pkg/front_end/lib/src/fasta/kernel/body_builder.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 fasta.body_builder;

import 'dart:core' hide MapEntry;

import '../constant_context.dart' show ConstantContext;

import '../fasta_codes.dart' as fasta;

import '../fasta_codes.dart' show LocatedMessage, Message, noLength, Template;

import '../messages.dart' as messages show getLocationFromUri;

import '../modifier.dart' show Modifier, constMask, covariantMask, finalMask;

import '../names.dart'
    show callName, emptyName, indexGetName, indexSetName, minusName, plusName;

import '../parser.dart'
    show
        Assert,
        Parser,
        FormalParameterKind,
        IdentifierContext,
        MemberKind,
        lengthForToken,
        lengthOfSpan,
        offsetForToken,
        optional;

import '../problems.dart' show unexpected, unhandled, unsupported;

import '../quote.dart'
    show
        Quote,
        analyzeQuote,
        unescape,
        unescapeFirstStringPart,
        unescapeLastStringPart,
        unescapeString;

import '../scanner.dart' show Token;

import '../scanner/token.dart' show isBinaryOperator, isMinusOperator;

import '../scope.dart' show ProblemBuilder;

import '../severity.dart' show Severity;

import '../source/scope_listener.dart'
    show
        FixedNullableList,
        GrowableList,
        JumpTargetKind,
        NullValue,
        ParserRecovery,
        ScopeListener;

import '../type_inference/type_inferrer.dart' show TypeInferrer;

import '../type_inference/type_promotion.dart'
    show TypePromoter, TypePromotionFact, TypePromotionScope;

import 'constness.dart' show Constness;

import 'expression_generator.dart'
    show
        DelayedAssignment,
        DelayedPostfixIncrement,
        Generator,
        IncompleteErrorGenerator,
        IncompletePropertyAccessGenerator,
        IncompleteSendGenerator,
        IndexedAccessGenerator,
        LoadLibraryGenerator,
        ParenthesizedExpressionGenerator,
        ParserErrorGenerator,
        PrefixUseGenerator,
        ReadOnlyAccessGenerator,
        SendAccessGenerator,
        StaticAccessGenerator,
        SuperIndexedAccessGenerator,
        ThisAccessGenerator,
        ThisPropertyAccessGenerator,
        TypeUseGenerator,
        UnlinkedGenerator,
        UnresolvedNameGenerator,
        VariableUseGenerator,
        buildIsNull;

import 'expression_generator_helper.dart' show ExpressionGeneratorHelper;

import 'forest.dart' show Forest;

import 'redirecting_factory_body.dart'
    show
        RedirectingFactoryBody,
        RedirectionTarget,
        getRedirectingFactoryBody,
        getRedirectionTarget,
        isRedirectingFactory;

import 'kernel_api.dart';

import 'kernel_ast_api.dart';

import 'kernel_builder.dart';

import 'type_algorithms.dart' show calculateBounds;

// TODO(ahe): Remove this and ensure all nodes have a location.
const noLocation = null;

abstract class BodyBuilder extends ScopeListener<JumpTarget>
    implements ExpressionGeneratorHelper {
  // TODO(ahe): Rename [library] to 'part'.
  @override
  final KernelLibraryBuilder library;

  final ModifierBuilder member;

  final KernelClassBuilder classBuilder;

  final ClassHierarchy hierarchy;

  @override
  final CoreTypes coreTypes;

  final bool isInstanceMember;

  final Scope enclosingScope;

  final bool enableNative;

  final bool stringExpectedAfterNative;

  /// Whether to ignore an unresolved reference to `main` within the body of
  /// `_getMainClosure` when compiling the current library.
  ///
  /// This as a temporary workaround. The standalone VM and flutter have
  /// special logic to resolve `main` in `_getMainClosure`, this flag is used to
  /// ignore that reference to `main`, but only on libraries where we expect to
  /// see it (today that is dart:_builtin and dart:ui).
  ///
  // TODO(ahe,sigmund): remove when the VM gets rid of the special rule, see
  // https://github.com/dart-lang/sdk/issues/28989.
  final bool ignoreMainInGetMainClosure;

  // TODO(ahe): Consider renaming [uri] to 'partUri'.
  @override
  final Uri uri;

  final TypeInferrer _typeInferrer;

  @override
  final TypePromoter typePromoter;

  /// Only used when [member] is a constructor. It tracks if an implicit super
  /// initializer is needed.
  ///
  /// An implicit super initializer isn't needed
  ///
  /// 1. if the current class is Object,
  /// 2. if there is an explicit super initializer,
  /// 3. if there is a redirecting (this) initializer, or
  /// 4. if a compile-time error prevented us from generating code for an
  ///    initializer. This avoids cascading errors.
  bool needsImplicitSuperInitializer;

  Scope formalParameterScope;

  /// This is set to true when we start parsing an initializer. We use this to
  /// find the correct scope for initializers like in this example:
  ///
  ///     class C {
  ///       final x;
  ///       C(x) : x = x;
  ///     }
  ///
  /// When parsing this initializer `x = x`, `x` must be resolved in two
  /// different scopes. The first `x` must be resolved in the class' scope, the
  /// second in the formal parameter scope.
  bool inInitializer = false;

  bool inFieldInitializer = false;

  bool inCatchClause = false;

  bool inCatchBlock = false;

  int functionNestingLevel = 0;

  Statement problemInLoopOrSwitch;

  Scope switchScope;

  CloneVisitor cloner;

  ConstantContext constantContext = ConstantContext.none;

  UnresolvedType<KernelTypeBuilder> currentLocalVariableType;

  // Using non-null value to initialize this field based on performance advice
  // from VM engineers. TODO(ahe): Does this still apply?
  int currentLocalVariableModifiers = -1;

  /// If non-null, records instance fields which have already been initialized
  /// and where that was.
  Map<String, int> initializedFields;

  /// List of built redirecting factory invocations.  The targets of the
  /// invocations are to be resolved in a separate step.
  final List<Expression> redirectingFactoryInvocations = <Expression>[];

  BodyBuilder(
      this.library,
      this.member,
      this.enclosingScope,
      this.formalParameterScope,
      this.hierarchy,
      this.coreTypes,
      this.classBuilder,
      this.isInstanceMember,
      this.uri,
      this._typeInferrer)
      : enableNative =
            library.loader.target.backendTarget.enableNative(library.uri),
        stringExpectedAfterNative =
            library.loader.target.backendTarget.nativeExtensionExpectsString,
        ignoreMainInGetMainClosure = library.uri.scheme == 'dart' &&
            (library.uri.path == "_builtin" || library.uri.path == "ui"),
        needsImplicitSuperInitializer =
            coreTypes?.objectClass != classBuilder?.cls,
        typePromoter = _typeInferrer?.typePromoter,
        super(enclosingScope);

  BodyBuilder.withParents(KernelFieldBuilder field, KernelLibraryBuilder part,
      KernelClassBuilder classBuilder, TypeInferrer typeInferrer)
      : this(
            part,
            field,
            classBuilder?.scope ?? field.library.scope,
            null,
            part.loader.hierarchy,
            part.loader.coreTypes,
            classBuilder,
            field.isInstanceMember,
            field.fileUri,
            typeInferrer);

  BodyBuilder.forField(KernelFieldBuilder field, TypeInferrer typeInferrer)
      : this.withParents(
            field,
            field.parent is KernelClassBuilder
                ? field.parent.parent
                : field.parent,
            field.parent is KernelClassBuilder ? field.parent : null,
            typeInferrer);

  bool get inConstructor {
    return functionNestingLevel == 0 && member is KernelConstructorBuilder;
  }

  bool get isInstanceContext {
    return isInstanceMember || member is KernelConstructorBuilder;
  }

  TypeEnvironment get typeEnvironment => _typeInferrer?.typeSchemaEnvironment;

  @override
  void push(Object node) {
    if (node is DartType) {
      unhandled("DartType", "push", -1, uri);
    }
    inInitializer = false;
    super.push(node);
  }

  Expression popForValue() => toValue(pop());

  Expression popForEffect() => toEffect(pop());

  Expression popForValueIfNotNull(Object value) {
    return value == null ? null : popForValue();
  }

  @override
  Expression toValue(Object node) {
    if (node is Generator) {
      return node.buildSimpleRead();
    } else if (node is Expression) {
      return node;
    } else if (node is SuperInitializer) {
      return buildProblem(
          fasta.messageSuperAsExpression, node.fileOffset, noLength);
    } else if (node is ProblemBuilder) {
      return buildProblem(node.message, node.charOffset, noLength);
    } else {
      return unhandled("${node.runtimeType}", "toValue", -1, uri);
    }
  }

  Expression toEffect(Object node) {
    if (node is Generator) return node.buildForEffect();
    return toValue(node);
  }

  List<Expression> popListForValue(int n) {
    List<Expression> list =
        new List<Expression>.filled(n, null, growable: true);
    for (int i = n - 1; i >= 0; i--) {
      list[i] = popForValue();
    }
    return list;
  }

  List<Expression> popListForEffect(int n) {
    List<Expression> list =
        new List<Expression>.filled(n, null, growable: true);
    for (int i = n - 1; i >= 0; i--) {
      list[i] = popForEffect();
    }
    return list;
  }

  Statement popBlock(int count, Token openBrace, Token closeBrace) {
    return forest.block(
        openBrace,
        const GrowableList<Statement>().pop(stack, count) ?? <Statement>[],
        closeBrace);
  }

  Statement popStatementIfNotNull(Object value) {
    return value == null ? null : popStatement();
  }

  Statement popStatement() => forest.wrapVariables(pop());

  void enterSwitchScope() {
    push(switchScope ?? NullValue.SwitchScope);
    switchScope = scope;
  }

  void exitSwitchScope() {
    Scope outerSwitchScope = pop();
    if (switchScope.unclaimedForwardDeclarations != null) {
      switchScope.unclaimedForwardDeclarations
          .forEach((String name, Declaration declaration) {
        if (outerSwitchScope == null) {
          JumpTarget target = declaration;
          for (Statement statement in target.users) {
            statement.parent.replaceChild(
                statement,
                wrapInProblemStatement(statement,
                    fasta.templateLabelNotFound.withArguments(name)));
          }
        } else {
          outerSwitchScope.forwardDeclareLabel(name, declaration);
        }
      });
    }
    switchScope = outerSwitchScope;
  }

  void wrapVariableInitializerInError(
      VariableDeclaration variable,
      Template<Message Function(String name)> template,
      List<LocatedMessage> context) {
    String name = variable.name;
    int offset = variable.fileOffset;
    Message message = template.withArguments(name);
    if (variable.initializer == null) {
      variable.initializer =
          buildProblem(message, offset, name.length, context: context)
            ..parent = variable;
    } else {
      variable.initializer = wrapInLocatedProblem(
          variable.initializer, message.withLocation(uri, offset, name.length),
          context: context)
        ..parent = variable;
    }
  }

  void declareVariable(VariableDeclaration variable, Scope scope) {
    String name = variable.name;
    Declaration existing = scope.local[name];
    if (existing != null) {
      // This reports an error for duplicated declarations in the same scope:
      // `{ var x; var x; }`
      wrapVariableInitializerInError(
          variable, fasta.templateDuplicatedDeclaration, <LocatedMessage>[
        fasta.templateDuplicatedDeclarationCause
            .withArguments(name)
            .withLocation(uri, existing.charOffset, name.length)
      ]);
      return;
    }
    LocatedMessage context = scope.declare(
        variable.name,
        new KernelVariableBuilder(
            variable, member ?? classBuilder ?? library, uri),
        uri);
    if (context != null) {
      // This case is different from the above error. In this case, the problem
      // is using `x` before it's declared: `{ var x; { print(x); var x;
      // }}`. In this case, we want two errors, the `x` in `print(x)` and the
      // second (or innermost declaration) of `x`.
      wrapVariableInitializerInError(
          variable,
          fasta.templateDuplicatedNamePreviouslyUsed,
          <LocatedMessage>[context]);
    }
  }

  @override
  JumpTarget createJumpTarget(JumpTargetKind kind, int charOffset) {
    return new JumpTarget(kind, functionNestingLevel, member, charOffset);
  }

  @override
  void beginMetadata(Token token) {
    debugEvent("beginMetadata");
    super.push(constantContext);
    constantContext = ConstantContext.inferred;
  }

  @override
  void endMetadata(Token beginToken, Token periodBeforeName, Token endToken) {
    debugEvent("Metadata");
    Arguments arguments = pop();
    pushQualifiedReference(beginToken.next, periodBeforeName);
    if (arguments != null) {
      push(arguments);
      buildConstructorReferenceInvocation(
          beginToken.next, beginToken.offset, Constness.explicitConst);
      push(popForValue());
    } else {
      pop(); // Name last identifier
      String name = pop();
      pop(); // Type arguments (ignored, already reported by parser).
      Object expression = pop();
      if (expression is Identifier) {
        Identifier identifier = expression;
        expression = new UnresolvedNameGenerator(
            this,
            deprecated_extractToken(identifier),
            new Name(identifier.name, library.library));
      }
      if (name?.isNotEmpty ?? false) {
        Token period = periodBeforeName ?? beginToken.next.next;
        Generator generator = expression;
        expression = generator.buildPropertyAccess(
            new IncompletePropertyAccessGenerator(
                this, period.next, new Name(name, library.library)),
            period.next.offset,
            false);
      }

      ConstantContext savedConstantContext = pop();
      if (expression is! StaticAccessGenerator) {
        push(wrapInProblem(
            toValue(expression), fasta.messageExpressionNotMetadata, noLength));
      } else {
        push(toValue(expression));
      }
      constantContext = savedConstantContext;
    }
  }

  @override
  void endMetadataStar(int count) {
    debugEvent("MetadataStar");
    if (count == 0) {
      push(NullValue.Metadata);
    } else {
      push(const GrowableList<Expression>().pop(stack, count) ??
          NullValue.Metadata /* Ignore parser recovery */);
    }
  }

  @override
  void endTopLevelFields(Token staticToken, Token covariantToken,
      Token varFinalOrConst, int count, Token beginToken, Token endToken) {
    debugEvent("TopLevelFields");
    push(count);
  }

  @override
  void endFields(Token staticToken, Token covariantToken, Token varFinalOrConst,
      int count, Token beginToken, Token endToken) {
    debugEvent("Fields");
    push(count);
  }

  @override
  void finishFields() {
    debugEvent("finishFields");
    int count = pop();
    List<FieldBuilder<Object>> fields = <FieldBuilder<Object>>[];
    for (int i = 0; i < count; i++) {
      Expression initializer = pop();
      Identifier identifier = pop();
      String name = identifier.name;
      Declaration declaration;
      if (classBuilder != null) {
        declaration = classBuilder[name];
      } else {
        declaration = library[name];
      }
      FieldBuilder<Object> field;
      if (declaration.isField && declaration.next == null) {
        field = declaration;
      } else {
        continue;
      }
      fields.add(field);
      if (initializer != null) {
        if (field.next != null) {
          // Duplicate definition. The field might not be the correct one,
          // so we skip inference of the initializer.
          // Error reporting and recovery is handled elsewhere.
        } else {
          field.initializer = initializer;
          _typeInferrer.inferFieldInitializer(
              this,
              field.hasTypeInferredFromInitializer ? null : field.builtType,
              initializer);
        }
      }
    }
    {
      // TODO(ahe): The type we compute here may be different from what is
      // computed in the outline phase. We should make sure that the outline
      // phase computes the same type. See
      // pkg/front_end/testcases/regress/issue_32200.dart for an example where
      // not calling [buildDartType] leads to a missing compile-time
      // error. Also, notice that the type of the problematic field isn't
      // `invalid-type`.
      buildDartType(pop()); // Type.
    }
    List<Expression> annotations = pop();
    if (annotations != null) {
      _typeInferrer.inferMetadata(this, annotations);
      Field field = fields.first.target;
      // The first (and often only field) will not get a clone.
      annotations.forEach((annotation) => field.addAnnotation(annotation));
      for (int i = 1; i < fields.length; i++) {
        // We have to clone the annotations on the remaining fields.
        field = fields[i].target;
        cloner ??= new CloneVisitor();
        for (Expression annotation in annotations) {
          field.addAnnotation(cloner.clone(annotation));
        }
      }
    }

    resolveRedirectingFactoryTargets();
  }

  @override
  void endMember() {
    debugEvent("Member");
  }

  @override
  void endBlockFunctionBody(int count, Token openBrace, Token closeBrace) {
    debugEvent("BlockFunctionBody");
    if (openBrace == null) {
      assert(count == 0);
      push(NullValue.Block);
    } else {
      Statement block = popBlock(count, openBrace, closeBrace);
      exitLocalScope();
      push(block);
    }
  }

  void prepareInitializers() {
    ProcedureBuilder<TypeBuilder> member = this.member;
    scope = member.computeFormalParameterInitializerScope(scope);
    if (member is KernelConstructorBuilder) {
      if (member.isConst &&
          (classBuilder.cls.superclass?.isMixinApplication ?? false)) {
        addProblem(fasta.messageConstConstructorInSubclassOfMixinApplication,
            member.charOffset, member.name.length);
      }
      if (member.formals != null) {
        for (KernelFormalParameterBuilder formal in member.formals) {
          if (formal.hasThis) {
            Initializer initializer;
            if (member.isExternal) {
              initializer = buildInvalidInitializer(
                  buildProblem(
                          fasta.messageExternalConstructorWithFieldInitializers,
                          formal.charOffset,
                          formal.name.length)
                      .desugared,
                  formal.charOffset);
            } else {
              initializer = buildFieldInitializer(true, formal.name,
                  formal.charOffset, new VariableGet(formal.declaration),
                  formalType: formal.declaration.type);
            }
            member.addInitializer(initializer, this);
          }
        }
      }
    }
  }

  @override
  void handleNoInitializers() {
    debugEvent("NoInitializers");
    if (functionNestingLevel == 0) {
      prepareInitializers();
      scope = formalParameterScope;
    }
  }

  @override
  void beginInitializers(Token token) {
    debugEvent("beginInitializers");
    if (functionNestingLevel == 0) {
      prepareInitializers();
    }
  }

  @override
  void endInitializers(int count, Token beginToken, Token endToken) {
    debugEvent("Initializers");
    if (functionNestingLevel == 0) {
      scope = formalParameterScope;
    }
  }

  @override
  void beginInitializer(Token token) {
    debugEvent("beginInitializer");
    inInitializer = true;
    inFieldInitializer = true;
  }

  @override
  void endInitializer(Token token) {
    debugEvent("endInitializer");
    inFieldInitializer = false;
    assert(!inInitializer);
    final member = this.member;
    Object node = pop();
    Initializer initializer;
    if (node is Initializer) {
      initializer = node;
    } else if (node is Generator) {
      initializer = node.buildFieldInitializer(initializedFields);
    } else if (node is ConstructorInvocation) {
      initializer = buildSuperInitializer(
          false, node.target, node.arguments, token.charOffset);
    } else {
      Expression value = toValue(node);
      if (!forest.isThrow(node)) {
        value =
            wrapInProblem(value, fasta.messageExpectedAnInitializer, noLength);
      }
      initializer = buildInvalidInitializer(node, token.charOffset);
    }
    _typeInferrer.inferInitializer(this, initializer);
    if (member is KernelConstructorBuilder && !member.isExternal) {
      member.addInitializer(initializer, this);
    } else {
      addProblem(
          fasta.templateInitializerOutsideConstructor
              .withArguments(member.name),
          token.charOffset,
          member.name.length);
    }
  }

  DartType _computeReturnTypeContext(MemberBuilder member) {
    if (member is KernelProcedureBuilder) {
      return member.procedure.function.returnType;
    } else {
      assert(member is KernelConstructorBuilder);
      return const DynamicType();
    }
  }

  @override
  void finishFunction(List<Expression> annotations, FormalParameters formals,
      AsyncMarker asyncModifier, Statement body) {
    debugEvent("finishFunction");
    typePromoter.finished();

    KernelFunctionBuilder builder = member;
    if (formals?.parameters != null) {
      for (int i = 0; i < formals.parameters.length; i++) {
        KernelFormalParameterBuilder parameter = formals.parameters[i];
        if (parameter.isOptional) {
          VariableDeclaration realParameter = builder.formals[i].target;
          Expression initializer =
              parameter.target.initializer ?? forest.literalNull(
                  // TODO(ahe): Should store: realParameter.fileOffset
                  // https://github.com/dart-lang/sdk/issues/32289
                  null);
          realParameter.initializer = initializer..parent = realParameter;
          _typeInferrer.inferParameterInitializer(
              this, initializer, realParameter.type);
        }
      }
    }

    _typeInferrer.inferFunctionBody(
        this, _computeReturnTypeContext(member), asyncModifier, body);

    // For async, async*, and sync* functions with declared return types, we need
    // to determine whether those types are valid.
    // TODO(hillerstrom): currently, we need to check whether [strongMode] is
    // enabled for two reasons:
    // 1) the [isSubtypeOf] predicate produces false-negatives when [strongMode]
    // is false.
    // 2) the member [typeEnvironment] might be null when [strongMode] is false.
    // This particular behaviour can be observed when running the fasta perf
    // benchmarks.
    bool strongMode = library.loader.target.strongMode;
    if (strongMode && builder.returnType != null) {
      DartType returnType = builder.function.returnType;
      // We use the same trick in each case below. For example to decide whether
      // Future<T> <: [returnType] for every T, we rely on Future<Bot> and
      // transitivity of the subtyping relation because Future<Bot> <: Future<T>
      // for every T.

      // We use [problem == null] to signal success.
      Message problem;
      switch (asyncModifier) {
        case AsyncMarker.Async:
          DartType futureBottomType = library.loader.futureOfBottom;
          if (!typeEnvironment.isSubtypeOf(futureBottomType, returnType)) {
            problem = fasta.messageIllegalAsyncReturnType;
          }
          break;

        case AsyncMarker.AsyncStar:
          DartType streamBottomType = library.loader.streamOfBottom;
          if (returnType is VoidType) {
            problem = fasta.messageIllegalAsyncGeneratorVoidReturnType;
          } else if (!typeEnvironment.isSubtypeOf(
              streamBottomType, returnType)) {
            problem = fasta.messageIllegalAsyncGeneratorReturnType;
          }
          break;

        case AsyncMarker.SyncStar:
          DartType iterableBottomType = library.loader.iterableOfBottom;
          if (returnType is VoidType) {
            problem = fasta.messageIllegalSyncGeneratorVoidReturnType;
          } else if (!typeEnvironment.isSubtypeOf(
              iterableBottomType, returnType)) {
            problem = fasta.messageIllegalSyncGeneratorReturnType;
          }
          break;

        case AsyncMarker.Sync:
          break; // skip
        case AsyncMarker.SyncYielding:
          unexpected("async, async*, sync, or sync*", "$asyncModifier",
              member.charOffset, uri);
          break;
      }

      if (problem != null) {
        // TODO(hillerstrom): once types get annotated with location
        // information, we can improve the quality of the error message by
        // using the offset of [returnType] (and the length of its name).
        addProblem(problem, member.charOffset, member.name.length);
      }
    }

    if (builder.kind == ProcedureKind.Setter) {
      if (formals?.parameters == null ||
          formals.parameters.length != 1 ||
          formals.parameters.single.isOptional) {
        int charOffset = formals?.charOffset ??
            body?.fileOffset ??
            builder.target.fileOffset;
        if (body == null) {
          body = new EmptyStatement()..fileOffset = charOffset;
        }
        if (builder.formals != null) {
          // Illegal parameters were removed by the function builder.
          // Add them as local variable to put them in scope of the body.
          List<Statement> statements = <Statement>[];
          for (KernelFormalParameterBuilder parameter in builder.formals) {
            statements.add(parameter.target);
          }
          statements.add(body);
          body = forest.block(null, statements, null)..fileOffset = charOffset;
        }
        body = wrapInProblemStatement(
            body, fasta.messageSetterWithWrongNumberOfFormals);
      }
    }
    // No-such-method forwarders get their bodies injected during outline
    // building, so we should skip them here.
    bool isNoSuchMethodForwarder = (builder.function.parent is Procedure &&
        (builder.function.parent as Procedure).isNoSuchMethodForwarder);
    if (!builder.isExternal && !isNoSuchMethodForwarder) {
      builder.body = body;
    } else {
      if (body != null) {
        builder.body =
            wrapInProblemStatement(body, fasta.messageExternalMethodWithBody);
      }
    }
    Member target = builder.target;
    _typeInferrer.inferMetadata(this, annotations);
    for (Expression annotation in annotations ?? const []) {
      target.addAnnotation(annotation);
    }
    if (builder is KernelConstructorBuilder) {
      finishConstructor(builder, asyncModifier);
    } else if (builder is KernelProcedureBuilder) {
      builder.asyncModifier = asyncModifier;
    } else {
      unhandled("${builder.runtimeType}", "finishFunction", builder.charOffset,
          builder.fileUri);
    }

    resolveRedirectingFactoryTargets();
  }

  void resolveRedirectingFactoryTargets() {
    for (StaticInvocation invocation in redirectingFactoryInvocations) {
      // If the invocation was invalid, it has already been desugared into
      // an exception throwing expression. There is nothing to resolve anymore.
      if (invocation.parent == null) {
        continue;
      }

      Procedure initialTarget = invocation.target;
      Expression replacementNode;

      RedirectionTarget redirectionTarget = getRedirectionTarget(initialTarget,
          strongMode: library.loader.target.strongMode);
      Member resolvedTarget = redirectionTarget?.target;

      if (resolvedTarget == null) {
        String name = constructorNameForDiagnostics(initialTarget.name.name,
            className: initialTarget.enclosingClass.name);
        // TODO(dmitryas): Report this error earlier.
        replacementNode = buildProblem(
                fasta.templateCyclicRedirectingFactoryConstructors
                    .withArguments(name),
                initialTarget.fileOffset,
                name.length)
            .desugared;
      } else if (resolvedTarget is Constructor &&
          resolvedTarget.enclosingClass.isAbstract) {
        replacementNode = evaluateArgumentsBefore(
            forest.arguments(invocation.arguments.positional, null,
                types: invocation.arguments.types,
                named: invocation.arguments.named),
            buildAbstractClassInstantiationError(
                fasta.templateAbstractRedirectedClassInstantiation
                    .withArguments(resolvedTarget.enclosingClass.name),
                resolvedTarget.enclosingClass.name,
                initialTarget.fileOffset));
      } else {
        RedirectingFactoryBody redirectingFactoryBody =
            getRedirectingFactoryBody(resolvedTarget);
        if (redirectingFactoryBody != null) {
          // If the redirection target is itself a redirecting factory, it means
          // that it is unresolved.
          assert(redirectingFactoryBody.isUnresolved);
          String errorName = redirectingFactoryBody.unresolvedName;

          replacementNode = new SyntheticExpressionJudgment(
              throwNoSuchMethodError(
                  forest.literalNull(null)..fileOffset = invocation.fileOffset,
                  errorName,
                  forest.arguments(invocation.arguments.positional, null,
                      types: invocation.arguments.types,
                      named: invocation.arguments.named),
                  initialTarget.fileOffset));
        } else {
          Substitution substitution = Substitution.fromPairs(
              initialTarget.function.typeParameters,
              invocation.arguments.types);
          invocation.arguments.types.clear();
          invocation.arguments.types.length =
              redirectionTarget.typeArguments.length;
          for (int i = 0; i < invocation.arguments.types.length; i++) {
            invocation.arguments.types[i] =
                substitution.substituteType(redirectionTarget.typeArguments[i]);
          }

          replacementNode = buildStaticInvocation(
              resolvedTarget,
              forest.arguments(invocation.arguments.positional, null,
                  types: invocation.arguments.types,
                  named: invocation.arguments.named),
              constness: invocation.isConst
                  ? Constness.explicitConst
                  : Constness.explicitNew,
              charOffset: invocation.fileOffset);
          // TODO(dmitryas): Find a better way to unwrap
          // [SyntheticExpressionJudgment] or not to build it in the first place
          // when it's not needed.
          if (replacementNode is SyntheticExpressionJudgment) {
            replacementNode =
                (replacementNode as SyntheticExpressionJudgment).desugared;
          }
        }
      }

      invocation.replaceWith(replacementNode);
    }
    redirectingFactoryInvocations.clear();
  }

  @override
  List<Expression> finishMetadata(TreeNode parent) {
    List<Expression> expressions = pop();
    _typeInferrer.inferMetadata(this, expressions);

    // The invocation of [resolveRedirectingFactoryTargets] below may change the
    // root nodes of the annotation expressions.  We need to have a parent of
    // the annotation nodes before the resolution is performed, to collect and
    // return them later.  If [parent] is not provided, [temporaryParent] is
    // used.
    ListLiteral temporaryParent;

    if (parent is Class) {
      for (Expression expression in expressions) {
        parent.addAnnotation(expression);
      }
    } else if (parent is Library) {
      for (Expression expression in expressions) {
        parent.addAnnotation(expression);
      }
    } else if (parent is LibraryDependency) {
      for (Expression expression in expressions) {
        parent.addAnnotation(expression);
      }
    } else if (parent is LibraryPart) {
      for (Expression expression in expressions) {
        parent.addAnnotation(expression);
      }
    } else if (parent is Member) {
      for (Expression expression in expressions) {
        parent.addAnnotation(expression);
      }
    } else if (parent is Typedef) {
      for (Expression expression in expressions) {
        parent.addAnnotation(expression);
      }
    } else if (parent is TypeParameter) {
      for (Expression expression in expressions) {
        parent.addAnnotation(expression);
      }
    } else if (parent is VariableDeclaration) {
      for (Expression expression in expressions) {
        parent.addAnnotation(expression);
      }
    } else {
      temporaryParent = new ListLiteral(expressions);
    }
    resolveRedirectingFactoryTargets();
    return temporaryParent != null ? temporaryParent.expressions : expressions;
  }

  @override
  Expression parseSingleExpression(
      Parser parser, Token token, FunctionNode parameters) {
    List<KernelTypeVariableBuilder> typeParameterBuilders;
    for (TypeParameter typeParameter in parameters.typeParameters) {
      typeParameterBuilders ??= <KernelTypeVariableBuilder>[];
      typeParameterBuilders.add(
          new KernelTypeVariableBuilder.fromKernel(typeParameter, library));
    }
    enterFunctionTypeScope(typeParameterBuilders);

    List<KernelFormalParameterBuilder> formals =
        parameters.positionalParameters.length == 0
            ? null
            : new List<KernelFormalParameterBuilder>(
                parameters.positionalParameters.length);
    for (int i = 0; i < parameters.positionalParameters.length; i++) {
      VariableDeclaration formal = parameters.positionalParameters[i];
      formals[i] = new KernelFormalParameterBuilder(
          null, 0, null, formal.name, false, library, formal.fileOffset)
        ..declaration = formal;
    }
    enterLocalScope(
        null,
        new FormalParameters(formals, offsetForToken(token), noLength, uri)
            .computeFormalParameterScope(scope, member, this));

    token = parser.parseExpression(parser.syntheticPreviousToken(token));

    Expression expression = popForValue();
    Token eof = token.next;

    if (!eof.isEof) {
      expression = wrapInLocatedProblem(
          expression,
          fasta.messageExpectedOneExpression
              .withLocation(uri, eof.charOffset, eof.length));
    }

    ReturnJudgment fakeReturn = new ReturnJudgment(null, expression);

    _typeInferrer.inferFunctionBody(
        this, const DynamicType(), AsyncMarker.Sync, fakeReturn);

    return fakeReturn.expression;
  }

  Expression parseFieldInitializer(Token token) {
    Parser parser = new Parser(this);
    token = parser.parseExpression(parser.syntheticPreviousToken(token));
    Expression expression = popForValue();
    checkEmpty(token.charOffset);
    return expression;
  }

  void finishConstructor(
      KernelConstructorBuilder builder, AsyncMarker asyncModifier) {
    /// Quotes below are from [Dart Programming Language Specification, 4th
    /// Edition](
    /// https://ecma-international.org/publications/files/ECMA-ST/ECMA-408.pdf).
    assert(builder == member);
    Constructor constructor = builder.constructor;
    if (asyncModifier != AsyncMarker.Sync) {
      // TODO(ahe): Change this to a null check.
      int offset = builder.body?.fileOffset ?? builder.charOffset;
      constructor.initializers.add(buildInvalidInitializer(
          buildProblem(fasta.messageConstructorNotSync, offset, noLength),
          offset));
    }
    if (needsImplicitSuperInitializer) {
      /// >If no superinitializer is provided, an implicit superinitializer
      /// >of the form super() is added at the end of k’s initializer list,
      /// >unless the enclosing class is class Object.
      Constructor superTarget = lookupConstructor(emptyName, isSuper: true);
      Initializer initializer;
      Arguments arguments = forest.argumentsEmpty(noLocation);
      if (superTarget == null ||
          checkArgumentsForFunction(superTarget.function, arguments,
                  builder.charOffset, const <TypeParameter>[]) !=
              null) {
        String superclass = classBuilder.supertype.fullNameForErrors;
        int length = constructor.name.name.length;
        if (length == 0) {
          length = (constructor.parent as Class).name.length;
        }
        initializer = buildInvalidInitializer(
            buildProblem(
                    fasta.templateSuperclassHasNoDefaultConstructor
                        .withArguments(superclass),
                    builder.charOffset,
                    length)
                .desugared,
            builder.charOffset);
      } else {
        initializer = buildSuperInitializer(
            true, superTarget, arguments, builder.charOffset);
      }
      constructor.initializers.add(initializer);
    }
    setParents(constructor.initializers, constructor);
    if (constructor.function.body == null) {
      /// >If a generative constructor c is not a redirecting constructor
      /// >and no body is provided, then c implicitly has an empty body {}.
      /// We use an empty statement instead.
      constructor.function.body = new EmptyStatement();
      constructor.function.body.parent = constructor.function;
    }
  }

  @override
  void endExpressionStatement(Token token) {
    debugEvent("ExpressionStatement");
    push(forest.expressionStatement(popForEffect(), token));
  }

  @override
  void endArguments(int count, Token beginToken, Token endToken) {
    debugEvent("Arguments");
    List<Object> arguments = count == 0
        ? <Object>[]
        : const FixedNullableList<Object>().pop(stack, count);
    if (arguments == null) {
      push(new ParserRecovery(beginToken.charOffset));
      return;
    }
    int firstNamedArgumentIndex = arguments.length;
    for (int i = 0; i < arguments.length; i++) {
      Object node = arguments[i];
      if (node is NamedExpression) {
        firstNamedArgumentIndex =
            i < firstNamedArgumentIndex ? i : firstNamedArgumentIndex;
      } else {
        Expression argument = toValue(node);
        arguments[i] = argument;
        if (i > firstNamedArgumentIndex) {
          arguments[i] = new NamedExpression(
              "#$i",
              buildProblem(fasta.messageExpectedNamedArgument,
                  forest.readOffset(argument), noLength))
            ..fileOffset = beginToken.charOffset;
        }
      }
    }
    if (firstNamedArgumentIndex < arguments.length) {
      List<Expression> positional = new List<Expression>.from(
          arguments.getRange(0, firstNamedArgumentIndex));
      List<NamedExpression> named = new List<NamedExpression>.from(
          arguments.getRange(firstNamedArgumentIndex, arguments.length));
      push(forest.arguments(positional, beginToken, named: named));
    } else {
      // TODO(kmillikin): Find a way to avoid allocating a second list in the
      // case where there were no named arguments, which is a common one.
      push(forest.arguments(new List<Expression>.from(arguments), beginToken));
    }
  }

  @override
  void handleParenthesizedCondition(Token token) {
    debugEvent("ParenthesizedCondition");
    push(forest.parenthesizedCondition(token, popForValue(), token.endGroup));
  }

  @override
  void handleParenthesizedExpression(Token token) {
    debugEvent("ParenthesizedExpression");
    Expression value = popForValue();
    if (value is ShadowLargeIntLiteral) {
      // We need to know that the expression was parenthesized because we will
      // treat -n differently from -(n).  If the expression occurs in a double
      // context, -n is a double literal and -(n) is an application of unary- to
      // an integer literal.  And in any other context, '-' is part of the
      // syntax of -n, i.e., -9223372036854775808 is OK and it is the minimum
      // 64-bit integer, and '-' is an application of unary- in -(n), i.e.,
      // -(9223372036854775808) is an error because the literal does not fit in
      // 64-bits.
      push(value..isParenthesized = true);
    } else {
      push(new ParenthesizedExpressionGenerator(this, token.endGroup, value));
    }
  }

  @override
  void handleSend(Token beginToken, Token endToken) {
    debugEvent("Send");
    Arguments arguments = pop();
    List<UnresolvedType<KernelTypeBuilder>> typeArguments = pop();
    Object receiver = pop();
    if (arguments != null && typeArguments != null) {
      assert(forest.argumentsTypeArguments(arguments).isEmpty);
      forest.argumentsSetTypeArguments(
          arguments, buildDartTypeArguments(typeArguments));
    } else {
      assert(typeArguments == null);
    }
    if (receiver is Identifier) {
      Name name = new Name(receiver.name, library.library);
      if (arguments == null) {
        push(new IncompletePropertyAccessGenerator(this, beginToken, name));
      } else {
        push(new SendAccessGenerator(
            this, beginToken, name, forest.castArguments(arguments)));
      }
    } else if (arguments == null) {
      push(receiver);
    } else {
      push(finishSend(receiver, arguments, beginToken.charOffset));
    }
  }

  @override
  finishSend(Object receiver, Arguments arguments, int charOffset) {
    if (receiver is Generator) {
      return receiver.doInvocation(charOffset, arguments);
    } else if (receiver is ParserRecovery) {
      return new ParserErrorGenerator(this, null, fasta.messageSyntheticToken);
    } else {
      return buildMethodInvocation(
          toValue(receiver), callName, arguments, charOffset,
          isImplicitCall: true);
    }
  }

  @override
  void beginCascade(Token token) {
    debugEvent("beginCascade");
    Expression expression = popForValue();
    if (expression is CascadeJudgment) {
      push(expression);
      push(new VariableUseGenerator(this, token, expression.variable));
      expression.extend();
    } else {
      VariableDeclaration variable = new VariableDeclarationJudgment.forValue(
          expression, functionNestingLevel)
        ..fileOffset = expression.fileOffset;
      push(new CascadeJudgment(variable)..fileOffset = expression.fileOffset);
      push(new VariableUseGenerator(this, token, variable));
    }
  }

  @override
  void endCascade() {
    debugEvent("endCascade");
    Expression expression = popForEffect();
    CascadeJudgment cascadeReceiver = pop();
    cascadeReceiver.finalize(expression);
    push(cascadeReceiver);
  }

  @override
  void beginCaseExpression(Token caseKeyword) {
    debugEvent("beginCaseExpression");
    super.push(constantContext);
    constantContext = ConstantContext.inferred;
  }

  @override
  void endCaseExpression(Token colon) {
    debugEvent("endCaseExpression");
    Expression expression = popForValue();
    constantContext = pop();
    super.push(expression);
  }

  @override
  void beginBinaryExpression(Token token) {
    if (optional("&&", token) || optional("||", token)) {
      Expression lhs = popForValue();
      typePromoter.enterLogicalExpression(lhs, token.stringValue);
      push(lhs);
    }
  }

  @override
  void endBinaryExpression(Token token) {
    debugEvent("BinaryExpression");
    if (optional(".", token) || optional("..", token)) {
      return doDotOrCascadeExpression(token);
    }
    if (optional("&&", token) || optional("||", token)) {
      return doLogicalExpression(token);
    }
    if (optional("??", token)) return doIfNull(token);
    if (optional("?.", token)) return doIfNotNull(token);
    Expression argument = popForValue();
    Object receiver = pop();
    bool isSuper = false;
    if (receiver is ThisAccessGenerator && receiver.isSuper) {
      ThisAccessGenerator thisAccessorReceiver = receiver;
      isSuper = true;
      receiver = forest.thisExpression(thisAccessorReceiver.token);
    }
    push(buildBinaryOperator(toValue(receiver), token, argument, isSuper));
  }

  Expression buildBinaryOperator(
      Expression a, Token token, Expression b, bool isSuper) {
    bool negate = false;
    String operator = token.stringValue;
    if (identical("!=", operator)) {
      operator = "==";
      negate = true;
    }
    if (!isBinaryOperator(operator) && !isMinusOperator(operator)) {
      return buildProblem(fasta.templateInvalidOperator.withArguments(token),
          token.charOffset, token.length);
    } else {
      Expression result = buildMethodInvocation(a, new Name(operator),
          forest.arguments(<Expression>[b], noLocation), token.charOffset,
          // This *could* be a constant expression, we can't know without
          // evaluating [a] and [b].
          isConstantExpression: !isSuper,
          isSuper: isSuper);
      return negate ? forest.notExpression(result, null, true) : result;
    }
  }

  void doLogicalExpression(Token token) {
    Expression argument = popForValue();
    Expression receiver = pop();
    Expression logicalExpression =
        forest.logicalExpression(receiver, token, argument);
    typePromoter.exitLogicalExpression(argument, logicalExpression);
    push(logicalExpression);
  }

  /// Handle `a ?? b`.
  void doIfNull(Token token) {
    Expression b = popForValue();
    Expression a = popForValue();
    VariableDeclaration variable = new VariableDeclaration.forValue(a);
    push(new IfNullJudgment(
        variable,
        forest.conditionalExpression(
            buildIsNull(new VariableGet(variable), offsetForToken(token), this),
            token,
            b,
            null,
            new VariableGet(variable)))
      ..fileOffset = offsetForToken(token));
  }

  /// Handle `a?.b(...)`.
  void doIfNotNull(Token token) {
    Object send = pop();
    if (send is IncompleteSendGenerator) {
      push(send.withReceiver(pop(), token.charOffset, isNullAware: true));
    } else {
      pop();
      token = token.next;
      push(buildProblem(fasta.templateExpectedIdentifier.withArguments(token),
          offsetForToken(token), lengthForToken(token)));
    }
  }

  void doDotOrCascadeExpression(Token token) {
    Object send = pop();
    if (send is IncompleteSendGenerator) {
      Object receiver = optional(".", token) ? pop() : popForValue();
      push(send.withReceiver(receiver, token.charOffset));
    } else {
      pop();
      token = token.next;
      push(buildProblem(fasta.templateExpectedIdentifier.withArguments(token),
          offsetForToken(token), lengthForToken(token)));
    }
  }

  bool areArgumentsCompatible(FunctionNode function, Arguments arguments) {
    // TODO(ahe): Implement this.
    return true;
  }

  @override
  Expression throwNoSuchMethodError(
      Expression receiver, String name, Arguments arguments, int charOffset,
      {Member candidate,
      bool isSuper: false,
      bool isGetter: false,
      bool isSetter: false,
      bool isStatic: false,
      LocatedMessage message}) {
    int length = name.length;
    int periodIndex = name.lastIndexOf(".");
    if (periodIndex != -1) {
      length -= periodIndex + 1;
    }
    Name kernelName = new Name(name, library.library);
    List<LocatedMessage> context;
    if (candidate != null) {
      Uri uri = candidate.location.file;
      int offset = candidate.fileOffset;
      Message contextMessage;
      int length = noLength;
      if (offset == -1 && candidate is Constructor) {
        offset = candidate.enclosingClass.fileOffset;
        contextMessage = fasta.templateCandidateFoundIsDefaultConstructor
            .withArguments(candidate.enclosingClass.name);
      } else {
        length = name.length;
        contextMessage = fasta.messageCandidateFound;
      }
      context = [contextMessage.withLocation(uri, offset, length)];
    }
    if (message == null) {
      if (isGetter) {
        message = warnUnresolvedGet(kernelName, charOffset,
                isSuper: isSuper, reportWarning: false, context: context)
            .withLocation(uri, charOffset, length);
      } else if (isSetter) {
        message = warnUnresolvedSet(kernelName, charOffset,
                isSuper: isSuper, reportWarning: false, context: context)
            .withLocation(uri, charOffset, length);
      } else {
        message = warnUnresolvedMethod(kernelName, charOffset,
                isSuper: isSuper, reportWarning: false, context: context)
            .withLocation(uri, charOffset, length);
      }
    }
    if (!library.loader.target.strongMode &&
        constantContext == ConstantContext.none) {
      addProblem(message.messageObject, message.charOffset, message.length,
          wasHandled: true, context: context);
      return new SyntheticExpressionJudgment(
          forest.throwExpression(
              null,
              library.loader.instantiateNoSuchMethodError(
                  receiver, name, forest.castArguments(arguments), charOffset,
                  isMethod: !isGetter && !isSetter,
                  isGetter: isGetter,
                  isSetter: isSetter,
                  isStatic: isStatic,
                  isTopLevel: !isStatic && !isSuper))
            ..fileOffset = charOffset)
        ..fileOffset = charOffset;
    }
    return buildProblem(
            message.messageObject, message.charOffset, message.length,
            context: context)
        .desugared;
  }

  @override
  Message warnUnresolvedGet(Name name, int charOffset,
      {bool isSuper: false,
      bool reportWarning: true,
      List<LocatedMessage> context}) {
    Message message = isSuper
        ? fasta.templateSuperclassHasNoGetter.withArguments(name.name)
        : fasta.templateGetterNotFound.withArguments(name.name);
    if (reportWarning) {
      addProblemErrorIfConst(message, charOffset, name.name.length,
          context: context);
    }
    return message;
  }

  @override
  Message warnUnresolvedSet(Name name, int charOffset,
      {bool isSuper: false,
      bool reportWarning: true,
      List<LocatedMessage> context}) {
    Message message = isSuper
        ? fasta.templateSuperclassHasNoSetter.withArguments(name.name)
        : fasta.templateSetterNotFound.withArguments(name.name);
    if (reportWarning) {
      addProblemErrorIfConst(message, charOffset, name.name.length,
          context: context);
    }
    return message;
  }

  @override
  Message warnUnresolvedMethod(Name name, int charOffset,
      {bool isSuper: false,
      bool reportWarning: true,
      List<LocatedMessage> context}) {
    String plainName = name.name;
    int dotIndex = plainName.lastIndexOf(".");
    if (dotIndex != -1) {
      plainName = plainName.substring(dotIndex + 1);
    }
    // TODO(ahe): This is rather brittle. We would probably be better off with
    // more precise location information in this case.
    int length = plainName.length;
    if (plainName.startsWith("[")) {
      length = 1;
    }
    Message message = isSuper
        ? fasta.templateSuperclassHasNoMethod.withArguments(name.name)
        : fasta.templateMethodNotFound.withArguments(name.name);
    if (reportWarning) {
      addProblemErrorIfConst(message, charOffset, length, context: context);
    }
    return message;
  }

  @override
  void warnTypeArgumentsMismatch(String name, int expected, int charOffset) {
    addProblemErrorIfConst(
        fasta.templateTypeArgumentMismatch.withArguments(expected),
        charOffset,
        name.length);
  }

  @override
  Member lookupInstanceMember(Name name,
      {bool isSetter: false, bool isSuper: false}) {
    Class cls = classBuilder.cls;
    if (classBuilder.isPatch) {
      if (isSuper) {
        // The super class is only correctly found through the origin class.
        cls = classBuilder.origin.cls;
      } else {
        Member member =
            hierarchy.getInterfaceMember(cls, name, setter: isSetter);
        if (member?.parent == cls) {
          // Only if the member is found in the patch can we use it.
          return member;
        } else {
          // Otherwise, we need to keep searching in the origin class.
          cls = classBuilder.origin.cls;
        }
      }
    }

    if (isSuper) {
      cls = cls.superclass;
      if (cls == null) return null;
    }
    Member target = isSuper
        ? hierarchy.getDispatchTarget(cls, name, setter: isSetter)
        : hierarchy.getInterfaceMember(cls, name, setter: isSetter);
    if (isSuper && target == null) {
      if (classBuilder.cls.isMixinDeclaration ||
          (library.loader.target.backendTarget.enableSuperMixins &&
              classBuilder.isAbstract)) {
        target = hierarchy.getInterfaceMember(cls, name, setter: isSetter);
      }
    }
    return target;
  }

  @override
  Constructor lookupConstructor(Name name, {bool isSuper}) {
    Class cls = classBuilder.cls;
    if (isSuper) {
      cls = cls.superclass;
      while (cls.isMixinApplication) {
        cls = cls.superclass;
      }
    }
    if (cls != null) {
      for (Constructor constructor in cls.constructors) {
        if (constructor.name == name) return constructor;
      }
    }

    /// Performs a similar lookup to [lookupConstructor], but using a slower
    /// implementation.
    Constructor lookupConstructorWithPatches(Name name, bool isSuper) {
      ClassBuilder<TypeBuilder, Object> builder = classBuilder.origin;

      ClassBuilder<TypeBuilder, Object> getSuperclass(
          ClassBuilder<TypeBuilder, Object> builder) {
        // This way of computing the superclass is slower than using the kernel
        // objects directly.
        Object supertype = builder.supertype;
        if (supertype is NamedTypeBuilder<TypeBuilder, Object>) {
          Object builder = supertype.declaration;
          if (builder is ClassBuilder<TypeBuilder, Object>) return builder;
        }
        return null;
      }

      if (isSuper) {
        builder = getSuperclass(builder)?.origin;
        while (builder?.isMixinApplication ?? false) {
          builder = getSuperclass(builder)?.origin;
        }
      }
      if (builder != null) {
        Class target = builder.target;
        for (Constructor constructor in target.constructors) {
          if (constructor.name == name) return constructor;
        }
      }
      return null;
    }

    return lookupConstructorWithPatches(name, isSuper);
  }

  @override
  void handleIdentifier(Token token, IdentifierContext context) {
    debugEvent("handleIdentifier");
    String name = token.lexeme;
    if (name.startsWith("deprecated") &&
        // Note that the previous check is redundant, but faster in the common
        // case (when [name] isn't deprecated).
        (name == "deprecated" || name.startsWith("deprecated_"))) {
      addProblem(fasta.templateUseOfDeprecatedIdentifier.withArguments(name),
          offsetForToken(token), lengthForToken(token));
    }
    if (context.isScopeReference) {
      assert(!inInitializer ||
          this.scope == enclosingScope ||
          this.scope.parent == enclosingScope);
      // This deals with this kind of initializer: `C(a) : a = a;`
      Scope scope = inInitializer ? enclosingScope : this.scope;
      push(scopeLookup(scope, name, token));
      return;
    } else if (context.inDeclaration) {
      if (context == IdentifierContext.topLevelVariableDeclaration ||
          context == IdentifierContext.fieldDeclaration) {
        constantContext =
            member.isConst ? ConstantContext.inferred : ConstantContext.none;
      }
    } else if (constantContext != ConstantContext.none &&
        !context.allowedInConstantExpression) {
      addProblem(
          fasta.messageNotAConstantExpression, token.charOffset, token.length);
    }
    if (token.isSynthetic) {
      push(new ParserRecovery(offsetForToken(token)));
    } else {
      push(new Identifier.preserveToken(token));
    }
  }

  /// Look up [name] in [scope] using [token] as location information (both to
  /// report problems and as the file offset in the generated kernel code).
  /// [isQualified] should be true if [name] is a qualified access (which
  /// implies that it shouldn't be turned into a [ThisPropertyAccessGenerator]
  /// if the name doesn't resolve in the scope).
  @override
  scopeLookup(Scope scope, String name, Token token,
      {bool isQualified: false, PrefixBuilder prefix}) {
    int charOffset = offsetForToken(token);
    if (token.isSynthetic) {
      return new ParserErrorGenerator(this, token, fasta.messageSyntheticToken);
    }
    Declaration declaration = scope.lookup(name, charOffset, uri);
    if (declaration is UnlinkedDeclaration) {
      return new UnlinkedGenerator(this, token, declaration);
    }
    if (declaration == null &&
        prefix == null &&
        (classBuilder?.isPatch ?? false)) {
      // The scope of a patched method includes the origin class.
      declaration =
          classBuilder.origin.findStaticBuilder(name, charOffset, uri, library);
    }
    if (declaration != null &&
        declaration.isInstanceMember &&
        inFieldInitializer &&
        !inInitializer) {
      return new IncompleteErrorGenerator(this, token, declaration.target,
          fasta.templateThisAccessInFieldInitializer.withArguments(name));
    }
    if (declaration == null ||
        (!isInstanceContext && declaration.isInstanceMember)) {
      Name n = new Name(name, library.library);
      if (!isQualified && isInstanceContext) {
        assert(declaration == null);
        if (constantContext != ConstantContext.none || member.isField) {
          return new UnresolvedNameGenerator(this, token, n);
        }
        return new ThisPropertyAccessGenerator(this, token, n,
            lookupInstanceMember(n), lookupInstanceMember(n, isSetter: true));
      } else if (ignoreMainInGetMainClosure &&
          name == "main" &&
          member?.name == "_getMainClosure") {
        return forest.literalNull(null)..fileOffset = charOffset;
      } else {
        return new UnresolvedNameGenerator(this, token, n);
      }
    } else if (declaration.isTypeDeclaration) {
      return new TypeUseGenerator(this, token, declaration, name);
    } else if (declaration.isLocal) {
      if (constantContext != ConstantContext.none &&
          !declaration.isConst &&
          !member.isConstructor) {
        addProblem(
            fasta.messageNotAConstantExpression, charOffset, token.length);
      }
      // An initializing formal parameter might be final without its
      // VariableDeclaration being final. See
      // [ProcedureBuilder.computeFormalParameterInitializerScope]. If that
      // wasn't the case, we could always use [VariableUseGenerator].
      if (declaration.isFinal) {
        Object fact = typePromoter.getFactForAccess(
            declaration.target, functionNestingLevel);
        Object scope = typePromoter.currentScope;
        return new ReadOnlyAccessGenerator(
            this,
            token,
            new VariableGetJudgment(declaration.target, fact, scope)
              ..fileOffset = charOffset,
            name);
      } else {
        return new VariableUseGenerator(this, token, declaration.target);
      }
    } else if (declaration.isInstanceMember) {
      if (constantContext != ConstantContext.none &&
          !inInitializer &&
          // TODO(ahe): This is a hack because Fasta sets up the scope
          // "this.field" parameters according to old semantics. Under the new
          // semantics, such parameters introduces a new parameter with that
          // name that should be resolved here.
          !member.isConstructor) {
        addProblem(
            fasta.messageNotAConstantExpression, charOffset, token.length);
      }
      Name n = new Name(name, library.library);
      Member getter;
      Member setter;
      if (declaration is AccessErrorBuilder) {
        setter = declaration.parent.target;
        getter = lookupInstanceMember(n);
      } else {
        getter = declaration.target;
        setter = lookupInstanceMember(n, isSetter: true);
      }
      return new ThisPropertyAccessGenerator(this, token, n, getter, setter);
    } else if (declaration.isRegularMethod) {
      assert(declaration.isStatic || declaration.isTopLevel);
      return new StaticAccessGenerator(this, token, declaration.target, null);
    } else if (declaration is PrefixBuilder) {
      assert(prefix == null);
      return new PrefixUseGenerator(this, token, declaration);
    } else if (declaration is LoadLibraryBuilder) {
      return new LoadLibraryGenerator(this, token, declaration);
    } else {
      if (declaration.hasProblem && declaration is! AccessErrorBuilder)
        return declaration;
      Declaration setter;
      if (declaration.isSetter) {
        setter = declaration;
      } else if (declaration.isGetter) {
        setter = scope.lookupSetter(name, charOffset, uri);
      } else if (declaration.isField && !declaration.isFinal) {
        setter = declaration;
      }
      StaticAccessGenerator generator = new StaticAccessGenerator.fromBuilder(
          this, declaration, token, setter);
      if (constantContext != ConstantContext.none) {
        Member readTarget = generator.readTarget;
        if (!(readTarget is Field && readTarget.isConst ||
            // Static tear-offs are also compile time constants.
            readTarget is Procedure)) {
          addProblem(
              fasta.messageNotAConstantExpression, charOffset, token.length);
        }
      }
      return generator;
    }
  }

  @override
  void handleQualified(Token period) {
    debugEvent("Qualified");
    Object node = pop();
    Object qualifier = pop();
    if (qualifier is ParserRecovery) {
      push(qualifier);
    } else if (node is ParserRecovery) {
      push(node);
    } else {
      Identifier identifier = node;
      push(identifier.withQualifier(qualifier));
    }
  }

  @override
  void beginLiteralString(Token token) {
    debugEvent("beginLiteralString");
    push(token);
  }

  @override
  void handleStringPart(Token token) {
    debugEvent("StringPart");
    push(token);
  }

  @override
  void endLiteralString(int interpolationCount, Token endToken) {
    debugEvent("endLiteralString");
    if (interpolationCount == 0) {
      Token token = pop();
      String value = unescapeString(token.lexeme, token, this);
      push(forest.literalString(value, token));
    } else {
      int count = 1 + interpolationCount * 2;
      List<Object> parts = const FixedNullableList<Object>().pop(stack, count);
      if (parts == null) {
        push(new ParserRecovery(endToken.charOffset));
        return;
      }
      Token first = parts.first;
      Token last = parts.last;
      Quote quote = analyzeQuote(first.lexeme);
      List<Expression> expressions = <Expression>[];
      // Contains more than just \' or \".
      if (first.lexeme.length > 1) {
        String value =
            unescapeFirstStringPart(first.lexeme, quote, first, this);
        if (value.isNotEmpty) {
          expressions.add(forest.literalString(value, first));
        }
      }
      for (int i = 1; i < parts.length - 1; i++) {
        Object part = parts[i];
        if (part is Token) {
          if (part.lexeme.length != 0) {
            String value = unescape(part.lexeme, quote, part, this);
            expressions.add(forest.literalString(value, part));
          }
        } else {
          expressions.add(toValue(part));
        }
      }
      // Contains more than just \' or \".
      if (last.lexeme.length > 1) {
        String value = unescapeLastStringPart(last.lexeme, quote, last, this);
        if (value.isNotEmpty) {
          expressions.add(forest.literalString(value, last));
        }
      }
      push(forest.stringConcatenationExpression(expressions, endToken));
    }
  }

  @override
  void handleNativeClause(Token nativeToken, bool hasName) {
    debugEvent("NativeClause");
    if (hasName) {
      forest.asLiteralString(pop());
    }
  }

  @override
  void handleScript(Token token) {
    debugEvent("Script");
  }

  @override
  void handleStringJuxtaposition(int literalCount) {
    debugEvent("StringJuxtaposition");
    List<Expression> parts = popListForValue(literalCount);
    List<Expression> expressions;
    // Flatten string juxtapositions of string interpolation.
    for (int i = 0; i < parts.length; i++) {
      Expression part = parts[i];
      if (part is StringConcatenation) {
        if (expressions == null) {
          expressions = parts.sublist(0, i);
        }
        for (Expression expression in part.expressions) {
          expressions.add(expression);
        }
      } else {
        if (expressions != null) {
          expressions.add(part);
        }
      }
    }
    push(forest.stringConcatenationExpression(expressions ?? parts, null));
  }

  @override
  void handleLiteralInt(Token token) {
    debugEvent("LiteralInt");
    int value = int.tryParse(token.lexeme);
    if (!library.loader.target.strongMode) {
      if (value == null) {
        push(unhandled(
            'large integer', 'handleLiteralInt', token.charOffset, uri));
      } else {
        push(forest.literalInt(value, token));
      }
      return;
    }
    // Postpone parsing of literals resulting in a negative value
    // (hex literals >= 2^63). These are only allowed when not negated.
    if (value == null || value < 0) {
      push(forest.literalLargeInt(token.lexeme, token));
    } else {
      push(forest.literalInt(value, token));
    }
  }

  @override
  void handleEmptyFunctionBody(Token semicolon) {
    debugEvent("ExpressionFunctionBody");
    endBlockFunctionBody(0, null, semicolon);
  }

  @override
  void handleExpressionFunctionBody(Token arrowToken, Token endToken) {
    debugEvent("ExpressionFunctionBody");
    endReturnStatement(true, arrowToken.next, endToken);
  }

  @override
  void endReturnStatement(
      bool hasExpression, Token beginToken, Token endToken) {
    debugEvent("ReturnStatement");
    Expression expression = hasExpression ? popForValue() : null;
    if (expression != null && inConstructor) {
      push(buildProblemStatement(
          fasta.messageConstructorWithReturnType, beginToken.charOffset));
    } else {
      push(forest.returnStatement(beginToken, expression, endToken));
    }
  }

  @override
  void beginThenStatement(Token token) {
    Expression condition = popForValue();
    enterThenForTypePromotion(condition);
    push(condition);
    super.beginThenStatement(token);
  }

  @override
  void endThenStatement(Token token) {
    typePromoter.enterElse();
    super.endThenStatement(token);
  }

  @override
  void endIfStatement(Token ifToken, Token elseToken) {
    Statement elsePart = popStatementIfNotNull(elseToken);
    Statement thenPart = popStatement();
    Expression condition = pop();
    typePromoter.exitConditional();
    push(forest.ifStatement(ifToken, condition, thenPart, elseToken, elsePart));
  }

  @override
  void endVariableInitializer(Token assignmentOperator) {
    debugEvent("VariableInitializer");
    assert(assignmentOperator.stringValue == "=");
    pushNewLocalVariable(popForValue(), equalsToken: assignmentOperator);
  }

  @override
  void handleNoVariableInitializer(Token token) {
    debugEvent("NoVariableInitializer");
    bool isConst = (currentLocalVariableModifiers & constMask) != 0;
    bool isFinal = (currentLocalVariableModifiers & finalMask) != 0;
    Expression initializer;
    if (!optional("in", token)) {
      // A for-in loop-variable can't have an initializer. So let's remain
      // silent if the next token is `in`. Since a for-in loop can only have
      // one variable it must be followed by `in`.
      if (isConst) {
        initializer = buildProblem(
            fasta.templateConstFieldWithoutInitializer
                .withArguments(token.lexeme),
            token.charOffset,
            token.length);
      } else if (isFinal) {
        initializer = buildProblem(
            fasta.templateFinalFieldWithoutInitializer
                .withArguments(token.lexeme),
            token.charOffset,
            token.length);
      }
    }
    pushNewLocalVariable(initializer);
  }

  void pushNewLocalVariable(Expression initializer, {Token equalsToken}) {
    Object node = pop();
    if (node is ParserRecovery) {
      push(node);
      return;
    }
    Identifier identifier = node;
    assert(currentLocalVariableModifiers != -1);
    bool isConst = (currentLocalVariableModifiers & constMask) != 0;
    bool isFinal = (currentLocalVariableModifiers & finalMask) != 0;
    assert(isConst == (constantContext == ConstantContext.inferred));
    VariableDeclaration variable = new VariableDeclarationJudgment(
        identifier.name, functionNestingLevel,
        forSyntheticToken: deprecated_extractToken(identifier).isSynthetic,
        initializer: initializer,
        type: buildDartType(currentLocalVariableType),
        isFinal: isFinal,
        isConst: isConst)
      ..fileOffset = identifier.charOffset
      ..fileEqualsOffset = offsetForToken(equalsToken);
    library.checkBoundsInVariableDeclaration(variable, typeEnvironment);
    push(variable);
  }

  @override
  void beginFieldInitializer(Token token) {
    inFieldInitializer = true;
  }

  @override
  void endFieldInitializer(Token assignmentOperator, Token token) {
    debugEvent("FieldInitializer");
    inFieldInitializer = false;
    assert(assignmentOperator.stringValue == "=");
    push(popForValue());
  }

  @override
  void handleNoFieldInitializer(Token token) {
    debugEvent("NoFieldInitializer");
    if (constantContext != ConstantContext.none) {
      // Creating a null value to prevent the Dart VM from crashing.
      push(forest.literalNull(token));
    } else {
      push(NullValue.FieldInitializer);
    }
  }

  @override
  void endInitializedIdentifier(Token nameToken) {
    // TODO(ahe): Use [InitializedIdentifier] here?
    debugEvent("InitializedIdentifier");
    Object node = pop();
    if (node is ParserRecovery) {
      push(node);
      return;
    }
    VariableDeclaration variable = node;
    variable.fileOffset = nameToken.charOffset;
    push(variable);
    declareVariable(variable, scope);
  }

  @override
  void beginVariablesDeclaration(Token token, Token varFinalOrConst) {
    debugEvent("beginVariablesDeclaration");
    UnresolvedType<KernelTypeBuilder> type = pop();
    int modifiers = Modifier.validateVarFinalOrConst(varFinalOrConst?.lexeme);
    super.push(currentLocalVariableModifiers);
    super.push(currentLocalVariableType ?? NullValue.Type);
    currentLocalVariableType = type;
    currentLocalVariableModifiers = modifiers;
    super.push(constantContext);
    constantContext = ((modifiers & constMask) != 0)
        ? ConstantContext.inferred
        : ConstantContext.none;
  }

  @override
  void endVariablesDeclaration(int count, Token endToken) {
    debugEvent("VariablesDeclaration");
    if (count == 1) {
      Object node = pop();
      constantContext = pop();
      currentLocalVariableType = pop();
      currentLocalVariableModifiers = pop();
      List<Expression> annotations = pop();
      if (node is ParserRecovery) {
        push(node);
        return;
      }
      VariableDeclaration variable = node;
      if (annotations != null) {
        for (Expression annotation in annotations) {
          variable.addAnnotation(annotation);
        }
      }
      push(variable);
    } else {
      List<VariableDeclaration> variables =
          const FixedNullableList<VariableDeclaration>().pop(stack, count);
      constantContext = pop();
      currentLocalVariableType = pop();
      currentLocalVariableModifiers = pop();
      List<Expression> annotations = pop();
      if (variables == null) {
        push(new ParserRecovery(offsetForToken(endToken)));
        return;
      }
      if (annotations != null) {
        bool isFirstVariable = true;
        for (VariableDeclarationJudgment variable in variables) {
          for (Expression annotation in annotations) {
            variable.addAnnotation(annotation);
          }
          if (isFirstVariable) {
            isFirstVariable = false;
          } else {
            variable.infersAnnotations = false;
          }
        }
      }
      push(forest.variablesDeclaration(variables, uri));
    }
  }

  @override
  void endBlock(int count, Token openBrace, Token closeBrace) {
    debugEvent("Block");
    Statement block = popBlock(count, openBrace, closeBrace);
    exitLocalScope();
    push(block);
  }

  void handleInvalidTopLevelBlock(Token token) {
    // TODO(danrubel): Consider improved recovery by adding this block
    // as part of a synthetic top level function.
    pop(); // block
  }

  @override
  void handleAssignmentExpression(Token token) {
    debugEvent("AssignmentExpression");
    Expression value = popForValue();
    Object generator = pop();
    if (generator is! Generator) {
      push(buildProblem(fasta.messageNotAnLvalue, offsetForToken(token),
          lengthForToken(token)));
    } else {
      push(new DelayedAssignment(
          this, token, generator, value, token.stringValue));
    }
  }

  @override
  void enterLoop(int charOffset) {
    if (peek() is LabelTarget) {
      LabelTarget target = peek();
      enterBreakTarget(charOffset, target.breakTarget);
      enterContinueTarget(charOffset, target.continueTarget);
    } else {
      enterBreakTarget(charOffset);
      enterContinueTarget(charOffset);
    }
  }

  void exitLoopOrSwitch(Statement statement) {
    if (problemInLoopOrSwitch != null) {
      push(problemInLoopOrSwitch);
      problemInLoopOrSwitch = null;
    } else {
      push(statement);
    }
  }

  List<VariableDeclaration> buildForInitVariableDeclarations(
      variableOrExpression) {
    if (variableOrExpression is VariableDeclaration) {
      return <VariableDeclaration>[variableOrExpression];
    } else if (forest.isVariablesDeclaration(variableOrExpression)) {
      return forest
          .variablesDeclarationExtractDeclarations(variableOrExpression);
    } else if (variableOrExpression is List<Object>) {
      List<VariableDeclaration> variables = <VariableDeclaration>[];
      for (Object v in variableOrExpression) {
        variables.addAll(buildForInitVariableDeclarations(v));
      }
      return variables;
    } else if (variableOrExpression == null) {
      return <VariableDeclaration>[];
    }
    return null;
  }

  List<Expression> buildForInitExpressions(variableOrExpression) {
    if (variableOrExpression is Expression) {
      return <Expression>[variableOrExpression];
    } else if (variableOrExpression is ExpressionStatementJudgment) {
      return <Expression>[variableOrExpression.expression];
    }
    return null;
  }

  @override
  void endForStatement(Token forKeyword, Token leftParen, Token leftSeparator,
      int updateExpressionCount, Token endToken) {
    debugEvent("ForStatement");
    Statement body = popStatement();
    List<Expression> updates = popListForEffect(updateExpressionCount);
    Statement conditionStatement = popStatement();
    Object variableOrExpression = pop();

    variableOrExpression = variableOrExpression is Generator
        ? variableOrExpression.buildForEffect()
        : variableOrExpression;
    List<Expression> initializers =
        buildForInitExpressions(variableOrExpression);
    List<VariableDeclaration> variableList = initializers == null
        ? buildForInitVariableDeclarations(variableOrExpression)
        : null;

    exitLocalScope();
    JumpTarget continueTarget = exitContinueTarget();
    JumpTarget breakTarget = exitBreakTarget();
    if (continueTarget.hasUsers) {
      body = forest.syntheticLabeledStatement(body);
      continueTarget.resolveContinues(forest, body);
    }
    Expression condition;
    if (forest.isExpressionStatement(conditionStatement)) {
      condition =
          forest.getExpressionFromExpressionStatement(conditionStatement);
    } else {
      assert(forest.isEmptyStatement(conditionStatement));
    }
    Statement result = forest.forStatement(
        forKeyword,
        leftParen,
        variableList,
        initializers,
        leftSeparator,
        condition,
        conditionStatement,
        updates,
        leftParen.endGroup,
        body);
    if (breakTarget.hasUsers) {
      result = forest.syntheticLabeledStatement(result);
      breakTarget.resolveBreaks(forest, result);
    }
    if (variableOrExpression is ParserRecovery) {
      problemInLoopOrSwitch ??= buildProblemStatement(
          fasta.messageSyntheticToken, variableOrExpression.charOffset,
          suppressMessage: true);
    }
    exitLoopOrSwitch(result);
  }

  @override
  void endAwaitExpression(Token keyword, Token endToken) {
    debugEvent("AwaitExpression");
    push(forest.awaitExpression(popForValue(), keyword));
  }

  @override
  void handleAsyncModifier(Token asyncToken, Token starToken) {
    debugEvent("AsyncModifier");
    push(asyncMarkerFromTokens(asyncToken, starToken));
  }

  @override
  void handleLiteralList(
      int count, Token leftBracket, Token constKeyword, Token rightBracket) {
    debugEvent("LiteralList");
    List<Expression> expressions = popListForValue(count);
    List<UnresolvedType<KernelTypeBuilder>> typeArguments = pop();
    DartType typeArgument;
    if (typeArguments != null) {
      if (typeArguments.length > 1) {
        addProblem(
            fasta.messageListLiteralTooManyTypeArguments,
            offsetForToken(leftBracket),
            lengthOfSpan(leftBracket, leftBracket.endGroup));
      } else {
        typeArgument = buildDartType(typeArguments.single);
        if (library.loader.target.strongMode) {
          typeArgument =
              instantiateToBounds(typeArgument, coreTypes.objectClass);
        }
      }
    }
    Expression node = forest.literalList(
        constKeyword,
        constKeyword != null || constantContext == ConstantContext.inferred,
        typeArgument,
        typeArguments,
        leftBracket,
        expressions,
        rightBracket);
    library.checkBoundsInListLiteral(node, typeEnvironment);
    push(node);
  }

  @override
  void handleLiteralBool(Token token) {
    debugEvent("LiteralBool");
    bool value = optional("true", token);
    assert(value || optional("false", token));
    push(forest.literalBool(value, token));
  }

  @override
  void handleLiteralDouble(Token token) {
    debugEvent("LiteralDouble");
    push(forest.literalDouble(double.parse(token.lexeme), token));
  }

  @override
  void handleLiteralNull(Token token) {
    debugEvent("LiteralNull");
    push(forest.literalNull(token));
  }

  @override
  void handleLiteralMap(
      int count, Token leftBrace, Token constKeyword, Token rightBrace) {
    debugEvent("LiteralMap");
    List<MapEntry> entries =
        const GrowableList<MapEntry>().pop(stack, count) ?? <MapEntry>[];
    List<UnresolvedType<KernelTypeBuilder>> typeArguments = pop();
    DartType keyType;
    DartType valueType;
    if (typeArguments != null) {
      if (typeArguments.length != 2) {
        addProblem(
            fasta.messageMapLiteralTypeArgumentMismatch,
            offsetForToken(leftBrace),
            lengthOfSpan(leftBrace, leftBrace.endGroup));
      } else {
        keyType = buildDartType(typeArguments[0]);
        valueType = buildDartType(typeArguments[1]);
        if (library.loader.target.strongMode) {
          keyType = instantiateToBounds(keyType, coreTypes.objectClass);
          valueType = instantiateToBounds(valueType, coreTypes.objectClass);
        }
      }
    }
    Expression node = forest.literalMap(
        constKeyword,
        constKeyword != null || constantContext == ConstantContext.inferred,
        keyType,
        valueType,
        typeArguments,
        leftBrace,
        entries,
        rightBrace);
    library.checkBoundsInMapLiteral(node, typeEnvironment);
    push(node);
  }

  @override
  void endLiteralMapEntry(Token colon, Token endToken) {
    debugEvent("LiteralMapEntry");
    Expression value = popForValue();
    Expression key = popForValue();
    push(forest.mapEntry(key, colon, value));
  }

  String symbolPartToString(name) {
    if (name is Identifier) {
      return name.name;
    } else if (name is Operator) {
      return name.name;
    } else {
      return unhandled("${name.runtimeType}", "symbolPartToString", -1, uri);
    }
  }

  @override
  void endLiteralSymbol(Token hashToken, int identifierCount) {
    debugEvent("LiteralSymbol");
    if (identifierCount == 1) {
      Object part = pop();
      if (part is ParserRecovery) {
        push(new ParserErrorGenerator(
            this, hashToken, fasta.messageSyntheticToken));
      } else {
        push(forest.literalSymbolSingluar(
            symbolPartToString(part), hashToken, part));
      }
    } else {
      List<Identifier> parts =
          const FixedNullableList<Identifier>().pop(stack, identifierCount);
      if (parts == null) {
        push(new ParserErrorGenerator(
            this, hashToken, fasta.messageSyntheticToken));
        return;
      }
      String value = symbolPartToString(parts.first);
      for (int i = 1; i < parts.length; i++) {
        value += ".${symbolPartToString(parts[i])}";
      }
      push(forest.literalSymbolMultiple(value, hashToken, parts));
    }
  }

  @override
  void handleType(Token beginToken) {
    // TODO(ahe): The scope is wrong for return types of generic functions.
    debugEvent("Type");
    List<UnresolvedType<KernelTypeBuilder>> arguments = pop();
    Object name = pop();
    if (name is QualifiedName) {
      QualifiedName qualified = name;
      Object prefix = qualified.qualifier;
      Token suffix = deprecated_extractToken(qualified);
      if (prefix is Generator) {
        name = prefix.qualifiedLookup(suffix);
      } else {
        String name = getNodeName(prefix);
        String displayName = debugName(name, suffix.lexeme);
        int offset = offsetForToken(beginToken);
        push(new UnresolvedType<KernelTypeBuilder>(
            new KernelNamedTypeBuilder(name, null)
              ..bind(new KernelInvalidTypeBuilder(
                  name,
                  fasta.templateNotAType
                      .withArguments(displayName)
                      .withLocation(
                          uri, offset, lengthOfSpan(beginToken, suffix)))),
            offset,
            uri));
        return;
      }
    }
    KernelTypeBuilder result;
    if (name is Generator) {
      result = name.buildTypeWithResolvedArguments(arguments);
      if (result == null) {
        unhandled("null", "result", beginToken.charOffset, uri);
      }
    } else if (name is TypeBuilder) {
      result = name.build(library);
      if (result == null) {
        unhandled("null", "result", beginToken.charOffset, uri);
      }
    } else if (name is ProblemBuilder) {
      // TODO(ahe): Arguments could be passed here.
      result = new KernelNamedTypeBuilder(name.name, null)
        ..bind(new KernelInvalidTypeBuilder(
            name.name,
            name.message.withLocation(
                name.fileUri, name.charOffset, name.name.length)));
    } else {
      unhandled(
          "${name.runtimeType}", "handleType", beginToken.charOffset, uri);
    }
    push(new UnresolvedType<KernelTypeBuilder>(
        result, beginToken.charOffset, uri));
  }

  @override
  void beginFunctionType(Token beginToken) {
    debugEvent("beginFunctionType");
  }

  void enterFunctionTypeScope(List<KernelTypeVariableBuilder> typeVariables) {
    debugEvent("enterFunctionTypeScope");
    enterLocalScope(null,
        scope.createNestedScope("function-type scope", isModifiable: true));
    if (typeVariables != null) {
      ScopeBuilder scopeBuilder = new ScopeBuilder(scope);
      for (KernelTypeVariableBuilder builder in typeVariables) {
        String name = builder.name;
        KernelTypeVariableBuilder existing = scopeBuilder[name];
        if (existing == null) {
          scopeBuilder.addMember(name, builder);
        } else {
          reportDuplicatedDeclaration(existing, name, builder.charOffset);
        }
      }
    }
  }

  @override
  void endFunctionType(Token functionToken) {
    debugEvent("FunctionType");
    FormalParameters formals = pop();
    UnresolvedType<KernelTypeBuilder> returnType = pop();
    List<KernelTypeVariableBuilder> typeVariables = pop();
    UnresolvedType<KernelTypeBuilder> type =
        formals.toFunctionType(returnType, typeVariables);
    exitLocalScope();
    push(type);
  }

  @override
  void handleVoidKeyword(Token token) {
    debugEvent("VoidKeyword");
    int offset = offsetForToken(token);
    push(new UnresolvedType<KernelTypeBuilder>(
        new KernelNamedTypeBuilder("void", null)
          ..bind(new VoidTypeBuilder<KernelTypeBuilder, VoidType>(
              const VoidType(), library, offset)),
        offset,
        uri));
  }

  @override
  void handleAsOperator(Token operator) {
    debugEvent("AsOperator");
    DartType type = buildDartType(pop());
    library.checkBoundsInType(type, typeEnvironment, operator.charOffset);
    Expression expression = popForValue();
    if (constantContext != ConstantContext.none) {
      push(buildProblem(
              fasta.templateNotConstantExpression
                  .withArguments('As expression'),
              operator.charOffset,
              operator.length)
          .desugared);
    } else {
      Expression node = forest.asExpression(expression, type, operator);
      push(node);
    }
  }

  @override
  void handleIsOperator(Token isOperator, Token not) {
    debugEvent("IsOperator");
    DartType type = buildDartType(pop());
    Expression operand = popForValue();
    bool isInverted = not != null;
    Expression isExpression =
        forest.isExpression(operand, isOperator, not, type);
    library.checkBoundsInType(type, typeEnvironment, isOperator.charOffset);
    if (operand is VariableGet) {
      typePromoter.handleIsCheck(isExpression, isInverted, operand.variable,
          type, functionNestingLevel);
    }
    if (constantContext != ConstantContext.none) {
      push(buildProblem(
              fasta.templateNotConstantExpression
                  .withArguments('Is expression'),
              isOperator.charOffset,
              isOperator.length)
          .desugared);
    } else {
      push(isExpression);
    }
  }

  @override
  void beginConditionalExpression(Token question) {
    Expression condition = popForValue();
    typePromoter.enterThen(condition);
    push(condition);
    super.beginConditionalExpression(question);
  }

  @override
  void handleConditionalExpressionColon() {
    Expression then = popForValue();
    typePromoter.enterElse();
    push(then);
    super.handleConditionalExpressionColon();
  }

  @override
  void endConditionalExpression(Token question, Token colon) {
    debugEvent("ConditionalExpression");
    Expression elseExpression = popForValue();
    Expression thenExpression = pop();
    Expression condition = pop();
    typePromoter.exitConditional();
    push(forest.conditionalExpression(
        condition, question, thenExpression, colon, elseExpression));
  }

  @override
  void handleThrowExpression(Token throwToken, Token endToken) {
    debugEvent("ThrowExpression");
    Expression expression = popForValue();
    if (constantContext != ConstantContext.none) {
      push(buildProblem(
          fasta.templateNotConstantExpression.withArguments('Throw'),
          throwToken.offset,
          throwToken.length));
    } else {
      push(forest.throwExpression(throwToken, expression));
    }
  }

  @override
  void beginFormalParameter(Token token, MemberKind kind, Token covariantToken,
      Token varFinalOrConst) {
    push((covariantToken != null ? covariantMask : 0) |
        Modifier.validateVarFinalOrConst(varFinalOrConst?.lexeme));
  }

  @override
  void endFormalParameter(Token thisKeyword, Token periodAfterThis,
      Token nameToken, FormalParameterKind kind, MemberKind memberKind) {
    debugEvent("FormalParameter");
    if (thisKeyword != null) {
      if (!inConstructor) {
        handleRecoverableError(fasta.messageFieldInitializerOutsideConstructor,
            thisKeyword, thisKeyword);
        thisKeyword = null;
      }
    }
    Object nameNode = pop();
    UnresolvedType<KernelTypeBuilder> type = pop();
    if (functionNestingLevel == 0) {
      // TODO(ahe): The type we compute here may be different from what is
      // computed in the outline phase. We should make sure that the outline
      // phase computes the same type. See
      // pkg/front_end/testcases/deferred_type_annotation.dart for an example
      // where not calling [buildDartType] leads to a missing compile-time
      // error. Also, notice that the type of the problematic parameter isn't
      // `invalid-type`.
      buildDartType(type);
    }
    int modifiers = pop();
    if (inCatchClause) {
      modifiers |= finalMask;
    }
    List<Expression> annotations = pop();
    if (nameNode is ParserRecovery) {
      push(nameNode);
      return;
    }
    Identifier name = nameNode;
    KernelFormalParameterBuilder parameter;
    if (!inCatchClause &&
        functionNestingLevel == 0 &&
        memberKind != MemberKind.GeneralizedFunctionType) {
      ProcedureBuilder<TypeBuilder> member = this.member;
      parameter = member.getFormal(name.name);
      if (parameter == null) {
        push(new ParserRecovery(nameToken.charOffset));
        return;
      }
    } else {
      parameter = new KernelFormalParameterBuilder(null, modifiers,
          type?.builder, name?.name, false, library, offsetForToken(nameToken));
    }
    VariableDeclaration variable =
        parameter.build(library, functionNestingLevel);
    Expression initializer = name?.initializer;
    if (initializer != null) {
      if (member is KernelRedirectingFactoryBuilder) {
        KernelRedirectingFactoryBuilder factory = member;
        addProblem(
            fasta.templateDefaultValueInRedirectingFactoryConstructor
                .withArguments(factory.redirectionTarget.fullNameForErrors),
            initializer.fileOffset,
            noLength);
      } else {
        variable.initializer = initializer..parent = variable;
      }
    }
    if (annotations != null) {
      if (functionNestingLevel == 0) {
        _typeInferrer.inferMetadata(this, annotations);
      }
      for (Expression annotation in annotations) {
        variable.addAnnotation(annotation);
      }
    }
    push(parameter);
  }

  @override
  void endOptionalFormalParameters(
      int count, Token beginToken, Token endToken) {
    debugEvent("OptionalFormalParameters");
    FormalParameterKind kind = optional("{", beginToken)
        ? FormalParameterKind.optionalNamed
        : FormalParameterKind.optionalPositional;
    // When recovering from an empty list of optional arguments, count may be
    // 0. It might be simpler if the parser didn't call this method in that
    // case, however, then [beginOptionalFormalParameters] wouldn't always be
    // matched by this method.
    List<KernelFormalParameterBuilder> parameters =
        const FixedNullableList<KernelFormalParameterBuilder>()
            .pop(stack, count);
    if (parameters == null) {
      push(new ParserRecovery(offsetForToken(beginToken)));
    } else {
      for (KernelFormalParameterBuilder parameter in parameters) {
        parameter.kind = kind;
      }
      push(parameters);
    }
  }

  @override
  void beginFunctionTypedFormalParameter(Token token) {
    debugEvent("beginFunctionTypedFormalParameter");
    functionNestingLevel++;
  }

  @override
  void endFunctionTypedFormalParameter(Token nameToken) {
    debugEvent("FunctionTypedFormalParameter");
    if (inCatchClause || functionNestingLevel != 0) {
      exitLocalScope();
    }
    FormalParameters formals = pop();
    UnresolvedType<KernelTypeBuilder> returnType = pop();
    List<KernelTypeVariableBuilder> typeVariables = pop();
    UnresolvedType<KernelTypeBuilder> type =
        formals.toFunctionType(returnType, typeVariables);
    exitLocalScope();
    push(type);
    functionNestingLevel--;
  }

  @override
  void beginFormalParameterDefaultValueExpression() {
    super.push(constantContext);
    constantContext = ConstantContext.none;
  }

  @override
  void endFormalParameterDefaultValueExpression() {
    debugEvent("FormalParameterDefaultValueExpression");
    Object defaultValueExpression = pop();
    constantContext = pop();
    push(defaultValueExpression);
  }

  @override
  void handleValuedFormalParameter(Token equals, Token token) {
    debugEvent("ValuedFormalParameter");
    Expression initializer = popForValue();
    Identifier name = pop();
    push(new InitializedIdentifier(name, initializer));
  }

  @override
  void handleFormalParameterWithoutValue(Token token) {
    debugEvent("FormalParameterWithoutValue");
  }

  @override
  void beginFormalParameters(Token token, MemberKind kind) {
    super.push(constantContext);
    constantContext = ConstantContext.none;
  }

  @override
  void endFormalParameters(
      int count, Token beginToken, Token endToken, MemberKind kind) {
    debugEvent("FormalParameters");
    List<KernelFormalParameterBuilder> optionals;
    int optionalsCount = 0;
    if (count > 0 && peek() is List<KernelFormalParameterBuilder>) {
      optionals = pop();
      count--;
      optionalsCount = optionals.length;
    }
    List<KernelFormalParameterBuilder> parameters =
        const FixedNullableList<KernelFormalParameterBuilder>()
            .popPadded(stack, count, optionalsCount);
    if (optionals != null && parameters != null) {
      parameters.setRange(count, count + optionalsCount, optionals);
    }
    assert(parameters?.isNotEmpty ?? true);
    FormalParameters formals = new FormalParameters(parameters,
        offsetForToken(beginToken), lengthOfSpan(beginToken, endToken), uri);
    constantContext = pop();
    push(formals);
    if ((inCatchClause || functionNestingLevel != 0) &&
        kind != MemberKind.GeneralizedFunctionType) {
      enterLocalScope(
          null,
          formals.computeFormalParameterScope(
              scope, member ?? classBuilder ?? library, this));
    }
  }

  @override
  void beginCatchClause(Token token) {
    debugEvent("beginCatchClause");
    inCatchClause = true;
  }

  @override
  void endCatchClause(Token token) {
    debugEvent("CatchClause");
    inCatchClause = false;
    push(inCatchBlock);
    inCatchBlock = true;
  }

  @override
  void handleCatchBlock(Token onKeyword, Token catchKeyword, Token comma) {
    debugEvent("CatchBlock");
    Statement body = pop();
    inCatchBlock = pop();
    if (catchKeyword != null) {
      exitLocalScope();
    }
    FormalParameters catchParameters = popIfNotNull(catchKeyword);
    DartType exceptionType =
        buildDartType(popIfNotNull(onKeyword)) ?? const DynamicType();
    KernelFormalParameterBuilder exception;
    KernelFormalParameterBuilder stackTrace;
    List<Statement> compileTimeErrors;
    if (catchParameters?.parameters != null) {
      int parameterCount = catchParameters.parameters.length;
      if (parameterCount > 0) {
        exception = catchParameters.parameters[0];
        exception.build(library, functionNestingLevel).type = exceptionType;
        if (parameterCount > 1) {
          stackTrace = catchParameters.parameters[1];
          stackTrace.build(library, functionNestingLevel).type =
              coreTypes.stackTraceClass.rawType;
        }
      }
      if (parameterCount > 2) {
        // If parameterCount is 0, the parser reported an error already.
        if (parameterCount != 0) {
          for (int i = 2; i < parameterCount; i++) {
            KernelFormalParameterBuilder parameter =
                catchParameters.parameters[i];
            compileTimeErrors ??= <Statement>[];
            compileTimeErrors.add(buildProblemStatement(
                fasta.messageCatchSyntaxExtraParameters, parameter.charOffset,
                length: parameter.name.length));
          }
        }
      }
    }
    push(forest.catchClause(
        onKeyword,
        exceptionType,
        catchKeyword,
        exception?.target,
        stackTrace?.target,
        coreTypes.stackTraceClass.rawType,
        body));
    if (compileTimeErrors == null) {
      push(NullValue.Block);
    } else {
      push(forest.block(null, compileTimeErrors, null));
    }
  }

  @override
  void endTryStatement(int catchCount, Token tryKeyword, Token finallyKeyword) {
    Statement finallyBlock = popStatementIfNotNull(finallyKeyword);
    List<Catch> catchBlocks;
    List<Statement> compileTimeErrors;
    if (catchCount != 0) {
      List<Object> catchBlocksAndErrors =
          const FixedNullableList<Object>().pop(stack, catchCount * 2);
      catchBlocks = new List<Catch>.filled(catchCount, null, growable: true);
      for (int i = 0; i < catchCount; i++) {
        catchBlocks[i] = catchBlocksAndErrors[i * 2];
        Statement error = catchBlocksAndErrors[i * 2 + 1];
        if (error != null) {
          compileTimeErrors ??= <Statement>[];
          compileTimeErrors.add(error);
        }
      }
    }
    Statement tryBlock = popStatement();
    Statement tryStatement = forest.tryStatement(
        tryKeyword, tryBlock, catchBlocks, finallyKeyword, finallyBlock);
    if (compileTimeErrors != null) {
      compileTimeErrors.add(tryStatement);
      push(forest.block(null, compileTimeErrors, null));
    } else {
      push(tryStatement);
    }
  }

  @override
  void handleNoExpression(Token token) {
    debugEvent("NoExpression");
    push(NullValue.Expression);
  }

  @override
  void handleIndexedExpression(
      Token openSquareBracket, Token closeSquareBracket) {
    debugEvent("IndexedExpression");
    Expression index = popForValue();
    Object receiver = pop();
    if (receiver is ThisAccessGenerator && receiver.isSuper) {
      push(new SuperIndexedAccessGenerator(
          this,
          openSquareBracket,
          index,
          lookupInstanceMember(indexGetName, isSuper: true),
          lookupInstanceMember(indexSetName, isSuper: true)));
    } else {
      push(IndexedAccessGenerator.make(
          this, openSquareBracket, toValue(receiver), index, null, null));
    }
  }

  @override
  void handleUnaryPrefixExpression(Token token) {
    debugEvent("UnaryPrefixExpression");
    Object receiver = pop();
    if (optional("!", token)) {
      push(forest.notExpression(toValue(receiver), token, false));
    } else {
      String operator = token.stringValue;
      Expression receiverValue;
      if (optional("-", token)) {
        operator = "unary-";
      }
      bool isSuper = false;
      if (receiver is ThisAccessGenerator && receiver.isSuper) {
        isSuper = true;
        receiverValue = forest.thisExpression(receiver.token);
      } else {
        receiverValue = toValue(receiver);
      }
      push(buildMethodInvocation(receiverValue, new Name(operator),
          forest.argumentsEmpty(noLocation), token.charOffset,
          // This *could* be a constant expression, we can't know without
          // evaluating [receiver].
          isConstantExpression: !isSuper,
          isSuper: isSuper));
    }
  }

  Name incrementOperator(Token token) {
    if (optional("++", token)) return plusName;
    if (optional("--", token)) return minusName;
    return unhandled(token.lexeme, "incrementOperator", token.charOffset, u