7 files changed, 25 insertions, 9 deletions
diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs
index 9c578dcdc2a..59a6aa70620 100644
--- a/library/core/src/cell.rs
+++ b/library/core/src/cell.rs
@@ -698,14 +698,14 @@ impl<T, const N: usize> Cell<[T; N]> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(as_array_of_cells)]
     /// use std::cell::Cell;
     ///
     /// let mut array: [i32; 3] = [1, 2, 3];
     /// let cell_array: &Cell<[i32; 3]> = Cell::from_mut(&mut array);
     /// let array_cell: &[Cell<i32>; 3] = cell_array.as_array_of_cells();
     /// ```
-    #[unstable(feature = "as_array_of_cells", issue = "88248")]
+    #[stable(feature = "as_array_of_cells", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "as_array_of_cells", since = "CURRENT_RUSTC_VERSION")]
     pub const fn as_array_of_cells(&self) -> &[Cell<T>; N] {
         // SAFETY: `Cell<T>` has the same memory layout as `T`.
         unsafe { &*(self as *const Cell<[T; N]> as *const [Cell<T>; N]) }
diff --git a/library/core/src/iter/adapters/chain.rs b/library/core/src/iter/adapters/chain.rs
index dad3d79acb1..943b88e2330 100644
--- a/library/core/src/iter/adapters/chain.rs
+++ b/library/core/src/iter/adapters/chain.rs
@@ -45,8 +45,6 @@ impl<A, B> Chain<A, B> {
 /// # Examples
 ///
 /// ```
-/// #![feature(iter_chain)]
-///
 /// use std::iter::chain;
 ///
 /// let a = [1, 2, 3];
@@ -62,7 +60,7 @@ impl<A, B> Chain<A, B> {
 /// assert_eq!(iter.next(), Some(6));
 /// assert_eq!(iter.next(), None);
 /// ```
-#[unstable(feature = "iter_chain", reason = "recently added", issue = "125964")]
+#[stable(feature = "iter_chain", since = "CURRENT_RUSTC_VERSION")]
 pub fn chain<A, B>(a: A, b: B) -> Chain<A::IntoIter, B::IntoIter>
 where
     A: IntoIterator,
diff --git a/library/core/src/iter/adapters/mod.rs b/library/core/src/iter/adapters/mod.rs
index 2a0ef0189d1..6c6de0a4e5c 100644
--- a/library/core/src/iter/adapters/mod.rs
+++ b/library/core/src/iter/adapters/mod.rs
@@ -32,7 +32,7 @@ mod zip;
 pub use self::array_chunks::ArrayChunks;
 #[unstable(feature = "std_internals", issue = "none")]
 pub use self::by_ref_sized::ByRefSized;
-#[unstable(feature = "iter_chain", reason = "recently added", issue = "125964")]
+#[stable(feature = "iter_chain", since = "CURRENT_RUSTC_VERSION")]
 pub use self::chain::chain;
 #[stable(feature = "iter_cloned", since = "1.1.0")]
 pub use self::cloned::Cloned;
diff --git a/library/core/src/iter/mod.rs b/library/core/src/iter/mod.rs
index 56ca1305b60..bc07324f520 100644
--- a/library/core/src/iter/mod.rs
+++ b/library/core/src/iter/mod.rs
@@ -404,7 +404,7 @@ pub use self::adapters::StepBy;
 pub use self::adapters::TrustedRandomAccess;
 #[unstable(feature = "trusted_random_access", issue = "none")]
 pub use self::adapters::TrustedRandomAccessNoCoerce;
-#[unstable(feature = "iter_chain", reason = "recently added", issue = "125964")]
+#[stable(feature = "iter_chain", since = "CURRENT_RUSTC_VERSION")]
 pub use self::adapters::chain;
 pub(crate) use self::adapters::try_process;
 #[stable(feature = "iter_zip", since = "1.59.0")]
diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs
index bb91d057454..ccf41dfb01d 100644
--- a/library/core/src/macros/mod.rs
+++ b/library/core/src/macros/mod.rs
@@ -1770,4 +1770,15 @@ pub(crate) mod builtin {
     pub macro deref($pat:pat) {
         builtin # deref($pat)
     }
+
+    /// Derive macro generating an impl of the trait `From`.
+    /// Currently, it can only be used on single-field structs.
+    // Note that the macro is in a different module than the `From` trait,
+    // to avoid triggering an unstable feature being used if someone imports
+    // `std::convert::From`.
+    #[rustc_builtin_macro]
+    #[unstable(feature = "derive_from", issue = "144889")]
+    pub macro From($item: item) {
+        /* compiler built-in */
+    }
 }
diff --git a/library/core/src/prelude/v1.rs b/library/core/src/prelude/v1.rs
index a4be66b90ca..d8d82afb0e6 100644
--- a/library/core/src/prelude/v1.rs
+++ b/library/core/src/prelude/v1.rs
@@ -117,3 +117,10 @@ pub use crate::macros::builtin::deref;
     reason = "`type_alias_impl_trait` has open design concerns"
 )]
 pub use crate::macros::builtin::define_opaque;
+
+#[unstable(
+    feature = "derive_from",
+    issue = "144889",
+    reason = "`derive(From)` is unstable"
+)]
+pub use crate::macros::builtin::From;
diff --git a/library/core/src/ptr/mod.rs b/library/core/src/ptr/mod.rs
index b2607e45324..be26e714e67 100644
--- a/library/core/src/ptr/mod.rs
+++ b/library/core/src/ptr/mod.rs
@@ -974,7 +974,7 @@ pub const fn dangling_mut<T>() -> *mut T {
 #[must_use]
 #[inline(always)]
 #[stable(feature = "exposed_provenance", since = "1.84.0")]
-#[rustc_const_unstable(feature = "const_exposed_provenance", issue = "144538")]
+#[rustc_const_stable(feature = "const_exposed_provenance", since = "CURRENT_RUSTC_VERSION")]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 #[allow(fuzzy_provenance_casts)] // this *is* the explicit provenance API one should use instead
 pub const fn with_exposed_provenance<T>(addr: usize) -> *const T {
@@ -1015,7 +1015,7 @@ pub const fn with_exposed_provenance<T>(addr: usize) -> *const T {
 #[must_use]
 #[inline(always)]
 #[stable(feature = "exposed_provenance", since = "1.84.0")]
-#[rustc_const_unstable(feature = "const_exposed_provenance", issue = "144538")]
+#[rustc_const_stable(feature = "const_exposed_provenance", since = "CURRENT_RUSTC_VERSION")]
 #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
 #[allow(fuzzy_provenance_casts)] // this *is* the explicit provenance API one should use instead
 pub const fn with_exposed_provenance_mut<T>(addr: usize) -> *mut T {