Auto merge of #18317 - lnicola:sync-from-rust, r=Veykril

minor: sync from downstream

54 files changed, 1064 insertions, 730 deletions

diff --git a/library/core/src/alloc/layout.rs b/library/core/src/alloc/layout.rs
index 107d82267e5..fca32b9d3c5 100644
--- a/library/core/src/alloc/layout.rs
+++ b/library/core/src/alloc/layout.rs
@@ -540,7 +540,8 @@ impl Layout {
 )]
 pub type LayoutErr = LayoutError;
 
-/// The parameters given to `Layout::from_size_align`
+/// The `LayoutError` is returned when the parameters given
+/// to `Layout::from_size_align`
 /// or some other `Layout` constructor
 /// do not satisfy its documented constraints.
 #[stable(feature = "alloc_layout_error", since = "1.50.0")]
diff --git a/library/core/src/arch.rs b/library/core/src/arch.rs
index 4945c045bc6..57f456c98b3 100644
--- a/library/core/src/arch.rs
+++ b/library/core/src/arch.rs
@@ -3,9 +3,6 @@
 #[allow(unused_imports)]
 #[stable(feature = "simd_arch", since = "1.27.0")]
 pub use crate::core_arch::arch::*;
-#[unstable(feature = "naked_functions", issue = "90957")]
-#[cfg(bootstrap)]
-pub use crate::naked_asm;
 
 /// Inline assembly.
 ///
@@ -28,39 +25,7 @@ pub macro asm("assembly template", $(operands,)* $(options($(option),*))?) {
 /// [Rust By Example]: https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html
 /// [reference]: https://doc.rust-lang.org/nightly/reference/inline-assembly.html
 #[unstable(feature = "naked_functions", issue = "90957")]
-#[macro_export]
-#[cfg(bootstrap)]
-macro_rules! naked_asm {
-    ([$last:expr], [$($pushed:expr),*]) => {
-        #[cfg(any(target_arch = "x86_64", target_arch = "x86"))]
-        {
-            core::arch::asm!($($pushed),*, options(att_syntax, noreturn))
-        }
-        #[cfg(not(any(target_arch = "x86_64", target_arch = "x86")))]
-        {
-            core::arch::asm!($($pushed),* , $last, options(noreturn))
-        }
-    };
-
-    ([$first:expr $(, $rest:expr)*], [$($pushed:expr),*]) => {
-        naked_asm!([$($rest),*], [$($pushed,)* $first]);
-    };
-
-    ($($expr:expr),* $(,)?) => {
-        naked_asm!([$($expr),*], []);
-    };
-}
-
-/// Inline assembly used in combination with `#[naked]` functions.
-///
-/// Refer to [Rust By Example] for a usage guide and the [reference] for
-/// detailed information about the syntax and available options.
-///
-/// [Rust By Example]: https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html
-/// [reference]: https://doc.rust-lang.org/nightly/reference/inline-assembly.html
-#[unstable(feature = "naked_functions", issue = "90957")]
 #[rustc_builtin_macro]
-#[cfg(not(bootstrap))]
 pub macro naked_asm("assembly template", $(operands,)* $(options($(option),*))?) {
     /* compiler built-in */
 }
diff --git a/library/core/src/array/ascii.rs b/library/core/src/array/ascii.rs
index 05797b042ee..e2faef855bc 100644
--- a/library/core/src/array/ascii.rs
+++ b/library/core/src/array/ascii.rs
@@ -9,7 +9,6 @@ impl<const N: usize> [u8; N] {
     ///
     /// ```
     /// #![feature(ascii_char)]
-    /// #![feature(const_option)]
     ///
     /// const HEX_DIGITS: [std::ascii::Char; 16] =
     ///     *b"0123456789abcdef".as_ascii().unwrap();
diff --git a/library/core/src/array/mod.rs b/library/core/src/array/mod.rs
index 24c42bc85dd..9b28b8b613e 100644
--- a/library/core/src/array/mod.rs
+++ b/library/core/src/array/mod.rs
@@ -146,7 +146,7 @@ pub const fn from_ref<T>(s: &T) -> &[T; 1] {
 
 /// Converts a mutable reference to `T` into a mutable reference to an array of length 1 (without copying).
 #[stable(feature = "array_from_ref", since = "1.53.0")]
-#[rustc_const_unstable(feature = "const_array_from_ref", issue = "90206")]
+#[rustc_const_stable(feature = "const_array_from_ref", since = "1.83.0")]
 pub const 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]>() }
diff --git a/library/core/src/ascii/ascii_char.rs b/library/core/src/ascii/ascii_char.rs
index ce09a0b444d..48de4f17b1b 100644
--- a/library/core/src/ascii/ascii_char.rs
+++ b/library/core/src/ascii/ascii_char.rs
@@ -506,7 +506,7 @@ impl AsciiChar {
     pub const unsafe fn digit_unchecked(d: u8) -> Self {
         assert_unsafe_precondition!(
             check_language_ub,
-            "`AsciiChar::digit_unchecked` input cannot exceed 9.",
+            "`ascii::Char::digit_unchecked` input cannot exceed 9.",
             (d: u8 = d) => d < 10
         );
 
diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs
index 95cf55a923e..e1fa43296d0 100644
--- a/library/core/src/cell.rs
+++ b/library/core/src/cell.rs
@@ -193,11 +193,11 @@
 //! use std::marker::PhantomData;
 //!
 //! struct Rc<T: ?Sized> {
-//!     ptr: NonNull<RcBox<T>>,
-//!     phantom: PhantomData<RcBox<T>>,
+//!     ptr: NonNull<RcInner<T>>,
+//!     phantom: PhantomData<RcInner<T>>,
 //! }
 //!
-//! struct RcBox<T: ?Sized> {
+//! struct RcInner<T: ?Sized> {
 //!     strong: Cell<usize>,
 //!     refcount: Cell<usize>,
 //!     value: T,
@@ -213,9 +213,9 @@
 //!     }
 //! }
 //!
-//! trait RcBoxPtr<T: ?Sized> {
+//! trait RcInnerPtr<T: ?Sized> {
 //!
-//!     fn inner(&self) -> &RcBox<T>;
+//!     fn inner(&self) -> &RcInner<T>;
 //!
 //!     fn strong(&self) -> usize {
 //!         self.inner().strong.get()
@@ -230,8 +230,8 @@
 //!     }
 //! }
 //!
-//! impl<T: ?Sized> RcBoxPtr<T> for Rc<T> {
-//!    fn inner(&self) -> &RcBox<T> {
+//! impl<T: ?Sized> RcInnerPtr<T> for Rc<T> {
+//!    fn inner(&self) -> &RcInner<T> {
 //!        unsafe {
 //!            self.ptr.as_ref()
 //!        }
@@ -515,7 +515,7 @@ impl<T> Cell<T> {
     /// assert_eq!(five, 5);
     /// ```
     #[stable(feature = "move_cell", since = "1.17.0")]
-    #[rustc_const_stable(feature = "const_cell_into_inner", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_cell_into_inner", since = "1.83.0")]
     #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
     pub const fn into_inner(self) -> T {
         self.value.into_inner()
@@ -666,7 +666,7 @@ impl<T: Default> Cell<T> {
 impl<T: CoerceUnsized<U>, U> CoerceUnsized<Cell<U>> for Cell<T> {}
 
 // Allow types that wrap `Cell` to also implement `DispatchFromDyn`
-// and become object safe method receivers.
+// and become dyn-compatible method receivers.
 // Note that currently `Cell` itself cannot be a method receiver
 // because it does not implement Deref.
 // In other words:
@@ -864,7 +864,7 @@ impl<T> RefCell<T> {
     /// let five = c.into_inner();
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_cell_into_inner", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_cell_into_inner", since = "1.83.0")]
     #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
     #[inline]
     pub const fn into_inner(self) -> T {
@@ -2108,7 +2108,7 @@ impl<T> UnsafeCell<T> {
     /// ```
     #[inline(always)]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_cell_into_inner", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_cell_into_inner", since = "1.83.0")]
     #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
     pub const fn into_inner(self) -> T {
         self.value
@@ -2181,8 +2181,7 @@ impl<T: ?Sized> UnsafeCell<T> {
     /// ```
     #[inline(always)]
     #[stable(feature = "unsafe_cell_get_mut", since = "1.50.0")]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
-    #[rustc_const_stable(feature = "const_unsafecell_get_mut", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_unsafecell_get_mut", since = "1.83.0")]
     pub const fn get_mut(&mut self) -> &mut T {
         &mut self.value
     }
@@ -2247,7 +2246,7 @@ impl<T> From<T> for UnsafeCell<T> {
 impl<T: CoerceUnsized<U>, U> CoerceUnsized<UnsafeCell<U>> for UnsafeCell<T> {}
 
 // Allow types that wrap `UnsafeCell` to also implement `DispatchFromDyn`
-// and become object safe method receivers.
+// and become dyn-compatible method receivers.
 // Note that currently `UnsafeCell` itself cannot be a method receiver
 // because it does not implement Deref.
 // In other words:
@@ -2349,7 +2348,7 @@ impl<T> From<T> for SyncUnsafeCell<T> {
 impl<T: CoerceUnsized<U>, U> CoerceUnsized<SyncUnsafeCell<U>> for SyncUnsafeCell<T> {}
 
 // Allow types that wrap `SyncUnsafeCell` to also implement `DispatchFromDyn`
-// and become object safe method receivers.
+// and become dyn-compatible method receivers.
 // Note that currently `SyncUnsafeCell` itself cannot be a method receiver
 // because it does not implement Deref.
 // In other words:
diff --git a/library/core/src/cell/lazy.rs b/library/core/src/cell/lazy.rs
index 5bc13779af9..d323fbeac9c 100644
--- a/library/core/src/cell/lazy.rs
+++ b/library/core/src/cell/lazy.rs
@@ -79,7 +79,7 @@ impl<T, F: FnOnce() -> T> LazyCell<T, F> {
     /// assert_eq!(LazyCell::into_inner(lazy).ok(), Some("HELLO, WORLD!".to_string()));
     /// ```
     #[unstable(feature = "lazy_cell_into_inner", issue = "125623")]
-    pub fn into_inner(this: Self) -> Result<T, F> {
+    pub const fn into_inner(this: Self) -> Result<T, F> {
         match this.state.into_inner() {
             State::Init(data) => Ok(data),
             State::Uninit(f) => Err(f),
@@ -306,6 +306,6 @@ impl<T: fmt::Debug, F> fmt::Debug for LazyCell<T, F> {
 
 #[cold]
 #[inline(never)]
-fn panic_poisoned() -> ! {
+const fn panic_poisoned() -> ! {
     panic!("LazyCell instance has previously been poisoned")
 }
diff --git a/library/core/src/cell/once.rs b/library/core/src/cell/once.rs
index 14c587e0c48..c14afe0f476 100644
--- a/library/core/src/cell/once.rs
+++ b/library/core/src/cell/once.rs
@@ -309,7 +309,7 @@ impl<T> OnceCell<T> {
     /// ```
     #[inline]
     #[stable(feature = "once_cell", since = "1.70.0")]
-    #[rustc_const_stable(feature = "const_cell_into_inner", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_cell_into_inner", since = "1.83.0")]
     #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
     pub const fn into_inner(self) -> Option<T> {
         // Because `into_inner` takes `self` by value, the compiler statically verifies
diff --git a/library/core/src/char/methods.rs b/library/core/src/char/methods.rs
index 7f3c998aaa5..30c0fff3104 100644
--- a/library/core/src/char/methods.rs
+++ b/library/core/src/char/methods.rs
@@ -36,7 +36,7 @@ impl char {
     /// let value_at_min = u32::from(char::MIN);
     /// assert_eq!(char::from_u32(value_at_min), Some('\0'));
     /// ```
-    #[stable(feature = "char_min", since = "CURRENT_RUSTC_VERSION")]
+    #[stable(feature = "char_min", since = "1.83.0")]
     pub const MIN: char = '\0';
 
     /// The highest valid code point a `char` can have, `'\u{10FFFF}'`.
@@ -674,7 +674,7 @@ impl char {
     /// 'ß'.encode_utf8(&mut b);
     /// ```
     #[stable(feature = "unicode_encode_char", since = "1.15.0")]
-    #[rustc_const_unstable(feature = "const_char_encode_utf8", issue = "130512")]
+    #[rustc_const_stable(feature = "const_char_encode_utf8", since = "1.83.0")]
     #[inline]
     pub const fn encode_utf8(self, dst: &mut [u8]) -> &mut str {
         // SAFETY: `char` is not a surrogate, so this is valid UTF-8.
@@ -1281,7 +1281,7 @@ impl char {
     ///
     /// [`to_ascii_uppercase()`]: #method.to_ascii_uppercase
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
-    #[rustc_const_unstable(feature = "const_make_ascii", issue = "130698")]
+    #[rustc_const_stable(feature = "const_make_ascii", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn make_ascii_uppercase(&mut self) {
         *self = self.to_ascii_uppercase();
@@ -1307,7 +1307,7 @@ impl char {
     ///
     /// [`to_ascii_lowercase()`]: #method.to_ascii_lowercase
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
-    #[rustc_const_unstable(feature = "const_make_ascii", issue = "130698")]
+    #[rustc_const_stable(feature = "const_make_ascii", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn make_ascii_lowercase(&mut self) {
         *self = self.to_ascii_lowercase();
@@ -1770,9 +1770,10 @@ const fn len_utf16(code: u32) -> usize {
 /// Panics if the buffer is not large enough.
 /// A buffer of length four is large enough to encode any `char`.
 #[unstable(feature = "char_internals", reason = "exposed only for libstd", issue = "none")]
-#[rustc_const_unstable(feature = "const_char_encode_utf8", issue = "130512")]
+#[rustc_const_stable(feature = "const_char_encode_utf8", since = "1.83.0")]
 #[doc(hidden)]
 #[inline]
+#[rustc_allow_const_fn_unstable(const_eval_select)]
 pub const fn encode_utf8_raw(code: u32, dst: &mut [u8]) -> &mut [u8] {
     const fn panic_at_const(_code: u32, _len: usize, _dst_len: usize) {
         // Note that we cannot format in constant expressions.
diff --git a/library/core/src/error.rs b/library/core/src/error.rs
index cac00b37d1f..95a39cc3aed 100644
--- a/library/core/src/error.rs
+++ b/library/core/src/error.rs
@@ -335,16 +335,17 @@ impl dyn Error {
     #[unstable(feature = "error_iter", issue = "58520")]
     #[inline]
     pub fn sources(&self) -> Source<'_> {
-        // You may think this method would be better in the Error trait, and you'd be right.
-        // Unfortunately that doesn't work, not because of the object safety rules but because we
-        // save a reference to self in Sources below as a trait object. If this method was
-        // declared in Error, then self would have the type &T where T is some concrete type which
-        // implements Error. We would need to coerce self to have type &dyn Error, but that requires
-        // that Self has a known size (i.e., Self: Sized). We can't put that bound on Error
-        // since that would forbid Error trait objects, and we can't put that bound on the method
-        // because that means the method can't be called on trait objects (we'd also need the
-        // 'static bound, but that isn't allowed because methods with bounds on Self other than
-        // Sized are not object-safe). Requiring an Unsize bound is not backwards compatible.
+        // You may think this method would be better in the `Error` trait, and you'd be right.
+        // Unfortunately that doesn't work, not because of the dyn-incompatibility rules but
+        // because we save a reference to `self` in `Source`s below as a trait object.
+        // If this method was declared in `Error`, then `self` would have the type `&T` where
+        // `T` is some concrete type which implements `Error`. We would need to coerce `self`
+        // to have type `&dyn Error`, but that requires that `Self` has a known size
+        // (i.e., `Self: Sized`). We can't put that bound on `Error` since that would forbid
+        // `Error` trait objects, and we can't put that bound on the method because that means
+        // the method can't be called on trait objects (we'd also need the `'static` bound,
+        // but that isn't allowed because methods with bounds on `Self` other than `Sized` are
+        // dyn-incompatible). Requiring an `Unsize` bound is not backwards compatible.
 
         Source { current: Some(self) }
     }
diff --git a/library/core/src/escape.rs b/library/core/src/escape.rs
index b213cc2b916..0685f525dca 100644
--- a/library/core/src/escape.rs
+++ b/library/core/src/escape.rs
@@ -18,38 +18,106 @@ const fn backslash<const N: usize>(a: ascii::Char) -> ([ascii::Char; N], Range<u
     (output, 0..2)
 }
 
+#[inline]
+const fn hex_escape<const N: usize>(byte: u8) -> ([ascii::Char; N], Range<u8>) {
+    const { assert!(N >= 4) };
+
+    let mut output = [ascii::Char::Null; N];
+
+    let hi = HEX_DIGITS[(byte >> 4) as usize];
+    let lo = HEX_DIGITS[(byte & 0xf) as usize];
+
+    output[0] = ascii::Char::ReverseSolidus;
+    output[1] = ascii::Char::SmallX;
+    output[2] = hi;
+    output[3] = lo;
+
+    (output, 0..4)
+}
+
+#[inline]
+const fn verbatim<const N: usize>(a: ascii::Char) -> ([ascii::Char; N], Range<u8>) {
+    const { assert!(N >= 1) };
+
+    let mut output = [ascii::Char::Null; N];
+
+    output[0] = a;
+
+    (output, 0..1)
+}
+
 /// Escapes an ASCII character.
 ///
 /// Returns a buffer and the length of the escaped representation.
 const fn escape_ascii<const N: usize>(byte: u8) -> ([ascii::Char; N], Range<u8>) {
     const { assert!(N >= 4) };
 
-    match byte {
-        b'\t' => backslash(ascii::Char::SmallT),
-        b'\r' => backslash(ascii::Char::SmallR),
-        b'\n' => backslash(ascii::Char::SmallN),
-        b'\\' => backslash(ascii::Char::ReverseSolidus),
-        b'\'' => backslash(ascii::Char::Apostrophe),
-        b'\"' => backslash(ascii::Char::QuotationMark),
-        byte => {
-            let mut output = [ascii::Char::Null; N];
-
-            if let Some(c) = byte.as_ascii()
-                && !byte.is_ascii_control()
-            {
-                output[0] = c;
-                (output, 0..1)
-            } else {
-                let hi = HEX_DIGITS[(byte >> 4) as usize];
-                let lo = HEX_DIGITS[(byte & 0xf) as usize];
+    #[cfg(feature = "optimize_for_size")]
+    {
+        match byte {
+            b'\t' => backslash(ascii::Char::SmallT),
+            b'\r' => backslash(ascii::Char::SmallR),
+            b'\n' => backslash(ascii::Char::SmallN),
+            b'\\' => backslash(ascii::Char::ReverseSolidus),
+            b'\'' => backslash(ascii::Char::Apostrophe),
+            b'"' => backslash(ascii::Char::QuotationMark),
+            0x00..=0x1F | 0x7F => hex_escape(byte),
+            _ => match ascii::Char::from_u8(byte) {
+                Some(a) => verbatim(a),
+                None => hex_escape(byte),
+            },
+        }
+    }
+
+    #[cfg(not(feature = "optimize_for_size"))]
+    {
+        /// Lookup table helps us determine how to display character.
+        ///
+        /// Since ASCII characters will always be 7 bits, we can exploit this to store the 8th bit to
+        /// indicate whether the result is escaped or unescaped.
+        ///
+        /// We additionally use 0x80 (escaped NUL character) to indicate hex-escaped bytes, since
+        /// escaped NUL will not occur.
+        const LOOKUP: [u8; 256] = {
+            let mut arr = [0; 256];
+            let mut idx = 0;
+            while idx <= 255 {
+                arr[idx] = match idx as u8 {
+                    // use 8th bit to indicate escaped
+                    b'\t' => 0x80 | b't',
+                    b'\r' => 0x80 | b'r',
+                    b'\n' => 0x80 | b'n',
+                    b'\\' => 0x80 | b'\\',
+                    b'\'' => 0x80 | b'\'',
+                    b'"' => 0x80 | b'"',
+
+                    // use NUL to indicate hex-escaped
+                    0x00..=0x1F | 0x7F..=0xFF => 0x80 | b'\0',
+
+                    idx => idx,
+                };
+                idx += 1;
+            }
+            arr
+        };
 
-                output[0] = ascii::Char::ReverseSolidus;
-                output[1] = ascii::Char::SmallX;
-                output[2] = hi;
-                output[3] = lo;
+        let lookup = LOOKUP[byte as usize];
 
-                (output, 0..4)
+        // 8th bit indicates escape
+        let lookup_escaped = lookup & 0x80 != 0;
+
+        // SAFETY: We explicitly mask out the eighth bit to get a 7-bit ASCII character.
+        let lookup_ascii = unsafe { ascii::Char::from_u8_unchecked(lookup & 0x7F) };
+
+        if lookup_escaped {
+            // NUL indicates hex-escaped
+            if matches!(lookup_ascii, ascii::Char::Null) {
+                hex_escape(byte)
+            } else {
+                backslash(lookup_ascii)
             }
+        } else {
+            verbatim(lookup_ascii)
         }
     }
 }
diff --git a/library/core/src/fmt/builders.rs b/library/core/src/fmt/builders.rs
index c7c462a4df1..1862be0e86c 100644
--- a/library/core/src/fmt/builders.rs
+++ b/library/core/src/fmt/builders.rs
@@ -366,8 +366,6 @@ impl<'a, 'b: 'a> DebugTuple<'a, 'b> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(debug_more_non_exhaustive)]
-    ///
     /// use std::fmt;
     ///
     /// struct Foo(i32, String);
@@ -385,7 +383,7 @@ impl<'a, 'b: 'a> DebugTuple<'a, 'b> {
     ///     "Foo(10, ..)",
     /// );
     /// ```
-    #[unstable(feature = "debug_more_non_exhaustive", issue = "127942")]
+    #[stable(feature = "debug_more_non_exhaustive", since = "1.83.0")]
     pub fn finish_non_exhaustive(&mut self) -> fmt::Result {
         self.result = self.result.and_then(|_| {
             if self.fields > 0 {
@@ -606,8 +604,6 @@ impl<'a, 'b: 'a> DebugSet<'a, 'b> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(debug_more_non_exhaustive)]
-    ///
     /// use std::fmt;
     ///
     /// struct Foo(Vec<i32>);
@@ -630,7 +626,7 @@ impl<'a, 'b: 'a> DebugSet<'a, 'b> {
     ///     "{1, 2, ..}",
     /// );
     /// ```
-    #[unstable(feature = "debug_more_non_exhaustive", issue = "127942")]
+    #[stable(feature = "debug_more_non_exhaustive", since = "1.83.0")]
     pub fn finish_non_exhaustive(&mut self) -> fmt::Result {
         self.inner.result = self.inner.result.and_then(|_| {
             if self.inner.has_fields {
@@ -800,8 +796,6 @@ impl<'a, 'b: 'a> DebugList<'a, 'b> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(debug_more_non_exhaustive)]
-    ///
     /// use std::fmt;
     ///
     /// struct Foo(Vec<i32>);
@@ -824,7 +818,7 @@ impl<'a, 'b: 'a> DebugList<'a, 'b> {
     ///     "[1, 2, ..]",
     /// );
     /// ```
-    #[unstable(feature = "debug_more_non_exhaustive", issue = "127942")]
+    #[stable(feature = "debug_more_non_exhaustive", since = "1.83.0")]
     pub fn finish_non_exhaustive(&mut self) -> fmt::Result {
         self.inner.result.and_then(|_| {
             if self.inner.has_fields {
@@ -1126,8 +1120,6 @@ impl<'a, 'b: 'a> DebugMap<'a, 'b> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(debug_more_non_exhaustive)]
-    ///
     /// use std::fmt;
     ///
     /// struct Foo(Vec<(String, i32)>);
@@ -1154,7 +1146,7 @@ impl<'a, 'b: 'a> DebugMap<'a, 'b> {
     ///     r#"{"A": 10, "B": 11, ..}"#,
     /// );
     /// ```
-    #[unstable(feature = "debug_more_non_exhaustive", issue = "127942")]
+    #[stable(feature = "debug_more_non_exhaustive", since = "1.83.0")]
     pub fn finish_non_exhaustive(&mut self) -> fmt::Result {
         self.result = self.result.and_then(|_| {
             assert!(!self.has_key, "attempted to finish a map with a partial entry");
diff --git a/library/core/src/fmt/float.rs b/library/core/src/fmt/float.rs
index 20ea0352c2d..c70dbf54304 100644
--- a/library/core/src/fmt/float.rs
+++ b/library/core/src/fmt/float.rs
@@ -196,39 +196,40 @@ where
 }
 
 macro_rules! floating {
-    ($ty:ident) => {
-        #[stable(feature = "rust1", since = "1.0.0")]
-        impl Debug for $ty {
-            fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
-                float_to_general_debug(fmt, self)
+    ($($ty:ident)*) => {
+        $(
+            #[stable(feature = "rust1", since = "1.0.0")]
+            impl Debug for $ty {
+                fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
+                    float_to_general_debug(fmt, self)
+                }
             }
-        }
 
-        #[stable(feature = "rust1", since = "1.0.0")]
-        impl Display for $ty {
-            fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
-                float_to_decimal_display(fmt, self)
+            #[stable(feature = "rust1", since = "1.0.0")]
+            impl Display for $ty {
+                fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
+                    float_to_decimal_display(fmt, self)
+                }
             }
-        }
 
-        #[stable(feature = "rust1", since = "1.0.0")]
-        impl LowerExp for $ty {
-            fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
-                float_to_exponential_common(fmt, self, false)
+            #[stable(feature = "rust1", since = "1.0.0")]
+            impl LowerExp for $ty {
+                fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
+                    float_to_exponential_common(fmt, self, false)
+                }
             }
-        }
 
-        #[stable(feature = "rust1", since = "1.0.0")]
-        impl UpperExp for $ty {
-            fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
-                float_to_exponential_common(fmt, self, true)
+            #[stable(feature = "rust1", since = "1.0.0")]
+            impl UpperExp for $ty {
+                fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
+                    float_to_exponential_common(fmt, self, true)
+                }
             }
-        }
+        )*
     };
 }
 
-floating! { f32 }
-floating! { f64 }
+floating! { f32 f64 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Debug for f16 {
diff --git a/library/core/src/fmt/nofloat.rs b/library/core/src/fmt/nofloat.rs
index 6b07236f1da..29aaee75d22 100644
--- a/library/core/src/fmt/nofloat.rs
+++ b/library/core/src/fmt/nofloat.rs
@@ -1,18 +1,17 @@
 use crate::fmt::{Debug, Formatter, Result};
 
 macro_rules! floating {
-    ($ty:ident) => {
-        #[stable(feature = "rust1", since = "1.0.0")]
-        impl Debug for $ty {
-            #[inline]
-            fn fmt(&self, _fmt: &mut Formatter<'_>) -> Result {
-                panic!("floating point support is turned off");
+    ($($ty:ident)*) => {
+        $(
+            #[stable(feature = "rust1", since = "1.0.0")]
+            impl Debug for $ty {
+                #[inline]
+                fn fmt(&self, _fmt: &mut Formatter<'_>) -> Result {
+                    panic!("floating point fmt support is turned off");
+                }
             }
-        }
+        )*
     };
 }
 
-floating! { f16 }
-floating! { f32 }
-floating! { f64 }
-floating! { f128 }
+floating! { f16 f32 f64 f128 }
diff --git a/library/core/src/fmt/num.rs b/library/core/src/fmt/num.rs
index aecd725eca5..f1540803f97 100644
--- a/library/core/src/fmt/num.rs
+++ b/library/core/src/fmt/num.rs
@@ -20,33 +20,22 @@ trait DisplayInt:
 
 macro_rules! impl_int {
     ($($t:ident)*) => (
-      $(impl DisplayInt for $t {
-          fn zero() -> Self { 0 }
-          fn from_u8(u: u8) -> Self { u as Self }
-          fn to_u8(&self) -> u8 { *self as u8 }
-          #[cfg(not(any(target_pointer_width = "64", target_arch = "wasm32")))]
-          fn to_u32(&self) -> u32 { *self as u32 }
-          fn to_u64(&self) -> u64 { *self as u64 }
-          fn to_u128(&self) -> u128 { *self as u128 }
-      })*
-    )
-}
-macro_rules! impl_uint {
-    ($($t:ident)*) => (
-      $(impl DisplayInt for $t {
-          fn zero() -> Self { 0 }
-          fn from_u8(u: u8) -> Self { u as Self }
-          fn to_u8(&self) -> u8 { *self as u8 }
-          #[cfg(not(any(target_pointer_width = "64", target_arch = "wasm32")))]
-          fn to_u32(&self) -> u32 { *self as u32 }
-          fn to_u64(&self) -> u64 { *self as u64 }
-          fn to_u128(&self) -> u128 { *self as u128 }
-      })*
+        $(impl DisplayInt for $t {
+            fn zero() -> Self { 0 }
+            fn from_u8(u: u8) -> Self { u as Self }
+            fn to_u8(&self) -> u8 { *self as u8 }
+            #[cfg(not(any(target_pointer_width = "64", target_arch = "wasm32")))]
+            fn to_u32(&self) -> u32 { *self as u32 }
+            fn to_u64(&self) -> u64 { *self as u64 }
+            fn to_u128(&self) -> u128 { *self as u128 }
+        })*
     )
 }
 
-impl_int! { i8 i16 i32 i64 i128 isize }
-impl_uint! { u8 u16 u32 u64 u128 usize }
+impl_int! {
+    i8 i16 i32 i64 i128 isize
+    u8 u16 u32 u64 u128 usize
+}
 
 /// A type that represents a specific radix
 ///
@@ -178,26 +167,25 @@ integer! { i16, u16 }
 integer! { i32, u32 }
 integer! { i64, u64 }
 integer! { i128, u128 }
-macro_rules! debug {
-    ($($T:ident)*) => {$(
-        #[stable(feature = "rust1", since = "1.0.0")]
-        impl fmt::Debug for $T {
-            #[inline]
-            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-                if f.debug_lower_hex() {
-                    fmt::LowerHex::fmt(self, f)
-                } else if f.debug_upper_hex() {
-                    fmt::UpperHex::fmt(self, f)
-                } else {
-                    fmt::Display::fmt(self, f)
+
+macro_rules! impl_Debug {
+    ($($T:ident)*) => {
+        $(
+            #[stable(feature = "rust1", since = "1.0.0")]
+            impl fmt::Debug for $T {
+                #[inline]
+                fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    if f.debug_lower_hex() {
+                        fmt::LowerHex::fmt(self, f)
+                    } else if f.debug_upper_hex() {
+                        fmt::UpperHex::fmt(self, f)
+                    } else {
+                        fmt::Display::fmt(self, f)
+                    }
                 }
             }
-        }
-    )*};
-}
-debug! {
-  i8 i16 i32 i64 i128 isize
-  u8 u16 u32 u64 u128 usize
+        )*
+    };
 }
 
 // 2 digit decimal look up table
@@ -521,6 +509,11 @@ macro_rules! impl_Exp {
     };
 }
 
+impl_Debug! {
+    i8 i16 i32 i64 i128 isize
+    u8 u16 u32 u64 u128 usize
+}
+
 // Include wasm32 in here since it doesn't reflect the native pointer size, and
 // often cares strongly about getting a smaller code size.
 #[cfg(any(target_pointer_width = "64", target_arch = "wasm32"))]
diff --git a/library/core/src/intrinsics.rs b/library/core/src/intrinsics.rs
index d7a2f1909ca..69ad4f41519 100644
--- a/library/core/src/intrinsics.rs
+++ b/library/core/src/intrinsics.rs
@@ -64,6 +64,7 @@
 #![allow(missing_docs)]
 
 use crate::marker::{DiscriminantKind, Tuple};
+use crate::mem::SizedTypeProperties;
 use crate::{ptr, ub_checks};
 
 pub mod mir;
@@ -1084,7 +1085,7 @@ extern "rust-intrinsic" {
     /// it does not require an `unsafe` block.
     /// Therefore, implementations must not require the user to uphold
     /// any safety invariants.
-    #[rustc_const_unstable(feature = "const_intrinsic_forget", issue = "none")]
+    #[rustc_const_stable(feature = "const_intrinsic_forget", since = "1.83.0")]
     #[rustc_safe_intrinsic]
     #[rustc_nounwind]
     pub fn forget<T: ?Sized>(_: T);
@@ -1795,153 +1796,54 @@ extern "rust-intrinsic" {
     #[rustc_nounwind]
     pub fn fmaf128(a: f128, b: f128, c: f128) -> f128;
 
-    /// Returns the absolute value of an `f16`.
-    ///
-    /// The stabilized version of this intrinsic is
-    /// [`f16::abs`](../../std/primitive.f16.html#method.abs)
-    #[rustc_nounwind]
-    pub fn fabsf16(x: f16) -> f16;
-    /// Returns the absolute value of an `f32`.
-    ///
-    /// The stabilized version of this intrinsic is
-    /// [`f32::abs`](../../std/primitive.f32.html#method.abs)
-    #[rustc_nounwind]
-    pub fn fabsf32(x: f32) -> f32;
-    /// Returns the absolute value of an `f64`.
-    ///
-    /// The stabilized version of this intrinsic is
-    /// [`f64::abs`](../../std/primitive.f64.html#method.abs)
-    #[rustc_nounwind]
-    pub fn fabsf64(x: f64) -> f64;
-    /// Returns the absolute value of an `f128`.
-    ///
-    /// The stabilized version of this intrinsic is
-    /// [`f128::abs`](../../std/primitive.f128.html#method.abs)
-    #[rustc_nounwind]
-    pub fn fabsf128(x: f128) -> f128;
-
-    /// Returns the minimum of two `f16` values.
-    ///
-    /// Note that, unlike most intrinsics, this is safe to call;
-    /// it does not require an `unsafe` block.
-    /// Therefore, implementations must not require the user to uphold
-    /// any safety invariants.
-    ///
-    /// The stabilized version of this intrinsic is
-    /// [`f16::min`]
-    #[rustc_safe_intrinsic]
-    #[rustc_nounwind]
-    pub fn minnumf16(x: f16, y: f16) -> f16;
-    /// Returns the minimum of two `f32` values.
-    ///
-    /// Note that, unlike most intrinsics, this is safe to call;
-    /// it does not require an `unsafe` block.
-    /// Therefore, implementations must not require the user to uphold
-    /// any safety invariants.
-    ///
-    /// The stabilized version of this intrinsic is
-    /// [`f32::min`]
-    #[rustc_safe_intrinsic]
-    #[rustc_nounwind]
-    pub fn minnumf32(x: f32, y: f32) -> f32;
-    /// Returns the minimum of two `f64` values.
-    ///
-    /// Note that, unlike most intrinsics, this is safe to call;
-    /// it does not require an `unsafe` block.
-    /// Therefore, implementations must not require the user to uphold
-    /// any safety invariants.
-    ///
-    /// The stabilized version of this intrinsic is
-    /// [`f64::min`]
-    #[rustc_safe_intrinsic]
-    #[rustc_nounwind]
-    pub fn minnumf64(x: f64, y: f64) -> f64;
-    /// Returns the minimum of two `f128` values.
-    ///
-    /// Note that, unlike most intrinsics, this is safe to call;
-    /// it does not require an `unsafe` block.
-    /// Therefore, implementations must not require the user to uphold
-    /// any safety invariants.
-    ///
-    /// The stabilized version of this intrinsic is
-    /// [`f128::min`]
-    #[rustc_safe_intrinsic]
-    #[rustc_nounwind]
-    pub fn minnumf128(x: f128, y: f128) -> f128;
-
-    /// Returns the maximum of two `f16` values.
-    ///
-    /// Note that, unlike most intrinsics, this is safe to call;
-    /// it does not require an `unsafe` block.
-    /// Therefore, implementations must not require the user to uphold
-    /// any safety invariants.
-    ///
-    /// The stabilized version of this intrinsic is
-    /// [`f16::max`]
-    #[rustc_safe_intrinsic]
-    #[rustc_nounwind]
-    pub fn maxnumf16(x: f16, y: f16) -> f16;
-    /// Returns the maximum of two `f32` values.
-    ///
-    /// Note that, unlike most intrinsics, this is safe to call;
-    /// it does not require an `unsafe` block.
-    /// Therefore, implementations must not require the user to uphold
-    /// any safety invariants.
-    ///
-    /// The stabilized version of this intrinsic is
-    /// [`f32::max`]
-    #[rustc_safe_intrinsic]
-    #[rustc_nounwind]
-    pub fn maxnumf32(x: f32, y: f32) -> f32;
-    /// Returns the maximum of two `f64` values.
-    ///
-    /// Note that, unlike most intrinsics, this is safe to call;
-    /// it does not require an `unsafe` block.
-    /// Therefore, implementations must not require the user to uphold
-    /// any safety invariants.
-    ///
-    /// The stabilized version of this intrinsic is
-    /// [`f64::max`]
-    #[rustc_safe_intrinsic]
-    #[rustc_nounwind]
-    pub fn maxnumf64(x: f64, y: f64) -> f64;
-    /// Returns the maximum of two `f128` values.
-    ///
-    /// Note that, unlike most intrinsics, this is safe to call;
-    /// it does not require an `unsafe` block.
-    /// Therefore, implementations must not require the user to uphold
-    /// any safety invariants.
-    ///
-    /// The stabilized version of this intrinsic is
-    /// [`f128::max`]
-    #[rustc_safe_intrinsic]
-    #[rustc_nounwind]
-    pub fn maxnumf128(x: f128, y: f128) -> f128;
-
-    /// Copies the sign from `y` to `x` for `f16` values.
-    ///
-    /// The stabilized version of this intrinsic is
-    /// [`f16::copysign`](../../std/primitive.f16.html#method.copysign)
-    #[rustc_nounwind]
-    pub fn copysignf16(x: f16, y: f16) -> f16;
-    /// Copies the sign from `y` to `x` for `f32` values.
-    ///
-    /// The stabilized version of this intrinsic is
-    /// [`f32::copysign`](../../std/primitive.f32.html#method.copysign)
-    #[rustc_nounwind]
-    pub fn copysignf32(x: f32, y: f32) -> f32;
-    /// Copies the sign from `y` to `x` for `f64` values.
-    ///
-    /// The stabilized version of this intrinsic is
-    /// [`f64::copysign`](../../std/primitive.f64.html#method.copysign)
-    #[rustc_nounwind]
-    pub fn copysignf64(x: f64, y: f64) -> f64;
-    /// Copies the sign from `y` to `x` for `f128` values.
-    ///
-    /// The stabilized version of this intrinsic is
-    /// [`f128::copysign`](../../std/primitive.f128.html#method.copysign)
-    #[rustc_nounwind]
-    pub fn copysignf128(x: f128, y: f128) -> f128;
+    /// Returns `a * b + c` for `f16` values, non-deterministically executing
+    /// either a fused multiply-add or two operations with rounding of the
+    /// intermediate result.
+    ///
+    /// The operation is fused if the code generator determines that target
+    /// instruction set has support for a fused operation, and that the fused
+    /// operation is more efficient than the equivalent, separate pair of mul
+    /// and add instructions. It is unspecified whether or not a fused operation
+    /// is selected, and that may depend on optimization level and context, for
+    /// example.
+    #[rustc_nounwind]
+    pub fn fmuladdf16(a: f16, b: f16, c: f16) -> f16;
+    /// Returns `a * b + c` for `f32` values, non-deterministically executing
+    /// either a fused multiply-add or two operations with rounding of the
+    /// intermediate result.
+    ///
+    /// The operation is fused if the code generator determines that target
+    /// instruction set has support for a fused operation, and that the fused
+    /// operation is more efficient than the equivalent, separate pair of mul
+    /// and add instructions. It is unspecified whether or not a fused operation
+    /// is selected, and that may depend on optimization level and context, for
+    /// example.
+    #[rustc_nounwind]
+    pub fn fmuladdf32(a: f32, b: f32, c: f32) -> f32;
+    /// Returns `a * b + c` for `f64` values, non-deterministically executing
+    /// either a fused multiply-add or two operations with rounding of the
+    /// intermediate result.
+    ///
+    /// The operation is fused if the code generator determines that target
+    /// instruction set has support for a fused operation, and that the fused
+    /// operation is more efficient than the equivalent, separate pair of mul
+    /// and add instructions. It is unspecified whether or not a fused operation
+    /// is selected, and that may depend on optimization level and context, for
+    /// example.
+    #[rustc_nounwind]
+    pub fn fmuladdf64(a: f64, b: f64, c: f64) -> f64;
+    /// Returns `a * b + c` for `f128` values, non-deterministically executing
+    /// either a fused multiply-add or two operations with rounding of the
+    /// intermediate result.
+    ///
+    /// The operation is fused if the code generator determines that target
+    /// instruction set has support for a fused operation, and that the fused
+    /// operation is more efficient than the equivalent, separate pair of mul
+    /// and add instructions. It is unspecified whether or not a fused operation
+    /// is selected, and that may depend on optimization level and context, for
+    /// example.
+    #[rustc_nounwind]
+    pub fn fmuladdf128(a: f128, b: f128, c: f128) -> f128;
 
     /// Returns the largest integer less than or equal to an `f16`.
     ///
@@ -2635,7 +2537,7 @@ extern "rust-intrinsic" {
     /// This intrinsic can *only* be called where the pointer is a local without
     /// projections (`write_via_move(ptr, x)`, not `write_via_move(*ptr, x)`) so
     /// that it trivially obeys runtime-MIR rules about derefs in operands.
-    #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[rustc_const_stable(feature = "const_ptr_write", since = "1.83.0")]
     #[rustc_nounwind]
     pub fn write_via_move<T>(ptr: *mut T, value: T);
 
@@ -3164,7 +3066,7 @@ pub const fn type_id<T: ?Sized + 'static>() -> u128 {
 /// change the possible layouts of pointers.
 #[rustc_nounwind]
 #[unstable(feature = "core_intrinsics", issue = "none")]
-#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
+#[rustc_const_stable(feature = "ptr_metadata_const", since = "1.83.0")]
 #[rustc_intrinsic]
 #[rustc_intrinsic_must_be_overridden]
 pub const fn aggregate_raw_ptr<P: AggregateRawPtr<D, Metadata = M>, D, M>(_data: D, _meta: M) -> P {
@@ -3189,7 +3091,7 @@ impl<P: ?Sized, T: ptr::Thin> AggregateRawPtr<*mut T> for *mut P {
 /// This is used to implement functions like `ptr::metadata`.
 #[rustc_nounwind]
 #[unstable(feature = "core_intrinsics", issue = "none")]
-#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
+#[rustc_const_stable(feature = "ptr_metadata_const", since = "1.83.0")]
 #[rustc_intrinsic]
 #[rustc_intrinsic_must_be_overridden]
 pub const fn ptr_metadata<P: ptr::Pointee<Metadata = M> + ?Sized, M>(_ptr: *const P) -> M {
@@ -3290,13 +3192,13 @@ pub const fn ptr_metadata<P: ptr::Pointee<Metadata = M> + ?Sized, M>(_ptr: *cons
 #[doc(alias = "memcpy")]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_allowed_through_unstable_modules]
-#[rustc_const_stable(feature = "const_intrinsic_copy", since = "CURRENT_RUSTC_VERSION")]
+#[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.83.0")]
 #[inline(always)]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 #[rustc_diagnostic_item = "ptr_copy_nonoverlapping"]
 pub const unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize) {
     extern "rust-intrinsic" {
-        #[rustc_const_stable(feature = "const_intrinsic_copy", since = "CURRENT_RUSTC_VERSION")]
+        #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.83.0")]
         #[rustc_nounwind]
         pub fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize);
     }
@@ -3311,10 +3213,12 @@ pub const unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: us
             size: usize = size_of::<T>(),
             align: usize = align_of::<T>(),
             count: usize = count,
-        ) =>
-        ub_checks::is_aligned_and_not_null(src, align)
-            && ub_checks::is_aligned_and_not_null(dst, align)
-            && ub_checks::is_nonoverlapping(src, dst, size, count)
+        ) => {
+            let zero_size = count == 0 || size == 0;
+            ub_checks::is_aligned_and_not_null(src, align, zero_size)
+                && ub_checks::is_aligned_and_not_null(dst, align, zero_size)
+                && ub_checks::is_nonoverlapping(src, dst, size, count)
+        }
     );
 
     // SAFETY: the safety contract for `copy_nonoverlapping` must be
@@ -3392,13 +3296,13 @@ pub const unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: us
 #[doc(alias = "memmove")]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_allowed_through_unstable_modules]
-#[rustc_const_stable(feature = "const_intrinsic_copy", since = "CURRENT_RUSTC_VERSION")]
+#[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.83.0")]
 #[inline(always)]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 #[rustc_diagnostic_item = "ptr_copy"]
 pub const unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
     extern "rust-intrinsic" {
-        #[rustc_const_stable(feature = "const_intrinsic_copy", since = "CURRENT_RUSTC_VERSION")]
+        #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.83.0")]
         #[rustc_nounwind]
         fn copy<T>(src: *const T, dst: *mut T, count: usize);
     }
@@ -3412,9 +3316,10 @@ pub const unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
                 src: *const () = src as *const (),
                 dst: *mut () = dst as *mut (),
                 align: usize = align_of::<T>(),
+                zero_size: bool = T::IS_ZST || count == 0,
             ) =>
-            ub_checks::is_aligned_and_not_null(src, align)
-                && ub_checks::is_aligned_and_not_null(dst, align)
+            ub_checks::is_aligned_and_not_null(src, align, zero_size)
+                && ub_checks::is_aligned_and_not_null(dst, align, zero_size)
         );
         copy(src, dst, count)
     }
@@ -3472,13 +3377,13 @@ pub const unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
 #[doc(alias = "memset")]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_allowed_through_unstable_modules]
-#[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+#[rustc_const_stable(feature = "const_ptr_write", since = "1.83.0")]
 #[inline(always)]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 #[rustc_diagnostic_item = "ptr_write_bytes"]
 pub const unsafe fn write_bytes<T>(dst: *mut T, val: u8, count: usize) {
     extern "rust-intrinsic" {
-        #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+        #[rustc_const_stable(feature = "const_ptr_write", since = "1.83.0")]
         #[rustc_nounwind]
         fn write_bytes<T>(dst: *mut T, val: u8, count: usize);
     }
@@ -3491,12 +3396,252 @@ pub const unsafe fn write_bytes<T>(dst: *mut T, val: u8, count: usize) {
             (
                 addr: *const () = dst as *const (),
                 align: usize = align_of::<T>(),
-            ) => ub_checks::is_aligned_and_not_null(addr, align)
+                zero_size: bool = T::IS_ZST || count == 0,
+            ) => ub_checks::is_aligned_and_not_null(addr, align, zero_size)
         );
         write_bytes(dst, val, count)
     }
 }
 
+/// Returns the minimum of two `f16` values.
+///
+/// Note that, unlike most intrinsics, this is safe to call;
+/// it does not require an `unsafe` block.
+/// Therefore, implementations must not require the user to uphold
+/// any safety invariants.
+///
+/// The stabilized version of this intrinsic is
+/// [`f16::min`]
+#[rustc_nounwind]
+// #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+#[rustc_const_unstable(feature = "f16", issue = "116909")]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const fn minnumf16(_x: f16, _y: f16) -> f16 {
+    unimplemented!();
+}
+
+/// Returns the minimum of two `f32` values.
+///
+/// Note that, unlike most intrinsics, this is safe to call;
+/// it does not require an `unsafe` block.
+/// Therefore, implementations must not require the user to uphold
+/// any safety invariants.
+///
+/// The stabilized version of this intrinsic is
+/// [`f32::min`]
+#[rustc_nounwind]
+#[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const fn minnumf32(_x: f32, _y: f32) -> f32 {
+    unimplemented!();
+}
+
+/// Returns the minimum of two `f64` values.
+///
+/// Note that, unlike most intrinsics, this is safe to call;
+/// it does not require an `unsafe` block.
+/// Therefore, implementations must not require the user to uphold
+/// any safety invariants.
+///
+/// The stabilized version of this intrinsic is
+/// [`f64::min`]
+#[rustc_nounwind]
+#[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const fn minnumf64(_x: f64, _y: f64) -> f64 {
+    unimplemented!();
+}
+
+/// Returns the minimum of two `f128` values.
+///
+/// Note that, unlike most intrinsics, this is safe to call;
+/// it does not require an `unsafe` block.
+/// Therefore, implementations must not require the user to uphold
+/// any safety invariants.
+///
+/// The stabilized version of this intrinsic is
+/// [`f128::min`]
+#[rustc_nounwind]
+// #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+#[rustc_const_unstable(feature = "f128", issue = "116909")]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const fn minnumf128(_x: f128, _y: f128) -> f128 {
+    unimplemented!();
+}
+
+/// Returns the maximum of two `f16` values.
+///
+/// Note that, unlike most intrinsics, this is safe to call;
+/// it does not require an `unsafe` block.
+/// Therefore, implementations must not require the user to uphold
+/// any safety invariants.
+///
+/// The stabilized version of this intrinsic is
+/// [`f16::max`]
+#[rustc_nounwind]
+// #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+#[rustc_const_unstable(feature = "f16", issue = "116909")]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const fn maxnumf16(_x: f16, _y: f16) -> f16 {
+    unimplemented!();
+}
+
+/// Returns the maximum of two `f32` values.
+///
+/// Note that, unlike most intrinsics, this is safe to call;
+/// it does not require an `unsafe` block.
+/// Therefore, implementations must not require the user to uphold
+/// any safety invariants.
+///
+/// The stabilized version of this intrinsic is
+/// [`f32::max`]
+#[rustc_nounwind]
+#[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const fn maxnumf32(_x: f32, _y: f32) -> f32 {
+    unimplemented!();
+}
+
+/// Returns the maximum of two `f64` values.
+///
+/// Note that, unlike most intrinsics, this is safe to call;
+/// it does not require an `unsafe` block.
+/// Therefore, implementations must not require the user to uphold
+/// any safety invariants.
+///
+/// The stabilized version of this intrinsic is
+/// [`f64::max`]
+#[rustc_nounwind]
+#[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const fn maxnumf64(_x: f64, _y: f64) -> f64 {
+    unimplemented!();
+}
+
+/// Returns the maximum of two `f128` values.
+///
+/// Note that, unlike most intrinsics, this is safe to call;
+/// it does not require an `unsafe` block.
+/// Therefore, implementations must not require the user to uphold
+/// any safety invariants.
+///
+/// The stabilized version of this intrinsic is
+/// [`f128::max`]
+#[rustc_nounwind]
+// #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+#[rustc_const_unstable(feature = "f128", issue = "116909")]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const fn maxnumf128(_x: f128, _y: f128) -> f128 {
+    unimplemented!();
+}
+
+/// Returns the absolute value of an `f16`.
+///
+/// The stabilized version of this intrinsic is
+/// [`f16::abs`](../../std/primitive.f16.html#method.abs)
+#[rustc_nounwind]
+// #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+#[rustc_const_unstable(feature = "f16", issue = "116909")]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const unsafe fn fabsf16(_x: f16) -> f16 {
+    unimplemented!();
+}
+
+/// Returns the absolute value of an `f32`.
+///
+/// The stabilized version of this intrinsic is
+/// [`f32::abs`](../../std/primitive.f32.html#method.abs)
+#[rustc_nounwind]
+#[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const unsafe fn fabsf32(_x: f32) -> f32 {
+    unimplemented!();
+}
+
+/// Returns the absolute value of an `f64`.
+///
+/// The stabilized version of this intrinsic is
+/// [`f64::abs`](../../std/primitive.f64.html#method.abs)
+#[rustc_nounwind]
+#[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const unsafe fn fabsf64(_x: f64) -> f64 {
+    unimplemented!();
+}
+
+/// Returns the absolute value of an `f128`.
+///
+/// The stabilized version of this intrinsic is
+/// [`f128::abs`](../../std/primitive.f128.html#method.abs)
+#[rustc_nounwind]
+// #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+#[rustc_const_unstable(feature = "f128", issue = "116909")]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const unsafe fn fabsf128(_x: f128) -> f128 {
+    unimplemented!();
+}
+
+/// Copies the sign from `y` to `x` for `f16` values.
+///
+/// The stabilized version of this intrinsic is
+/// [`f16::copysign`](../../std/primitive.f16.html#method.copysign)
+#[rustc_nounwind]
+// #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+#[rustc_const_unstable(feature = "f16", issue = "116909")]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const unsafe fn copysignf16(_x: f16, _y: f16) -> f16 {
+    unimplemented!();
+}
+
+/// Copies the sign from `y` to `x` for `f32` values.
+///
+/// The stabilized version of this intrinsic is
+/// [`f32::copysign`](../../std/primitive.f32.html#method.copysign)
+#[rustc_nounwind]
+#[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const unsafe fn copysignf32(_x: f32, _y: f32) -> f32 {
+    unimplemented!();
+}
+/// Copies the sign from `y` to `x` for `f64` values.
+///
+/// The stabilized version of this intrinsic is
+/// [`f64::copysign`](../../std/primitive.f64.html#method.copysign)
+#[rustc_nounwind]
+#[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const unsafe fn copysignf64(_x: f64, _y: f64) -> f64 {
+    unimplemented!();
+}
+
+/// Copies the sign from `y` to `x` for `f128` values.
+///
+/// The stabilized version of this intrinsic is
+/// [`f128::copysign`](../../std/primitive.f128.html#method.copysign)
+#[rustc_nounwind]
+// #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+#[rustc_const_unstable(feature = "f128", issue = "116909")]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const unsafe fn copysignf128(_x: f128, _y: f128) -> f128 {
+    unimplemented!();
+}
+
 /// Inform Miri that a given pointer definitely has a certain alignment.
 #[cfg(miri)]
 pub(crate) const fn miri_promise_symbolic_alignment(ptr: *const (), align: usize) {
diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs
index 7963459bfb5..302720eddef 100644
--- a/library/core/src/iter/traits/iterator.rs
+++ b/library/core/src/iter/traits/iterator.rs
@@ -9,7 +9,7 @@ use crate::cmp::{self, Ordering};
 use crate::num::NonZero;
 use crate::ops::{ChangeOutputType, ControlFlow, FromResidual, Residual, Try};
 
-fn _assert_is_object_safe(_: &dyn Iterator<Item = ()>) {}
+fn _assert_is_dyn_compatible(_: &dyn Iterator<Item = ()>) {}
 
 /// A trait for dealing with iterators.
 ///
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index e323e88f261..6ed9ccaa694 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -114,38 +114,28 @@
 #![feature(const_align_offset)]
 #![feature(const_alloc_layout)]
 #![feature(const_arguments_as_str)]
-#![feature(const_array_from_ref)]
 #![feature(const_array_into_iter_constructors)]
 #![feature(const_bigint_helper_methods)]
 #![feature(const_black_box)]
 #![feature(const_char_encode_utf16)]
-#![feature(const_char_encode_utf8)]
 #![feature(const_eval_select)]
 #![feature(const_exact_div)]
+#![feature(const_float_methods)]
 #![feature(const_fmt_arguments_new)]
 #![feature(const_hash)]
 #![feature(const_heap)]
 #![feature(const_index_range_slice_index)]
-#![feature(const_intrinsic_forget)]
-#![feature(const_ipv4)]
-#![feature(const_ipv6)]
 #![feature(const_likely)]
-#![feature(const_make_ascii)]
-#![feature(const_maybe_uninit_assume_init)]
 #![feature(const_nonnull_new)]
 #![feature(const_num_midpoint)]
-#![feature(const_option)]
 #![feature(const_option_ext)]
 #![feature(const_pin)]
 #![feature(const_pointer_is_aligned)]
 #![feature(const_ptr_is_null)]
 #![feature(const_ptr_sub_ptr)]
-#![feature(const_ptr_write)]
 #![feature(const_raw_ptr_comparison)]
-#![feature(const_replace)]
 #![feature(const_size_of_val)]
 #![feature(const_size_of_val_raw)]
-#![feature(const_slice_from_ref)]
 #![feature(const_strict_overflow_ops)]
 #![feature(const_swap)]
 #![feature(const_try)]
@@ -156,7 +146,6 @@
 #![feature(const_unicode_case_lookup)]
 #![feature(coverage_attribute)]
 #![feature(do_not_recommend)]
-#![feature(duration_consts_float)]
 #![feature(internal_impls_macro)]
 #![feature(ip)]
 #![feature(is_ascii_octdigit)]
@@ -164,6 +153,7 @@
 #![feature(isqrt)]
 #![feature(lazy_get)]
 #![feature(link_cfg)]
+#![feature(non_null_from_ref)]
 #![feature(offset_of_enum)]
 #![feature(panic_internals)]
 #![feature(ptr_alignment_type)]
@@ -184,8 +174,6 @@
 //
 // Language features:
 // tidy-alphabetical-start
-#![cfg_attr(bootstrap, feature(const_mut_refs))]
-#![cfg_attr(bootstrap, feature(const_refs_to_cell))]
 #![feature(abi_unadjusted)]
 #![feature(adt_const_params)]
 #![feature(allow_internal_unsafe)]
@@ -280,6 +268,15 @@ pub mod assert_matches {
     pub use crate::macros::{assert_matches, debug_assert_matches};
 }
 
+// We don't export this through #[macro_export] for now, to avoid breakage.
+#[cfg(not(bootstrap))]
+#[unstable(feature = "autodiff", issue = "124509")]
+/// Unstable module containing the unstable `autodiff` macro.
+pub mod autodiff {
+    #[unstable(feature = "autodiff", issue = "124509")]
+    pub use crate::macros::builtin::autodiff;
+}
+
 #[unstable(feature = "cfg_match", issue = "115585")]
 pub use crate::macros::cfg_match;
 
diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs
index aa0646846e4..6a4f2af10ef 100644
--- a/library/core/src/macros/mod.rs
+++ b/library/core/src/macros/mod.rs
@@ -1107,17 +1107,19 @@ pub(crate) mod builtin {
     ///
     /// If the named environment variable is present at compile time, this will
     /// expand into an expression of type `Option<&'static str>` whose value is
-    /// `Some` of the value of the environment variable. If the environment
-    /// variable is not present, then this will expand to `None`. See
-    /// [`Option<T>`][Option] for more information on this type.  Use
-    /// [`std::env::var`] instead if you want to read the value at runtime.
+    /// `Some` of the value of the environment variable (a compilation error
+    /// will be emitted if the environment variable is not a valid Unicode
+    /// string). If the environment variable is not present, then this will
+    /// expand to `None`. See [`Option<T>`][Option] for more information on this
+    /// type.  Use [`std::env::var`] instead if you want to read the value at
+    /// runtime.
     ///
     /// [`std::env::var`]: ../std/env/fn.var.html
     ///
-    /// A compile time error is never emitted when using this macro regardless
-    /// of whether the environment variable is present or not.
-    /// To emit a compile error if the environment variable is not present,
-    /// use the [`env!`] macro instead.
+    /// A compile time error is only emitted when using this macro if the
+    /// environment variable exists and is not a valid Unicode string. To also
+    /// emit a compile error if the environment variable is not present, use the
+    /// [`env!`] macro instead.
     ///
     /// # Examples
     ///
@@ -1539,6 +1541,24 @@ pub(crate) mod builtin {
         ($file:expr $(,)?) => {{ /* compiler built-in */ }};
     }
 
+    /// Automatic Differentiation macro which allows generating a new function to compute
+    /// the derivative of a given function. It may only be applied to a function.
+    /// The expected usage syntax is
+    /// `#[autodiff(NAME, MODE, INPUT_ACTIVITIES, OUTPUT_ACTIVITY)]`
+    /// where:
+    /// NAME is a string that represents a valid function name.
+    /// MODE is any of Forward, Reverse, ForwardFirst, ReverseFirst.
+    /// INPUT_ACTIVITIES consists of one valid activity for each input parameter.
+    /// OUTPUT_ACTIVITY must not be set if we implicitely return nothing (or explicitely return
+    /// `-> ()`. Otherwise it must be set to one of the allowed activities.
+    #[unstable(feature = "autodiff", issue = "124509")]
+    #[allow_internal_unstable(rustc_attrs)]
+    #[rustc_builtin_macro]
+    #[cfg(not(bootstrap))]
+    pub macro autodiff($item:item) {
+        /* compiler built-in */
+    }
+
     /// Asserts that a boolean expression is `true` at runtime.
     ///
     /// This will invoke the [`panic!`] macro if the provided expression cannot be
diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs
index fd41b80cdbd..aed6be4c627 100644
--- a/library/core/src/marker.rs
+++ b/library/core/src/marker.rs
@@ -158,7 +158,7 @@ pub trait Sized {
 /// - Arrays `[T; N]` implement `Unsize<[T]>`.
 /// - A type implements `Unsize<dyn Trait + 'a>` if all of these conditions are met:
 ///   - The type implements `Trait`.
-///   - `Trait` is object safe.
+///   - `Trait` is dyn-compatible[^1].
 ///   - The type is sized.
 ///   - The type outlives `'a`.
 /// - Structs `Foo<..., T1, ..., Tn, ...>` implement `Unsize<Foo<..., U1, ..., Un, ...>>`
@@ -178,6 +178,7 @@ pub trait Sized {
 /// [`Rc`]: ../../std/rc/struct.Rc.html
 /// [RFC982]: https://github.com/rust-lang/rfcs/blob/master/text/0982-dst-coercion.md
 /// [nomicon-coerce]: ../../nomicon/coercions.html
+/// [^1]: Formerly known as *object safe*.
 #[unstable(feature = "unsize", issue = "18598")]
 #[lang = "unsize"]
 #[rustc_deny_explicit_impl(implement_via_object = false)]
diff --git a/library/core/src/mem/maybe_uninit.rs b/library/core/src/mem/maybe_uninit.rs
index c67796ad3db..ea73cfc3781 100644
--- a/library/core/src/mem/maybe_uninit.rs
+++ b/library/core/src/mem/maybe_uninit.rs
@@ -569,11 +569,7 @@ impl<T> MaybeUninit<T> {
     /// (Notice that the rules around references to uninitialized data are not finalized yet, but
     /// until they are, it is advisable to avoid them.)
     #[stable(feature = "maybe_uninit", since = "1.36.0")]
-    #[rustc_const_stable(
-        feature = "const_maybe_uninit_as_mut_ptr",
-        since = "CURRENT_RUSTC_VERSION"
-    )]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
+    #[rustc_const_stable(feature = "const_maybe_uninit_as_mut_ptr", since = "1.83.0")]
     #[inline(always)]
     pub const fn as_mut_ptr(&mut self) -> *mut T {
         // `MaybeUninit` and `ManuallyDrop` are both `repr(transparent)` so we can cast the pointer.
@@ -913,7 +909,10 @@ impl<T> MaybeUninit<T> {
     /// };
     /// ```
     #[stable(feature = "maybe_uninit_ref", since = "1.55.0")]
-    #[rustc_const_unstable(feature = "const_maybe_uninit_assume_init", issue = "none")]
+    #[rustc_const_stable(
+        feature = "const_maybe_uninit_assume_init",
+        since = "CURRENT_RUSTC_VERSION"
+    )]
     #[inline(always)]
     pub const unsafe fn assume_init_mut(&mut self) -> &mut T {
         // SAFETY: the caller must guarantee that `self` is initialized.
@@ -999,7 +998,7 @@ impl<T> MaybeUninit<T> {
     ///
     /// [`assume_init_mut`]: MaybeUninit::assume_init_mut
     #[unstable(feature = "maybe_uninit_slice", issue = "63569")]
-    #[rustc_const_unstable(feature = "const_maybe_uninit_assume_init", issue = "none")]
+    #[rustc_const_unstable(feature = "maybe_uninit_slice", issue = "63569")]
     #[inline(always)]
     pub const unsafe fn slice_assume_init_mut(slice: &mut [Self]) -> &mut [T] {
         // SAFETY: similar to safety notes for `slice_get_ref`, but we have a
diff --git a/library/core/src/mem/mod.rs b/library/core/src/mem/mod.rs
index 414262fcf5a..74b198c4fdd 100644
--- a/library/core/src/mem/mod.rs
+++ b/library/core/src/mem/mod.rs
@@ -857,7 +857,7 @@ pub fn take<T: Default>(dest: &mut T) -> T {
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[must_use = "if you don't need the old value, you can just assign the new value directly"]
-#[rustc_const_unstable(feature = "const_replace", issue = "83164")]
+#[rustc_const_stable(feature = "const_replace", since = "1.83.0")]
 #[cfg_attr(not(test), rustc_diagnostic_item = "mem_replace")]
 pub const fn replace<T>(dest: &mut T, src: T) -> T {
     // It may be tempting to use `swap` to avoid `unsafe` here. Don't!
diff --git a/library/core/src/net/ip_addr.rs b/library/core/src/net/ip_addr.rs
index 919f681f911..d3360c18207 100644
--- a/library/core/src/net/ip_addr.rs
+++ b/library/core/src/net/ip_addr.rs
@@ -295,7 +295,6 @@ impl IpAddr {
     /// assert_eq!(IpAddr::V4(Ipv4Addr::new(80, 9, 12, 3)).is_global(), true);
     /// assert_eq!(IpAddr::V6(Ipv6Addr::new(0, 0, 0x1c9, 0, 0, 0xafc8, 0, 0x1)).is_global(), true);
     /// ```
-    #[rustc_const_unstable(feature = "const_ip", issue = "76205")]
     #[unstable(feature = "ip", issue = "27709")]
     #[must_use]
     #[inline]
@@ -348,7 +347,6 @@ impl IpAddr {
     ///     true
     /// );
     /// ```
-    #[rustc_const_unstable(feature = "const_ip", issue = "76205")]
     #[unstable(feature = "ip", issue = "27709")]
     #[must_use]
     #[inline]
@@ -600,6 +598,24 @@ impl Ipv4Addr {
         self.octets
     }
 
+    /// Creates an `Ipv4Addr` from a four element byte array.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(ip_from)]
+    /// use std::net::Ipv4Addr;
+    ///
+    /// let addr = Ipv4Addr::from_octets([13u8, 12u8, 11u8, 10u8]);
+    /// assert_eq!(Ipv4Addr::new(13, 12, 11, 10), addr);
+    /// ```
+    #[unstable(feature = "ip_from", issue = "131360")]
+    #[must_use]
+    #[inline]
+    pub const fn from_octets(octets: [u8; 4]) -> Ipv4Addr {
+        Ipv4Addr { octets }
+    }
+
     /// Returns [`true`] for the special 'unspecified' address (`0.0.0.0`).
     ///
     /// This property is defined in _UNIX Network Programming, Second Edition_,
@@ -776,7 +792,6 @@ impl Ipv4Addr {
     ///
     /// // For a complete overview see the IANA IPv4 Special-Purpose Address Registry.
     /// ```
-    #[rustc_const_unstable(feature = "const_ipv4", issue = "76205")]
     #[unstable(feature = "ip", issue = "27709")]
     #[must_use]
     #[inline]
@@ -813,7 +828,6 @@ impl Ipv4Addr {
     /// assert_eq!(Ipv4Addr::new(100, 127, 255, 255).is_shared(), true);
     /// assert_eq!(Ipv4Addr::new(100, 128, 0, 0).is_shared(), false);
     /// ```
-    #[rustc_const_unstable(feature = "const_ipv4", issue = "76205")]
     #[unstable(feature = "ip", issue = "27709")]
     #[must_use]
     #[inline]
@@ -841,7 +855,6 @@ impl Ipv4Addr {
     /// assert_eq!(Ipv4Addr::new(198, 19, 255, 255).is_benchmarking(), true);
     /// assert_eq!(Ipv4Addr::new(198, 20, 0, 0).is_benchmarking(), false);
     /// ```
-    #[rustc_const_unstable(feature = "const_ipv4", issue = "76205")]
     #[unstable(feature = "ip", issue = "27709")]
     #[must_use]
     #[inline]
@@ -878,7 +891,6 @@ impl Ipv4Addr {
     /// // The broadcast address is not considered as reserved for future use by this implementation
     /// assert_eq!(Ipv4Addr::new(255, 255, 255, 255).is_reserved(), false);
     /// ```
-    #[rustc_const_unstable(feature = "const_ipv4", issue = "76205")]
     #[unstable(feature = "ip", issue = "27709")]
     #[must_use]
     #[inline]
@@ -1400,6 +1412,34 @@ impl Ipv6Addr {
         ]
     }
 
+    /// Creates an `Ipv6Addr` from an eight element 16-bit array.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(ip_from)]
+    /// use std::net::Ipv6Addr;
+    ///
+    /// let addr = Ipv6Addr::from_segments([
+    ///     0x20du16, 0x20cu16, 0x20bu16, 0x20au16,
+    ///     0x209u16, 0x208u16, 0x207u16, 0x206u16,
+    /// ]);
+    /// assert_eq!(
+    ///     Ipv6Addr::new(
+    ///         0x20d, 0x20c, 0x20b, 0x20a,
+    ///         0x209, 0x208, 0x207, 0x206,
+    ///     ),
+    ///     addr
+    /// );
+    /// ```
+    #[unstable(feature = "ip_from", issue = "131360")]
+    #[must_use]
+    #[inline]
+    pub const fn from_segments(segments: [u16; 8]) -> Ipv6Addr {
+        let [a, b, c, d, e, f, g, h] = segments;
+        Ipv6Addr::new(a, b, c, d, e, f, g, h)
+    }
+
     /// Returns [`true`] for the special 'unspecified' address (`::`).
     ///
     /// This property is defined in [IETF RFC 4291].
@@ -1510,7 +1550,6 @@ impl Ipv6Addr {
     ///
     /// // For a complete overview see the IANA IPv6 Special-Purpose Address Registry.
     /// ```
-    #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
     #[unstable(feature = "ip", issue = "27709")]
     #[must_use]
     #[inline]
@@ -1562,7 +1601,6 @@ impl Ipv6Addr {
     /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_unique_local(), false);
     /// assert_eq!(Ipv6Addr::new(0xfc02, 0, 0, 0, 0, 0, 0, 0).is_unique_local(), true);
     /// ```
-    #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
     #[unstable(feature = "ip", issue = "27709")]
     #[must_use]
     #[inline]
@@ -1591,7 +1629,6 @@ impl Ipv6Addr {
     /// assert_eq!(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 0).is_unicast(), true);
     /// assert_eq!(Ipv6Addr::new(0xff00, 0, 0, 0, 0, 0, 0, 0).is_unicast(), false);
     /// ```
-    #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
     #[unstable(feature = "ip", issue = "27709")]
     #[must_use]
     #[inline]
@@ -1643,7 +1680,6 @@ impl Ipv6Addr {
     /// assert_eq!(Ipv6Addr::new(0xfe80, 0, 0, 1, 0, 0, 0, 0).is_unicast_link_local(), true);
     /// assert_eq!(Ipv6Addr::new(0xfe81, 0, 0, 0, 0, 0, 0, 0).is_unicast_link_local(), true);
     /// ```
-    #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
     #[unstable(feature = "ip", issue = "27709")]
     #[must_use]
     #[inline]
@@ -1668,7 +1704,6 @@ impl Ipv6Addr {
     /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_documentation(), false);
     /// assert_eq!(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 0).is_documentation(), true);
     /// ```
-    #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
     #[unstable(feature = "ip", issue = "27709")]
     #[must_use]
     #[inline]
@@ -1729,7 +1764,6 @@ impl Ipv6Addr {
     /// assert_eq!(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 0).is_unicast_global(), false);
     /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).is_unicast_global(), true);
     /// ```
-    #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
     #[unstable(feature = "ip", issue = "27709")]
     #[must_use]
     #[inline]
@@ -1758,7 +1792,6 @@ impl Ipv6Addr {
     /// );
     /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).multicast_scope(), None);
     /// ```
-    #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
     #[unstable(feature = "ip", issue = "27709")]
     #[must_use]
     #[inline]
@@ -1818,7 +1851,6 @@ impl Ipv6Addr {
     ///
     /// assert_eq!(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 0).is_ipv4_mapped(), false);
     /// ```
-    #[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
     #[unstable(feature = "ip", issue = "27709")]
     #[must_use]
     #[inline]
@@ -1932,7 +1964,7 @@ impl Ipv6Addr {
     /// use std::net::Ipv6Addr;
     ///
     /// assert_eq!(Ipv6Addr::new(0xff00, 0, 0, 0, 0, 0, 0, 0).octets(),
-    ///            [255, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]);
+    ///            [0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]);
     /// ```
     #[rustc_const_stable(feature = "const_ip_32", since = "1.32.0")]
     #[stable(feature = "ipv6_to_octets", since = "1.12.0")]
@@ -1941,6 +1973,33 @@ impl Ipv6Addr {
     pub const fn octets(&self) -> [u8; 16] {
         self.octets
     }
+
+    /// Creates an `Ipv6Addr` from a sixteen element byte array.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(ip_from)]
+    /// use std::net::Ipv6Addr;
+    ///
+    /// let addr = Ipv6Addr::from_octets([
+    ///     0x19u8, 0x18u8, 0x17u8, 0x16u8, 0x15u8, 0x14u8, 0x13u8, 0x12u8,
+    ///     0x11u8, 0x10u8, 0x0fu8, 0x0eu8, 0x0du8, 0x0cu8, 0x0bu8, 0x0au8,
+    /// ]);
+    /// assert_eq!(
+    ///     Ipv6Addr::new(
+    ///         0x1918, 0x1716, 0x1514, 0x1312,
+    ///         0x1110, 0x0f0e, 0x0d0c, 0x0b0a,
+    ///     ),
+    ///     addr
+    /// );
+    /// ```
+    #[unstable(feature = "ip_from", issue = "131360")]
+    #[must_use]
+    #[inline]
+    pub const fn from_octets(octets: [u8; 16]) -> Ipv6Addr {
+        Ipv6Addr { octets }
+    }
 }
 
 /// Writes an Ipv6Addr, conforming to the canonical style described by
@@ -2113,15 +2172,13 @@ impl From<[u8; 16]> for Ipv6Addr {
     /// use std::net::Ipv6Addr;
     ///
     /// let addr = Ipv6Addr::from([
-    ///     25u8, 24u8, 23u8, 22u8, 21u8, 20u8, 19u8, 18u8,
-    ///     17u8, 16u8, 15u8, 14u8, 13u8, 12u8, 11u8, 10u8,
+    ///     0x19u8, 0x18u8, 0x17u8, 0x16u8, 0x15u8, 0x14u8, 0x13u8, 0x12u8,
+    ///     0x11u8, 0x10u8, 0x0fu8, 0x0eu8, 0x0du8, 0x0cu8, 0x0bu8, 0x0au8,
     /// ]);
     /// assert_eq!(
     ///     Ipv6Addr::new(
-    ///         0x1918, 0x1716,
-    ///         0x1514, 0x1312,
-    ///         0x1110, 0x0f0e,
-    ///         0x0d0c, 0x0b0a
+    ///         0x1918, 0x1716, 0x1514, 0x1312,
+    ///         0x1110, 0x0f0e, 0x0d0c, 0x0b0a,
     ///     ),
     ///     addr
     /// );
@@ -2142,15 +2199,13 @@ impl From<[u16; 8]> for Ipv6Addr {
     /// use std::net::Ipv6Addr;
     ///
     /// let addr = Ipv6Addr::from([
-    ///     525u16, 524u16, 523u16, 522u16,
-    ///     521u16, 520u16, 519u16, 518u16,
+    ///     0x20du16, 0x20cu16, 0x20bu16, 0x20au16,
+    ///     0x209u16, 0x208u16, 0x207u16, 0x206u16,
     /// ]);
     /// assert_eq!(
     ///     Ipv6Addr::new(
-    ///         0x20d, 0x20c,
-    ///         0x20b, 0x20a,
-    ///         0x209, 0x208,
-    ///         0x207, 0x206
+    ///         0x20d, 0x20c, 0x20b, 0x20a,
+    ///         0x209, 0x208, 0x207, 0x206,
     ///     ),
     ///     addr
     /// );
@@ -2172,15 +2227,13 @@ impl From<[u8; 16]> for IpAddr {
     /// use std::net::{IpAddr, Ipv6Addr};
     ///
     /// let addr = IpAddr::from([
-    ///     25u8, 24u8, 23u8, 22u8, 21u8, 20u8, 19u8, 18u8,
-    ///     17u8, 16u8, 15u8, 14u8, 13u8, 12u8, 11u8, 10u8,
+    ///     0x19u8, 0x18u8, 0x17u8, 0x16u8, 0x15u8, 0x14u8, 0x13u8, 0x12u8,
+    ///     0x11u8, 0x10u8, 0x0fu8, 0x0eu8, 0x0du8, 0x0cu8, 0x0bu8, 0x0au8,
     /// ]);
     /// assert_eq!(
     ///     IpAddr::V6(Ipv6Addr::new(
-    ///         0x1918, 0x1716,
-    ///         0x1514, 0x1312,
-    ///         0x1110, 0x0f0e,
-    ///         0x0d0c, 0x0b0a
+    ///         0x1918, 0x1716, 0x1514, 0x1312,
+    ///         0x1110, 0x0f0e, 0x0d0c, 0x0b0a,
     ///     )),
     ///     addr
     /// );
@@ -2201,15 +2254,13 @@ impl From<[u16; 8]> for IpAddr {
     /// use std::net::{IpAddr, Ipv6Addr};
     ///
     /// let addr = IpAddr::from([
-    ///     525u16, 524u16, 523u16, 522u16,
-    ///     521u16, 520u16, 519u16, 518u16,
+    ///     0x20du16, 0x20cu16, 0x20bu16, 0x20au16,
+    ///     0x209u16, 0x208u16, 0x207u16, 0x206u16,
     /// ]);
     /// assert_eq!(
     ///     IpAddr::V6(Ipv6Addr::new(
-    ///         0x20d, 0x20c,
-    ///         0x20b, 0x20a,
-    ///         0x209, 0x208,
-    ///         0x207, 0x206
+    ///         0x20d, 0x20c, 0x20b, 0x20a,
+    ///         0x209, 0x208, 0x207, 0x206,
     ///     )),
     ///     addr
     /// );
diff --git a/library/core/src/num/f128.rs b/library/core/src/num/f128.rs
index 764df4fe4b0..5ab2ab50d7c 100644
--- a/library/core/src/num/f128.rs
+++ b/library/core/src/num/f128.rs
@@ -471,7 +471,7 @@ impl f128 {
     #[inline]
     #[must_use]
     #[unstable(feature = "f128", issue = "116909")]
-    pub fn is_sign_positive(self) -> bool {
+    pub const fn is_sign_positive(self) -> bool {
         !self.is_sign_negative()
     }
 
@@ -497,7 +497,7 @@ impl f128 {
     #[inline]
     #[must_use]
     #[unstable(feature = "f128", issue = "116909")]
-    pub fn is_sign_negative(self) -> bool {
+    pub const fn is_sign_negative(self) -> bool {
         // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
         // applies to zeros and NaNs as well.
         // SAFETY: This is just transmuting to get the sign bit, it's fine.
@@ -538,7 +538,7 @@ impl f128 {
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
     // #[unstable(feature = "float_next_up_down", issue = "91399")]
-    pub fn next_up(self) -> Self {
+    pub const fn next_up(self) -> Self {
         // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
         // denormals to zero. This is in general unsound and unsupported, but here
         // we do our best to still produce the correct result on such targets.
@@ -592,7 +592,7 @@ impl f128 {
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
     // #[unstable(feature = "float_next_up_down", issue = "91399")]
-    pub fn next_down(self) -> Self {
+    pub const fn next_down(self) -> Self {
         // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
         // denormals to zero. This is in general unsound and unsupported, but here
         // we do our best to still produce the correct result on such targets.
@@ -627,8 +627,9 @@ impl f128 {
     /// ```
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
-    pub fn recip(self) -> Self {
+    pub const fn recip(self) -> Self {
         1.0 / self
     }
 
@@ -647,8 +648,9 @@ impl f128 {
     /// ```
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
-    pub fn to_degrees(self) -> Self {
+    pub const fn to_degrees(self) -> Self {
         // Use a literal for better precision.
         const PIS_IN_180: f128 = 57.2957795130823208767981548141051703324054724665643215491602_f128;
         self * PIS_IN_180
@@ -670,8 +672,9 @@ impl f128 {
     /// ```
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
-    pub fn to_radians(self) -> f128 {
+    pub const fn to_radians(self) -> f128 {
         // Use a literal for better precision.
         const RADS_PER_DEG: f128 =
             0.0174532925199432957692369076848861271344287188854172545609719_f128;
@@ -698,8 +701,9 @@ impl f128 {
     /// ```
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
-    pub fn max(self, other: f128) -> f128 {
+    pub const fn max(self, other: f128) -> f128 {
         intrinsics::maxnumf128(self, other)
     }
 
@@ -723,8 +727,9 @@ impl f128 {
     /// ```
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
-    pub fn min(self, other: f128) -> f128 {
+    pub const fn min(self, other: f128) -> f128 {
         intrinsics::minnumf128(self, other)
     }
 
@@ -757,7 +762,7 @@ impl f128 {
     #[unstable(feature = "f128", issue = "116909")]
     // #[unstable(feature = "float_minimum_maximum", issue = "91079")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
-    pub fn maximum(self, other: f128) -> f128 {
+    pub const fn maximum(self, other: f128) -> f128 {
         if self > other {
             self
         } else if other > self {
@@ -798,7 +803,7 @@ impl f128 {
     #[unstable(feature = "f128", issue = "116909")]
     // #[unstable(feature = "float_minimum_maximum", issue = "91079")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
-    pub fn minimum(self, other: f128) -> f128 {
+    pub const fn minimum(self, other: f128) -> f128 {
         if self < other {
             self
         } else if other < self {
@@ -1269,9 +1274,20 @@ impl f128 {
     /// ```
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "method returns a new number and does not mutate the original value"]
-    pub fn clamp(mut self, min: f128, max: f128) -> f128 {
-        assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}");
+    pub const fn clamp(mut self, min: f128, max: f128) -> f128 {
+        #[inline] // inline to avoid LLVM crash
+        const fn assert_at_const(min: f128, max: f128) {
+            // Note that we cannot format in constant expressions.
+            assert!(min <= max, "min > max, or either was NaN");
+        }
+        #[inline] // inline to avoid codegen regression
+        fn assert_at_rt(min: f128, max: f128) {
+            assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}");
+        }
+        // FIXME(const-hack): We would prefer to have streamlined panics when formatters become const-friendly.
+        intrinsics::const_eval_select((min, max), assert_at_const, assert_at_rt);
         if self < min {
             self = min;
         }
diff --git a/library/core/src/num/f16.rs b/library/core/src/num/f16.rs
index 897fc8c105d..60a88496696 100644
--- a/library/core/src/num/f16.rs
+++ b/library/core/src/num/f16.rs
@@ -459,7 +459,7 @@ impl f16 {
     #[inline]
     #[must_use]
     #[unstable(feature = "f16", issue = "116909")]
-    pub fn is_sign_positive(self) -> bool {
+    pub const fn is_sign_positive(self) -> bool {
         !self.is_sign_negative()
     }
 
@@ -488,7 +488,7 @@ impl f16 {
     #[inline]
     #[must_use]
     #[unstable(feature = "f16", issue = "116909")]
-    pub fn is_sign_negative(self) -> bool {
+    pub const fn is_sign_negative(self) -> bool {
         // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
         // applies to zeros and NaNs as well.
         // SAFETY: This is just transmuting to get the sign bit, it's fine.
@@ -529,7 +529,7 @@ impl f16 {
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
     // #[unstable(feature = "float_next_up_down", issue = "91399")]
-    pub fn next_up(self) -> Self {
+    pub const fn next_up(self) -> Self {
         // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
         // denormals to zero. This is in general unsound and unsupported, but here
         // we do our best to still produce the correct result on such targets.
@@ -583,7 +583,7 @@ impl f16 {
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
     // #[unstable(feature = "float_next_up_down", issue = "91399")]
-    pub fn next_down(self) -> Self {
+    pub const fn next_down(self) -> Self {
         // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
         // denormals to zero. This is in general unsound and unsupported, but here
         // we do our best to still produce the correct result on such targets.
@@ -618,8 +618,9 @@ impl f16 {
     /// ```
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
-    pub fn recip(self) -> Self {
+    pub const fn recip(self) -> Self {
         1.0 / self
     }
 
@@ -638,8 +639,9 @@ impl f16 {
     /// ```
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
-    pub fn to_degrees(self) -> Self {
+    pub const fn to_degrees(self) -> Self {
         // Use a literal for better precision.
         const PIS_IN_180: f16 = 57.2957795130823208767981548141051703_f16;
         self * PIS_IN_180
@@ -661,8 +663,9 @@ impl f16 {
     /// ```
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
-    pub fn to_radians(self) -> f16 {
+    pub const fn to_radians(self) -> f16 {
         // Use a literal for better precision.
         const RADS_PER_DEG: f16 = 0.017453292519943295769236907684886_f16;
         self * RADS_PER_DEG
@@ -687,8 +690,9 @@ impl f16 {
     /// ```
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
-    pub fn max(self, other: f16) -> f16 {
+    pub const fn max(self, other: f16) -> f16 {
         intrinsics::maxnumf16(self, other)
     }
 
@@ -711,8 +715,9 @@ impl f16 {
     /// ```
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
-    pub fn min(self, other: f16) -> f16 {
+    pub const fn min(self, other: f16) -> f16 {
         intrinsics::minnumf16(self, other)
     }
 
@@ -744,7 +749,7 @@ impl f16 {
     #[unstable(feature = "f16", issue = "116909")]
     // #[unstable(feature = "float_minimum_maximum", issue = "91079")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
-    pub fn maximum(self, other: f16) -> f16 {
+    pub const fn maximum(self, other: f16) -> f16 {
         if self > other {
             self
         } else if other > self {
@@ -784,7 +789,7 @@ impl f16 {
     #[unstable(feature = "f16", issue = "116909")]
     // #[unstable(feature = "float_minimum_maximum", issue = "91079")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
-    pub fn minimum(self, other: f16) -> f16 {
+    pub const fn minimum(self, other: f16) -> f16 {
         if self < other {
             self
         } else if other < self {
@@ -1244,9 +1249,20 @@ impl f16 {
     /// ```
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "method returns a new number and does not mutate the original value"]
-    pub fn clamp(mut self, min: f16, max: f16) -> f16 {
-        assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}");
+    pub const fn clamp(mut self, min: f16, max: f16) -> f16 {
+        #[inline] // inline to avoid LLVM crash
+        const fn assert_at_const(min: f16, max: f16) {
+            // Note that we cannot format in constant expressions.
+            assert!(min <= max, "min > max, or either was NaN");
+        }
+        #[inline] // inline to avoid codegen regression
+        fn assert_at_rt(min: f16, max: f16) {
+            assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}");
+        }
+        // FIXME(const-hack): We would prefer to have streamlined panics when formatters become const-friendly.
+        intrinsics::const_eval_select((min, max), assert_at_const, assert_at_rt);
         if self < min {
             self = min;
         }
diff --git a/library/core/src/num/f32.rs b/library/core/src/num/f32.rs
index a9a2595c25c..a01761ee5d4 100644
--- a/library/core/src/num/f32.rs
+++ b/library/core/src/num/f32.rs
@@ -517,7 +517,7 @@ impl f32 {
     /// ```
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_float_classify", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
     #[inline]
     #[allow(clippy::eq_op)] // > if you intended to check if the operand is NaN, use `.is_nan()` instead :)
     pub const fn is_nan(self) -> bool {
@@ -550,7 +550,7 @@ impl f32 {
     /// ```
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_float_classify", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
     #[inline]
     pub const fn is_infinite(self) -> bool {
         // Getting clever with transmutation can result in incorrect answers on some FPUs
@@ -575,7 +575,7 @@ impl f32 {
     /// ```
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_float_classify", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
     #[inline]
     pub const fn is_finite(self) -> bool {
         // There's no need to handle NaN separately: if self is NaN,
@@ -603,7 +603,7 @@ impl f32 {
     /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
     #[must_use]
     #[stable(feature = "is_subnormal", since = "1.53.0")]
-    #[rustc_const_stable(feature = "const_float_classify", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
     #[inline]
     pub const fn is_subnormal(self) -> bool {
         matches!(self.classify(), FpCategory::Subnormal)
@@ -630,7 +630,7 @@ impl f32 {
     /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_float_classify", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
     #[inline]
     pub const fn is_normal(self) -> bool {
         matches!(self.classify(), FpCategory::Normal)
@@ -650,7 +650,7 @@ impl f32 {
     /// assert_eq!(inf.classify(), FpCategory::Infinite);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_float_classify", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
     pub const fn classify(self) -> FpCategory {
         // We used to have complicated logic here that avoids the simple bit-based tests to work
         // around buggy codegen for x87 targets (see
@@ -686,7 +686,7 @@ impl f32 {
     /// ```
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_float_classify", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
     #[inline]
     pub const fn is_sign_positive(self) -> bool {
         !self.is_sign_negative()
@@ -711,7 +711,7 @@ impl f32 {
     /// ```
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_float_classify", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
     #[inline]
     pub const fn is_sign_negative(self) -> bool {
         // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
@@ -828,8 +828,9 @@ impl f32 {
     /// ```
     #[must_use = "this returns the result of the operation, without modifying the original"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn recip(self) -> f32 {
+    pub const fn recip(self) -> f32 {
         1.0 / self
     }
 
@@ -845,8 +846,9 @@ impl f32 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn to_degrees(self) -> f32 {
+    pub const fn to_degrees(self) -> f32 {
         // Use a constant for better precision.
         const PIS_IN_180: f32 = 57.2957795130823208767981548141051703_f32;
         self * PIS_IN_180
@@ -864,8 +866,9 @@ impl f32 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn to_radians(self) -> f32 {
+    pub const fn to_radians(self) -> f32 {
         const RADS_PER_DEG: f32 = consts::PI / 180.0;
         self * RADS_PER_DEG
     }
@@ -885,8 +888,9 @@ impl f32 {
     /// ```
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn max(self, other: f32) -> f32 {
+    pub const fn max(self, other: f32) -> f32 {
         intrinsics::maxnumf32(self, other)
     }
 
@@ -905,8 +909,9 @@ impl f32 {
     /// ```
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn min(self, other: f32) -> f32 {
+    pub const fn min(self, other: f32) -> f32 {
         intrinsics::minnumf32(self, other)
     }
 
@@ -933,7 +938,7 @@ impl f32 {
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     #[unstable(feature = "float_minimum_maximum", issue = "91079")]
     #[inline]
-    pub fn maximum(self, other: f32) -> f32 {
+    pub const fn maximum(self, other: f32) -> f32 {
         if self > other {
             self
         } else if other > self {
@@ -968,7 +973,7 @@ impl f32 {
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     #[unstable(feature = "float_minimum_maximum", issue = "91079")]
     #[inline]
-    pub fn minimum(self, other: f32) -> f32 {
+    pub const fn minimum(self, other: f32) -> f32 {
         if self < other {
             self
         } else if other < self {
@@ -1088,7 +1093,7 @@ impl f32 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "float_bits_conv", since = "1.20.0")]
-    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
     #[inline]
     pub const fn to_bits(self) -> u32 {
         // SAFETY: `u32` is a plain old datatype so we can always transmute to it.
@@ -1132,7 +1137,7 @@ impl f32 {
     /// assert_eq!(v, 12.5);
     /// ```
     #[stable(feature = "float_bits_conv", since = "1.20.0")]
-    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
     #[must_use]
     #[inline]
     pub const fn from_bits(v: u32) -> Self {
@@ -1156,7 +1161,7 @@ impl f32 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
     #[inline]
     pub const fn to_be_bytes(self) -> [u8; 4] {
         self.to_bits().to_be_bytes()
@@ -1177,7 +1182,7 @@ impl f32 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
     #[inline]
     pub const fn to_le_bytes(self) -> [u8; 4] {
         self.to_bits().to_le_bytes()
@@ -1211,7 +1216,7 @@ impl f32 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
     #[inline]
     pub const fn to_ne_bytes(self) -> [u8; 4] {
         self.to_bits().to_ne_bytes()
@@ -1229,7 +1234,7 @@ impl f32 {
     /// assert_eq!(value, 12.5);
     /// ```
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
     #[must_use]
     #[inline]
     pub const fn from_be_bytes(bytes: [u8; 4]) -> Self {
@@ -1248,7 +1253,7 @@ impl f32 {
     /// assert_eq!(value, 12.5);
     /// ```
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
     #[must_use]
     #[inline]
     pub const fn from_le_bytes(bytes: [u8; 4]) -> Self {
@@ -1278,7 +1283,7 @@ impl f32 {
     /// assert_eq!(value, 12.5);
     /// ```
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
     #[must_use]
     #[inline]
     pub const fn from_ne_bytes(bytes: [u8; 4]) -> Self {
@@ -1401,9 +1406,19 @@ impl f32 {
     /// ```
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[stable(feature = "clamp", since = "1.50.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn clamp(mut self, min: f32, max: f32) -> f32 {
-        assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}");
+    pub const fn clamp(mut self, min: f32, max: f32) -> f32 {
+        const fn assert_at_const(min: f32, max: f32) {
+            // Note that we cannot format in constant expressions.
+            assert!(min <= max, "min > max, or either was NaN");
+        }
+        #[inline] // inline to avoid codegen regression
+        fn assert_at_rt(min: f32, max: f32) {
+            assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}");
+        }
+        // FIXME(const-hack): We would prefer to have streamlined panics when formatters become const-friendly.
+        intrinsics::const_eval_select((min, max), assert_at_const, assert_at_rt);
         if self < min {
             self = min;
         }
diff --git a/library/core/src/num/f64.rs b/library/core/src/num/f64.rs
index aa7a54ca650..2995e41cd6e 100644
--- a/library/core/src/num/f64.rs
+++ b/library/core/src/num/f64.rs
@@ -516,7 +516,7 @@ impl f64 {
     /// ```
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_float_classify", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
     #[inline]
     #[allow(clippy::eq_op)] // > if you intended to check if the operand is NaN, use `.is_nan()` instead :)
     pub const fn is_nan(self) -> bool {
@@ -549,7 +549,7 @@ impl f64 {
     /// ```
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_float_classify", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
     #[inline]
     pub const fn is_infinite(self) -> bool {
         // Getting clever with transmutation can result in incorrect answers on some FPUs
@@ -574,7 +574,7 @@ impl f64 {
     /// ```
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_float_classify", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
     #[inline]
     pub const fn is_finite(self) -> bool {
         // There's no need to handle NaN separately: if self is NaN,
@@ -602,7 +602,7 @@ impl f64 {
     /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
     #[must_use]
     #[stable(feature = "is_subnormal", since = "1.53.0")]
-    #[rustc_const_stable(feature = "const_float_classify", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
     #[inline]
     pub const fn is_subnormal(self) -> bool {
         matches!(self.classify(), FpCategory::Subnormal)
@@ -629,7 +629,7 @@ impl f64 {
     /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_float_classify", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
     #[inline]
     pub const fn is_normal(self) -> bool {
         matches!(self.classify(), FpCategory::Normal)
@@ -649,7 +649,7 @@ impl f64 {
     /// assert_eq!(inf.classify(), FpCategory::Infinite);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_float_classify", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
     pub const fn classify(self) -> FpCategory {
         // We used to have complicated logic here that avoids the simple bit-based tests to work
         // around buggy codegen for x87 targets (see
@@ -685,7 +685,7 @@ impl f64 {
     /// ```
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_float_classify", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
     #[inline]
     pub const fn is_sign_positive(self) -> bool {
         !self.is_sign_negative()
@@ -719,7 +719,7 @@ impl f64 {
     /// ```
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_stable(feature = "const_float_classify", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
     #[inline]
     pub const fn is_sign_negative(self) -> bool {
         // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
@@ -845,8 +845,9 @@ impl f64 {
     /// ```
     #[must_use = "this returns the result of the operation, without modifying the original"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn recip(self) -> f64 {
+    pub const fn recip(self) -> f64 {
         1.0 / self
     }
 
@@ -862,8 +863,9 @@ impl f64 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn to_degrees(self) -> f64 {
+    pub const fn to_degrees(self) -> f64 {
         // The division here is correctly rounded with respect to the true
         // value of 180/π. (This differs from f32, where a constant must be
         // used to ensure a correctly rounded result.)
@@ -882,8 +884,9 @@ impl f64 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn to_radians(self) -> f64 {
+    pub const fn to_radians(self) -> f64 {
         const RADS_PER_DEG: f64 = consts::PI / 180.0;
         self * RADS_PER_DEG
     }
@@ -903,8 +906,9 @@ impl f64 {
     /// ```
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn max(self, other: f64) -> f64 {
+    pub const fn max(self, other: f64) -> f64 {
         intrinsics::maxnumf64(self, other)
     }
 
@@ -923,8 +927,9 @@ impl f64 {
     /// ```
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn min(self, other: f64) -> f64 {
+    pub const fn min(self, other: f64) -> f64 {
         intrinsics::minnumf64(self, other)
     }
 
@@ -951,7 +956,7 @@ impl f64 {
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     #[unstable(feature = "float_minimum_maximum", issue = "91079")]
     #[inline]
-    pub fn maximum(self, other: f64) -> f64 {
+    pub const fn maximum(self, other: f64) -> f64 {
         if self > other {
             self
         } else if other > self {
@@ -986,7 +991,7 @@ impl f64 {
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     #[unstable(feature = "float_minimum_maximum", issue = "91079")]
     #[inline]
-    pub fn minimum(self, other: f64) -> f64 {
+    pub const fn minimum(self, other: f64) -> f64 {
         if self < other {
             self
         } else if other < self {
@@ -1088,7 +1093,7 @@ impl f64 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "float_bits_conv", since = "1.20.0")]
-    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
     #[inline]
     pub const fn to_bits(self) -> u64 {
         // SAFETY: `u64` is a plain old datatype so we can always transmute to it.
@@ -1132,7 +1137,7 @@ impl f64 {
     /// assert_eq!(v, 12.5);
     /// ```
     #[stable(feature = "float_bits_conv", since = "1.20.0")]
-    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
     #[must_use]
     #[inline]
     pub const fn from_bits(v: u64) -> Self {
@@ -1156,7 +1161,7 @@ impl f64 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
     #[inline]
     pub const fn to_be_bytes(self) -> [u8; 8] {
         self.to_bits().to_be_bytes()
@@ -1177,7 +1182,7 @@ impl f64 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
     #[inline]
     pub const fn to_le_bytes(self) -> [u8; 8] {
         self.to_bits().to_le_bytes()
@@ -1211,7 +1216,7 @@ impl f64 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
     #[inline]
     pub const fn to_ne_bytes(self) -> [u8; 8] {
         self.to_bits().to_ne_bytes()
@@ -1229,7 +1234,7 @@ impl f64 {
     /// assert_eq!(value, 12.5);
     /// ```
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
     #[must_use]
     #[inline]
     pub const fn from_be_bytes(bytes: [u8; 8]) -> Self {
@@ -1248,7 +1253,7 @@ impl f64 {
     /// assert_eq!(value, 12.5);
     /// ```
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
     #[must_use]
     #[inline]
     pub const fn from_le_bytes(bytes: [u8; 8]) -> Self {
@@ -1278,7 +1283,7 @@ impl f64 {
     /// assert_eq!(value, 12.5);
     /// ```
     #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
-    #[rustc_const_stable(feature = "const_float_bits_conv", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
     #[must_use]
     #[inline]
     pub const fn from_ne_bytes(bytes: [u8; 8]) -> Self {
@@ -1401,9 +1406,19 @@ impl f64 {
     /// ```
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[stable(feature = "clamp", since = "1.50.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn clamp(mut self, min: f64, max: f64) -> f64 {
-        assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}");
+    pub const fn clamp(mut self, min: f64, max: f64) -> f64 {
+        const fn assert_at_const(min: f64, max: f64) {
+            // Note that we cannot format in constant expressions.
+            assert!(min <= max, "min > max, or either was NaN");
+        }
+        #[inline] // inline to avoid codegen regression
+        fn assert_at_rt(min: f64, max: f64) {
+            assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}");
+        }
+        // FIXME(const-hack): We would prefer to have streamlined panics when formatters become const-friendly.
+        intrinsics::const_eval_select((min, max), assert_at_const, assert_at_rt);
         if self < min {
             self = min;
         }
diff --git a/library/core/src/num/mod.rs b/library/core/src/num/mod.rs
index 31e35015d2d..5e2f45884dd 100644
--- a/library/core/src/num/mod.rs
+++ b/library/core/src/num/mod.rs
@@ -624,7 +624,7 @@ impl u8 {
     ///
     /// [`to_ascii_uppercase`]: Self::to_ascii_uppercase
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
-    #[rustc_const_unstable(feature = "const_make_ascii", issue = "130698")]
+    #[rustc_const_stable(feature = "const_make_ascii", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn make_ascii_uppercase(&mut self) {
         *self = self.to_ascii_uppercase();
@@ -650,7 +650,7 @@ impl u8 {
     ///
     /// [`to_ascii_lowercase`]: Self::to_ascii_lowercase
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
-    #[rustc_const_unstable(feature = "const_make_ascii", issue = "130698")]
+    #[rustc_const_stable(feature = "const_make_ascii", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn make_ascii_lowercase(&mut self) {
         *self = self.to_ascii_lowercase();
diff --git a/library/core/src/ops/control_flow.rs b/library/core/src/ops/control_flow.rs
index 7a8158b8231..55deabbee8f 100644
--- a/library/core/src/ops/control_flow.rs
+++ b/library/core/src/ops/control_flow.rs
@@ -177,7 +177,7 @@ impl<B, C> ControlFlow<B, C> {
     /// assert_eq!(ControlFlow::<String, i32>::Continue(3).break_value(), None);
     /// ```
     #[inline]
-    #[stable(feature = "control_flow_enum", since = "CURRENT_RUSTC_VERSION")]
+    #[stable(feature = "control_flow_enum", since = "1.83.0")]
     pub fn break_value(self) -> Option<B> {
         match self {
             ControlFlow::Continue(..) => None,
@@ -188,7 +188,7 @@ impl<B, C> ControlFlow<B, C> {
     /// Maps `ControlFlow<B, C>` to `ControlFlow<T, C>` by applying a function
     /// to the break value in case it exists.
     #[inline]
-    #[stable(feature = "control_flow_enum", since = "CURRENT_RUSTC_VERSION")]
+    #[stable(feature = "control_flow_enum", since = "1.83.0")]
     pub fn map_break<T>(self, f: impl FnOnce(B) -> T) -> ControlFlow<T, C> {
         match self {
             ControlFlow::Continue(x) => ControlFlow::Continue(x),
@@ -208,7 +208,7 @@ impl<B, C> ControlFlow<B, C> {
     /// assert_eq!(ControlFlow::<String, i32>::Continue(3).continue_value(), Some(3));
     /// ```
     #[inline]
-    #[stable(feature = "control_flow_enum", since = "CURRENT_RUSTC_VERSION")]
+    #[stable(feature = "control_flow_enum", since = "1.83.0")]
     pub fn continue_value(self) -> Option<C> {
         match self {
             ControlFlow::Continue(x) => Some(x),
@@ -219,7 +219,7 @@ impl<B, C> ControlFlow<B, C> {
     /// Maps `ControlFlow<B, C>` to `ControlFlow<B, T>` by applying a function
     /// to the continue value in case it exists.
     #[inline]
-    #[stable(feature = "control_flow_enum", since = "CURRENT_RUSTC_VERSION")]
+    #[stable(feature = "control_flow_enum", since = "1.83.0")]
     pub fn map_continue<T>(self, f: impl FnOnce(C) -> T) -> ControlFlow<B, T> {
         match self {
             ControlFlow::Continue(x) => ControlFlow::Continue(f(x)),
diff --git a/library/core/src/ops/unsize.rs b/library/core/src/ops/unsize.rs
index b51f12580ea..d2a07197f6f 100644
--- a/library/core/src/ops/unsize.rs
+++ b/library/core/src/ops/unsize.rs
@@ -68,8 +68,8 @@ impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *mut T {}
 #[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *const T {}
 
-/// `DispatchFromDyn` is used in the implementation of object safety checks (specifically allowing
-/// arbitrary self types), to guarantee that a method's receiver type can be dispatched on.
+/// `DispatchFromDyn` is used in the implementation of dyn-compatibility[^1] checks (specifically
+/// allowing arbitrary self types), to guarantee that a method's receiver type can be dispatched on.
 ///
 /// Note: `DispatchFromDyn` was briefly named `CoerceSized` (and had a slightly different
 /// interpretation).
@@ -80,7 +80,7 @@ impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *const T {}
 /// type). The compiler must generate an implicit conversion from the trait object/wide pointer to
 /// the concrete reference/narrow pointer. Implementing `DispatchFromDyn` indicates that that
 /// conversion is allowed and thus that the type implementing `DispatchFromDyn` is safe to use as
-/// the self type in an object-safe method. (in the above example, the compiler will require
+/// the self type in an dyn-compatible method. (in the above example, the compiler will require
 /// `DispatchFromDyn` is implemented for `&'a U`).
 ///
 /// `DispatchFromDyn` does not specify the conversion from wide pointer to narrow pointer; the
@@ -112,6 +112,8 @@ impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *const T {}
 ///     T: Unsize<U>,
 /// {}
 /// ```
+///
+/// [^1]: Formerly known as *object safety*.
 #[unstable(feature = "dispatch_from_dyn", issue = "none")]
 #[lang = "dispatch_from_dyn"]
 pub trait DispatchFromDyn<T> {
diff --git a/library/core/src/option.rs b/library/core/src/option.rs
index 154e52e288b..0b996c40c04 100644
--- a/library/core/src/option.rs
+++ b/library/core/src/option.rs
@@ -723,7 +723,7 @@ impl<T> Option<T> {
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_unstable(feature = "const_option", issue = "67441")]
+    #[rustc_const_stable(feature = "const_option", since = "1.83.0")]
     pub const fn as_mut(&mut self) -> Option<&mut T> {
         match *self {
             Some(ref mut x) => Some(x),
@@ -924,7 +924,8 @@ impl<T> Option<T> {
     #[track_caller]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[cfg_attr(not(test), rustc_diagnostic_item = "option_expect")]
-    #[rustc_const_unstable(feature = "const_option", issue = "67441")]
+    #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
+    #[rustc_const_stable(feature = "const_option", since = "1.83.0")]
     pub const fn expect(self, msg: &str) -> T {
         match self {
             Some(val) => val,
@@ -962,7 +963,8 @@ impl<T> Option<T> {
     #[track_caller]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[cfg_attr(not(test), rustc_diagnostic_item = "option_unwrap")]
-    #[rustc_const_unstable(feature = "const_option", issue = "67441")]
+    #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
+    #[rustc_const_stable(feature = "const_option", since = "1.83.0")]
     pub const fn unwrap(self) -> T {
         match self {
             Some(val) => val,
@@ -1069,7 +1071,8 @@ impl<T> Option<T> {
     #[inline]
     #[track_caller]
     #[stable(feature = "option_result_unwrap_unchecked", since = "1.58.0")]
-    #[rustc_const_unstable(feature = "const_option", issue = "67441")]
+    #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
+    #[rustc_const_stable(feature = "const_option", since = "1.83.0")]
     pub const unsafe fn unwrap_unchecked(self) -> T {
         match self {
             Some(val) => val,
@@ -1651,7 +1654,7 @@ impl<T> Option<T> {
     /// assert_eq!(x, Some(7));
     /// ```
     #[inline]
-    #[stable(feature = "option_get_or_insert_default", since = "CURRENT_RUSTC_VERSION")]
+    #[stable(feature = "option_get_or_insert_default", since = "1.83.0")]
     pub fn get_or_insert_default(&mut self) -> &mut T
     where
         T: Default,
@@ -1712,7 +1715,7 @@ impl<T> Option<T> {
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_unstable(feature = "const_option", issue = "67441")]
+    #[rustc_const_stable(feature = "const_option", since = "1.83.0")]
     pub const fn take(&mut self) -> Option<T> {
         // FIXME(const-hack) replace `mem::replace` by `mem::take` when the latter is const ready
         mem::replace(self, None)
@@ -1769,8 +1772,8 @@ impl<T> Option<T> {
     /// assert_eq!(old, None);
     /// ```
     #[inline]
-    #[rustc_const_unstable(feature = "const_option", issue = "67441")]
     #[stable(feature = "option_replace", since = "1.31.0")]
+    #[rustc_const_stable(feature = "const_option", since = "1.83.0")]
     pub const fn replace(&mut self, value: T) -> Option<T> {
         mem::replace(self, Some(value))
     }
@@ -1878,7 +1881,7 @@ impl<T> Option<&T> {
     /// ```
     #[must_use = "`self` will be dropped if the result is not used"]
     #[stable(feature = "copied", since = "1.35.0")]
-    #[rustc_const_unstable(feature = "const_option", issue = "67441")]
+    #[rustc_const_stable(feature = "const_option", since = "1.83.0")]
     pub const fn copied(self) -> Option<T>
     where
         T: Copy,
@@ -1931,7 +1934,7 @@ impl<T> Option<&mut T> {
     /// ```
     #[must_use = "`self` will be dropped if the result is not used"]
     #[stable(feature = "copied", since = "1.35.0")]
-    #[rustc_const_unstable(feature = "const_option", issue = "67441")]
+    #[rustc_const_stable(feature = "const_option", since = "1.83.0")]
     pub const fn copied(self) -> Option<T>
     where
         T: Copy,
@@ -1986,7 +1989,8 @@ impl<T, E> Option<Result<T, E>> {
     /// ```
     #[inline]
     #[stable(feature = "transpose_result", since = "1.33.0")]
-    #[rustc_const_unstable(feature = "const_option", issue = "67441")]
+    #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
+    #[rustc_const_stable(feature = "const_option", since = "1.83.0")]
     pub const fn transpose(self) -> Result<Option<T>, E> {
         match self {
             Some(Ok(x)) => Ok(Some(x)),
@@ -2009,7 +2013,6 @@ const fn unwrap_failed() -> ! {
 #[cfg_attr(feature = "panic_immediate_abort", inline)]
 #[cold]
 #[track_caller]
-#[rustc_const_unstable(feature = "const_option", issue = "67441")]
 const fn expect_failed(msg: &str) -> ! {
     panic_display(&msg)
 }
@@ -2534,7 +2537,8 @@ impl<T> Option<Option<T>> {
     /// ```
     #[inline]
     #[stable(feature = "option_flattening", since = "1.40.0")]
-    #[rustc_const_unstable(feature = "const_option", issue = "67441")]
+    #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
+    #[rustc_const_stable(feature = "const_option", since = "1.83.0")]
     pub const fn flatten(self) -> Option<T> {
         // FIXME(const-hack): could be written with `and_then`
         match self {
diff --git a/library/core/src/pin.rs b/library/core/src/pin.rs
index 9c13662e08e..fac789dbd99 100644
--- a/library/core/src/pin.rs
+++ b/library/core/src/pin.rs
@@ -1422,7 +1422,7 @@ impl<Ptr: DerefMut> Pin<Ptr> {
     /// move in the future, and this method does not enable the pointee to move. "Malicious"
     /// implementations of `Ptr::DerefMut` are likewise ruled out by the contract of
     /// `Pin::new_unchecked`.
-    #[unstable(feature = "pin_deref_mut", issue = "86918")]
+    #[stable(feature = "pin_deref_mut", since = "CURRENT_RUSTC_VERSION")]
     #[must_use = "`self` will be dropped if the result is not used"]
     #[inline(always)]
     pub fn as_deref_mut(self: Pin<&mut Pin<Ptr>>) -> Pin<&mut Ptr::Target> {
diff --git a/library/core/src/primitive_docs.rs b/library/core/src/primitive_docs.rs
index c25501f1200..89936dc12ac 100644
--- a/library/core/src/primitive_docs.rs
+++ b/library/core/src/primitive_docs.rs
@@ -862,6 +862,27 @@ mod prim_array {}
 /// assert_eq!(x, &[1, 7, 3]);
 /// ```
 ///
+/// It is possible to slice empty subranges of slices by using empty ranges (including `slice.len()..slice.len()`):
+/// ```
+/// let x = [1, 2, 3];
+/// let empty = &x[0..0];   // subslice before the first element
+/// assert_eq!(empty, &[]);
+/// let empty = &x[..0];    // same as &x[0..0]
+/// assert_eq!(empty, &[]);
+/// let empty = &x[1..1];   // empty subslice in the middle
+/// assert_eq!(empty, &[]);
+/// let empty = &x[3..3];   // subslice after the last element
+/// assert_eq!(empty, &[]);
+/// let empty = &x[3..];    // same as &x[3..3]
+/// assert_eq!(empty, &[]);
+/// ```
+///
+/// It is not allowed to use subranges that start with lower bound bigger than `slice.len()`:
+/// ```should_panic
+/// let x = vec![1, 2, 3];
+/// let _ = &x[4..4];
+/// ```
+///
 /// As slices store the length of the sequence they refer to, they have twice
 /// the size of pointers to [`Sized`](marker/trait.Sized.html) types.
 /// Also see the reference on
diff --git a/library/core/src/ptr/const_ptr.rs b/library/core/src/ptr/const_ptr.rs
index c9af7f13e46..72f4bc2c9da 100644
--- a/library/core/src/ptr/const_ptr.rs
+++ b/library/core/src/ptr/const_ptr.rs
@@ -63,21 +63,22 @@ impl<T: ?Sized> *const T {
         self as _
     }
 
-    /// Uses the pointer value in a new pointer of another type.
+    /// Uses the address value in a new pointer of another type.
     ///
-    /// In case `meta` is a (fat) pointer to an unsized type, this operation
-    /// will ignore the pointer part, whereas for (thin) pointers to sized
-    /// types, this has the same effect as a simple cast.
+    /// This operation will ignore the address part of its `meta` operand and discard existing
+    /// metadata of `self`. For pointers to a sized types (thin pointers), this has the same effect
+    /// as a simple cast. For pointers to an unsized type (fat pointers) this recombines the address
+    /// with new metadata such as slice lengths or `dyn`-vtable.
     ///
-    /// The resulting pointer will have provenance of `self`, i.e., for a fat
-    /// pointer, this operation is semantically the same as creating a new
-    /// fat pointer with the data pointer value of `self` but the metadata of
-    /// `meta`.
+    /// The resulting pointer will have provenance of `self`. This operation is semantically the
+    /// same as creating a new pointer with the data pointer value of `self` but the metadata of
+    /// `meta`, being fat or thin depending on the `meta` operand.
     ///
     /// # Examples
     ///
-    /// This function is primarily useful for allowing byte-wise pointer
-    /// arithmetic on potentially fat pointers:
+    /// This function is primarily useful for enabling pointer arithmetic on potentially fat
+    /// pointers. The pointer is cast to a sized pointee to utilize offset operations and then
+    /// recombined with its own original metadata.
     ///
     /// ```
     /// #![feature(set_ptr_value)]
@@ -91,8 +92,28 @@ impl<T: ?Sized> *const T {
     ///     println!("{:?}", &*ptr); // will print "3"
     /// }
     /// ```
+    ///
+    /// # *Incorrect* usage
+    ///
+    /// The provenance from pointers is *not* combined. The result must only be used to refer to the
+    /// address allowed by `self`.
+    ///
+    /// ```rust,no_run
+    /// #![feature(set_ptr_value)]
+    /// let x = 0u32;
+    /// let y = 1u32;
+    ///
+    /// let x = (&x) as *const u32;
+    /// let y = (&y) as *const u32;
+    ///
+    /// let offset = (x as usize - y as usize) / 4;
+    /// let bad = x.wrapping_add(offset).with_metadata_of(y);
+    ///
+    /// // This dereference is UB. The pointer only has provenance for `x` but points to `y`.
+    /// println!("{:?}", unsafe { &*bad });
+    /// ```
     #[unstable(feature = "set_ptr_value", issue = "75091")]
-    #[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "ptr_metadata_const", since = "1.83.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
     #[inline]
     pub const fn with_metadata_of<U>(self, meta: *const U) -> *const U
@@ -1278,7 +1299,7 @@ impl<T: ?Sized> *const T {
     /// See [`ptr::copy`] for safety concerns and examples.
     ///
     /// [`ptr::copy`]: crate::ptr::copy()
-    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.83.0")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
@@ -1298,7 +1319,7 @@ impl<T: ?Sized> *const T {
     /// See [`ptr::copy_nonoverlapping`] for safety concerns and examples.
     ///
     /// [`ptr::copy_nonoverlapping`]: crate::ptr::copy_nonoverlapping()
-    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.83.0")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
diff --git a/library/core/src/ptr/metadata.rs b/library/core/src/ptr/metadata.rs
index feeaf78d3e7..09c4002dbc7 100644
--- a/library/core/src/ptr/metadata.rs
+++ b/library/core/src/ptr/metadata.rs
@@ -92,7 +92,7 @@ pub trait Thin = Pointee<Metadata = ()>;
 ///
 /// assert_eq!(std::ptr::metadata("foo"), 3_usize);
 /// ```
-#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
+#[rustc_const_stable(feature = "ptr_metadata_const", since = "1.83.0")]
 #[inline]
 pub const fn metadata<T: ?Sized>(ptr: *const T) -> <T as Pointee>::Metadata {
     ptr_metadata(ptr)
@@ -106,7 +106,7 @@ pub const fn metadata<T: ?Sized>(ptr: *const T) -> <T as Pointee>::Metadata {
 ///
 /// [`slice::from_raw_parts`]: crate::slice::from_raw_parts
 #[unstable(feature = "ptr_metadata", issue = "81513")]
-#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
+#[rustc_const_stable(feature = "ptr_metadata_const", since = "1.83.0")]
 #[inline]
 pub const fn from_raw_parts<T: ?Sized>(
     data_pointer: *const impl Thin,
@@ -120,7 +120,7 @@ pub const fn from_raw_parts<T: ?Sized>(
 ///
 /// See the documentation of [`from_raw_parts`] for more details.
 #[unstable(feature = "ptr_metadata", issue = "81513")]
-#[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
+#[rustc_const_stable(feature = "ptr_metadata_const", since = "1.83.0")]
 #[inline]
 pub const fn from_raw_parts_mut<T: ?Sized>(
     data_pointer: *mut impl Thin,
diff --git a/library/core/src/ptr/mod.rs b/library/core/src/ptr/mod.rs
index 67f1b0cd16d..09ff7f8cab1 100644
--- a/library/core/src/ptr/mod.rs
+++ b/library/core/src/ptr/mod.rs
@@ -448,7 +448,7 @@
 
 use crate::cmp::Ordering;
 use crate::marker::FnPtr;
-use crate::mem::{self, MaybeUninit};
+use crate::mem::{self, MaybeUninit, SizedTypeProperties};
 use crate::{fmt, hash, intrinsics, ub_checks};
 
 mod alignment;
@@ -992,7 +992,7 @@ pub const fn slice_from_raw_parts<T>(data: *const T, len: usize) -> *const [T] {
 /// ```
 #[inline]
 #[stable(feature = "slice_from_raw_parts", since = "1.42.0")]
-#[rustc_const_stable(feature = "const_slice_from_raw_parts_mut", since = "CURRENT_RUSTC_VERSION")]
+#[rustc_const_stable(feature = "const_slice_from_raw_parts_mut", since = "1.83.0")]
 #[rustc_diagnostic_item = "ptr_slice_from_raw_parts_mut"]
 pub const fn slice_from_raw_parts_mut<T>(data: *mut T, len: usize) -> *mut [T] {
     from_raw_parts_mut(data, len)
@@ -1165,10 +1165,12 @@ pub const unsafe fn swap_nonoverlapping<T>(x: *mut T, y: *mut T, count: usize) {
             size: usize = size_of::<T>(),
             align: usize = align_of::<T>(),
             count: usize = count,
-        ) =>
-        ub_checks::is_aligned_and_not_null(x, align)
-            && ub_checks::is_aligned_and_not_null(y, align)
-            && ub_checks::is_nonoverlapping(x, y, size, count)
+        ) => {
+            let zero_size = size == 0 || count == 0;
+            ub_checks::is_aligned_and_not_null(x, align, zero_size)
+                && ub_checks::is_aligned_and_not_null(y, align, zero_size)
+                && ub_checks::is_nonoverlapping(x, y, size, count)
+        }
     );
 
     // Split up the slice into small power-of-two-sized chunks that LLVM is able
@@ -1263,7 +1265,7 @@ const unsafe fn swap_nonoverlapping_simple_untyped<T>(x: *mut T, y: *mut T, coun
 /// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[rustc_const_unstable(feature = "const_replace", issue = "83164")]
+#[rustc_const_stable(feature = "const_replace", since = "1.83.0")]
 #[rustc_diagnostic_item = "ptr_replace"]
 pub const unsafe fn replace<T>(dst: *mut T, src: T) -> T {
     // SAFETY: the caller must guarantee that `dst` is valid to be
@@ -1277,7 +1279,8 @@ pub const unsafe fn replace<T>(dst: *mut T, src: T) -> T {
             (
                 addr: *const () = dst as *const (),
                 align: usize = align_of::<T>(),
-            ) => ub_checks::is_aligned_and_not_null(addr, align)
+                is_zst: bool = T::IS_ZST,
+            ) => ub_checks::is_aligned_and_not_null(addr, align, is_zst)
         );
         mem::replace(&mut *dst, src)
     }
@@ -1429,7 +1432,8 @@ pub const unsafe fn read<T>(src: *const T) -> T {
             (
                 addr: *const () = src as *const (),
                 align: usize = align_of::<T>(),
-            ) => ub_checks::is_aligned_and_not_null(addr, align)
+                is_zst: bool = T::IS_ZST,
+            ) => ub_checks::is_aligned_and_not_null(addr, align, is_zst)
         );
         crate::intrinsics::read_via_copy(src)
     }
@@ -1513,7 +1517,6 @@ pub const unsafe fn read<T>(src: *const T) -> T {
 #[inline]
 #[stable(feature = "ptr_unaligned", since = "1.17.0")]
 #[rustc_const_stable(feature = "const_ptr_read", since = "1.71.0")]
-#[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 #[rustc_diagnostic_item = "ptr_read_unaligned"]
 pub const unsafe fn read_unaligned<T>(src: *const T) -> T {
@@ -1611,7 +1614,7 @@ pub const unsafe fn read_unaligned<T>(src: *const T) -> T {
 /// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+#[rustc_const_stable(feature = "const_ptr_write", since = "1.83.0")]
 #[rustc_diagnostic_item = "ptr_write"]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 pub const unsafe fn write<T>(dst: *mut T, src: T) {
@@ -1634,7 +1637,8 @@ pub const unsafe fn write<T>(dst: *mut T, src: T) {
             (
                 addr: *mut () = dst as *mut (),
                 align: usize = align_of::<T>(),
-            ) => ub_checks::is_aligned_and_not_null(addr, align)
+                is_zst: bool = T::IS_ZST,
+            ) => ub_checks::is_aligned_and_not_null(addr, align, is_zst)
         );
         intrinsics::write_via_move(dst, src)
     }
@@ -1719,7 +1723,7 @@ pub const unsafe fn write<T>(dst: *mut T, src: T) {
 /// ```
 #[inline]
 #[stable(feature = "ptr_unaligned", since = "1.17.0")]
-#[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+#[rustc_const_stable(feature = "const_ptr_write", since = "1.83.0")]
 #[rustc_diagnostic_item = "ptr_write_unaligned"]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 pub const unsafe fn write_unaligned<T>(dst: *mut T, src: T) {
@@ -1806,7 +1810,8 @@ pub unsafe fn read_volatile<T>(src: *const T) -> T {
             (
                 addr: *const () = src as *const (),
                 align: usize = align_of::<T>(),
-            ) => ub_checks::is_aligned_and_not_null(addr, align)
+                is_zst: bool = T::IS_ZST,
+            ) => ub_checks::is_aligned_and_not_null(addr, align, is_zst)
         );
         intrinsics::volatile_load(src)
     }
@@ -1885,7 +1890,8 @@ pub unsafe fn write_volatile<T>(dst: *mut T, src: T) {
             (
                 addr: *mut () = dst as *mut (),
                 align: usize = align_of::<T>(),
-            ) => ub_checks::is_aligned_and_not_null(addr, align)
+                is_zst: bool = T::IS_ZST,
+            ) => ub_checks::is_aligned_and_not_null(addr, align, is_zst)
         );
         intrinsics::volatile_store(dst, src);
     }
@@ -1909,7 +1915,7 @@ pub unsafe fn write_volatile<T>(dst: *mut T, src: T) {
 /// than trying to adapt this to accommodate that change.
 ///
 /// Any questions go to @nagisa.
-#[cfg_attr(not(bootstrap), allow(ptr_to_integer_transmute_in_consts))]
+#[allow(ptr_to_integer_transmute_in_consts)]
 #[lang = "align_offset"]
 pub(crate) const unsafe fn align_offset<T: Sized>(p: *const T, a: usize) -> usize {
     // FIXME(#75598): Direct use of these intrinsics improves codegen significantly at opt-level <=
diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs
index e458bb4642f..613d2c91ac6 100644
--- a/library/core/src/ptr/mut_ptr.rs
+++ b/library/core/src/ptr/mut_ptr.rs
@@ -45,21 +45,22 @@ impl<T: ?Sized> *mut T {
         self as _
     }
 
-    /// Uses the pointer value in a new pointer of another type.
+    /// Uses the address value in a new pointer of another type.
     ///
-    /// In case `meta` is a (fat) pointer to an unsized type, this operation
-    /// will ignore the pointer part, whereas for (thin) pointers to sized
-    /// types, this has the same effect as a simple cast.
+    /// This operation will ignore the address part of its `meta` operand and discard existing
+    /// metadata of `self`. For pointers to a sized types (thin pointers), this has the same effect
+    /// as a simple cast. For pointers to an unsized type (fat pointers) this recombines the address
+    /// with new metadata such as slice lengths or `dyn`-vtable.
     ///
-    /// The resulting pointer will have provenance of `self`, i.e., for a fat
-    /// pointer, this operation is semantically the same as creating a new
-    /// fat pointer with the data pointer value of `self` but the metadata of
-    /// `meta`.
+    /// The resulting pointer will have provenance of `self`. This operation is semantically the
+    /// same as creating a new pointer with the data pointer value of `self` but the metadata of
+    /// `meta`, being fat or thin depending on the `meta` operand.
     ///
     /// # Examples
     ///
-    /// This function is primarily useful for allowing byte-wise pointer
-    /// arithmetic on potentially fat pointers:
+    /// This function is primarily useful for enabling pointer arithmetic on potentially fat
+    /// pointers. The pointer is cast to a sized pointee to utilize offset operations and then
+    /// recombined with its own original metadata.
     ///
     /// ```
     /// #![feature(set_ptr_value)]
@@ -73,8 +74,27 @@ impl<T: ?Sized> *mut T {
     ///     println!("{:?}", &*ptr); // will print "3"
     /// }
     /// ```
+    ///
+    /// # *Incorrect* usage
+    ///
+    /// The provenance from pointers is *not* combined. The result must only be used to refer to the
+    /// address allowed by `self`.
+    ///
+    /// ```rust,no_run
+    /// #![feature(set_ptr_value)]
+    /// let mut x = 0u32;
+    /// let mut y = 1u32;
+    ///
+    /// let x = (&mut x) as *mut u32;
+    /// let y = (&mut y) as *mut u32;
+    ///
+    /// let offset = (x as usize - y as usize) / 4;
+    /// let bad = x.wrapping_add(offset).with_metadata_of(y);
+    ///
+    /// // This dereference is UB. The pointer only has provenance for `x` but points to `y`.
+    /// println!("{:?}", unsafe { &*bad });
     #[unstable(feature = "set_ptr_value", issue = "75091")]
-    #[rustc_const_stable(feature = "ptr_metadata_const", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "ptr_metadata_const", since = "1.83.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
     #[inline]
     pub const fn with_metadata_of<U>(self, meta: *const U) -> *mut U
@@ -1358,7 +1378,7 @@ impl<T: ?Sized> *mut T {
     /// See [`ptr::copy`] for safety concerns and examples.
     ///
     /// [`ptr::copy`]: crate::ptr::copy()
-    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.83.0")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
@@ -1378,7 +1398,7 @@ impl<T: ?Sized> *mut T {
     /// See [`ptr::copy_nonoverlapping`] for safety concerns and examples.
     ///
     /// [`ptr::copy_nonoverlapping`]: crate::ptr::copy_nonoverlapping()
-    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.83.0")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
@@ -1398,7 +1418,7 @@ impl<T: ?Sized> *mut T {
     /// See [`ptr::copy`] for safety concerns and examples.
     ///
     /// [`ptr::copy`]: crate::ptr::copy()
-    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.83.0")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
@@ -1418,7 +1438,7 @@ impl<T: ?Sized> *mut T {
     /// See [`ptr::copy_nonoverlapping`] for safety concerns and examples.
     ///
     /// [`ptr::copy_nonoverlapping`]: crate::ptr::copy_nonoverlapping()
-    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.83.0")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
@@ -1449,7 +1469,7 @@ impl<T: ?Sized> *mut T {
     ///
     /// [`ptr::write`]: crate::ptr::write()
     #[stable(feature = "pointer_methods", since = "1.26.0")]
-    #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[rustc_const_stable(feature = "const_ptr_write", since = "1.83.0")]
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     pub const unsafe fn write(self, val: T)
@@ -1468,7 +1488,7 @@ impl<T: ?Sized> *mut T {
     /// [`ptr::write_bytes`]: crate::ptr::write_bytes()
     #[doc(alias = "memset")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
-    #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[rustc_const_stable(feature = "const_ptr_write", since = "1.83.0")]
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     pub const unsafe fn write_bytes(self, val: u8, count: usize)
@@ -1509,7 +1529,7 @@ impl<T: ?Sized> *mut T {
     ///
     /// [`ptr::write_unaligned`]: crate::ptr::write_unaligned()
     #[stable(feature = "pointer_methods", since = "1.26.0")]
-    #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[rustc_const_stable(feature = "const_ptr_write", since = "1.83.0")]
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     pub const unsafe fn write_unaligned(self, val: T)
@@ -1658,7 +1678,6 @@ impl<T: ?Sized> *mut T {
     ///
     /// ```
     /// #![feature(const_pointer_is_aligned)]
-    /// # #![cfg_attr(bootstrap, feature(const_mut_refs))]
     ///
     /// // On some platforms, the alignment of primitives is less than their size.
     /// #[repr(align(4))]
@@ -1784,7 +1803,6 @@ impl<T: ?Sized> *mut T {
     /// ```
     /// #![feature(pointer_is_aligned_to)]
     /// #![feature(const_pointer_is_aligned)]
-    /// # #![cfg_attr(bootstrap, feature(const_mut_refs))]
     ///
     /// // On some platforms, the alignment of i32 is less than 4.
     /// #[repr(align(4))]
diff --git a/library/core/src/ptr/non_null.rs b/library/core/src/ptr/non_null.rs
index 6c5834a1ece..3e4cae2b3ca 100644
--- a/library/core/src/ptr/non_null.rs
+++ b/library/core/src/ptr/non_null.rs
@@ -230,6 +230,24 @@ impl<T: ?Sized> NonNull<T> {
         }
     }
 
+    /// Converts a reference to a `NonNull` pointer.
+    #[unstable(feature = "non_null_from_ref", issue = "130823")]
+    #[rustc_const_unstable(feature = "non_null_from_ref", issue = "130823")]
+    #[inline]
+    pub const fn from_ref(r: &T) -> Self {
+        // SAFETY: A reference cannot be null.
+        unsafe { NonNull { pointer: r as *const T } }
+    }
+
+    /// Converts a mutable reference to a `NonNull` pointer.
+    #[unstable(feature = "non_null_from_ref", issue = "130823")]
+    #[rustc_const_unstable(feature = "non_null_from_ref", issue = "130823")]
+    #[inline]
+    pub const fn from_mut(r: &mut T) -> Self {
+        // SAFETY: A mutable reference cannot be null.
+        unsafe { NonNull { pointer: r as *mut T } }
+    }
+
     /// Performs the same functionality as [`std::ptr::from_raw_parts`], except that a
     /// `NonNull` pointer is returned, as opposed to a raw `*const` pointer.
     ///
@@ -394,8 +412,7 @@ impl<T: ?Sized> NonNull<T> {
     ///
     /// [the module documentation]: crate::ptr#safety
     #[stable(feature = "nonnull", since = "1.25.0")]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
-    #[rustc_const_stable(feature = "const_ptr_as_ref", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_ptr_as_ref", since = "1.83.0")]
     #[must_use]
     #[inline(always)]
     pub const unsafe fn as_mut<'a>(&mut self) -> &'a mut T {
@@ -923,7 +940,7 @@ impl<T: ?Sized> NonNull<T> {
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     #[stable(feature = "non_null_convenience", since = "1.80.0")]
-    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.83.0")]
     pub const unsafe fn copy_to(self, dest: NonNull<T>, count: usize)
     where
         T: Sized,
@@ -943,7 +960,7 @@ impl<T: ?Sized> NonNull<T> {
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     #[stable(feature = "non_null_convenience", since = "1.80.0")]
-    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.83.0")]
     pub const unsafe fn copy_to_nonoverlapping(self, dest: NonNull<T>, count: usize)
     where
         T: Sized,
@@ -963,7 +980,7 @@ impl<T: ?Sized> NonNull<T> {
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     #[stable(feature = "non_null_convenience", since = "1.80.0")]
-    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.83.0")]
     pub const unsafe fn copy_from(self, src: NonNull<T>, count: usize)
     where
         T: Sized,
@@ -983,7 +1000,7 @@ impl<T: ?Sized> NonNull<T> {
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     #[stable(feature = "non_null_convenience", since = "1.80.0")]
-    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.83.0")]
     pub const unsafe fn copy_from_nonoverlapping(self, src: NonNull<T>, count: usize)
     where
         T: Sized,
@@ -1013,7 +1030,7 @@ impl<T: ?Sized> NonNull<T> {
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     #[stable(feature = "non_null_convenience", since = "1.80.0")]
-    #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[rustc_const_stable(feature = "const_ptr_write", since = "1.83.0")]
     pub const unsafe fn write(self, val: T)
     where
         T: Sized,
@@ -1032,7 +1049,7 @@ impl<T: ?Sized> NonNull<T> {
     #[doc(alias = "memset")]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     #[stable(feature = "non_null_convenience", since = "1.80.0")]
-    #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[rustc_const_stable(feature = "const_ptr_write", since = "1.83.0")]
     pub const unsafe fn write_bytes(self, val: u8, count: usize)
     where
         T: Sized,
@@ -1073,7 +1090,7 @@ impl<T: ?Sized> NonNull<T> {
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     #[stable(feature = "non_null_convenience", since = "1.80.0")]
-    #[rustc_const_unstable(feature = "const_ptr_write", issue = "86302")]
+    #[rustc_const_stable(feature = "const_ptr_write", since = "1.83.0")]
     pub const unsafe fn write_unaligned(self, val: T)
     where
         T: Sized,
@@ -1211,7 +1228,6 @@ impl<T: ?Sized> NonNull<T> {
     ///
     /// ```
     /// #![feature(const_nonnull_new)]
-    /// #![feature(const_option)]
     /// #![feature(const_pointer_is_aligned)]
     /// use std::ptr::NonNull;
     ///
@@ -1264,7 +1280,6 @@ impl<T: ?Sized> NonNull<T> {
     ///
     /// ```
     /// #![feature(const_pointer_is_aligned)]
-    /// #![feature(const_option)]
     /// #![feature(const_nonnull_new)]
     /// use std::ptr::NonNull;
     ///
@@ -1434,10 +1449,7 @@ impl<T> NonNull<[T]> {
     /// (Note that this example artificially demonstrates a use of this method,
     /// but `let slice = NonNull::from(&x[..]);` would be a better way to write code like this.)
     #[stable(feature = "nonnull_slice_from_raw_parts", since = "1.70.0")]
-    #[rustc_const_stable(
-        feature = "const_slice_from_raw_parts_mut",
-        since = "CURRENT_RUSTC_VERSION"
-    )]
+    #[rustc_const_stable(feature = "const_slice_from_raw_parts_mut", since = "1.83.0")]
     #[must_use]
     #[inline]
     pub const fn slice_from_raw_parts(data: NonNull<T>, len: usize) -> Self {
@@ -1755,9 +1767,8 @@ impl<T: ?Sized> From<&mut T> for NonNull<T> {
     ///
     /// This conversion is safe and infallible since references cannot be null.
     #[inline]
-    fn from(reference: &mut T) -> Self {
-        // SAFETY: A mutable reference cannot be null.
-        unsafe { NonNull { pointer: reference as *mut T } }
+    fn from(r: &mut T) -> Self {
+        NonNull::from_mut(r)
     }
 }
 
@@ -1767,8 +1778,7 @@ impl<T: ?Sized> From<&T> for NonNull<T> {
     ///
     /// This conversion is safe and infallible since references cannot be null.
     #[inline]
-    fn from(reference: &T) -> Self {
-        // SAFETY: A reference cannot be null.
-        unsafe { NonNull { pointer: reference as *const T } }
+    fn from(r: &T) -> Self {
+        NonNull::from_ref(r)
     }
 }
diff --git a/library/core/src/result.rs b/library/core/src/result.rs
index 610edae48d3..330d1eb14ed 100644
--- a/library/core/src/result.rs
+++ b/library/core/src/result.rs
@@ -734,7 +734,7 @@ impl<T, E> Result<T, E> {
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_unstable(feature = "const_result", issue = "82814")]
+    #[rustc_const_stable(feature = "const_result", since = "1.83.0")]
     pub const fn as_mut(&mut self) -> Result<&mut T, &mut E> {
         match *self {
             Ok(ref mut x) => Ok(x),
@@ -1536,7 +1536,8 @@ impl<T, E> Result<&T, E> {
     /// ```
     #[inline]
     #[stable(feature = "result_copied", since = "1.59.0")]
-    #[rustc_const_unstable(feature = "const_result", issue = "82814")]
+    #[rustc_const_stable(feature = "const_result", since = "1.83.0")]
+    #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
     pub const fn copied(self) -> Result<T, E>
     where
         T: Copy,
@@ -1586,7 +1587,8 @@ impl<T, E> Result<&mut T, E> {
     /// ```
     #[inline]
     #[stable(feature = "result_copied", since = "1.59.0")]
-    #[rustc_const_unstable(feature = "const_result", issue = "82814")]
+    #[rustc_const_stable(feature = "const_result", since = "1.83.0")]
+    #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
     pub const fn copied(self) -> Result<T, E>
     where
         T: Copy,
@@ -1639,7 +1641,8 @@ impl<T, E> Result<Option<T>, E> {
     /// ```
     #[inline]
     #[stable(feature = "transpose_result", since = "1.33.0")]
-    #[rustc_const_unstable(feature = "const_result", issue = "82814")]
+    #[rustc_const_stable(feature = "const_result", since = "1.83.0")]
+    #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
     pub const fn transpose(self) -> Option<Result<T, E>> {
         match self {
             Ok(Some(x)) => Some(Ok(x)),
diff --git a/library/core/src/slice/ascii.rs b/library/core/src/slice/ascii.rs
index 8f8050fdc3a..a03e9fbae11 100644
--- a/library/core/src/slice/ascii.rs
+++ b/library/core/src/slice/ascii.rs
@@ -67,7 +67,7 @@ impl [u8] {
     ///
     /// [`to_ascii_uppercase`]: #method.to_ascii_uppercase
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
-    #[rustc_const_unstable(feature = "const_make_ascii", issue = "130698")]
+    #[rustc_const_stable(feature = "const_make_ascii", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn make_ascii_uppercase(&mut self) {
         // FIXME(const-hack): We would like to simply iterate using `for` loops but this isn't currently allowed in constant expressions.
@@ -89,7 +89,7 @@ impl [u8] {
     ///
     /// [`to_ascii_lowercase`]: #method.to_ascii_lowercase
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
-    #[rustc_const_unstable(feature = "const_make_ascii", issue = "130698")]
+    #[rustc_const_stable(feature = "const_make_ascii", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn make_ascii_lowercase(&mut self) {
         // FIXME(const-hack): We would like to simply iterate using `for` loops but this isn't currently allowed in constant expressions.
diff --git a/library/core/src/slice/mod.rs b/library/core/src/slice/mod.rs
index 90ddc9c1d85..dbcfe946440 100644
--- a/library/core/src/slice/mod.rs
+++ b/library/core/src/slice/mod.rs
@@ -171,8 +171,7 @@ impl<T> [T] {
     /// assert_eq!(None, y.first_mut());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
-    #[rustc_const_stable(feature = "const_slice_first_last", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_slice_first_last", since = "1.83.0")]
     #[inline]
     #[must_use]
     pub const fn first_mut(&mut self) -> Option<&mut T> {
@@ -214,8 +213,7 @@ impl<T> [T] {
     /// assert_eq!(x, &[3, 4, 5]);
     /// ```
     #[stable(feature = "slice_splits", since = "1.5.0")]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
-    #[rustc_const_stable(feature = "const_slice_first_last", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_slice_first_last", since = "1.83.0")]
     #[inline]
     #[must_use]
     pub const fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])> {
@@ -257,8 +255,7 @@ impl<T> [T] {
     /// assert_eq!(x, &[4, 5, 3]);
     /// ```
     #[stable(feature = "slice_splits", since = "1.5.0")]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
-    #[rustc_const_stable(feature = "const_slice_first_last", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_slice_first_last", since = "1.83.0")]
     #[inline]
     #[must_use]
     pub const fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])> {
@@ -300,8 +297,7 @@ impl<T> [T] {
     /// assert_eq!(None, y.last_mut());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
-    #[rustc_const_stable(feature = "const_slice_first_last", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_slice_first_last", since = "1.83.0")]
     #[inline]
     #[must_use]
     pub const fn last_mut(&mut self) -> Option<&mut T> {
@@ -356,8 +352,7 @@ impl<T> [T] {
     /// ```
     #[inline]
     #[stable(feature = "slice_first_last_chunk", since = "1.77.0")]
-    #[rustc_const_stable(feature = "const_slice_first_last_chunk", since = "CURRENT_RUSTC_VERSION")]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
+    #[rustc_const_stable(feature = "const_slice_first_last_chunk", since = "1.83.0")]
     pub const fn first_chunk_mut<const N: usize>(&mut self) -> Option<&mut [T; N]> {
         if self.len() < N {
             None
@@ -422,8 +417,7 @@ impl<T> [T] {
     /// ```
     #[inline]
     #[stable(feature = "slice_first_last_chunk", since = "1.77.0")]
-    #[rustc_const_stable(feature = "const_slice_first_last_chunk", since = "CURRENT_RUSTC_VERSION")]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
+    #[rustc_const_stable(feature = "const_slice_first_last_chunk", since = "1.83.0")]
     pub const fn split_first_chunk_mut<const N: usize>(
         &mut self,
     ) -> Option<(&mut [T; N], &mut [T])> {
@@ -493,8 +487,7 @@ impl<T> [T] {
     /// ```
     #[inline]
     #[stable(feature = "slice_first_last_chunk", since = "1.77.0")]
-    #[rustc_const_stable(feature = "const_slice_first_last_chunk", since = "CURRENT_RUSTC_VERSION")]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
+    #[rustc_const_stable(feature = "const_slice_first_last_chunk", since = "1.83.0")]
     pub const fn split_last_chunk_mut<const N: usize>(
         &mut self,
     ) -> Option<(&mut [T], &mut [T; N])> {
@@ -563,8 +556,7 @@ impl<T> [T] {
     /// ```
     #[inline]
     #[stable(feature = "slice_first_last_chunk", since = "1.77.0")]
-    #[rustc_const_stable(feature = "const_slice_first_last_chunk", since = "CURRENT_RUSTC_VERSION")]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
+    #[rustc_const_stable(feature = "const_slice_first_last_chunk", since = "1.83.0")]
     pub const fn last_chunk_mut<const N: usize>(&mut self) -> Option<&mut [T; N]> {
         if self.len() < N {
             None
@@ -853,7 +845,6 @@ impl<T> [T] {
     /// [`as_mut_ptr`]: slice::as_mut_ptr
     #[stable(feature = "slice_ptr_range", since = "1.48.0")]
     #[rustc_const_stable(feature = "const_ptr_offset", since = "1.61.0")]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs, const_refs_to_cell))]
     #[inline]
     #[must_use]
     pub const fn as_mut_ptr_range(&mut self) -> Range<*mut T> {
@@ -1907,8 +1898,7 @@ impl<T> [T] {
     #[inline]
     #[track_caller]
     #[must_use]
-    #[rustc_const_stable(feature = "const_slice_split_at_mut", since = "CURRENT_RUSTC_VERSION")]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
+    #[rustc_const_stable(feature = "const_slice_split_at_mut", since = "1.83.0")]
     pub const fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T]) {
         match self.split_at_mut_checked(mid) {
             Some(pair) => pair,
@@ -2010,8 +2000,7 @@ impl<T> [T] {
     /// assert_eq!(v, [1, 2, 3, 4, 5, 6]);
     /// ```
     #[stable(feature = "slice_split_at_unchecked", since = "1.79.0")]
-    #[rustc_const_stable(feature = "const_slice_split_at_mut", since = "CURRENT_RUSTC_VERSION")]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
+    #[rustc_const_stable(feature = "const_slice_split_at_mut", since = "1.83.0")]
     #[inline]
     #[must_use]
     pub const unsafe fn split_at_mut_unchecked(&mut self, mid: usize) -> (&mut [T], &mut [T]) {
@@ -2111,8 +2100,7 @@ impl<T> [T] {
     /// assert_eq!(None, v.split_at_mut_checked(7));
     /// ```
     #[stable(feature = "split_at_checked", since = "1.80.0")]
-    #[rustc_const_stable(feature = "const_slice_split_at_mut", since = "CURRENT_RUSTC_VERSION")]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
+    #[rustc_const_stable(feature = "const_slice_split_at_mut", since = "1.83.0")]
     #[inline]
     #[must_use]
     pub const fn split_at_mut_checked(&mut self, mid: usize) -> Option<(&mut [T], &mut [T])> {
diff --git a/library/core/src/slice/raw.rs b/library/core/src/slice/raw.rs
index 84e916b9a84..89840881c4d 100644
--- a/library/core/src/slice/raw.rs
+++ b/library/core/src/slice/raw.rs
@@ -132,7 +132,7 @@ pub const unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T]
                 align: usize = align_of::<T>(),
                 len: usize = len,
             ) =>
-            ub_checks::is_aligned_and_not_null(data, align)
+            ub_checks::is_aligned_and_not_null(data, align, false)
                 && ub_checks::is_valid_allocation_size(size, len)
         );
         &*ptr::slice_from_raw_parts(data, len)
@@ -171,8 +171,7 @@ pub const unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T]
 /// [`NonNull::dangling()`]: ptr::NonNull::dangling
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[rustc_const_stable(feature = "const_slice_from_raw_parts_mut", since = "CURRENT_RUSTC_VERSION")]
-#[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
+#[rustc_const_stable(feature = "const_slice_from_raw_parts_mut", since = "1.83.0")]
 #[must_use]
 #[rustc_diagnostic_item = "slice_from_raw_parts_mut"]
 pub const unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a mut [T] {
@@ -187,7 +186,7 @@ pub const unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a m
                 align: usize = align_of::<T>(),
                 len: usize = len,
             ) =>
-            ub_checks::is_aligned_and_not_null(data, align)
+            ub_checks::is_aligned_and_not_null(data, align, false)
                 && ub_checks::is_valid_allocation_size(size, len)
         );
         &mut *ptr::slice_from_raw_parts_mut(data, len)
@@ -204,7 +203,7 @@ pub const fn from_ref<T>(s: &T) -> &[T] {
 
 /// Converts a reference to T into a slice of length 1 (without copying).
 #[stable(feature = "from_ref", since = "1.28.0")]
-#[rustc_const_unstable(feature = "const_slice_from_ref", issue = "90206")]
+#[rustc_const_stable(feature = "const_slice_from_ref", since = "1.83.0")]
 #[must_use]
 pub const fn from_mut<T>(s: &mut T) -> &mut [T] {
     array::from_mut(s)
diff --git a/library/core/src/str/converts.rs b/library/core/src/str/converts.rs
index 194db56fdaf..c997e5e443d 100644
--- a/library/core/src/str/converts.rs
+++ b/library/core/src/str/converts.rs
@@ -195,11 +195,7 @@ pub const unsafe fn from_utf8_unchecked(v: &[u8]) -> &str {
 #[inline]
 #[must_use]
 #[stable(feature = "str_mut_extras", since = "1.20.0")]
-#[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
-#[rustc_const_stable(
-    feature = "const_str_from_utf8_unchecked_mut",
-    since = "CURRENT_RUSTC_VERSION"
-)]
+#[rustc_const_stable(feature = "const_str_from_utf8_unchecked_mut", since = "1.83.0")]
 #[rustc_diagnostic_item = "str_from_utf8_unchecked_mut"]
 pub const unsafe fn from_utf8_unchecked_mut(v: &mut [u8]) -> &mut str {
     // SAFETY: the caller must guarantee that the bytes `v`
diff --git a/library/core/src/str/mod.rs b/library/core/src/str/mod.rs
index e93c52f2799..89addc4cb74 100644
--- a/library/core/src/str/mod.rs
+++ b/library/core/src/str/mod.rs
@@ -339,8 +339,7 @@ impl str {
     /// assert_eq!("🍔∈🌏", s);
     /// ```
     #[stable(feature = "str_mut_extras", since = "1.20.0")]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
-    #[rustc_const_stable(feature = "const_str_as_mut", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_str_as_mut", since = "1.83.0")]
     #[must_use]
     #[inline(always)]
     pub const unsafe fn as_bytes_mut(&mut self) -> &mut [u8] {
@@ -386,8 +385,7 @@ impl str {
     /// It is your responsibility to make sure that the string slice only gets
     /// modified in a way that it remains valid UTF-8.
     #[stable(feature = "str_as_mut_ptr", since = "1.36.0")]
-    #[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
-    #[rustc_const_stable(feature = "const_str_as_mut", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "const_str_as_mut", since = "1.83.0")]
     #[rustc_never_returns_null_ptr]
     #[must_use]
     #[inline(always)]
@@ -2475,7 +2473,7 @@ impl str {
     /// assert_eq!("GRüßE, JüRGEN ❤", s);
     /// ```
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
-    #[rustc_const_unstable(feature = "const_make_ascii", issue = "130698")]
+    #[rustc_const_stable(feature = "const_make_ascii", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn make_ascii_uppercase(&mut self) {
         // SAFETY: changing ASCII letters only does not invalidate UTF-8.
@@ -2503,7 +2501,7 @@ impl str {
     /// assert_eq!("grÜße, jÜrgen ❤", s);
     /// ```
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
-    #[rustc_const_unstable(feature = "const_make_ascii", issue = "130698")]
+    #[rustc_const_stable(feature = "const_make_ascii", since = "CURRENT_RUSTC_VERSION")]
     #[inline]
     pub const fn make_ascii_lowercase(&mut self) {
         // SAFETY: changing ASCII letters only does not invalidate UTF-8.
diff --git a/library/core/src/task/wake.rs b/library/core/src/task/wake.rs
index fc549abd433..3e795e7b5e3 100644
--- a/library/core/src/task/wake.rs
+++ b/library/core/src/task/wake.rs
@@ -519,8 +519,8 @@ impl Waker {
     /// [`Wake`]: ../../alloc/task/trait.Wake.html
     #[inline]
     #[must_use]
-    #[stable(feature = "waker_getters", since = "CURRENT_RUSTC_VERSION")]
-    #[rustc_const_stable(feature = "waker_getters", since = "CURRENT_RUSTC_VERSION")]
+    #[stable(feature = "waker_getters", since = "1.83.0")]
+    #[rustc_const_stable(feature = "waker_getters", since = "1.83.0")]
     pub const unsafe fn new(data: *const (), vtable: &'static RawWakerVTable) -> Self {
         Waker { waker: RawWaker { data, vtable } }
     }
@@ -584,7 +584,7 @@ impl Waker {
     /// Gets the `data` pointer used to create this `Waker`.
     #[inline]
     #[must_use]
-    #[stable(feature = "waker_getters", since = "CURRENT_RUSTC_VERSION")]
+    #[stable(feature = "waker_getters", since = "1.83.0")]
     pub fn data(&self) -> *const () {
         self.waker.data
     }
@@ -592,7 +592,7 @@ impl Waker {
     /// Gets the `vtable` pointer used to create this `Waker`.
     #[inline]
     #[must_use]
-    #[stable(feature = "waker_getters", since = "CURRENT_RUSTC_VERSION")]
+    #[stable(feature = "waker_getters", since = "1.83.0")]
     pub fn vtable(&self) -> &'static RawWakerVTable {
         self.waker.vtable
     }
diff --git a/library/core/src/time.rs b/library/core/src/time.rs
index 65560dfcf9d..5081e777af4 100644
--- a/library/core/src/time.rs
+++ b/library/core/src/time.rs
@@ -213,11 +213,9 @@ impl Duration {
             // SAFETY: nanos < NANOS_PER_SEC, therefore nanos is within the valid range
             Duration { secs, nanos: unsafe { Nanoseconds(nanos) } }
         } else {
-            // FIXME(const-hack): use `.expect` once that is possible.
-            let secs = match secs.checked_add((nanos / NANOS_PER_SEC) as u64) {
-                Some(secs) => secs,
-                None => panic!("overflow in Duration::new"),
-            };
+            let secs = secs
+                .checked_add((nanos / NANOS_PER_SEC) as u64)
+                .expect("overflow in Duration::new");
             let nanos = nanos % NANOS_PER_SEC;
             // SAFETY: nanos % NANOS_PER_SEC < NANOS_PER_SEC, therefore nanos is within the valid range
             Duration { secs, nanos: unsafe { Nanoseconds(nanos) } }
@@ -626,7 +624,6 @@ impl Duration {
     /// ```
     #[stable(feature = "duration_abs_diff", since = "1.81.0")]
     #[rustc_const_stable(feature = "duration_abs_diff", since = "1.81.0")]
-    #[rustc_allow_const_fn_unstable(const_option)]
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[inline]
@@ -847,7 +844,7 @@ impl Duration {
     #[stable(feature = "duration_float", since = "1.38.0")]
     #[must_use]
     #[inline]
-    #[rustc_const_unstable(feature = "duration_consts_float", issue = "72440")]
+    #[rustc_const_stable(feature = "duration_consts_float", since = "1.83.0")]
     pub const fn as_secs_f64(&self) -> f64 {
         (self.secs as f64) + (self.nanos.0 as f64) / (NANOS_PER_SEC as f64)
     }
@@ -866,7 +863,7 @@ impl Duration {
     #[stable(feature = "duration_float", since = "1.38.0")]
     #[must_use]
     #[inline]
-    #[rustc_const_unstable(feature = "duration_consts_float", issue = "72440")]
+    #[rustc_const_stable(feature = "duration_consts_float", since = "1.83.0")]
     pub const fn as_secs_f32(&self) -> f32 {
         (self.secs as f32) + (self.nanos.0 as f32) / (NANOS_PER_SEC as f32)
     }
@@ -886,7 +883,7 @@ impl Duration {
     #[unstable(feature = "duration_millis_float", issue = "122451")]
     #[must_use]
     #[inline]
-    #[rustc_const_unstable(feature = "duration_consts_float", issue = "72440")]
+    #[rustc_const_unstable(feature = "duration_millis_float", issue = "122451")]
     pub const fn as_millis_f64(&self) -> f64 {
         (self.secs as f64) * (MILLIS_PER_SEC as f64)
             + (self.nanos.0 as f64) / (NANOS_PER_MILLI as f64)
@@ -907,7 +904,7 @@ impl Duration {
     #[unstable(feature = "duration_millis_float", issue = "122451")]
     #[must_use]
     #[inline]
-    #[rustc_const_unstable(feature = "duration_consts_float", issue = "72440")]
+    #[rustc_const_unstable(feature = "duration_millis_float", issue = "122451")]
     pub const fn as_millis_f32(&self) -> f32 {
         (self.secs as f32) * (MILLIS_PER_SEC as f32)
             + (self.nanos.0 as f32) / (NANOS_PER_MILLI as f32)
@@ -1087,7 +1084,7 @@ impl Duration {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[inline]
-    #[rustc_const_unstable(feature = "duration_consts_float", issue = "72440")]
+    #[rustc_const_stable(feature = "duration_consts_float", since = "1.83.0")]
     pub const fn div_duration_f64(self, rhs: Duration) -> f64 {
         let self_nanos = (self.secs as f64) * (NANOS_PER_SEC as f64) + (self.nanos.0 as f64);
         let rhs_nanos = (rhs.secs as f64) * (NANOS_PER_SEC as f64) + (rhs.nanos.0 as f64);
@@ -1108,7 +1105,7 @@ impl Duration {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[inline]
-    #[rustc_const_unstable(feature = "duration_consts_float", issue = "72440")]
+    #[rustc_const_stable(feature = "duration_consts_float", since = "1.83.0")]
     pub const fn div_duration_f32(self, rhs: Duration) -> f32 {
         let self_nanos = (self.secs as f32) * (NANOS_PER_SEC as f32) + (self.nanos.0 as f32);
         let rhs_nanos = (rhs.secs as f32) * (NANOS_PER_SEC as f32) + (rhs.nanos.0 as f32);
diff --git a/library/core/src/ub_checks.rs b/library/core/src/ub_checks.rs
index c1a8c34539e..daaaf5a7195 100644
--- a/library/core/src/ub_checks.rs
+++ b/library/core/src/ub_checks.rs
@@ -109,15 +109,15 @@ pub(crate) const fn check_language_ub() -> bool {
     intrinsics::ub_checks() && const_eval_select((), comptime, runtime)
 }
 
-/// Checks whether `ptr` is properly aligned with respect to
-/// `align_of::<T>()`.
+/// Checks whether `ptr` is properly aligned with respect to the given alignment, and
+/// if `is_zst == false`, that `ptr` is not null.
 ///
 /// In `const` this is approximate and can fail spuriously. It is primarily intended
 /// for `assert_unsafe_precondition!` with `check_language_ub`, in which case the
 /// check is anyway not executed in `const`.
 #[inline]
-pub(crate) const fn is_aligned_and_not_null(ptr: *const (), align: usize) -> bool {
-    !ptr.is_null() && ptr.is_aligned_to(align)
+pub(crate) const fn is_aligned_and_not_null(ptr: *const (), align: usize, is_zst: bool) -> bool {
+    ptr.is_aligned_to(align) && (is_zst || !ptr.is_null())
 }
 
 #[inline]
diff --git a/library/core/src/unicode/unicode_data.rs b/library/core/src/unicode/unicode_data.rs
index db2e3ddd754..cba53bf5054 100644
--- a/library/core/src/unicode/unicode_data.rs
+++ b/library/core/src/unicode/unicode_data.rs
@@ -331,14 +331,14 @@ pub mod grapheme_extend {
 
 #[rustfmt::skip]
 pub mod lowercase {
-    const BITSET_CHUNKS_MAP: &'static [u8; 123] = &[
+    static BITSET_CHUNKS_MAP: [u8; 123] = [
         14, 17, 0, 0, 9, 0, 0, 12, 13, 10, 0, 16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
         0, 0, 0, 4, 1, 0, 15, 0, 8, 0, 0, 11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
         0, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 19, 0,
         3, 18, 0, 7,
     ];
-    const BITSET_INDEX_CHUNKS: &'static [[u8; 16]; 20] = &[
+    static BITSET_INDEX_CHUNKS: [[u8; 16]; 20] = [
         [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
         [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 61, 0, 0],
         [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 16, 14, 56, 0],
@@ -360,7 +360,7 @@ pub mod lowercase {
         [16, 72, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
         [65, 41, 55, 12, 77, 63, 18, 1, 7, 64, 76, 20, 73, 74, 4, 45],
     ];
-    const BITSET_CANONICAL: &'static [u64; 56] = &[
+    static BITSET_CANONICAL: [u64; 56] = [
         0b0000000000000000000000000000000000000000000000000000000000000000,
         0b1111111111111111110000000000000000000000000011111111111111111111,
         0b1010101010101010101010101010101010101010101010101010100000000010,
@@ -418,7 +418,7 @@ pub mod lowercase {
         0b1110011001010001001011010010101001001110001001000011000100101001,
         0b1110101111000000000000000000000000001111111111111111111111111100,
     ];
-    const BITSET_MAPPING: &'static [(u8, u8); 22] = &[
+    static BITSET_MAPPING: [(u8, u8); 22] = [
         (0, 64), (1, 188), (1, 186), (1, 183), (1, 176), (1, 109), (1, 124), (1, 126), (1, 66),
         (1, 70), (1, 77), (2, 146), (2, 144), (2, 83), (3, 93), (3, 147), (3, 133), (4, 12), (4, 6),
         (5, 187), (6, 78), (7, 132),
@@ -471,14 +471,14 @@ pub mod n {
 
 #[rustfmt::skip]
 pub mod uppercase {
-    const BITSET_CHUNKS_MAP: &'static [u8; 125] = &[
+    static BITSET_CHUNKS_MAP: [u8; 125] = [
         12, 15, 6, 6, 0, 6, 6, 2, 4, 11, 6, 16, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
         6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 8, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
         6, 6, 6, 5, 6, 14, 6, 10, 6, 6, 1, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
         6, 7, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 13, 6, 6,
         6, 6, 9, 6, 3,
     ];
-    const BITSET_INDEX_CHUNKS: &'static [[u8; 16]; 17] = &[
+    static BITSET_INDEX_CHUNKS: [[u8; 16]; 17] = [
         [44, 44, 5, 35, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 5, 1],
         [44, 44, 5, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44],
         [44, 44, 40, 44, 44, 44, 44, 44, 17, 17, 63, 17, 43, 29, 24, 23],
@@ -497,7 +497,7 @@ pub mod uppercase {
         [58, 19, 2, 18, 10, 48, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44],
         [58, 38, 17, 27, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44],
     ];
-    const BITSET_CANONICAL: &'static [u64; 44] = &[
+    static BITSET_CANONICAL: [u64; 44] = [
         0b0000011111111111111111111111111000000000000000000000000000000000,
         0b0000000000111111111111111111111111111111111111111111111111111111,
         0b0101010101010101010101010101010101010101010101010101010000000001,
@@ -543,7 +543,7 @@ pub mod uppercase {
         0b1111011111111111000000000000000000000000000000000000000000000000,
         0b1111111100000000111111110000000000111111000000001111111100000000,
     ];
-    const BITSET_MAPPING: &'static [(u8, u8); 25] = &[
+    static BITSET_MAPPING: [(u8, u8); 25] = [
         (0, 187), (0, 177), (0, 171), (0, 167), (0, 164), (0, 32), (0, 47), (0, 51), (0, 121),
         (0, 117), (0, 109), (1, 150), (1, 148), (1, 142), (1, 134), (1, 131), (1, 64), (2, 164),
         (2, 146), (2, 20), (3, 146), (3, 140), (3, 134), (4, 178), (4, 171),
diff --git a/library/core/tests/ascii.rs b/library/core/tests/ascii.rs
index 3d3f8ac10c6..ce09ee507f1 100644
--- a/library/core/tests/ascii.rs
+++ b/library/core/tests/ascii.rs
@@ -481,9 +481,25 @@ fn ascii_ctype_const() {
 }
 
 #[test]
-fn test_ascii_display() {
-    assert_eq!(b"foo'bar".escape_ascii().to_string(), r#"foo\'bar"#);
-    assert_eq!(b"\0\xff".escape_ascii().to_string(), r#"\x00\xff"#);
+fn test_escape_ascii() {
+    let mut buf = [0u8; 0x1F + 7]; // 0..=0x1F plus two quotes, slash, \x7F, \x80, \xFF
+    for idx in 0..=0x1F {
+        buf[idx] = idx as u8;
+    }
+    buf[0x20] = b'\'';
+    buf[0x21] = b'"';
+    buf[0x22] = b'\\';
+    buf[0x23] = 0x7F;
+    buf[0x24] = 0x80;
+    buf[0x25] = 0xff;
+    assert_eq!(
+        buf.escape_ascii().to_string(),
+        r#"\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\'\"\\\x7f\x80\xff"#
+    );
+}
+
+#[test]
+fn test_escape_ascii_iter() {
     let mut it = b"\0fastpath\xffremainder\xff".escape_ascii();
     let _ = it.advance_by(4);
     let _ = it.advance_back_by(4);
diff --git a/library/core/tests/atomic.rs b/library/core/tests/atomic.rs
index 2bdaeb3845a..0ffba538b20 100644
--- a/library/core/tests/atomic.rs
+++ b/library/core/tests/atomic.rs
@@ -229,7 +229,7 @@ fn static_init() {
 
 #[test]
 // FIXME(static_mut_refs): Do not allow `static_mut_refs` lint
-#[cfg_attr(not(bootstrap), allow(static_mut_refs))]
+#[allow(static_mut_refs)]
 fn atomic_access_bool() {
     static mut ATOMIC: AtomicBool = AtomicBool::new(false);
 
diff --git a/library/core/tests/hash/mod.rs b/library/core/tests/hash/mod.rs
index 03826fc4c92..bf91e9e5df0 100644
--- a/library/core/tests/hash/mod.rs
+++ b/library/core/tests/hash/mod.rs
@@ -164,7 +164,7 @@ fn test_indirect_hasher() {
 }
 
 #[test]
-fn test_build_hasher_object_safe() {
+fn test_build_hasher_dyn_compatible() {
     use std::hash::{DefaultHasher, RandomState};
 
     let _: &dyn BuildHasher<Hasher = DefaultHasher> = &RandomState::new();
diff --git a/library/core/tests/lib.rs b/library/core/tests/lib.rs
index 196e91ee3e9..bfc0b638b7e 100644
--- a/library/core/tests/lib.rs
+++ b/library/core/tests/lib.rs
@@ -1,5 +1,4 @@
 // tidy-alphabetical-start
-#![cfg_attr(bootstrap, feature(const_mut_refs))]
 #![cfg_attr(target_has_atomic = "128", feature(integer_atomics))]
 #![cfg_attr(test, feature(cfg_match))]
 #![feature(alloc_layout_extra)]
@@ -16,33 +15,23 @@
 #![feature(clone_to_uninit)]
 #![feature(const_align_of_val_raw)]
 #![feature(const_align_offset)]
-#![feature(const_array_from_ref)]
 #![feature(const_black_box)]
 #![feature(const_hash)]
 #![feature(const_heap)]
-#![feature(const_ip)]
-#![feature(const_ipv4)]
-#![feature(const_ipv6)]
 #![feature(const_likely)]
 #![feature(const_nonnull_new)]
-#![feature(const_option)]
 #![feature(const_option_ext)]
 #![feature(const_pin)]
 #![feature(const_pointer_is_aligned)]
-#![feature(const_ptr_write)]
-#![feature(const_result)]
-#![feature(const_slice_from_ref)]
 #![feature(const_three_way_compare)]
 #![feature(const_trait_impl)]
 #![feature(core_intrinsics)]
 #![feature(core_io_borrowed_buf)]
 #![feature(core_private_bignum)]
 #![feature(core_private_diy_float)]
-#![feature(debug_more_non_exhaustive)]
 #![feature(dec2flt)]
 #![feature(duration_constants)]
 #![feature(duration_constructors)]
-#![feature(duration_consts_float)]
 #![feature(error_generic_member_access)]
 #![feature(exact_size_is_empty)]
 #![feature(extern_types)]
@@ -57,6 +46,7 @@
 #![feature(hashmap_internals)]
 #![feature(int_roundings)]
 #![feature(ip)]
+#![feature(ip_from)]
 #![feature(is_ascii_octdigit)]
 #![feature(isqrt)]
 #![feature(iter_advance_by)]
diff --git a/library/core/tests/net/ip_addr.rs b/library/core/tests/net/ip_addr.rs
index a10b51c550d..707f9a160e1 100644
--- a/library/core/tests/net/ip_addr.rs
+++ b/library/core/tests/net/ip_addr.rs
@@ -494,6 +494,7 @@ fn ipv6_properties() {
             let octets = &[$($octet),*];
             assert_eq!(&ip!($s).octets(), octets);
             assert_eq!(Ipv6Addr::from(*octets), ip!($s));
+            assert_eq!(Ipv6Addr::from_octets(*octets), ip!($s));
 
             let unspecified: u32 = 1 << 0;
             let loopback: u32 = 1 << 1;
@@ -846,15 +847,19 @@ fn ipv6_from_constructors() {
 
 #[test]
 fn ipv4_from_octets() {
-    assert_eq!(Ipv4Addr::from([127, 0, 0, 1]), Ipv4Addr::new(127, 0, 0, 1))
+    assert_eq!(Ipv4Addr::from([127, 0, 0, 1]), Ipv4Addr::new(127, 0, 0, 1));
+    assert_eq!(Ipv4Addr::from_octets([127, 0, 0, 1]), Ipv4Addr::new(127, 0, 0, 1));
 }
 
 #[test]
 fn ipv6_from_segments() {
     let from_u16s =
         Ipv6Addr::from([0x0011, 0x2233, 0x4455, 0x6677, 0x8899, 0xaabb, 0xccdd, 0xeeff]);
+    let from_u16s_explicit =
+        Ipv6Addr::from_segments([0x0011, 0x2233, 0x4455, 0x6677, 0x8899, 0xaabb, 0xccdd, 0xeeff]);
     let new = Ipv6Addr::new(0x0011, 0x2233, 0x4455, 0x6677, 0x8899, 0xaabb, 0xccdd, 0xeeff);
     assert_eq!(new, from_u16s);
+    assert_eq!(new, from_u16s_explicit);
 }
 
 #[test]
@@ -865,7 +870,15 @@ fn ipv6_from_octets() {
         0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee,
         0xff,
     ]);
+    let from_u16s_explicit =
+        Ipv6Addr::from_segments([0x0011, 0x2233, 0x4455, 0x6677, 0x8899, 0xaabb, 0xccdd, 0xeeff]);
+    let from_u8s_explicit = Ipv6Addr::from_octets([
+        0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee,
+        0xff,
+    ]);
     assert_eq!(from_u16s, from_u8s);
+    assert_eq!(from_u16s, from_u16s_explicit);
+    assert_eq!(from_u16s_explicit, from_u8s_explicit);
 }
 
 #[test]
@@ -915,6 +928,9 @@ fn ipv4_const() {
     const OCTETS: [u8; 4] = IP_ADDRESS.octets();
     assert_eq!(OCTETS, [127, 0, 0, 1]);
 
+    const FROM_OCTETS: Ipv4Addr = Ipv4Addr::from_octets(OCTETS);
+    assert_eq!(IP_ADDRESS, FROM_OCTETS);
+
     const IS_UNSPECIFIED: bool = IP_ADDRESS.is_unspecified();
     assert!(!IS_UNSPECIFIED);
 
@@ -971,9 +987,15 @@ fn ipv6_const() {
     const SEGMENTS: [u16; 8] = IP_ADDRESS.segments();
     assert_eq!(SEGMENTS, [0, 0, 0, 0, 0, 0, 0, 1]);
 
+    const FROM_SEGMENTS: Ipv6Addr = Ipv6Addr::from_segments(SEGMENTS);
+    assert_eq!(IP_ADDRESS, FROM_SEGMENTS);
+
     const OCTETS: [u8; 16] = IP_ADDRESS.octets();
     assert_eq!(OCTETS, [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1]);
 
+    const FROM_OCTETS: Ipv6Addr = Ipv6Addr::from_octets(OCTETS);
+    assert_eq!(IP_ADDRESS, FROM_OCTETS);
+
     const IS_UNSPECIFIED: bool = IP_ADDRESS.is_unspecified();
     assert!(!IS_UNSPECIFIED);
 
diff --git a/library/core/tests/slice.rs b/library/core/tests/slice.rs
index 7197f3812e5..9ae2bcc8526 100644
--- a/library/core/tests/slice.rs
+++ b/library/core/tests/slice.rs
@@ -1802,57 +1802,6 @@ fn brute_force_rotate_test_1() {
 
 #[test]
 #[cfg(not(target_arch = "wasm32"))]
-fn sort_unstable() {
-    use rand::Rng;
-
-    // Miri is too slow (but still need to `chain` to make the types match)
-    let lens = if cfg!(miri) { (2..20).chain(0..0) } else { (2..25).chain(500..510) };
-    let rounds = if cfg!(miri) { 1 } else { 100 };
-
-    let mut v = [0; 600];
-    let mut tmp = [0; 600];
-    let mut rng = crate::test_rng();
-
-    for len in lens {
-        let v = &mut v[0..len];
-        let tmp = &mut tmp[0..len];
-
-        for &modulus in &[5, 10, 100, 1000] {
-            for _ in 0..rounds {
-                for i in 0..len {
-                    v[i] = rng.gen::<i32>() % modulus;
-                }
-
-                // Sort in default order.
-                tmp.copy_from_slice(v);
-                tmp.sort_unstable();
-                assert!(tmp.windows(2).all(|w| w[0] <= w[1]));
-
-                // Sort in ascending order.
-                tmp.copy_from_slice(v);
-                tmp.sort_unstable_by(|a, b| a.cmp(b));
-                assert!(tmp.windows(2).all(|w| w[0] <= w[1]));
-
-                // Sort in descending order.
-                tmp.copy_from_slice(v);
-                tmp.sort_unstable_by(|a, b| b.cmp(a));
-                assert!(tmp.windows(2).all(|w| w[0] >= w[1]));
-            }
-        }
-    }
-
-    // Should not panic.
-    [0i32; 0].sort_unstable();
-    [(); 10].sort_unstable();
-    [(); 100].sort_unstable();
-
-    let mut v = [0xDEADBEEFu64];
-    v.sort_unstable();
-    assert!(v == [0xDEADBEEF]);
-}
-
-#[test]
-#[cfg(not(target_arch = "wasm32"))]
 #[cfg_attr(miri, ignore)] // Miri is too slow
 fn select_nth_unstable() {
     use core::cmp::Ordering::{Equal, Greater, Less};