dotnet-core/release-notes/3.0/preview/api-diff/preview2/3.0-preview2_System.Runtime.CompilerServices.md

# System.Runtime.CompilerServices

``` diff
 namespace System.Runtime.CompilerServices {
+    public sealed class AsyncIteratorStateMachineAttribute : StateMachineAttribute {
+        public AsyncIteratorStateMachineAttribute(Type stateMachineType);
+    }
-    public readonly struct ConfiguredAsyncEnumerable<T> {
 {
-        public ConfiguredAsyncEnumerable<T>.Enumerator GetAsyncEnumerator();

-        public readonly struct Enumerator {
 {
-            public T Current { get; }

-            public ConfiguredValueTaskAwaitable DisposeAsync();

-            public ConfiguredValueTaskAwaitable<bool> MoveNextAsync();

-        }
-    }
+    public readonly struct ConfiguredCancelableAsyncEnumerable<T> {
+        public ConfiguredCancelableAsyncEnumerable<T> ConfigureAwait(bool continueOnCapturedContext);
+        public ConfiguredCancelableAsyncEnumerable<T>.Enumerator GetAsyncEnumerator();
+        public ConfiguredCancelableAsyncEnumerable<T> WithCancellation(CancellationToken cancellationToken);
+        public readonly struct Enumerator {
+            public T Current { get; }
+            public ConfiguredValueTaskAwaitable DisposeAsync();
+            public ConfiguredValueTaskAwaitable<bool> MoveNextAsync();
+        }
+    }
     public static class RuntimeFeature {
+        public static bool IsDynamicCodeCompiled { get; }
+        public static bool IsDynamicCodeSupported { get; }
     }
 }
```