Stabilize unreachable_unchecked as const fn

Author: jhpratt

core/src/hint.rs

@@ -44,7 +44,7 @@ use crate::intrinsics;
 /// ```
 #[inline]
 #[stable(feature = "unreachable", since = "1.27.0")]
-#[rustc_const_unstable(feature = "const_unreachable_unchecked", issue = "53188")]
+#[rustc_const_stable(feature = "const_unreachable_unchecked", since = "1.57.0")]
 pub const unsafe fn unreachable_unchecked() -> ! {
     // SAFETY: the safety contract for `intrinsics::unreachable` must
     // be upheld by the caller.

core/src/intrinsics.rs

@@ -735,7 +735,7 @@ extern "rust-intrinsic" {
     /// reach code marked with this function.
     ///
     /// The stabilized version of this intrinsic is [`core::hint::unreachable_unchecked`].
-    #[rustc_const_unstable(feature = "const_unreachable_unchecked", issue = "53188")]
+    #[rustc_const_stable(feature = "const_unreachable_unchecked", since = "1.57.0")]
     pub fn unreachable() -> !;
 
     /// Informs the optimizer that a condition is always true.

core/src/lib.rs

@@ -103,7 +103,6 @@
 #![feature(const_trait_impl)]
 #![feature(const_type_id)]
 #![feature(const_type_name)]
-#![feature(const_unreachable_unchecked)]
 #![feature(const_default_impls)]
 #![feature(duration_consts_2)]
 #![feature(ptr_metadata)]