allocated objects.
     ///
     /// In other words, `let z = x.wrapping_sub((x as usize) - (y as usize))` does *not* make `z`
     /// the same as `y` even if we assume `T` has size `1` and there is no overflow: `z` is still
@@ -786,10 +777,8 @@
     /// `x.wrapping_add(o).wrapping_sub(o)` is always the same as `x`. In other words, leaving the
     /// allocated object and then re-entering it later is permitted.
     ///
-    /// If you need to cross object boundaries, cast the pointer to an integer and
-    /// do the arithmetic there.
-    ///
     /// [`sub`]: #method.sub
+    /// [allocated object]: crate::ptr#allocated-object
     ///
     /// # Examples
     ///
@@ -841,7 +830,7 @@
     /// #![feature(set_ptr_value)]
     /// # use core::fmt::Debug;
     /// let mut arr: [i32; 3] = [1, 2, 3];
-    /// let mut ptr = &mut arr[0] as *mut dyn Debug;
+    /// let mut ptr = arr.as_mut_ptr() as *mut dyn Debug;
     /// let thin = ptr as *mut u8;
     /// unsafe {
     ///     ptr = ptr.set_ptr_value(thin.add(8));
@@ -1184,13 +1173,6 @@
     #[unstable(feature = "slice_ptr_len", issue = "71146")]
     #[rustc_const_unstable(feature = "const_slice_ptr_len", issue = "71146")]
     pub const fn len(self) -> usize {
-        #[cfg(bootstrap)]
-        {
-            // SAFETY: this is safe because `*const [T]` and `FatPtr<T>` have the same layout.
-            // Only `std` can make this guarantee.
-            unsafe { Repr { rust_mut: self }.raw }.len
-        }
-        #[cfg(not(bootstrap))]
         metadata(self)
     }
 
@@ -1260,7 +1242,7 @@
     /// * The pointer must be [valid] for reads for `ptr.len() * mem::size_of::<T>()` many bytes,
     ///   and it must be properly aligned. This means in particular:
     ///
-    ///     * The entire memory range of this slice must be contained within a single allocated object!
+    ///     * The entire memory range of this slice must be contained within a single [allocated object]!
     ///       Slices can never span across multiple allocated objects.
     ///
     ///     * The pointer must be aligned even for zero-length slices. One
@@ -1282,6 +1264,7 @@
     /// See also [`slice::from_raw_parts`][].
     ///
     /// [valid]: crate::ptr#safety
+    /// [allocated object]: crate::ptr#allocated-object
     #[inline]
     #[unstable(feature = "ptr_as_uninit", issue = "75402")]
     pub unsafe fn as_uninit_slice<'a>(self) -> Option<&'a [MaybeUninit<T>]> {
@@ -1310,7 +1293,7 @@
     /// * The pointer must be [valid] for reads and writes for `ptr.len() * mem::size_of::<T>()`
     ///   many bytes, and it must be properly aligned. This means in particular:
     ///
-    ///     * The entire memory range of this slice must be contained within a single allocated object!
+    ///     * The entire memory range of this slice must be contained within a single [allocated object]!
     ///       Slices can never span across multiple allocated objects.
     ///
     ///     * The pointer must be aligned even for zero-length slices. One
@@ -1332,6 +1315,7 @@
     /// See also [`slice::from_raw_parts_mut`][].
     ///
     /// [valid]: crate::ptr#safety
+    /// [allocated object]: crate::ptr#allocated-object
     #[inline]
     #[unstable(feature = "ptr_as_uninit", issue = "75402")]
     pub unsafe fn as_uninit_slice_mut<'a>(self) -> Option<&'a mut [MaybeUninit<T>]> {

diff --git a/library/core/src/ptr/non_null.rs b/library/core/src/ptr/non_null.rs
index 8d533cd..e525f61 100644
--- a/library/core/src/ptr/non_null.rs
+++ b/library/core/src/ptr/non_null.rs

@@ -72,7 +72,7 @@
     /// sentinel value. Types that lazily allocate must track initialization by
     /// some other means.
     #[stable(feature = "nonnull", since = "1.25.0")]
-    #[rustc_const_stable(feature = "const_nonnull_dangling", since = "1.32.0")]
+    #[rustc_const_stable(feature = "const_nonnull_dangling", since = "1.36.0")]
     #[inline]
     pub const fn dangling() -> Self {
         // SAFETY: mem::align_of() returns a non-zero usize which is then casted
@@ -110,7 +110,7 @@
     /// [the module documentation]: crate::ptr#safety
     #[inline]
     #[unstable(feature = "ptr_as_uninit", issue = "75402")]
-    pub unsafe fn as_uninit_ref(&self) -> &MaybeUninit<T> {
+    pub 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() }
@@ -142,7 +142,7 @@
     /// [the module documentation]: crate::ptr#safety
     #[inline]
     #[unstable(feature = "ptr_as_uninit", issue = "75402")]
-    pub unsafe fn as_uninit_mut(&mut self) -> &mut MaybeUninit<T> {
+    pub unsafe fn as_uninit_mut<'a>(&mut 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() }
@@ -156,7 +156,7 @@
     ///
     /// `ptr` must be non-null.
     #[stable(feature = "nonnull", since = "1.25.0")]
-    #[rustc_const_stable(feature = "const_nonnull_new_unchecked", since = "1.32.0")]
+    #[rustc_const_stable(feature = "const_nonnull_new_unchecked", since = "1.25.0")]
     #[inline]
     pub const unsafe fn new_unchecked(ptr: *mut T) -> Self {
         // SAFETY: the caller must guarantee that `ptr` is non-null.
@@ -181,7 +181,6 @@
     /// See the documentation of [`std::ptr::from_raw_parts`] for more details.
     ///
     /// [`std::ptr::from_raw_parts`]: crate::ptr::from_raw_parts
-    #[cfg(not(bootstrap))]
     #[unstable(feature = "ptr_metadata", issue = "81513")]
     #[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
     #[inline]
@@ -198,7 +197,6 @@
     /// Decompose a (possibly wide) pointer into is address and metadata components.
     ///
     /// The pointer can be later reconstructed with [`NonNull::from_raw_parts`].
-    #[cfg(not(bootstrap))]
     #[unstable(feature = "ptr_metadata", issue = "81513")]
     #[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
     #[inline]
@@ -244,7 +242,7 @@
     /// [the module documentation]: crate::ptr#safety
     #[stable(feature = "nonnull", since = "1.25.0")]
     #[inline]
-    pub unsafe fn as_ref(&self) -> &T {
+    pub unsafe fn as_ref<'a>(&self) -> &'a T {
         // SAFETY: the caller must guarantee that `self` meets all the
         // requirements for a reference.
         unsafe { &*self.as_ptr() }
@@ -280,7 +278,7 @@
     /// [the module documentation]: crate::ptr#safety
     #[stable(feature = "nonnull", since = "1.25.0")]
     #[inline]
-    pub unsafe fn as_mut(&mut self) -> &mut T {
+    pub unsafe fn as_mut<'a>(&mut self) -> &'a mut T {
         // SAFETY: the caller must guarantee that `self` meets all the
         // requirements for a mutable reference.
         unsafe { &mut *self.as_ptr() }
@@ -288,7 +286,7 @@
 
     /// Casts to a pointer of another type.
     #[stable(feature = "nonnull_cast", since = "1.27.0")]
-    #[rustc_const_stable(feature = "const_nonnull_cast", since = "1.32.0")]
+    #[rustc_const_stable(feature = "const_nonnull_cast", since = "1.36.0")]
     #[inline]
     pub const fn cast<U>(self) -> NonNull<U> {
         // SAFETY: `self` is a `NonNull` pointer which is necessarily non-null
@@ -427,7 +425,7 @@
     /// [valid]: crate::ptr#safety
     #[inline]
     #[unstable(feature = "ptr_as_uninit", issue = "75402")]
-    pub unsafe fn as_uninit_slice(&self) -> &[MaybeUninit<T>] {
+    pub 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()) }
     }
@@ -488,7 +486,7 @@
     /// ```
     #[inline]
     #[unstable(feature = "ptr_as_uninit", issue = "75402")]
-    pub unsafe fn as_uninit_slice_mut(&self) -> &mut [MaybeUninit<T>] {
+    pub 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()) }
     }

diff --git a/library/core/src/raw.rs b/library/core/src/raw.rs
index 1227d9b..6d1e28f 100644
--- a/library/core/src/raw.rs
+++ b/library/core/src/raw.rs

@@ -1,5 +1,9 @@
 #![allow(missing_docs)]
 #![unstable(feature = "raw", issue = "27751")]
+#![rustc_deprecated(
+    since = "1.53.0",
+    reason = "use pointer metadata APIs instead https://github.com/rust-lang/rust/issues/81513"
+)]
 
 //! Contains struct definitions for the layout of compiler built-in types.
 //!

diff --git a/library/core/src/result.rs b/library/core/src/result.rs
index 2ce8a70..e0071f8 100644
--- a/library/core/src/result.rs
+++ b/library/core/src/result.rs

@@ -228,7 +228,7 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use crate::iter::{self, FromIterator, FusedIterator, TrustedLen};
-use crate::ops::{self, Deref, DerefMut};
+use crate::ops::{self, ControlFlow, Deref, DerefMut};
 use crate::{convert, fmt, hint};
 
 /// `Result` is a type that represents either success ([`Ok`]) or failure ([`Err`]).
@@ -506,8 +506,8 @@
         }
     }
 
-    /// Applies a function to the contained value (if [`Ok`]),
-    /// or returns the provided default (if [`Err`]).
+    /// Returns the provided default (if [`Err`]), or
+    /// applies a function to the contained value (if [`Ok`]),
     ///
     /// Arguments passed to `map_or` are eagerly evaluated; if you are passing
     /// the result of a function call, it is recommended to use [`map_or_else`],
@@ -533,9 +533,9 @@
         }
     }
 
-    /// Maps a `Result<T, E>` to `U` by applying a function to a
-    /// contained [`Ok`] value, or a fallback function to a
-    /// contained [`Err`] value.
+    /// Maps a `Result<T, E>` to `U` by applying a fallback function to a
+    /// contained [`Err`] value, or a default function to a
+    /// contained [`Ok`] value.
     ///
     /// This function can be used to unpack a successful result
     /// while handling an error.
@@ -1167,6 +1167,42 @@
     }
 }
 
+#[unstable(feature = "unwrap_infallible", reason = "newly added", issue = "61695")]
+impl<T: Into<!>, E> Result<T, E> {
+    /// Returns the contained [`Err`] value, but never panics.
+    ///
+    /// Unlike [`unwrap_err`], this method is known to never panic on the
+    /// result types it is implemented for. Therefore, it can be used
+    /// instead of `unwrap_err` as a maintainability safeguard that will fail
+    /// to compile if the ok type of the `Result` is later changed
+    /// to a type that can actually occur.
+    ///
+    /// [`unwrap_err`]: Result::unwrap_err
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// # #![feature(never_type)]
+    /// # #![feature(unwrap_infallible)]
+    ///
+    /// fn only_bad_news() -> Result<!, String> {
+    ///     Err("Oops, it failed".into())
+    /// }
+    ///
+    /// let error: String = only_bad_news().into_err();
+    /// println!("{}", error);
+    /// ```
+    #[inline]
+    pub fn into_err(self) -> E {
+        match self {
+            Ok(x) => x.into(),
+            Err(e) => e,
+        }
+    }
+}
+
 impl<T: Deref, E> Result<T, E> {
     /// Converts from `Result<T, E>` (or `&Result<T, E>`) to `Result<&<T as Deref>::Target, &E>`.
     ///
@@ -1610,3 +1646,32 @@
         Err(v)
     }
 }
+
+#[unstable(feature = "try_trait_v2", issue = "84277")]
+impl<T, E> ops::TryV2 for Result<T, E> {
+    type Output = T;
+    type Residual = Result<convert::Infallible, E>;
+
+    #[inline]
+    fn from_output(output: Self::Output) -> Self {
+        Ok(output)
+    }
+
+    #[inline]
+    fn branch(self) -> ControlFlow<Self::Residual, Self::Output> {
+        match self {
+            Ok(v) => ControlFlow::Continue(v),
+            Err(e) => ControlFlow::Break(Err(e)),
+        }
+    }
+}
+
+#[unstable(feature = "try_trait_v2", issue = "84277")]
+impl<T, E, F: From<E>> ops::FromResidual<Result<convert::Infallible, E>> for Result<T, F> {
+    #[inline]
+    fn from_residual(residual: Result<convert::Infallible, E>) -> Self {
+        match residual {
+            Err(e) => Err(From::from(e)),
+        }
+    }
+}

diff --git a/library/core/src/slice/ascii.rs b/library/core/src/slice/ascii.rs
index 42032bc..906dcb1 100644
--- a/library/core/src/slice/ascii.rs
+++ b/library/core/src/slice/ascii.rs

@@ -1,6 +1,10 @@
 //! Operations on ASCII `[u8]`.
 
+use crate::ascii;
+use crate::fmt::{self, Write};
+use crate::iter;
 use crate::mem;
+use crate::ops;
 
 #[lang = "slice_u8"]
 #[cfg(not(test))]
@@ -19,7 +23,7 @@
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool {
-        self.len() == other.len() && self.iter().zip(other).all(|(a, b)| a.eq_ignore_ascii_case(b))
+        self.len() == other.len() && iter::zip(self, other).all(|(a, b)| a.eq_ignore_ascii_case(b))
     }
 
     /// Converts this slice to its ASCII upper case equivalent in-place.
@@ -55,6 +59,95 @@
             byte.make_ascii_lowercase();
         }
     }
+
+    /// Returns an iterator that produces an escaped version of this slice,
+    /// treating it as an ASCII string.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(inherent_ascii_escape)]
+    ///
+    /// let s = b"0\t\r\n'\"\\\x9d";
+    /// let escaped = s.escape_ascii().to_string();
+    /// assert_eq!(escaped, "0\\t\\r\\n\\'\\\"\\\\\\x9d");
+    /// ```
+    #[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+    pub fn escape_ascii(&self) -> EscapeAscii<'_> {
+        EscapeAscii { inner: self.iter().flat_map(EscapeByte) }
+    }
+}
+
+impl_fn_for_zst! {
+    #[derive(Clone)]
+    struct EscapeByte impl Fn = |byte: &u8| -> ascii::EscapeDefault {
+        ascii::escape_default(*byte)
+    };
+}
+
+/// An iterator over the escaped version of a byte slice.
+///
+/// This `struct` is created by the [`slice::escape_ascii`] method. See its
+/// documentation for more information.
+#[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+#[derive(Clone)]
+pub struct EscapeAscii<'a> {
+    inner: iter::FlatMap<super::Iter<'a, u8>, ascii::EscapeDefault, EscapeByte>,
+}
+
+#[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+impl<'a> iter::Iterator for EscapeAscii<'a> {
+    type Item = u8;
+    #[inline]
+    fn next(&mut self) -> Option<u8> {
+        self.inner.next()
+    }
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
+    #[inline]
+    fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R
+    where
+        Fold: FnMut(Acc, Self::Item) -> R,
+        R: ops::Try<Ok = Acc>,
+    {
+        self.inner.try_fold(init, fold)
+    }
+    #[inline]
+    fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc
+    where
+        Fold: FnMut(Acc, Self::Item) -> Acc,
+    {
+        self.inner.fold(init, fold)
+    }
+    #[inline]
+    fn last(mut self) -> Option<u8> {
+        self.next_back()
+    }
+}
+
+#[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+impl<'a> iter::DoubleEndedIterator for EscapeAscii<'a> {
+    fn next_back(&mut self) -> Option<u8> {
+        self.inner.next_back()
+    }
+}
+#[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+impl<'a> iter::ExactSizeIterator for EscapeAscii<'a> {}
+#[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+impl<'a> iter::FusedIterator for EscapeAscii<'a> {}
+#[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+impl<'a> fmt::Display for EscapeAscii<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.clone().try_for_each(|b| f.write_char(b as char))
+    }
+}
+#[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+impl<'a> fmt::Debug for EscapeAscii<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("EscapeAscii").finish_non_exhaustive()
+    }
 }
 
 /// Returns `true` if any byte in the word `v` is nonascii (>= 128). Snarfed

diff --git a/library/core/src/slice/index.rs b/library/core/src/slice/index.rs
index c92b37b..f722430 100644
--- a/library/core/src/slice/index.rs
+++ b/library/core/src/slice/index.rs

@@ -81,6 +81,8 @@
     impl Sealed for ops::RangeInclusive<usize> {}
     #[stable(feature = "slice_get_slice", since = "1.28.0")]
     impl Sealed for ops::RangeToInclusive<usize> {}
+    #[stable(feature = "slice_index_with_ops_bound_pair", since = "1.53.0")]
+    impl Sealed for (ops::Bound<usize>, ops::Bound<usize>) {}
 }
 
 /// A helper trait used for indexing operations.
@@ -546,3 +548,113 @@
 
     ops::Range { start, end }
 }
+
+/// Convert pair of `ops::Bound`s into `ops::Range` without performing any bounds checking and (in debug) overflow checking
+fn into_range_unchecked(
+    len: usize,
+    (start, end): (ops::Bound<usize>, ops::Bound<usize>),
+) -> ops::Range<usize> {
+    use ops::Bound;
+    let start = match start {
+        Bound::Included(i) => i,
+        Bound::Excluded(i) => i + 1,
+        Bound::Unbounded => 0,
+    };
+    let end = match end {
+        Bound::Included(i) => i + 1,
+        Bound::Excluded(i) => i,
+        Bound::Unbounded => len,
+    };
+    start..end
+}
+
+/// Convert pair of `ops::Bound`s into `ops::Range`.
+/// Returns `None` on overflowing indices.
+fn into_range(
+    len: usize,
+    (start, end): (ops::Bound<usize>, ops::Bound<usize>),
+) -> Option<ops::Range<usize>> {
+    use ops::Bound;
+    let start = match start {
+        Bound::Included(start) => start,
+        Bound::Excluded(start) => start.checked_add(1)?,
+        Bound::Unbounded => 0,
+    };
+
+    let end = match end {
+        Bound::Included(end) => end.checked_add(1)?,
+        Bound::Excluded(end) => end,
+        Bound::Unbounded => len,
+    };
+
+    // Don't bother with checking `start < end` and `end <= len`
+    // since these checks are handled by `Range` impls
+
+    Some(start..end)
+}
+
+/// Convert pair of `ops::Bound`s into `ops::Range`.
+/// Panics on overflowing indices.
+fn into_slice_range(
+    len: usize,
+    (start, end): (ops::Bound<usize>, ops::Bound<usize>),
+) -> ops::Range<usize> {
+    use ops::Bound;
+    let start = match start {
+        Bound::Included(start) => start,
+        Bound::Excluded(start) => {
+            start.checked_add(1).unwrap_or_else(|| slice_start_index_overflow_fail())
+        }
+        Bound::Unbounded => 0,
+    };
+
+    let end = match end {
+        Bound::Included(end) => {
+            end.checked_add(1).unwrap_or_else(|| slice_end_index_overflow_fail())
+        }
+        Bound::Excluded(end) => end,
+        Bound::Unbounded => len,
+    };
+
+    // Don't bother with checking `start < end` and `end <= len`
+    // since these checks are handled by `Range` impls
+
+    start..end
+}
+
+#[stable(feature = "slice_index_with_ops_bound_pair", since = "1.53.0")]
+unsafe impl<T> SliceIndex<[T]> for (ops::Bound<usize>, ops::Bound<usize>) {
+    type Output = [T];
+
+    #[inline]
+    fn get(self, slice: &[T]) -> Option<&Self::Output> {
+        into_range(slice.len(), self)?.get(slice)
+    }
+
+    #[inline]
+    fn get_mut(self, slice: &mut [T]) -> Option<&mut Self::Output> {
+        into_range(slice.len(), self)?.get_mut(slice)
+    }
+
+    #[inline]
+    unsafe fn get_unchecked(self, slice: *const [T]) -> *const Self::Output {
+        // SAFETY: the caller has to uphold the safety contract for `get_unchecked`.
+        unsafe { into_range_unchecked(slice.len(), self).get_unchecked(slice) }
+    }
+
+    #[inline]
+    unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut Self::Output {
+        // SAFETY: the caller has to uphold the safety contract for `get_unchecked_mut`.
+        unsafe { into_range_unchecked(slice.len(), self).get_unchecked_mut(slice) }
+    }
+
+    #[inline]
+    fn index(self, slice: &[T]) -> &Self::Output {
+        into_slice_range(slice.len(), self).index(slice)
+    }
+
+    #[inline]
+    fn index_mut(self, slice: &mut [T]) -> &mut Self::Output {
+        into_slice_range(slice.len(), self).index_mut(slice)
+    }
+}

diff --git a/library/core/src/slice/iter.rs b/library/core/src/slice/iter.rs
index c82b76d..1ee662c 100644
--- a/library/core/src/slice/iter.rs
+++ b/library/core/src/slice/iter.rs

@@ -286,7 +286,6 @@
     /// Basic usage:
     ///
     /// ```
-    /// # #![feature(slice_iter_mut_as_slice)]
     /// let mut slice: &mut [usize] = &mut [1, 2, 3];
     ///
     /// // First, we get the iterator:
@@ -299,12 +298,19 @@
     /// // Now `as_slice` returns "[2, 3]":
     /// assert_eq!(iter.as_slice(), &[2, 3]);
     /// ```
-    #[unstable(feature = "slice_iter_mut_as_slice", reason = "recently added", issue = "58957")]
+    #[stable(feature = "slice_iter_mut_as_slice", since = "1.53.0")]
     pub fn as_slice(&self) -> &[T] {
         self.make_slice()
     }
 }
 
+#[stable(feature = "slice_iter_mut_as_slice", since = "1.53.0")]
+impl<T> AsRef<[T]> for IterMut<'_, T> {
+    fn as_ref(&self) -> &[T] {
+        self.as_slice()
+    }
+}
+
 iterator! {struct IterMut -> *mut T, &'a mut T, mut, {mut}, {}}
 
 /// An internal abstraction over the splitting iterators, so that

diff --git a/library/core/src/slice/mod.rs b/library/core/src/slice/mod.rs
index 417a106..ec28cdd 100644
--- a/library/core/src/slice/mod.rs
+++ b/library/core/src/slice/mod.rs

@@ -81,6 +81,9 @@
 #[unstable(feature = "slice_range", issue = "76393")]
 pub use index::range;
 
+#[unstable(feature = "inherent_ascii_escape", issue = "77174")]
+pub use ascii::EscapeAscii;
+
 #[lang = "slice"]
 #[cfg(not(test))]
 impl<T> [T] {
@@ -94,28 +97,19 @@
     /// ```
     #[doc(alias = "length")]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_slice_len", since = "1.32.0")]
+    #[rustc_const_stable(feature = "const_slice_len", since = "1.39.0")]
     #[inline]
     // SAFETY: const sound because we transmute out the length field as a usize (which it must be)
     #[rustc_allow_const_fn_unstable(const_fn_union)]
     pub const fn len(&self) -> usize {
-        #[cfg(bootstrap)]
-        {
-            // SAFETY: this is safe because `&[T]` and `FatPtr<T>` have the same layout.
-            // Only `std` can make this guarantee.
-            unsafe { crate::ptr::Repr { rust: self }.raw.len }
-        }
-        #[cfg(not(bootstrap))]
-        {
-            // FIXME: Replace with `crate::ptr::metadata(self)` when that is const-stable.
-            // As of this writing this causes a "Const-stable functions can only call other
-            // const-stable functions" error.
+        // FIXME: Replace with `crate::ptr::metadata(self)` when that is const-stable.
+        // As of this writing this causes a "Const-stable functions can only call other
+        // const-stable functions" error.
 
-            // SAFETY: Accessing the value from the `PtrRepr` union is safe since *const T
-            // and PtrComponents<T> have the same memory layouts. Only std can make this
-            // guarantee.
-            unsafe { crate::ptr::PtrRepr { const_ptr: self }.components.metadata }
-        }
+        // SAFETY: Accessing the value from the `PtrRepr` union is safe since *const T
+        // and PtrComponents<T> have the same memory layouts. Only std can make this
+        // guarantee.
+        unsafe { crate::ptr::PtrRepr { const_ptr: self }.components.metadata }
     }
 
     /// Returns `true` if the slice has a length of 0.
@@ -127,7 +121,7 @@
     /// assert!(!a.is_empty());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_slice_is_empty", since = "1.32.0")]
+    #[rustc_const_stable(feature = "const_slice_is_empty", since = "1.39.0")]
     #[inline]
     pub const fn is_empty(&self) -> bool {
         self.len() == 0
@@ -145,8 +139,9 @@
     /// assert_eq!(None, w.first());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_slice_first_last", issue = "83570")]
     #[inline]
-    pub fn first(&self) -> Option<&T> {
+    pub const fn first(&self) -> Option<&T> {
         if let [first, ..] = self { Some(first) } else { None }
     }
 
@@ -163,8 +158,9 @@
     /// assert_eq!(x, &[5, 1, 2]);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_slice_first_last", issue = "83570")]
     #[inline]
-    pub fn first_mut(&mut self) -> Option<&mut T> {
+    pub const fn first_mut(&mut self) -> Option<&mut T> {
         if let [first, ..] = self { Some(first) } else { None }
     }
 
@@ -181,8 +177,9 @@
     /// }
     /// ```
     #[stable(feature = "slice_splits", since = "1.5.0")]
+    #[rustc_const_unstable(feature = "const_slice_first_last", issue = "83570")]
     #[inline]
-    pub fn split_first(&self) -> Option<(&T, &[T])> {
+    pub const fn split_first(&self) -> Option<(&T, &[T])> {
         if let [first, tail @ ..] = self { Some((first, tail)) } else { None }
     }
 
@@ -201,8 +198,9 @@
     /// assert_eq!(x, &[3, 4, 5]);
     /// ```
     #[stable(feature = "slice_splits", since = "1.5.0")]
+    #[rustc_const_unstable(feature = "const_slice_first_last", issue = "83570")]
     #[inline]
-    pub fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])> {
+    pub const fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])> {
         if let [first, tail @ ..] = self { Some((first, tail)) } else { None }
     }
 
@@ -219,8 +217,9 @@
     /// }
     /// ```
     #[stable(feature = "slice_splits", since = "1.5.0")]
+    #[rustc_const_unstable(feature = "const_slice_first_last", issue = "83570")]
     #[inline]
-    pub fn split_last(&self) -> Option<(&T, &[T])> {
+    pub const fn split_last(&self) -> Option<(&T, &[T])> {
         if let [init @ .., last] = self { Some((last, init)) } else { None }
     }
 
@@ -239,8 +238,9 @@
     /// assert_eq!(x, &[4, 5, 3]);
     /// ```
     #[stable(feature = "slice_splits", since = "1.5.0")]
+    #[rustc_const_unstable(feature = "const_slice_first_last", issue = "83570")]
     #[inline]
-    pub fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])> {
+    pub const fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])> {
         if let [init @ .., last] = self { Some((last, init)) } else { None }
     }
 
@@ -256,8 +256,9 @@
     /// assert_eq!(None, w.last());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_slice_first_last", issue = "83570")]
     #[inline]
-    pub fn last(&self) -> Option<&T> {
+    pub const fn last(&self) -> Option<&T> {
         if let [.., last] = self { Some(last) } else { None }
     }
 
@@ -274,8 +275,9 @@
     /// assert_eq!(x, &[0, 1, 10]);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_slice_first_last", issue = "83570")]
     #[inline]
-    pub fn last_mut(&mut self) -> Option<&mut T> {
+    pub const fn last_mut(&mut self) -> Option<&mut T> {
         if let [.., last] = self { Some(last) } else { None }
     }
 
@@ -2204,6 +2206,8 @@
             } else if cmp == Greater {
                 right = mid;
             } else {
+                // SAFETY: same as the `get_unchecked` above
+                unsafe { crate::intrinsics::assume(mid < self.len()) };
                 return Ok(mid);
             }
 
@@ -2252,8 +2256,7 @@
     // in crate `alloc`, and as such doesn't exists yet when building `core`.
     // links to downstream crate: #74481. Since primitives are only documented in
     // libstd (#73423), this never leads to broken links in practice.
-    #[cfg_attr(not(bootstrap), allow(rustdoc::broken_intra_doc_links))]
-    #[cfg_attr(bootstrap, allow(broken_intra_doc_links))]
+    #[allow(rustdoc::broken_intra_doc_links)]
     #[stable(feature = "slice_binary_search_by_key", since = "1.10.0")]
     #[inline]
     pub fn binary_search_by_key<'a, B, F>(&'a self, b: &B, mut f: F) -> Result<usize, usize>

diff --git a/library/core/src/slice/specialize.rs b/library/core/src/slice/specialize.rs
index 16a9588..425cf71 100644
--- a/library/core/src/slice/specialize.rs
+++ b/library/core/src/slice/specialize.rs

@@ -1,3 +1,4 @@
+use crate::mem::{size_of, transmute_copy};
 use crate::ptr::write_bytes;
 
 pub(super) trait SpecFill<T> {
@@ -17,42 +18,18 @@
 }
 
 impl<T: Copy> SpecFill<T> for [T] {
-    default fn spec_fill(&mut self, value: T) {
-        for item in self.iter_mut() {
-            *item = value;
-        }
-    }
-}
-
-impl SpecFill<u8> for [u8] {
-    fn spec_fill(&mut self, value: u8) {
-        // SAFETY: this is slice of u8
-        unsafe {
-            let ptr = self.as_mut_ptr();
-            let len = self.len();
-            write_bytes(ptr, value, len);
-        }
-    }
-}
-
-impl SpecFill<i8> for [i8] {
-    fn spec_fill(&mut self, value: i8) {
-        // SAFETY: this is slice of i8
-        unsafe {
-            let ptr = self.as_mut_ptr();
-            let len = self.len();
-            write_bytes(ptr, value as u8, len);
-        }
-    }
-}
-
-impl SpecFill<bool> for [bool] {
-    fn spec_fill(&mut self, value: bool) {
-        // SAFETY: this is slice of bool
-        unsafe {
-            let ptr = self.as_mut_ptr();
-            let len = self.len();
-            write_bytes(ptr, value as u8, len);
+    fn spec_fill(&mut self, value: T) {
+        if size_of::<T>() == 1 {
+            // SAFETY: The size_of check above ensures that values are 1 byte wide, as required
+            // for the transmute and write_bytes
+            unsafe {
+                let value: u8 = transmute_copy(&value);
+                write_bytes(self.as_mut_ptr(), value, self.len());
+            }
+        } else {
+            for item in self.iter_mut() {
+                *item = value;
+            }
         }
     }
 }

diff --git a/library/core/src/str/iter.rs b/library/core/src/str/iter.rs
index 4eac017..724137a 100644
--- a/library/core/src/str/iter.rs
+++ b/library/core/src/str/iter.rs

@@ -189,6 +189,30 @@
     pub fn as_str(&self) -> &'a str {
         self.iter.as_str()
     }
+
+    /// Returns the byte position of the next character, or the length
+    /// of the underlying string if there are no more characters.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(char_indices_offset)]
+    /// let mut chars = "a楽".char_indices();
+    ///
+    /// assert_eq!(chars.offset(), 0);
+    /// assert_eq!(chars.next(), Some((0, 'a')));
+    ///
+    /// assert_eq!(chars.offset(), 1);
+    /// assert_eq!(chars.next(), Some((1, '楽')));
+    ///
+    /// assert_eq!(chars.offset(), 4);
+    /// assert_eq!(chars.next(), None);
+    /// ```
+    #[inline]
+    #[unstable(feature = "char_indices_offset", issue = "83871")]
+    pub fn offset(&self) -> usize {
+        self.front_offset
+    }
 }
 
 /// An iterator over the bytes of a string slice.
@@ -1359,7 +1383,7 @@
 #[stable(feature = "collection_debug", since = "1.17.0")]
 impl fmt::Debug for EncodeUtf16<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.pad("EncodeUtf16 { .. }")
+        f.debug_struct("EncodeUtf16").finish_non_exhaustive()
     }
 }
 

diff --git a/library/core/src/str/mod.rs b/library/core/src/str/mod.rs
index 67c074b..95dd549 100644
--- a/library/core/src/str/mod.rs
+++ b/library/core/src/str/mod.rs

@@ -15,7 +15,7 @@
 use self::pattern::Pattern;
 use self::pattern::{DoubleEndedSearcher, ReverseSearcher, Searcher};
 
-use crate::char;
+use crate::char::{self, EscapeDebugExtArgs};
 use crate::mem;
 use crate::slice::{self, SliceIndex};
 
@@ -140,7 +140,7 @@
     /// ```
     #[doc(alias = "length")]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_str_len", since = "1.32.0")]
+    #[rustc_const_stable(feature = "const_str_len", since = "1.39.0")]
     #[inline]
     pub const fn len(&self) -> usize {
         self.as_bytes().len()
@@ -161,7 +161,7 @@
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_str_is_empty", since = "1.32.0")]
+    #[rustc_const_stable(feature = "const_str_is_empty", since = "1.39.0")]
     pub const fn is_empty(&self) -> bool {
         self.len() == 0
     }
@@ -217,7 +217,7 @@
     /// assert_eq!(b"bors", bytes);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "str_as_bytes", since = "1.32.0")]
+    #[rustc_const_stable(feature = "str_as_bytes", since = "1.39.0")]
     #[inline(always)]
     #[allow(unused_attributes)]
     #[rustc_allow_const_fn_unstable(const_fn_transmute)]
@@ -2342,7 +2342,7 @@
         EscapeDebug {
             inner: chars
                 .next()
-                .map(|first| first.escape_debug_ext(true))
+                .map(|first| first.escape_debug_ext(EscapeDebugExtArgs::ESCAPE_ALL))
                 .into_iter()
                 .flatten()
                 .chain(chars.flat_map(CharEscapeDebugContinue)),
@@ -2460,7 +2460,11 @@
 
     #[derive(Clone)]
     struct CharEscapeDebugContinue impl Fn = |c: char| -> char::EscapeDebug {
-        c.escape_debug_ext(false)
+        c.escape_debug_ext(EscapeDebugExtArgs {
+            escape_grapheme_extended: false,
+            escape_single_quote: true,
+            escape_double_quote: true
+        })
     };
 
     #[derive(Clone)]

diff --git a/library/core/src/sync/atomic.rs b/library/core/src/sync/atomic.rs
index ca39224..f1a1155 100644
--- a/library/core/src/sync/atomic.rs
+++ b/library/core/src/sync/atomic.rs

@@ -78,7 +78,7 @@
 //! ```
 //! use std::sync::Arc;
 //! use std::sync::atomic::{AtomicUsize, Ordering};
-//! use std::thread;
+//! use std::{hint, thread};
 //!
 //! fn main() {
 //!     let spinlock = Arc::new(AtomicUsize::new(1));
@@ -89,7 +89,9 @@
 //!     });
 //!
 //!     // Wait for the other thread to release the lock
-//!     while spinlock.load(Ordering::SeqCst) != 0 {}
+//!     while spinlock.load(Ordering::SeqCst) != 0 {
+//!         hint::spin_loop();
+//!     }
 //!
 //!     if let Err(panic) = thread.join() {
 //!         println!("Thread had an error: {:?}", panic);
@@ -283,7 +285,7 @@
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_atomic_new", since = "1.32.0")]
+    #[rustc_const_stable(feature = "const_atomic_new", since = "1.24.0")]
     pub const fn new(v: bool) -> AtomicBool {
         AtomicBool { v: UnsafeCell::new(v as u8) }
     }
@@ -837,7 +839,6 @@
     /// # Examples
     ///
     /// ```rust
-    /// #![feature(atomic_fetch_update)]
     /// use std::sync::atomic::{AtomicBool, Ordering};
     ///
     /// let x = AtomicBool::new(false);
@@ -847,7 +848,7 @@
     /// assert_eq!(x.load(Ordering::SeqCst), false);
     /// ```
     #[inline]
-    #[unstable(feature = "atomic_fetch_update", reason = "recently added", issue = "78639")]
+    #[stable(feature = "atomic_fetch_update", since = "1.53.0")]
     #[cfg(target_has_atomic = "8")]
     pub fn fetch_update<F>(
         &self,
@@ -883,7 +884,7 @@
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_atomic_new", since = "1.32.0")]
+    #[rustc_const_stable(feature = "const_atomic_new", since = "1.24.0")]
     pub const fn new(p: *mut T) -> AtomicPtr<T> {
         AtomicPtr { p: UnsafeCell::new(p) }
     }
@@ -898,8 +899,10 @@
     /// ```
     /// use std::sync::atomic::{AtomicPtr, Ordering};
     ///
-    /// let mut atomic_ptr = AtomicPtr::new(&mut 10);
-    /// *atomic_ptr.get_mut() = &mut 5;
+    /// let mut data = 10;
+    /// let mut atomic_ptr = AtomicPtr::new(&mut data);
+    /// let mut other_data = 5;
+    /// *atomic_ptr.get_mut() = &mut other_data;
     /// assert_eq!(unsafe { *atomic_ptr.load(Ordering::SeqCst) }, 5);
     /// ```
     #[inline]
@@ -916,9 +919,11 @@
     /// #![feature(atomic_from_mut)]
     /// use std::sync::atomic::{AtomicPtr, Ordering};
     ///
-    /// let mut some_ptr = &mut 123 as *mut i32;
+    /// let mut data = 123;
+    /// let mut some_ptr = &mut data as *mut i32;
     /// let a = AtomicPtr::from_mut(&mut some_ptr);
-    /// a.store(&mut 456, Ordering::Relaxed);
+    /// let mut other_data = 456;
+    /// a.store(&mut other_data, Ordering::Relaxed);
     /// assert_eq!(unsafe { *some_ptr }, 456);
     /// ```
     #[inline]
@@ -944,7 +949,8 @@
     /// ```
     /// use std::sync::atomic::AtomicPtr;
     ///
-    /// let atomic_ptr = AtomicPtr::new(&mut 5);
+    /// let mut data = 5;
+    /// let atomic_ptr = AtomicPtr::new(&mut data);
     /// assert_eq!(unsafe { *atomic_ptr.into_inner() }, 5);
     /// ```
     #[inline]
@@ -1220,7 +1226,6 @@
     /// # Examples
     ///
     /// ```rust
-    /// #![feature(atomic_fetch_update)]
     /// use std::sync::atomic::{AtomicPtr, Ordering};
     ///
     /// let ptr: *mut _ = &mut 5;
@@ -1239,7 +1244,7 @@
     /// assert_eq!(some_ptr.load(Ordering::SeqCst), new);
     /// ```
     #[inline]
-    #[unstable(feature = "atomic_fetch_update", reason = "recently added", issue = "78639")]
+    #[stable(feature = "atomic_fetch_update", since = "1.53.0")]
     #[cfg(target_has_atomic = "ptr")]
     pub fn fetch_update<F>(
         &self,
@@ -2276,7 +2281,7 @@
             stable(feature = "atomic_access", since = "1.15.0"),
             stable(feature = "atomic_from", since = "1.23.0"),
             stable(feature = "atomic_nand", since = "1.27.0"),
-            rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"),
+            rustc_const_stable(feature = "const_integer_atomics", since = "1.24.0"),
             stable(feature = "rust1", since = "1.0.0"),
             "isize",
             "",
@@ -2296,7 +2301,7 @@
             stable(feature = "atomic_access", since = "1.15.0"),
             stable(feature = "atomic_from", since = "1.23.0"),
             stable(feature = "atomic_nand", since = "1.27.0"),
-            rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"),
+            rustc_const_stable(feature = "const_integer_atomics", since = "1.24.0"),
             stable(feature = "rust1", since = "1.0.0"),
             "usize",
             "",

diff --git a/library/core/src/task/poll.rs b/library/core/src/task/poll.rs
index 42c9d9f..2765c21 100644
--- a/library/core/src/task/poll.rs
+++ b/library/core/src/task/poll.rs

@@ -1,6 +1,7 @@
 #![stable(feature = "futures_api", since = "1.36.0")]
 
-use crate::ops::Try;
+use crate::convert;
+use crate::ops::{self, ControlFlow, Try};
 use crate::result::Result;
 
 /// Indicates whether a value is available or if the current task has been
@@ -152,6 +153,36 @@
     }
 }
 
+#[unstable(feature = "try_trait_v2", issue = "84277")]
+impl<T, E> ops::TryV2 for Poll<Result<T, E>> {
+    type Output = Poll<T>;
+    type Residual = Result<convert::Infallible, E>;
+
+    #[inline]
+    fn from_output(c: Self::Output) -> Self {
+        c.map(Ok)
+    }
+
+    #[inline]
+    fn branch(self) -> ControlFlow<Self::Residual, Self::Output> {
+        match self {
+            Poll::Ready(Ok(x)) => ControlFlow::Continue(Poll::Ready(x)),
+            Poll::Ready(Err(e)) => ControlFlow::Break(Err(e)),
+            Poll::Pending => ControlFlow::Continue(Poll::Pending),
+        }
+    }
+}
+
+#[unstable(feature = "try_trait_v2", issue = "84277")]
+impl<T, E, F: From<E>> ops::FromResidual<Result<convert::Infallible, E>> for Poll<Result<T, F>> {
+    #[inline]
+    fn from_residual(x: Result<convert::Infallible, E>) -> Self {
+        match x {
+            Err(e) => Poll::Ready(Err(From::from(e))),
+        }
+    }
+}
+
 #[stable(feature = "futures_api", since = "1.36.0")]
 impl<T, E> Try for Poll<Option<Result<T, E>>> {
     type Ok = Poll<Option<T>>;
@@ -177,3 +208,36 @@
         x.map(|x| x.map(Ok))
     }
 }
+
+#[unstable(feature = "try_trait_v2", issue = "84277")]
+impl<T, E> ops::TryV2 for Poll<Option<Result<T, E>>> {
+    type Output = Poll<Option<T>>;
+    type Residual = Result<convert::Infallible, E>;
+
+    #[inline]
+    fn from_output(c: Self::Output) -> Self {
+        c.map(|x| x.map(Ok))
+    }
+
+    #[inline]
+    fn branch(self) -> ControlFlow<Self::Residual, Self::Output> {
+        match self {
+            Poll::Ready(Some(Ok(x))) => ControlFlow::Continue(Poll::Ready(Some(x))),
+            Poll::Ready(Some(Err(e))) => ControlFlow::Break(Err(e)),
+            Poll::Ready(None) => ControlFlow::Continue(Poll::Ready(None)),
+            Poll::Pending => ControlFlow::Continue(Poll::Pending),
+        }
+    }
+}
+
+#[unstable(feature = "try_trait_v2", issue = "84277")]
+impl<T, E, F: From<E>> ops::FromResidual<Result<convert::Infallible, E>>
+    for Poll<Option<Result<T, F>>>
+{
+    #[inline]
+    fn from_residual(x: Result<convert::Infallible, E>) -> Self {
+        match x {
+            Err(e) => Poll::Ready(Some(Err(From::from(e)))),
+        }
+    }
+}

diff --git a/library/core/src/time.rs b/library/core/src/time.rs
index 8c0848c..bfea39e 100644
--- a/library/core/src/time.rs
+++ b/library/core/src/time.rs

@@ -124,29 +124,32 @@
     /// # Examples
     ///
     /// ```
-    /// #![feature(duration_zero)]
     /// use std::time::Duration;
     ///
     /// let duration = Duration::ZERO;
     /// assert!(duration.is_zero());
     /// assert_eq!(duration.as_nanos(), 0);
     /// ```
-    #[unstable(feature = "duration_zero", issue = "73544")]
+    #[stable(feature = "duration_zero", since = "1.53.0")]
     pub const ZERO: Duration = Duration::from_nanos(0);
 
     /// The maximum duration.
     ///
-    /// It is roughly equal to a duration of 584,942,417,355 years.
+    /// May vary by platform as necessary. Must be able to contain the difference between
+    /// two instances of [`Instant`] or two instances of [`SystemTime`].
+    /// This constraint gives it a value of about 584,942,417,355 years in practice,
+    /// which is currently used on all platforms.
     ///
     /// # Examples
     ///
     /// ```
-    /// #![feature(duration_constants)]
     /// use std::time::Duration;
     ///
     /// assert_eq!(Duration::MAX, Duration::new(u64::MAX, 1_000_000_000 - 1));
     /// ```
-    #[unstable(feature = "duration_constants", issue = "57391")]
+    /// [`Instant`]: ../../std/time/struct.Instant.html
+    /// [`SystemTime`]: ../../std/time/struct.SystemTime.html
+    #[stable(feature = "duration_saturating_ops", since = "1.53.0")]
     pub const MAX: Duration = Duration::new(u64::MAX, NANOS_PER_SEC - 1);
 
     /// Creates a new `Duration` from the specified number of whole seconds and
@@ -269,7 +272,6 @@
     /// # Examples
     ///
     /// ```
-    /// #![feature(duration_zero)]
     /// use std::time::Duration;
     ///
     /// assert!(Duration::ZERO.is_zero());
@@ -281,7 +283,8 @@
     /// assert!(!Duration::from_nanos(1).is_zero());
     /// assert!(!Duration::from_secs(1).is_zero());
     /// ```
-    #[unstable(feature = "duration_zero", issue = "73544")]
+    #[stable(feature = "duration_zero", since = "1.53.0")]
+    #[rustc_const_stable(feature = "duration_zero", since = "1.53.0")]
     #[inline]
     pub const fn is_zero(&self) -> bool {
         self.secs == 0 && self.nanos == 0
@@ -479,14 +482,13 @@
     /// # Examples
     ///
     /// ```
-    /// #![feature(duration_saturating_ops)]
     /// #![feature(duration_constants)]
     /// use std::time::Duration;
     ///
     /// assert_eq!(Duration::new(0, 0).saturating_add(Duration::new(0, 1)), Duration::new(0, 1));
     /// assert_eq!(Duration::new(1, 0).saturating_add(Duration::new(u64::MAX, 0)), Duration::MAX);
     /// ```
-    #[unstable(feature = "duration_saturating_ops", issue = "76416")]
+    #[stable(feature = "duration_saturating_ops", since = "1.53.0")]
     #[inline]
     #[rustc_const_unstable(feature = "duration_consts_2", issue = "72440")]
     pub const fn saturating_add(self, rhs: Duration) -> Duration {
@@ -537,14 +539,12 @@
     /// # Examples
     ///
     /// ```
-    /// #![feature(duration_saturating_ops)]
-    /// #![feature(duration_zero)]
     /// use std::time::Duration;
     ///
     /// assert_eq!(Duration::new(0, 1).saturating_sub(Duration::new(0, 0)), Duration::new(0, 1));
     /// assert_eq!(Duration::new(0, 0).saturating_sub(Duration::new(0, 1)), Duration::ZERO);
     /// ```
-    #[unstable(feature = "duration_saturating_ops", issue = "76416")]
+    #[stable(feature = "duration_saturating_ops", since = "1.53.0")]
     #[inline]
     #[rustc_const_unstable(feature = "duration_consts_2", issue = "72440")]
     pub const fn saturating_sub(self, rhs: Duration) -> Duration {
@@ -590,14 +590,13 @@
     /// # Examples
     ///
     /// ```
-    /// #![feature(duration_saturating_ops)]
     /// #![feature(duration_constants)]
     /// use std::time::Duration;
     ///
     /// assert_eq!(Duration::new(0, 500_000_001).saturating_mul(2), Duration::new(1, 2));
     /// assert_eq!(Duration::new(u64::MAX - 1, 0).saturating_mul(2), Duration::MAX);
     /// ```
-    #[unstable(feature = "duration_saturating_ops", issue = "76416")]
+    #[stable(feature = "duration_saturating_ops", since = "1.53.0")]
     #[inline]
     #[rustc_const_unstable(feature = "duration_consts_2", issue = "72440")]
     pub const fn saturating_mul(self, rhs: u32) -> Duration {

diff --git a/library/core/tests/array.rs b/library/core/tests/array.rs
index 89c2a96..ce7480c 100644
--- a/library/core/tests/array.rs
+++ b/library/core/tests/array.rs

@@ -1,25 +1,7 @@
-use core::array::{self, FixedSizeArray, IntoIter};
+use core::array::{self, IntoIter};
 use core::convert::TryFrom;
 
 #[test]
-fn fixed_size_array() {
-    let mut array = [0; 64];
-    let mut zero_sized = [(); 64];
-    let mut empty_array = [0; 0];
-    let mut empty_zero_sized = [(); 0];
-
-    assert_eq!(FixedSizeArray::as_slice(&array).len(), 64);
-    assert_eq!(FixedSizeArray::as_slice(&zero_sized).len(), 64);
-    assert_eq!(FixedSizeArray::as_slice(&empty_array).len(), 0);
-    assert_eq!(FixedSizeArray::as_slice(&empty_zero_sized).len(), 0);
-
-    assert_eq!(FixedSizeArray::as_mut_slice(&mut array).len(), 64);
-    assert_eq!(FixedSizeArray::as_mut_slice(&mut zero_sized).len(), 64);
-    assert_eq!(FixedSizeArray::as_mut_slice(&mut empty_array).len(), 0);
-    assert_eq!(FixedSizeArray::as_mut_slice(&mut empty_zero_sized).len(), 0);
-}
-
-#[test]
 fn array_from_ref() {
     let value: String = "Hello World!".into();
     let arr: &[String; 1] = array::from_ref(&value);

diff --git a/library/core/tests/const_ptr.rs b/library/core/tests/const_ptr.rs
index 4158a4d..4acd059 100644
--- a/library/core/tests/const_ptr.rs
+++ b/library/core/tests/const_ptr.rs

@@ -49,53 +49,3 @@
     const UNALIGNED: u16 = unsafe { UNALIGNED_PTR.read_unaligned() };
     assert_eq!(UNALIGNED, u16::from_ne_bytes([0x23, 0x45]));
 }
-
-//#[test]
-//fn write() {
-//    use core::ptr;
-//
-//    const fn write_aligned() -> i32 {
-//        let mut res = 0;
-//        unsafe {
-//            ptr::write(&mut res as *mut _, 42);
-//        }
-//        res
-//    }
-//    const ALIGNED: i32 = write_aligned();
-//    assert_eq!(ALIGNED, 42);
-//
-//    const fn write_unaligned() -> [u16; 2] {
-//        let mut two_aligned = [0u16; 2];
-//        unsafe {
-//            let unaligned_ptr = (two_aligned.as_mut_ptr() as *mut u8).add(1) as *mut u16;
-//            ptr::write_unaligned(unaligned_ptr, u16::from_ne_bytes([0x23, 0x45]));
-//        }
-//        two_aligned
-//    }
-//    const UNALIGNED: [u16; 2] = write_unaligned();
-//    assert_eq!(UNALIGNED, [u16::from_ne_bytes([0x00, 0x23]), u16::from_ne_bytes([0x45, 0x00])]);
-//}
-
-//#[test]
-//fn mut_ptr_write() {
-//    const fn aligned() -> i32 {
-//        let mut res = 0;
-//        unsafe {
-//            (&mut res as *mut i32).write(42);
-//        }
-//        res
-//    }
-//    const ALIGNED: i32 = aligned();
-//    assert_eq!(ALIGNED, 42);
-//
-//    const fn write_unaligned() -> [u16; 2] {
-//        let mut two_aligned = [0u16; 2];
-//        unsafe {
-//            let unaligned_ptr = (two_aligned.as_mut_ptr() as *mut u8).add(1) as *mut u16;
-//            unaligned_ptr.write_unaligned(u16::from_ne_bytes([0x23, 0x45]));
-//        }
-//        two_aligned
-//    }
-//    const UNALIGNED: [u16; 2] = write_unaligned();
-//    assert_eq!(UNALIGNED, [u16::from_ne_bytes([0x00, 0x23]), u16::from_ne_bytes([0x45, 0x00])]);
-//}

diff --git a/library/core/tests/fmt/builders.rs b/library/core/tests/fmt/builders.rs
index 129c121..7580010 100644
--- a/library/core/tests/fmt/builders.rs
+++ b/library/core/tests/fmt/builders.rs

@@ -105,12 +105,7 @@
         }
 
         assert_eq!("Foo { .. }", format!("{:?}", Foo));
-        assert_eq!(
-            "Foo {
-    ..
-}",
-            format!("{:#?}", Foo)
-        );
+        assert_eq!("Foo { .. }", format!("{:#?}", Foo));
     }
 
     #[test]

diff --git a/library/core/tests/iter/adapters/chain.rs b/library/core/tests/iter/adapters/chain.rs
index ca5ae12..4cd7968 100644
--- a/library/core/tests/iter/adapters/chain.rs
+++ b/library/core/tests/iter/adapters/chain.rs

@@ -174,14 +174,14 @@
 fn test_iterator_chain_unfused() {
     // Chain shouldn't be fused in its second iterator, depending on direction
     let mut iter = NonFused::new(empty()).chain(Toggle { is_empty: true });
-    iter.next().unwrap_none();
-    iter.next().unwrap();
-    iter.next().unwrap_none();
+    assert!(iter.next().is_none());
+    assert!(iter.next().is_some());
+    assert!(iter.next().is_none());
 
     let mut iter = Toggle { is_empty: true }.chain(NonFused::new(empty()));
-    iter.next_back().unwrap_none();
-    iter.next_back().unwrap();
-    iter.next_back().unwrap_none();
+    assert!(iter.next_back().is_none());
+    assert!(iter.next_back().is_some());
+    assert!(iter.next_back().is_none());
 }
 
 #[test]

diff --git a/library/core/tests/lib.rs b/library/core/tests/lib.rs
index b7fcc74..35e4d21 100644
--- a/library/core/tests/lib.rs
+++ b/library/core/tests/lib.rs

@@ -1,6 +1,5 @@
 #![feature(alloc_layout_extra)]
 #![feature(array_chunks)]
-#![feature(array_from_ref)]
 #![feature(array_methods)]
 #![feature(array_map)]
 #![feature(array_windows)]
@@ -20,16 +19,12 @@
 #![feature(core_intrinsics)]
 #![feature(core_private_bignum)]
 #![feature(core_private_diy_float)]
-#![feature(debug_non_exhaustive)]
 #![feature(dec2flt)]
 #![feature(div_duration)]
 #![feature(duration_consts_2)]
 #![feature(duration_constants)]
-#![feature(duration_saturating_ops)]
-#![feature(duration_zero)]
 #![feature(exact_size_is_empty)]
 #![feature(extern_types)]
-#![feature(fixed_size_array)]
 #![feature(flt2dec)]
 #![feature(fmt_internals)]
 #![feature(hashmap_internals)]
@@ -58,7 +53,6 @@
 #![feature(iter_intersperse)]
 #![feature(iter_is_partitioned)]
 #![feature(iter_order_by)]
-#![feature(cmp_min_max_by)]
 #![feature(iter_map_while)]
 #![feature(const_mut_refs)]
 #![feature(const_pin)]
@@ -68,19 +62,14 @@
 #![feature(unwrap_infallible)]
 #![feature(option_result_unwrap_unchecked)]
 #![feature(result_into_ok_or_err)]
-#![feature(option_unwrap_none)]
-#![feature(peekable_peek_mut)]
-#![cfg_attr(not(bootstrap), feature(ptr_metadata))]
+#![feature(ptr_metadata)]
 #![feature(once_cell)]
 #![feature(unsized_tuple_coercion)]
-#![feature(int_bits_const)]
-#![feature(nonzero_leading_trailing_zeros)]
 #![feature(const_option)]
 #![feature(integer_atomics)]
 #![feature(slice_group_by)]
 #![feature(trusted_random_access)]
-#![cfg_attr(bootstrap, feature(unsafe_block_in_unsafe_fn))]
-#![cfg_attr(not(bootstrap), feature(unsize))]
+#![feature(unsize)]
 #![deny(unsafe_op_in_unsafe_fn)]
 
 extern crate test;

diff --git a/library/core/tests/mem.rs b/library/core/tests/mem.rs
index c0b7503..dfdbc93 100644
--- a/library/core/tests/mem.rs
+++ b/library/core/tests/mem.rs

@@ -97,6 +97,9 @@
     assert_eq!(1, unsafe { transmute_copy(&1) });
 }
 
+// Remove this test when `std::raw` is removed.
+// The replacement pointer metadata APIs are tested in library/core/tests/ptr.rs
+#[allow(deprecated)]
 #[test]
 fn test_transmute() {
     trait Foo {

diff --git a/library/core/tests/num/flt2dec/mod.rs b/library/core/tests/num/flt2dec/mod.rs
index 8e95249..960a7ca 100644
--- a/library/core/tests/num/flt2dec/mod.rs
+++ b/library/core/tests/num/flt2dec/mod.rs

@@ -514,51 +514,38 @@
     let f = &mut f_;
 
     assert_eq!(to_string(f, 0.0, Minus, 0), "0");
-    assert_eq!(to_string(f, 0.0, MinusRaw, 0), "0");
+    assert_eq!(to_string(f, 0.0, Minus, 0), "0");
     assert_eq!(to_string(f, 0.0, MinusPlus, 0), "+0");
-    assert_eq!(to_string(f, 0.0, MinusPlusRaw, 0), "+0");
-    assert_eq!(to_string(f, -0.0, Minus, 0), "0");
-    assert_eq!(to_string(f, -0.0, MinusRaw, 0), "-0");
-    assert_eq!(to_string(f, -0.0, MinusPlus, 0), "+0");
-    assert_eq!(to_string(f, -0.0, MinusPlusRaw, 0), "-0");
+    assert_eq!(to_string(f, -0.0, Minus, 0), "-0");
+    assert_eq!(to_string(f, -0.0, MinusPlus, 0), "-0");
     assert_eq!(to_string(f, 0.0, Minus, 1), "0.0");
-    assert_eq!(to_string(f, 0.0, MinusRaw, 1), "0.0");
+    assert_eq!(to_string(f, 0.0, Minus, 1), "0.0");
     assert_eq!(to_string(f, 0.0, MinusPlus, 1), "+0.0");
-    assert_eq!(to_string(f, 0.0, MinusPlusRaw, 1), "+0.0");
-    assert_eq!(to_string(f, -0.0, Minus, 8), "0.00000000");
-    assert_eq!(to_string(f, -0.0, MinusRaw, 8), "-0.00000000");
-    assert_eq!(to_string(f, -0.0, MinusPlus, 8), "+0.00000000");
-    assert_eq!(to_string(f, -0.0, MinusPlusRaw, 8), "-0.00000000");
+    assert_eq!(to_string(f, -0.0, Minus, 8), "-0.00000000");
+    assert_eq!(to_string(f, -0.0, MinusPlus, 8), "-0.00000000");
 
     assert_eq!(to_string(f, 1.0 / 0.0, Minus, 0), "inf");
-    assert_eq!(to_string(f, 1.0 / 0.0, MinusRaw, 0), "inf");
+    assert_eq!(to_string(f, 1.0 / 0.0, Minus, 0), "inf");
     assert_eq!(to_string(f, 1.0 / 0.0, MinusPlus, 0), "+inf");
-    assert_eq!(to_string(f, 1.0 / 0.0, MinusPlusRaw, 0), "+inf");
     assert_eq!(to_string(f, 0.0 / 0.0, Minus, 0), "NaN");
-    assert_eq!(to_string(f, 0.0 / 0.0, MinusRaw, 1), "NaN");
-    assert_eq!(to_string(f, 0.0 / 0.0, MinusPlus, 8), "NaN");
-    assert_eq!(to_string(f, 0.0 / 0.0, MinusPlusRaw, 64), "NaN");
+    assert_eq!(to_string(f, 0.0 / 0.0, Minus, 1), "NaN");
+    assert_eq!(to_string(f, 0.0 / 0.0, MinusPlus, 64), "NaN");
     assert_eq!(to_string(f, -1.0 / 0.0, Minus, 0), "-inf");
-    assert_eq!(to_string(f, -1.0 / 0.0, MinusRaw, 1), "-inf");
-    assert_eq!(to_string(f, -1.0 / 0.0, MinusPlus, 8), "-inf");
-    assert_eq!(to_string(f, -1.0 / 0.0, MinusPlusRaw, 64), "-inf");
+    assert_eq!(to_string(f, -1.0 / 0.0, Minus, 1), "-inf");
+    assert_eq!(to_string(f, -1.0 / 0.0, MinusPlus, 64), "-inf");
 
     assert_eq!(to_string(f, 3.14, Minus, 0), "3.14");
-    assert_eq!(to_string(f, 3.14, MinusRaw, 0), "3.14");
+    assert_eq!(to_string(f, 3.14, Minus, 0), "3.14");
     assert_eq!(to_string(f, 3.14, MinusPlus, 0), "+3.14");
-    assert_eq!(to_string(f, 3.14, MinusPlusRaw, 0), "+3.14");
     assert_eq!(to_string(f, -3.14, Minus, 0), "-3.14");
-    assert_eq!(to_string(f, -3.14, MinusRaw, 0), "-3.14");
+    assert_eq!(to_string(f, -3.14, Minus, 0), "-3.14");
     assert_eq!(to_string(f, -3.14, MinusPlus, 0), "-3.14");
-    assert_eq!(to_string(f, -3.14, MinusPlusRaw, 0), "-3.14");
     assert_eq!(to_string(f, 3.14, Minus, 1), "3.14");
-    assert_eq!(to_string(f, 3.14, MinusRaw, 2), "3.14");
-    assert_eq!(to_string(f, 3.14, MinusPlus, 3), "+3.140");
-    assert_eq!(to_string(f, 3.14, MinusPlusRaw, 4), "+3.1400");
+    assert_eq!(to_string(f, 3.14, Minus, 2), "3.14");
+    assert_eq!(to_string(f, 3.14, MinusPlus, 4), "+3.1400");
     assert_eq!(to_string(f, -3.14, Minus, 8), "-3.14000000");
-    assert_eq!(to_string(f, -3.14, MinusRaw, 8), "-3.14000000");
+    assert_eq!(to_string(f, -3.14, Minus, 8), "-3.14000000");
     assert_eq!(to_string(f, -3.14, MinusPlus, 8), "-3.14000000");
-    assert_eq!(to_string(f, -3.14, MinusPlusRaw, 8), "-3.14000000");
 
     assert_eq!(to_string(f, 7.5e-11, Minus, 0), "0.000000000075");
     assert_eq!(to_string(f, 7.5e-11, Minus, 3), "0.000000000075");
@@ -615,68 +602,48 @@
     let f = &mut f_;
 
     assert_eq!(to_string(f, 0.0, Minus, (-4, 16), false), "0");
-    assert_eq!(to_string(f, 0.0, MinusRaw, (-4, 16), false), "0");
+    assert_eq!(to_string(f, 0.0, Minus, (-4, 16), false), "0");
     assert_eq!(to_string(f, 0.0, MinusPlus, (-4, 16), false), "+0");
-    assert_eq!(to_string(f, 0.0, MinusPlusRaw, (-4, 16), false), "+0");
-    assert_eq!(to_string(f, -0.0, Minus, (-4, 16), false), "0");
-    assert_eq!(to_string(f, -0.0, MinusRaw, (-4, 16), false), "-0");
-    assert_eq!(to_string(f, -0.0, MinusPlus, (-4, 16), false), "+0");
-    assert_eq!(to_string(f, -0.0, MinusPlusRaw, (-4, 16), false), "-0");
+    assert_eq!(to_string(f, -0.0, Minus, (-4, 16), false), "-0");
+    assert_eq!(to_string(f, -0.0, MinusPlus, (-4, 16), false), "-0");
     assert_eq!(to_string(f, 0.0, Minus, (0, 0), true), "0E0");
-    assert_eq!(to_string(f, 0.0, MinusRaw, (0, 0), false), "0e0");
-    assert_eq!(to_string(f, 0.0, MinusPlus, (-9, -5), true), "+0E0");
-    assert_eq!(to_string(f, 0.0, MinusPlusRaw, (5, 9), false), "+0e0");
-    assert_eq!(to_string(f, -0.0, Minus, (0, 0), true), "0E0");
-    assert_eq!(to_string(f, -0.0, MinusRaw, (0, 0), false), "-0e0");
-    assert_eq!(to_string(f, -0.0, MinusPlus, (-9, -5), true), "+0E0");
-    assert_eq!(to_string(f, -0.0, MinusPlusRaw, (5, 9), false), "-0e0");
+    assert_eq!(to_string(f, 0.0, Minus, (0, 0), false), "0e0");
+    assert_eq!(to_string(f, 0.0, MinusPlus, (5, 9), false), "+0e0");
+    assert_eq!(to_string(f, -0.0, Minus, (0, 0), true), "-0E0");
+    assert_eq!(to_string(f, -0.0, MinusPlus, (5, 9), false), "-0e0");
 
     assert_eq!(to_string(f, 1.0 / 0.0, Minus, (-4, 16), false), "inf");
-    assert_eq!(to_string(f, 1.0 / 0.0, MinusRaw, (-4, 16), true), "inf");
-    assert_eq!(to_string(f, 1.0 / 0.0, MinusPlus, (-4, 16), false), "+inf");
-    assert_eq!(to_string(f, 1.0 / 0.0, MinusPlusRaw, (-4, 16), true), "+inf");
+    assert_eq!(to_string(f, 1.0 / 0.0, Minus, (-4, 16), true), "inf");
+    assert_eq!(to_string(f, 1.0 / 0.0, MinusPlus, (-4, 16), true), "+inf");
     assert_eq!(to_string(f, 0.0 / 0.0, Minus, (0, 0), false), "NaN");
-    assert_eq!(to_string(f, 0.0 / 0.0, MinusRaw, (0, 0), true), "NaN");
-    assert_eq!(to_string(f, 0.0 / 0.0, MinusPlus, (-9, -5), false), "NaN");
-    assert_eq!(to_string(f, 0.0 / 0.0, MinusPlusRaw, (5, 9), true), "NaN");
+    assert_eq!(to_string(f, 0.0 / 0.0, Minus, (0, 0), true), "NaN");
+    assert_eq!(to_string(f, 0.0 / 0.0, MinusPlus, (5, 9), true), "NaN");
     assert_eq!(to_string(f, -1.0 / 0.0, Minus, (0, 0), false), "-inf");
-    assert_eq!(to_string(f, -1.0 / 0.0, MinusRaw, (0, 0), true), "-inf");
-    assert_eq!(to_string(f, -1.0 / 0.0, MinusPlus, (-9, -5), false), "-inf");
-    assert_eq!(to_string(f, -1.0 / 0.0, MinusPlusRaw, (5, 9), true), "-inf");
+    assert_eq!(to_string(f, -1.0 / 0.0, Minus, (0, 0), true), "-inf");
+    assert_eq!(to_string(f, -1.0 / 0.0, MinusPlus, (5, 9), true), "-inf");
 
     assert_eq!(to_string(f, 3.14, Minus, (-4, 16), false), "3.14");
-    assert_eq!(to_string(f, 3.14, MinusRaw, (-4, 16), false), "3.14");
     assert_eq!(to_string(f, 3.14, MinusPlus, (-4, 16), false), "+3.14");
-    assert_eq!(to_string(f, 3.14, MinusPlusRaw, (-4, 16), false), "+3.14");
     assert_eq!(to_string(f, -3.14, Minus, (-4, 16), false), "-3.14");
-    assert_eq!(to_string(f, -3.14, MinusRaw, (-4, 16), false), "-3.14");
     assert_eq!(to_string(f, -3.14, MinusPlus, (-4, 16), false), "-3.14");
-    assert_eq!(to_string(f, -3.14, MinusPlusRaw, (-4, 16), false), "-3.14");
     assert_eq!(to_string(f, 3.14, Minus, (0, 0), true), "3.14E0");
-    assert_eq!(to_string(f, 3.14, MinusRaw, (0, 0), false), "3.14e0");
-    assert_eq!(to_string(f, 3.14, MinusPlus, (-9, -5), true), "+3.14E0");
-    assert_eq!(to_string(f, 3.14, MinusPlusRaw, (5, 9), false), "+3.14e0");
+    assert_eq!(to_string(f, 3.14, Minus, (0, 0), false), "3.14e0");
+    assert_eq!(to_string(f, 3.14, MinusPlus, (5, 9), false), "+3.14e0");
     assert_eq!(to_string(f, -3.14, Minus, (0, 0), true), "-3.14E0");
-    assert_eq!(to_string(f, -3.14, MinusRaw, (0, 0), false), "-3.14e0");
-    assert_eq!(to_string(f, -3.14, MinusPlus, (-9, -5), true), "-3.14E0");
-    assert_eq!(to_string(f, -3.14, MinusPlusRaw, (5, 9), false), "-3.14e0");
+    assert_eq!(to_string(f, -3.14, Minus, (0, 0), false), "-3.14e0");
+    assert_eq!(to_string(f, -3.14, MinusPlus, (5, 9), false), "-3.14e0");
 
     assert_eq!(to_string(f, 0.1, Minus, (-4, 16), false), "0.1");
-    assert_eq!(to_string(f, 0.1, MinusRaw, (-4, 16), false), "0.1");
+    assert_eq!(to_string(f, 0.1, Minus, (-4, 16), false), "0.1");
     assert_eq!(to_string(f, 0.1, MinusPlus, (-4, 16), false), "+0.1");
-    assert_eq!(to_string(f, 0.1, MinusPlusRaw, (-4, 16), false), "+0.1");
     assert_eq!(to_string(f, -0.1, Minus, (-4, 16), false), "-0.1");
-    assert_eq!(to_string(f, -0.1, MinusRaw, (-4, 16), false), "-0.1");
     assert_eq!(to_string(f, -0.1, MinusPlus, (-4, 16), false), "-0.1");
-    assert_eq!(to_string(f, -0.1, MinusPlusRaw, (-4, 16), false), "-0.1");
     assert_eq!(to_string(f, 0.1, Minus, (0, 0), true), "1E-1");
-    assert_eq!(to_string(f, 0.1, MinusRaw, (0, 0), false), "1e-1");
-    assert_eq!(to_string(f, 0.1, MinusPlus, (-9, -5), true), "+1E-1");
-    assert_eq!(to_string(f, 0.1, MinusPlusRaw, (5, 9), false), "+1e-1");
+    assert_eq!(to_string(f, 0.1, Minus, (0, 0), false), "1e-1");
+    assert_eq!(to_string(f, 0.1, MinusPlus, (5, 9), false), "+1e-1");
     assert_eq!(to_string(f, -0.1, Minus, (0, 0), true), "-1E-1");
-    assert_eq!(to_string(f, -0.1, MinusRaw, (0, 0), false), "-1e-1");
-    assert_eq!(to_string(f, -0.1, MinusPlus, (-9, -5), true), "-1E-1");
-    assert_eq!(to_string(f, -0.1, MinusPlusRaw, (5, 9), false), "-1e-1");
+    assert_eq!(to_string(f, -0.1, Minus, (0, 0), false), "-1e-1");
+    assert_eq!(to_string(f, -0.1, MinusPlus, (5, 9), false), "-1e-1");
 
     assert_eq!(to_string(f, 7.5e-11, Minus, (-4, 16), false), "7.5e-11");
     assert_eq!(to_string(f, 7.5e-11, Minus, (-11, 10), false), "0.000000000075");
@@ -734,68 +701,51 @@
     let f = &mut f_;
 
     assert_eq!(to_string(f, 0.0, Minus, 1, true), "0E0");
-    assert_eq!(to_string(f, 0.0, MinusRaw, 1, false), "0e0");
-    assert_eq!(to_string(f, 0.0, MinusPlus, 1, true), "+0E0");
-    assert_eq!(to_string(f, 0.0, MinusPlusRaw, 1, false), "+0e0");
-    assert_eq!(to_string(f, -0.0, Minus, 1, true), "0E0");
-    assert_eq!(to_string(f, -0.0, MinusRaw, 1, false), "-0e0");
-    assert_eq!(to_string(f, -0.0, MinusPlus, 1, true), "+0E0");
-    assert_eq!(to_string(f, -0.0, MinusPlusRaw, 1, false), "-0e0");
+    assert_eq!(to_string(f, 0.0, Minus, 1, false), "0e0");
+    assert_eq!(to_string(f, 0.0, MinusPlus, 1, false), "+0e0");
+    assert_eq!(to_string(f, -0.0, Minus, 1, true), "-0E0");
+    assert_eq!(to_string(f, -0.0, MinusPlus, 1, false), "-0e0");
     assert_eq!(to_string(f, 0.0, Minus, 2, true), "0.0E0");
-    assert_eq!(to_string(f, 0.0, MinusRaw, 2, false), "0.0e0");
-    assert_eq!(to_string(f, 0.0, MinusPlus, 2, true), "+0.0E0");
-    assert_eq!(to_string(f, 0.0, MinusPlusRaw, 2, false), "+0.0e0");
-    assert_eq!(to_string(f, -0.0, Minus, 8, true), "0.0000000E0");
-    assert_eq!(to_string(f, -0.0, MinusRaw, 8, false), "-0.0000000e0");
-    assert_eq!(to_string(f, -0.0, MinusPlus, 8, true), "+0.0000000E0");
-    assert_eq!(to_string(f, -0.0, MinusPlusRaw, 8, false), "-0.0000000e0");
+    assert_eq!(to_string(f, 0.0, Minus, 2, false), "0.0e0");
+    assert_eq!(to_string(f, 0.0, MinusPlus, 2, false), "+0.0e0");
+    assert_eq!(to_string(f, -0.0, Minus, 8, false), "-0.0000000e0");
+    assert_eq!(to_string(f, -0.0, MinusPlus, 8, false), "-0.0000000e0");
 
     assert_eq!(to_string(f, 1.0 / 0.0, Minus, 1, false), "inf");
-    assert_eq!(to_string(f, 1.0 / 0.0, MinusRaw, 1, true), "inf");
-    assert_eq!(to_string(f, 1.0 / 0.0, MinusPlus, 1, false), "+inf");
-    assert_eq!(to_string(f, 1.0 / 0.0, MinusPlusRaw, 1, true), "+inf");
+    assert_eq!(to_string(f, 1.0 / 0.0, Minus, 1, true), "inf");
+    assert_eq!(to_string(f, 1.0 / 0.0, MinusPlus, 1, true), "+inf");
     assert_eq!(to_string(f, 0.0 / 0.0, Minus, 8, false), "NaN");
-    assert_eq!(to_string(f, 0.0 / 0.0, MinusRaw, 8, true), "NaN");
-    assert_eq!(to_string(f, 0.0 / 0.0, MinusPlus, 8, false), "NaN");
-    assert_eq!(to_string(f, 0.0 / 0.0, MinusPlusRaw, 8, true), "NaN");
+    assert_eq!(to_string(f, 0.0 / 0.0, Minus, 8, true), "NaN");
+    assert_eq!(to_string(f, 0.0 / 0.0, MinusPlus, 8, true), "NaN");
     assert_eq!(to_string(f, -1.0 / 0.0, Minus, 64, false), "-inf");
-    assert_eq!(to_string(f, -1.0 / 0.0, MinusRaw, 64, true), "-inf");
-    assert_eq!(to_string(f, -1.0 / 0.0, MinusPlus, 64, false), "-inf");
-    assert_eq!(to_string(f, -1.0 / 0.0, MinusPlusRaw, 64, true), "-inf");
+    assert_eq!(to_string(f, -1.0 / 0.0, Minus, 64, true), "-inf");
+    assert_eq!(to_string(f, -1.0 / 0.0, MinusPlus, 64, true), "-inf");
 
     assert_eq!(to_string(f, 3.14, Minus, 1, true), "3E0");
-    assert_eq!(to_string(f, 3.14, MinusRaw, 1, false), "3e0");
-    assert_eq!(to_string(f, 3.14, MinusPlus, 1, true), "+3E0");
-    assert_eq!(to_string(f, 3.14, MinusPlusRaw, 1, false), "+3e0");
+    assert_eq!(to_string(f, 3.14, Minus, 1, false), "3e0");
+    assert_eq!(to_string(f, 3.14, MinusPlus, 1, false), "+3e0");
     assert_eq!(to_string(f, -3.14, Minus, 2, true), "-3.1E0");
-    assert_eq!(to_string(f, -3.14, MinusRaw, 2, false), "-3.1e0");
-    assert_eq!(to_string(f, -3.14, MinusPlus, 2, true), "-3.1E0");
-    assert_eq!(to_string(f, -3.14, MinusPlusRaw, 2, false), "-3.1e0");
+    assert_eq!(to_string(f, -3.14, Minus, 2, false), "-3.1e0");
+    assert_eq!(to_string(f, -3.14, MinusPlus, 2, false), "-3.1e0");
     assert_eq!(to_string(f, 3.14, Minus, 3, true), "3.14E0");
-    assert_eq!(to_string(f, 3.14, MinusRaw, 3, false), "3.14e0");
-    assert_eq!(to_string(f, 3.14, MinusPlus, 3, true), "+3.14E0");
-    assert_eq!(to_string(f, 3.14, MinusPlusRaw, 3, false), "+3.14e0");
+    assert_eq!(to_string(f, 3.14, Minus, 3, false), "3.14e0");
+    assert_eq!(to_string(f, 3.14, MinusPlus, 3, false), "+3.14e0");
     assert_eq!(to_string(f, -3.14, Minus, 4, true), "-3.140E0");
-    assert_eq!(to_string(f, -3.14, MinusRaw, 4, false), "-3.140e0");
-    assert_eq!(to_string(f, -3.14, MinusPlus, 4, true), "-3.140E0");
-    assert_eq!(to_string(f, -3.14, MinusPlusRaw, 4, false), "-3.140e0");
+    assert_eq!(to_string(f, -3.14, Minus, 4, false), "-3.140e0");
+    assert_eq!(to_string(f, -3.14, MinusPlus, 4, false), "-3.140e0");
 
     assert_eq!(to_string(f, 0.195, Minus, 1, false), "2e-1");
-    assert_eq!(to_string(f, 0.195, MinusRaw, 1, true), "2E-1");
-    assert_eq!(to_string(f, 0.195, MinusPlus, 1, false), "+2e-1");
-    assert_eq!(to_string(f, 0.195, MinusPlusRaw, 1, true), "+2E-1");
+    assert_eq!(to_string(f, 0.195, Minus, 1, true), "2E-1");
+    assert_eq!(to_string(f, 0.195, MinusPlus, 1, true), "+2E-1");
     assert_eq!(to_string(f, -0.195, Minus, 2, false), "-2.0e-1");
-    assert_eq!(to_string(f, -0.195, MinusRaw, 2, true), "-2.0E-1");
-    assert_eq!(to_string(f, -0.195, MinusPlus, 2, false), "-2.0e-1");
-    assert_eq!(to_string(f, -0.195, MinusPlusRaw, 2, true), "-2.0E-1");
+    assert_eq!(to_string(f, -0.195, Minus, 2, true), "-2.0E-1");
+    assert_eq!(to_string(f, -0.195, MinusPlus, 2, true), "-2.0E-1");
     assert_eq!(to_string(f, 0.195, Minus, 3, false), "1.95e-1");
-    assert_eq!(to_string(f, 0.195, MinusRaw, 3, true), "1.95E-1");
-    assert_eq!(to_string(f, 0.195, MinusPlus, 3, false), "+1.95e-1");
-    assert_eq!(to_string(f, 0.195, MinusPlusRaw, 3, true), "+1.95E-1");
+    assert_eq!(to_string(f, 0.195, Minus, 3, true), "1.95E-1");
+    assert_eq!(to_string(f, 0.195, MinusPlus, 3, true), "+1.95E-1");
     assert_eq!(to_string(f, -0.195, Minus, 4, false), "-1.950e-1");
-    assert_eq!(to_string(f, -0.195, MinusRaw, 4, true), "-1.950E-1");
-    assert_eq!(to_string(f, -0.195, MinusPlus, 4, false), "-1.950e-1");
-    assert_eq!(to_string(f, -0.195, MinusPlusRaw, 4, true), "-1.950E-1");
+    assert_eq!(to_string(f, -0.195, Minus, 4, true), "-1.950E-1");
+    assert_eq!(to_string(f, -0.195, MinusPlus, 4, true), "-1.950E-1");
 
     assert_eq!(to_string(f, 9.5, Minus, 1, false), "1e1");
     assert_eq!(to_string(f, 9.5, Minus, 2, false), "9.5e0");
@@ -1007,68 +957,48 @@
     let f = &mut f_;
 
     assert_eq!(to_string(f, 0.0, Minus, 0), "0");
-    assert_eq!(to_string(f, 0.0, MinusRaw, 0), "0");
     assert_eq!(to_string(f, 0.0, MinusPlus, 0), "+0");
-    assert_eq!(to_string(f, 0.0, MinusPlusRaw, 0), "+0");
-    assert_eq!(to_string(f, -0.0, Minus, 0), "0");
-    assert_eq!(to_string(f, -0.0, MinusRaw, 0), "-0");
-    assert_eq!(to_string(f, -0.0, MinusPlus, 0), "+0");
-    assert_eq!(to_string(f, -0.0, MinusPlusRaw, 0), "-0");
+    assert_eq!(to_string(f, -0.0, Minus, 0), "-0");
+    assert_eq!(to_string(f, -0.0, MinusPlus, 0), "-0");
     assert_eq!(to_string(f, 0.0, Minus, 1), "0.0");
-    assert_eq!(to_string(f, 0.0, MinusRaw, 1), "0.0");
     assert_eq!(to_string(f, 0.0, MinusPlus, 1), "+0.0");
-    assert_eq!(to_string(f, 0.0, MinusPlusRaw, 1), "+0.0");
-    assert_eq!(to_string(f, -0.0, Minus, 8), "0.00000000");
-    assert_eq!(to_string(f, -0.0, MinusRaw, 8), "-0.00000000");
-    assert_eq!(to_string(f, -0.0, MinusPlus, 8), "+0.00000000");
-    assert_eq!(to_string(f, -0.0, MinusPlusRaw, 8), "-0.00000000");
+    assert_eq!(to_string(f, -0.0, Minus, 8), "-0.00000000");
+    assert_eq!(to_string(f, -0.0, MinusPlus, 8), "-0.00000000");
 
     assert_eq!(to_string(f, 1.0 / 0.0, Minus, 0), "inf");
-    assert_eq!(to_string(f, 1.0 / 0.0, MinusRaw, 1), "inf");
-    assert_eq!(to_string(f, 1.0 / 0.0, MinusPlus, 8), "+inf");
-    assert_eq!(to_string(f, 1.0 / 0.0, MinusPlusRaw, 64), "+inf");
+    assert_eq!(to_string(f, 1.0 / 0.0, Minus, 1), "inf");
+    assert_eq!(to_string(f, 1.0 / 0.0, MinusPlus, 64), "+inf");
     assert_eq!(to_string(f, 0.0 / 0.0, Minus, 0), "NaN");
-    assert_eq!(to_string(f, 0.0 / 0.0, MinusRaw, 1), "NaN");
-    assert_eq!(to_string(f, 0.0 / 0.0, MinusPlus, 8), "NaN");
-    assert_eq!(to_string(f, 0.0 / 0.0, MinusPlusRaw, 64), "NaN");
+    assert_eq!(to_string(f, 0.0 / 0.0, Minus, 1), "NaN");
+    assert_eq!(to_string(f, 0.0 / 0.0, MinusPlus, 64), "NaN");
     assert_eq!(to_string(f, -1.0 / 0.0, Minus, 0), "-inf");
-    assert_eq!(to_string(f, -1.0 / 0.0, MinusRaw, 1), "-inf");
-    assert_eq!(to_string(f, -1.0 / 0.0, MinusPlus, 8), "-inf");
-    assert_eq!(to_string(f, -1.0 / 0.0, MinusPlusRaw, 64), "-inf");
+    assert_eq!(to_string(f, -1.0 / 0.0, Minus, 1), "-inf");
+    assert_eq!(to_string(f, -1.0 / 0.0, MinusPlus, 64), "-inf");
 
     assert_eq!(to_string(f, 3.14, Minus, 0), "3");
-    assert_eq!(to_string(f, 3.14, MinusRaw, 0), "3");
+    assert_eq!(to_string(f, 3.14, Minus, 0), "3");
     assert_eq!(to_string(f, 3.14, MinusPlus, 0), "+3");
-    assert_eq!(to_string(f, 3.14, MinusPlusRaw, 0), "+3");
     assert_eq!(to_string(f, -3.14, Minus, 0), "-3");
-    assert_eq!(to_string(f, -3.14, MinusRaw, 0), "-3");
+    assert_eq!(to_string(f, -3.14, Minus, 0), "-3");
     assert_eq!(to_string(f, -3.14, MinusPlus, 0), "-3");
-    assert_eq!(to_string(f, -3.14, MinusPlusRaw, 0), "-3");
     assert_eq!(to_string(f, 3.14, Minus, 1), "3.1");
-    assert_eq!(to_string(f, 3.14, MinusRaw, 2), "3.14");
-    assert_eq!(to_string(f, 3.14, MinusPlus, 3), "+3.140");
-    assert_eq!(to_string(f, 3.14, MinusPlusRaw, 4), "+3.1400");
+    assert_eq!(to_string(f, 3.14, Minus, 2), "3.14");
+    assert_eq!(to_string(f, 3.14, MinusPlus, 4), "+3.1400");
     assert_eq!(to_string(f, -3.14, Minus, 8), "-3.14000000");
-    assert_eq!(to_string(f, -3.14, MinusRaw, 8), "-3.14000000");
+    assert_eq!(to_string(f, -3.14, Minus, 8), "-3.14000000");
     assert_eq!(to_string(f, -3.14, MinusPlus, 8), "-3.14000000");
-    assert_eq!(to_string(f, -3.14, MinusPlusRaw, 8), "-3.14000000");
 
     assert_eq!(to_string(f, 0.195, Minus, 0), "0");
-    assert_eq!(to_string(f, 0.195, MinusRaw, 0), "0");
     assert_eq!(to_string(f, 0.195, MinusPlus, 0), "+0");
-    assert_eq!(to_string(f, 0.195, MinusPlusRaw, 0), "+0");
     assert_eq!(to_string(f, -0.195, Minus, 0), "-0");
-    assert_eq!(to_string(f, -0.195, MinusRaw, 0), "-0");
+    assert_eq!(to_string(f, -0.195, Minus, 0), "-0");
     assert_eq!(to_string(f, -0.195, MinusPlus, 0), "-0");
-    assert_eq!(to_string(f, -0.195, MinusPlusRaw, 0), "-0");
     assert_eq!(to_string(f, 0.195, Minus, 1), "0.2");
-    assert_eq!(to_string(f, 0.195, MinusRaw, 2), "0.20");
-    assert_eq!(to_string(f, 0.195, MinusPlus, 3), "+0.195");
-    assert_eq!(to_string(f, 0.195, MinusPlusRaw, 4), "+0.1950");
+    assert_eq!(to_string(f, 0.195, Minus, 2), "0.20");
+    assert_eq!(to_string(f, 0.195, MinusPlus, 4), "+0.1950");
     assert_eq!(to_string(f, -0.195, Minus, 5), "-0.19500");
-    assert_eq!(to_string(f, -0.195, MinusRaw, 6), "-0.195000");
-    assert_eq!(to_string(f, -0.195, MinusPlus, 7), "-0.1950000");
-    assert_eq!(to_string(f, -0.195, MinusPlusRaw, 8), "-0.19500000");
+    assert_eq!(to_string(f, -0.195, Minus, 6), "-0.195000");
+    assert_eq!(to_string(f, -0.195, MinusPlus, 8), "-0.19500000");
 
     assert_eq!(to_string(f, 999.5, Minus, 0), "1000");
     assert_eq!(to_string(f, 999.5, Minus, 1), "999.5");

diff --git a/library/core/tests/num/ieee754.rs b/library/core/tests/num/ieee754.rs
new file mode 100644
index 0000000..f6e5dfc
--- /dev/null
+++ b/library/core/tests/num/ieee754.rs

@@ -0,0 +1,158 @@
+//! IEEE 754 floating point compliance tests
+//!
+//! To understand IEEE 754's requirements on a programming language, one must understand that the
+//! requirements of IEEE 754 rest on the total programming environment, and not entirely on any
+//! one component. That means the hardware, language, and even libraries are considered part of
+//! conforming floating point support in a programming environment.
+//!
+//! A programming language's duty, accordingly, is:
+//!   1. offer access to the hardware where the hardware offers support
+//!   2. provide operations that fulfill the remaining requirements of the standard
+//!   3. provide the ability to write additional software that can fulfill those requirements
+//!
+//! This may be fulfilled in any combination that the language sees fit. However, to claim that
+//! a language supports IEEE 754 is to suggest that it has fulfilled requirements 1 and 2, without
+//! deferring minimum requirements to libraries. This is because support for IEEE 754 is defined
+//! as complete support for at least one specified floating point type as an "arithmetic" and
+//! "interchange" format, plus specified type conversions to "external character sequences" and
+//! integer types.
+//!
+//! For our purposes,
+//! "interchange format"          => f32, f64
+//! "arithmetic format"           => f32, f64, and any "soft floats"
+//! "external character sequence" => str from any float
+//! "integer format"              => {i,u}{8,16,32,64,128}
+//!
+//! None of these tests are against Rust's own implementation. They are only tests against the
+//! standard. That is why they accept wildly diverse inputs or may seem to duplicate other tests.
+//! Please consider this carefully when adding, removing, or reorganizing these tests. They are
+//! here so that it is clear what tests are required by the standard and what can be changed.
+use ::core::str::FromStr;
+
+// IEEE 754 for many tests is applied to specific bit patterns.
+// These generally are not applicable to NaN, however.
+macro_rules! assert_biteq {
+    ($lhs:expr, $rhs:expr) => {
+        assert_eq!($lhs.to_bits(), $rhs.to_bits())
+    };
+}
+
+// ToString uses the default fmt::Display impl without special concerns, and bypasses other parts
+// of the formatting infrastructure, which makes it ideal for testing here.
+#[allow(unused_macros)]
+macro_rules! roundtrip {
+    ($f:expr => $t:ty) => {
+        ($f).to_string().parse::<$t>().unwrap()
+    };
+}
+
+macro_rules! assert_floats_roundtrip {
+    ($f:ident) => {
+        assert_biteq!(f32::$f, roundtrip!(f32::$f => f32));
+        assert_biteq!(f64::$f, roundtrip!(f64::$f => f64));
+    };
+    ($f:expr) => {
+        assert_biteq!($f as f32, roundtrip!($f => f32));
+        assert_biteq!($f as f64, roundtrip!($f => f64));
+    }
+}
+
+macro_rules! assert_floats_bitne {
+    ($lhs:ident, $rhs:ident) => {
+        assert_ne!(f32::$lhs.to_bits(), f32::$rhs.to_bits());
+        assert_ne!(f64::$lhs.to_bits(), f64::$rhs.to_bits());
+    };
+    ($lhs:expr, $rhs:expr) => {
+        assert_ne!(f32::to_bits($lhs), f32::to_bits($rhs));
+        assert_ne!(f64::to_bits($lhs), f64::to_bits($rhs));
+    };
+}
+
+// We must preserve signs on all numbers. That includes zero.
+// -0 and 0 are == normally, so test bit equality.
+#[test]
+fn preserve_signed_zero() {
+    assert_floats_roundtrip!(-0.0);
+    assert_floats_roundtrip!(0.0);
+    assert_floats_bitne!(0.0, -0.0);
+}
+
+#[test]
+fn preserve_signed_infinity() {
+    assert_floats_roundtrip!(INFINITY);
+    assert_floats_roundtrip!(NEG_INFINITY);
+    assert_floats_bitne!(INFINITY, NEG_INFINITY);
+}
+
+#[test]
+fn infinity_to_str() {
+    assert!(match f32::INFINITY.to_string().to_lowercase().as_str() {
+        "+infinity" | "infinity" => true,
+        "+inf" | "inf" => true,
+        _ => false,
+    });
+    assert!(
+        match f64::INFINITY.to_string().to_lowercase().as_str() {
+            "+infinity" | "infinity" => true,
+            "+inf" | "inf" => true,
+            _ => false,
+        },
+        "Infinity must write to a string as some casing of inf or infinity, with an optional +."
+    );
+}
+
+#[test]
+fn neg_infinity_to_str() {
+    assert!(match f32::NEG_INFINITY.to_string().to_lowercase().as_str() {
+        "-infinity" | "-inf" => true,
+        _ => false,
+    });
+    assert!(
+        match f64::NEG_INFINITY.to_string().to_lowercase().as_str() {
+            "-infinity" | "-inf" => true,
+            _ => false,
+        },
+        "Negative Infinity must write to a string as some casing of -inf or -infinity"
+    )
+}
+
+#[test]
+fn nan_to_str() {
+    assert!(
+        match f32::NAN.to_string().to_lowercase().as_str() {
+            "nan" | "+nan" | "-nan" => true,
+            _ => false,
+        },
+        "NaNs must write to a string as some casing of nan."
+    )
+}
+
+// "+"?("inf"|"infinity") in any case => Infinity
+#[test]
+fn infinity_from_str() {
+    assert_biteq!(f32::INFINITY, f32::from_str("infinity").unwrap());
+    assert_biteq!(f32::INFINITY, f32::from_str("inf").unwrap());
+    assert_biteq!(f32::INFINITY, f32::from_str("+infinity").unwrap());
+    assert_biteq!(f32::INFINITY, f32::from_str("+inf").unwrap());
+    // yes! this means you are weLcOmE tO mY iNfInItElY tWiStEd MiNd
+    assert_biteq!(f32::INFINITY, f32::from_str("+iNfInItY").unwrap());
+}
+
+// "-inf"|"-infinity" in any case => Negative Infinity
+#[test]
+fn neg_infinity_from_str() {
+    assert_biteq!(f32::NEG_INFINITY, f32::from_str("-infinity").unwrap());
+    assert_biteq!(f32::NEG_INFINITY, f32::from_str("-inf").unwrap());
+    assert_biteq!(f32::NEG_INFINITY, f32::from_str("-INF").unwrap());
+    assert_biteq!(f32::NEG_INFINITY, f32::from_str("-INFinity").unwrap());
+}
+
+// ("+"|"-"")?"s"?"nan" in any case => qNaN
+#[test]
+fn qnan_from_str() {
+    assert!("nan".parse::<f32>().unwrap().is_nan());
+    assert!("-nan".parse::<f32>().unwrap().is_nan());
+    assert!("+nan".parse::<f32>().unwrap().is_nan());
+    assert!("+NAN".parse::<f32>().unwrap().is_nan());
+    assert!("-NaN".parse::<f32>().unwrap().is_nan());
+}

diff --git a/library/core/tests/num/mod.rs b/library/core/tests/num/mod.rs
index e66a73a..bbb6766 100644
--- a/library/core/tests/num/mod.rs
+++ b/library/core/tests/num/mod.rs

@@ -32,6 +32,7 @@
 mod ops;
 mod wrapping;
 
+mod ieee754;
 mod nan;
 
 /// Adds the attribute to all items in the block.

diff --git a/library/core/tests/ptr.rs b/library/core/tests/ptr.rs
index 224a58e..11af809 100644
--- a/library/core/tests/ptr.rs
+++ b/library/core/tests/ptr.rs

@@ -1,8 +1,6 @@
 use core::cell::RefCell;
-#[cfg(not(bootstrap))]
 use core::ptr;
 use core::ptr::*;
-#[cfg(not(bootstrap))]
 use std::fmt::{Debug, Display};
 
 #[test]
@@ -419,7 +417,6 @@
 }
 
 #[test]
-#[cfg(not(bootstrap))]
 fn ptr_metadata() {
     struct Unit;
     struct Pair<A, B: ?Sized>(A, B);
@@ -478,7 +475,6 @@
 }
 
 #[test]
-#[cfg(not(bootstrap))]
 fn ptr_metadata_bounds() {
     fn metadata_eq_method_address<T: ?Sized>() -> usize {
         // The `Metadata` associated type has an `Ord` bound, so this is valid:
@@ -510,7 +506,6 @@
 }
 
 #[test]
-#[cfg(not(bootstrap))]
 fn dyn_metadata() {
     #[derive(Debug)]
     #[repr(align(32))]
@@ -530,7 +525,6 @@
 }
 
 #[test]
-#[cfg(not(bootstrap))]
 fn from_raw_parts() {
     let mut value = 5_u32;
     let address = &mut value as *mut _ as *mut ();
@@ -557,7 +551,6 @@
 }
 
 #[test]
-#[cfg(not(bootstrap))]
 fn thin_box() {
     let foo = ThinBox::<dyn Display>::new(4);
     assert_eq!(foo.to_string(), "4");

diff --git a/library/core/tests/result.rs b/library/core/tests/result.rs
index 5fcd7b4..c461ab3 100644
--- a/library/core/tests/result.rs
+++ b/library/core/tests/result.rs

@@ -226,6 +226,28 @@
 }
 
 #[test]
+pub fn test_into_err() {
+    fn until_error_op() -> Result<!, isize> {
+        Err(666)
+    }
+
+    assert_eq!(until_error_op().into_err(), 666);
+
+    enum MyNeverToken {}
+    impl From<MyNeverToken> for ! {
+        fn from(never: MyNeverToken) -> ! {
+            match never {}
+        }
+    }
+
+    fn until_error_op2() -> Result<MyNeverToken, isize> {
+        Err(667)
+    }
+
+    assert_eq!(until_error_op2().into_err(), 667);
+}
+
+#[test]
 fn test_try() {
     fn try_result_some() -> Option<u8> {
         let val = Ok(1)?;

diff --git a/library/core/tests/slice.rs b/library/core/tests/slice.rs
index 7e19863..3a98cd9 100644
--- a/library/core/tests/slice.rs
+++ b/library/core/tests/slice.rs

@@ -1280,6 +1280,9 @@
             }
         )*) => {$(
             mod $case_name {
+                #[allow(unused_imports)]
+                use core::ops::Bound;
+
                 #[test]
                 fn pass() {
                     let mut v = $data;
@@ -1376,6 +1379,24 @@
             bad: data[7..=6];
             message: "out of range";
         }
+
+        in mod boundpair_len {
+            data: [0, 1, 2, 3, 4, 5];
+
+            good: data[(Bound::Included(6), Bound::Unbounded)] == [];
+            good: data[(Bound::Unbounded, Bound::Included(5))] == [0, 1, 2, 3, 4, 5];
+            good: data[(Bound::Unbounded, Bound::Excluded(6))] == [0, 1, 2, 3, 4, 5];
+            good: data[(Bound::Included(0), Bound::Included(5))] == [0, 1, 2, 3, 4, 5];
+            good: data[(Bound::Included(0), Bound::Excluded(6))] == [0, 1, 2, 3, 4, 5];
+            good: data[(Bound::Included(2), Bound::Excluded(4))] == [2, 3];
+            good: data[(Bound::Excluded(1), Bound::Included(4))] == [2, 3, 4];
+            good: data[(Bound::Excluded(5), Bound::Excluded(6))] == [];
+            good: data[(Bound::Included(6), Bound::Excluded(6))] == [];
+            good: data[(Bound::Excluded(5), Bound::Included(5))] == [];
+            good: data[(Bound::Included(6), Bound::Included(5))] == [];
+            bad: data[(Bound::Unbounded, Bound::Included(6))];
+            message: "out of range";
+        }
     }
 
     panic_cases! {
@@ -1416,6 +1437,14 @@
             bad: data[4..=2];
             message: "but ends at";
         }
+
+        in mod boundpair_neg_width {
+            data: [0, 1, 2, 3, 4, 5];
+
+            good: data[(Bound::Included(4), Bound::Excluded(4))] == [];
+            bad: data[(Bound::Included(4), Bound::Excluded(3))];
+            message: "but ends at";
+        }
     }
 
     panic_cases! {
@@ -1434,6 +1463,20 @@
             bad: data[..= usize::MAX];
             message: "maximum usize";
         }
+
+        in mod boundpair_overflow_end {
+            data: [0; 1];
+
+            bad: data[(Bound::Unbounded, Bound::Included(usize::MAX))];
+            message: "maximum usize";
+        }
+
+        in mod boundpair_overflow_start {
+            data: [0; 1];
+
+            bad: data[(Bound::Excluded(usize::MAX), Bound::Unbounded)];
+            message: "maximum usize";
+        }
     } // panic_cases!
 }