[cfe][PrimaryConstructors] Use Object? as default for declaring parameter type inference

This adds a InferenceDefaultType enum to ensure that (declaring) parameter types are inferred as `Object?` instead of `dynamic`.

Part of #61700

Change-Id: If64fef6b6621c7cd110f8ce418a952f8e05474af
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/478360
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>

pkg/front_end/lib/src/builder/formal_parameter_builder.dart

@@ -35,6 +35,7 @@ import '../source/source_factory_builder.dart';
 import '../source/source_library_builder.dart';
 import '../source/source_member_builder.dart';
 import '../source/source_property_builder.dart';
+import '../util/helpers.dart';
 import 'builder.dart';
 import 'declaration_builders.dart';
 import 'omitted_type_builder.dart';
@@ -278,7 +279,9 @@ class FormalParameterBuilder extends NamedBuilderImpl
     return new FormalParameterBuilder(
       kind: kind,
       modifiers: modifiers | Modifiers.InitializingFormal,
-      type: builderFactory.addInferableType(),
+      type: builderFactory.addInferableType(
+        InferenceDefaultType.NullableObject,
+      ),
       name: name,
       fileOffset: fileOffset,
       nameOffset: nameOffset,

pkg/front_end/lib/src/builder/omitted_type_builder.dart

@@ -12,6 +12,7 @@ import '../kernel/type_algorithms.dart';
 import '../source/source_library_builder.dart';
 import '../source/source_loader.dart';
 import '../source/type_parameter_factory.dart';
+import '../util/helpers.dart';
 import 'declaration_builders.dart';
 import 'inferable_type_builder.dart';
 import 'library_builder.dart';
@@ -161,6 +162,10 @@ class ImplicitTypeBuilder extends OmittedTypeBuilderImpl {
 class InferableTypeBuilder extends OmittedTypeBuilderImpl
     with InferableTypeBuilderMixin
     implements InferableType {
+  final InferenceDefaultType inferenceDefaultType;
+
+  InferableTypeBuilder(this.inferenceDefaultType);
+
   @override
   DartType build(
     LibraryBuilder library,
@@ -229,7 +234,12 @@ class InferableTypeBuilder extends OmittedTypeBuilderImpl
       if (inferable != null) {
         inferable.inferTypes(hierarchy);
       } else {
-        registerInferredType(const DynamicType());
+        switch (inferenceDefaultType) {
+          case InferenceDefaultType.NullableObject:
+            registerInferredType(hierarchy.coreTypes.objectNullableRawType);
+          case InferenceDefaultType.Dynamic:
+            registerInferredType(const DynamicType());
+        }
       }
       assert(hasType, "No type computed for $this");
     }
@@ -273,8 +283,12 @@ abstract class Inferable {
 class InferableTypes {
   final List<InferableType> _inferableTypes = [];
 
-  InferableTypeBuilder addInferableType() {
-    InferableTypeBuilder typeBuilder = new InferableTypeBuilder();
+  InferableTypeBuilder addInferableType(
+    InferenceDefaultType inferenceDefaultType,
+  ) {
+    InferableTypeBuilder typeBuilder = new InferableTypeBuilder(
+      inferenceDefaultType,
+    );
     registerInferableType(typeBuilder);
     return typeBuilder;
   }

pkg/front_end/lib/src/fragment/enum_element.dart

@@ -477,7 +477,9 @@ class EnumElementFragment implements Fragment {
 
   EnumElementDeclaration? _declaration;
 
-  final TypeBuilder type = new InferableTypeBuilder();
+  final TypeBuilder type = new InferableTypeBuilder(
+    InferenceDefaultType.Dynamic,
+  );
 
   @override
   late final UriOffsetLength uriOffset = new UriOffsetLength(

pkg/front_end/lib/src/fragment/field/declaration.dart

@@ -37,6 +37,7 @@ import '../../source/type_parameter_factory.dart';
 import '../../type_inference/inference_results.dart';
 import '../../type_inference/type_inference_engine.dart';
 import '../../type_inference/type_inferrer.dart';
+import '../../util/helpers.dart';
 import '../fragment.dart';
 import '../getter/declaration.dart';
 import '../setter/declaration.dart';
@@ -277,6 +278,9 @@ class RegularFieldDeclaration
     _encoding.type = value;
   }
 
+  @override
+  InferenceDefaultType get inferenceDefaultType => InferenceDefaultType.Dynamic;
+
   @override
   void buildBody(CoreTypes coreTypes, Expression? initializer) {
     assert(!hasBodyBeenBuilt, "Body has already been built for $this.");
@@ -361,6 +365,7 @@ class RegularFieldDeclaration
             bodyBuilderContext: bodyBuilderContext,
             declaredFieldType: fieldType,
             token: token,
+            inferenceDefaultType: inferenceDefaultType,
           );
           buildBody(classHierarchy.coreTypes, initializer);
         }
@@ -374,6 +379,7 @@ class RegularFieldDeclaration
     required BodyBuilderContext bodyBuilderContext,
     DartType? declaredFieldType,
     required Token token,
+    required InferenceDefaultType inferenceDefaultType,
   }) {
     LookupScope scope = _fragment.enclosingScope;
     ExpressionInferenceResult expressionInferenceResult = libraryBuilder.loader
@@ -391,6 +397,7 @@ class RegularFieldDeclaration
               .dataForTesting
               // Coverage-ignore(suite): Not run.
               ?.inferenceData,
+          inferenceDefaultType: inferenceDefaultType,
         );
     if (computeSharedExpressionForTesting) {
       // Coverage-ignore-block(suite): Not run.
@@ -646,6 +653,7 @@ class RegularFieldDeclaration
         libraryBuilder: libraryBuilder,
         bodyBuilderContext: createBodyBuilderContext(),
         token: token,
+        inferenceDefaultType: InferenceDefaultType.Dynamic,
       );
     } else {
       return (const DynamicType(), null);
@@ -948,6 +956,8 @@ mixin FieldFragmentDeclarationMixin implements FieldFragmentDeclaration {
 
   Expression? get cachedFieldInitializer => _fieldInitializerCache;
 
+  InferenceDefaultType get inferenceDefaultType;
+
   @override
   void buildFieldInitializer({
     required TypeInferrer typeInferrer,
@@ -966,6 +976,7 @@ mixin FieldFragmentDeclarationMixin implements FieldFragmentDeclaration {
               fileUri: fileUri,
               declaredType: fieldType,
               initializer: initializer,
+              inferenceDefaultType: inferenceDefaultType,
             )
             .expression;
         _hasInitializerBeenComputed = true;

pkg/front_end/lib/src/fragment/fragment.dart

@@ -63,6 +63,7 @@ import '../source/source_type_parameter_builder.dart';
 import '../source/type_parameter_factory.dart';
 import '../type_inference/inference_results.dart';
 import '../type_inference/type_inference_engine.dart';
+import '../util/helpers.dart';
 import 'constructor/declaration.dart';
 import 'factory/declaration.dart';
 import 'field/declaration.dart';

pkg/front_end/lib/src/fragment/primary_constructor_field.dart

@@ -463,16 +463,22 @@ class PrimaryConstructorFieldDeclaration
             bodyBuilderContext: createBodyBuilderContext(),
             startToken: token,
             isLate: false,
+            inferenceDefaultType: inferenceDefaultType,
           );
       return (
         expressionInferenceResult.inferredType,
         expressionInferenceResult.expression,
       );
     } else {
-      return (const DynamicType(), null);
+      assert(inferenceDefaultType == InferenceDefaultType.NullableObject);
+      return (classHierarchy.coreTypes.objectNullableRawType, null);
     }
   }
 
+  @override
+  InferenceDefaultType get inferenceDefaultType =>
+      InferenceDefaultType.NullableObject;
+
   @override
   Initializer takePrimaryConstructorFieldInitializer() {
     throw new UnsupportedError(

pkg/front_end/lib/src/kernel/resolver.dart

@@ -47,6 +47,7 @@ import '../type_inference/type_inference_engine.dart';
 import '../type_inference/type_inferrer.dart'
     show TypeInferrer, InferredFunctionBody;
 import '../type_inference/type_schema.dart';
+import '../util/helpers.dart';
 import 'assigned_variables_impl.dart';
 import 'benchmarker.dart' show Benchmarker, BenchmarkSubdivides;
 import 'body_builder.dart';
@@ -230,6 +231,7 @@ class Resolver {
             fileUri: fileUri,
             declaredType: const UnknownType(),
             initializer: initializer,
+            inferenceDefaultType: InferenceDefaultType.Dynamic,
           );
       initializer = inferenceResult.expression;
       fieldType = inferenceResult.inferredType;
@@ -249,6 +251,7 @@ class Resolver {
     DartType? declaredFieldType,
     required Token startToken,
     required InferenceDataForTesting? inferenceDataForTesting,
+    required InferenceDefaultType inferenceDefaultType,
   }) {
     _ResolverContext context = new _ResolverContext(
       typeInferenceEngine: _typeInferenceEngine,
@@ -276,6 +279,7 @@ class Resolver {
           fileUri: fileUri,
           declaredType: declaredFieldType,
           initializer: result.initializer,
+          inferenceDefaultType: inferenceDefaultType,
         );
     context.performBacklog(result.annotations);
     return expressionInferenceResult;

pkg/front_end/lib/src/source/fragment_factory.dart

@@ -21,6 +21,7 @@ import '../builder/nullability_builder.dart';
 import '../builder/omitted_type_builder.dart';
 import '../builder/type_builder.dart';
 import '../fragment/fragment.dart';
+import '../util/helpers.dart';
 import 'offset_map.dart';
 import 'source_type_parameter_builder.dart';
 import 'type_parameter_factory.dart';
@@ -516,7 +517,9 @@ abstract class FragmentFactory {
 
   TypeBuilder addVoidType(int charOffset);
 
-  InferableTypeBuilder addInferableType();
+  InferableTypeBuilder addInferableType(
+    InferenceDefaultType inferenceDefaultType,
+  );
 
   TypeParameterFragment addNominalParameter({
     required List<MetadataBuilder>? metadata,

pkg/front_end/lib/src/source/fragment_factory_impl.dart

@@ -42,6 +42,7 @@ import '../builder/omitted_type_builder.dart';
 import '../builder/type_builder.dart';
 import '../builder/void_type_builder.dart';
 import '../fragment/fragment.dart';
+import '../util/helpers.dart';
 import '../util/local_stack.dart';
 import 'fragment_factory.dart';
 import 'name_space_builder.dart';
@@ -758,7 +759,7 @@ class FragmentFactoryImpl implements FragmentFactory {
     );
   }
 
-  Uri _resolve(Uri baseUri, String? uri, int uriOffset, {isPart = false}) {
+  Uri _resolve(Uri baseUri, String? uri, int uriOffset, {bool isPart = false}) {
     if (uri == null) {
       // Coverage-ignore-block(suite): Not run.
       _problemReporting.addProblem(
@@ -1459,7 +1460,7 @@ class FragmentFactoryImpl implements FragmentFactory {
       startOffset: startOffset,
       formalsOffset: formalsOffset,
       modifiers: isConst ? Modifiers.Const : Modifiers.empty,
-      returnType: addInferableType(),
+      returnType: addInferableType(InferenceDefaultType.Dynamic),
       typeParameterNameSpace: typeParameterNameSpace,
       typeParameterScope: typeParameterScope.lookupScope,
       formals: formals,
@@ -1545,7 +1546,7 @@ class FragmentFactoryImpl implements FragmentFactory {
       endOffset: endOffset,
       modifiers: modifiers - Modifiers.Abstract,
       metadata: metadata,
-      returnType: addInferableType(),
+      returnType: addInferableType(InferenceDefaultType.Dynamic),
       typeParameters: typeParameters,
       typeParameterNameSpace: typeParameterNameSpace,
       enclosingScope: _declarationFragments.current.bodyScope,
@@ -1925,7 +1926,7 @@ class FragmentFactoryImpl implements FragmentFactory {
       isTopLevel: enclosingDeclaration == null,
       metadata: metadata,
       modifiers: modifiers,
-      returnType: returnType ?? addInferableType(),
+      returnType: returnType ?? addInferableType(InferenceDefaultType.Dynamic),
       declaredTypeParameters: typeParameters,
       typeParameterNameSpace: typeParameterNameSpace,
       enclosingScope: enclosingDeclaration?.bodyScope ?? _compilationUnitScope,
@@ -2086,7 +2087,7 @@ class FragmentFactoryImpl implements FragmentFactory {
       isTopLevel: enclosingDeclaration == null,
       metadata: metadata,
       modifiers: modifiers,
-      returnType: returnType ?? addInferableType(),
+      returnType: returnType ?? addInferableType(InferenceDefaultType.Dynamic),
       declaredTypeParameters: typeParameters,
       typeParameterNameSpace: typeParameterNameSpace,
       enclosingScope: enclosingDeclaration?.bodyScope ?? _compilationUnitScope,
@@ -2136,7 +2137,7 @@ class FragmentFactoryImpl implements FragmentFactory {
           metadata: metadata,
           modifiers: modifiers,
           isTopLevel: isTopLevel,
-          type: type ?? addInferableType(),
+          type: type ?? addInferableType(InferenceDefaultType.Dynamic),
           name: info.identifier.name,
           nameOffset: info.identifier.nameOffset,
           endOffset: info.endOffset,
@@ -2441,8 +2442,12 @@ class FragmentFactoryImpl implements FragmentFactory {
   }
 
   @override
-  InferableTypeBuilder addInferableType() {
-    return _compilationUnit.loader.inferableTypes.addInferableType();
+  InferableTypeBuilder addInferableType(
+    InferenceDefaultType inferenceDefaultType,
+  ) {
+    return _compilationUnit.loader.inferableTypes.addInferableType(
+      inferenceDefaultType,
+    );
   }
 
   void _addFragment(Fragment fragment) {

pkg/front_end/lib/src/source/outline_builder.dart

@@ -54,6 +54,7 @@ import '../builder/record_type_builder.dart';
 import '../builder/type_builder.dart';
 import '../fragment/fragment.dart';
 import '../kernel/utils.dart';
+import '../util/helpers.dart';
 import 'check_helper.dart';
 import 'fragment_factory.dart';
 import 'offset_map.dart';
@@ -3046,11 +3047,7 @@ class OutlineBuilder extends StackListenerImpl {
           metadata: metadata,
           kind: kind,
           modifiers: modifiers,
-          type:
-              type ??
-              (memberKind.isParameterInferable(libraryFeatures)
-                  ? _builderFactory.addInferableType()
-                  : const ImplicitTypeBuilder()),
+          type: type ?? _createOmittedParameterTypeBuilder(memberKind),
           name: parameterName,
           publicName: publicName,
           hasThis: thisKeyword != null,
@@ -3065,6 +3062,47 @@ class OutlineBuilder extends StackListenerImpl {
     }
   }
 
+  /// Creates the [TypeBuilder] use for an omitted parameter type on the given
+  /// member [kind].
+  TypeBuilder _createOmittedParameterTypeBuilder(MemberKind kind) {
+    switch (kind) {
+      case MemberKind.Catch:
+      case MemberKind.FunctionTypeAlias:
+      case MemberKind.Factory:
+      case MemberKind.FunctionTypedParameter:
+      case MemberKind.GeneralizedFunctionType:
+      case MemberKind.Local:
+      case MemberKind.StaticMethod:
+      case MemberKind.TopLevelMethod:
+      case MemberKind.ExtensionNonStaticMethod:
+      case MemberKind.ExtensionStaticMethod:
+      case MemberKind.ExtensionTypeStaticMethod:
+        // Parameter type is not inferred.
+        return const ImplicitTypeBuilder();
+      case MemberKind.NonStaticMethod:
+      case MemberKind.ExtensionTypeNonStaticMethod:
+      // TODO(eernst): Write a test such that this does run.
+      case MemberKind.AnonymousMethod:
+      // These can be inferred but cannot hold parameters so the cases are
+      // dead code:
+      case MemberKind.NonStaticField:
+      case MemberKind.StaticField:
+      case MemberKind.TopLevelField:
+        // Parameter type is inferred with `dynamic` as default.
+        return _builderFactory.addInferableType(InferenceDefaultType.Dynamic);
+      case MemberKind.PrimaryConstructor:
+        if (libraryFeatures.primaryConstructors.isEnabled) {
+          // Parameter type is inferred with `Object?` as default.
+          return _builderFactory.addInferableType(
+            InferenceDefaultType.NullableObject,
+          );
+        } else {
+          // Parameter type is not inferred.
+          return const ImplicitTypeBuilder();
+        }
+    }
+  }
+
   @override
   void beginFormalParameterDefaultValueExpression() {
     _insideOfFormalParameterType = false;
@@ -4781,38 +4819,6 @@ class OutlineBuilder extends StackListenerImpl {
   }
 }
 
-extension on MemberKind {
-  /// Returns `true` if a parameter occurring in this context can be inferred.
-  bool isParameterInferable(LibraryFeatures libraryFeatures) {
-    switch (this) {
-      case MemberKind.Catch:
-      case MemberKind.FunctionTypeAlias:
-      case MemberKind.Factory:
-      case MemberKind.FunctionTypedParameter:
-      case MemberKind.GeneralizedFunctionType:
-      case MemberKind.Local:
-      case MemberKind.StaticMethod:
-      case MemberKind.TopLevelMethod:
-      case MemberKind.ExtensionNonStaticMethod:
-      case MemberKind.ExtensionStaticMethod:
-      case MemberKind.ExtensionTypeStaticMethod:
-        return false;
-      case MemberKind.NonStaticMethod:
-      case MemberKind.ExtensionTypeNonStaticMethod:
-      // TODO(eernst): Write a test such that this does run.
-      case MemberKind.AnonymousMethod:
-      // These can be inferred but cannot hold parameters so the cases are
-      // dead code:
-      case MemberKind.NonStaticField:
-      case MemberKind.StaticField:
-      case MemberKind.TopLevelField:
-        return true;
-      case MemberKind.PrimaryConstructor:
-        return libraryFeatures.primaryConstructors.isEnabled;
-    }
-  }
-}
-
 class EnumConstantInfo {
   final List<MetadataBuilder>? metadata;
   final String name;

pkg/front_end/lib/src/source/source_enum_builder.dart

@@ -45,6 +45,7 @@ import '../kernel/kernel_helper.dart';
 import '../kernel/member_covariance.dart';
 import '../kernel/type_algorithms.dart';
 import '../kernel/utils.dart';
+import '../util/helpers.dart';
 import 'builder_factory.dart';
 import 'name_scheme.dart';
 import 'name_space_builder.dart';
@@ -311,7 +312,9 @@ class SourceEnumBuilder extends SourceClassBuilder {
 
       ConstructorDeclaration constructorDeclaration =
           new DefaultEnumConstructorDeclaration(
-            returnType: libraryBuilder.loader.inferableTypes.addInferableType(),
+            returnType: libraryBuilder.loader.inferableTypes.addInferableType(
+              InferenceDefaultType.Dynamic,
+            ),
             formals: [indexFormalParameterBuilder, nameFormalParameterBuilder],
             fileUri: fileUri,
             fileOffset: fileOffset,

pkg/front_end/lib/src/type_inference/inference_visitor.dart

@@ -60,6 +60,7 @@ import '../kernel/late_lowering.dart' as late_lowering;
 import '../source/check_helper.dart';
 import '../source/source_constructor_builder.dart';
 import '../source/source_library_builder.dart';
+import '../util/helpers.dart';
 import 'closure_context.dart';
 import 'context_allocation_strategy.dart';
 import 'external_ast_helper.dart';
@@ -14866,7 +14867,12 @@ class InferenceVisitorImpl extends InferenceVisitorBase
   SharedTypeView variableTypeFromInitializerType(SharedTypeView type) {
     // TODO(paulberry): make a test verifying that we don't need to pass
     // `forSyntheticVariable: true` (and possibly a language issue)
-    return new SharedTypeView(inferDeclarationType(type.unwrapTypeView()));
+    return new SharedTypeView(
+      inferDeclarationType(
+        type.unwrapTypeView(),
+        inferenceDefaultType: InferenceDefaultType.Dynamic,
+      ),
+    );
   }
 
   @override
@@ -17104,6 +17110,7 @@ class InferenceVisitorImpl extends InferenceVisitorBase
       inferredType = inferDeclarationType(
         initializerResult.inferredType,
         forSyntheticVariable: node.name == null,
+        inferenceDefaultType: InferenceDefaultType.Dynamic,
       );
     } else {
       inferredType = const DynamicType();

pkg/front_end/lib/src/type_inference/inference_visitor_base.dart

@@ -1654,15 +1654,22 @@ abstract class InferenceVisitorBase implements InferenceVisitor {
   DartType inferDeclarationType(
     DartType initializerType, {
     bool forSyntheticVariable = false,
+    required InferenceDefaultType inferenceDefaultType,
   }) {
     if (forSyntheticVariable) {
       return initializerType;
     } else if (initializerType is NullType) {
-      // If the initializer type is Null or bottom, the inferred type is
-      // dynamic.
-      // TODO(paulberry): this rule is inherited from analyzer behavior but is
-      // not spec'ed anywhere.
-      return const DynamicType();
+      switch (inferenceDefaultType) {
+        case InferenceDefaultType.NullableObject:
+          // For primary constructors, `Object?` used in this case.
+          return coreTypes.objectNullableRawType;
+        case InferenceDefaultType.Dynamic:
+          // If the initializer type is Null or bottom, the inferred type is
+          // dynamic.
+          // TODO(paulberry): this rule is inherited from analyzer behavior but
+          //  is not spec'ed anywhere.
+          return const DynamicType();
+      }
     } else {
       return demoteTypeInLibrary(initializerType);
     }

pkg/front_end/lib/src/type_inference/type_inferrer.dart

@@ -15,6 +15,7 @@ import '../kernel/benchmarker.dart' show BenchmarkSubdivides, Benchmarker;
 import '../kernel/internal_ast.dart';
 import '../source/source_constructor_builder.dart';
 import '../source/source_library_builder.dart' show SourceLibraryBuilder;
+import '../util/helpers.dart';
 import 'closure_context.dart';
 import 'context_allocation_strategy.dart';
 import 'inference_results.dart';
@@ -43,11 +44,16 @@ abstract class TypeInferrer {
 
   AssignedVariablesImpl get assignedVariables;
 
-  /// Performs full type inference on the given field initializer.
+  /// Performs type inference on the given field [initializer] with the given
+  /// [declaredType], if any.
+  ///
+  /// When [declaredType] is `null` and the [initializer] has type `Null`, the
+  /// inferred field type is determined by [inferenceDefaultType].
   ExpressionInferenceResult inferFieldInitializer({
     required Uri fileUri,
     DartType? declaredType,
     required Expression initializer,
+    required InferenceDefaultType inferenceDefaultType,
   });
 
   /// Performs type inference on the given function body.
@@ -196,6 +202,7 @@ class TypeInferrerImpl implements TypeInferrer {
     required Uri fileUri,
     DartType? declaredType,
     required Expression initializer,
+    required InferenceDefaultType inferenceDefaultType,
   }) {
     InferenceVisitorBase visitor = _createInferenceVisitor(fileUri: fileUri);
     ExpressionInferenceResult initializerResult = visitor.inferExpression(
@@ -214,7 +221,10 @@ class TypeInferrerImpl implements TypeInferrer {
       // If the field has no declared type, compute the field type from the
       // inferred type.
       initializerResult = new ExpressionInferenceResult(
-        visitor.inferDeclarationType(initializerResult.inferredType),
+        visitor.inferDeclarationType(
+          initializerResult.inferredType,
+          inferenceDefaultType: inferenceDefaultType,
+        ),
         initializerResult.expression,
       );
     }
@@ -437,12 +447,14 @@ class TypeInferrerImplBenchmarked implements TypeInferrer {
     required Uri fileUri,
     DartType? declaredType,
     required Expression initializer,
+    required InferenceDefaultType inferenceDefaultType,
   }) {
     benchmarker.beginSubdivide(BenchmarkSubdivides.inferFieldInitializer);
     ExpressionInferenceResult result = impl.inferFieldInitializer(
       fileUri: fileUri,
       declaredType: declaredType,
       initializer: initializer,
+      inferenceDefaultType: inferenceDefaultType,
     );
     benchmarker.endSubdivide();
     return result;

pkg/front_end/lib/src/util/helpers.dart

@@ -62,3 +62,17 @@ int? tryParseRecordPositionalGetterName(String name, int positionalFieldCount) {
   }
   return null;
 }
+
+/// Enum used to determine which type to use as the default type for inference
+/// of an omitted type declaration.
+///
+/// This is use for instance when a field or parameter has no type annotation
+/// and no initializer/default value, or when the initializer/default has type
+/// `Null`.
+enum InferenceDefaultType {
+  /// Use `Object?` as the inferred type.
+  NullableObject,
+
+  /// Use `dynamic` as the inferred type.
+  Dynamic,
+}

pkg/front_end/testcases/general/omitted_parameter_type.dart

@@ -0,0 +1,109 @@
+// Copyright (c) 2026, 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.
+
+typedef void Typedef1(a,{b});
+
+method0(a, {b = 0}) {
+  int x = a;
+  String y = a; // Ok
+  int z = b;
+  String w = b; // Ok
+}
+
+class SuperClass {
+  void method(void f(a,{b})) {
+
+    local(a, {b = 0}) {
+      int x = a;
+      String y = a; // Ok
+      int z = b;
+      String w = b; // Ok
+    }
+
+    try {} catch (e, s) {}
+  }
+
+  void method1(int a, {int? b}) {}
+}
+
+class SubClass extends SuperClass {
+  SubClass();
+
+  SubClass.constructor1(a, {b = 0}) {
+    int x = a;
+    String y = a; // Ok
+    int z = b;
+    String w = b; // Ok
+  }
+
+  SubClass.constructor2(int x, String y, int z, String w);
+
+  SubClass.constructor3(a, {b = 0}) : this.constructor2(a, a, b, b); // Ok
+
+  factory SubClass.constructor4(a, {b = 0}) {
+    int x = a;
+    String y = a; // Ok
+    int z = b;
+    String w = b; // Ok
+
+    return SubClass();
+  }
+
+  method1(a, {b}) {
+    int x = a;
+    String y = a; // Error
+    int? z = b;
+    String? w = b; // Error
+  }
+
+  method2(a, {b = 0}) {
+    int x = a;
+    String y = a; // Ok
+    int z = b;
+    String w = b; // Ok
+  }
+
+  static method3(a, {b = 0}) {
+    int x = a;
+    String y = a; // Ok
+    int z = b;
+    String w = b; // Ok
+  }
+}
+
+extension on int {
+  method1(a, {b = 0}) {
+    int x = a;
+    String y = a; // Ok
+    int z = b;
+    String w = b; // Ok
+  }
+
+  static method2(a, {b = 0}) {
+    int x = a;
+    String y = a; // Ok
+    int z = b;
+    String w = b; // Ok
+  }
+}
+
+extension type SuperExtensionType(int i) {
+  void method3(int a, {int? b}) {}
+}
+
+extension type SubExtensionType(int i) implements SuperExtensionType {
+  method3(a, {b}) {
+    int x = a;
+    String y = a; // Ok
+    int? z = b;
+    String? w = b; // Ok
+  }
+
+  method4(a, {b = 0}) {
+    int x = a;
+    String y = a; // Ok
+    int z = b;
+    String w = b; // Ok
+  }
+}

pkg/front_end/testcases/general/omitted_parameter_type.dart.strong.expect

@@ -0,0 +1,158 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/omitted_parameter_type.dart:55:16: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
+//     String y = a; // Error
+//                ^
+//
+// pkg/front_end/testcases/general/omitted_parameter_type.dart:57:17: Error: A value of type 'int?' can't be assigned to a variable of type 'String?'.
+//     String? w = b; // Error
+//                 ^
+//
+import self as self;
+import "dart:core" as core;
+
+typedef Typedef1 = (dynamic, {b: dynamic}) → void;
+class SuperClass extends core::Object {
+  synthetic constructor •() → self::SuperClass
+    : super core::Object::•()
+    ;
+  method method((dynamic, {b: dynamic}) → void f) → void {
+    function local(dynamic a, {dynamic b = #C1}) → Null {
+      core::int x = a as{TypeError,ForDynamic} core::int;
+      core::String y = a as{TypeError,ForDynamic} core::String;
+      core::int z = b as{TypeError,ForDynamic} core::int;
+      core::String w = b as{TypeError,ForDynamic} core::String;
+    }
+    try {
+    }
+    on core::Object catch(final core::Object e, final core::StackTrace s) {
+    }
+  }
+  method method1(core::int a, {core::int? b = #C2}) → void {}
+}
+class SubClass extends self::SuperClass {
+  constructor •() → self::SubClass
+    : super self::SuperClass::•()
+    ;
+  constructor constructor1(dynamic a, {dynamic b = #C1}) → self::SubClass
+    : super self::SuperClass::•() {
+    core::int x = a as{TypeError,ForDynamic} core::int;
+    core::String y = a as{TypeError,ForDynamic} core::String;
+    core::int z = b as{TypeError,ForDynamic} core::int;
+    core::String w = b as{TypeError,ForDynamic} core::String;
+  }
+  constructor constructor2(core::int x, core::String y, core::int z, core::String w) → self::SubClass
+    : super self::SuperClass::•()
+    ;
+  constructor constructor3(dynamic a, {dynamic b = #C1}) → self::SubClass
+    : this self::SubClass::constructor2(a as{TypeError,ForDynamic} core::int, a as{TypeError,ForDynamic} core::String, b as{TypeError,ForDynamic} core::int, b as{TypeError,ForDynamic} core::String)
+    ;
+  static factory constructor4(dynamic a, {dynamic b = #C1}) → self::SubClass {
+    core::int x = a as{TypeError,ForDynamic} core::int;
+    core::String y = a as{TypeError,ForDynamic} core::String;
+    core::int z = b as{TypeError,ForDynamic} core::int;
+    core::String w = b as{TypeError,ForDynamic} core::String;
+    return new self::SubClass::•();
+  }
+  method method1(core::int a, {core::int? b = #C2}) → void {
+    core::int x = a;
+    core::String y = invalid-expression "pkg/front_end/testcases/general/omitted_parameter_type.dart:55:16: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
+    String y = a; // Error
+               ^" in a as{TypeError} core::String;
+    core::int? z = b;
+    core::String? w = invalid-expression "pkg/front_end/testcases/general/omitted_parameter_type.dart:57:17: Error: A value of type 'int?' can't be assigned to a variable of type 'String?'.
+    String? w = b; // Error
+                ^" in b as{TypeError} core::String?;
+  }
+  method method2(dynamic a, {dynamic b = #C1}) → dynamic {
+    core::int x = a as{TypeError,ForDynamic} core::int;
+    core::String y = a as{TypeError,ForDynamic} core::String;
+    core::int z = b as{TypeError,ForDynamic} core::int;
+    core::String w = b as{TypeError,ForDynamic} core::String;
+  }
+  static method method3(dynamic a, {dynamic b = #C1}) → dynamic {
+    core::int x = a as{TypeError,ForDynamic} core::int;
+    core::String y = a as{TypeError,ForDynamic} core::String;
+    core::int z = b as{TypeError,ForDynamic} core::int;
+    core::String w = b as{TypeError,ForDynamic} core::String;
+  }
+}
+extension /* unnamed */ _extension#0 on core::int {
+  method method1 = self::_extension#0|method1;
+  method tearoff method1 = self::_extension#0|get#method1;
+  static method method2 = self::_extension#0|method2;
+}
+extension type SuperExtensionType(core::int i) {
+  abstract extension-type-member representation-field get i() → core::int;
+  method method3 = self::SuperExtensionType|method3;
+  method tearoff method3 = self::SuperExtensionType|get#method3;
+  constructor • = self::SuperExtensionType|constructor#;
+  constructor tearoff • = self::SuperExtensionType|constructor#_#new#tearOff;
+}
+extension type SubExtensionType(core::int i) implements self::SuperExtensionType% /* erasure=core::int, declared=! */ {
+  abstract extension-type-member representation-field get i() → core::int;
+  method method3 = self::SubExtensionType|method3;
+  method tearoff method3 = self::SubExtensionType|get#method3;
+  method method4 = self::SubExtensionType|method4;
+  method tearoff method4 = self::SubExtensionType|get#method4;
+  constructor • = self::SubExtensionType|constructor#;
+  constructor tearoff • = self::SubExtensionType|constructor#_#new#tearOff;
+}
+static method method0(dynamic a, {dynamic b = #C1}) → dynamic {
+  core::int x = a as{TypeError,ForDynamic} core::int;
+  core::String y = a as{TypeError,ForDynamic} core::String;
+  core::int z = b as{TypeError,ForDynamic} core::int;
+  core::String w = b as{TypeError,ForDynamic} core::String;
+}
+static extension-member method _extension#0|method1(lowered final core::int #this, dynamic a, {dynamic b = #C1}) → dynamic {
+  core::int x = a as{TypeError,ForDynamic} core::int;
+  core::String y = a as{TypeError,ForDynamic} core::String;
+  core::int z = b as{TypeError,ForDynamic} core::int;
+  core::String w = b as{TypeError,ForDynamic} core::String;
+}
+static extension-member method _extension#0|get#method1(lowered final core::int #this) → (dynamic, {b: dynamic}) → dynamic
+  return (dynamic a, {dynamic b = #C1}) → dynamic => self::_extension#0|method1(#this, a, b: b);
+static extension-member method _extension#0|method2(dynamic a, {dynamic b = #C1}) → dynamic {
+  core::int x = a as{TypeError,ForDynamic} core::int;
+  core::String y = a as{TypeError,ForDynamic} core::String;
+  core::int z = b as{TypeError,ForDynamic} core::int;
+  core::String w = b as{TypeError,ForDynamic} core::String;
+}
+static extension-type-member method SuperExtensionType|constructor#(core::int i) → self::SuperExtensionType% /* erasure=core::int, declared=! */ {
+  lowered final self::SuperExtensionType% /* erasure=core::int, declared=! */ #this = i;
+  return #this;
+}
+static extension-type-member synthetic method SuperExtensionType|constructor#_#new#tearOff(core::int i) → self::SuperExtensionType% /* erasure=core::int, declared=! */
+  return self::SuperExtensionType|constructor#(i);
+static extension-type-member method SuperExtensionType|method3(lowered final self::SuperExtensionType% /* erasure=core::int, declared=! */ #this, core::int a, {core::int? b = #C2}) → void {}
+static extension-type-member method SuperExtensionType|get#method3(lowered final self::SuperExtensionType% /* erasure=core::int, declared=! */ #this) → (core::int, {b: core::int?}) → void
+  return (core::int a, {core::int? b = #C2}) → void => self::SuperExtensionType|method3(#this, a, b: b);
+static extension-type-member method SubExtensionType|constructor#(core::int i) → self::SubExtensionType% /* erasure=core::int, declared=! */ {
+  lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this = i;
+  return #this;
+}
+static extension-type-member synthetic method SubExtensionType|constructor#_#new#tearOff(core::int i) → self::SubExtensionType% /* erasure=core::int, declared=! */
+  return self::SubExtensionType|constructor#(i);
+static extension-type-member method SubExtensionType|method3(lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this, dynamic a, {dynamic b = #C2}) → dynamic {
+  core::int x = a as{TypeError,ForDynamic} core::int;
+  core::String y = a as{TypeError,ForDynamic} core::String;
+  core::int? z = b as{TypeError,ForDynamic} core::int?;
+  core::String? w = b as{TypeError,ForDynamic} core::String?;
+}
+static extension-type-member method SubExtensionType|get#method3(lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this) → (dynamic, {b: dynamic}) → dynamic
+  return (dynamic a, {dynamic b = #C2}) → dynamic => self::SubExtensionType|method3(#this, a, b: b);
+static extension-type-member method SubExtensionType|method4(lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this, dynamic a, {dynamic b = #C1}) → dynamic {
+  core::int x = a as{TypeError,ForDynamic} core::int;
+  core::String y = a as{TypeError,ForDynamic} core::String;
+  core::int z = b as{TypeError,ForDynamic} core::int;
+  core::String w = b as{TypeError,ForDynamic} core::String;
+}
+static extension-type-member method SubExtensionType|get#method4(lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this) → (dynamic, {b: dynamic}) → dynamic
+  return (dynamic a, {dynamic b = #C1}) → dynamic => self::SubExtensionType|method4(#this, a, b: b);
+
+constants  {
+  #C1 = 0
+  #C2 = null
+}

pkg/front_end/testcases/general/omitted_parameter_type.dart.strong.modular.expect

@@ -0,0 +1,158 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/omitted_parameter_type.dart:55:16: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
+//     String y = a; // Error
+//                ^
+//
+// pkg/front_end/testcases/general/omitted_parameter_type.dart:57:17: Error: A value of type 'int?' can't be assigned to a variable of type 'String?'.
+//     String? w = b; // Error
+//                 ^
+//
+import self as self;
+import "dart:core" as core;
+
+typedef Typedef1 = (dynamic, {b: dynamic}) → void;
+class SuperClass extends core::Object {
+  synthetic constructor •() → self::SuperClass
+    : super core::Object::•()
+    ;
+  method method((dynamic, {b: dynamic}) → void f) → void {
+    function local(dynamic a, {dynamic b = #C1}) → Null {
+      core::int x = a as{TypeError,ForDynamic} core::int;
+      core::String y = a as{TypeError,ForDynamic} core::String;
+      core::int z = b as{TypeError,ForDynamic} core::int;
+      core::String w = b as{TypeError,ForDynamic} core::String;
+    }
+    try {
+    }
+    on core::Object catch(final core::Object e, final core::StackTrace s) {
+    }
+  }
+  method method1(core::int a, {core::int? b = #C2}) → void {}
+}
+class SubClass extends self::SuperClass {
+  constructor •() → self::SubClass
+    : super self::SuperClass::•()
+    ;
+  constructor constructor1(dynamic a, {dynamic b = #C1}) → self::SubClass
+    : super self::SuperClass::•() {
+    core::int x = a as{TypeError,ForDynamic} core::int;
+    core::String y = a as{TypeError,ForDynamic} core::String;
+    core::int z = b as{TypeError,ForDynamic} core::int;
+    core::String w = b as{TypeError,ForDynamic} core::String;
+  }
+  constructor constructor2(core::int x, core::String y, core::int z, core::String w) → self::SubClass
+    : super self::SuperClass::•()
+    ;
+  constructor constructor3(dynamic a, {dynamic b = #C1}) → self::SubClass
+    : this self::SubClass::constructor2(a as{TypeError,ForDynamic} core::int, a as{TypeError,ForDynamic} core::String, b as{TypeError,ForDynamic} core::int, b as{TypeError,ForDynamic} core::String)
+    ;
+  static factory constructor4(dynamic a, {dynamic b = #C1}) → self::SubClass {
+    core::int x = a as{TypeError,ForDynamic} core::int;
+    core::String y = a as{TypeError,ForDynamic} core::String;
+    core::int z = b as{TypeError,ForDynamic} core::int;
+    core::String w = b as{TypeError,ForDynamic} core::String;
+    return new self::SubClass::•();
+  }
+  method method1(core::int a, {core::int? b = #C2}) → void {
+    core::int x = a;
+    core::String y = invalid-expression "pkg/front_end/testcases/general/omitted_parameter_type.dart:55:16: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
+    String y = a; // Error
+               ^" in a as{TypeError} core::String;
+    core::int? z = b;
+    core::String? w = invalid-expression "pkg/front_end/testcases/general/omitted_parameter_type.dart:57:17: Error: A value of type 'int?' can't be assigned to a variable of type 'String?'.
+    String? w = b; // Error
+                ^" in b as{TypeError} core::String?;
+  }
+  method method2(dynamic a, {dynamic b = #C1}) → dynamic {
+    core::int x = a as{TypeError,ForDynamic} core::int;
+    core::String y = a as{TypeError,ForDynamic} core::String;
+    core::int z = b as{TypeError,ForDynamic} core::int;
+    core::String w = b as{TypeError,ForDynamic} core::String;
+  }
+  static method method3(dynamic a, {dynamic b = #C1}) → dynamic {
+    core::int x = a as{TypeError,ForDynamic} core::int;
+    core::String y = a as{TypeError,ForDynamic} core::String;
+    core::int z = b as{TypeError,ForDynamic} core::int;
+    core::String w = b as{TypeError,ForDynamic} core::String;
+  }
+}
+extension /* unnamed */ _extension#0 on core::int {
+  method method1 = self::_extension#0|method1;
+  method tearoff method1 = self::_extension#0|get#method1;
+  static method method2 = self::_extension#0|method2;
+}
+extension type SuperExtensionType(core::int i) {
+  abstract extension-type-member representation-field get i() → core::int;
+  method method3 = self::SuperExtensionType|method3;
+  method tearoff method3 = self::SuperExtensionType|get#method3;
+  constructor • = self::SuperExtensionType|constructor#;
+  constructor tearoff • = self::SuperExtensionType|constructor#_#new#tearOff;
+}
+extension type SubExtensionType(core::int i) implements self::SuperExtensionType% /* erasure=core::int, declared=! */ {
+  abstract extension-type-member representation-field get i() → core::int;
+  method method3 = self::SubExtensionType|method3;
+  method tearoff method3 = self::SubExtensionType|get#method3;
+  method method4 = self::SubExtensionType|method4;
+  method tearoff method4 = self::SubExtensionType|get#method4;
+  constructor • = self::SubExtensionType|constructor#;
+  constructor tearoff • = self::SubExtensionType|constructor#_#new#tearOff;
+}
+static method method0(dynamic a, {dynamic b = #C1}) → dynamic {
+  core::int x = a as{TypeError,ForDynamic} core::int;
+  core::String y = a as{TypeError,ForDynamic} core::String;
+  core::int z = b as{TypeError,ForDynamic} core::int;
+  core::String w = b as{TypeError,ForDynamic} core::String;
+}
+static extension-member method _extension#0|method1(lowered final core::int #this, dynamic a, {dynamic b = #C1}) → dynamic {
+  core::int x = a as{TypeError,ForDynamic} core::int;
+  core::String y = a as{TypeError,ForDynamic} core::String;
+  core::int z = b as{TypeError,ForDynamic} core::int;
+  core::String w = b as{TypeError,ForDynamic} core::String;
+}
+static extension-member method _extension#0|get#method1(lowered final core::int #this) → (dynamic, {b: dynamic}) → dynamic
+  return (dynamic a, {dynamic b = #C1}) → dynamic => self::_extension#0|method1(#this, a, b: b);
+static extension-member method _extension#0|method2(dynamic a, {dynamic b = #C1}) → dynamic {
+  core::int x = a as{TypeError,ForDynamic} core::int;
+  core::String y = a as{TypeError,ForDynamic} core::String;
+  core::int z = b as{TypeError,ForDynamic} core::int;
+  core::String w = b as{TypeError,ForDynamic} core::String;
+}
+static extension-type-member method SuperExtensionType|constructor#(core::int i) → self::SuperExtensionType% /* erasure=core::int, declared=! */ {
+  lowered final self::SuperExtensionType% /* erasure=core::int, declared=! */ #this = i;
+  return #this;
+}
+static extension-type-member synthetic method SuperExtensionType|constructor#_#new#tearOff(core::int i) → self::SuperExtensionType% /* erasure=core::int, declared=! */
+  return self::SuperExtensionType|constructor#(i);
+static extension-type-member method SuperExtensionType|method3(lowered final self::SuperExtensionType% /* erasure=core::int, declared=! */ #this, core::int a, {core::int? b = #C2}) → void {}
+static extension-type-member method SuperExtensionType|get#method3(lowered final self::SuperExtensionType% /* erasure=core::int, declared=! */ #this) → (core::int, {b: core::int?}) → void
+  return (core::int a, {core::int? b = #C2}) → void => self::SuperExtensionType|method3(#this, a, b: b);
+static extension-type-member method SubExtensionType|constructor#(core::int i) → self::SubExtensionType% /* erasure=core::int, declared=! */ {
+  lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this = i;
+  return #this;
+}
+static extension-type-member synthetic method SubExtensionType|constructor#_#new#tearOff(core::int i) → self::SubExtensionType% /* erasure=core::int, declared=! */
+  return self::SubExtensionType|constructor#(i);
+static extension-type-member method SubExtensionType|method3(lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this, dynamic a, {dynamic b = #C2}) → dynamic {
+  core::int x = a as{TypeError,ForDynamic} core::int;
+  core::String y = a as{TypeError,ForDynamic} core::String;
+  core::int? z = b as{TypeError,ForDynamic} core::int?;
+  core::String? w = b as{TypeError,ForDynamic} core::String?;
+}
+static extension-type-member method SubExtensionType|get#method3(lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this) → (dynamic, {b: dynamic}) → dynamic
+  return (dynamic a, {dynamic b = #C2}) → dynamic => self::SubExtensionType|method3(#this, a, b: b);
+static extension-type-member method SubExtensionType|method4(lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this, dynamic a, {dynamic b = #C1}) → dynamic {
+  core::int x = a as{TypeError,ForDynamic} core::int;
+  core::String y = a as{TypeError,ForDynamic} core::String;
+  core::int z = b as{TypeError,ForDynamic} core::int;
+  core::String w = b as{TypeError,ForDynamic} core::String;
+}
+static extension-type-member method SubExtensionType|get#method4(lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this) → (dynamic, {b: dynamic}) → dynamic
+  return (dynamic a, {dynamic b = #C1}) → dynamic => self::SubExtensionType|method4(#this, a, b: b);
+
+constants  {
+  #C1 = 0
+  #C2 = null
+}

pkg/front_end/testcases/general/omitted_parameter_type.dart.strong.outline.expect

@@ -0,0 +1,80 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+typedef Typedef1 = (dynamic, {b: dynamic}) → void;
+class SuperClass extends core::Object {
+  synthetic constructor •() → self::SuperClass
+    ;
+  method method((dynamic, {b: dynamic}) → void f) → void
+    ;
+  method method1(core::int a, {core::int? b = null}) → void
+    ;
+}
+class SubClass extends self::SuperClass {
+  constructor •() → self::SubClass
+    ;
+  constructor constructor1(dynamic a, {dynamic b = 0}) → self::SubClass
+    ;
+  constructor constructor2(core::int x, core::String y, core::int z, core::String w) → self::SubClass
+    ;
+  constructor constructor3(dynamic a, {dynamic b = 0}) → self::SubClass
+    ;
+  static factory constructor4(dynamic a, {dynamic b = 0}) → self::SubClass
+    ;
+  method method1(core::int a, {core::int? b = null}) → void
+    ;
+  method method2(dynamic a, {dynamic b = 0}) → dynamic
+    ;
+  static method method3(dynamic a, {has-declared-initializer dynamic b}) → dynamic
+    ;
+}
+extension /* unnamed */ _extension#0 on core::int {
+  method method1 = self::_extension#0|method1;
+  method tearoff method1 = self::_extension#0|get#method1;
+  static method method2 = self::_extension#0|method2;
+}
+extension type SuperExtensionType(core::int i) {
+  abstract extension-type-member representation-field get i() → core::int;
+  method method3 = self::SuperExtensionType|method3;
+  method tearoff method3 = self::SuperExtensionType|get#method3;
+  constructor • = self::SuperExtensionType|constructor#;
+  constructor tearoff • = self::SuperExtensionType|constructor#_#new#tearOff;
+}
+extension type SubExtensionType(core::int i) implements self::SuperExtensionType% /* erasure=core::int, declared=! */ {
+  abstract extension-type-member representation-field get i() → core::int;
+  method method3 = self::SubExtensionType|method3;
+  method tearoff method3 = self::SubExtensionType|get#method3;
+  method method4 = self::SubExtensionType|method4;
+  method tearoff method4 = self::SubExtensionType|get#method4;
+  constructor • = self::SubExtensionType|constructor#;
+  constructor tearoff • = self::SubExtensionType|constructor#_#new#tearOff;
+}
+static method method0(dynamic a, {has-declared-initializer dynamic b}) → dynamic
+  ;
+static extension-member method _extension#0|method1(lowered final core::int #this, dynamic a, {has-declared-initializer dynamic b}) → dynamic
+  ;
+static extension-member method _extension#0|get#method1(lowered final core::int #this) → (dynamic, {b: dynamic}) → dynamic
+  return (dynamic a, {dynamic b}) → dynamic => self::_extension#0|method1(#this, a, b: b);
+static extension-member method _extension#0|method2(dynamic a, {has-declared-initializer dynamic b}) → dynamic
+  ;
+static extension-type-member method SuperExtensionType|constructor#(core::int i) → self::SuperExtensionType% /* erasure=core::int, declared=! */
+  ;
+static extension-type-member synthetic method SuperExtensionType|constructor#_#new#tearOff(core::int i) → self::SuperExtensionType% /* erasure=core::int, declared=! */
+  return self::SuperExtensionType|constructor#(i);
+static extension-type-member method SuperExtensionType|method3(lowered final self::SuperExtensionType% /* erasure=core::int, declared=! */ #this, core::int a, {core::int? b}) → void
+  ;
+static extension-type-member method SuperExtensionType|get#method3(lowered final self::SuperExtensionType% /* erasure=core::int, declared=! */ #this) → (core::int, {b: core::int?}) → void
+  return (core::int a, {core::int? b}) → void => self::SuperExtensionType|method3(#this, a, b: b);
+static extension-type-member method SubExtensionType|constructor#(core::int i) → self::SubExtensionType% /* erasure=core::int, declared=! */
+  ;
+static extension-type-member synthetic method SubExtensionType|constructor#_#new#tearOff(core::int i) → self::SubExtensionType% /* erasure=core::int, declared=! */
+  return self::SubExtensionType|constructor#(i);
+static extension-type-member method SubExtensionType|method3(lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this, dynamic a, {dynamic b}) → dynamic
+  ;
+static extension-type-member method SubExtensionType|get#method3(lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this) → (dynamic, {b: dynamic}) → dynamic
+  return (dynamic a, {dynamic b}) → dynamic => self::SubExtensionType|method3(#this, a, b: b);
+static extension-type-member method SubExtensionType|method4(lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this, dynamic a, {has-declared-initializer dynamic b}) → dynamic
+  ;
+static extension-type-member method SubExtensionType|get#method4(lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this) → (dynamic, {b: dynamic}) → dynamic
+  return (dynamic a, {dynamic b}) → dynamic => self::SubExtensionType|method4(#this, a, b: b);

pkg/front_end/testcases/general/omitted_parameter_type.dart.strong.transformed.expect

@@ -0,0 +1,158 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/omitted_parameter_type.dart:55:16: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
+//     String y = a; // Error
+//                ^
+//
+// pkg/front_end/testcases/general/omitted_parameter_type.dart:57:17: Error: A value of type 'int?' can't be assigned to a variable of type 'String?'.
+//     String? w = b; // Error
+//                 ^
+//
+import self as self;
+import "dart:core" as core;
+
+typedef Typedef1 = (dynamic, {b: dynamic}) → void;
+class SuperClass extends core::Object {
+  synthetic constructor •() → self::SuperClass
+    : super core::Object::•()
+    ;
+  method method((dynamic, {b: dynamic}) → void f) → void {
+    function local(dynamic a, {dynamic b = #C1}) → Null {
+      core::int x = a as{TypeError,ForDynamic} core::int;
+      core::String y = a as{TypeError,ForDynamic} core::String;
+      core::int z = b as{TypeError,ForDynamic} core::int;
+      core::String w = b as{TypeError,ForDynamic} core::String;
+    }
+    try {
+    }
+    on core::Object catch(final core::Object e, final core::StackTrace s) {
+    }
+  }
+  method method1(core::int a, {core::int? b = #C2}) → void {}
+}
+class SubClass extends self::SuperClass {
+  constructor •() → self::SubClass
+    : super self::SuperClass::•()
+    ;
+  constructor constructor1(dynamic a, {dynamic b = #C1}) → self::SubClass
+    : super self::SuperClass::•() {
+    core::int x = a as{TypeError,ForDynamic} core::int;
+    core::String y = a as{TypeError,ForDynamic} core::String;
+    core::int z = b as{TypeError,ForDynamic} core::int;
+    core::String w = b as{TypeError,ForDynamic} core::String;
+  }
+  constructor constructor2(core::int x, core::String y, core::int z, core::String w) → self::SubClass
+    : super self::SuperClass::•()
+    ;
+  constructor constructor3(dynamic a, {dynamic b = #C1}) → self::SubClass
+    : this self::SubClass::constructor2(a as{TypeError,ForDynamic} core::int, a as{TypeError,ForDynamic} core::String, b as{TypeError,ForDynamic} core::int, b as{TypeError,ForDynamic} core::String)
+    ;
+  static factory constructor4(dynamic a, {dynamic b = #C1}) → self::SubClass {
+    core::int x = a as{TypeError,ForDynamic} core::int;
+    core::String y = a as{TypeError,ForDynamic} core::String;
+    core::int z = b as{TypeError,ForDynamic} core::int;
+    core::String w = b as{TypeError,ForDynamic} core::String;
+    return new self::SubClass::•();
+  }
+  method method1(core::int a, {core::int? b = #C2}) → void {
+    core::int x = a;
+    core::String y = invalid-expression "pkg/front_end/testcases/general/omitted_parameter_type.dart:55:16: Error: A value of type 'int' can't be assigned to a variable of type 'String'.
+    String y = a; // Error
+               ^" in a as{TypeError} core::String;
+    core::int? z = b;
+    core::String? w = invalid-expression "pkg/front_end/testcases/general/omitted_parameter_type.dart:57:17: Error: A value of type 'int?' can't be assigned to a variable of type 'String?'.
+    String? w = b; // Error
+                ^" in b as{TypeError} core::String?;
+  }
+  method method2(dynamic a, {dynamic b = #C1}) → dynamic {
+    core::int x = a as{TypeError,ForDynamic} core::int;
+    core::String y = a as{TypeError,ForDynamic} core::String;
+    core::int z = b as{TypeError,ForDynamic} core::int;
+    core::String w = b as{TypeError,ForDynamic} core::String;
+  }
+  static method method3(dynamic a, {dynamic b = #C1}) → dynamic {
+    core::int x = a as{TypeError,ForDynamic} core::int;
+    core::String y = a as{TypeError,ForDynamic} core::String;
+    core::int z = b as{TypeError,ForDynamic} core::int;
+    core::String w = b as{TypeError,ForDynamic} core::String;
+  }
+}
+extension /* unnamed */ _extension#0 on core::int {
+  method method1 = self::_extension#0|method1;
+  method tearoff method1 = self::_extension#0|get#method1;
+  static method method2 = self::_extension#0|method2;
+}
+extension type SuperExtensionType(core::int i) {
+  abstract extension-type-member representation-field get i() → core::int;
+  method method3 = self::SuperExtensionType|method3;
+  method tearoff method3 = self::SuperExtensionType|get#method3;
+  constructor • = self::SuperExtensionType|constructor#;
+  constructor tearoff • = self::SuperExtensionType|constructor#_#new#tearOff;
+}
+extension type SubExtensionType(core::int i) implements self::SuperExtensionType% /* erasure=core::int, declared=! */ {
+  abstract extension-type-member representation-field get i() → core::int;
+  method method3 = self::SubExtensionType|method3;
+  method tearoff method3 = self::SubExtensionType|get#method3;
+  method method4 = self::SubExtensionType|method4;
+  method tearoff method4 = self::SubExtensionType|get#method4;
+  constructor • = self::SubExtensionType|constructor#;
+  constructor tearoff • = self::SubExtensionType|constructor#_#new#tearOff;
+}
+static method method0(dynamic a, {dynamic b = #C1}) → dynamic {
+  core::int x = a as{TypeError,ForDynamic} core::int;
+  core::String y = a as{TypeError,ForDynamic} core::String;
+  core::int z = b as{TypeError,ForDynamic} core::int;
+  core::String w = b as{TypeError,ForDynamic} core::String;
+}
+static extension-member method _extension#0|method1(lowered final core::int #this, dynamic a, {dynamic b = #C1}) → dynamic {
+  core::int x = a as{TypeError,ForDynamic} core::int;
+  core::String y = a as{TypeError,ForDynamic} core::String;
+  core::int z = b as{TypeError,ForDynamic} core::int;
+  core::String w = b as{TypeError,ForDynamic} core::String;
+}
+static extension-member method _extension#0|get#method1(lowered final core::int #this) → (dynamic, {b: dynamic}) → dynamic
+  return (dynamic a, {dynamic b = #C1}) → dynamic => self::_extension#0|method1(#this, a, b: b);
+static extension-member method _extension#0|method2(dynamic a, {dynamic b = #C1}) → dynamic {
+  core::int x = a as{TypeError,ForDynamic} core::int;
+  core::String y = a as{TypeError,ForDynamic} core::String;
+  core::int z = b as{TypeError,ForDynamic} core::int;
+  core::String w = b as{TypeError,ForDynamic} core::String;
+}
+static extension-type-member method SuperExtensionType|constructor#(core::int i) → self::SuperExtensionType% /* erasure=core::int, declared=! */ {
+  lowered final self::SuperExtensionType% /* erasure=core::int, declared=! */ #this = i;
+  return #this;
+}
+static extension-type-member synthetic method SuperExtensionType|constructor#_#new#tearOff(core::int i) → self::SuperExtensionType% /* erasure=core::int, declared=! */
+  return self::SuperExtensionType|constructor#(i);
+static extension-type-member method SuperExtensionType|method3(lowered final self::SuperExtensionType% /* erasure=core::int, declared=! */ #this, core::int a, {core::int? b = #C2}) → void {}
+static extension-type-member method SuperExtensionType|get#method3(lowered final self::SuperExtensionType% /* erasure=core::int, declared=! */ #this) → (core::int, {b: core::int?}) → void
+  return (core::int a, {core::int? b = #C2}) → void => self::SuperExtensionType|method3(#this, a, b: b);
+static extension-type-member method SubExtensionType|constructor#(core::int i) → self::SubExtensionType% /* erasure=core::int, declared=! */ {
+  lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this = i;
+  return #this;
+}
+static extension-type-member synthetic method SubExtensionType|constructor#_#new#tearOff(core::int i) → self::SubExtensionType% /* erasure=core::int, declared=! */
+  return self::SubExtensionType|constructor#(i);
+static extension-type-member method SubExtensionType|method3(lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this, dynamic a, {dynamic b = #C2}) → dynamic {
+  core::int x = a as{TypeError,ForDynamic} core::int;
+  core::String y = a as{TypeError,ForDynamic} core::String;
+  core::int? z = b as{TypeError,ForDynamic} core::int?;
+  core::String? w = b as{TypeError,ForDynamic} core::String?;
+}
+static extension-type-member method SubExtensionType|get#method3(lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this) → (dynamic, {b: dynamic}) → dynamic
+  return (dynamic a, {dynamic b = #C2}) → dynamic => self::SubExtensionType|method3(#this, a, b: b);
+static extension-type-member method SubExtensionType|method4(lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this, dynamic a, {dynamic b = #C1}) → dynamic {
+  core::int x = a as{TypeError,ForDynamic} core::int;
+  core::String y = a as{TypeError,ForDynamic} core::String;
+  core::int z = b as{TypeError,ForDynamic} core::int;
+  core::String w = b as{TypeError,ForDynamic} core::String;
+}
+static extension-type-member method SubExtensionType|get#method4(lowered final self::SubExtensionType% /* erasure=core::int, declared=! */ #this) → (dynamic, {b: dynamic}) → dynamic
+  return (dynamic a, {dynamic b = #C1}) → dynamic => self::SubExtensionType|method4(#this, a, b: b);
+
+constants  {
+  #C1 = 0
+  #C2 = null
+}

pkg/front_end/testcases/general/omitted_parameter_type.dart.textual_outline.expect

@@ -0,0 +1,33 @@
+typedef void Typedef1(a, {b});
+
+method0(a, {b = 0}) {}
+
+class SuperClass {
+  void method(void f(a, {b})) {}
+  void method1(int a, {int? b}) {}
+}
+
+class SubClass extends SuperClass {
+  SubClass();
+  SubClass.constructor1(a, {b = 0}) {}
+  SubClass.constructor2(int x, String y, int z, String w);
+  SubClass.constructor3(a, {b = 0}) : this.constructor2(a, a, b, b);
+  factory SubClass.constructor4(a, {b = 0}) {}
+  method1(a, {b}) {}
+  method2(a, {b = 0}) {}
+  static method3(a, {b = 0}) {}
+}
+
+extension on int {
+  method1(a, {b = 0}) {}
+  static method2(a, {b = 0}) {}
+}
+
+extension type SuperExtensionType(int i) {
+  void method3(int a, {int? b}) {}
+}
+
+extension type SubExtensionType(int i) implements SuperExtensionType {
+  method3(a, {b}) {}
+  method4(a, {b = 0}) {}
+}

pkg/front_end/testcases/general/omitted_parameter_type.dart.textual_outline_modelled.expect

@@ -0,0 +1,33 @@
+class SubClass extends SuperClass {
+  SubClass();
+  SubClass.constructor1(a, {b = 0}) {}
+  SubClass.constructor2(int x, String y, int z, String w);
+  SubClass.constructor3(a, {b = 0}) : this.constructor2(a, a, b, b);
+  factory SubClass.constructor4(a, {b = 0}) {}
+  method1(a, {b}) {}
+  method2(a, {b = 0}) {}
+  static method3(a, {b = 0}) {}
+}
+
+class SuperClass {
+  void method(void f(a, {b})) {}
+  void method1(int a, {int? b}) {}
+}
+
+extension on int {
+  method1(a, {b = 0}) {}
+  static method2(a, {b = 0}) {}
+}
+
+extension type SubExtensionType(int i) implements SuperExtensionType {
+  method3(a, {b}) {}
+  method4(a, {b = 0}) {}
+}
+
+extension type SuperExtensionType(int i) {
+  void method3(int a, {int? b}) {}
+}
+
+method0(a, {b = 0}) {}
+
+typedef void Typedef1(a, {b});

pkg/front_end/testcases/primary_constructors/extension_type_errors.dart.strong.expect

@@ -71,7 +71,7 @@ import self as self;
 import "dart:core" as core;
 
 extension type ET0(dynamic a) {
-  abstract extension-type-member representation-field get a() → dynamic;
+  abstract extension-type-member representation-field get a() → core::Object?;
   constructor • = self::ET0|constructor#;
   constructor tearoff • = self::ET0|constructor#_#new#tearOff;
 }
@@ -151,11 +151,11 @@ extension type ET14(invalid-type #) {
   constructor • = self::ET14|constructor#;
   constructor tearoff • = self::ET14|constructor#_#new#tearOff;
 }
-static extension-type-member method ET0|constructor#(dynamic a) → self::ET0% /* erasure=dynamic, declared=! */ {
+static extension-type-member method ET0|constructor#(core::Object? a) → self::ET0% /* erasure=dynamic, declared=! */ {
   lowered final self::ET0% /* erasure=dynamic, declared=! */ #this = a;
   return #this;
 }
-static extension-type-member synthetic method ET0|constructor#_#new#tearOff(dynamic a) → self::ET0% /* erasure=dynamic, declared=! */
+static extension-type-member synthetic method ET0|constructor#_#new#tearOff(core::Object? a) → self::ET0% /* erasure=dynamic, declared=! */
   return self::ET0|constructor#(a);
 static extension-type-member method ET1|constructor#(core::bool a) → self::ET1% /* erasure=core::bool, declared=! */ {
   lowered final self::ET1% /* erasure=core::bool, declared=! */ #this = a;

pkg/front_end/testcases/primary_constructors/extension_type_errors.dart.strong.modular.expect

@@ -71,7 +71,7 @@ import self as self;
 import "dart:core" as core;
 
 extension type ET0(dynamic a) {
-  abstract extension-type-member representation-field get a() → dynamic;
+  abstract extension-type-member representation-field get a() → core::Object?;
   constructor • = self::ET0|constructor#;
   constructor tearoff • = self::ET0|constructor#_#new#tearOff;
 }
@@ -151,11 +151,11 @@ extension type ET14(invalid-type #) {
   constructor • = self::ET14|constructor#;
   constructor tearoff • = self::ET14|constructor#_#new#tearOff;
 }
-static extension-type-member method ET0|constructor#(dynamic a) → self::ET0% /* erasure=dynamic, declared=! */ {
+static extension-type-member method ET0|constructor#(core::Object? a) → self::ET0% /* erasure=dynamic, declared=! */ {
   lowered final self::ET0% /* erasure=dynamic, declared=! */ #this = a;
   return #this;
 }
-static extension-type-member synthetic method ET0|constructor#_#new#tearOff(dynamic a) → self::ET0% /* erasure=dynamic, declared=! */
+static extension-type-member synthetic method ET0|constructor#_#new#tearOff(core::Object? a) → self::ET0% /* erasure=dynamic, declared=! */
   return self::ET0|constructor#(a);
 static extension-type-member method ET1|constructor#(core::bool a) → self::ET1% /* erasure=core::bool, declared=! */ {
   lowered final self::ET1% /* erasure=core::bool, declared=! */ #this = a;

pkg/front_end/testcases/primary_constructors/extension_type_errors.dart.strong.outline.expect

@@ -71,7 +71,7 @@ import self as self;
 import "dart:core" as core;
 
 extension type ET0(dynamic a) {
-  abstract extension-type-member representation-field get a() → dynamic;
+  abstract extension-type-member representation-field get a() → core::Object?;
   constructor • = self::ET0|constructor#;
   constructor tearoff • = self::ET0|constructor#_#new#tearOff;
 }
@@ -151,9 +151,9 @@ extension type ET14(invalid-type #) {
   constructor • = self::ET14|constructor#;
   constructor tearoff • = self::ET14|constructor#_#new#tearOff;
 }
-static extension-type-member method ET0|constructor#(dynamic a) → self::ET0% /* erasure=dynamic, declared=! */
+static extension-type-member method ET0|constructor#(core::Object? a) → self::ET0% /* erasure=dynamic, declared=! */
   ;
-static extension-type-member synthetic method ET0|constructor#_#new#tearOff(dynamic a) → self::ET0% /* erasure=dynamic, declared=! */
+static extension-type-member synthetic method ET0|constructor#_#new#tearOff(core::Object? a) → self::ET0% /* erasure=dynamic, declared=! */
   return self::ET0|constructor#(a);
 static extension-type-member method ET1|constructor#(core::bool a) → self::ET1% /* erasure=core::bool, declared=! */
   ;

pkg/front_end/testcases/primary_constructors/extension_type_errors.dart.strong.transformed.expect

@@ -71,7 +71,7 @@ import self as self;
 import "dart:core" as core;
 
 extension type ET0(dynamic a) {
-  abstract extension-type-member representation-field get a() → dynamic;
+  abstract extension-type-member representation-field get a() → core::Object?;
   constructor • = self::ET0|constructor#;
   constructor tearoff • = self::ET0|constructor#_#new#tearOff;
 }
@@ -151,11 +151,11 @@ extension type ET14(invalid-type #) {
   constructor • = self::ET14|constructor#;
   constructor tearoff • = self::ET14|constructor#_#new#tearOff;
 }
-static extension-type-member method ET0|constructor#(dynamic a) → self::ET0% /* erasure=dynamic, declared=! */ {
+static extension-type-member method ET0|constructor#(core::Object? a) → self::ET0% /* erasure=dynamic, declared=! */ {
   lowered final self::ET0% /* erasure=dynamic, declared=! */ #this = a;
   return #this;
 }
-static extension-type-member synthetic method ET0|constructor#_#new#tearOff(dynamic a) → self::ET0% /* erasure=dynamic, declared=! */
+static extension-type-member synthetic method ET0|constructor#_#new#tearOff(core::Object? a) → self::ET0% /* erasure=dynamic, declared=! */
   return self::ET0|constructor#(a);
 static extension-type-member method ET1|constructor#(core::bool a) → self::ET1% /* erasure=core::bool, declared=! */ {
   lowered final self::ET1% /* erasure=core::bool, declared=! */ #this = a;

pkg/front_end/testcases/primary_constructors/inferred_type.dart

@@ -0,0 +1,39 @@
+// Copyright (c) 2026, 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.
+
+class C1(a, var b, final c) {
+  int d = a; // Error
+  int e = b; // Error
+  int f = c; // Error
+}
+
+class C2([a = null, var b = null, final c = null]) {
+  int d = a; // Error
+  int e = b; // Error
+  int f = c; // Error
+}
+
+class C3({a = null, var b = null, final c = null}) {
+  int d = a; // Error
+  int e = b; // Error
+  int f = c; // Error
+}
+
+extension type ET1(a);
+
+extension type ET2([a = null]);
+
+extension type ET3({a = null});
+
+test(C1 c1, C2 c2, C3 c3, ET1 e1, ET2 e2, ET3 e3) {
+  int a = c1.b; // Error
+  int b = c1.c; // Error
+  int c = c2.b; // Error
+  int d = c2.c; // Error
+  int e = c3.b; // Error
+  int f = c3.c; // Error
+  int g = e1.a; // Error
+  int h = e2.a; // Error
+  int i = e3.a; // Error
+}

pkg/front_end/testcases/primary_constructors/inferred_type.dart.strong.expect

@@ -0,0 +1,229 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:6:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int d = a; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:7:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int e = b; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:8:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int f = c; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:12:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int d = a; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:13:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int e = b; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:14:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int f = c; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:18:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int d = a; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:19:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int e = b; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:20:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int f = c; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:30:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int a = c1.b; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:31:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int b = c1.c; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:32:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int c = c2.b; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:33:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int d = c2.c; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:34:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int e = c3.b; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:35:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int f = c3.c; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:36:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int g = e1.a; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:37:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int h = e2.a; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:38:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int i = e3.a; // Error
+//              ^
+//
+import self as self;
+import "dart:core" as core;
+
+class C1 extends core::Object {
+  field core::Object? b;
+  final field core::Object? c;
+  field core::int d;
+  field core::int e;
+  field core::int f;
+  constructor •(core::Object? a, core::Object? b, final core::Object? c) → self::C1
+    : self::C1::d = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:6:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int d = a; // Error
+          ^" in a as{TypeError} core::int, self::C1::e = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:7:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int e = b; // Error
+          ^" in b as{TypeError} core::int, self::C1::f = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:8:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int f = c; // Error
+          ^" in c as{TypeError} core::int, self::C1::b = b, self::C1::c = c, super core::Object::•()
+    ;
+}
+class C2 extends core::Object {
+  field core::Object? b;
+  final field core::Object? c;
+  field core::int d;
+  field core::int e;
+  field core::int f;
+  constructor •([has-declared-initializer core::Object? a = #C1, has-declared-initializer core::Object? b = #C1, final has-declared-initializer core::Object? c = #C1]) → self::C2
+    : self::C2::d = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:12:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int d = a; // Error
+          ^" in a as{TypeError} core::int, self::C2::e = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:13:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int e = b; // Error
+          ^" in b as{TypeError} core::int, self::C2::f = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:14:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int f = c; // Error
+          ^" in c as{TypeError} core::int, self::C2::b = b, self::C2::c = c, super core::Object::•()
+    ;
+}
+class C3 extends core::Object {
+  field core::Object? b;
+  final field core::Object? c;
+  field core::int d;
+  field core::int e;
+  field core::int f;
+  constructor •({has-declared-initializer core::Object? a = #C1, has-declared-initializer core::Object? b = #C1, final has-declared-initializer core::Object? c = #C1}) → self::C3
+    : self::C3::d = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:18:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int d = a; // Error
+          ^" in a as{TypeError} core::int, self::C3::e = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:19:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int e = b; // Error
+          ^" in b as{TypeError} core::int, self::C3::f = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:20:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int f = c; // Error
+          ^" in c as{TypeError} core::int, self::C3::b = b, self::C3::c = c, super core::Object::•()
+    ;
+}
+extension type ET1(dynamic a) {
+  abstract extension-type-member representation-field get a() → core::Object?;
+  constructor • = self::ET1|constructor#;
+  constructor tearoff • = self::ET1|constructor#_#new#tearOff;
+}
+extension type ET2(dynamic a) {
+  abstract extension-type-member representation-field get a() → core::Object?;
+  constructor • = self::ET2|constructor#;
+  constructor tearoff • = self::ET2|constructor#_#new#tearOff;
+}
+extension type ET3(dynamic a) {
+  abstract extension-type-member representation-field get a() → core::Object?;
+  constructor • = self::ET3|constructor#;
+  constructor tearoff • = self::ET3|constructor#_#new#tearOff;
+}
+static extension-type-member method ET1|constructor#(core::Object? a) → self::ET1% /* erasure=dynamic, declared=! */ {
+  lowered final self::ET1% /* erasure=dynamic, declared=! */ #this = a;
+  return #this;
+}
+static extension-type-member synthetic method ET1|constructor#_#new#tearOff(core::Object? a) → self::ET1% /* erasure=dynamic, declared=! */
+  return self::ET1|constructor#(a);
+static extension-type-member method ET2|constructor#([has-declared-initializer core::Object? a = #C1]) → self::ET2% /* erasure=dynamic, declared=! */ {
+  lowered final self::ET2% /* erasure=dynamic, declared=! */ #this = a;
+  return #this;
+}
+static extension-type-member synthetic method ET2|constructor#_#new#tearOff([has-declared-initializer core::Object? a = #C1]) → self::ET2% /* erasure=dynamic, declared=! */
+  return self::ET2|constructor#(a);
+static extension-type-member method ET3|constructor#({has-declared-initializer core::Object? a = #C1}) → self::ET3% /* erasure=dynamic, declared=! */ {
+  lowered final self::ET3% /* erasure=dynamic, declared=! */ #this = a;
+  return #this;
+}
+static extension-type-member synthetic method ET3|constructor#_#new#tearOff({has-declared-initializer core::Object? a = #C1}) → self::ET3% /* erasure=dynamic, declared=! */
+  return self::ET3|constructor#(a: a);
+static method test(self::C1 c1, self::C2 c2, self::C3 c3, self::ET1% /* erasure=dynamic, declared=! */ e1, self::ET2% /* erasure=dynamic, declared=! */ e2, self::ET3% /* erasure=dynamic, declared=! */ e3) → dynamic {
+  core::int a = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:30:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int a = c1.b; // Error
+             ^" in c1.{self::C1::b}{core::Object?} as{TypeError} core::int;
+  core::int b = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:31:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int b = c1.c; // Error
+             ^" in c1.{self::C1::c}{core::Object?} as{TypeError} core::int;
+  core::int c = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:32:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int c = c2.b; // Error
+             ^" in c2.{self::C2::b}{core::Object?} as{TypeError} core::int;
+  core::int d = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:33:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int d = c2.c; // Error
+             ^" in c2.{self::C2::c}{core::Object?} as{TypeError} core::int;
+  core::int e = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:34:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int e = c3.b; // Error
+             ^" in c3.{self::C3::b}{core::Object?} as{TypeError} core::int;
+  core::int f = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:35:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int f = c3.c; // Error
+             ^" in c3.{self::C3::c}{core::Object?} as{TypeError} core::int;
+  core::int g = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:36:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int g = e1.a; // Error
+             ^" in (e1 as{Unchecked} core::Object?) as{TypeError} core::int;
+  core::int h = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:37:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int h = e2.a; // Error
+             ^" in (e2 as{Unchecked} core::Object?) as{TypeError} core::int;
+  core::int i = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:38:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int i = e3.a; // Error
+             ^" in (e3 as{Unchecked} core::Object?) as{TypeError} core::int;
+}
+
+constants  {
+  #C1 = null
+}

pkg/front_end/testcases/primary_constructors/inferred_type.dart.strong.modular.expect

@@ -0,0 +1,229 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:6:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int d = a; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:7:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int e = b; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:8:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int f = c; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:12:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int d = a; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:13:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int e = b; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:14:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int f = c; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:18:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int d = a; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:19:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int e = b; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:20:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int f = c; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:30:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int a = c1.b; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:31:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int b = c1.c; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:32:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int c = c2.b; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:33:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int d = c2.c; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:34:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int e = c3.b; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:35:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int f = c3.c; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:36:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int g = e1.a; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:37:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int h = e2.a; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:38:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int i = e3.a; // Error
+//              ^
+//
+import self as self;
+import "dart:core" as core;
+
+class C1 extends core::Object {
+  field core::Object? b;
+  final field core::Object? c;
+  field core::int d;
+  field core::int e;
+  field core::int f;
+  constructor •(core::Object? a, core::Object? b, final core::Object? c) → self::C1
+    : self::C1::d = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:6:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int d = a; // Error
+          ^" in a as{TypeError} core::int, self::C1::e = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:7:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int e = b; // Error
+          ^" in b as{TypeError} core::int, self::C1::f = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:8:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int f = c; // Error
+          ^" in c as{TypeError} core::int, self::C1::b = b, self::C1::c = c, super core::Object::•()
+    ;
+}
+class C2 extends core::Object {
+  field core::Object? b;
+  final field core::Object? c;
+  field core::int d;
+  field core::int e;
+  field core::int f;
+  constructor •([has-declared-initializer core::Object? a = #C1, has-declared-initializer core::Object? b = #C1, final has-declared-initializer core::Object? c = #C1]) → self::C2
+    : self::C2::d = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:12:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int d = a; // Error
+          ^" in a as{TypeError} core::int, self::C2::e = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:13:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int e = b; // Error
+          ^" in b as{TypeError} core::int, self::C2::f = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:14:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int f = c; // Error
+          ^" in c as{TypeError} core::int, self::C2::b = b, self::C2::c = c, super core::Object::•()
+    ;
+}
+class C3 extends core::Object {
+  field core::Object? b;
+  final field core::Object? c;
+  field core::int d;
+  field core::int e;
+  field core::int f;
+  constructor •({has-declared-initializer core::Object? a = #C1, has-declared-initializer core::Object? b = #C1, final has-declared-initializer core::Object? c = #C1}) → self::C3
+    : self::C3::d = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:18:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int d = a; // Error
+          ^" in a as{TypeError} core::int, self::C3::e = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:19:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int e = b; // Error
+          ^" in b as{TypeError} core::int, self::C3::f = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:20:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int f = c; // Error
+          ^" in c as{TypeError} core::int, self::C3::b = b, self::C3::c = c, super core::Object::•()
+    ;
+}
+extension type ET1(dynamic a) {
+  abstract extension-type-member representation-field get a() → core::Object?;
+  constructor • = self::ET1|constructor#;
+  constructor tearoff • = self::ET1|constructor#_#new#tearOff;
+}
+extension type ET2(dynamic a) {
+  abstract extension-type-member representation-field get a() → core::Object?;
+  constructor • = self::ET2|constructor#;
+  constructor tearoff • = self::ET2|constructor#_#new#tearOff;
+}
+extension type ET3(dynamic a) {
+  abstract extension-type-member representation-field get a() → core::Object?;
+  constructor • = self::ET3|constructor#;
+  constructor tearoff • = self::ET3|constructor#_#new#tearOff;
+}
+static extension-type-member method ET1|constructor#(core::Object? a) → self::ET1% /* erasure=dynamic, declared=! */ {
+  lowered final self::ET1% /* erasure=dynamic, declared=! */ #this = a;
+  return #this;
+}
+static extension-type-member synthetic method ET1|constructor#_#new#tearOff(core::Object? a) → self::ET1% /* erasure=dynamic, declared=! */
+  return self::ET1|constructor#(a);
+static extension-type-member method ET2|constructor#([has-declared-initializer core::Object? a = #C1]) → self::ET2% /* erasure=dynamic, declared=! */ {
+  lowered final self::ET2% /* erasure=dynamic, declared=! */ #this = a;
+  return #this;
+}
+static extension-type-member synthetic method ET2|constructor#_#new#tearOff([has-declared-initializer core::Object? a = #C1]) → self::ET2% /* erasure=dynamic, declared=! */
+  return self::ET2|constructor#(a);
+static extension-type-member method ET3|constructor#({has-declared-initializer core::Object? a = #C1}) → self::ET3% /* erasure=dynamic, declared=! */ {
+  lowered final self::ET3% /* erasure=dynamic, declared=! */ #this = a;
+  return #this;
+}
+static extension-type-member synthetic method ET3|constructor#_#new#tearOff({has-declared-initializer core::Object? a = #C1}) → self::ET3% /* erasure=dynamic, declared=! */
+  return self::ET3|constructor#(a: a);
+static method test(self::C1 c1, self::C2 c2, self::C3 c3, self::ET1% /* erasure=dynamic, declared=! */ e1, self::ET2% /* erasure=dynamic, declared=! */ e2, self::ET3% /* erasure=dynamic, declared=! */ e3) → dynamic {
+  core::int a = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:30:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int a = c1.b; // Error
+             ^" in c1.{self::C1::b}{core::Object?} as{TypeError} core::int;
+  core::int b = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:31:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int b = c1.c; // Error
+             ^" in c1.{self::C1::c}{core::Object?} as{TypeError} core::int;
+  core::int c = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:32:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int c = c2.b; // Error
+             ^" in c2.{self::C2::b}{core::Object?} as{TypeError} core::int;
+  core::int d = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:33:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int d = c2.c; // Error
+             ^" in c2.{self::C2::c}{core::Object?} as{TypeError} core::int;
+  core::int e = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:34:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int e = c3.b; // Error
+             ^" in c3.{self::C3::b}{core::Object?} as{TypeError} core::int;
+  core::int f = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:35:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int f = c3.c; // Error
+             ^" in c3.{self::C3::c}{core::Object?} as{TypeError} core::int;
+  core::int g = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:36:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int g = e1.a; // Error
+             ^" in (e1 as{Unchecked} core::Object?) as{TypeError} core::int;
+  core::int h = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:37:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int h = e2.a; // Error
+             ^" in (e2 as{Unchecked} core::Object?) as{TypeError} core::int;
+  core::int i = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:38:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int i = e3.a; // Error
+             ^" in (e3 as{Unchecked} core::Object?) as{TypeError} core::int;
+}
+
+constants  {
+  #C1 = null
+}

pkg/front_end/testcases/primary_constructors/inferred_type.dart.strong.outline.expect

@@ -0,0 +1,60 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+class C1 extends core::Object {
+  field core::Object? b;
+  final field core::Object? c;
+  field core::int d;
+  field core::int e;
+  field core::int f;
+  constructor •(core::Object? a, core::Object? b, final core::Object? c) → self::C1
+    ;
+}
+class C2 extends core::Object {
+  field core::Object? b;
+  final field core::Object? c;
+  field core::int d;
+  field core::int e;
+  field core::int f;
+  constructor •([has-declared-initializer core::Object? a = null, has-declared-initializer core::Object? b = null, final has-declared-initializer core::Object? c = null]) → self::C2
+    ;
+}
+class C3 extends core::Object {
+  field core::Object? b;
+  final field core::Object? c;
+  field core::int d;
+  field core::int e;
+  field core::int f;
+  constructor •({has-declared-initializer core::Object? a = null, has-declared-initializer core::Object? b = null, final has-declared-initializer core::Object? c = null}) → self::C3
+    ;
+}
+extension type ET1(dynamic a) {
+  abstract extension-type-member representation-field get a() → core::Object?;
+  constructor • = self::ET1|constructor#;
+  constructor tearoff • = self::ET1|constructor#_#new#tearOff;
+}
+extension type ET2(dynamic a) {
+  abstract extension-type-member representation-field get a() → core::Object?;
+  constructor • = self::ET2|constructor#;
+  constructor tearoff • = self::ET2|constructor#_#new#tearOff;
+}
+extension type ET3(dynamic a) {
+  abstract extension-type-member representation-field get a() → core::Object?;
+  constructor • = self::ET3|constructor#;
+  constructor tearoff • = self::ET3|constructor#_#new#tearOff;
+}
+static extension-type-member method ET1|constructor#(core::Object? a) → self::ET1% /* erasure=dynamic, declared=! */
+  ;
+static extension-type-member synthetic method ET1|constructor#_#new#tearOff(core::Object? a) → self::ET1% /* erasure=dynamic, declared=! */
+  return self::ET1|constructor#(a);
+static extension-type-member method ET2|constructor#([has-declared-initializer core::Object? a = null]) → self::ET2% /* erasure=dynamic, declared=! */
+  ;
+static extension-type-member synthetic method ET2|constructor#_#new#tearOff([has-declared-initializer core::Object? a]) → self::ET2% /* erasure=dynamic, declared=! */
+  return self::ET2|constructor#(a);
+static extension-type-member method ET3|constructor#({has-declared-initializer core::Object? a = null}) → self::ET3% /* erasure=dynamic, declared=! */
+  ;
+static extension-type-member synthetic method ET3|constructor#_#new#tearOff({has-declared-initializer core::Object? a}) → self::ET3% /* erasure=dynamic, declared=! */
+  return self::ET3|constructor#(a: a);
+static method test(self::C1 c1, self::C2 c2, self::C3 c3, self::ET1% /* erasure=dynamic, declared=! */ e1, self::ET2% /* erasure=dynamic, declared=! */ e2, self::ET3% /* erasure=dynamic, declared=! */ e3) → dynamic
+  ;

pkg/front_end/testcases/primary_constructors/inferred_type.dart.strong.transformed.expect

@@ -0,0 +1,229 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:6:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int d = a; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:7:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int e = b; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:8:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int f = c; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:12:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int d = a; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:13:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int e = b; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:14:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int f = c; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:18:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int d = a; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:19:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int e = b; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:20:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int f = c; // Error
+//           ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:30:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int a = c1.b; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:31:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int b = c1.c; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:32:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int c = c2.b; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:33:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int d = c2.c; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:34:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int e = c3.b; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:35:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int f = c3.c; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:36:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int g = e1.a; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:37:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int h = e2.a; // Error
+//              ^
+//
+// pkg/front_end/testcases/primary_constructors/inferred_type.dart:38:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+//  - 'Object' is from 'dart:core'.
+//   int i = e3.a; // Error
+//              ^
+//
+import self as self;
+import "dart:core" as core;
+
+class C1 extends core::Object {
+  field core::Object? b;
+  final field core::Object? c;
+  field core::int d;
+  field core::int e;
+  field core::int f;
+  constructor •(core::Object? a, core::Object? b, final core::Object? c) → self::C1
+    : self::C1::d = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:6:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int d = a; // Error
+          ^" in a as{TypeError} core::int, self::C1::e = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:7:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int e = b; // Error
+          ^" in b as{TypeError} core::int, self::C1::f = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:8:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int f = c; // Error
+          ^" in c as{TypeError} core::int, self::C1::b = b, self::C1::c = c, super core::Object::•()
+    ;
+}
+class C2 extends core::Object {
+  field core::Object? b;
+  final field core::Object? c;
+  field core::int d;
+  field core::int e;
+  field core::int f;
+  constructor •([has-declared-initializer core::Object? a = #C1, has-declared-initializer core::Object? b = #C1, final has-declared-initializer core::Object? c = #C1]) → self::C2
+    : self::C2::d = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:12:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int d = a; // Error
+          ^" in a as{TypeError} core::int, self::C2::e = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:13:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int e = b; // Error
+          ^" in b as{TypeError} core::int, self::C2::f = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:14:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int f = c; // Error
+          ^" in c as{TypeError} core::int, self::C2::b = b, self::C2::c = c, super core::Object::•()
+    ;
+}
+class C3 extends core::Object {
+  field core::Object? b;
+  final field core::Object? c;
+  field core::int d;
+  field core::int e;
+  field core::int f;
+  constructor •({has-declared-initializer core::Object? a = #C1, has-declared-initializer core::Object? b = #C1, final has-declared-initializer core::Object? c = #C1}) → self::C3
+    : self::C3::d = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:18:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int d = a; // Error
+          ^" in a as{TypeError} core::int, self::C3::e = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:19:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int e = b; // Error
+          ^" in b as{TypeError} core::int, self::C3::f = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:20:11: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int f = c; // Error
+          ^" in c as{TypeError} core::int, self::C3::b = b, self::C3::c = c, super core::Object::•()
+    ;
+}
+extension type ET1(dynamic a) {
+  abstract extension-type-member representation-field get a() → core::Object?;
+  constructor • = self::ET1|constructor#;
+  constructor tearoff • = self::ET1|constructor#_#new#tearOff;
+}
+extension type ET2(dynamic a) {
+  abstract extension-type-member representation-field get a() → core::Object?;
+  constructor • = self::ET2|constructor#;
+  constructor tearoff • = self::ET2|constructor#_#new#tearOff;
+}
+extension type ET3(dynamic a) {
+  abstract extension-type-member representation-field get a() → core::Object?;
+  constructor • = self::ET3|constructor#;
+  constructor tearoff • = self::ET3|constructor#_#new#tearOff;
+}
+static extension-type-member method ET1|constructor#(core::Object? a) → self::ET1% /* erasure=dynamic, declared=! */ {
+  lowered final self::ET1% /* erasure=dynamic, declared=! */ #this = a;
+  return #this;
+}
+static extension-type-member synthetic method ET1|constructor#_#new#tearOff(core::Object? a) → self::ET1% /* erasure=dynamic, declared=! */
+  return self::ET1|constructor#(a);
+static extension-type-member method ET2|constructor#([has-declared-initializer core::Object? a = #C1]) → self::ET2% /* erasure=dynamic, declared=! */ {
+  lowered final self::ET2% /* erasure=dynamic, declared=! */ #this = a;
+  return #this;
+}
+static extension-type-member synthetic method ET2|constructor#_#new#tearOff([has-declared-initializer core::Object? a = #C1]) → self::ET2% /* erasure=dynamic, declared=! */
+  return self::ET2|constructor#(a);
+static extension-type-member method ET3|constructor#({has-declared-initializer core::Object? a = #C1}) → self::ET3% /* erasure=dynamic, declared=! */ {
+  lowered final self::ET3% /* erasure=dynamic, declared=! */ #this = a;
+  return #this;
+}
+static extension-type-member synthetic method ET3|constructor#_#new#tearOff({has-declared-initializer core::Object? a = #C1}) → self::ET3% /* erasure=dynamic, declared=! */
+  return self::ET3|constructor#(a: a);
+static method test(self::C1 c1, self::C2 c2, self::C3 c3, self::ET1% /* erasure=dynamic, declared=! */ e1, self::ET2% /* erasure=dynamic, declared=! */ e2, self::ET3% /* erasure=dynamic, declared=! */ e3) → dynamic {
+  core::int a = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:30:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int a = c1.b; // Error
+             ^" in c1.{self::C1::b}{core::Object?} as{TypeError} core::int;
+  core::int b = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:31:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int b = c1.c; // Error
+             ^" in c1.{self::C1::c}{core::Object?} as{TypeError} core::int;
+  core::int c = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:32:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int c = c2.b; // Error
+             ^" in c2.{self::C2::b}{core::Object?} as{TypeError} core::int;
+  core::int d = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:33:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int d = c2.c; // Error
+             ^" in c2.{self::C2::c}{core::Object?} as{TypeError} core::int;
+  core::int e = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:34:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int e = c3.b; // Error
+             ^" in c3.{self::C3::b}{core::Object?} as{TypeError} core::int;
+  core::int f = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:35:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int f = c3.c; // Error
+             ^" in c3.{self::C3::c}{core::Object?} as{TypeError} core::int;
+  core::int g = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:36:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int g = e1.a; // Error
+             ^" in (e1 as{Unchecked} core::Object?) as{TypeError} core::int;
+  core::int h = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:37:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int h = e2.a; // Error
+             ^" in (e2 as{Unchecked} core::Object?) as{TypeError} core::int;
+  core::int i = invalid-expression "pkg/front_end/testcases/primary_constructors/inferred_type.dart:38:14: Error: A value of type 'Object?' can't be assigned to a variable of type 'int'.
+ - 'Object' is from 'dart:core'.
+  int i = e3.a; // Error
+             ^" in (e3 as{Unchecked} core::Object?) as{TypeError} core::int;
+}
+
+constants  {
+  #C1 = null
+}

pkg/front_end/testcases/primary_constructors/inferred_type.dart.textual_outline.expect

@@ -0,0 +1,25 @@
+class C1(a, var b, final c) {
+  int d = a;
+  int e = b;
+  int f = c;
+}
+
+class C2([a = null, var b = null, final c = null]) {
+  int d = a;
+  int e = b;
+  int f = c;
+}
+
+class C3({a = null, var b = null, final c = null}) {
+  int d = a;
+  int e = b;
+  int f = c;
+}
+
+extension type ET1(a);
+
+extension type ET2([a = null]);
+
+extension type ET3({a = null});
+
+test(C1 c1, C2 c2, C3 c3, ET1 e1, ET2 e2, ET3 e3) {}

pkg/front_end/testcases/primary_constructors/inferred_type.dart.textual_outline_modelled.expect

@@ -0,0 +1,25 @@
+class C1(a, var b, final c) {
+  int d = a;
+  int e = b;
+  int f = c;
+}
+
+class C2([a = null, var b = null, final c = null]) {
+  int d = a;
+  int e = b;
+  int f = c;
+}
+
+class C3({a = null, var b = null, final c = null}) {
+  int d = a;
+  int e = b;
+  int f = c;
+}
+
+extension type ET1(a);
+
+extension type ET2([a = null]);
+
+extension type ET3({a = null});
+
+test(C1 c1, C2 c2, C3 c3, ET1 e1, ET2 e2, ET3 e3) {}

pkg/front_end/testcases/primary_constructors/parameter_type_inference.dart.strong.expect

@@ -47,12 +47,12 @@ class C3 extends core::Object {
     ;
 }
 class C4 extends core::Object {
-  constructor •([dynamic e = #C1]) → self::C4
+  constructor •([core::Object? e = #C1]) → self::C4
     : super core::Object::•()
     ;
 }
 class C5 extends core::Object {
-  constructor •({dynamic f = #C2}) → self::C5
+  constructor •({core::Object? f = #C2}) → self::C5
     : super core::Object::•()
     ;
 }

pkg/front_end/testcases/primary_constructors/parameter_type_inference.dart.strong.modular.expect

@@ -47,12 +47,12 @@ class C3 extends core::Object {
     ;
 }
 class C4 extends core::Object {
-  constructor •([dynamic e = #C1]) → self::C4
+  constructor •([core::Object? e = #C1]) → self::C4
     : super core::Object::•()
     ;
 }
 class C5 extends core::Object {
-  constructor •({dynamic f = #C2}) → self::C5
+  constructor •({core::Object? f = #C2}) → self::C5
     : super core::Object::•()
     ;
 }

pkg/front_end/testcases/primary_constructors/parameter_type_inference.dart.strong.outline.expect

@@ -23,11 +23,11 @@ class C3 extends core::Object {
     ;
 }
 class C4 extends core::Object {
-  constructor •([dynamic e = 0]) → self::C4
+  constructor •([core::Object? e = 0]) → self::C4
     ;
 }
 class C5 extends core::Object {
-  constructor •({dynamic f = true}) → self::C5
+  constructor •({core::Object? f = true}) → self::C5
     ;
 }
 static method test() → dynamic

pkg/front_end/testcases/primary_constructors/parameter_type_inference.dart.strong.transformed.expect

@@ -47,12 +47,12 @@ class C3 extends core::Object {
     ;
 }
 class C4 extends core::Object {
-  constructor •([dynamic e = #C1]) → self::C4
+  constructor •([core::Object? e = #C1]) → self::C4
     : super core::Object::•()
     ;
 }
 class C5 extends core::Object {
-  constructor •({dynamic f = #C2}) → self::C5
+  constructor •({core::Object? f = #C2}) → self::C5
     : super core::Object::•()
     ;
 }

pkg/front_end/testcases/primary_constructors/representation_field_modifier.dart.strong.expect

@@ -29,17 +29,17 @@ extension type ET3(core::int i) {
   constructor tearoff • = self::ET3|constructor#_#new#tearOff;
 }
 extension type ET4(dynamic i) {
-  abstract extension-type-member representation-field get i() → dynamic;
+  abstract extension-type-member representation-field get i() → core::Object?;
   constructor • = self::ET4|constructor#;
   constructor tearoff • = self::ET4|constructor#_#new#tearOff;
 }
 extension type ET5(dynamic i) {
-  abstract extension-type-member representation-field get i() → dynamic;
+  abstract extension-type-member representation-field get i() → core::Object?;
   constructor • = self::ET5|constructor#;
   constructor tearoff • = self::ET5|constructor#_#new#tearOff;
 }
 extension type ET6(dynamic i) {
-  abstract extension-type-member representation-field get i() → dynamic;
+  abstract extension-type-member representation-field get i() → core::Object?;
   constructor • = self::ET6|constructor#;
   constructor tearoff • = self::ET6|constructor#_#new#tearOff;
 }
@@ -61,21 +61,21 @@ static extension-type-member method ET3|constructor#(final core::int i) → self
 }
 static extension-type-member synthetic method ET3|constructor#_#new#tearOff(core::int i) → self::ET3% /* erasure=core::int, declared=! */
   return self::ET3|constructor#(i);
-static extension-type-member method ET4|constructor#(dynamic i) → self::ET4% /* erasure=dynamic, declared=! */ {
+static extension-type-member method ET4|constructor#(core::Object? i) → self::ET4% /* erasure=dynamic, declared=! */ {
   lowered final self::ET4% /* erasure=dynamic, declared=! */ #this = i;
   return #this;
 }
-static extension-type-member synthetic method ET4|constructor#_#new#tearOff(dynamic i) → self::ET4% /* erasure=dynamic, declared=! */
+static extension-type-member synthetic method ET4|constructor#_#new#tearOff(core::Object? i) → self::ET4% /* erasure=dynamic, declared=! */
   return self::ET4|constructor#(i);
-static extension-type-member method ET5|constructor#(dynamic i) → self::ET5% /* erasure=dynamic, declared=! */ {
+static extension-type-member method ET5|constructor#(core::Object? i) → self::ET5% /* erasure=dynamic, declared=! */ {
   lowered final self::ET5% /* erasure=dynamic, declared=! */ #this = i;
   return #this;
 }
-static extension-type-member synthetic method ET5|constructor#_#new#tearOff(dynamic i) → self::ET5% /* erasure=dynamic, declared=! */
+static extension-type-member synthetic method ET5|constructor#_#new#tearOff(core::Object? i) → self::ET5% /* erasure=dynamic, declared=! */
   return self::ET5|constructor#(i);
-static extension-type-member method ET6|constructor#(final dynamic i) → self::ET6% /* erasure=dynamic, declared=! */ {
+static extension-type-member method ET6|constructor#(final core::Object? i) → self::ET6% /* erasure=dynamic, declared=! */ {
   lowered final self::ET6% /* erasure=dynamic, declared=! */ #this = i;
   return #this;
 }
-static extension-type-member synthetic method ET6|constructor#_#new#tearOff(dynamic i) → self::ET6% /* erasure=dynamic, declared=! */
+static extension-type-member synthetic method ET6|constructor#_#new#tearOff(core::Object? i) → self::ET6% /* erasure=dynamic, declared=! */
   return self::ET6|constructor#(i);

pkg/front_end/testcases/primary_constructors/representation_field_modifier.dart.strong.modular.expect

@@ -29,17 +29,17 @@ extension type ET3(core::int i) {
   constructor tearoff • = self::ET3|constructor#_#new#tearOff;
 }
 extension type ET4(dynamic i) {
-  abstract extension-type-member representation-field get i() → dynamic;
+  abstract extension-type-member representation-field get i() → core::Object?;
   constructor • = self::ET4|constructor#;
   constructor tearoff • = self::ET4|constructor#_#new#tearOff;
 }
 extension type ET5(dynamic i) {
-  abstract extension-type-member representation-field get i() → dynamic;
+  abstract extension-type-member representation-field get i() → core::Object?;
   constructor • = self::ET5|constructor#;
   constructor tearoff • = self::ET5|constructor#_#new#tearOff;
 }
 extension type ET6(dynamic i) {
-  abstract extension-type-member representation-field get i() → dynamic;
+  abstract extension-type-member representation-field get i() → core::Object?;
   constructor • = self::ET6|constructor#;
   constructor tearoff • = self::ET6|constructor#_#new#tearOff;
 }
@@ -61,21 +61,21 @@ static extension-type-member method ET3|constructor#(final core::int i) → self
 }
 static extension-type-member synthetic method ET3|constructor#_#new#tearOff(core::int i) → self::ET3% /* erasure=core::int, declared=! */
   return self::ET3|constructor#(i);
-static extension-type-member method ET4|constructor#(dynamic i) → self::ET4% /* erasure=dynamic, declared=! */ {
+static extension-type-member method ET4|constructor#(core::Object? i) → self::ET4% /* erasure=dynamic, declared=! */ {
   lowered final self::ET4% /* erasure=dynamic, declared=! */ #this = i;
   return #this;
 }
-static extension-type-member synthetic method ET4|constructor#_#new#tearOff(dynamic i) → self::ET4% /* erasure=dynamic, declared=! */
+static extension-type-member synthetic method ET4|constructor#_#new#tearOff(core::Object? i) → self::ET4% /* erasure=dynamic, declared=! */
   return self::ET4|constructor#(i);
-static extension-type-member method ET5|constructor#(dynamic i) → self::ET5% /* erasure=dynamic, declared=! */ {
+static extension-type-member method ET5|constructor#(core::Object? i) → self::ET5% /* erasure=dynamic, declared=! */ {
   lowered final self::ET5% /* erasure=dynamic, declared=! */ #this = i;
   return #this;
 }
-static extension-type-member synthetic method ET5|constructor#_#new#tearOff(dynamic i) → self::ET5% /* erasure=dynamic, declared=! */
+static extension-type-member synthetic method ET5|constructor#_#new#tearOff(core::Object? i) → self::ET5% /* erasure=dynamic, declared=! */
   return self::ET5|constructor#(i);
-static extension-type-member method ET6|constructor#(final dynamic i) → self::ET6% /* erasure=dynamic, declared=! */ {
+static extension-type-member method ET6|constructor#(final core::Object? i) → self::ET6% /* erasure=dynamic, declared=! */ {
   lowered final self::ET6% /* erasure=dynamic, declared=! */ #this = i;
   return #this;
 }
-static extension-type-member synthetic method ET6|constructor#_#new#tearOff(dynamic i) → self::ET6% /* erasure=dynamic, declared=! */
+static extension-type-member synthetic method ET6|constructor#_#new#tearOff(core::Object? i) → self::ET6% /* erasure=dynamic, declared=! */
   return self::ET6|constructor#(i);

pkg/front_end/testcases/primary_constructors/representation_field_modifier.dart.strong.outline.expect

@@ -29,17 +29,17 @@ extension type ET3(core::int i) {
   constructor tearoff • = self::ET3|constructor#_#new#tearOff;
 }
 extension type ET4(dynamic i) {
-  abstract extension-type-member representation-field get i() → dynamic;
+  abstract extension-type-member representation-field get i() → core::Object?;
   constructor • = self::ET4|constructor#;
   constructor tearoff • = self::ET4|constructor#_#new#tearOff;
 }
 extension type ET5(dynamic i) {
-  abstract extension-type-member representation-field get i() → dynamic;
+  abstract extension-type-member representation-field get i() → core::Object?;
   constructor • = self::ET5|constructor#;
   constructor tearoff • = self::ET5|constructor#_#new#tearOff;
 }
 extension type ET6(dynamic i) {
-  abstract extension-type-member representation-field get i() → dynamic;
+  abstract extension-type-member representation-field get i() → core::Object?;
   constructor • = self::ET6|constructor#;
   constructor tearoff • = self::ET6|constructor#_#new#tearOff;
 }
@@ -55,15 +55,15 @@ static extension-type-member method ET3|constructor#(final core::int i) → self
   ;
 static extension-type-member synthetic method ET3|constructor#_#new#tearOff(core::int i) → self::ET3% /* erasure=core::int, declared=! */
   return self::ET3|constructor#(i);
-static extension-type-member method ET4|constructor#(dynamic i) → self::ET4% /* erasure=dynamic, declared=! */
+static extension-type-member method ET4|constructor#(core::Object? i) → self::ET4% /* erasure=dynamic, declared=! */
   ;
-static extension-type-member synthetic method ET4|constructor#_#new#tearOff(dynamic i) → self::ET4% /* erasure=dynamic, declared=! */
+static extension-type-member synthetic method ET4|constructor#_#new#tearOff(core::Object? i) → self::ET4% /* erasure=dynamic, declared=! */
   return self::ET4|constructor#(i);
-static extension-type-member method ET5|constructor#(dynamic i) → self::ET5% /* erasure=dynamic, declared=! */
+static extension-type-member method ET5|constructor#(core::Object? i) → self::ET5% /* erasure=dynamic, declared=! */
   ;
-static extension-type-member synthetic method ET5|constructor#_#new#tearOff(dynamic i) → self::ET5% /* erasure=dynamic, declared=! */
+static extension-type-member synthetic method ET5|constructor#_#new#tearOff(core::Object? i) → self::ET5% /* erasure=dynamic, declared=! */
   return self::ET5|constructor#(i);
-static extension-type-member method ET6|constructor#(final dynamic i) → self::ET6% /* erasure=dynamic, declared=! */
+static extension-type-member method ET6|constructor#(final core::Object? i) → self::ET6% /* erasure=dynamic, declared=! */
   ;
-static extension-type-member synthetic method ET6|constructor#_#new#tearOff(dynamic i) → self::ET6% /* erasure=dynamic, declared=! */
+static extension-type-member synthetic method ET6|constructor#_#new#tearOff(core::Object? i) → self::ET6% /* erasure=dynamic, declared=! */
   return self::ET6|constructor#(i);

pkg/front_end/testcases/primary_constructors/representation_field_modifier.dart.strong.transformed.expect

@@ -29,17 +29,17 @@ extension type ET3(core::int i) {
   constructor tearoff • = self::ET3|constructor#_#new#tearOff;
 }
 extension type ET4(dynamic i) {
-  abstract extension-type-member representation-field get i() → dynamic;
+  abstract extension-type-member representation-field get i() → core::Object?;
   constructor • = self::ET4|constructor#;
   constructor tearoff • = self::ET4|constructor#_#new#tearOff;
 }
 extension type ET5(dynamic i) {
-  abstract extension-type-member representation-field get i() → dynamic;
+  abstract extension-type-member representation-field get i() → core::Object?;
   constructor • = self::ET5|constructor#;
   constructor tearoff • = self::ET5|constructor#_#new#tearOff;
 }
 extension type ET6(dynamic i) {
-  abstract extension-type-member representation-field get i() → dynamic;
+  abstract extension-type-member representation-field get i() → core::Object?;
   constructor • = self::ET6|constructor#;
   constructor tearoff • = self::ET6|constructor#_#new#tearOff;
 }
@@ -61,21 +61,21 @@ static extension-type-member method ET3|constructor#(final core::int i) → self
 }
 static extension-type-member synthetic method ET3|constructor#_#new#tearOff(core::int i) → self::ET3% /* erasure=core::int, declared=! */
   return self::ET3|constructor#(i);
-static extension-type-member method ET4|constructor#(dynamic i) → self::ET4% /* erasure=dynamic, declared=! */ {
+static extension-type-member method ET4|constructor#(core::Object? i) → self::ET4% /* erasure=dynamic, declared=! */ {
   lowered final self::ET4% /* erasure=dynamic, declared=! */ #this = i;
   return #this;
 }
-static extension-type-member synthetic method ET4|constructor#_#new#tearOff(dynamic i) → self::ET4% /* erasure=dynamic, declared=! */
+static extension-type-member synthetic method ET4|constructor#_#new#tearOff(core::Object? i) → self::ET4% /* erasure=dynamic, declared=! */
   return self::ET4|constructor#(i);
-static extension-type-member method ET5|constructor#(dynamic i) → self::ET5% /* erasure=dynamic, declared=! */ {
+static extension-type-member method ET5|constructor#(core::Object? i) → self::ET5% /* erasure=dynamic, declared=! */ {
   lowered final self::ET5% /* erasure=dynamic, declared=! */ #this = i;
   return #this;
 }
-static extension-type-member synthetic method ET5|constructor#_#new#tearOff(dynamic i) → self::ET5% /* erasure=dynamic, declared=! */
+static extension-type-member synthetic method ET5|constructor#_#new#tearOff(core::Object? i) → self::ET5% /* erasure=dynamic, declared=! */
   return self::ET5|constructor#(i);
-static extension-type-member method ET6|constructor#(final dynamic i) → self::ET6% /* erasure=dynamic, declared=! */ {
+static extension-type-member method ET6|constructor#(final core::Object? i) → self::ET6% /* erasure=dynamic, declared=! */ {
   lowered final self::ET6% /* erasure=dynamic, declared=! */ #this = i;
   return #this;
 }
-static extension-type-member synthetic method ET6|constructor#_#new#tearOff(dynamic i) → self::ET6% /* erasure=dynamic, declared=! */
+static extension-type-member synthetic method ET6|constructor#_#new#tearOff(core::Object? i) → self::ET6% /* erasure=dynamic, declared=! */
   return self::ET6|constructor#(i);