Serialize and process patch metadata

pkg/compiler/lib/src/serialization/element_serialization.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.serialization.elements;
 
 import '../common.dart';
 import '../constants/constructors.dart';
 import '../constants/expressions.dart';
 import '../dart_types.dart';
@@ skipping 104 matching lines @@
       }
       int length = position.end - position.begin;
       if (element.name.length != length) {
         encoder.setInt(Key.LENGTH, length);
       }
     }
   }
 
   /// Serialize the metadata of [element] into [encoder].
   static void serializeMetadata(Element element, ObjectEncoder encoder) {
+    ListEncoder list;
+
+    void encodeAnnotation(MetadataAnnotation metadata) {
+      ObjectEncoder object = list.createObject();
+      object.setElement(Key.ELEMENT, metadata.annotatedElement);
+      SourceSpan sourcePosition = metadata.sourcePosition;
+      // TODO(johnniwinther): What is the base URI here?
+      object.setUri(Key.URI, sourcePosition.uri, sourcePosition.uri);
+      object.setInt(Key.OFFSET, sourcePosition.begin);
+      object.setInt(Key.LENGTH, sourcePosition.end - sourcePosition.begin);
+      object.setConstant(Key.CONSTANT, metadata.constant);
+    }
+
     if (element.metadata.isNotEmpty) {
-      ListEncoder list = encoder.createList(Key.METADATA);
-      for (MetadataAnnotation metadata in element.metadata) {
-        ObjectEncoder object = list.createObject();
-        object.setElement(Key.ELEMENT, metadata.annotatedElement);
-        SourceSpan sourcePosition = metadata.sourcePosition;
-        // TODO(johnniwinther): What is the base URI here?
-        object.setUri(Key.URI, sourcePosition.uri, sourcePosition.uri);
-        object.setInt(Key.OFFSET, sourcePosition.begin);
-        object.setInt(Key.LENGTH, sourcePosition.end - sourcePosition.begin);
-        object.setConstant(Key.CONSTANT, metadata.constant);
-      }
+      list = encoder.createList(Key.METADATA);
+      element.metadata.forEach(encodeAnnotation);
+    }
+    if (element.isPatched && element.implementation.metadata.isNotEmpty) {
+      list ??= encoder.createList(Key.METADATA);
+      element.implementation.metadata.forEach(encodeAnnotation);
     }
   }
 
   /// Serialize the parent relation for [element] into [encoder], i.e library,
   /// enclosing class, and compilation unit references.
   static void serializeParentRelation(Element element, ObjectEncoder encoder) {
     if (element.enclosingClass != null) {
       encoder.setElement(Key.CLASS, element.enclosingClass);
       if (element.enclosingClass.declaration.compilationUnit !=
           element.compilationUnit) {
@@ skipping 617 matching lines @@
         return new LocalVariableElementZ(decoder);
       case SerializedElementKind.EXTERNAL_LIBRARY:
       case SerializedElementKind.EXTERNAL_LIBRARY_MEMBER:
       case SerializedElementKind.EXTERNAL_CLASS_MEMBER:
       case SerializedElementKind.EXTERNAL_CONSTRUCTOR:
         break;
     }
     throw new UnsupportedError("Unexpected element kind '${elementKind}.");
   }
 }