diff --git a/library/alloc/src/boxed.rs b/library/alloc/src/boxed.rs
index e5f6b0c0c65..b154688fb08 100644
--- a/library/alloc/src/boxed.rs
+++ b/library/alloc/src/boxed.rs
@@ -2033,7 +2033,7 @@ extern "rust-call" fn call(&self, args: Args) -> Self::Output {
     }
 }
 
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<T: ?Sized + Unsize<U>, U: ?Sized, A: Allocator> CoerceUnsized<Box<U, A>> for Box<T, A> {}
 
 #[unstable(feature = "dispatch_from_dyn", issue = "none")]
diff --git a/library/alloc/src/rc.rs b/library/alloc/src/rc.rs
index 38e31b1802a..80a5913daa6 100644
--- a/library/alloc/src/rc.rs
+++ b/library/alloc/src/rc.rs
@@ -336,7 +336,7 @@ impl<T: RefUnwindSafe + ?Sized> UnwindSafe for Rc<T> {}
 #[stable(feature = "rc_ref_unwind_safe", since = "1.58.0")]
 impl<T: RefUnwindSafe + ?Sized> RefUnwindSafe for Rc<T> {}
 
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Rc<U>> for Rc<T> {}
 
 #[unstable(feature = "dispatch_from_dyn", issue = "none")]
@@ -2190,7 +2190,7 @@ impl<T: ?Sized> !marker::Send for Weak<T> {}
 #[stable(feature = "rc_weak", since = "1.4.0")]
 impl<T: ?Sized> !marker::Sync for Weak<T> {}
 
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Weak<U>> for Weak<T> {}
 
 #[unstable(feature = "dispatch_from_dyn", issue = "none")]
diff --git a/library/alloc/src/sync.rs b/library/alloc/src/sync.rs
index f7dc4d1094c..ddcd863aa3e 100644
--- a/library/alloc/src/sync.rs
+++ b/library/alloc/src/sync.rs
@@ -254,7 +254,7 @@ unsafe impl<T: ?Sized + Sync + Send> Sync for Arc<T> {}
 #[stable(feature = "catch_unwind", since = "1.9.0")]
 impl<T: RefUnwindSafe + ?Sized> UnwindSafe for Arc<T> {}
 
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Arc<U>> for Arc<T> {}
 
 #[unstable(feature = "dispatch_from_dyn", issue = "none")]
@@ -306,7 +306,7 @@ unsafe impl<T: ?Sized + Sync + Send> Send for Weak<T> {}
 #[stable(feature = "arc_weak", since = "1.4.0")]
 unsafe impl<T: ?Sized + Sync + Send> Sync for Weak<T> {}
 
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Weak<U>> for Weak<T> {}
 #[unstable(feature = "dispatch_from_dyn", issue = "none")]
 impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<Weak<U>> for Weak<T> {}
diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs
index 47cce2aa39b..b4e173ce03d 100644
--- a/library/core/src/cell.rs
+++ b/library/core/src/cell.rs
@@ -568,7 +568,7 @@ pub fn take(&self) -> T {
     }
 }
 
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<T: CoerceUnsized<U>, U> CoerceUnsized<Cell<U>> for Cell<T> {}
 
 impl<T> Cell<[T]> {
@@ -1266,7 +1266,7 @@ fn from(t: T) -> RefCell<T> {
     }
 }
 
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<T: CoerceUnsized<U>, U> CoerceUnsized<RefCell<U>> for RefCell<T> {}
 
 struct BorrowRef<'b> {
@@ -1492,7 +1492,7 @@ pub fn leak(orig: Ref<'b, T>) -> &'b T {
     }
 }
 
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<'b, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Ref<'b, U>> for Ref<'b, T> {}
 
 #[stable(feature = "std_guard_impls", since = "1.20.0")]
@@ -1738,7 +1738,7 @@ fn deref_mut(&mut self) -> &mut T {
     }
 }
 
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<'b, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<RefMut<'b, U>> for RefMut<'b, T> {}
 
 #[stable(feature = "std_guard_impls", since = "1.20.0")]
@@ -2074,7 +2074,7 @@ fn from(t: T) -> UnsafeCell<T> {
     }
 }
 
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<T: CoerceUnsized<U>, U> CoerceUnsized<UnsafeCell<U>> for UnsafeCell<T> {}
 
 /// [`UnsafeCell`], but [`Sync`].
@@ -2164,7 +2164,7 @@ fn from(t: T) -> SyncUnsafeCell<T> {
     }
 }
 
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 //#[unstable(feature = "sync_unsafe_cell", issue = "95439")]
 impl<T: CoerceUnsized<U>, U> CoerceUnsized<SyncUnsafeCell<U>> for SyncUnsafeCell<T> {}
 
diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs
index 42c34280197..4b85c1112b9 100644
--- a/library/core/src/marker.rs
+++ b/library/core/src/marker.rs
@@ -126,7 +126,7 @@ 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
-#[unstable(feature = "unsize", issue = "27732")]
+#[unstable(feature = "unsize", issue = "18598")]
 #[lang = "unsize"]
 #[cfg_attr(not(bootstrap), rustc_deny_explicit_impl)]
 pub trait Unsize<T: ?Sized> {
diff --git a/library/core/src/ops/mod.rs b/library/core/src/ops/mod.rs
index eb2a92f4644..97d9b750d92 100644
--- a/library/core/src/ops/mod.rs
+++ b/library/core/src/ops/mod.rs
@@ -201,7 +201,7 @@
 #[unstable(feature = "generator_trait", issue = "43122")]
 pub use self::generator::{Generator, GeneratorState};
 
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 pub use self::unsize::CoerceUnsized;
 
 #[unstable(feature = "dispatch_from_dyn", issue = "none")]
diff --git a/library/core/src/ops/unsize.rs b/library/core/src/ops/unsize.rs
index a920b9165c1..b51f12580ea 100644
--- a/library/core/src/ops/unsize.rs
+++ b/library/core/src/ops/unsize.rs
@@ -31,41 +31,41 @@
 /// [dst-coerce]: https://github.com/rust-lang/rfcs/blob/master/text/0982-dst-coercion.md
 /// [unsize]: crate::marker::Unsize
 /// [nomicon-coerce]: ../../nomicon/coercions.html
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 #[lang = "coerce_unsized"]
 pub trait CoerceUnsized<T: ?Sized> {
     // Empty.
 }
 
 // &mut T -> &mut U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a mut U> for &'a mut T {}
 // &mut T -> &U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<'a, 'b: 'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a U> for &'b mut T {}
 // &mut T -> *mut U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*mut U> for &'a mut T {}
 // &mut T -> *const U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for &'a mut T {}
 
 // &T -> &U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<'a, 'b: 'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a U> for &'b T {}
 // &T -> *const U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for &'a T {}
 
 // *mut T -> *mut U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*mut U> for *mut T {}
 // *mut T -> *const U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *mut T {}
 
 // *const T -> *const U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[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
diff --git a/library/core/src/ptr/non_null.rs b/library/core/src/ptr/non_null.rs
index c4348169c78..af79d4bbd83 100644
--- a/library/core/src/ptr/non_null.rs
+++ b/library/core/src/ptr/non_null.rs
@@ -712,7 +712,7 @@ fn clone(&self) -> Self {
 #[stable(feature = "nonnull", since = "1.25.0")]
 impl<T: ?Sized> Copy for NonNull<T> {}
 
-#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[unstable(feature = "coerce_unsized", issue = "18598")]
 impl<T: ?Sized, U: ?Sized> CoerceUnsized<NonNull<U>> for NonNull<T> where T: Unsize<U> {}
 
 #[unstable(feature = "dispatch_from_dyn", issue = "none")]