Elements. Switch away from TypeAliasElement.aliasedElement

Change-Id: I2ddc4c1a850871d63c0b12f0a14293fff888d523
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/441440
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

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

@@ -709,7 +709,7 @@ class DeclarationHelper {
     TypeAliasElement alias,
     ImportData? importData,
   ) {
-    var aliasedElement = alias.aliasedElement;
+    var aliasedElement = alias.aliasedType.element;
     if (aliasedElement is ClassElement) {
       _suggestConstructors(
         aliasedElement.constructors,

pkg/analysis_server/lib/src/services/correction/dart/convert_to_function_declaration.dart

@@ -83,10 +83,10 @@ class ConvertToFunctionDeclaration extends ResolvedCorrectionProducer {
       DartType? returnType;
       List<FormalParameterElement?>? parameterList;
       if (type case NamedType(
-        element: TypeAliasElement(:GenericFunctionTypeElement aliasedElement),
+        element: TypeAliasElement(:FunctionType aliasedType),
       )) {
-        returnType = aliasedElement.returnType;
-        parameterList = aliasedElement.formalParameters;
+        returnType = aliasedType.returnType;
+        parameterList = aliasedType.formalParameters;
       } else if (type is GenericFunctionType) {
         returnType = type.returnType?.type;
         parameterList =

pkg/analyzer_plugin/lib/src/utilities/completion/suggestion_builder.dart

@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart'
     hide Element, ElementKind;
@@ -139,13 +140,10 @@ class SuggestionBuilderImpl implements SuggestionBuilder {
       var type = element.type;
       return type.getDisplayString();
     } else if (element is TypeAliasElement) {
-      var aliasedElement = element.aliasedElement;
-      if (aliasedElement is GenericFunctionTypeElement) {
-        var returnType = aliasedElement.returnType;
-        return returnType.getDisplayString();
-      } else {
-        return null;
+      if (element.aliasedType case FunctionType aliasedType) {
+        return aliasedType.returnType.getDisplayString();
       }
+      return null;
     } else {
       return null;
     }