CQ. Use public types as inputs, cast inside on entry.

Refactor `applicable_extensions.dart` so its public entry points accept
`DartType` and `ExtensionElement`, and perform implementation casts
internally at the analyzer boundary.

Remove the `strictCasts` parameter as well. Extension applicability
always ignores casts, so the parameter only added noise to the API and
to every call site.

Update completion and fix code in analysis_server to pass public types
directly and drop imports of internal analyzer type classes. Also
centralize the cast from `ExtensionElement` to `ExtensionElementImpl`
inside the helper instead of repeating it in multiple loops.

This makes the API cleaner, keeps the public/internal split in one
place, and reduces accidental coupling to analyzer implementation types.

Change-Id: I770ee5d8788f4c4a7004a0ad18a00cc52552e3b5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/494802
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Paul Berry <paulberry@google.com>
Reviewed-by: Samuel Rawlins <srawlins@google.com>

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

@@ -549,12 +549,9 @@ class DeclarationHelper {
         .applicableTo(
           targetLibrary: libraryElement,
           // Ignore nullability, consistent with non-extension members.
-          targetType:
-              (type.isDartCoreNull
-                      ? type
-                      : library.typeSystem.promoteToNonNull(type))
-                  as TypeImpl,
-          strictCasts: false,
+          targetType: type.isDartCoreNull
+              ? type
+              : library.typeSystem.promoteToNonNull(type),
         );
     var importData = ImportData(
       libraryUri: library.uri,
@@ -835,12 +832,9 @@ class DeclarationHelper {
     var applicableExtensions = accessibleExtensions.applicableTo(
       targetLibrary: libraryElement,
       // Ignore nullability, consistent with non-extension members.
-      targetType:
-          (type.isDartCoreNull
-                  ? type
-                  : libraryElement.typeSystem.promoteToNonNull(type))
-              as TypeImpl,
-      strictCasts: false,
+      targetType: type.isDartCoreNull
+          ? type
+          : libraryElement.typeSystem.promoteToNonNull(type),
     );
     for (var instantiatedExtension in applicableExtensions) {
       var extension = instantiatedExtension.extension;

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

@@ -7,7 +7,6 @@ import 'package:analysis_server_plugin/edit/dart/correction_producer.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
-import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/dart/resolver/applicable_extensions.dart';
 import 'package:analyzer/src/utilities/extensions/ast.dart';
 import 'package:analyzer_plugin/utilities/change_builder/change_builder_core.dart';
@@ -45,10 +44,7 @@ class AddExtensionOverride extends MultiCorrectionProducer {
     var nodeName = Name(libraryElement.uri, node.name);
     var extensions = libraryFragment.accessibleExtensions
         .havingMemberWithBaseName(nodeName)
-        .applicableTo(
-          targetLibrary: libraryElement,
-          targetType: targetType as TypeImpl,
-        );
+        .applicableTo(targetLibrary: libraryElement, targetType: targetType);
     var producers = <ResolvedCorrectionProducer>[];
     for (var extension in extensions) {
       var name = extension.extension.name;

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

@@ -730,8 +730,7 @@ abstract class _CreateExtensionMember extends ResolvedCorrectionProducer {
     }
     var instantiated = [extension].applicableTo(
       targetLibrary: libraryElement2,
-      targetType: extension.thisType as TypeImpl,
-      strictCasts: true,
+      targetType: extension.thisType,
     );
     if (instantiated.isNotEmpty) {
       return (unit.path, existingExtension);

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

@@ -19,7 +19,6 @@ import 'package:analyzer/diagnostic/diagnostic.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/source/source_range.dart';
 import 'package:analyzer/src/dart/ast/extensions.dart';
-import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/dart/resolver/applicable_extensions.dart';
 import 'package:analyzer/utilities/extensions/element.dart';
 import 'package:analyzer/utilities/extensions/uri.dart';
@@ -393,10 +392,7 @@ class ImportLibrary extends MultiCorrectionProducer {
       foundImport = true;
       extensionsInLibrary[import] = importedLibrary.exportedExtensions
           .havingMemberWithBaseName(memberName)
-          .applicableTo(
-            targetLibrary: libraryElement2,
-            targetType: targetType as TypeImpl,
-          );
+          .applicableTo(targetLibrary: libraryElement2, targetType: targetType);
     }
 
     // If the library at the URI is not already imported, we return a correction
@@ -405,10 +401,7 @@ class ImportLibrary extends MultiCorrectionProducer {
     if (!foundImport) {
       extensionsInLibrary[null] = libraryToImport.exportedExtensions
           .havingMemberWithBaseName(memberName)
-          .applicableTo(
-            targetLibrary: libraryElement2,
-            targetType: targetType as TypeImpl,
-          );
+          .applicableTo(targetLibrary: libraryElement2, targetType: targetType);
     }
     for (var entry in extensionsInLibrary.entries) {
       var extensionsInLibrary = entry.value;

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

@@ -8,7 +8,6 @@ import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
-import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/dart/resolver/applicable_extensions.dart';
 import 'package:analyzer/utilities/extensions/element.dart';
 import 'package:analyzer_plugin/utilities/change_builder/change_builder_core.dart';
@@ -110,7 +109,7 @@ class _UseDifferentDivisionOperator extends ResolvedCorrectionProducer {
               .havingMemberWithBaseName(name)
               .applicableTo(
                 targetLibrary: libraryElement2,
-                targetType: leftType! as TypeImpl,
+                targetType: leftType!,
               )
               .isNotEmpty;
         }).isEmpty;

pkg/analyzer/lib/src/dart/resolver/applicable_extensions.dart

@@ -80,8 +80,8 @@ abstract class _NotInstantiatedExtension<R> {
 
 class _NotInstantiatedExtensionWithMember
     extends _NotInstantiatedExtension<InstantiatedExtensionWithMember> {
-  final ExecutableElement? getter;
-  final ExecutableElement? setter;
+  final InternalExecutableElement? getter;
+  final InternalExecutableElement? setter;
 
   _NotInstantiatedExtensionWithMember(
     super.extension, {
@@ -120,17 +120,12 @@ extension ExtensionsExtensions on Iterable<ExtensionElement> {
   /// Extensions that can be applied, within [targetLibrary], to [targetType].
   List<InstantiatedExtensionWithoutMember> applicableTo({
     required LibraryElement targetLibrary,
-    required TypeImpl targetType,
-    required bool strictCasts,
+    required DartType targetType,
   }) {
     targetLibrary as LibraryElementImpl;
-    return map(
-      (e) => _NotInstantiatedExtensionWithoutMember(
-        // TODO(paulberry): eliminate this cast by changing the extension to
-        // apply only to `Iterable<ExtensionElementImpl>`.
-        e as ExtensionElementImpl,
-      ),
-    ).applicableTo(targetLibrary: targetLibrary, targetType: targetType);
+    return cast<ExtensionElementImpl>()
+        .map((e) => _NotInstantiatedExtensionWithoutMember(e))
+        .applicableTo(targetLibrary: targetLibrary, targetType: targetType);
   }
 
   /// Returns the sublist of [ExtensionElement]s that have an instance member
@@ -139,7 +134,7 @@ extension ExtensionsExtensions on Iterable<ExtensionElement> {
     Name baseName,
   ) {
     var result = <_NotInstantiatedExtensionWithMember>[];
-    for (var extension in this) {
+    for (var extension in cast<ExtensionElementImpl>()) {
       if (!baseName.isAccessibleFor(extension.library.uri)) {
         continue;
       }
@@ -150,9 +145,7 @@ extension ExtensionsExtensions on Iterable<ExtensionElement> {
         if (getter != null || setter != null) {
           result.add(
             _NotInstantiatedExtensionWithMember(
-              // TODO(paulberry): eliminate this cast by changing the extension
-              // to apply only to `Iterable<ExtensionElementImpl>`.
-              extension as ExtensionElementImpl,
+              extension,
               getter: getter,
               setter: setter,
             ),
@@ -163,9 +156,7 @@ extension ExtensionsExtensions on Iterable<ExtensionElement> {
         if (field != null && !field.isStatic) {
           result.add(
             _NotInstantiatedExtensionWithMember(
-              // TODO(paulberry): eliminate this cast by changing the
-              // extension to apply only to `Iterable<ExtensionElementImpl>`.
-              extension as ExtensionElementImpl,
+              extension,
               getter: field.getter,
               setter: field.setter,
             ),
@@ -175,12 +166,7 @@ extension ExtensionsExtensions on Iterable<ExtensionElement> {
         var method = extension.getMethod(baseName.name);
         if (method != null && !method.isStatic) {
           result.add(
-            _NotInstantiatedExtensionWithMember(
-              // TODO(paulberry): eliminate this cast by changing the
-              // extension to apply only to `Iterable<ExtensionElementImpl>`.
-              extension as ExtensionElementImpl,
-              getter: method,
-            ),
+            _NotInstantiatedExtensionWithMember(extension, getter: method),
           );
         }
       }
@@ -192,7 +178,7 @@ extension ExtensionsExtensions on Iterable<ExtensionElement> {
   /// with name [name].
   List<_ExtensionWithMemberWithName> havingStaticMemberWithName(Name name) {
     var result = <_ExtensionWithMemberWithName>[];
-    for (var extension in this) {
+    for (var extension in cast<ExtensionElementImpl>()) {
       if (!name.isAccessibleFor(extension.library.uri)) {
         continue;
       }
@@ -200,36 +186,21 @@ extension ExtensionsExtensions on Iterable<ExtensionElement> {
       var getter = extension.getGetter(name.name);
       if (getter != null && getter.isStatic) {
         result.add(
-          _ExtensionWithMemberWithName(
-            // TODO(paulberry): eliminate this cast by changing the
-            // extension to apply only to `Iterable<ExtensionElementImpl>`.
-            extension: extension as ExtensionElementImpl,
-            member: getter as GetterElementImpl,
-          ),
+          _ExtensionWithMemberWithName(extension: extension, member: getter),
         );
       }
 
       var setter = extension.getSetter(name.name);
       if (setter != null && setter.isStatic) {
         result.add(
-          _ExtensionWithMemberWithName(
-            // TODO(paulberry): eliminate this cast by changing the
-            // extension to apply only to `Iterable<ExtensionElementImpl>`.
-            extension: extension as ExtensionElementImpl,
-            member: setter as SetterElementImpl,
-          ),
+          _ExtensionWithMemberWithName(extension: extension, member: setter),
         );
       }
 
       var method = extension.getMethod(name.name);
       if (method != null && method.isStatic) {
         result.add(
-          _ExtensionWithMemberWithName(
-            // TODO(paulberry): eliminate this cast by changing the
-            // extension to apply only to `Iterable<ExtensionElementImpl>`.
-            extension: extension as ExtensionElementImpl,
-            member: method as MethodElementImpl,
-          ),
+          _ExtensionWithMemberWithName(extension: extension, member: method),
         );
       }
     }
@@ -242,13 +213,15 @@ extension NotInstantiatedExtensionsExtensions<R>
   /// Extensions that can be applied, within [targetLibrary], to [targetType].
   List<R> applicableTo({
     required LibraryElement targetLibrary,
-    required TypeImpl targetType,
+    required DartType targetType,
   }) {
+    targetLibrary as LibraryElementImpl;
+    targetType as TypeImpl;
+
     if (identical(targetType, NeverTypeImpl.instance)) {
       return <R>[];
     }
 
-    targetLibrary as LibraryElementImpl;
     var typeSystem = targetLibrary.typeSystem;
     var genericMetadataIsEnabled = targetLibrary.featureSet.isEnabled(
       Feature.generic_metadata,