add rustc_diagnostic_item for Cell & SyncUnsafeCell

Author: GrigorenkoPV

compiler/rustc_span/src/symbol.rs

@@ -170,6 +170,7 @@ symbols! {
         CallOnceFuture,
         CallRefFuture,
         Capture,
+        Cell,
         Center,
         Cleanup,
         Clone,
@@ -321,6 +322,7 @@ symbols! {
         SubdiagMessage,
         Subdiagnostic,
         Sync,
+        SyncUnsafeCell,
         T,
         Target,
         ToOwned,

library/core/src/cell.rs

@@ -304,6 +304,7 @@ pub use once::OnceCell;
 /// ```
 ///
 /// See the [module-level documentation](self) for more.
+#[cfg_attr(not(test), rustc_diagnostic_item = "Cell")]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[repr(transparent)]
 pub struct Cell<T: ?Sized> {
@@ -2295,6 +2296,7 @@ impl<T> UnsafeCell<*mut T> {
 /// making this type just as unsafe to use.
 ///
 /// See [`UnsafeCell`] for details.
+#[cfg_attr(not(test), rustc_diagnostic_item = "SyncUnsafeCell")]
 #[unstable(feature = "sync_unsafe_cell", issue = "95439")]
 #[repr(transparent)]
 pub struct SyncUnsafeCell<T: ?Sized> {