[dart2js] Handle private names correctly in K/J-model

The library wasn't taken into account when handling computing class
members in the K/J-model and not handled correctly when computing
applicable selectors. This made dart2js unable to handle members with
a name private to a different library than the enclosing library.

Fixes #33732
Fixes #49226

Change-Id: I5ba143d87662bbd42e0ff02355054e4a937be8f8
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/252665
Commit-Queue: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Stephen Adams <sra@google.com>

pkg/compiler/lib/src/common/elements.dart

@@ -6,6 +6,7 @@ import '../common.dart';
 import '../constants/constant_system.dart' as constant_system;
 import '../constants/values.dart';
 import '../elements/entities.dart';
+import '../elements/names.dart';
 import '../elements/types.dart';
 import '../inferrer/abstract_value_domain.dart';
 import '../js_backend/native_data.dart' show NativeBasicData;
@@ -325,8 +326,9 @@ abstract class CommonElements {
 
   T _findClassMember<T extends MemberEntity>(ClassEntity cls, String name,
       {bool setter = false, bool required = true}) {
-    return _env.lookupLocalClassMember(cls, name,
+    return _env.lookupLocalClassMember(
-        setter: setter, required: required) as T;
+        cls, Name(name, cls.library.canonicalUri, isSetter: setter),
+        required: required) as T;
   }
 
   ConstructorEntity _findConstructor(ClassEntity cls, String name,
@@ -371,8 +373,10 @@ abstract class CommonElements {
   /// Returns the field that holds the internal name in the implementation class
   /// for `Symbol`.
 
-  FieldEntity get symbolField => _symbolImplementationField ??=
+  FieldEntity get symbolField =>
-      _env.lookupLocalClassMember(symbolImplementationClass, '_name',
+      _symbolImplementationField ??= _env.lookupLocalClassMember(
+          symbolImplementationClass,
+          PrivateName('_name', symbolImplementationClass.library.canonicalUri),
           required: true) as FieldEntity;
 
   InterfaceType get symbolImplementationType =>
@@ -395,10 +399,13 @@ abstract class CommonElements {
   late final ConstructorEntity mapLiteralConstructorEmpty =
       _env.lookupConstructor(mapLiteralClass, '_empty');
   late final FunctionEntity mapLiteralUntypedMaker =
-      _env.lookupLocalClassMember(mapLiteralClass, '_makeLiteral')
+      _env.lookupLocalClassMember(mapLiteralClass,
+              PrivateName('_makeLiteral', mapLiteralClass.library.canonicalUri))
+          as FunctionEntity;
+  late final FunctionEntity mapLiteralUntypedEmptyMaker =
+      _env.lookupLocalClassMember(mapLiteralClass,
+              PrivateName('_makeEmpty', mapLiteralClass.library.canonicalUri))
           as FunctionEntity;
-  late final FunctionEntity mapLiteralUntypedEmptyMaker = _env
-      .lookupLocalClassMember(mapLiteralClass, '_makeEmpty') as FunctionEntity;
 
   late final ClassEntity setLiteralClass =
       _findClass(_env.lookupLibrary(Uris.dart_collection), 'LinkedHashSet')!;
@@ -408,13 +415,17 @@ abstract class CommonElements {
   late final ConstructorEntity setLiteralConstructorEmpty =
       _env.lookupConstructor(setLiteralClass, '_empty');
   late final FunctionEntity setLiteralUntypedMaker =
-      _env.lookupLocalClassMember(setLiteralClass, '_makeLiteral')
+      _env.lookupLocalClassMember(setLiteralClass,
+              PrivateName('_makeLiteral', setLiteralClass.library.canonicalUri))
+          as FunctionEntity;
+  late final FunctionEntity setLiteralUntypedEmptyMaker =
+      _env.lookupLocalClassMember(setLiteralClass,
+              PrivateName('_makeEmpty', setLiteralClass.library.canonicalUri))
           as FunctionEntity;
-  late final FunctionEntity setLiteralUntypedEmptyMaker = _env
-      .lookupLocalClassMember(setLiteralClass, '_makeEmpty') as FunctionEntity;
 
   late final FunctionEntity objectNoSuchMethod = _env.lookupLocalClassMember(
-      objectClass, Identifiers.noSuchMethod_) as FunctionEntity;
+          objectClass, const PublicName(Identifiers.noSuchMethod_))
+      as FunctionEntity;
 
   bool isDefaultNoSuchMethodImplementation(FunctionEntity element) {
     ClassEntity? classElement = element.enclosingClass;
@@ -446,15 +457,16 @@ abstract class CommonElements {
       _findAsyncHelperFunction("_wrapJsFunctionForAsync");
 
   FunctionEntity get yieldStar => _env.lookupLocalClassMember(
-      _findAsyncHelperClass("_IterationMarker"), "yieldStar") as FunctionEntity;
+      _findAsyncHelperClass("_IterationMarker"),
+      const PublicName("yieldStar")) as FunctionEntity;
 
   FunctionEntity get yieldSingle => _env.lookupLocalClassMember(
-          _findAsyncHelperClass("_IterationMarker"), "yieldSingle")
+      _findAsyncHelperClass("_IterationMarker"),
-      as FunctionEntity;
+      const PublicName("yieldSingle")) as FunctionEntity;
 
   FunctionEntity get syncStarUncaughtError => _env.lookupLocalClassMember(
-          _findAsyncHelperClass("_IterationMarker"), "uncaughtError")
+      _findAsyncHelperClass("_IterationMarker"),
-      as FunctionEntity;
+      const PublicName("uncaughtError")) as FunctionEntity;
 
   FunctionEntity get asyncStarHelper =>
       _findAsyncHelperFunction("_asyncStarHelper");
@@ -463,8 +475,8 @@ abstract class CommonElements {
       _findAsyncHelperFunction("_streamOfController");
 
   FunctionEntity get endOfIteration => _env.lookupLocalClassMember(
-          _findAsyncHelperClass("_IterationMarker"), "endOfIteration")
+      _findAsyncHelperClass("_IterationMarker"),
-      as FunctionEntity;
+      const PublicName("endOfIteration")) as FunctionEntity;
 
   ClassEntity get syncStarIterable =>
       _findAsyncHelperClass("_SyncStarIterable");
@@ -1247,17 +1259,16 @@ abstract class ElementEnvironment {
 
   /// Lookup the member [name] in [cls], fail if the class is missing and
   /// [required].
-  MemberEntity? lookupLocalClassMember(ClassEntity cls, String name,
+  MemberEntity? lookupLocalClassMember(ClassEntity cls, Name name,
-      {bool setter = false, bool required = false});
+      {bool required = false});
 
   /// Lookup the member [name] in [cls] and its superclasses.
   ///
   /// Return `null` if the member is not found in the class or any superclass.
-  MemberEntity? lookupClassMember(ClassEntity cls, String name,
+  MemberEntity? lookupClassMember(ClassEntity cls, Name name) {
-      {bool setter = false}) {
     ClassEntity? clsLocal = cls;
     while (clsLocal != null) {
-      final entity = lookupLocalClassMember(clsLocal, name, setter: setter);
+      final entity = lookupLocalClassMember(clsLocal, name);
       if (entity != null) return entity;
 
       clsLocal = getSuperClass(clsLocal);

pkg/compiler/lib/src/common/names.dart

@@ -78,6 +78,8 @@ class Names {
   /// The name of the dynamic type.
   static const Name dynamic_ = PublicName('dynamic');
 
+  static const Name EQUALS_NAME = PublicName("==");
+
   /// The name of the iterator property used in for-each loops.
   static const Name iterator = PublicName(Identifiers.iterator);
 

pkg/compiler/lib/src/dump_info.dart

@@ -28,6 +28,7 @@ import 'deferred_load/output_unit.dart' show OutputUnit, deferredPartFileName;
 import 'dump_info_javascript_monitor.dart';
 import 'elements/entities.dart';
 import 'elements/entity_utils.dart' as entity_utils;
+import 'elements/names.dart';
 import 'inferrer/abstract_value_domain.dart';
 import 'inferrer/types.dart'
     show GlobalTypeInferenceMemberResult, GlobalTypeInferenceResults;
@@ -281,8 +282,8 @@ class ElementInfoCollector {
         size: dumpInfoTask.sizeOf(element));
     state.entityToInfo[element] = closureInfo;
 
-    FunctionEntity callMethod = closedWorld.elementEnvironment
+    FunctionEntity callMethod =
-        .lookupClassMember(element, Identifiers.call);
+        closedWorld.elementEnvironment.lookupClassMember(element, Names.call);
 
     FunctionInfo functionInfo = visitFunction(callMethod);
     if (functionInfo == null) return null;
@@ -570,10 +571,12 @@ class KernelInfoCollector {
     clazz.members.forEach((ir.Member member) {
       final isSetter = member is ir.Procedure && member.isSetter;
       // clazz.members includes constructors
-      MemberEntity memberEntity = environment.lookupLocalClassMember(
+      final name = Name(member.name.text,
-              classEntity, member.name.text,
+          member.name.isPrivate ? member.name.library.importUri : null,
-              setter: isSetter) ??
+          isSetter: isSetter);
-          environment.lookupConstructor(classEntity, member.name.text);
+      MemberEntity memberEntity =
+          environment.lookupLocalClassMember(classEntity, name) ??
+              environment.lookupConstructor(classEntity, member.name.text);
       if (memberEntity == null) return;
 
       if (member.function != null) {
@@ -701,7 +704,7 @@ class KernelInfoCollector {
       final closureInfo = ClosureInfo.fromKernel(name: value.disambiguatedName);
 
       FunctionEntity callMethod = closedWorld.elementEnvironment
-          .lookupClassMember(closureClassEntity, Identifiers.call);
+          .lookupClassMember(closureClassEntity, Names.call);
       final functionInfo = visitFunction(key.function,
           functionEntity: callMethod, localFunctionInfo: value);
 
@@ -993,8 +996,8 @@ class DumpInfoAnnotator {
     kClosureInfo.outputUnit = _unitInfoForClass(element);
     kClosureInfo.size = dumpInfoTask.sizeOf(element);
 
-    FunctionEntity callMethod = closedWorld.elementEnvironment
+    FunctionEntity callMethod =
-        .lookupClassMember(element, Identifiers.call);
+        closedWorld.elementEnvironment.lookupClassMember(element, Names.call);
 
     final functionInfo =
         visitFunction(callMethod, disambiguatedElementName, isClosure: true);

pkg/compiler/lib/src/elements/names.dart

@@ -6,18 +6,16 @@ library dart2js.elements.names;
 
 import 'package:front_end/src/api_unstable/dart2js.dart' show $_;
 
-import 'entities.dart' show LibraryEntity;
-
 /// A [Name] represents the abstraction of a Dart identifier which takes privacy
 /// and setter into account.
 // TODO(johnniwinther): Try to share logic with [Selector].
 abstract class Name {
   /// Create a [Name] for an identifier [text]. If [text] begins with '_' a
-  /// private name with respect to [library] is created. If [isSetter] is `true`
+  /// private name with respect to library [uri] is created. If [isSetter] is
-  /// the created name represents the setter name 'text='.
+  /// `true` the created name represents the setter name 'text='.
-  factory Name(String text, LibraryEntity? library, {bool isSetter = false}) {
+  factory Name(String text, Uri? uri, {bool isSetter = false}) {
     if (isPrivateName(text)) {
-      return PrivateName(text, library!, isSetter: isSetter);
+      return PrivateName(text, uri!, isSetter: isSetter);
     }
     return PublicName(text, isSetter: isSetter);
   }
@@ -34,14 +32,14 @@ abstract class Name {
   /// is returned.
   Name get getter;
 
-  /// Returns the seeter name corresponding to this name. If this name is a
+  /// Returns the setter name corresponding to this name. If this name is a
-  /// getter name 'v' then the name 'v=' is returned, otherwsie the name itself
+  /// getter name 'v' then the name 'v=' is returned, otherwise the name itself
   /// is returned.
   Name get setter;
 
   /// Returns `true` if an entity of this name is accessible from library
   /// [element].
-  bool isAccessibleFrom(LibraryEntity element);
+  bool isAccessibleFrom(Uri uri);
 
   /// Returns `true` if this name is private.
   bool get isPrivate;
@@ -51,8 +49,15 @@ abstract class Name {
   bool isSimilarTo(Name other);
   int get similarHashCode;
 
+  /// Returns `true` if this name has the name [text] and [library] as [other].
+  ///
+  /// This is similar to `==` but doesn't take `isSetter` into account.
+  bool matches(Name other);
+
+  /// If this name is private, returns the [Uri] for the library from which the
+  /// name originates. Otherwise, returns `null`.
   // TODO(sra): Should this rather throw for public names?
-  LibraryEntity? get library;
+  Uri? get uri;
 
   /// Returns `true` when [s] is private if used as an identifier.
   static bool isPrivateName(String s) => !s.isEmpty && s.codeUnitAt(0) == $_;
@@ -76,7 +81,7 @@ class PublicName implements Name {
   Name get setter => isSetter ? this : PublicName(text, isSetter: true);
 
   @override
-  bool isAccessibleFrom(LibraryEntity element) => true;
+  bool isAccessibleFrom(Uri uri) => true;
 
   @override
   bool get isPrivate => false;
@@ -97,7 +102,10 @@ class PublicName implements Name {
   int get similarHashCode => text.hashCode + 11 * isSetter.hashCode;
 
   @override
-  LibraryEntity? get library => null;
+  bool matches(Name other) => text == other.text;
+
+  @override
+  Uri? get uri => null;
 
   @override
   String toString() => isSetter ? '$text=' : text;
@@ -105,34 +113,37 @@ class PublicName implements Name {
 
 class PrivateName extends PublicName {
   @override
-  final LibraryEntity library;
+  final Uri uri;
 
-  PrivateName(String text, this.library, {bool isSetter = false})
+  PrivateName(String text, this.uri, {bool isSetter = false})
       : super(text, isSetter: isSetter);
 
   @override
-  Name get getter => isSetter ? PrivateName(text, library) : this;
+  Name get getter => isSetter ? PrivateName(text, uri) : this;
 
   @override
   Name get setter {
-    return isSetter ? this : PrivateName(text, library, isSetter: true);
+    return isSetter ? this : PrivateName(text, uri, isSetter: true);
   }
 
   @override
-  bool isAccessibleFrom(LibraryEntity element) => library == element;
+  bool isAccessibleFrom(Uri uri) => this.uri == uri;
 
   @override
   bool get isPrivate => true;
 
   @override
-  int get hashCode => super.hashCode + 13 * library.hashCode;
+  int get hashCode => super.hashCode + 13 * uri.hashCode;
 
   @override
   bool operator ==(other) {
     if (other is! PrivateName) return false;
-    return super == (other) && library == other.library;
+    return super == (other) && uri == other.uri;
   }
 
   @override
-  String toString() => '${library.name}#${super.toString()}';
+  bool matches(Name other) => super.matches(other) && uri == other.uri;
+
+  @override
+  String toString() => '${uri}#${super.toString()}';
 }

pkg/compiler/lib/src/inferrer/builder.dart

@@ -1472,7 +1472,7 @@ class KernelTypeGraphBuilder extends ir.Visitor<TypeInformation>
       // We have something like `Uint32List(len)`.
       int length = _findLength(arguments);
       MemberEntity member = _elementMap.elementEnvironment
-          .lookupClassMember(constructor.enclosingClass, '[]');
+          .lookupClassMember(constructor.enclosingClass, Names.INDEX_NAME);
       TypeInformation elementType = _inferrer.returnTypeOfMember(member);
       return _inferrer.concreteTypes.putIfAbsent(
           node,

pkg/compiler/lib/src/inferrer/engine.dart

@@ -560,10 +560,10 @@ class InferrerEngine implements interfaces.InferrerEngine {
   /// implement `call`.
   FunctionEntity _lookupCallMethod(ClassEntity cls) {
     FunctionEntity function =
-        _elementEnvironment.lookupClassMember(cls, Identifiers.call);
+        _elementEnvironment.lookupClassMember(cls, Names.call);
     if (function == null || function.isAbstract) {
       function =
-          _elementEnvironment.lookupClassMember(cls, Identifiers.noSuchMethod_);
+          _elementEnvironment.lookupClassMember(cls, Names.noSuchMethod_);
     }
     return function;
   }

pkg/compiler/lib/src/ir/element_map.dart

@@ -8,6 +8,7 @@ import 'package:kernel/core_types.dart' as ir;
 import '../common.dart';
 import '../common/elements.dart';
 import '../elements/entities.dart';
+import '../elements/names.dart';
 import '../elements/types.dart';
 import '../ordered_typeset.dart';
 import '../universe/call_structure.dart';
@@ -20,6 +21,11 @@ abstract class IrToElementMap {
   /// Returns the [DartType] corresponding to [type].
   DartType getDartType(ir.DartType type);
 
+  /// Returns the [Name] corresponding to [name].
+  ///
+  /// If [setter] is `true`, the setter name is returned.
+  Name getName(ir.Name name, {bool setter = false});
+
   /// Returns the [MemberEntity] corresponding to the member [node].
   MemberEntity getMember(ir.Member node);
 

pkg/compiler/lib/src/js_backend/namer.dart

@@ -648,7 +648,8 @@ class Namer extends ModularNamer {
     // Public names are easy.
     if (!originalName.isPrivate) return text;
 
-    LibraryEntity library = originalName.library;
+    LibraryEntity library =
+        _elementEnvironment.lookupLibrary(originalName.uri, required: true);
 
     // The first library asking for a short private name wins.
     LibraryEntity owner =
@@ -888,13 +889,13 @@ class Namer extends ModularNamer {
     // No superclass uses the disambiguated name as a property name, so we can
     // use it for this field. This generates nicer field names since otherwise
     // the field name would have to be mangled.
-    return _disambiguateMember(Name(element.name, element.library));
+    return _disambiguateMember(
+        Name(element.name, element.library.canonicalUri));
   }
 
   bool _isShadowingSuperField(FieldEntity element) {
     assert(element.isField);
-    String fieldName = element.name;
+    Name fieldName = element.memberName;
-    bool isPrivate = Name.isPrivateName(fieldName);
     LibraryEntity memberLibrary = element.library;
     ClassEntity lookupClass =
         _elementEnvironment.getSuperClass(element.enclosingClass);
@@ -903,7 +904,7 @@ class Namer extends ModularNamer {
           _elementEnvironment.lookupLocalClassMember(lookupClass, fieldName);
       if (foundMember != null) {
         if (foundMember.isField) {
-          if (!isPrivate || memberLibrary == foundMember.library) {
+          if (!fieldName.isPrivate || memberLibrary == foundMember.library) {
             // Private fields can only be shadowed by a field declared in the
             // same library.
             return true;
@@ -1030,8 +1031,10 @@ class Namer extends ModularNamer {
   jsAst.Name _disambiguateMember(Name originalName,
       [List<String> suffixes = const []]) {
     // Build a string encoding the library name, if the name is private.
-    String libraryKey =
+    String libraryKey = originalName.isPrivate
-        originalName.isPrivate ? _generateLibraryKey(originalName.library) : '';
+        ? _generateLibraryKey(
+            _elementEnvironment.lookupLibrary(originalName.uri, required: true))
+        : '';
 
     // In the unique key, separate the name parts by '@'.
     // This avoids clashes since the original names cannot contain that symbol.

pkg/compiler/lib/src/js_backend/resolution_listener.dart

@@ -7,7 +7,7 @@
 library js_backend.backend.resolution_listener;
 
 import '../common/elements.dart' show KCommonElements, KElementEnvironment;
-import '../common/names.dart' show Identifiers;
+import '../common/names.dart' show Identifiers, Names;
 import '../constants/values.dart';
 import '../deferred_load/deferred_load.dart';
 import '../elements/entities.dart';
@@ -160,8 +160,8 @@ class ResolutionEnqueuerListener extends EnqueuerListener {
     enqueuer.applyImpact(_customElementsAnalysis.flush());
 
     for (ClassEntity cls in recentClasses) {
-      MemberEntity element = _elementEnvironment.lookupLocalClassMember(
+      MemberEntity element =
-          cls, Identifiers.noSuchMethod_);
+          _elementEnvironment.lookupLocalClassMember(cls, Names.noSuchMethod_);
       if (element != null &&
           element.isInstanceMember &&
           element.isFunction &&

pkg/compiler/lib/src/js_backend/runtime_types.dart

@@ -9,7 +9,7 @@ library js_backend.runtime_types;
 import '../common.dart';
 import '../common/elements.dart'
     show ElementEnvironment, JCommonElements, JElementEnvironment;
-import '../common/names.dart' show Identifiers;
+import '../common/names.dart' show Names;
 import '../elements/entities.dart';
 import '../elements/types.dart';
 import '../js/js.dart' as jsAst;
@@ -769,7 +769,7 @@ ClassFunctionType _computeFunctionType(
   if (cls.isClosure) {
     // Use signature function if available.
     signatureFunction =
-        elementEnvironment.lookupLocalClassMember(cls, Identifiers.signature);
+        elementEnvironment.lookupLocalClassMember(cls, Names.signature);
     if (signatureFunction == null) {
       // In Dart 2, a closure only needs its function type if it has a
       // signature function.
@@ -780,7 +780,7 @@ ClassFunctionType _computeFunctionType(
     return null;
   }
   MemberEntity call =
-      elementEnvironment.lookupLocalClassMember(cls, Identifiers.call);
+      elementEnvironment.lookupLocalClassMember(cls, Names.call);
   if (call != null && call.isFunction) {
     FunctionEntity callFunction = call;
     FunctionType callType = elementEnvironment.getFunctionType(callFunction);

pkg/compiler/lib/src/js_model/closure_migrated.dart

@@ -60,7 +60,7 @@ class JRecordField extends JField implements JRecordFieldInterface {
 
   JRecordField(String name, this.box, {required bool isConst})
       : super(box.container.library as JLibrary, box.container as JClass,
-            Name(name, box.container.library),
+            Name(name, box.container.library.canonicalUri),
             isStatic: false, isAssignable: true, isConst: isConst);
 
   factory JRecordField.readFromDataSource(DataSourceReader source) {
@@ -163,7 +163,7 @@ class JClosureField extends JField implements PrivatelyNamedJSEntity {
       : this.internal(
             containingClass.closureClassEntity.library,
             containingClass.closureClassEntity as JClosureClass,
-            Name(name, containingClass.closureClassEntity.library),
+            Name(name, containingClass.closureClassEntity.library.canonicalUri),
             declaredName,
             isAssignable: isAssignable,
             isConst: isConst);
@@ -183,7 +183,7 @@ class JClosureField extends JField implements PrivatelyNamedJSEntity {
     bool isAssignable = source.readBool();
     source.end(tag);
     return JClosureField.internal(
-        cls.library, cls, Name(name, cls.library), declaredName,
+        cls.library, cls, Name(name, cls.library.canonicalUri), declaredName,
         isAssignable: isAssignable, isConst: isConst);
   }
 

pkg/compiler/lib/src/js_model/element_map_impl.dart

@@ -172,7 +172,8 @@ class JsKernelToElementMap
       LibraryEntity newLibrary = libraries.getEntity(oldLibrary.libraryIndex);
       IndexedClass newClass =
           JClass(newLibrary, oldClass.name, isAbstract: oldClass.isAbstract);
-      JClassEnv newEnv = env.convert(_elementMap, liveMemberUsage);
+      JClassEnv newEnv = env.convert(_elementMap, liveMemberUsage,
+          (ir.Library library) => libraryMap[library]);
       classMap[env.cls] = classes.register(newClass, data.convert(), newEnv);
       assert(newClass.classIndex == oldClass.classIndex);
       libraries.getEnv(newClass.library).registerClass(newClass.name, newEnv);
@@ -194,8 +195,7 @@ class JsKernelToElementMap
       ClassEntity newClass =
           oldClass != null ? classes.getEntity(oldClass.classIndex) : null;
       IndexedMember newMember;
-      Name memberName = Name(oldMember.memberName.text, newLibrary,
+      Name memberName = oldMember.memberName;
-          isSetter: oldMember.memberName.isSetter);
       if (oldMember.isField) {
         IndexedField field = oldMember;
         newMember = JField(newLibrary, newClass, memberName,
@@ -610,11 +610,10 @@ class JsKernelToElementMap
     });
   }
 
-  MemberEntity lookupClassMember(IndexedClass cls, String name,
+  MemberEntity lookupClassMember(IndexedClass cls, Name name) {
-      {bool setter = false}) {
     assert(checkFamily(cls));
     JClassEnv classEnv = classes.getEnv(cls);
-    return classEnv.lookupMember(this, name, setter: setter);
+    return classEnv.lookupMember(this, name);
   }
 
   ConstructorEntity lookupConstructor(IndexedClass cls, String name) {
@@ -647,7 +646,7 @@ class JsKernelToElementMap
     assert(checkFamily(cls));
     if (data is JClassDataImpl && !data.isCallTypeComputed) {
       MemberEntity callMember =
-          _elementEnvironment.lookupClassMember(cls, Identifiers.call);
+          _elementEnvironment.lookupClassMember(cls, Names.call);
       if (callMember is FunctionEntity &&
           callMember.isFunction &&
           !callMember.isAbstract) {
@@ -1237,8 +1236,9 @@ class JsKernelToElementMap
   }
 
   @override
-  Name getName(ir.Name name) {
+  Name getName(ir.Name name, {bool setter = false}) {
-    return Name(name.text, name.isPrivate ? getLibrary(name.library) : null);
+    return Name(name.text, name.isPrivate ? name.library.importUri : null,
+        isSetter: setter);
   }
 
   @override
@@ -1305,13 +1305,13 @@ class JsKernelToElementMap
 
   Selector getGetterSelector(ir.Name irName) {
     Name name =
-        Name(irName.text, irName.isPrivate ? getLibrary(irName.library) : null);
+        Name(irName.text, irName.isPrivate ? irName.library.importUri : null);
     return Selector.getter(name);
   }
 
   Selector getSetterSelector(ir.Name irName) {
     Name name =
-        Name(irName.text, irName.isPrivate ? getLibrary(irName.library) : null);
+        Name(irName.text, irName.isPrivate ? irName.library.importUri : null);
     return Selector.setter(name);
   }
 
@@ -1526,8 +1526,8 @@ class JsKernelToElementMap
   FunctionEntity getSuperNoSuchMethod(ClassEntity cls) {
     while (cls != null) {
       cls = elementEnvironment.getSuperClass(cls);
-      MemberEntity member = elementEnvironment.lookupLocalClassMember(
+      MemberEntity member =
-          cls, Identifiers.noSuchMethod_);
+          elementEnvironment.lookupLocalClassMember(cls, Names.noSuchMethod_);
       if (member != null && !member.isAbstract) {
         if (member.isFunction) {
           FunctionEntity function = member;
@@ -1541,7 +1541,7 @@ class JsKernelToElementMap
       }
     }
     FunctionEntity function = elementEnvironment.lookupLocalClassMember(
-        commonElements.objectClass, Identifiers.noSuchMethod_);
+        commonElements.objectClass, Names.noSuchMethod_);
     assert(function != null,
         failedAt(cls, "No super noSuchMethod found for class $cls."));
     return function;
@@ -1759,7 +1759,7 @@ class JsKernelToElementMap
       InterfaceType memberThisType,
       ir.VariableDeclaration variable,
       BoxLocal boxLocal,
-      Map<String, MemberEntity> memberMap) {
+      Map<Name, MemberEntity> memberMap) {
     JRecordField boxedField =
         JRecordField(variable.name, boxLocal, isConst: variable.isConst);
     members.register(
@@ -1768,7 +1768,7 @@ class JsKernelToElementMap
             ClosureMemberDefinition(computeSourceSpanFromTreeNode(variable),
                 MemberKind.closureField, variable),
             memberThisType));
-    memberMap[boxedField.name] = boxedField;
+    memberMap[boxedField.memberName] = boxedField;
 
     return boxedField;
   }
@@ -1783,7 +1783,7 @@ class JsKernelToElementMap
     if (info.boxedVariables.isNotEmpty) {
       NodeBox box = info.capturedVariablesAccessor;
 
-      Map<String, IndexedMember> memberMap = {};
+      Map<Name, IndexedMember> memberMap = {};
       closureMigrated.JRecord container =
           closureMigrated.JRecord(member.library, box.name);
       BoxLocal boxLocal = BoxLocal(container);
@@ -1851,7 +1851,7 @@ class JsKernelToElementMap
     }
     String name = _computeClosureName(node);
     SourceSpan location = computeSourceSpanFromTreeNode(node);
-    Map<String, IndexedMember> memberMap = {};
+    Map<Name, IndexedMember> memberMap = {};
 
     JClass classEntity = closureMigrated.JClosureClass(enclosingLibrary, name);
     // Create a classData and set up the interfaces and subclass
@@ -1918,7 +1918,7 @@ class JsKernelToElementMap
             closureData.callType,
             node,
             typeVariableAccess));
-    memberMap[callMethod.name] = closureClassInfo.callMethod = callMethod;
+    memberMap[callMethod.memberName] = closureClassInfo.callMethod = callMethod;
     return closureClassInfo;
   }
 
@@ -1928,7 +1928,7 @@ class JsKernelToElementMap
       InterfaceType memberThisType,
       KernelScopeInfo info,
       Map<ir.VariableDeclaration, JRecordField> recordFieldsVisibleInScope,
-      Map<String, MemberEntity> memberMap) {
+      Map<Name, MemberEntity> memberMap) {
     // TODO(efortuna): Limit field number usage to when we need to distinguish
     // between two variables with the same name from different scopes.
     int fieldNumber = 0;
@@ -2027,7 +2027,7 @@ class JsKernelToElementMap
       ir.VariableDeclaration capturedLocal,
       JsClosureClassInfo closureClassInfo,
       InterfaceType memberThisType,
-      Map<String, MemberEntity> memberMap,
+      Map<Name, MemberEntity> memberMap,
       ir.TreeNode sourceNode,
       Map<ir.VariableDeclaration, JRecordField> recordFieldsVisibleInScope,
       int fieldNumber) {
@@ -2051,7 +2051,7 @@ class JsKernelToElementMap
             ClosureMemberDefinition(computeSourceSpanFromTreeNode(sourceNode),
                 MemberKind.closureField, sourceNode),
             memberThisType));
-    memberMap[closureField.name] = closureField;
+    memberMap[closureField.memberName] = closureField;
     closureClassInfo.registerFieldForLocal(recordField.box, closureField);
     closureClassInfo.registerFieldForBoxedVariable(capturedLocal, recordField);
     return true;
@@ -2059,7 +2059,7 @@ class JsKernelToElementMap
 
   void _constructSignatureMethod(
       JsClosureClassInfo closureClassInfo,
-      Map<String, MemberEntity> memberMap,
+      Map<Name, MemberEntity> memberMap,
       ir.FunctionNode closureSourceNode,
       InterfaceType memberThisType,
       SourceSpan location,
@@ -2074,7 +2074,7 @@ class JsKernelToElementMap
             memberThisType,
             closureSourceNode.typeParameters,
             typeVariableAccess));
-    memberMap[signatureMethod.name] =
+    memberMap[signatureMethod.memberName] =
         closureClassInfo.signatureMethod = signatureMethod;
   }
 
@@ -2082,7 +2082,7 @@ class JsKernelToElementMap
       String name,
       JsClosureClassInfo closureClassInfo,
       InterfaceType memberThisType,
-      Map<String, MemberEntity> memberMap,
+      Map<Name, MemberEntity> memberMap,
       ir.TreeNode sourceNode,
       bool isConst,
       bool isAssignable,
@@ -2097,7 +2097,7 @@ class JsKernelToElementMap
             ClosureMemberDefinition(computeSourceSpanFromTreeNode(sourceNode),
                 MemberKind.closureField, sourceNode),
             memberThisType));
-    memberMap[closureField.name] = closureField;
+    memberMap[closureField.memberName] = closureField;
     return closureField;
   }
 
@@ -2361,10 +2361,9 @@ class JsElementEnvironment extends ElementEnvironment
   }
 
   @override
-  MemberEntity lookupLocalClassMember(ClassEntity cls, String name,
+  MemberEntity lookupLocalClassMember(ClassEntity cls, Name name,
-      {bool setter = false, bool required = false}) {
+      {bool required = false}) {
-    MemberEntity member =
+    MemberEntity member = elementMap.lookupClassMember(cls, name);
-        elementMap.lookupClassMember(cls, name, setter: setter);
     if (member == null && required) {
       throw failedAt(CURRENT_ELEMENT_SPANNABLE,
           "The member '$name' was not found in ${cls.name}.");

pkg/compiler/lib/src/js_model/elements.dart

@@ -281,8 +281,8 @@ class JGenerativeConstructor extends JConstructor {
     bool isExternal = source.readBool();
     bool isConst = source.readBool();
     source.end(tag);
-    return JGenerativeConstructor(
+    return JGenerativeConstructor(enclosingClass,
-        enclosingClass, Name(name, enclosingClass.library), parameterStructure,
+        Name(name, enclosingClass.library.canonicalUri), parameterStructure,
         isExternal: isExternal, isConst: isConst);
   }
 
@@ -331,8 +331,8 @@ class JFactoryConstructor extends JConstructor {
     bool isConst = source.readBool();
     bool isFromEnvironmentConstructor = source.readBool();
     source.end(tag);
-    return JFactoryConstructor(
+    return JFactoryConstructor(enclosingClass,
-        enclosingClass, Name(name, enclosingClass.library), parameterStructure,
+        Name(name, enclosingClass.library.canonicalUri), parameterStructure,
         isExternal: isExternal,
         isConst: isConst,
         isFromEnvironmentConstructor: isFromEnvironmentConstructor);
@@ -423,7 +423,7 @@ class JMethod extends JFunction {
         library = enclosingClass.library;
         break;
     }
-    String name = source.readString();
+    Name memberName = source.readMemberName();
     ParameterStructure parameterStructure =
         ParameterStructure.readFromDataSource(source);
     AsyncMarker asyncMarker = source.readEnum(AsyncMarker.values);
@@ -431,8 +431,8 @@ class JMethod extends JFunction {
     bool isExternal = source.readBool();
     bool isAbstract = source.readBool();
     source.end(tag);
-    return JMethod(library, enclosingClass, Name(name, library),
+    return JMethod(
-        parameterStructure, asyncMarker,
+        library, enclosingClass, memberName, parameterStructure, asyncMarker,
         isStatic: isStatic, isExternal: isExternal, isAbstract: isAbstract);
   }
 
@@ -447,7 +447,7 @@ class JMethod extends JFunction {
       sink.writeEnum(MemberContextKind.library);
       sink.writeLibrary(library);
     }
-    sink.writeString(name);
+    sink.writeMemberName(memberName);
     parameterStructure.writeToDataSink(sink);
     sink.writeEnum(asyncMarker);
     sink.writeBool(isStatic);
@@ -531,13 +531,13 @@ class JGetter extends JFunction {
         library = enclosingClass.library;
         break;
     }
-    String name = source.readString();
+    Name memberName = source.readMemberName();
     AsyncMarker asyncMarker = source.readEnum(AsyncMarker.values);
     bool isStatic = source.readBool();
     bool isExternal = source.readBool();
     bool isAbstract = source.readBool();
     source.end(tag);
-    return JGetter(library, enclosingClass, Name(name, library), asyncMarker,
+    return JGetter(library, enclosingClass, memberName, asyncMarker,
         isStatic: isStatic, isExternal: isExternal, isAbstract: isAbstract);
   }
 
@@ -552,7 +552,7 @@ class JGetter extends JFunction {
       sink.writeEnum(MemberContextKind.library);
       sink.writeLibrary(library);
     }
-    sink.writeString(name);
+    sink.writeMemberName(memberName);
     sink.writeEnum(asyncMarker);
     sink.writeBool(isStatic);
     sink.writeBool(isExternal);
@@ -597,12 +597,12 @@ class JSetter extends JFunction {
         library = enclosingClass.library;
         break;
     }
-    String name = source.readString();
+    Name memberName = source.readMemberName();
     bool isStatic = source.readBool();
     bool isExternal = source.readBool();
     bool isAbstract = source.readBool();
     source.end(tag);
-    return JSetter(library, enclosingClass, Name(name, library, isSetter: true),
+    return JSetter(library, enclosingClass, memberName,
         isStatic: isStatic, isExternal: isExternal, isAbstract: isAbstract);
   }
 
@@ -617,7 +617,7 @@ class JSetter extends JFunction {
       sink.writeEnum(MemberContextKind.library);
       sink.writeLibrary(library);
     }
-    sink.writeString(name);
+    sink.writeMemberName(memberName);
     sink.writeBool(isStatic);
     sink.writeBool(isExternal);
     sink.writeBool(isAbstract);
@@ -664,12 +664,12 @@ class JField extends JMember implements FieldEntity, IndexedField {
         library = enclosingClass.library;
         break;
     }
-    String name = source.readString();
+    Name memberName = source.readMemberName();
     bool isStatic = source.readBool();
     bool isAssignable = source.readBool();
     bool isConst = source.readBool();
     source.end(tag);
-    return JField(library, enclosingClass, Name(name, library),
+    return JField(library, enclosingClass, memberName,
         isStatic: isStatic, isAssignable: isAssignable, isConst: isConst);
   }
 
@@ -684,7 +684,7 @@ class JField extends JMember implements FieldEntity, IndexedField {
       sink.writeEnum(MemberContextKind.library);
       sink.writeLibrary(library);
     }
-    sink.writeString(name);
+    sink.writeMemberName(memberName);
     sink.writeBool(isStatic);
     sink.writeBool(isAssignable);
     sink.writeBool(isConst);

pkg/compiler/lib/src/js_model/env.dart

@@ -11,6 +11,7 @@ import 'package:kernel/ast.dart' as ir;
 import '../constants/values.dart';
 import '../elements/entities.dart';
 import '../elements/indexed.dart';
+import '../elements/names.dart';
 import '../elements/types.dart';
 import '../ir/element_map.dart';
 import '../ir/static_type_cache.dart';
@@ -217,8 +218,7 @@ abstract class JClassEnv {
   /// Return the [MemberEntity] for the member [name] in the class. If [setter]
   /// is `true`, the setter or assignable field corresponding to [name] is
   /// returned.
-  MemberEntity lookupMember(IrToElementMap elementMap, String name,
+  MemberEntity lookupMember(IrToElementMap elementMap, Name name);
-      {bool setter = false});
 
   /// Calls [f] for each member of [cls].
   void forEachMember(IrToElementMap elementMap, void f(MemberEntity member));
@@ -244,8 +244,7 @@ class JClassEnvImpl implements JClassEnv {
   @override
   final ir.Class cls;
   final Map<String, ir.Member> _constructorMap;
-  final Map<String, ir.Member> _memberMap;
+  final Map<Name, ir.Member> _memberMap;
-  final Map<String, ir.Member> _setterMap;
   final List<ir.Member> _members; // in declaration order.
   @override
   final bool isMixinApplicationWithMembers;
@@ -253,23 +252,20 @@ class JClassEnvImpl implements JClassEnv {
   /// Constructor bodies created for this class.
   List<ConstructorBodyEntity> _constructorBodyList;
 
-  JClassEnvImpl(this.cls, this._constructorMap, this._memberMap,
+  JClassEnvImpl(this.cls, this._constructorMap, this._memberMap, this._members,
-      this._setterMap, this._members, this.isMixinApplicationWithMembers);
+      this.isMixinApplicationWithMembers);
 
   factory JClassEnvImpl.readFromDataSource(DataSourceReader source) {
     source.begin(tag);
     ir.Class cls = source.readClassNode();
     Map<String, ir.Member> constructorMap =
         source.readStringMap(source.readMemberNode);
-    Map<String, ir.Member> memberMap =
+    Map<Name, ir.Member> memberMap = source.readNameMap(source.readMemberNode);
-        source.readStringMap(source.readMemberNode);
-    Map<String, ir.Member> setterMap =
-        source.readStringMap(source.readMemberNode);
     List<ir.Member> members = source.readMemberNodes();
     bool isSuperMixinApplication = source.readBool();
     source.end(tag);
-    return JClassEnvImpl(cls, constructorMap, memberMap, setterMap, members,
+    return JClassEnvImpl(
-        isSuperMixinApplication);
+        cls, constructorMap, memberMap, members, isSuperMixinApplication);
   }
 
   @override
@@ -278,8 +274,7 @@ class JClassEnvImpl implements JClassEnv {
     sink.begin(tag);
     sink.writeClassNode(cls);
     sink.writeStringMap(_constructorMap, sink.writeMemberNode);
-    sink.writeStringMap(_memberMap, sink.writeMemberNode);
+    sink.writeNameMap(_memberMap, sink.writeMemberNode);
-    sink.writeStringMap(_setterMap, sink.writeMemberNode);
     sink.writeMemberNodes(_members);
     sink.writeBool(isMixinApplicationWithMembers);
     sink.end(tag);
@@ -289,9 +284,8 @@ class JClassEnvImpl implements JClassEnv {
   bool get isUnnamedMixinApplication => cls.isAnonymousMixin;
 
   @override
-  MemberEntity lookupMember(IrToElementMap elementMap, String name,
+  MemberEntity lookupMember(IrToElementMap elementMap, Name name) {
-      {bool setter = false}) {
+    ir.Member member = _memberMap[name];
-    ir.Member member = setter ? _setterMap[name] : _memberMap[name];
     return member != null ? elementMap.getMember(member) : null;
   }
 
@@ -332,14 +326,14 @@ class RecordEnv implements JClassEnv {
   /// debugging data stream.
   static const String tag = 'record-env';
 
-  final Map<String, IndexedMember> _memberMap;
+  final Map<Name, IndexedMember> _memberMap;
 
   RecordEnv(this._memberMap);
 
   factory RecordEnv.readFromDataSource(DataSourceReader source) {
     source.begin(tag);
-    Map<String, IndexedMember> _memberMap =
+    Map<Name, IndexedMember> _memberMap =
-        source.readStringMap(() => source.readMember());
+        source.readNameMap(() => source.readMember());
     source.end(tag);
     return RecordEnv(_memberMap);
   }
@@ -348,7 +342,7 @@ class RecordEnv implements JClassEnv {
   void writeToDataSink(DataSinkWriter sink) {
     sink.writeEnum(JClassEnvKind.record);
     sink.begin(tag);
-    sink.writeStringMap(
+    sink.writeNameMap(
         _memberMap, (IndexedMember member) => sink.writeMember(member));
     sink.end(tag);
   }
@@ -376,8 +370,7 @@ class RecordEnv implements JClassEnv {
   }
 
   @override
-  MemberEntity lookupMember(IrToElementMap elementMap, String name,
+  MemberEntity lookupMember(IrToElementMap elementMap, Name name) {
-      {bool setter = false}) {
     return _memberMap[name];
   }
 
@@ -396,12 +389,12 @@ class ClosureClassEnv extends RecordEnv {
   /// debugging data stream.
   static const String tag = 'closure-class-env';
 
-  ClosureClassEnv(Map<String, MemberEntity> memberMap) : super(memberMap);
+  ClosureClassEnv(Map<Name, MemberEntity> memberMap) : super(memberMap);
 
   factory ClosureClassEnv.readFromDataSource(DataSourceReader source) {
     source.begin(tag);
-    Map<String, IndexedMember> _memberMap =
+    Map<Name, IndexedMember> _memberMap =
-        source.readStringMap(() => source.readMember());
+        source.readNameMap(() => source.readMember());
     source.end(tag);
     return ClosureClassEnv(_memberMap);
   }
@@ -410,20 +403,10 @@ class ClosureClassEnv extends RecordEnv {
   void writeToDataSink(DataSinkWriter sink) {
     sink.writeEnum(JClassEnvKind.closure);
     sink.begin(tag);
-    sink.writeStringMap(
+    sink.writeNameMap(
         _memberMap, (IndexedMember member) => sink.writeMember(member));
     sink.end(tag);
   }
-
-  @override
-  MemberEntity lookupMember(IrToElementMap elementMap, String name,
-      {bool setter = false}) {
-    if (setter) {
-      // All closure fields are final.
-      return null;
-    }
-    return super.lookupMember(elementMap, name, setter: setter);
-  }
 }
 
 /// Enum used for identifying [JClassData] subclasses in serialization.

pkg/compiler/lib/src/js_model/js_world.dart

@@ -545,11 +545,9 @@ class JsClosedWorld implements JClosedWorld {
   @override
   bool hasElementIn(ClassEntity cls, Name name, Entity element) {
     while (cls != null) {
-      MemberEntity member = elementEnvironment
+      MemberEntity member =
-          .lookupLocalClassMember(cls, name.text, setter: name.isSetter);
+          elementEnvironment.lookupLocalClassMember(cls, name);
-      if (member != null &&
+      if (member != null && !member.isAbstract) {
-          !member.isAbstract &&
-          (!name.isPrivate || member.library == name.library)) {
         return member == element;
       }
       cls = elementEnvironment.getSuperClass(cls);
@@ -563,8 +561,8 @@ class JsClosedWorld implements JClosedWorld {
       {ClassEntity stopAtSuperclass}) {
     assert(classHierarchy.isInstantiated(cls),
         failedAt(cls, '$cls has not been instantiated.'));
-    MemberEntity element = elementEnvironment
+    MemberEntity element =
-        .lookupClassMember(cls, selector.name, setter: selector.isSetter);
+        elementEnvironment.lookupClassMember(cls, selector.memberName);
     if (element == null) return false;
 
     if (element.isAbstract) {

pkg/compiler/lib/src/js_model/js_world_builder.dart

@@ -14,7 +14,6 @@ import '../constants/values.dart';
 import '../deferred_load/output_unit.dart' show OutputUnit, OutputUnitData;
 import '../elements/entities.dart';
 import '../elements/indexed.dart';
-import '../elements/names.dart';
 import '../elements/types.dart';
 import '../inferrer/abstract_value_strategy.dart';
 import '../ir/closure.dart';
@@ -302,17 +301,7 @@ class JsClosedWorldBuilder {
     Set<FunctionEntity> methodsNeedingSignature =
         map.toBackendFunctionSet(rtiNeed.methodsNeedingSignature);
     Set<Selector> selectorsNeedingTypeArguments =
-        rtiNeed.selectorsNeedingTypeArguments.map((Selector selector) {
+        rtiNeed.selectorsNeedingTypeArguments;
-      if (selector.memberName.isPrivate) {
-        return Selector(
-            selector.kind,
-            PrivateName(selector.memberName.text,
-                map.toBackendLibrary(selector.memberName.library),
-                isSetter: selector.memberName.isSetter),
-            selector.callStructure);
-      }
-      return selector;
-    }).toSet();
     return RuntimeTypesNeedImpl(
         _elementEnvironment,
         classesNeedingTypeArguments,

pkg/compiler/lib/src/kernel/element_map_impl.dart

@@ -258,11 +258,11 @@ class KernelToElementMap
     return cls;
   }
 
-  MemberEntity lookupClassMember(IndexedClass cls, String name,
+  MemberEntity lookupClassMember(IndexedClass cls, Name name,
       {bool setter = false}) {
     assert(checkFamily(cls));
     KClassEnv classEnv = classes.getEnv(cls);
-    return classEnv.lookupMember(this, name, setter: setter);
+    return classEnv.lookupMember(this, name);
   }
 
   ConstructorEntity lookupConstructor(IndexedClass cls, String name) {
@@ -303,7 +303,7 @@ class KernelToElementMap
     assert(checkFamily(cls));
     if (data is KClassDataImpl && !data.isCallTypeComputed) {
       MemberEntity callMember =
-          _elementEnvironment.lookupClassMember(cls, Identifiers.call);
+          _elementEnvironment.lookupClassMember(cls, Names.call);
       if (callMember is FunctionEntity &&
           callMember.isFunction &&
           !callMember.isAbstract) {
@@ -898,10 +898,10 @@ class KernelToElementMap
                 : ir.EvaluationMode.strong);
   }
 
-  /// Returns the [Name] corresponding to [name].
   @override
-  Name getName(ir.Name name) {
+  Name getName(ir.Name name, {bool setter = false}) {
-    return Name(name.text, name.isPrivate ? getLibrary(name.library) : null);
+    return Name(name.text, name.isPrivate ? name.library.importUri : null,
+        isSetter: setter);
   }
 
   /// Returns the [CallStructure] corresponding to the [arguments].
@@ -964,13 +964,13 @@ class KernelToElementMap
 
   Selector getGetterSelector(ir.Name irName) {
     Name name =
-        Name(irName.text, irName.isPrivate ? getLibrary(irName.library) : null);
+        Name(irName.text, irName.isPrivate ? irName.library.importUri : null);
     return Selector.getter(name);
   }
 
   Selector getSetterSelector(ir.Name irName) {
     Name name =
-        Name(irName.text, irName.isPrivate ? getLibrary(irName.library) : null);
+        Name(irName.text, irName.isPrivate ? irName.library.importUri : null);
     return Selector.setter(name);
   }
 
@@ -1221,8 +1221,8 @@ class KernelToElementMap
   FunctionEntity getSuperNoSuchMethod(ClassEntity cls) {
     while (cls != null) {
       cls = elementEnvironment.getSuperClass(cls);
-      MemberEntity member = elementEnvironment.lookupLocalClassMember(
+      MemberEntity member =
-          cls, Identifiers.noSuchMethod_);
+          elementEnvironment.lookupLocalClassMember(cls, Names.noSuchMethod_);
       if (member != null && !member.isAbstract) {
         if (member.isFunction) {
           FunctionEntity function = member;
@@ -1236,7 +1236,7 @@ class KernelToElementMap
       }
     }
     FunctionEntity function = elementEnvironment.lookupLocalClassMember(
-        commonElements.objectClass, Identifiers.noSuchMethod_);
+        commonElements.objectClass, Names.noSuchMethod_);
     assert(function != null,
         failedAt(cls, "No super noSuchMethod found for class $cls."));
     return function;
@@ -1899,10 +1899,9 @@ class KernelElementEnvironment extends ElementEnvironment
   }
 
   @override
-  MemberEntity lookupLocalClassMember(ClassEntity cls, String name,
+  MemberEntity lookupLocalClassMember(ClassEntity cls, Name name,
-      {bool setter = false, bool required = false}) {
+      {bool required = false}) {
-    MemberEntity member =
+    MemberEntity member = elementMap.lookupClassMember(cls, name);
-        elementMap.lookupClassMember(cls, name, setter: setter);
     if (member == null && required) {
       throw failedAt(CURRENT_ELEMENT_SPANNABLE,
           "The member '$name' was not found in ${cls.name}.");

pkg/compiler/lib/src/kernel/env.dart

@@ -16,6 +16,7 @@ import 'package:collection/collection.dart' show mergeSort; // a stable sort.
 import '../common.dart';
 import '../constants/values.dart';
 import '../elements/entities.dart';
+import '../elements/names.dart';
 import '../elements/types.dart';
 import '../ir/element_map.dart';
 import '../ir/static_type_cache.dart';
@@ -162,7 +163,7 @@ class KLibraryEnv {
 
   /// Convert this [KLibraryEnv] to a corresponding [JLibraryEnv] containing
   /// only the members in [liveMembers].
-  JLibraryEnv convert(IrToElementMap elementMap,
+  JLibraryEnv convert(IrToElementMap kElementMap,
       Map<MemberEntity, MemberUsage> liveMemberUsage) {
     Map<String, ir.Member> memberMap;
     Map<String, ir.Member> setterMap;
@@ -171,7 +172,7 @@ class KLibraryEnv {
     } else {
       memberMap = <String, ir.Member>{};
       _memberMap.forEach((String name, ir.Member node) {
-        MemberEntity member = elementMap.getMember(node);
+        MemberEntity member = kElementMap.getMember(node);
         if (liveMemberUsage.containsKey(member)) {
           memberMap[name] = node;
         }
@@ -182,7 +183,7 @@ class KLibraryEnv {
     } else {
       setterMap = <String, ir.Member>{};
       _setterMap.forEach((String name, ir.Member node) {
-        MemberEntity member = elementMap.getMember(node);
+        MemberEntity member = kElementMap.getMember(node);
         if (liveMemberUsage.containsKey(member)) {
           setterMap[name] = node;
         }
@@ -251,11 +252,8 @@ abstract class KClassEnv {
   /// Ensures that all members have been computed for [cls].
   void ensureMembers(KernelToElementMap elementMap);
 
-  /// Return the [MemberEntity] for the member [name] in the class. If [setter]
+  /// Return the [MemberEntity] for the member [name] in the class.
-  /// is `true`, the setter or assignable field corresponding to [name] is
+  MemberEntity lookupMember(IrToElementMap elementMap, Name name);
-  /// returned.
-  MemberEntity lookupMember(IrToElementMap elementMap, String name,
-      {bool setter = false});
 
   /// Calls [f] for each member of [cls].
   void forEachMember(IrToElementMap elementMap, void f(MemberEntity member));
@@ -273,8 +271,13 @@ abstract class KClassEnv {
 
   /// Convert this [KClassEnv] to the corresponding [JClassEnv] containing only
   /// the members in [liveMembers].
-  JClassEnv convert(IrToElementMap elementMap,
+  ///
-      Map<MemberEntity, MemberUsage> liveMemberUsage);
+  /// [getJLibrary] returns the [LibraryEntity] in the J-model corresponding to
+  /// a [ir.Library] node.
+  JClassEnv convert(
+      IrToElementMap kElementMap,
+      Map<MemberEntity, MemberUsage> liveMemberUsage,
+      LibraryEntity Function(ir.Library library) getJLibrary);
 
   /// Returns `true` if [node] is a known member of this class.
   ///
@@ -299,8 +302,7 @@ class KClassEnvImpl implements KClassEnv {
   final ir.Class cls;
 
   Map<String, ir.Member> _constructorMap;
-  Map<String, ir.Member> _memberMap;
+  Map<Name, ir.Member> _memberMap;
-  Map<String, ir.Member> _setterMap;
   List<ir.Member> _members; // in declaration order.
   bool _isMixinApplicationWithMembers;
 
@@ -310,7 +312,7 @@ class KClassEnvImpl implements KClassEnv {
   KClassEnvImpl(this.cls);
 
   KClassEnvImpl.internal(this.cls, this._constructorMap, this._memberMap,
-      this._setterMap, this._members, this._isMixinApplicationWithMembers);
+      this._members, this._isMixinApplicationWithMembers);
 
   @override
   bool get isUnnamedMixinApplication => cls.isAnonymousMixin;
@@ -325,7 +327,6 @@ class KClassEnvImpl implements KClassEnv {
   bool checkHasMember(ir.Member node) {
     if (_memberMap == null) return false;
     return _memberMap.values.contains(node) ||
-        _setterMap.values.contains(node) ||
         _constructorMap.values.contains(node);
   }
 
@@ -337,8 +338,7 @@ class KClassEnvImpl implements KClassEnv {
   void _ensureMaps(KernelToElementMap elementMap) {
     if (_memberMap != null) return;
 
-    _memberMap = <String, ir.Member>{};
+    _memberMap = <Name, ir.Member>{};
-    _setterMap = <String, ir.Member>{};
     _constructorMap = <String, ir.Member>{};
     var members = <ir.Member>[];
     _isMixinApplicationWithMembers = false;
@@ -346,10 +346,10 @@ class KClassEnvImpl implements KClassEnv {
     void addField(ir.Field member, {bool includeStatic}) {
       if (!includeStatic && member.isStatic) return;
       if (isRedirectingFactoryField(member)) return;
-      var name = member.name.text;
+      var name = elementMap.getName(member.name);
       _memberMap[name] = member;
       if (member.hasSetter) {
-        _setterMap[name] = member;
+        _memberMap[name.setter] = member;
       }
       members.add(member);
     }
@@ -361,30 +361,18 @@ class KClassEnvImpl implements KClassEnv {
       if (memberIsIgnorable(member, cls: cls)) return;
       if (!includeStatic && member.isStatic) return;
       if (member.isNoSuchMethodForwarder) {
-        // TODO(sigmund): remove once #33732 is fixed.
+        if (!includeNoSuchMethodForwarders) {
-        if (!includeNoSuchMethodForwarders ||
-            member.name.isPrivate &&
-                member.name.libraryName != member.enclosingLibrary.reference) {
           return;
         }
       }
-      var name = member.name.text;
       if (member.kind == ir.ProcedureKind.Factory) {
         if (member.isRedirectingFactory) {
           // Don't include redirecting factories.
           return;
         }
-        _constructorMap[name] = member;
+        _constructorMap[member.name.text] = member;
-      } else if (member.kind == ir.ProcedureKind.Setter) {
-        _setterMap[name] = member;
-        members.add(member);
-        if (isFromMixinApplication) {
-          _isMixinApplicationWithMembers = true;
-        }
       } else {
-        assert(member.kind == ir.ProcedureKind.Method ||
+        var name = elementMap.getName(member.name, setter: member.isSetter);
-            member.kind == ir.ProcedureKind.Getter ||
-            member.kind == ir.ProcedureKind.Operator);
         _memberMap[name] = member;
         members.add(member);
         if (isFromMixinApplication) {
@@ -438,10 +426,9 @@ class KClassEnvImpl implements KClassEnv {
   }
 
   @override
-  MemberEntity lookupMember(IrToElementMap elementMap, String name,
+  MemberEntity lookupMember(IrToElementMap elementMap, Name name) {
-      {bool setter = false}) {
     _ensureMaps(elementMap);
-    ir.Member member = setter ? _setterMap[name] : _memberMap[name];
+    ir.Member member = _memberMap[name];
     return member != null ? elementMap.getMember(member) : null;
   }
 
@@ -480,57 +467,47 @@ class KClassEnvImpl implements KClassEnv {
   }
 
   @override
-  JClassEnv convert(IrToElementMap elementMap,
+  JClassEnv convert(
-      Map<MemberEntity, MemberUsage> liveMemberUsage) {
+      IrToElementMap kElementMap,
+      Map<MemberEntity, MemberUsage> liveMemberUsage,
+      LibraryEntity Function(ir.Library library) getJLibrary) {
     Map<String, ir.Member> constructorMap;
-    Map<String, ir.Member> memberMap;
+    Map<Name, ir.Member> memberMap;
-    Map<String, ir.Member> setterMap;
     List<ir.Member> members;
     if (_constructorMap == null) {
       constructorMap = const <String, ir.Member>{};
     } else {
       constructorMap = <String, ir.Member>{};
       _constructorMap.forEach((String name, ir.Member node) {
-        MemberEntity member = elementMap.getMember(node);
+        MemberEntity member = kElementMap.getMember(node);
         if (liveMemberUsage.containsKey(member)) {
           constructorMap[name] = node;
         }
       });
     }
     if (_memberMap == null) {
-      memberMap = const <String, ir.Member>{};
+      memberMap = const <Name, ir.Member>{};
     } else {
-      memberMap = <String, ir.Member>{};
+      memberMap = <Name, ir.Member>{};
-      _memberMap.forEach((String name, ir.Member node) {
+      _memberMap.forEach((Name name, ir.Member node) {
-        MemberEntity member = elementMap.getMember(node);
+        MemberEntity member = kElementMap.getMember(node);
         if (liveMemberUsage.containsKey(member)) {
           memberMap[name] = node;
         }
       });
     }
-    if (_setterMap == null) {
-      setterMap = const <String, ir.Member>{};
-    } else {
-      setterMap = <String, ir.Member>{};
-      _setterMap.forEach((String name, ir.Member node) {
-        MemberEntity member = elementMap.getMember(node);
-        if (liveMemberUsage.containsKey(member)) {
-          setterMap[name] = node;
-        }
-      });
-    }
     if (_members == null) {
       members = const <ir.Member>[];
     } else {
       members = <ir.Member>[];
       _members.forEach((ir.Member node) {
-        MemberEntity member = elementMap.getMember(node);
+        MemberEntity member = kElementMap.getMember(node);
         if (liveMemberUsage.containsKey(member)) {
           members.add(node);
         }
       });
     }
-    return JClassEnvImpl(cls, constructorMap, memberMap, setterMap, members,
+    return JClassEnvImpl(cls, constructorMap, memberMap, members,
         _isMixinApplicationWithMembers ?? false);
   }
 }

pkg/compiler/lib/src/kernel/kernel_impact.dart

@@ -831,8 +831,8 @@ class KernelImpactConverter implements ImpactRegistry {
       }
       ClassEntity? cls = type.element;
       while (cls != null) {
-        MemberEntity member =
+        MemberEntity member = elementMap.elementEnvironment
-            elementMap.elementEnvironment.lookupClassMember(cls, '==')!;
+            .lookupClassMember(cls, Names.EQUALS_NAME)!;
         if (member.isAbstract) {
           cls = elementMap.elementEnvironment.getSuperClass(cls);
         } else {

pkg/compiler/lib/src/kernel/kernel_strategy.dart

@@ -120,7 +120,7 @@ class KernelFrontendStrategy
         (_, MemberEntity member) {
       if (!member.isInstanceMember) return;
       MemberEntity interceptorMember = elementEnvironment
-          .lookupLocalClassMember(interceptorClass, member.name);
+          .lookupLocalClassMember(interceptorClass, member.memberName);
       // Interceptors must override all Object methods due to calling convention
       // differences.
       assert(

pkg/compiler/lib/src/kernel/kernel_world.dart

@@ -136,7 +136,7 @@ class KClosedWorld implements BuiltWorld, interfaces.KClosedWorld {
             .checkHasMember(elementMap.getMemberNode(member))) {
           throw SpannableAssertionFailure(
               member,
-              "Member $member is in the environment of its enclosing class"
+              "Member $member is not in the environment of its enclosing class"
               " ${member.enclosingClass}.");
         }
       }

pkg/compiler/lib/src/serialization/serialization.dart

@@ -12,6 +12,7 @@ import '../constants/values.dart';
 import '../deferred_load/output_unit.dart' show OutputUnit;
 import '../elements/entities.dart';
 import '../elements/indexed.dart';
+import '../elements/names.dart';
 import '../elements/types.dart';
 import '../inferrer/abstract_value_domain.dart';
 import '../ir/constants.dart';

pkg/compiler/lib/src/serialization/sink.dart

@@ -246,6 +246,26 @@ class DataSinkWriter {
     }
   }
 
+  /// Writes the [map] from [Name] to [V] values to this data sink, calling [f]
+  /// to write each value to the data sink. If [allowNull] is `true`, [map] is
+  /// allowed to be `null`.
+  ///
+  /// This is a convenience method to be used together with
+  /// [DataSourceReader.readNameMap].
+  void writeNameMap<V>(Map<Name, V>? map, void f(V value),
+      {bool allowNull = false}) {
+    if (map == null) {
+      assert(allowNull);
+      writeInt(0);
+    } else {
+      writeInt(map.length);
+      map.forEach((Name key, V value) {
+        writeMemberName(key);
+        f(value);
+      });
+    }
+  }
+
   /// Writes the string [values] to this data sink. If [allowNull] is `true`,
   /// [values] is allowed to be `null`.
   ///
@@ -386,6 +406,13 @@ class DataSinkWriter {
     writeValueOrNull(value.library, writeLibraryNode);
   }
 
+  /// Writes a [Name] to this data sink.
+  void writeMemberName(Name value) {
+    writeString(value.text);
+    writeValueOrNull(value.uri, writeUri);
+    writeBool(value.isSetter);
+  }
+
   /// Writes a kernel library dependency node [value] to this data sink.
   void writeLibraryDependencyNode(ir.LibraryDependency value) {
     final library = value.parent as ir.Library;

pkg/compiler/lib/src/serialization/source.dart

@@ -378,6 +378,24 @@ class DataSourceReader {
     return list;
   }
 
+  /// Reads a map from [Name] values to [V] values from this data source,
+  /// calling [f] to read each value from the data source. If [emptyAsNull] is
+  /// `true`, `null` is returned instead of an empty map.
+  ///
+  /// This is a convenience method to be used together with
+  /// [DataSinkWriter.writeNameMap].
+  Map<Name, V>? readNameMap<V>(V f(), {bool emptyAsNull = false}) {
+    int count = readInt();
+    if (count == 0 && emptyAsNull) return null;
+    Map<Name, V> map = {};
+    for (int i = 0; i < count; i++) {
+      Name key = readMemberName();
+      V value = f();
+      map[key] = value;
+    }
+    return map;
+  }
+
   /// Reads a map from string values to [V] values from this data source,
   /// calling [f] to read each value from the data source. If [emptyAsNull] is
   /// `true`, `null` is returned instead of an empty map.
@@ -537,6 +555,14 @@ class DataSourceReader {
     return ir.Name(text, library);
   }
 
+  /// Reads a [Name] from this data source.
+  Name readMemberName() {
+    String text = readString();
+    Uri? uri = readValueOrNull(readUri);
+    bool setter = readBool();
+    return Name(text, uri, isSetter: setter);
+  }
+
   /// Reads a kernel library dependency node from this data source.
   ir.LibraryDependency readLibraryDependencyNode() {
     ir.Library library = readLibraryNode();

pkg/compiler/lib/src/ssa/builder.dart

@@ -4285,7 +4285,7 @@ class KernelSsaGraphBuilder extends ir.Visitor<void> with ir.VisitorVoidMixin {
     Map<String, ir.Expression> namedArguments = {};
     int kind = _readIntLiteral(invocation.arguments.positional[4]);
 
-    Name memberName = Name(name, _currentFrame.member.library);
+    Name memberName = Name(name, _currentFrame.member.library.canonicalUri);
     Selector selector;
     switch (kind) {
       case invocationMirrorGetterKind:

pkg/compiler/lib/src/ssa/invoke_dynamic_specializers.dart

@@ -51,7 +51,8 @@ class InvokeDynamicSpecializer {
     Selector selector = instruction.selector;
     if (selector.name == name) return;
     instruction.selector = Selector.call(
-        Name(name, commonElements.interceptorsLibrary), selector.callStructure);
+        Name(name, commonElements.interceptorsLibrary.canonicalUri),
+        selector.callStructure);
   }
 
   constant_system.Operation operation() => null;

pkg/compiler/lib/src/ssa/optimize.dart

@@ -12,6 +12,7 @@ import '../common/tasks.dart' show Measurer, CompilerTask;
 import '../constants/constant_system.dart' as constant_system;
 import '../constants/values.dart';
 import '../elements/entities.dart';
+import '../elements/names.dart';
 import '../elements/types.dart';
 import '../inferrer/abstract_value_domain.dart';
 import '../inferrer/types.dart';
@@ -1181,8 +1182,8 @@ class SsaInstructionSimplifier extends HBaseVisitor
   }
 
   FieldEntity _indexFieldOfEnumClass(ClassEntity enumClass) {
-    MemberEntity member =
+    MemberEntity member = _closedWorld.elementEnvironment
-        _closedWorld.elementEnvironment.lookupClassMember(enumClass, 'index');
+        .lookupClassMember(enumClass, const PublicName('index'));
     if (member is FieldEntity) return member;
     throw StateError('$enumClass should have index field, found $member');
   }

pkg/compiler/lib/src/universe/selector.dart

@@ -63,8 +63,6 @@ class Selector {
 
   String get name => memberName.text;
 
-  LibraryEntity? get library => memberName.library;
-
   static bool isOperatorName(String name) {
     return instanceMethodOperatorNames.contains(name);
   }
@@ -198,22 +196,17 @@ class Selector {
   factory Selector.readFromDataSource(DataSourceReader source) {
     source.begin(tag);
     SelectorKind kind = source.readEnum(SelectorKind.values);
-    bool isSetter = source.readBool();
+    Name memberName = source.readMemberName();
-    LibraryEntity? library = source.readLibraryOrNull();
-    String text = source.readString();
     CallStructure callStructure = CallStructure.readFromDataSource(source);
     source.end(tag);
-    return Selector(
+    return Selector(kind, memberName, callStructure);
-        kind, Name(text, library, isSetter: isSetter), callStructure);
   }
 
   /// Serializes this [Selector] to [sink].
   void writeToDataSink(DataSinkWriter sink) {
     sink.begin(tag);
     sink.writeEnum(kind);
-    sink.writeBool(memberName.isSetter);
+    sink.writeMemberName(memberName);
-    sink.writeLibraryOrNull(memberName.library);
-    sink.writeString(memberName.text);
     callStructure.writeToDataSink(sink);
     sink.end(tag);
   }
@@ -244,9 +237,7 @@ class Selector {
 
   bool appliesUnnamed(MemberEntity element) {
     assert(name == element.name);
-    if (memberName.isPrivate && memberName.library != element.library) {
+    if (!memberName.matches(element.memberName)) {
-      // TODO(johnniwinther): Maybe this should be
-      // `memberName != element.memberName`.
       return false;
     }
     if (element.isSetter) return isSetter;

pkg/compiler/test/codegen/trust_type_annotations_test.dart

@@ -4,6 +4,8 @@
 
 // @dart = 2.7
 
+import 'package:compiler/src/compiler.dart';
+import 'package:compiler/src/elements/names.dart';
 import 'package:expect/expect.dart';
 import "package:async_helper/async_helper.dart";
 import 'package:compiler/src/commandline_options.dart';
@@ -56,7 +58,7 @@ void main() {
     var options = [Flags.omitImplicitChecks];
     var result = await runCompiler(
         memorySourceFiles: {'main.dart': TEST}, options: options);
-    var compiler = result.compiler;
+    Compiler compiler = result.compiler;
     var results = compiler.globalInference.resultsForTesting;
     var closedWorld = results.closedWorld;
     var elementEnvironment = closedWorld.elementEnvironment;
@@ -65,13 +67,15 @@ void main() {
         elementEnvironment.lookupClass(elementEnvironment.mainLibrary, "A");
 
     checkReturn(String name, TypeMask type) {
-      MemberEntity element = elementEnvironment.lookupClassMember(classA, name);
+      MemberEntity element =
+          elementEnvironment.lookupClassMember(classA, PublicName(name));
       var mask = results.resultOfMember(element).returnType;
       Expect.isTrue(type.containsMask(mask, closedWorld));
     }
 
     checkType(String name, type) {
-      MemberEntity element = elementEnvironment.lookupClassMember(classA, name);
+      MemberEntity element =
+          elementEnvironment.lookupClassMember(classA, PublicName(name));
       Expect.isTrue(
           type.containsMask(results.resultOfMember(element).type, closedWorld));
     }

pkg/compiler/test/end_to_end/dill_loader_test.dart

@@ -4,6 +4,8 @@
 
 // @dart = 2.7
 
+import 'package:compiler/src/elements/names.dart';
+
 import '../helpers/memory_compiler.dart';
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/common/elements.dart';
@@ -60,7 +62,7 @@ main() {
     Expect.isNotNull(library);
     ClassEntity clss = environment.lookupClass(library, 'ListLiteralTest');
     Expect.isNotNull(clss);
-    var member = environment.lookupClassMember(clss, 'testMain');
+    var member = environment.lookupClassMember(clss, PublicName('testMain'));
     Expect.isNotNull(member);
   });
 }

pkg/compiler/test/end_to_end/modular_loader_test.dart

@@ -4,6 +4,8 @@
 
 // @dart = 2.7
 
+import 'package:compiler/src/elements/names.dart';
+
 import '../helpers/memory_compiler.dart';
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/common/elements.dart';
@@ -61,7 +63,7 @@ main() {
     Expect.isNotNull(library);
     ClassEntity clss = environment.lookupClass(library, 'B1');
     Expect.isNotNull(clss);
-    var member = environment.lookupClassMember(clss, 'foo');
+    var member = environment.lookupClassMember(clss, PublicName('foo'));
     Expect.isNotNull(member);
   });
 }

pkg/compiler/test/equivalence/id_equivalence_helper.dart

@@ -14,6 +14,7 @@ import 'package:compiler/src/common/elements.dart';
 import 'package:compiler/src/commandline_options.dart';
 import 'package:compiler/src/compiler.dart';
 import 'package:compiler/src/elements/entities.dart';
+import 'package:compiler/src/elements/names.dart';
 import 'package:compiler/src/kernel/element_map.dart';
 import 'package:compiler/src/kernel/kernel_strategy.dart';
 import 'package:expect/expect.dart';
@@ -325,7 +326,8 @@ Future<CompiledData<T>> computeData<T>(String name, Uri entryPoint,
       MemberEntity member;
       if (id.className != null) {
         ClassEntity cls = getGlobalClass(id.className);
-        member = elementEnvironment.lookupClassMember(cls, id.memberName);
+        member = elementEnvironment.lookupClassMember(
+            cls, Name(id.memberName, cls.library.canonicalUri));
         member ??= elementEnvironment.lookupConstructor(cls, id.memberName);
         Expect.isNotNull(
             member, "Global member '$member' not found in class $cls.");
@@ -552,8 +554,8 @@ Spannable computeSpannable(
         print("No class '${id.className}' in $mainUri.");
         return NO_LOCATION_SPANNABLE;
       }
-      MemberEntity member = elementEnvironment
+      MemberEntity member = elementEnvironment.lookupClassMember(
-          .lookupClassMember(cls, memberName, setter: isSetter);
+          cls, Name(memberName, cls.library.canonicalUri, isSetter: isSetter));
       if (member == null) {
         ConstructorEntity constructor =
             elementEnvironment.lookupConstructor(cls, memberName);

pkg/compiler/test/generic_methods/generic_method_test.dart

@@ -9,6 +9,7 @@ import 'package:compiler/src/commandline_options.dart';
 import 'package:compiler/src/common/elements.dart';
 import 'package:compiler/src/compiler.dart';
 import 'package:compiler/src/elements/entities.dart';
+import 'package:compiler/src/elements/names.dart';
 import 'package:compiler/src/js/js.dart' as js;
 import 'package:compiler/src/js_model/js_strategy.dart';
 import 'package:compiler/src/world.dart';
@@ -194,7 +195,8 @@ main(List<String> args) {
         ClassEntity cls = elementEnvironment.lookupClass(
             elementEnvironment.mainLibrary, className);
         Expect.isNotNull(cls, "Class '$className' not found.");
-        method = elementEnvironment.lookupClassMember(cls, methodName);
+        method = elementEnvironment.lookupClassMember(
+            cls, Name(methodName, cls.library.canonicalUri));
         Expect.isNotNull(method, "Method '$methodName' not found in $cls.");
       } else {
         method = elementEnvironment.lookupLibraryMember(

pkg/compiler/test/helpers/element_lookup.dart

@@ -6,6 +6,7 @@
 
 import 'package:compiler/src/common/elements.dart' show JElementEnvironment;
 import 'package:compiler/src/elements/entities.dart';
+import 'package:compiler/src/elements/names.dart';
 import 'package:compiler/src/elements/types.dart';
 import 'package:compiler/src/world.dart' show JClosedWorld;
 
@@ -45,8 +46,8 @@ MemberEntity findClassMember(
   JElementEnvironment elementEnvironment = closedWorld.elementEnvironment;
   ClassEntity cls = findClass(closedWorld, className);
   assert(cls != null, "Class '$className' not found.");
-  MemberEntity member =
+  MemberEntity member = elementEnvironment.lookupClassMember(
-      elementEnvironment.lookupClassMember(cls, memberName, setter: isSetter);
+      cls, Name(memberName, cls.library.canonicalUri, isSetter: isSetter));
   if (member == null && !isSetter) {
     member = elementEnvironment.lookupConstructor(cls, memberName);
   }

pkg/compiler/test/helpers/program_lookup.dart

@@ -7,6 +7,7 @@
 import 'package:compiler/src/common/elements.dart';
 import 'package:compiler/src/deferred_load/output_unit.dart' show OutputUnit;
 import 'package:compiler/src/elements/entities.dart';
+import 'package:compiler/src/elements/names.dart';
 import 'package:compiler/src/js/js.dart' as js;
 import 'package:compiler/src/js_backend/namer.dart';
 import 'package:compiler/src/js_emitter/model.dart';
@@ -29,7 +30,8 @@ MemberEntity lookupMember(JElementEnvironment elementEnvironment, String name) {
     ClassEntity cls = elementEnvironment.lookupClass(
         elementEnvironment.mainLibrary, className);
     Expect.isNotNull(cls, "No class '$className' found in the main library.");
-    member = elementEnvironment.lookupClassMember(cls, name);
+    member = elementEnvironment.lookupClassMember(
+        cls, Name(name, cls.library.canonicalUri));
     member ??= elementEnvironment.lookupConstructor(cls, name);
     Expect.isNotNull(member, "No member '$name' found in $cls");
   } else {

pkg/compiler/test/helpers/type_test_helper.dart

@@ -7,6 +7,7 @@
 library type_test_helper;
 
 import 'dart:async';
+import 'package:compiler/src/elements/names.dart';
 import 'package:expect/expect.dart';
 import 'package:compiler/src/common/elements.dart';
 import 'package:compiler/src/commandline_options.dart';
@@ -136,7 +137,8 @@ class TypeEnvironment {
 
   MemberEntity _getMember(String name, [ClassEntity cls]) {
     if (cls != null) {
-      return elementEnvironment.lookupLocalClassMember(cls, name);
+      return elementEnvironment.lookupLocalClassMember(
+          cls, Name(name, cls.library.canonicalUri));
     } else {
       LibraryEntity mainLibrary = elementEnvironment.mainLibrary;
       return elementEnvironment.lookupLibraryMember(mainLibrary, name);

pkg/compiler/test/model/constant_value_test.dart

@@ -7,6 +7,7 @@
 library dart2js.constants.values.test;
 
 import 'package:async_helper/async_helper.dart';
+import 'package:compiler/src/elements/names.dart';
 import 'package:expect/expect.dart';
 import 'package:compiler/src/elements/entities.dart';
 import 'package:compiler/src/elements/types.dart';
@@ -30,8 +31,10 @@ void main() {
     """);
     ClassEntity C = env.getClass('C');
     InterfaceType C_raw = env.elementEnvironment.getRawType(C);
-    FieldEntity field1 = env.elementEnvironment.lookupClassMember(C, 'field1');
+    FieldEntity field1 =
-    FieldEntity field2 = env.elementEnvironment.lookupClassMember(C, 'field2');
+        env.elementEnvironment.lookupClassMember(C, PublicName('field1'));
+    FieldEntity field2 =
+        env.elementEnvironment.lookupClassMember(C, PublicName('field2'));
     ConstructedConstantValue value1 = new ConstructedConstantValue(C_raw, {
       field1: new IntConstantValue(BigInt.zero),
       field2: new IntConstantValue(BigInt.one),

pkg/compiler/test/model/enqueuer_test.dart

@@ -194,7 +194,7 @@ main() {}
     ClassEntity cls = elementEnvironment.lookupClass(
         elementEnvironment.mainLibrary, className);
     Selector selector = new Selector.call(
-        new Name(methodName, elementEnvironment.mainLibrary),
+        new Name(methodName, elementEnvironment.mainLibrary.canonicalUri),
         CallStructure.NO_ARGS);
     WorldImpact impact = new WorldImpactBuilderImpl()
       ..registerDynamicUse(

pkg/compiler/test/model/forwarding_stub_test.dart

@@ -8,6 +8,7 @@ import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/common/elements.dart';
 import 'package:compiler/src/compiler.dart';
 import 'package:compiler/src/elements/entities.dart';
+import 'package:compiler/src/elements/names.dart';
 import 'package:compiler/src/world.dart';
 import 'package:expect/expect.dart';
 import '../helpers/memory_compiler.dart';
@@ -37,7 +38,8 @@ main() {
         elementEnvironment.lookupClass(elementEnvironment.mainLibrary, 'Class');
     ClassEntity mixin =
         elementEnvironment.lookupClass(elementEnvironment.mainLibrary, 'Mixin');
-    FunctionEntity method = elementEnvironment.lookupClassMember(cls, 'method');
+    FunctionEntity method =
+        elementEnvironment.lookupClassMember(cls, PublicName('method'));
     Expect.isNotNull(method);
     Expect.equals(mixin, method.enclosingClass);
     Expect.isFalse(method.isAbstract);

pkg/compiler/test/model/no_such_method_enabled_test.dart

@@ -6,6 +6,7 @@
 
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/common/elements.dart';
+import 'package:compiler/src/common/names.dart';
 import 'package:compiler/src/compiler.dart';
 import 'package:compiler/src/elements/entities.dart';
 import 'package:compiler/src/js_backend/no_such_method_registry.dart';
@@ -261,7 +262,8 @@ checkTest(Compiler compiler, NoSuchMethodTest test) {
       compiler.frontendStrategy.noSuchMethodRegistry;
   var resolver = registry.internalResolverForTesting;
   FunctionEntity ObjectNSM = frontendEnvironment.lookupClassMember(
-      compiler.frontendStrategy.commonElements.objectClass, 'noSuchMethod');
+      compiler.frontendStrategy.commonElements.objectClass,
+      Names.noSuchMethod_);
   JClosedWorld backendClosedWorld = compiler.backendClosedWorldForTesting;
   ElementEnvironment backendEnvironment = backendClosedWorld.elementEnvironment;
   NoSuchMethodData data = backendClosedWorld.noSuchMethodData;
@@ -272,7 +274,7 @@ checkTest(Compiler compiler, NoSuchMethodTest test) {
         frontendEnvironment.mainLibrary, info.className);
     Expect.isNotNull(cls, "Class ${info.className} not found.");
     FunctionEntity noSuchMethod =
-        frontendEnvironment.lookupClassMember(cls, 'noSuchMethod');
+        frontendEnvironment.lookupClassMember(cls, Names.noSuchMethod_);
     Expect.isNotNull(noSuchMethod, "noSuchMethod not found in $cls.");
 
     if (info.superClassName == null) {
@@ -282,8 +284,8 @@ checkTest(Compiler compiler, NoSuchMethodTest test) {
           frontendEnvironment.mainLibrary, info.superClassName);
       Expect.isNotNull(
           superclass, "Superclass ${info.superClassName} not found.");
-      FunctionEntity superNoSuchMethod =
+      FunctionEntity superNoSuchMethod = frontendEnvironment.lookupClassMember(
-          frontendEnvironment.lookupClassMember(superclass, 'noSuchMethod');
+          superclass, Names.noSuchMethod_);
       Expect.isNotNull(
           superNoSuchMethod, "noSuchMethod not found in $superclass.");
       Expect.equals(
@@ -309,8 +311,8 @@ checkTest(Compiler compiler, NoSuchMethodTest test) {
     ClassEntity frontendClass = frontendEnvironment.lookupClass(
         frontendEnvironment.mainLibrary, info.className);
     Expect.isNotNull(frontendClass, "Class ${info.className} not found.");
-    FunctionEntity frontendNoSuchMethod =
+    FunctionEntity frontendNoSuchMethod = frontendEnvironment.lookupClassMember(
-        frontendEnvironment.lookupClassMember(frontendClass, 'noSuchMethod');
+        frontendClass, Names.noSuchMethod_);
     Expect.isNotNull(
         frontendNoSuchMethod, "noSuchMethod not found in $frontendClass.");
 
@@ -331,7 +333,7 @@ checkTest(Compiler compiler, NoSuchMethodTest test) {
         backendEnvironment.mainLibrary, info.className);
     Expect.isNotNull(backendClass, "Class ${info.className} not found.");
     FunctionEntity backendNoSuchMethod =
-        backendEnvironment.lookupClassMember(backendClass, 'noSuchMethod');
+        backendEnvironment.lookupClassMember(backendClass, Names.noSuchMethod_);
     Expect.isNotNull(
         backendNoSuchMethod, "noSuchMethod not found in $backendClass.");
 

pkg/compiler/test/model/type_substitution_test.dart

@@ -6,6 +6,7 @@
 
 library type_substitution_test;
 
+import 'package:compiler/src/elements/names.dart';
 import 'package:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/commandline_options.dart';
@@ -17,7 +18,8 @@ import '../helpers/type_test_helper.dart';
 DartType getType(ElementEnvironment elementEnvironment, String name) {
   ClassEntity cls =
       elementEnvironment.lookupClass(elementEnvironment.mainLibrary, 'Class');
-  FunctionEntity element = elementEnvironment.lookupClassMember(cls, name);
+  FunctionEntity element = elementEnvironment.lookupClassMember(
+      cls, Name(name, cls.library.canonicalUri));
   Expect.isNotNull(element);
   FunctionType type = elementEnvironment.getFunctionType(element);
 

pkg/compiler/test/rti/rti_need_test_helper.dart

@@ -12,6 +12,7 @@ import 'package:compiler/src/common.dart';
 import 'package:compiler/src/common/elements.dart';
 import 'package:compiler/src/compiler.dart';
 import 'package:compiler/src/elements/entities.dart';
+import 'package:compiler/src/elements/names.dart';
 import 'package:compiler/src/elements/types.dart';
 import 'package:compiler/src/js_backend/runtime_types_resolution.dart';
 import 'package:compiler/src/js_model/js_world.dart';
@@ -288,8 +289,9 @@ abstract class IrMixin implements ComputeValueMixin {
             frontendClass, backendMember.name);
       } else {
         return elementEnvironment.lookupClassMember(
-            frontendClass, backendMember.name,
+            frontendClass,
-            setter: backendMember.isSetter);
+            Name(backendMember.name, frontendClass.library.canonicalUri,
+                isSetter: backendMember.isSetter));
       }
     }
     return elementEnvironment.lookupLibraryMember(

pkg/compiler/test/sourcemaps/name_test.dart

@@ -7,6 +7,7 @@
 library source_map_name_test;
 
 import 'package:async_helper/async_helper.dart';
+import 'package:compiler/src/elements/names.dart';
 import 'package:expect/expect.dart';
 import 'package:compiler/src/commandline_options.dart';
 import 'package:compiler/src/common/elements.dart' show JElementEnvironment;
@@ -101,7 +102,8 @@ main() {
         ClassEntity cls = env.lookupClass(mainApp, clsName);
         Expect.isNotNull(cls, "Class '$clsName' not found.");
         var subname = name.substring(dotPosition + 1);
-        element = env.lookupLocalClassMember(cls, subname) ??
+        element = env.lookupLocalClassMember(
+                cls, Name(subname, cls.library.canonicalUri)) ??
             env.lookupConstructor(cls, subname);
       } else {
         element = env.lookupLibraryMember(mainApp, name);

sdk/bin/dart2js.bat

@@ -39,7 +39,7 @@ if %DART_ROOT:~-1%==\ set DART_ROOT=%DART_ROOT:~0,-1%
 
 set DART2JS=%DART_ROOT%\pkg\compiler\lib\src\dart2js.dart
 
-"%DART%" "--packages=%DART_ROOT%\.packages" %EXTRA_VM_OPTIONS% "%DART2JS%" %EXTRA_OPTIONS% %*
+"%DART%" "--packages=%DART_ROOT%\.dart_tool\package_config.json" %EXTRA_VM_OPTIONS% "%DART2JS%" %EXTRA_OPTIONS% %*
 
 endlocal
 

tests/web/regress/private_names_lib1.dart

@@ -0,0 +1,75 @@
+// Copyright (c) 2022, 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.
+
+import 'private_names_lib2.dart';
+
+export 'private_names_lib2.dart' show DoubleLinkedQueueEntry;
+
+abstract class _DoubleLinkedQueueEntry<E> {
+  _DoubleLinkedQueueEntry<E>? _previousLink;
+  _DoubleLinkedQueueEntry<E>? _nextLink;
+
+  void _link(
+      _DoubleLinkedQueueEntry<E>? previous, _DoubleLinkedQueueEntry<E>? next) {
+    _nextLink = next;
+    _previousLink = previous;
+    previous?._nextLink = this;
+    next?._previousLink = this;
+  }
+
+  _DoubleLinkedQueueElement<E>? _asNonSentinelEntry();
+
+  void _prepend(E element, DoubleLinkedQueue<E>? queue) {
+    _DoubleLinkedQueueElement<E>(element, queue)._link(_previousLink, this);
+  }
+}
+
+class _DoubleLinkedQueueElement<E> extends _DoubleLinkedQueueEntry<E>
+    implements DoubleLinkedQueueEntry<E> {
+  DoubleLinkedQueue<E>? _queue;
+  E element;
+
+  _DoubleLinkedQueueElement(this.element, this._queue);
+
+  void prepend(E e) {
+    _prepend(e, _queue);
+    _queue?._elementCount++;
+  }
+
+  _DoubleLinkedQueueElement<E> _asNonSentinelEntry() => this;
+}
+
+class _DoubleLinkedQueueSentinel<E> extends _DoubleLinkedQueueEntry<E> {
+  _DoubleLinkedQueueSentinel() {
+    _previousLink = this;
+    _nextLink = this;
+  }
+
+  Null _asNonSentinelEntry() => null;
+}
+
+class DoubleLinkedQueue<E> /*extends Iterable<E> implements Queue<E>*/ {
+  final _DoubleLinkedQueueSentinel<E> _sentinel =
+      _DoubleLinkedQueueSentinel<E>();
+
+  int _elementCount = 0;
+
+  DoubleLinkedQueue();
+
+  factory DoubleLinkedQueue.from(Iterable<dynamic> elements) {
+    DoubleLinkedQueue<E> list = DoubleLinkedQueue<E>();
+    for (final e in elements) {
+      list.addLast(e as E);
+    }
+    return list;
+  }
+
+  void addLast(E value) {
+    _sentinel._prepend(value, this);
+    _elementCount++;
+  }
+
+  DoubleLinkedQueueEntry<E>? firstEntry() =>
+      _sentinel._nextLink!._asNonSentinelEntry();
+}

tests/web/regress/private_names_lib2.dart

@@ -0,0 +1,24 @@
+// Copyright (c) 2022, 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 DoubleLinkedQueueEntry<E> {
+  DoubleLinkedQueueEntry<E>? _previousLink;
+  DoubleLinkedQueueEntry<E>? _nextLink;
+
+  E element;
+
+  DoubleLinkedQueueEntry(this.element);
+
+  void _link(
+      DoubleLinkedQueueEntry<E>? previous, DoubleLinkedQueueEntry<E>? next) {
+    _nextLink = next;
+    _previousLink = previous;
+    previous?._nextLink = this;
+    next?._previousLink = this;
+  }
+
+  void prepend(E e) {
+    DoubleLinkedQueueEntry<E>(e)._link(_previousLink, this);
+  }
+}

tests/web/regress/private_names_test.dart

@@ -0,0 +1,31 @@
+// Copyright (c) 2022, 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.
+
+// Derived from lib/collection/queue_test which showed in error in the
+// of private names in dart2js.
+
+library queue.test;
+
+import 'private_names_lib1.dart';
+
+class DoubleLinkedQueueTest {
+  void testMain() {
+    testQueueElements();
+  }
+
+  void testQueueElements() {
+    DoubleLinkedQueue<int> queue1 = new DoubleLinkedQueue<int>.from([1, 2, 3]);
+    var firstEntry = queue1.firstEntry()!;
+    firstEntry.prepend(4);
+  }
+}
+
+void linkEntryTest() {
+  var entry = new DoubleLinkedQueueEntry(42);
+}
+
+main() {
+  new DoubleLinkedQueueTest().testMain();
+  linkEntryTest();
+}

tests/web_2/regress/private_names_lib1.dart

@@ -0,0 +1,75 @@
+// Copyright (c) 2022, 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.
+
+import 'private_names_lib2.dart';
+
+export 'private_names_lib2.dart' show DoubleLinkedQueueEntry;
+
+abstract class _DoubleLinkedQueueEntry<E> {
+  _DoubleLinkedQueueEntry<E>? _previousLink;
+  _DoubleLinkedQueueEntry<E>? _nextLink;
+
+  void _link(
+      _DoubleLinkedQueueEntry<E>? previous, _DoubleLinkedQueueEntry<E>? next) {
+    _nextLink = next;
+    _previousLink = previous;
+    previous?._nextLink = this;
+    next?._previousLink = this;
+  }
+
+  _DoubleLinkedQueueElement<E>? _asNonSentinelEntry();
+
+  void _prepend(E element, DoubleLinkedQueue<E>? queue) {
+    _DoubleLinkedQueueElement<E>(element, queue)._link(_previousLink, this);
+  }
+}
+
+class _DoubleLinkedQueueElement<E> extends _DoubleLinkedQueueEntry<E>
+    implements DoubleLinkedQueueEntry<E> {
+  DoubleLinkedQueue<E>? _queue;
+  E element;
+
+  _DoubleLinkedQueueElement(this.element, this._queue);
+
+  void prepend(E e) {
+    _prepend(e, _queue);
+    _queue?._elementCount++;
+  }
+
+  _DoubleLinkedQueueElement<E> _asNonSentinelEntry() => this;
+}
+
+class _DoubleLinkedQueueSentinel<E> extends _DoubleLinkedQueueEntry<E> {
+  _DoubleLinkedQueueSentinel() {
+    _previousLink = this;
+    _nextLink = this;
+  }
+
+  Null _asNonSentinelEntry() => null;
+}
+
+class DoubleLinkedQueue<E> /*extends Iterable<E> implements Queue<E>*/ {
+  final _DoubleLinkedQueueSentinel<E> _sentinel =
+      _DoubleLinkedQueueSentinel<E>();
+
+  int _elementCount = 0;
+
+  DoubleLinkedQueue();
+
+  factory DoubleLinkedQueue.from(Iterable<dynamic> elements) {
+    DoubleLinkedQueue<E> list = DoubleLinkedQueue<E>();
+    for (final e in elements) {
+      list.addLast(e as E);
+    }
+    return list;
+  }
+
+  void addLast(E value) {
+    _sentinel._prepend(value, this);
+    _elementCount++;
+  }
+
+  DoubleLinkedQueueEntry<E>? firstEntry() =>
+      _sentinel._nextLink!._asNonSentinelEntry();
+}

tests/web_2/regress/private_names_lib2.dart

@@ -0,0 +1,24 @@
+// Copyright (c) 2022, 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 DoubleLinkedQueueEntry<E> {
+  DoubleLinkedQueueEntry<E>? _previousLink;
+  DoubleLinkedQueueEntry<E>? _nextLink;
+
+  E element;
+
+  DoubleLinkedQueueEntry(this.element);
+
+  void _link(
+      DoubleLinkedQueueEntry<E>? previous, DoubleLinkedQueueEntry<E>? next) {
+    _nextLink = next;
+    _previousLink = previous;
+    previous?._nextLink = this;
+    next?._previousLink = this;
+  }
+
+  void prepend(E e) {
+    DoubleLinkedQueueEntry<E>(e)._link(_previousLink, this);
+  }
+}

tests/web_2/regress/private_names_test.dart

@@ -0,0 +1,33 @@
+// Copyright (c) 2022, 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.
+
+// Derived from lib_2/collection/queue_test which showed in error in the
+// of private names in dart2js.
+
+// @dart = 2.9
+
+library queue.test;
+
+import 'private_names_lib1.dart';
+
+class DoubleLinkedQueueTest {
+  void testMain() {
+    testQueueElements();
+  }
+
+  void testQueueElements() {
+    DoubleLinkedQueue<int> queue1 = new DoubleLinkedQueue<int>.from([1, 2, 3]);
+    var firstEntry = queue1.firstEntry();
+    firstEntry.prepend(4);
+  }
+}
+
+void linkEntryTest() {
+  var entry = new DoubleLinkedQueueEntry(42);
+}
+
+main() {
+  new DoubleLinkedQueueTest().testMain();
+  linkEntryTest();
+}