[cfe] Remove use of the AST-based class hierarchy from the inferrer

Change-Id: I636dd75b443a23dc531fbeddfbbf3cb76358e5f0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/269780
Reviewed-by: Chloe Stefantsova <cstefantsova@google.com>
Commit-Queue: Johnni Winther <johnniwinther@google.com>

pkg/front_end/lib/src/fasta/kernel/hierarchy/hierarchy_builder.dart

@@ -78,6 +78,7 @@ class ClassHierarchyBuilder implements ClassHierarchyBase {
 
   @override
   Supertype? getClassAsInstanceOf(Class subclass, Class superclass) {
+    if (identical(subclass, superclass)) return subclass.asThisSupertype;
     ClassHierarchyNode clsNode = getNodeFromClass(subclass);
     ClassHierarchyNode supertypeNode = getNodeFromClass(superclass);
     List<Supertype> superclasses = clsNode.superclasses;
@@ -114,6 +115,11 @@ class ClassHierarchyBuilder implements ClassHierarchyBase {
     return asSupertypeOf(type, superclass)?.typeArguments;
   }
 
+  @override
+  bool isSubtypeOf(Class subtype, Class superclass) {
+    return getClassAsInstanceOf(subtype, superclass) != null;
+  }
+
   @override
   InterfaceType getLegacyLeastUpperBound(
       InterfaceType type1, InterfaceType type2, Library clientLibrary) {

pkg/front_end/lib/src/fasta/kernel/hierarchy/members_builder.dart

@@ -148,6 +148,18 @@ class ClassMembersBuilder implements ClassHierarchyMembers {
     return getNodeFromClass(cls).getInterfaceMember(name, setter);
   }
 
+  @override
+  Member? getDispatchTarget(Class cls, Name name, {bool setter = false}) {
+    return getNodeFromClass(cls)
+        .getDispatchTarget(name, setter)
+        ?.getMember(this);
+  }
+
+  ClassMember? getDispatchClassMember(Class cls, Name name,
+      {bool setter = false}) {
+    return getNodeFromClass(cls).getDispatchTarget(name, setter);
+  }
+
   static ClassMembersBuilder build(
       ClassHierarchyBuilder hierarchyBuilder, List<ClassBuilder> classes) {
     ClassMembersBuilder membersBuilder =

pkg/front_end/lib/src/fasta/kernel/hierarchy/members_node.dart

@@ -74,14 +74,6 @@ class ClassMembersNodeBuilder {
   bool get shouldModifyKernel =>
       classBuilder.libraryBuilder.loader == hierarchy.loader;
 
-  ClassMember? checkInheritanceConflict(ClassMember a, ClassMember b) {
-    if (a.isStatic || a.isProperty != b.isProperty) {
-      reportInheritanceConflict(a, b);
-      return a;
-    }
-    return null;
-  }
-
   static void inferMethodType(
       ClassHierarchyBuilder hierarchyBuilder,
       ClassMembersBuilder membersBuilder,
@@ -2311,6 +2303,7 @@ class ClassMembersNodeBuilder {
 
     return new ClassMembersNode(
         classBuilder,
+        supernode,
         classMemberMap,
         classSetterMap,
         interfaceMemberMap,
@@ -2360,6 +2353,8 @@ class ClassMembersNodeBuilder {
 class ClassMembersNode {
   final ClassBuilder classBuilder;
 
+  final ClassMembersNode? supernode;
+
   /// All the members of this class including [classMembers] of its
   /// superclasses. The members are sorted by [compareDeclarations].
   final Map<Name, ClassMember> classMemberMap;
@@ -2387,6 +2382,7 @@ class ClassMembersNode {
 
   ClassMembersNode(
       this.classBuilder,
+      this.supernode,
       this.classMemberMap,
       this.classSetterMap,
       this.interfaceMemberMap,
@@ -2434,9 +2430,16 @@ class ClassMembersNode {
   }
 
   ClassMember? getInterfaceMember(Name name, bool isSetter) {
-    return isSetter
+    ClassMember? result = isSetter
         ? (interfaceSetterMap ?? classSetterMap)[name]
         : (interfaceMemberMap ?? classMemberMap)[name];
+    if (result == null) {
+      return null;
+    }
+    if (result.isStatic) {
+      return null;
+    }
+    return result;
   }
 
   ClassMember? findMember(Name name, List<ClassMember> declarations) {
@@ -2464,7 +2467,17 @@ class ClassMembersNode {
   }
 
   ClassMember? getDispatchTarget(Name name, bool isSetter) {
-    return isSetter ? classSetterMap[name] : classMemberMap[name];
+    ClassMember? result =
+        isSetter ? classSetterMap[name] : classMemberMap[name];
+    if (result == null) {
+      return null;
+    }
+    if (result.isStatic) {
+      // TODO(johnniwinther): Can we avoid putting static members in the
+      // [classMemberMap]/[classSetterMap] maps?
+      return supernode?.getDispatchTarget(name, isSetter);
+    }
+    return result;
   }
 }
 

pkg/front_end/lib/src/fasta/source/source_library_builder.dart

@@ -12,7 +12,8 @@ import 'package:_fe_analyzer_shared/src/scanner/token.dart' show Token;
 import 'package:_fe_analyzer_shared/src/util/resolve_relative_uri.dart'
     show resolveRelativeUri;
 import 'package:kernel/ast.dart' hide Combinator, MapLiteralEntry;
-import 'package:kernel/class_hierarchy.dart' show ClassHierarchy;
+import 'package:kernel/class_hierarchy.dart'
+    show ClassHierarchy, ClassHierarchyBase, ClassHierarchyMembers;
 import 'package:kernel/clone.dart' show CloneVisitorNotMembers;
 import 'package:kernel/reference_from_index.dart'
     show IndexedClass, IndexedContainer, IndexedLibrary;
@@ -4416,7 +4417,8 @@ class SourceLibraryBuilder extends LibraryBuilderImpl {
   void checkBoundsInMethodInvocation(
       DartType receiverType,
       TypeEnvironment typeEnvironment,
-      ClassHierarchy hierarchy,
+      ClassHierarchyBase classHierarchy,
+      ClassHierarchyMembers membersHierarchy,
       Name name,
       Member? interfaceTarget,
       Arguments arguments,
@@ -4437,14 +4439,14 @@ class SourceLibraryBuilder extends LibraryBuilderImpl {
     }
     // TODO(cstefantsova): Find a better way than relying on [interfaceTarget].
     Member? method =
-        hierarchy.getDispatchTarget(klass, name) ?? interfaceTarget;
+        membersHierarchy.getDispatchTarget(klass, name) ?? interfaceTarget;
     // ignore: unnecessary_null_comparison
     if (method == null || method is! Procedure) {
       return;
     }
     if (klass != method.enclosingClass) {
       Supertype parent =
-          hierarchy.getClassAsInstanceOf(klass, method.enclosingClass!)!;
+          classHierarchy.getClassAsInstanceOf(klass, method.enclosingClass!)!;
       klass = method.enclosingClass!;
       receiverTypeArguments = parent.typeArguments;
       Map<TypeParameter, DartType> instanceSubstitutionMap = substitutionMap;
@@ -4492,7 +4494,6 @@ class SourceLibraryBuilder extends LibraryBuilderImpl {
 
   void checkBoundsInFunctionInvocation(
       TypeEnvironment typeEnvironment,
-      ClassHierarchy hierarchy,
       FunctionType functionType,
       String? localName,
       Arguments arguments,
@@ -4526,7 +4527,6 @@ class SourceLibraryBuilder extends LibraryBuilderImpl {
 
   void checkBoundsInInstantiation(
       TypeEnvironment typeEnvironment,
-      ClassHierarchy hierarchy,
       FunctionType functionType,
       List<DartType> typeArguments,
       Uri fileUri,

pkg/front_end/lib/src/fasta/source/source_loader.dart

@@ -2295,21 +2295,25 @@ severity: $severity
           Name name = restrictedMemberNames[i];
           Class? declarer = restrictedMemberDeclarers[i];
 
-          Member? member = hierarchy.getDispatchTarget(classBuilder.cls, name);
-          if (member?.enclosingClass != declarer &&
-              member?.enclosingClass != classBuilder.cls &&
-              member?.isAbstract == false) {
-            classBuilder.libraryBuilder.addProblem(
-                templateEnumInheritsRestricted.withArguments(name.text),
-                classBuilder.charOffset,
-                classBuilder.name.length,
-                classBuilder.fileUri,
-                context: <LocatedMessage>[
-                  messageEnumInheritsRestrictedMember.withLocation(
-                      member!.fileUri,
-                      member.fileOffset,
-                      member.name.text.length)
-                ]);
+          ClassMember? classMember =
+              membersBuilder.getDispatchClassMember(classBuilder.cls, name);
+          if (classMember != null) {
+            Member member = classMember.getMember(membersBuilder);
+            if (member.enclosingClass != declarer &&
+                member.enclosingClass != classBuilder.cls &&
+                member.isAbstract == false) {
+              classBuilder.libraryBuilder.addProblem(
+                  templateEnumInheritsRestricted.withArguments(name.text),
+                  classBuilder.charOffset,
+                  classBuilder.name.length,
+                  classBuilder.fileUri,
+                  context: <LocatedMessage>[
+                    messageEnumInheritsRestrictedMember.withLocation(
+                        classMember.fileUri,
+                        classMember.charOffset,
+                        member.name.text.length)
+                  ]);
+            }
           }
         }
       }

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

@@ -1407,7 +1407,7 @@ class InferenceVisitorImpl extends InferenceVisitorBase
     if (inferredExpressionType is InterfaceType) {
       // TODO(johnniwinther): Should we use the type of
       //  `iterable.iterator.current` instead?
-      List<DartType>? supertypeArguments = classHierarchy
+      List<DartType>? supertypeArguments = hierarchyBuilder
           .getTypeArgumentsAsInstanceOf(inferredExpressionType, iterableClass);
       if (supertypeArguments != null) {
         inferredType = supertypeArguments[0];
@@ -1636,7 +1636,7 @@ class InferenceVisitorImpl extends InferenceVisitorBase
   InitializerInferenceResult visitInvalidSuperInitializerJudgment(
       InvalidSuperInitializerJudgment node) {
     Substitution substitution = Substitution.fromSupertype(
-        classHierarchy.getClassAsInstanceOf(
+        hierarchyBuilder.getClassAsInstanceOf(
             thisType!.classNode, node.target.enclosingClass)!);
     FunctionType functionType = replaceReturnType(
         substitution.substituteType(node.target.function
@@ -2843,10 +2843,10 @@ class InferenceVisitorImpl extends InferenceVisitorBase
     // Ambiguous set/map literal
     if (unfuturedTypeContext is InterfaceType) {
       typeContextIsMap = typeContextIsMap ||
-          classHierarchy.isSubtypeOf(
+          hierarchyBuilder.isSubtypeOf(
               unfuturedTypeContext.classNode, coreTypes.mapClass);
       typeContextIsIterable = typeContextIsIterable ||
-          classHierarchy.isSubtypeOf(
+          hierarchyBuilder.isSubtypeOf(
               unfuturedTypeContext.classNode, coreTypes.iterableClass);
       if (node.entries.isEmpty && typeContextIsIterable && !typeContextIsMap) {
         // Set literal
@@ -3086,7 +3086,7 @@ class InferenceVisitorImpl extends InferenceVisitorBase
           result.inferredType, result.applyResult(invocation));
     } else {
       // TODO(johnniwinther): Handle augmentation of field with inferred types.
-      TypeInferenceEngine.resolveInferenceNode(member, classHierarchy);
+      TypeInferenceEngine.resolveInferenceNode(member, hierarchyBuilder);
       Link<NullAwareGuard> nullAwareGuards = const Link<NullAwareGuard>();
       DartType receiverType = member.getterType;
       Expression receiver = new StaticGet(member)..fileOffset = node.fileOffset;
@@ -5892,7 +5892,7 @@ class InferenceVisitorImpl extends InferenceVisitorBase
       return new ExpressionInferenceResult(replacementType, replacement);
     } else {
       // TODO(johnniwinther): Handle augmentation of field with inferred types.
-      TypeInferenceEngine.resolveInferenceNode(member, classHierarchy);
+      TypeInferenceEngine.resolveInferenceNode(member, hierarchyBuilder);
       DartType writeContext = member.setterType;
       ExpressionInferenceResult rhsResult =
           inferExpression(node.value, writeContext, isVoidAllowed: true);
@@ -6153,7 +6153,7 @@ class InferenceVisitorImpl extends InferenceVisitorBase
           readResult.inferredType, readResult.expression);
     } else {
       // TODO(johnniwinther): Handle augmentation of field with inferred types.
-      TypeInferenceEngine.resolveInferenceNode(member, classHierarchy);
+      TypeInferenceEngine.resolveInferenceNode(member, hierarchyBuilder);
       DartType type = member.getterType;
 
       if (member is Procedure && member.kind == ProcedureKind.Method) {
@@ -6302,7 +6302,7 @@ class InferenceVisitorImpl extends InferenceVisitorBase
   ExpressionInferenceResult visitStaticSet(
       StaticSet node, DartType typeContext) {
     Member writeMember = node.target;
-    TypeInferenceEngine.resolveInferenceNode(writeMember, classHierarchy);
+    TypeInferenceEngine.resolveInferenceNode(writeMember, hierarchyBuilder);
     DartType writeContext = writeMember.setterType;
     ExpressionInferenceResult rhsResult =
         inferExpression(node.value, writeContext, isVoidAllowed: true);
@@ -6318,7 +6318,7 @@ class InferenceVisitorImpl extends InferenceVisitorBase
   ExpressionInferenceResult visitStaticGet(
       StaticGet node, DartType typeContext) {
     Member target = node.target;
-    TypeInferenceEngine.resolveInferenceNode(target, classHierarchy);
+    TypeInferenceEngine.resolveInferenceNode(target, hierarchyBuilder);
     DartType type = target.getterType;
 
     if (!isNonNullableByDefault) {
@@ -6378,7 +6378,7 @@ class InferenceVisitorImpl extends InferenceVisitorBase
   InitializerInferenceResult visitSuperInitializer(SuperInitializer node) {
     ensureMemberType(node.target);
     Substitution substitution = Substitution.fromSupertype(
-        classHierarchy.getClassAsInstanceOf(
+        hierarchyBuilder.getClassAsInstanceOf(
             thisType!.classNode, node.target.enclosingClass)!);
     FunctionType functionType = replaceReturnType(
         substitution.substituteType(node.target.function

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

@@ -9,7 +9,8 @@ import 'package:_fe_analyzer_shared/src/testing/id.dart';
 import 'package:_fe_analyzer_shared/src/util/link.dart';
 import 'package:kernel/ast.dart';
 import 'package:kernel/canonical_name.dart' as kernel;
-import 'package:kernel/class_hierarchy.dart' show ClassHierarchy;
+import 'package:kernel/class_hierarchy.dart'
+    show ClassHierarchyBase, ClassHierarchyMembers;
 import 'package:kernel/core_types.dart' show CoreTypes;
 import 'package:kernel/src/bounds_checks.dart'
     show calculateBounds, isGenericFunctionTypeOrAlias;
@@ -32,7 +33,6 @@ import '../builder/extension_builder.dart';
 import '../builder/member_builder.dart';
 import '../fasta_codes.dart';
 import '../kernel/constructor_tearoff_lowering.dart';
-import '../kernel/hierarchy/class_member.dart' show ClassMember;
 import '../kernel/internal_ast.dart';
 import '../kernel/kernel_helper.dart';
 import '../kernel/type_algorithms.dart' show hasAnyTypeVariables;
@@ -171,7 +171,9 @@ abstract class InferenceVisitorBase implements InferenceVisitor {
 
   Instrumentation? get instrumentation => _inferrer.instrumentation;
 
-  ClassHierarchy get classHierarchy => _inferrer.classHierarchy;
+  ClassHierarchyBase get hierarchyBuilder => _inferrer.engine.hierarchyBuilder;
+
+  ClassHierarchyMembers get membersBuilder => _inferrer.engine.membersBuilder;
 
   InferenceDataForTesting? get dataForTesting => _inferrer.dataForTesting;
 
@@ -366,7 +368,7 @@ abstract class InferenceVisitorBase implements InferenceVisitor {
     } else if ((constructor = engine.toBeInferred[target]) != null) {
       engine.toBeInferred.remove(target);
       engine.beingInferred[target] = constructor!;
-      constructor.inferFormalTypes(classHierarchy);
+      constructor.inferFormalTypes(hierarchyBuilder);
       engine.beingInferred.remove(target);
     }
   }
@@ -669,7 +671,7 @@ abstract class InferenceVisitorBase implements InferenceVisitor {
   TypedTearoff _tearOffCall(
       Expression expression, InterfaceType expressionType, int fileOffset) {
     Class classNode = expressionType.classNode;
-    Member callMember = classHierarchy.getInterfaceMember(classNode, callName)!;
+    Member callMember = membersBuilder.getInterfaceMember(classNode, callName)!;
     assert(callMember is Procedure && callMember.kind == ProcedureKind.Method);
 
     // Replace expression with:
@@ -719,7 +721,7 @@ abstract class InferenceVisitorBase implements InferenceVisitor {
     if (coerceExpression && expressionType is InterfaceType) {
       Class classNode = expressionType.classNode;
       Member? callMember =
-          classHierarchy.getInterfaceMember(classNode, callName);
+          membersBuilder.getInterfaceMember(classNode, callName);
       if (callMember is Procedure && callMember.kind == ProcedureKind.Method) {
         if (_shouldTearOffCall(contextType, expressionType)) {
           needsTearoff = true;
@@ -851,7 +853,7 @@ abstract class InferenceVisitorBase implements InferenceVisitor {
     if (showHideClause == null) return defaultTarget;
 
     kernel.Reference? reference = showHideClause.findShownReference(
-        name, callSiteAccessKind, classHierarchy);
+        name, callSiteAccessKind, membersBuilder);
     if (reference != null) {
       return new ObjectAccessTarget.interfaceMember(
           receiverType, reference.asMember,
@@ -1314,7 +1316,7 @@ abstract class InferenceVisitorBase implements InferenceVisitor {
     if (memberClass.typeParameters.isNotEmpty) {
       receiverType = resolveTypeParameter(receiverType);
       if (receiverType is InterfaceType) {
-        List<DartType> castedTypeArguments = classHierarchy
+        List<DartType> castedTypeArguments = hierarchyBuilder
             .getTypeArgumentsAsInstanceOf(receiverType, memberClass)!;
         calleeType = Substitution.fromPairs(
                 memberClass.typeParameters, castedTypeArguments)
@@ -1367,7 +1369,7 @@ abstract class InferenceVisitorBase implements InferenceVisitor {
   DartType? getDerivedTypeArgumentOf(DartType type, Class class_) {
     if (type is InterfaceType) {
       List<DartType>? typeArgumentsAsInstanceOfClass =
-          classHierarchy.getTypeArgumentsAsInstanceOf(type, class_);
+          hierarchyBuilder.getTypeArgumentsAsInstanceOf(type, class_);
       if (typeArgumentsAsInstanceOfClass != null) {
         return typeArgumentsAsInstanceOfClass[0];
       }
@@ -3299,7 +3301,8 @@ abstract class InferenceVisitorBase implements InferenceVisitor {
     libraryBuilder.checkBoundsInMethodInvocation(
         actualReceiverType,
         typeSchemaEnvironment,
-        classHierarchy,
+        hierarchyBuilder,
+        membersBuilder,
         actualMethodName,
         interfaceTarget,
         arguments,
@@ -3314,22 +3317,16 @@ abstract class InferenceVisitorBase implements InferenceVisitor {
     assert(inferred != null);
     // If [arguments] were inferred, check them.
 
-    libraryBuilder.checkBoundsInInstantiation(typeSchemaEnvironment,
-        classHierarchy, functionType, arguments, helper.uri, fileOffset,
+    libraryBuilder.checkBoundsInInstantiation(
+        typeSchemaEnvironment, functionType, arguments, helper.uri, fileOffset,
         inferred: inferred);
   }
 
   void _checkBoundsInFunctionInvocation(FunctionType functionType,
       String? localName, Arguments arguments, int fileOffset) {
     // If [arguments] were inferred, check them.
-    libraryBuilder.checkBoundsInFunctionInvocation(
-        typeSchemaEnvironment,
-        classHierarchy,
-        functionType,
-        localName,
-        arguments,
-        helper.uri,
-        fileOffset);
+    libraryBuilder.checkBoundsInFunctionInvocation(typeSchemaEnvironment,
+        functionType, localName, arguments, helper.uri, fileOffset);
   }
 
   /// Performs the core type inference algorithm for super method invocations.
@@ -3635,22 +3632,9 @@ abstract class InferenceVisitorBase implements InferenceVisitor {
 
   Member? _getInterfaceMember(
       Class class_, Name name, bool setter, int charOffset) {
-    ClassMember? classMember = engine.membersBuilder
-        .getInterfaceClassMember(class_, name, setter: setter);
-    if (classMember != null) {
-      if (classMember.isStatic) {
-        classMember = null;
-      } else if (classMember.isDuplicate) {
-        libraryBuilder.addProblem(
-            templateDuplicatedDeclarationUse.withArguments(name.text),
-            charOffset,
-            name.text.length,
-            helper.uri);
-        classMember = null;
-      }
-    }
-    Member? member = classMember?.getMember(engine.membersBuilder);
-    return TypeInferenceEngine.resolveInferenceNode(member, classHierarchy);
+    Member? member =
+        engine.membersBuilder.getInterfaceMember(class_, name, setter: setter);
+    return TypeInferenceEngine.resolveInferenceNode(member, hierarchyBuilder);
   }
 
   /// Determines if the given [expression]'s type is precisely known at compile

pkg/front_end/lib/src/fasta/type_inference/object_access_target.dart

@@ -419,7 +419,7 @@ class InstanceAccessTarget extends ObjectAccessTarget {
       if (resolvedReceiverType is InterfaceType) {
         setterType = Substitution.fromPairs(
                 memberClass.typeParameters,
-                base.classHierarchy.getTypeArgumentsAsInstanceOf(
+                base.hierarchyBuilder.getTypeArgumentsAsInstanceOf(
                     resolvedReceiverType, memberClass)!)
             .substituteType(setterType);
       }

pkg/front_end/lib/src/fasta/type_inference/type_inference_engine.dart

@@ -6,7 +6,8 @@ import 'package:_fe_analyzer_shared/src/flow_analysis/flow_analysis.dart';
 import 'package:_fe_analyzer_shared/src/type_inference/assigned_variables.dart';
 import 'package:_fe_analyzer_shared/src/type_inference/type_operations.dart';
 import 'package:kernel/ast.dart';
-import 'package:kernel/class_hierarchy.dart' show ClassHierarchy;
+import 'package:kernel/class_hierarchy.dart'
+    show ClassHierarchy, ClassHierarchyBase;
 import 'package:kernel/core_types.dart' show CoreTypes;
 import 'package:kernel/type_environment.dart';
 
@@ -133,8 +134,6 @@ class IncludesTypeParametersNonCovariantly implements DartTypeVisitor<bool> {
 /// (e.g. DietListener).  Derived classes should derive from
 /// [TypeInferenceEngineImpl].
 abstract class TypeInferenceEngine {
-  late ClassHierarchy classHierarchy;
-
   late ClassHierarchyBuilder hierarchyBuilder;
 
   late ClassMembersBuilder membersBuilder;
@@ -187,7 +186,7 @@ abstract class TypeInferenceEngine {
     // Field types have all been inferred so we don't need to guard against
     // cyclic dependency.
     for (SourceConstructorBuilder builder in toBeInferred.values) {
-      builder.inferFormalTypes(classHierarchy);
+      builder.inferFormalTypes(hierarchyBuilder);
     }
     toBeInferred.clear();
     for (TypeDependency typeDependency in typeDependencies.values) {
@@ -200,13 +199,12 @@ abstract class TypeInferenceEngine {
   /// given [hierarchy], using the given [coreTypes].
   void prepareTopLevel(CoreTypes coreTypes, ClassHierarchy hierarchy) {
     this.coreTypes = coreTypes;
-    this.classHierarchy = hierarchy;
     this.typeSchemaEnvironment =
         new TypeSchemaEnvironment(coreTypes, hierarchy);
   }
 
   static Member? resolveInferenceNode(
-      Member? member, ClassHierarchy hierarchy) {
+      Member? member, ClassHierarchyBase hierarchy) {
     if (member is Field) {
       DartType type = member.type;
       if (type is InferredType) {

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

@@ -5,7 +5,6 @@
 import 'package:_fe_analyzer_shared/src/flow_analysis/flow_analysis.dart';
 import 'package:_fe_analyzer_shared/src/type_inference/assigned_variables.dart';
 import 'package:kernel/ast.dart';
-import 'package:kernel/class_hierarchy.dart' show ClassHierarchy;
 
 import '../../base/instrumentation.dart' show Instrumentation;
 import '../kernel/benchmarker.dart' show BenchmarkSubdivides, Benchmarker;
@@ -116,8 +115,6 @@ class TypeInferrerImpl implements TypeInferrer {
   @override
   final bool isTopLevel;
 
-  final ClassHierarchy classHierarchy;
-
   final Instrumentation? instrumentation;
 
   @override
@@ -140,7 +137,6 @@ class TypeInferrerImpl implements TypeInferrer {
       : assert(libraryBuilder != null),
         unknownFunction = new FunctionType(
             const [], const DynamicType(), libraryBuilder.nonNullable),
-        classHierarchy = engine.classHierarchy,
         instrumentation = isTopLevel ? null : engine.instrumentation,
         typeSchemaEnvironment = engine.typeSchemaEnvironment,
         operations = new OperationsCfe(engine.typeSchemaEnvironment,

pkg/kernel/lib/ast.dart

@@ -1880,7 +1880,7 @@ class ExtensionTypeShowHideClause {
   final List<Reference> hiddenOperators = <Reference>[];
 
   Reference? findShownReference(Name name,
-      CallSiteAccessKind callSiteAccessKind, ClassHierarchy hierarchy) {
+      CallSiteAccessKind callSiteAccessKind, ClassHierarchyMembers hierarchy) {
     List<Reference> shownReferences;
     List<Reference> hiddenReferences;
     switch (callSiteAccessKind) {
@@ -1918,7 +1918,7 @@ class ExtensionTypeShowHideClause {
       Name name,
       List<Reference> references,
       List<Supertype> interfaces,
-      ClassHierarchy hierarchy,
+      ClassHierarchyMembers hierarchy,
       CallSiteAccessKind callSiteAccessKind) {
     for (Reference reference in references) {
       if (reference.asMember.name == name) {

pkg/kernel/lib/class_hierarchy.dart

@@ -42,6 +42,10 @@ abstract class ClassHierarchyBase {
   List<DartType>? getTypeArgumentsAsInstanceOf(
       InterfaceType type, Class superclass);
 
+  /// True if [subtype] inherits from [superclass] though zero or more
+  /// `extends`, `with`, and `implements` relationships.
+  bool isSubtypeOf(Class subtype, Class superclass);
+
   /// Returns the least upper bound of two interface types, as defined by Dart
   /// 1.0.
   ///
@@ -62,6 +66,21 @@ abstract class ClassHierarchyBase {
 }
 
 abstract class ClassHierarchyMembers {
+  /// Returns the instance member that would respond to a dynamic dispatch of
+  /// [name] to an instance of [class_], or `null` if no such member exists.
+  ///
+  /// If [setter] is `false`, the name is dispatched as a getter or call,
+  /// and will return a field, getter, method, or operator (or null).
+  ///
+  /// If [setter] is `true`, the name is dispatched as a setter, roughly
+  /// corresponding to `name=` in the Dart specification, but note that the
+  /// returned member will not have a name ending with `=`.  In this case,
+  /// a non-final field or setter (or null) will be returned.
+  ///
+  /// If the class is abstract, abstract members are ignored and the dispatch
+  /// is resolved if the class was not abstract.
+  Member? getDispatchTarget(Class class_, Name name, {bool setter = false});
+
   /// Returns the possibly abstract interface member of [class_] with the given
   /// [name].
   ///
@@ -111,21 +130,6 @@ abstract class ClassHierarchy
   /// be a generic class.
   Supertype? asInstantiationOf(Supertype type, Class superclass);
 
-  /// Returns the instance member that would respond to a dynamic dispatch of
-  /// [name] to an instance of [class_], or `null` if no such member exists.
-  ///
-  /// If [setter] is `false`, the name is dispatched as a getter or call,
-  /// and will return a field, getter, method, or operator (or null).
-  ///
-  /// If [setter] is `true`, the name is dispatched as a setter, roughly
-  /// corresponding to `name=` in the Dart specification, but note that the
-  /// returned member will not have a name ending with `=`.  In this case,
-  /// a non-final field or setter (or null) will be returned.
-  ///
-  /// If the class is abstract, abstract members are ignored and the dispatch
-  /// is resolved if the class was not abstract.
-  Member? getDispatchTarget(Class class_, Name name, {bool setter = false});
-
   /// Returns the list of potential targets of dynamic dispatch to an instance
   /// of [class_].
   ///
@@ -159,10 +163,6 @@ abstract class ClassHierarchy
   /// `extends` relationships.
   bool isSubclassOf(Class subclass, Class superclass);
 
-  /// True if [subtype] inherits from [superclass] though zero or more
-  /// `extends`, `with`, and `implements` relationships.
-  bool isSubtypeOf(Class subtype, Class superclass);
-
   /// True if the given class is used as the right-hand operand to a
   /// mixin application (i.e. [Class.mixedInType]).
   bool isUsedAsMixin(Class class_);