[Concurrency] Serialize @asyncHandler attribute.

DougGregor · DougGregor · commit 8cd892aba8ed · 2020-08-13T21:45:53.000-07:00
We'll be able to infer @asyncHandler attributes from protocol
requirements, which means we'll need to serialize this information.
diff --git a/include/swift/AST/Attr.def b/include/swift/AST/Attr.def
@@ -562,8 +562,8 @@ SIMPLE_DECL_ATTR(noDerivative, NoDerivative,
 
 SIMPLE_DECL_ATTR(asyncHandler, AsyncHandler,
   OnFunc | UserInaccessible |
-  ABIStableToAdd | ABIStableToRemove | APIStableToAdd | APIStableToRemove |
-  NotSerialized, 101)
+  ABIStableToAdd | ABIStableToRemove | APIStableToAdd | APIStableToRemove,
+  101)
 
 #undef TYPE_ATTR
 #undef DECL_ATTR_ALIAS
