Add strong mode type checking pass.

lib/type_checker.dart

+// Copyright (c) 2016, 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.
+library kernel.type_checker;
+
+import 'ast.dart';
+import 'class_hierarchy.dart';
+import 'core_types.dart';
+import 'type_algebra.dart';
+import 'type_environment.dart';
+
+/// Performs strong-mode type checking on the kernel IR.
+///
+/// A concrete subclass of [TypeChecker] must implement [checkAssignable] and
+/// [fail] in order to deal with subtyping requirements and error handling.
+abstract class TypeChecker {
+  final CoreTypes coreTypes;
+  final ClassHierarchy hierarchy;
+  TypeEnvironment environment;
+
+  TypeChecker(this.coreTypes, this.hierarchy) {
+    environment = new TypeEnvironment(coreTypes, hierarchy);
+  }
+
+  void checkProgram(Program program) {
+    for (var library in program.libraries) {
+      if (library.importUri.scheme == 'dart') continue;
+      for (var class_ in library.classes) {
+        hierarchy.forEachOverridePair(class_,
+            (Member ownMember, Member superMember, bool isSetter) {
+          checkOverride(class_, ownMember, superMember, isSetter);
+        });
+      }
+    }
+    var visitor = new TypeCheckingVisitor(this, environment);
+    for (var library in program.libraries) {
+      if (library.importUri.scheme == 'dart') continue;
+      for (var class_ in library.classes) {
+        environment.thisType = class_.thisType;
+        for (var field in class_.fields) {
+          visitor.visitField(field);
+        }
+        for (var constructor in class_.constructors) {
+          visitor.visitConstructor(constructor);
+        }
+        for (var procedure in class_.procedures) {
+          visitor.visitProcedure(procedure);
+        }
+      }
+      environment.thisType = null;
+      for (var procedure in library.procedures) {
+        visitor.visitProcedure(procedure);
+      }
+      for (var field in library.fields) {
+        visitor.visitField(field);
+      }
+    }
+  }
+
+  DartType getterType(Class host, Member member) {
+    var hostType = hierarchy.getClassAsInstanceOf(host, member.enclosingClass);
+    var substitution = Substitution.fromSupertype(hostType);
+    return substitution.substituteType(member.getterType);
+  }
+
+  DartType setterType(Class host, Member member) {
+    var hostType = hierarchy.getClassAsInstanceOf(host, member.enclosingClass);
+    var substitution = Substitution.fromSupertype(hostType);
+    return substitution.substituteType(member.setterType, contravariant: true);
+  }
+
+  void checkOverride(
+      Class host, Member ownMember, Member superMember, bool isSetter) {
+    if (isSetter) {
+      checkAssignable(ownMember, setterType(host, superMember),
+          setterType(host, ownMember));
+    } else {
+      checkAssignable(ownMember, getterType(host, ownMember),
+          getterType(host, superMember));
+    }
+  }
+
+  /// Check that [from] is a subtype of [to].
+  ///
+  /// [where] is an AST node indicating roughly where the check is required.
+  void checkAssignable(TreeNode where, DartType from, DartType to);
+
+  /// Indicates that type checking failed.
+  void fail(TreeNode where, String message);
+}
+
+class TypeCheckingVisitor
+    implements
+        ExpressionVisitor<DartType>,
+        StatementVisitor<Null>,
+        MemberVisitor<Null>,
+        InitializerVisitor<Null> {
+  final TypeChecker checker;
+  final TypeEnvironment environment;
+
+  CoreTypes get coreTypes => environment.coreTypes;
+  ClassHierarchy get hierarchy => environment.hierarchy;
+  Class get currentClass => environment.thisType.classNode;
+
+  TypeCheckingVisitor(this.checker, this.environment);
+
+  void checkAssignable(TreeNode where, DartType from, DartType to) {
+    checker.checkAssignable(where, from, to);
+  }
+
+  void checkAssignableExpression(Expression from, DartType to) {
+    checker.checkAssignable(from, visitExpression(from), to);
+  }
+
+  void fail(TreeNode node, String message) {
+    checker.fail(node, message);
+  }
+
+  DartType visitExpression(Expression node) => node.accept(this);
+
+  void visitStatement(Statement node) {
+    node.accept(this);
+  }
+
+  void visitInitializer(Initializer node) {
+    node.accept(this);
+  }
+
+  defaultMember(Member node) => throw 'Unused';
+
+  DartType defaultBasicLiteral(BasicLiteral node) {
+    return defaultExpression(node);
+  }
+
+  DartType defaultExpression(Expression node) {
+    throw 'Unexpected expression ${node.runtimeType}';
+  }
+
+  defaultStatement(Statement node) {
+    throw 'Unexpected statement ${node.runtimeType}';
+  }
+
+  defaultInitializer(Initializer node) {
+    throw 'Unexpected initializer ${node.runtimeType}';
+  }
+
+  visitField(Field node) {
+    if (node.initializer != null) {
+      checkAssignableExpression(node.initializer, node.type);
+    }
+  }
+
+  visitConstructor(Constructor node) {
+    environment.returnType = null;
+    environment.yieldType = null;
+    node.initializers.forEach(visitInitializer);
+    handleFunctionNode(node.function);
+  }
+
+  visitProcedure(Procedure node) {
+    environment.returnType = node.function.returnType;
+    environment.yieldType = _getYieldType(node.function);
+    handleFunctionNode(node.function);
+  }
+
+  void handleFunctionNode(FunctionNode node) {
+    node.positionalParameters
+        .skip(node.requiredParameterCount)
+        .forEach(handleOptionalParameter);
+    node.namedParameters.forEach(handleOptionalParameter);
+    if (node.body != null) {
+      visitStatement(node.body);
+    }
+  }
+
+  void handleNestedFunctionNode(FunctionNode node) {
+    var oldReturn = environment.returnType;
+    var oldYield = environment.yieldType;
+    environment.returnType = node.returnType;
+    environment.yieldType = _getYieldType(node);
+    handleFunctionNode(node);
+    environment.returnType = oldReturn;
+    environment.yieldType = oldYield;
+  }
+
+  void handleOptionalParameter(VariableDeclaration parameter) {
+    if (parameter.initializer != null) {
+      checkAssignableExpression(parameter.initializer, parameter.type);
+    }
+  }
+
+  Substitution getReceiverType(
+      TreeNode access, Expression receiver, Member member) {
+    var type = visitExpression(receiver);
+    Class superclass = member.enclosingClass;
+    if (superclass.supertype == null) {
+      return Substitution.empty; // Members on Object are always accessible.
+    }
+    while (type is TypeParameterType) {
+      type = (type as TypeParameterType).parameter.bound;
+    }
+    if (type is BottomType) {
+      // The bottom type is a subtype of all types, so it should be allowed.
+      return Substitution.bottomForClass(superclass);
+    }
+    if (type is InterfaceType) {
+      // The receiver type should implement the interface declaring the member.
+      var upcastType = hierarchy.getTypeAsInstanceOf(type, superclass);
+      if (upcastType != null) {
+        return Substitution.fromInterfaceType(upcastType);
+      }
+    }
+    if (type is FunctionType && superclass == coreTypes.functionClass) {
+      assert(type.typeParameters.isEmpty);
+      return Substitution.empty;
+    }
+    // Note that we do not allow 'dynamic' here.  Dynamic calls should not
+    // have a declared interface target.
+    fail(access, '$member is not accessible on a receiver of type $type');
+    return Substitution.bottomForClass(superclass); // Continue type checking.
+  }
+
+  Substitution getSuperReceiverType(Member member) {
+    return Substitution.fromSupertype(
+        hierarchy.getClassAsInstanceOf(currentClass, member.enclosingClass));
+  }
+
+  DartType handleCall(Arguments arguments, FunctionNode function,
+      {Substitution receiver: Substitution.empty,
+      List<TypeParameter> typeParameters}) {
+    typeParameters ??= function.typeParameters;
+    if (arguments.positional.length < function.requiredParameterCount) {
+      fail(arguments, 'Too few positional arguments');
+      return const BottomType();
+    }
+    if (arguments.positional.length > function.positionalParameters.length) {
+      fail(arguments, 'Too many positional arguments');
+      return const BottomType();
+    }
+    if (arguments.types.length != typeParameters.length) {
+      fail(arguments, 'Wrong number of type arguments');
+      return const BottomType();
+    }
+    var instantiation = Substitution.fromPairs(typeParameters, arguments.types);
+    var substitution = Substitution.combine(receiver, instantiation);
+    for (int i = 0; i < typeParameters.length; ++i) {
+      var argument = arguments.types[i];
+      var bound = substitution.substituteType(typeParameters[i].bound);
+      checkAssignable(arguments, argument, bound);
+    }
+    for (int i = 0; i < arguments.positional.length; ++i) {
+      var expectedType = substitution.substituteType(
+          function.positionalParameters[i].type,
+          contravariant: true);
+      checkAssignableExpression(arguments.positional[i], expectedType);
+    }
+    for (int i = 0; i < arguments.named.length; ++i) {
+      var argument = arguments.named[i];
+      bool found = false;
+      for (int j = 0; j < function.namedParameters.length; ++j) {
+        if (argument.name == function.namedParameters[j].name) {
+          var expectedType = substitution.substituteType(
+              function.namedParameters[j].type,
+              contravariant: true);
+          checkAssignableExpression(argument.value, expectedType);
+          found = true;
+          break;
+        }
+      }
+      if (!found) {
+        fail(argument.value, 'Unexpected named parameter: ${argument.name}');
+        return const BottomType();
+      }
+    }
+    return substitution.substituteType(function.returnType);
+  }
+
+  DartType _getYieldType(FunctionNode function) {
+    switch (function.asyncMarker) {
+      case AsyncMarker.Sync:
+      case AsyncMarker.Async:
+        return null;
+
+      case AsyncMarker.SyncStar:
+      case AsyncMarker.AsyncStar:
+        Class container = function.asyncMarker == AsyncMarker.SyncStar
+            ? coreTypes.iterableClass
+            : coreTypes.streamClass;
+        DartType returnType = function.returnType;
+        if (returnType is InterfaceType && returnType.classNode == container) {
+          return returnType.typeArguments.single;
+        }
+        return const DynamicType();
+
+      case AsyncMarker.SyncYielding:
+        return function.returnType;
+
+      default:
+        throw 'Unexpected async marker: ${function.asyncMarker}';
+    }
+  }
+
+  @override
+  DartType visitAsExpression(AsExpression node) {
+    visitExpression(node.operand);
+    return node.type;
+  }
+
+  @override
+  DartType visitAwaitExpression(AwaitExpression node) {
+    return environment.unfutureType(visitExpression(node.operand));
+  }
+
+  @override
+  DartType visitBoolLiteral(BoolLiteral node) {
+    return environment.boolType;
+  }
+
+  @override
+  DartType visitConditionalExpression(ConditionalExpression node) {
+    checkAssignableExpression(node.condition, environment.boolType);
+    if (node.staticType == null) {
+      var thenType = visitExpression(node.then);
+      var otherwiseType = visitExpression(node.otherwise);
+      if (thenType is BottomType) return otherwiseType;
+      if (otherwiseType is BottomType) return thenType;
+      return const DynamicType();
+    } else {
+      checkAssignableExpression(node.then, node.staticType);
+      checkAssignableExpression(node.otherwise, node.staticType);
+      return node.staticType;
+    }
+  }
+
+  @override
+  DartType visitConstructorInvocation(ConstructorInvocation node) {
+    Constructor target = node.target;
+    Arguments arguments = node.arguments;
+    Class class_ = target.enclosingClass;
+    handleCall(arguments, target.function,
+        typeParameters: class_.typeParameters);
+    return new InterfaceType(target.enclosingClass, arguments.types);
+  }
+
+  @override
+  DartType visitDirectMethodInvocation(DirectMethodInvocation node) {
+    return handleCall(node.arguments, node.target.function,
+        receiver: getReceiverType(node, node.receiver, node.target));
+  }
+
+  @override
+  DartType visitDirectPropertyGet(DirectPropertyGet node) {
+    var receiver = getReceiverType(node, node.receiver, node.target);
+    return receiver.substituteType(node.target.getterType);
+  }
+
+  @override
+  DartType visitDirectPropertySet(DirectPropertySet node) {
+    var receiver = getReceiverType(node, node.receiver, node.target);
+    var value = visitExpression(node.value);
+    checkAssignable(node, value,
+        receiver.substituteType(node.target.setterType, contravariant: true));
+    return value;
+  }
+
+  @override
+  DartType visitDoubleLiteral(DoubleLiteral node) {
+    return environment.doubleType;
+  }
+
+  @override
+  DartType visitFunctionExpression(FunctionExpression node) {
+    handleNestedFunctionNode(node.function);
+    return node.function.functionType;
+  }
+
+  @override
+  DartType visitIntLiteral(IntLiteral node) {
+    return environment.intType;
+  }
+
+  @override
+  DartType visitInvalidExpression(InvalidExpression node) {
+    return const BottomType();
+  }
+
+  @override
+  DartType visitIsExpression(IsExpression node) {
+    visitExpression(node.operand);
+    return environment.boolType;
+  }
+
+  @override
+  DartType visitLet(Let node) {
+    var value = visitExpression(node.variable.initializer);
+    if (node.variable.type is DynamicType) {
+      node.variable.type = value;
+    }
+    return visitExpression(node.body);
+  }
+
+  @override
+  DartType visitListLiteral(ListLiteral node) {
+    for (var item in node.expressions) {
+      checkAssignableExpression(item, node.typeArgument);
+    }
+    return environment.literalListType(node.typeArgument);
+  }
+
+  @override
+  DartType visitLogicalExpression(LogicalExpression node) {
+    checkAssignableExpression(node.left, environment.boolType);
+    checkAssignableExpression(node.right, environment.boolType);
+    return environment.boolType;
+  }
+
+  @override
+  DartType visitMapLiteral(MapLiteral node) {
+    for (var entry in node.entries) {
+      checkAssignableExpression(entry.key, node.keyType);
+      checkAssignableExpression(entry.value, node.valueType);
+    }
+    return environment.literalMapType(node.keyType, node.valueType);
+  }
+
+  DartType handleDynamicCall(DartType receiver, Arguments arguments) {
+    arguments.positional.forEach(visitExpression);
+    arguments.named.forEach((NamedExpression n) => visitExpression(n.value));
+    return const DynamicType();
+  }
+
+  DartType handleFunctionCall(
+      TreeNode access, FunctionType function, Arguments arguments) {
+    if (function.requiredParameterCount > arguments.positional.length) {
+      fail(access, 'Too few positional arguments');
+      return const BottomType();
+    }
+    if (function.positionalParameters.length < arguments.positional.length) {
+      fail(access, 'Too many positional arguments');
+      return const BottomType();
+    }
+    if (function.typeParameters.length != arguments.types.length) {
+      fail(access, 'Wrong number of type arguments');
+      return const BottomType();
+    }
+    var instantiation =
+        Substitution.fromPairs(function.typeParameters, arguments.types);
+    for (int i = 0; i < arguments.positional.length; ++i) {
+      var expectedType = instantiation.substituteType(
+          function.positionalParameters[i],
+          contravariant: true);
+      checkAssignableExpression(arguments.positional[i], expectedType);
+    }
+    for (int i = 0; i < arguments.named.length; ++i) {
+      var argument = arguments.named[i];
+      var expectedType = function.namedParameters[argument.name];
+      if (expectedType == null) {
+        fail(argument.value, 'Unexpected named parameter: ${argument.name}');
+      } else {
+        checkAssignableExpression(argument.value,
+            instantiation.substituteType(expectedType, contravariant: true));
+      }
+    }
+    return instantiation.substituteType(function.returnType);
+  }
+
+  @override
+  DartType visitMethodInvocation(MethodInvocation node) {
+    var target = node.interfaceTarget;
+    if (target == null) {
+      var receiver = visitExpression(node.receiver);
+      return (node.name.name == 'call' && receiver is FunctionType)
+          ? handleFunctionCall(node, receiver, node.arguments)
+          : handleDynamicCall(receiver, node.arguments);
+    } else if (environment.isOverloadedArithmeticOperator(target)) {
+      assert(node.arguments.positional.length == 1);
+      var receiver = visitExpression(node.receiver);
+      var argument = visitExpression(node.arguments.positional[0]);
+      return environment.getTypeOfOverloadedArithmetic(receiver, argument);
+    } else {
+      return handleCall(node.arguments, target.function,
+          receiver: getReceiverType(node, node.receiver, node.interfaceTarget));
+    }
+  }
+
+  @override
+  DartType visitPropertyGet(PropertyGet node) {
+    if (node.interfaceTarget == null) {
+      visitExpression(node.receiver);
+      return const DynamicType();
+    } else {
+      var receiver = getReceiverType(node, node.receiver, node.interfaceTarget);
+      return receiver.substituteType(node.interfaceTarget.getterType);
+    }
+  }
+
+  @override
+  DartType visitPropertySet(PropertySet node) {
+    var value = visitExpression(node.value);
+    if (node.interfaceTarget != null) {
+      var receiver = getReceiverType(node, node.receiver, node.interfaceTarget);
+      checkAssignable(
+          node.value,
+          value,
+          receiver.substituteType(node.interfaceTarget.setterType,
+              contravariant: true));
+    } else {
+      visitExpression(node.receiver);
+    }
+    return value;
+  }
+
+  @override
+  DartType visitNot(Not node) {
+    visitExpression(node.operand);
+    return environment.boolType;
+  }
+
+  @override
+  DartType visitNullLiteral(NullLiteral node) {
+    return const BottomType();
+  }
+
+  @override
+  DartType visitRethrow(Rethrow node) {
+    return const BottomType();
+  }
+
+  @override
+  DartType visitStaticGet(StaticGet node) {
+    return node.target.getterType;
+  }
+
+  @override
+  DartType visitStaticInvocation(StaticInvocation node) {
+    return handleCall(node.arguments, node.target.function);
+  }
+
+  @override
+  DartType visitStaticSet(StaticSet node) {
+    var value = visitExpression(node.value);
+    checkAssignable(node.value, value, node.target.setterType);
+    return value;
+  }
+
+  @override
+  DartType visitStringConcatenation(StringConcatenation node) {
+    node.expressions.forEach(visitExpression);
+    return environment.stringType;
+  }
+
+  @override
+  DartType visitStringLiteral(StringLiteral node) {
+    return environment.stringType;
+  }
+
+  @override
+  DartType visitSuperMethodInvocation(SuperMethodInvocation node) {
+    if (node.interfaceTarget == null) {
+      return handleDynamicCall(environment.thisType, node.arguments);
+    } else {
+      return handleCall(node.arguments, node.interfaceTarget.function,
+          receiver: getSuperReceiverType(node.interfaceTarget));
+    }
+  }
+
+  @override
+  DartType visitSuperPropertyGet(SuperPropertyGet node) {
+    if (node.interfaceTarget == null) {
+      return const DynamicType();
+    } else {
+      var receiver = getSuperReceiverType(node.interfaceTarget);
+      return receiver.substituteType(node.interfaceTarget.getterType);
+    }
+  }
+
+  @override
+  DartType visitSuperPropertySet(SuperPropertySet node) {
+    var value = visitExpression(node.value);
+    if (node.interfaceTarget != null) {
+      var receiver = getSuperReceiverType(node.interfaceTarget);
+      checkAssignable(
+          node.value,
+          value,
+          receiver.substituteType(node.interfaceTarget.setterType,
+              contravariant: true));
+    }
+    return value;
+  }
+
+  @override
+  DartType visitSymbolLiteral(SymbolLiteral node) {
+    return environment.symbolType;
+  }
+
+  @override
+  DartType visitThisExpression(ThisExpression node) {
+    return environment.thisType;
+  }
+
+  @override
+  DartType visitThrow(Throw node) {
+    visitExpression(node.expression);
+    return const BottomType();
+  }
+
+  @override
+  DartType visitTypeLiteral(TypeLiteral node) {
+    return environment.typeType;
+  }
+
+  @override
+  DartType visitVariableGet(VariableGet node) {
+    return node.promotedType ?? node.variable.type;
+  }
+
+  @override
+  DartType visitVariableSet(VariableSet node) {
+    var value = visitExpression(node.value);
+    checkAssignable(node.value, value, node.variable.type);
+    return value;
+  }
+
+  @override
+  visitAssertStatement(AssertStatement node) {
+    visitExpression(node.condition);
+    if (node.message != null) {
+      visitExpression(node.message);
+    }
+  }
+
+  @override
+  visitBlock(Block node) {
+    node.statements.forEach(visitStatement);
+  }
+
+  @override
+  visitBreakStatement(BreakStatement node) {}
+
+  @override
+  visitContinueSwitchStatement(ContinueSwitchStatement node) {}
+
+  @override
+  visitDoStatement(DoStatement node) {
+    visitStatement(node.body);
+    checkAssignableExpression(node.condition, environment.boolType);
+  }
+
+  @override
+  visitEmptyStatement(EmptyStatement node) {}
+
+  @override
+  visitExpressionStatement(ExpressionStatement node) {
+    visitExpression(node.expression);
+  }
+
+  @override
+  visitForInStatement(ForInStatement node) {
+    var iterable = visitExpression(node.iterable);
+    // TODO(asgerf): Store interface targets on for-in loops or desugar them,
+    // instead of doing the ad-hoc resolution here.
+    if (node.isAsync) {
+      checkAssignable(node, getStreamElementType(iterable), node.variable.type);
+    } else {
+      checkAssignable(
+          node, getIterableElementType(iterable), node.variable.type);
+    }
+    visitStatement(node.body);
+  }
+
+  static final Name iteratorName = new Name('iterator');
+  static final Name nextName = new Name('next');
+
+  DartType getIterableElementType(DartType iterable) {
+    if (iterable is InterfaceType) {
+      var iteratorGetter =
+          hierarchy.getInterfaceMember(iterable.classNode, iteratorName);
+      if (iteratorGetter == null) return const DynamicType();
+      var iteratorType = Substitution
+          .fromInterfaceType(iterable)
+          .substituteType(iteratorGetter.getterType);
+      if (iteratorType is InterfaceType) {
+        var nextGetter =
+            hierarchy.getInterfaceMember(iteratorType.classNode, nextName);
+        if (nextGetter == null) return const DynamicType();
+        return Substitution
+            .fromInterfaceType(iteratorType)
+            .substituteType(nextGetter.getterType);
+      }
+    }
+    return const DynamicType();
+  }
+
+  DartType getStreamElementType(DartType stream) {
+    if (stream is InterfaceType) {
+      var asStream =
+          hierarchy.getTypeAsInstanceOf(stream, coreTypes.streamClass);
+      if (asStream == null) return const DynamicType();
+      return asStream.typeArguments.single;
+    }
+    return const DynamicType();
+  }
+
+  @override
+  visitForStatement(ForStatement node) {
+    node.variables.forEach(visitVariableDeclaration);
+    if (node.condition != null) {
+      checkAssignableExpression(node.condition, environment.boolType);
+    }
+    node.updates.forEach(visitExpression);
+    visitStatement(node.body);
+  }
+
+  @override
+  visitFunctionDeclaration(FunctionDeclaration node) {
+    handleNestedFunctionNode(node.function);
+  }
+
+  @override
+  visitIfStatement(IfStatement node) {
+    checkAssignableExpression(node.condition, environment.boolType);
+    visitStatement(node.then);
+    if (node.otherwise != null) {
+      visitStatement(node.otherwise);
+    }
+  }
+
+  @override
+  visitInvalidStatement(InvalidStatement node) {}
+
+  @override
+  visitLabeledStatement(LabeledStatement node) {
+    visitStatement(node.body);
+  }
+
+  @override
+  visitReturnStatement(ReturnStatement node) {
+    if (node.expression != null) {
+      if (environment.returnType == null) {
+        fail(node, 'Return of a value from void method');
+      } else {
+        checkAssignableExpression(node.expression, environment.returnType);
+      }
+    }
+  }
+
+  @override
+  visitSwitchStatement(SwitchStatement node) {
+    visitExpression(node.expression);
+    for (var switchCase in node.cases) {
+      switchCase.expressions.forEach(visitExpression);
+      visitStatement(switchCase.body);
+    }
+  }
+
+  @override
+  visitTryCatch(TryCatch node) {
+    visitStatement(node.body);
+    for (var catchClause in node.catches) {
+      visitStatement(catchClause.body);
+    }
+  }
+
+  @override
+  visitTryFinally(TryFinally node) {
+    visitStatement(node.body);
+    visitStatement(node.finalizer);
+  }
+
+  @override
+  visitVariableDeclaration(VariableDeclaration node) {
+    if (node.initializer != null) {
+      checkAssignableExpression(node.initializer, node.type);
+    }
+  }
+
+  @override
+  visitWhileStatement(WhileStatement node) {
+    checkAssignableExpression(node.condition, environment.boolType);
+    visitStatement(node.body);
+  }
+
+  @override
+  visitYieldStatement(YieldStatement node) {
+    checkAssignableExpression(node.expression, environment.yieldType);
+  }
+
+  @override
+  visitFieldInitializer(FieldInitializer node) {
+    checkAssignableExpression(node.value, node.field.type);
+  }
+
+  @override
+  visitRedirectingInitializer(RedirectingInitializer node) {
+    handleCall(node.arguments, node.target.function,
+        typeParameters: const <TypeParameter>[]);
+  }
+
+  @override
+  visitSuperInitializer(SuperInitializer node) {
+    handleCall(node.arguments, node.target.function,
+        typeParameters: const <TypeParameter>[]);
+  }
+
+  @override
+  visitLocalInitializer(LocalInitializer node) {
+    visitVariableDeclaration(node.variable);
+  }
+
+  @override
+  visitInvalidInitializer(InvalidInitializer node) {}
+}