Address some feedback on a previous CL

Change-Id: I2e0f59fb2d22677efa58720d0bd6e73ac65daa22
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/350980
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>

pkg/analysis_server/lib/src/services/completion/dart/declaration_helper.dart

@@ -364,30 +364,27 @@ class DeclarationHelper {
       case EnumElement():
         var augmented = element.augmented;
         _addStaticMembers(
-            accessors: [...element.accessors, ...?augmented?.accessors],
+            accessors: augmented?.accessors ?? element.accessors,
             constructors: const [],
             containingElement: element,
-            fields: [...element.fields, ...?augmented?.fields],
-            methods: [...element.methods, ...?augmented?.methods]);
+            fields: augmented?.fields ?? element.fields,
+            methods: augmented?.methods ?? element.methods);
       case ExtensionElement():
         var augmented = element.augmented;
         _addStaticMembers(
-            accessors: [...element.accessors, ...?augmented?.accessors],
+            accessors: augmented?.accessors ?? element.accessors,
             constructors: const [],
             containingElement: element,
-            fields: [...element.fields, ...?augmented?.fields],
-            methods: [...element.methods, ...?augmented?.methods]);
+            fields: augmented?.fields ?? element.fields,
+            methods: augmented?.methods ?? element.methods);
       case InterfaceElement():
         var augmented = element.augmented;
         _addStaticMembers(
-            accessors: [...element.accessors, ...?augmented?.accessors],
-            constructors: [
-              ...element.constructors,
-              ...?augmented?.constructors
-            ],
+            accessors: augmented?.accessors ?? element.accessors,
+            constructors: augmented?.constructors ?? element.constructors,
             containingElement: element,
-            fields: [...element.fields, ...?augmented?.fields],
-            methods: [...element.methods, ...?augmented?.methods]);
+            fields: augmented?.fields ?? element.fields,
+            methods: augmented?.methods ?? element.methods);
     }
   }
 
@@ -775,6 +772,8 @@ class DeclarationHelper {
 
   /// Adds suggestions for the [members] of the [containingElement].
   void _addMembers(Element containingElement, NodeList<ClassMember> members) {
+    // TODO(brianwilkerson): Replace this method with methods similar to
+    //  `_addMembersOfClass`.
     for (var member in members) {
       switch (member) {
         case ConstructorDeclaration():
@@ -832,7 +831,7 @@ class DeclarationHelper {
         var classElement = parent.declaredElement;
         if (classElement != null) {
           if (!mustBeType) {
-            _addMembers(classElement, parent.members);
+            _addMembersOfClass(classElement);
           }
           _suggestTypeParameters(classElement.typeParameters);
         }
@@ -890,6 +889,27 @@ class DeclarationHelper {
     }
   }
 
+  /// Adds suggestions for the [members] of the [containingElement].
+  void _addMembersOfClass(ClassElement classElement) {
+    // Add any immediate members from augmentations.
+    var augmented = classElement.augmented;
+    for (var accessor in augmented?.accessors ?? classElement.accessors) {
+      if (!accessor.isSynthetic && (!mustBeStatic || accessor.isStatic)) {
+        _suggestProperty(accessor, classElement);
+      }
+    }
+    for (var field in augmented?.fields ?? classElement.fields) {
+      if (!field.isSynthetic && (!mustBeStatic || field.isStatic)) {
+        _suggestField(field, classElement);
+      }
+    }
+    for (var method in augmented?.methods ?? classElement.methods) {
+      if (!mustBeStatic || method.isStatic) {
+        _suggestMethod(method, classElement);
+      }
+    }
+  }
+
   /// Adds suggestions for the instance members declared on `Object`.
   void _addMembersOfDartCoreObject() {
     _addInstanceMembers(

pkg/analysis_server/test/test_macros.dart

@@ -11,7 +11,13 @@
 mixin TestMacros {
   /// Return the declaration of a macro that will add a member to a library.
   ///
-  /// The text of the member is provided as an argument to the macro.
+  /// The text of the member to be declared is provided as an argument to the
+  /// macro that is returned. For example, the following can be used to generate
+  /// a top level function in the library containing the class `C`:
+  /// ```dart
+  /// @DeclareInLibrary('void generatedTopLevelFunction() {}')
+  /// class C {}
+  /// ```
   String declareInLibraryMacro() {
     return '''
 macro class DeclareInLibrary
@@ -41,7 +47,15 @@ macro class DeclareInLibrary
 
   /// Return the declaration of a macro that will add a member to a type.
   ///
-  /// The text of the member is provided as an argument to the macro.
+  /// The text of the member to be declared is provided as an argument to the
+  /// macro that is returned. For example, the following can be used to generate
+  /// a method in the class `C`:
+  /// ```dart
+  /// @DeclareInType('  void generatedMethod() {}')
+  /// class C {}
+  /// ```
+  /// (Adding the indent makes the content of the generated code look nicer, but
+  /// isn't required.)
   String declareInTypeMacro() {
     return '''
 macro class DeclareInType

pkg/analyzer/lib/dart/element/element.dart

@@ -1475,7 +1475,14 @@ abstract class InstanceElement
   @experimental
   InstanceElement? get augmentationTarget;
 
-  /// The result of applying augmentations.
+  /// The result of merging augmentations.
+  ///
+  /// Returns `null` if this element is an augmentation and there is no base
+  /// element from which a merge can be performed.
+  ///
+  /// If a non-null instance is returned it will include the members of
+  /// the base element and its augmentations as specified by the merge
+  /// operations.
   @experimental
   AugmentedInstanceElement? get augmented;