diff --git a/library/core/src/mem/maybe_uninit.rs b/library/core/src/mem/maybe_uninit.rs
index 3507d1a0a9a8..aee28c4590c2 100644
--- a/library/core/src/mem/maybe_uninit.rs
+++ b/library/core/src/mem/maybe_uninit.rs
@@ -1128,7 +1128,6 @@ impl<T> [MaybeUninit<T>] {
     /// # Examples
     ///
     /// ```
-    /// #![feature(maybe_uninit_write_slice)]
     /// use std::mem::MaybeUninit;
     ///
     /// let mut dst = [MaybeUninit::uninit(); 32];
@@ -1140,8 +1139,6 @@ impl<T> [MaybeUninit<T>] {
     /// ```
     ///
     /// ```
-    /// #![feature(maybe_uninit_write_slice)]
-    ///
     /// let mut vec = Vec::with_capacity(32);
     /// let src = [0; 16];
     ///
@@ -1157,7 +1154,8 @@ impl<T> [MaybeUninit<T>] {
     /// ```
     ///
     /// [`write_clone_of_slice`]: slice::write_clone_of_slice
-    #[unstable(feature = "maybe_uninit_write_slice", issue = "79995")]
+    #[stable(feature = "maybe_uninit_write_slice", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "maybe_uninit_write_slice", since = "CURRENT_RUSTC_VERSION")]
     pub const fn write_copy_of_slice(&mut self, src: &[T]) -> &mut [T]
     where
         T: Copy,
@@ -1188,7 +1186,6 @@ impl<T> [MaybeUninit<T>] {
     /// # Examples
     ///
     /// ```
-    /// #![feature(maybe_uninit_write_slice)]
     /// use std::mem::MaybeUninit;
     ///
     /// let mut dst = [const { MaybeUninit::uninit() }; 5];
@@ -1203,8 +1200,6 @@ impl<T> [MaybeUninit<T>] {
     /// ```
     ///
     /// ```
-    /// #![feature(maybe_uninit_write_slice)]
-    ///
     /// let mut vec = Vec::with_capacity(32);
     /// let src = ["rust", "is", "a", "pretty", "cool", "language"].map(|s| s.to_string());
     ///
@@ -1220,7 +1215,7 @@ impl<T> [MaybeUninit<T>] {
     /// ```
     ///
     /// [`write_copy_of_slice`]: slice::write_copy_of_slice
-    #[unstable(feature = "maybe_uninit_write_slice", issue = "79995")]
+    #[stable(feature = "maybe_uninit_write_slice", since = "CURRENT_RUSTC_VERSION")]
     pub fn write_clone_of_slice(&mut self, src: &[T]) -> &mut [T]
     where
         T: Clone,
@@ -1415,7 +1410,7 @@ impl<T> [MaybeUninit<T>] {
     /// # Examples
     ///
     /// ```
-    /// #![feature(maybe_uninit_as_bytes, maybe_uninit_write_slice, maybe_uninit_slice)]
+    /// #![feature(maybe_uninit_as_bytes, maybe_uninit_slice)]
     /// use std::mem::MaybeUninit;
     ///
     /// let uninit = [MaybeUninit::new(0x1234u16), MaybeUninit::new(0x5678u16)];
@@ -1442,7 +1437,7 @@ impl<T> [MaybeUninit<T>] {
     /// # Examples
     ///
     /// ```
-    /// #![feature(maybe_uninit_as_bytes, maybe_uninit_write_slice, maybe_uninit_slice)]
+    /// #![feature(maybe_uninit_as_bytes, maybe_uninit_slice)]
     /// use std::mem::MaybeUninit;
     ///
     /// let mut uninit = [MaybeUninit::<u16>::uninit(), MaybeUninit::<u16>::uninit()];
diff --git a/library/coretests/tests/lib.rs b/library/coretests/tests/lib.rs
index e190536abcf9..ac61dc96dc9c 100644
--- a/library/coretests/tests/lib.rs
+++ b/library/coretests/tests/lib.rs
@@ -81,7 +81,6 @@
 #![feature(lazy_get)]
 #![feature(maybe_uninit_fill)]
 #![feature(maybe_uninit_uninit_array_transpose)]
-#![feature(maybe_uninit_write_slice)]
 #![feature(min_specialization)]
 #![feature(never_type)]
 #![feature(new_range_api)]
diff --git a/library/proc_macro/Cargo.toml b/library/proc_macro/Cargo.toml
index 0042a6e8ece5..3a4840a57334 100644
--- a/library/proc_macro/Cargo.toml
+++ b/library/proc_macro/Cargo.toml
@@ -14,3 +14,6 @@ rustc-literal-escaper = { version = "0.0.5", features = ["rustc-dep-of-std"] }
 [features]
 default = ["rustc-dep-of-std"]
 rustc-dep-of-std = []
+
+[lints.rust]
+unexpected_cfgs = { level = "warn", check-cfg = ['cfg(bootstrap)'] }
diff --git a/library/proc_macro/src/lib.rs b/library/proc_macro/src/lib.rs
index 4efdfcad924b..108ef7bce81a 100644
--- a/library/proc_macro/src/lib.rs
+++ b/library/proc_macro/src/lib.rs
@@ -22,7 +22,7 @@
 #![feature(staged_api)]
 #![feature(allow_internal_unstable)]
 #![feature(decl_macro)]
-#![feature(maybe_uninit_write_slice)]
+#![cfg_attr(bootstrap, feature(maybe_uninit_write_slice))]
 #![feature(negative_impls)]
 #![feature(panic_can_unwind)]
 #![feature(restricted_std)]
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 32f166e112e9..8df87124245b 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -349,7 +349,6 @@
 #![feature(lazy_get)]
 #![feature(maybe_uninit_array_assume_init)]
 #![feature(maybe_uninit_slice)]
-#![feature(maybe_uninit_write_slice)]
 #![feature(panic_can_unwind)]
 #![feature(panic_internals)]
 #![feature(pin_coerce_unsized_trait)]