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.

// @dart = 2.9

library fasta.body_builder;

import 'package:_fe_analyzer_shared/src/flow_analysis/flow_analysis.dart';

import 'package:_fe_analyzer_shared/src/messages/severity.dart' show Severity;

import 'package:_fe_analyzer_shared/src/parser/parser.dart'
    show
        Assert,
        BlockKind,
        FormalParameterKind,
        IdentifierContext,
        MemberKind,
        Parser,
        lengthForToken,
        lengthOfSpan,
        optional;

import 'package:_fe_analyzer_shared/src/parser/quote.dart'
    show
        Quote,
        analyzeQuote,
        unescape,
        unescapeFirstStringPart,
        unescapeLastStringPart,
        unescapeString;

import 'package:_fe_analyzer_shared/src/parser/value_kind.dart';

import 'package:_fe_analyzer_shared/src/scanner/scanner.dart' show Token;

import 'package:_fe_analyzer_shared/src/scanner/token_impl.dart'
    show isBinaryOperator, isMinusOperator, isUserDefinableOperator;

import 'package:_fe_analyzer_shared/src/util/link.dart';

import 'package:kernel/ast.dart';
import 'package:kernel/type_environment.dart';

import '../builder/builder.dart';
import '../builder/class_builder.dart';
import '../builder/constructor_builder.dart';
import '../builder/declaration_builder.dart';
import '../builder/enum_builder.dart';
import '../builder/extension_builder.dart';
import '../builder/field_builder.dart';
import '../builder/formal_parameter_builder.dart';
import '../builder/function_builder.dart';
import '../builder/function_type_builder.dart';
import '../builder/invalid_type_declaration_builder.dart';
import '../builder/library_builder.dart';
import '../builder/member_builder.dart';
import '../builder/modifier_builder.dart';
import '../builder/named_type_builder.dart';
import '../builder/nullability_builder.dart';
import '../builder/prefix_builder.dart';
import '../builder/procedure_builder.dart';
import '../builder/type_alias_builder.dart';
import '../builder/type_builder.dart';
import '../builder/type_declaration_builder.dart';
import '../builder/type_variable_builder.dart';
import '../builder/unresolved_type.dart';
import '../builder/variable_builder.dart';
import '../builder/void_type_declaration_builder.dart';

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

import '../dill/dill_library_builder.dart' show DillLibraryBuilder;

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

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

import '../identifiers.dart'
    show Identifier, InitializedIdentifier, QualifiedName, flattenName;

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

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

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

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

import '../scope.dart';

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

import '../source/source_library_builder.dart' show SourceLibraryBuilder;

import '../source/stack_listener_impl.dart' show offsetForToken;

import '../source/value_kinds.dart';

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

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

import '../type_inference/type_schema.dart' show UnknownType;

import '../util/helpers.dart' show DelayedActionPerformer;

import 'collections.dart';

import 'constness.dart' show Constness;

import 'expression_generator.dart';

import 'expression_generator_helper.dart' show ExpressionGeneratorHelper;

import 'forest.dart' show Forest;

import 'implicit_type_argument.dart' show ImplicitTypeArgument;

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

import 'type_algorithms.dart' show calculateBounds;

import 'kernel_api.dart';

import 'kernel_ast_api.dart';

import 'internal_ast.dart';

import 'kernel_builder.dart';

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

// TODO(danrubel): Remove this once control flow and spread collection support
// has been enabled by default.
const Object invalidCollectionElement = const Object();

class BodyBuilder extends ScopeListener<JumpTarget>
    implements ExpressionGeneratorHelper, EnsureLoaded, DelayedActionPerformer {
  final Forest forest;

  // TODO(ahe): Rename [library] to 'part'.
  @override
  final SourceLibraryBuilder libraryBuilder;

  final ModifierBuilder member;

  /// The class, mixin or extension declaration in which [member] is declared,
  /// if any.
  final DeclarationBuilder declarationBuilder;

  /// The class or mixin declaration in which [member] is declared, if any.
  final ClassBuilder classBuilder;

  final ClassHierarchy hierarchy;

  @override
  final CoreTypes coreTypes;

  final bool isDeclarationInstanceMember;

  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;

  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;

  /// Set to `true` when we are parsing a field initializer either directly
  /// or within an initializer list.
  ///
  /// For instance in `<init>` in
  ///
  ///    var foo = <init>;
  ///    class Class {
  ///      var bar = <init>;
  ///      Class() : <init>;
  ///    }
  ///
  /// This is used to determine whether instance properties are available.
  bool inFieldInitializer = false;

  /// `true` if we are directly in a field initializer of a late field.
  ///
  /// For instance in `<init>` in
  ///
  ///    late var foo = <init>;
  ///    class Class {
  ///      late var bar = <init>;
  ///      Class() : bar = 42;
  ///    }
  ///
  bool inLateFieldInitializer = false;

  /// `true` if we are directly in the initializer of a late local.
  ///
  /// For instance in `<init>` in
  ///
  ///    method() {
  ///      late var foo = <init>;
  ///    }
  ///    class Class {
  ///      method() {
  ///        late var bar = <init>;
  ///      }
  ///    }
  ///
  bool get inLateLocalInitializer => _localInitializerState.head;

  Link<bool> _isOrAsOperatorTypeState = const Link<bool>().prepend(false);

  @override
  bool get inIsOrAsOperatorType => _isOrAsOperatorTypeState.head;

  Link<bool> _localInitializerState = const Link<bool>().prepend(false);

  List<Initializer> _initializers;

  bool inCatchClause = false;

  bool inCatchBlock = false;

  int functionNestingLevel = 0;

  // Set when a spread element is encountered in a collection so the collection
  // needs to be desugared after type inference.
  bool transformCollections = false;

  // Set by type inference when a set literal is encountered that needs to be
  // transformed because the backend target does not support set literals.
  bool transformSetLiterals = false;

  Statement problemInLoopOrSwitch;

  Scope switchScope;

  CloneVisitorNotMembers cloner;

  ConstantContext constantContext = ConstantContext.none;

  UnresolvedType 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>[];

  /// List of redirecting factory invocations delayed for resolution.
  ///
  /// A resolution of a redirecting factory invocation can be delayed because
  /// the inference in the declaration of the redirecting factory isn't done
  /// yet.
  final List<Expression> delayedRedirectingFactoryInvocations = <Expression>[];

  /// List of built type aliased generative constructor invocations that
  /// require unaliasing.
  final List<TypeAliasedConstructorInvocationJudgment>
      typeAliasedConstructorInvocations = [];

  /// List of built type aliased factory constructor invocations that require
  /// unaliasing.
  final List<TypeAliasedFactoryInvocationJudgment>
      typeAliasedFactoryInvocations = [];

  /// Variables with metadata.  Their types need to be inferred late, for
  /// example, in [finishFunction].
  List<VariableDeclaration> variablesWithMetadata;

  /// More than one variable declared in a single statement that has metadata.
  /// Their types need to be inferred late, for example, in [finishFunction].
  List<List<VariableDeclaration>> multiVariablesWithMetadata;

  /// If the current member is an instance member in an extension declaration,
  /// [extensionThis] holds the synthetically add parameter holding the value
  /// for `this`.
  final VariableDeclaration extensionThis;

  final List<TypeParameter> extensionTypeParameters;

  BodyBuilder(
      {this.libraryBuilder,
      this.member,
      this.enclosingScope,
      this.formalParameterScope,
      this.hierarchy,
      this.coreTypes,
      this.declarationBuilder,
      this.isDeclarationInstanceMember,
      this.extensionThis,
      this.extensionTypeParameters,
      this.uri,
      this.typeInferrer})
      : forest = const Forest(),
        classBuilder =
            declarationBuilder is ClassBuilder ? declarationBuilder : null,
        enableNative = libraryBuilder.loader.target.backendTarget
            .enableNative(libraryBuilder.importUri),
        stringExpectedAfterNative = libraryBuilder
            .loader.target.backendTarget.nativeExtensionExpectsString,
        ignoreMainInGetMainClosure =
            libraryBuilder.importUri.scheme == 'dart' &&
                (libraryBuilder.importUri.path == "_builtin" ||
                    libraryBuilder.importUri.path == "ui"),
        needsImplicitSuperInitializer = declarationBuilder is ClassBuilder &&
            coreTypes?.objectClass != declarationBuilder.cls,
        typePromoter = typeInferrer?.typePromoter,
        super(enclosingScope) {
    formalParameterScope?.forEach((String name, Builder builder) {
      if (builder is VariableBuilder) {
        typeInferrer?.assignedVariables?.declare(builder.variable);
      }
    });
  }

  BodyBuilder.withParents(FieldBuilder field, SourceLibraryBuilder part,
      DeclarationBuilder declarationBuilder, TypeInferrer typeInferrer)
      : this(
            libraryBuilder: part,
            member: field,
            enclosingScope: declarationBuilder?.scope ?? field.library.scope,
            formalParameterScope: null,
            hierarchy: part.loader.hierarchy,
            coreTypes: part.loader.coreTypes,
            declarationBuilder: declarationBuilder,
            isDeclarationInstanceMember: field.isDeclarationInstanceMember,
            extensionThis: null,
            uri: field.fileUri,
            typeInferrer: typeInferrer);

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

  BodyBuilder.forOutlineExpression(
      SourceLibraryBuilder library,
      DeclarationBuilder declarationBuilder,
      ModifierBuilder member,
      Scope scope,
      Uri fileUri)
      : this(
            libraryBuilder: library,
            member: member,
            enclosingScope: scope,
            formalParameterScope: null,
            hierarchy: library.loader.hierarchy,
            coreTypes: library.loader.coreTypes,
            declarationBuilder: declarationBuilder,
            isDeclarationInstanceMember:
                member?.isDeclarationInstanceMember ?? false,
            extensionThis: null,
            uri: fileUri,
            typeInferrer: library.loader.typeInferenceEngine
                ?.createLocalTypeInferrer(
                    fileUri, declarationBuilder?.thisType, library, null));

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

  bool get isDeclarationInstanceContext {
    return isDeclarationInstanceMember || member is ConstructorBuilder;
  }

  TypeEnvironment get typeEnvironment => typeInferrer?.typeSchemaEnvironment;

  DartType get implicitTypeArgument => const ImplicitTypeArgument();

  @override
  bool get enableExtensionTypesInLibrary {
    return libraryBuilder.enableExtensionTypesInLibrary;
  }

  @override
  bool get enableConstFunctionsInLibrary {
    return libraryBuilder.enableConstFunctionsInLibrary;
  }

  void _enterLocalState({bool inLateLocalInitializer: false}) {
    _localInitializerState =
        _localInitializerState.prepend(inLateLocalInitializer);
  }

  void _exitLocalState() {
    _localInitializerState = _localInitializerState.tail;
  }

  @override
  void registerVariableAssignment(VariableDeclaration variable) {
    typePromoter?.mutateVariable(variable, functionNestingLevel);
    typeInferrer?.assignedVariables?.write(variable);
  }

  @override
  VariableDeclaration createVariableDeclarationForValue(Expression expression) {
    VariableDeclaration variable =
        forest.createVariableDeclarationForValue(expression);
    typeInferrer?.assignedVariables?.declare(variable);
    return variable;
  }

  @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.createBlock(
        offsetForToken(openBrace),
        offsetForToken(closeBrace),
        const GrowableList<Statement>().pop(stack, count) ?? <Statement>[]);
  }

  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, JumpTarget declaration) {
        if (outerSwitchScope == null) {
          for (Statement statement in declaration.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;
    Builder existing = scope.lookupLocalMember(name, setter: false);
    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 VariableBuilderImpl(
            variable, member ?? classBuilder ?? libraryBuilder, 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);
  }

  void inferAnnotations(TreeNode parent, List<Expression> annotations) {
    if (annotations != null) {
      typeInferrer?.inferMetadata(this, parent, annotations);
      libraryBuilder.loader.transformListPostInference(annotations,
          transformSetLiterals, transformCollections, libraryBuilder.library);
    }
  }

  @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,
          inMetadata: true);
      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, identifier.token,
            new Name(identifier.name, libraryBuilder.nameOrigin));
      }
      if (name?.isNotEmpty ?? false) {
        Token period = periodBeforeName ?? beginToken.next.next;
        Generator generator = expression;
        expression = generator.buildPropertyAccess(
            new IncompletePropertyAccessGenerator(
                this, period.next, new Name(name, libraryBuilder.nameOrigin)),
            period.next.offset,
            false);
      }

      ConstantContext savedConstantContext = pop();
      if (expression is! StaticAccessGenerator &&
          expression is! VariableUseGenerator &&
          // TODO(johnniwinther): Stop using the type of the generator here.
          // Ask a property instead.
          (expression is! ReadOnlyAccessGenerator ||
              expression is TypeUseGenerator ||
              expression is ParenthesizedExpressionGenerator)) {
        Expression value = toValue(expression);
        push(wrapInProblem(value, fasta.messageExpressionNotMetadata,
            value.fileOffset, 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 externalToken,
      Token staticToken,
      Token covariantToken,
      Token lateToken,
      Token varFinalOrConst,
      int count,
      Token beginToken,
      Token endToken) {
    debugEvent("TopLevelFields");
    if (!libraryBuilder.isNonNullableByDefault) {
      reportNonNullableModifierError(lateToken);
      if (externalToken != null) {
        handleRecoverableError(
            fasta.messageExternalField, externalToken, externalToken);
      }
    }
    push(count);
  }

  @override
  void endClassFields(
      Token abstractToken,
      Token externalToken,
      Token staticToken,
      Token covariantToken,
      Token lateToken,
      Token varFinalOrConst,
      int count,
      Token beginToken,
      Token endToken) {
    debugEvent("Fields");
    if (!libraryBuilder.isNonNullableByDefault) {
      reportNonNullableModifierError(lateToken);
      if (abstractToken != null) {
        handleRecoverableError(
            fasta.messageAbstractClassMember, abstractToken, abstractToken);
      }
      if (externalToken != null) {
        handleRecoverableError(
            fasta.messageExternalField, externalToken, externalToken);
      }
    }
    push(count);
  }

  @override
  void finishFields() {
    debugEvent("finishFields");
    int count = pop();
    List<FieldBuilder> fields = <FieldBuilder>[];
    for (int i = 0; i < count; i++) {
      Expression initializer = pop();
      Identifier identifier = pop();
      String name = identifier.name;
      Builder declaration;
      if (declarationBuilder != null) {
        declaration =
            declarationBuilder.lookupLocalMember(name, required: true);
      } else {
        declaration = libraryBuilder.lookupLocalMember(name, required: true);
      }
      FieldBuilder fieldBuilder;
      if (declaration.isField && declaration.next == null) {
        fieldBuilder = declaration;
      } else {
        continue;
      }
      fields.add(fieldBuilder);
      if (initializer != null) {
        if (fieldBuilder.isDuplicate) {
          // 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 if (fieldBuilder.hasBodyBeenBuilt) {
          // The initializer was already compiled (e.g., if it appear in the
          // outline, like constant field initializers) so we do not need to
          // perform type inference or transformations.
        } else {
          initializer = typeInferrer?.inferFieldInitializer(
              this, fieldBuilder.builtType, initializer);

          if (transformCollections || transformSetLiterals) {
            // Wrap the initializer in a temporary parent expression; the
            // transformations need a parent relation.
            Not wrapper = new Not(initializer);
            libraryBuilder.loader.transformPostInference(
                wrapper,
                transformSetLiterals,
                transformCollections,
                libraryBuilder.library);
            initializer = wrapper.operand;
          }
          fieldBuilder.buildBody(coreTypes, initializer);
        }
      } else if (!fieldBuilder.hasBodyBeenBuilt) {
        fieldBuilder.buildBody(coreTypes, null);
      }
    }
    {
      // 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.
    }
    pop(); // Annotations.

    resolveRedirectingFactoryTargets();
    finishVariableMetadata();
  }

  @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() {
    FunctionBuilder member = this.member;
    scope = member.computeFormalParameterInitializerScope(scope);
    if (member is ConstructorBuilder) {
      member.prepareInitializers();
      if (member.formals != null) {
        for (FormalParameterBuilder formal in member.formals) {
          if (formal.isInitializingFormal) {
            List<Initializer> initializers;
            if (member.isExternal) {
              initializers = <Initializer>[
                buildInvalidInitializer(
                    buildProblem(
                        fasta.messageExternalConstructorWithFieldInitializers,
                        formal.charOffset,
                        formal.name.length),
                    formal.charOffset)
              ];
            } else {
              initializers = buildFieldInitializer(
                  formal.name,
                  formal.charOffset,
                  formal.charOffset,
                  new VariableGet(formal.variable),
                  formal: formal);
            }
            for (Initializer initializer in initializers) {
              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);
    Object node = pop();
    List<Initializer> initializers;

    final ModifierBuilder member = this.member;
    if (!(member is ConstructorBuilder && !member.isExternal)) {
      // An error has been reported by the parser.
      initializers = <Initializer>[];
    } else if (node is Initializer) {
      initializers = <Initializer>[node];
    } else if (node is Generator) {
      initializers = node.buildFieldInitializer(initializedFields);
    } else if (node is ConstructorInvocation) {
      initializers = <Initializer>[
        buildSuperInitializer(
            false, node.target, node.arguments, token.charOffset)
      ];
    } else {
      Expression value = toValue(node);
      if (!forest.isThrow(node)) {
        value = wrapInProblem(value, fasta.messageExpectedAnInitializer,
            value.fileOffset, noLength);
      }
      initializers = <Initializer>[
        buildInvalidInitializer(node, token.charOffset)
      ];
    }
    _initializers ??= <Initializer>[];
    _initializers.addAll(initializers);
  }

  DartType _computeReturnTypeContext(MemberBuilder member) {
    if (member is ProcedureBuilder) {
      return member.actualProcedure.function.returnType;
    } else {
      assert(member is ConstructorBuilder);
      return const DynamicType();
    }
  }

  @override
  void finishFunction(
      FormalParameters formals, AsyncMarker asyncModifier, Statement body) {
    debugEvent("finishFunction");
    typePromoter?.finished();
    typeInferrer?.assignedVariables?.finish();

    FunctionBuilder builder = member;
    if (extensionThis != null) {
      typeInferrer?.flowAnalysis?.declare(extensionThis, true);
    }
    if (formals?.parameters != null) {
      for (int i = 0; i < formals.parameters.length; i++) {
        FormalParameterBuilder parameter = formals.parameters[i];
        typeInferrer?.flowAnalysis?.declare(parameter.variable, true);
      }
      for (int i = 0; i < formals.parameters.length; i++) {
        FormalParameterBuilder parameter = formals.parameters[i];
        Expression initializer = parameter.variable.initializer;
        if (parameter.isOptional || initializer != null) {
          if (!parameter.initializerWasInferred) {
            parameter.initializerWasInferred = true;
            if (parameter.isOptional) {
              initializer ??= forest.createNullLiteral(
                  // TODO(ahe): Should store: originParameter.fileOffset
                  // https://github.com/dart-lang/sdk/issues/32289
                  noLocation);
            }
            VariableDeclaration originParameter = builder.getFormalParameter(i);
            initializer = typeInferrer?.inferParameterInitializer(
                this,
                initializer,
                originParameter.type,
                parameter.hasDeclaredInitializer);
            originParameter.initializer = initializer..parent = originParameter;
            libraryBuilder.loader.transformPostInference(
                originParameter,
                transformSetLiterals,
                transformCollections,
                libraryBuilder.library);
          }

          VariableDeclaration extensionTearOffParameter =
              builder.getExtensionTearOffParameter(i);
          if (extensionTearOffParameter != null) {
            cloner ??= new CloneVisitorNotMembers();
            Expression tearOffInitializer = cloner.clone(initializer);
            extensionTearOffParameter.initializer = tearOffInitializer
              ..parent = extensionTearOffParameter;
            libraryBuilder.loader.transformPostInference(
                extensionTearOffParameter,
                transformSetLiterals,
                transformCollections,
                libraryBuilder.library);
          }
        }
      }
    }
    if (builder is ConstructorBuilder) {
      finishConstructor(builder, asyncModifier, body);
    } else if (builder is ProcedureBuilder) {
      builder.asyncModifier = asyncModifier;
    } else {
      unhandled("${builder.runtimeType}", "finishFunction", builder.charOffset,
          builder.fileUri);
    }

    InferredFunctionBody inferredFunctionBody;
    if (body != null) {
      inferredFunctionBody = typeInferrer?.inferFunctionBody(
          this,
          member.charOffset,
          _computeReturnTypeContext(member),
          asyncModifier,
          body);
      body = inferredFunctionBody.body;
      builder.function.futureValueType = inferredFunctionBody.futureValueType;
      libraryBuilder.loader.transformPostInference(body, transformSetLiterals,
          transformCollections, libraryBuilder.library);
    }

    if (builder.returnType != null) {
      checkAsyncReturnType(asyncModifier, builder.function.returnType,
          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.member.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 (FormalParameterBuilder parameter in builder.formals) {
            statements.add(parameter.variable);
          }
          statements.add(body);
          body = forest.createBlock(charOffset, noLocation, statements);
        }
        body = forest.createBlock(charOffset, noLocation, <Statement>[
          forest.createExpressionStatement(
              noLocation,
              // This error is added after type inference is done, so we
              // don't need to wrap errors in SyntheticExpressionJudgment.
              buildProblem(fasta.messageSetterWithWrongNumberOfFormals,
                  charOffset, noLength)),
          body,
        ]);
      }
    }
    // 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 (body != null) {
      if (!builder.isExternal && !isNoSuchMethodForwarder) {
        builder.body = body;
      } else {
        builder.body = new Block(<Statement>[
          new ExpressionStatement(buildProblem(
              fasta.messageExternalMethodWithBody, body.fileOffset, noLength))
            ..fileOffset = body.fileOffset,
          body,
        ])
          ..fileOffset = body.fileOffset;
      }
    }

    resolveRedirectingFactoryTargets();
    finishVariableMetadata();
  }

  void checkAsyncReturnType(AsyncMarker asyncModifier, DartType returnType,
      int charOffset, int length) {
    // For async, async*, and sync* functions with declared return types, we
    // need to determine whether those types are valid.
    // 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 = libraryBuilder.loader.futureOfBottom;
        if (!typeEnvironment.isSubtypeOf(
            futureBottomType, returnType, SubtypeCheckMode.withNullabilities)) {
          problem = fasta.messageIllegalAsyncReturnType;
        }
        break;

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

      case AsyncMarker.SyncStar:
        DartType iterableBottomType = libraryBuilder.loader.iterableOfBottom;
        if (returnType is VoidType) {
          problem = fasta.messageIllegalSyncGeneratorVoidReturnType;
        } else if (!typeEnvironment.isSubtypeOf(iterableBottomType, returnType,
            SubtypeCheckMode.withNullabilities)) {
          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, charOffset, length);
    }
  }

  /// Ensure that the containing library of the [member] has been loaded.
  ///
  /// This is for instance important for lazy dill library builders where this
  /// method has to be called to ensure that
  /// a) The library has been fully loaded (and for instance any internal
  ///    transformation needed has been performed); and
  /// b) The library is correctly marked as being used to allow for proper
  ///    'dependency pruning'.
  void ensureLoaded(Member member) {
    if (member == null) return;
    Library ensureLibraryLoaded = member.enclosingLibrary;
    LibraryBuilder builder =
        libraryBuilder.loader.builders[ensureLibraryLoaded.importUri] ??
            libraryBuilder.loader.target.dillTarget.loader
                .builders[ensureLibraryLoaded.importUri];
    if (builder is DillLibraryBuilder) {
      builder.ensureLoaded();
    }
  }

  /// Check if the containing library of the [member] has been loaded.
  ///
  /// This is designed for use with asserts.
  /// See [ensureLoaded] for a description of what 'loaded' means and the ideas
  /// behind that.
  bool isLoaded(Member member) {
    if (member == null) return true;
    Library ensureLibraryLoaded = member.enclosingLibrary;
    LibraryBuilder builder =
        libraryBuilder.loader.builders[ensureLibraryLoaded.importUri] ??
            libraryBuilder.loader.target.dillTarget.loader
                .builders[ensureLibraryLoaded.importUri];
    if (builder is DillLibraryBuilder) {
      return builder.isBuiltAndMarked;
    }
    return true;
  }

  // TODO(eernst): Rename this method now that it handles more tasks.
  void resolveRedirectingFactoryTargets() {
    _unaliasTypeAliasedConstructorInvocations();
    _unaliasTypeAliasedFactoryInvocations();
    _resolveRedirectingFactoryTargets(
        redirectingFactoryInvocations, delayedRedirectingFactoryInvocations);
  }

  /// Return an [Expression] resolving the argument invocation.
  ///
  /// The arguments specify the [StaticInvocation] whose `.target` is
  /// [target], `.arguments` is [arguments], `.fileOffset` is [fileOffset],
  /// and `.isConst` is [isConst].
  /// Returns null if the invocation can't be resolved.
  Expression _resolveRedirectingFactoryTarget(
      Procedure target, Arguments arguments, int fileOffset, bool isConst) {
    Procedure initialTarget = target;
    Expression replacementNode;

    RedirectionTarget redirectionTarget =
        getRedirectionTarget(initialTarget, this);
    Member resolvedTarget = redirectionTarget?.target;
    if (redirectionTarget != null &&
        redirectionTarget.typeArguments.any((type) => type is UnknownType)) {
      return null;
    }

    if (resolvedTarget == null) {
      String name = constructorNameForDiagnostics(initialTarget.name.text,
          className: initialTarget.enclosingClass.name);
      // TODO(dmitryas): Report this error earlier.
      replacementNode = buildProblem(
          fasta.templateCyclicRedirectingFactoryConstructors
              .withArguments(name),
          initialTarget.fileOffset,
          name.length);
    } else if (resolvedTarget is Constructor &&
        resolvedTarget.enclosingClass.isAbstract) {
      replacementNode = evaluateArgumentsBefore(
          forest.createArguments(noLocation, arguments.positional,
              types: arguments.types, named: 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 = buildProblem(
            fasta.templateMethodNotFound.withArguments(errorName),
            fileOffset,
            noLength,
            suppressMessage: true);
      } else {
        Substitution substitution = Substitution.fromPairs(
            initialTarget.function.typeParameters, arguments.types);
        arguments.types.clear();
        arguments.types.length = redirectionTarget.typeArguments.length;
        for (int i = 0; i < arguments.types.length; i++) {
          arguments.types[i] =
              substitution.substituteType(redirectionTarget.typeArguments[i]);
        }

        replacementNode = buildStaticInvocation(
            resolvedTarget,
            forest.createArguments(noLocation, arguments.positional,
                types: arguments.types,
                named: arguments.named,
                hasExplicitTypeArguments: hasExplicitTypeArguments(arguments)),
            constness:
                isConst ? Constness.explicitConst : Constness.explicitNew,
            charOffset: fileOffset);
      }
    }
    return replacementNode;
  }

  void _resolveRedirectingFactoryTargets(
      List<Expression> redirectingFactoryInvocations,
      List<Expression> delayedRedirectingFactoryInvocations) {
    for (StaticInvocation invocation in redirectingFactoryInvocations) {
      // If the invocation was invalid, it or its parent has already been
      // desugared into an exception throwing expression.  There is nothing to
      // resolve anymore.  Note that in the case where the invocation's parent
      // was invalid, type inference won't reach the invocation node and won't
      // set its inferredType field.  If type inference is disabled, reach to
      // the outermost parent to check if the node is a dead code.
      if (invocation.parent == null) continue;
      if (typeInferrer != null) {
        if (invocation is FactoryConstructorInvocationJudgment &&
            !invocation.hasBeenInferred) {
          continue;
        }
      } else {
        TreeNode parent = invocation.parent;
        while (parent is! Component && parent != null) {
          parent = parent.parent;
        }
        if (parent == null) continue;
      }
      Expression replacement = _resolveRedirectingFactoryTarget(
          invocation.target,
          invocation.arguments,
          invocation.fileOffset,
          invocation.isConst);
      if (replacement == null) {
        delayedRedirectingFactoryInvocations?.add(invocation);
      } else {
        invocation.replaceWith(replacement);
      }
    }
    redirectingFactoryInvocations.clear();
  }

  void _unaliasTypeAliasedConstructorInvocations() {
    for (TypeAliasedConstructorInvocationJudgment invocation
        in typeAliasedConstructorInvocations) {
      DartType unaliasedType = new TypedefType(
              invocation.typeAliasBuilder.typedef,
              Nullability.nonNullable,
              invocation.arguments.types)
          .unalias;
      List<DartType> invocationTypeArguments = null;
      if (unaliasedType is InterfaceType) {
        invocationTypeArguments = unaliasedType.typeArguments;
      }
      Arguments invocationArguments = forest.createArguments(
          noLocation, invocation.arguments.positional,
          types: invocationTypeArguments, named: invocation.arguments.named);
      invocation.replaceWith(new ConstructorInvocation(
          invocation.target, invocationArguments,
          isConst: invocation.isConst));
    }
    typeAliasedConstructorInvocations.clear();
  }

  void _unaliasTypeAliasedFactoryInvocations() {
    for (TypeAliasedFactoryInvocationJudgment invocation
        in typeAliasedFactoryInvocations) {
      DartType unaliasedType = new TypedefType(
              invocation.typeAliasBuilder.typedef,
              Nullability.nonNullable,
              invocation.arguments.types)
          .unalias;
      List<DartType> invocationTypeArguments = null;
      if (unaliasedType is InterfaceType) {
        invocationTypeArguments = unaliasedType.typeArguments;
      }
      Arguments invocationArguments = forest.createArguments(
          noLocation, invocation.arguments.positional,
          types: invocationTypeArguments,
          named: invocation.arguments.named,
          hasExplicitTypeArguments:
              hasExplicitTypeArguments(invocation.arguments));
      invocation.replaceWith(_resolveRedirectingFactoryTarget(invocation.target,
          invocationArguments, invocation.fileOffset, invocation.isConst));
    }
    typeAliasedFactoryInvocations.clear();
  }

  /// Perform actions that were delayed
  ///
  /// An action can be delayed, for instance, because it depends on some
  /// calculations in another library.  For example, a resolution of a
  /// redirecting factory invocation depends on the type inference in the
  /// redirecting factory.
  void performDelayedActions() {
    if (delayedRedirectingFactoryInvocations.isNotEmpty) {
      _resolveRedirectingFactoryTargets(
          delayedRedirectingFactoryInvocations, null);
      if (delayedRedirectingFactoryInvocations.isNotEmpty) {
        for (StaticInvocation invocation
            in delayedRedirectingFactoryInvocations) {
          internalProblem(
              fasta.templateInternalProblemUnhandled.withArguments(
                  invocation.target.name.text, 'performDelayedActions'),
              invocation.fileOffset,
              uri);
        }
      }
    }
  }

  bool get hasDelayedActions {
    return delayedRedirectingFactoryInvocations.isNotEmpty;
  }

  void finishVariableMetadata() {
    List<VariableDeclaration> variablesWithMetadata =
        this.variablesWithMetadata;
    this.variablesWithMetadata = null;
    List<List<VariableDeclaration>> multiVariablesWithMetadata =
        this.multiVariablesWithMetadata;
    this.multiVariablesWithMetadata = null;

    if (variablesWithMetadata != null) {
      for (int i = 0; i < variablesWithMetadata.length; i++) {
        inferAnnotations(
            variablesWithMetadata[i], variablesWithMetadata[i].annotations);
      }
    }
    if (multiVariablesWithMetadata != null) {
      for (int i = 0; i < multiVariablesWithMetadata.length; i++) {
        List<VariableDeclaration> variables = multiVariablesWithMetadata[i];
        List<Expression> annotations = variables.first.annotations;
        inferAnnotations(variables.first, annotations);
        for (int i = 1; i < variables.length; i++) {
          cloner ??= new CloneVisitorNotMembers();
          VariableDeclaration variable = variables[i];
          for (int i = 0; i < annotations.length; i++) {
            variable.addAnnotation(cloner.clone(annotations[i]));
          }
        }
      }
    }
  }

  @override
  List<Expression> finishMetadata(TreeNode parent) {
    List<Expression> expressions = pop();
    inferAnnotations(parent, 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();
    finishVariableMetadata();
    return temporaryParent != null ? temporaryParent.expressions : expressions;
  }

  @override
  Expression parseSingleExpression(
      Parser parser, Token token, FunctionNode parameters) {
    assert(redirectingFactoryInvocations.isEmpty);
    int fileOffset = offsetForToken(token);
    List<TypeVariableBuilder> typeParameterBuilders;
    for (TypeParameter typeParameter in parameters.typeParameters) {
      typeParameterBuilders ??= <TypeVariableBuilder>[];
      typeParameterBuilders.add(
          new TypeVariableBuilder.fromKernel(typeParameter, libraryBuilder));
    }
    enterFunctionTypeScope(typeParameterBuilders);

    List<FormalParameterBuilder> formals =
        parameters.positionalParameters.length == 0
            ? null
            : new List<FormalParameterBuilder>.filled(
                parameters.positionalParameters.length, null);
    for (int i = 0; i < parameters.positionalParameters.length; i++) {
      VariableDeclaration formal = parameters.positionalParameters[i];
      formals[i] = new FormalParameterBuilder(
          null, 0, null, formal.name, libraryBuilder, formal.fileOffset,
          fileUri: uri)
        ..variable = formal;
    }
    enterLocalScope(
        null,
        new FormalParameters(formals, fileOffset, 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));
    }

    ReturnStatementImpl fakeReturn = new ReturnStatementImpl(true, expression);
    if (formals != null) {
      for (int i = 0; i < formals.length; i++) {
        typeInferrer?.flowAnalysis?.declare(formals[i].variable, true);
      }
    }
    InferredFunctionBody inferredFunctionBody = typeInferrer?.inferFunctionBody(
        this, fileOffset, const DynamicType(), AsyncMarker.Sync, fakeReturn);
    assert(
        fakeReturn == inferredFunctionBody.body,
        "Previously implicit assumption about inferFunctionBody "
        "not returning anything different.");

    resolveRedirectingFactoryTargets();
    libraryBuilder.loader.transformPostInference(fakeReturn,
        transformSetLiterals, transformCollections, libraryBuilder.library);

    return fakeReturn.expression;
  }

  void parseInitializers(Token token) {
    Parser parser = new Parser(this);
    if (!token.isEof) {
      token = parser.parseInitializers(token);
      checkEmpty(token.charOffset);
    } else {
      handleNoInitializers();
    }
    // We are passing [AsyncMarker.Sync] because the error will be reported
    // already.
    finishConstructor(member, AsyncMarker.Sync, null);
  }

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

  Expression parseAnnotation(Token token) {
    Parser parser = new Parser(this);
    token = parser.parseMetadata(parser.syntheticPreviousToken(token));
    Expression annotation = pop();
    checkEmpty(token.charOffset);
    return annotation;
  }

  void finishConstructor(
      ConstructorBuilder builder, AsyncMarker asyncModifier, Statement body) {
    /// 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.actualConstructor;
    List<FormalParameterBuilder> formals = builder.formals;
    if (formals != null) {
      for (int i = 0; i < formals.length; i++) {
        FormalParameterBuilder parameter = formals[i];
        typeInferrer?.flowAnalysis?.declare(parameter.variable, true);
      }
    }
    if (_initializers != null) {
      for (Initializer initializer in _initializers) {
        typeInferrer?.inferInitializer(this, initializer);
      }
      if (!builder.isExternal) {
        for (Initializer initializer in _initializers) {
          builder.addInitializer(initializer, this);
        }
      }
    }
    if (asyncModifier != AsyncMarker.Sync) {
      constructor.initializers.add(buildInvalidInitializer(buildProblem(
          fasta.messageConstructorNotSync, body.fileOffset, noLength)));
    }
    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.createArgumentsEmpty(noLocation);
      if (superTarget == null ||
          checkArgumentsForFunction(superTarget.function, arguments,
                  builder.charOffset, const <TypeParameter>[]) !=
              null) {
        String superclass = classBuilder.supertypeBuilder.fullNameForErrors;
        int length = constructor.name.text.length;
        if (length == 0) {
          length = (constructor.parent as Class).name.length;
        }
        initializer = buildInvalidInitializer(
            buildProblem(
                fasta.templateSuperclassHasNoDefaultConstructor
                    .withArguments(superclass),
                builder.charOffset,
                length),
            builder.charOffset);
      } else {
        initializer = buildSuperInitializer(
            true, superTarget, arguments, builder.charOffset);
      }
      constructor.initializers.add(initializer);
    }
    setParents(constructor.initializers, constructor);
    libraryBuilder.loader.transformListPostInference(constructor.initializers,
        transformSetLiterals, transformCollections, libraryBuilder.library);
    if (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 handleExpressionStatement(Token token) {
    debugEvent("ExpressionStatement");
    push(forest.createExpressionStatement(
        offsetForToken(token), popForEffect()));
  }

  @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,
                  argument.fileOffset, 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.createArguments(beginToken.offset, positional, 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.createArguments(
          beginToken.offset, new List<Expression>.from(arguments)));
    }
  }

  @override
  void handleParenthesizedCondition(Token token) {
    debugEvent("ParenthesizedCondition");
    push(popForValue());
  }

  @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) {
    assert(checkState(beginToken, [
      ValueKinds.ArgumentsOrNull,
      ValueKinds.TypeArgumentsOrNull,
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.Identifier,
        ValueKinds.ParserRecovery,
        ValueKinds.ProblemBuilder
      ])
    ]));
    debugEvent("Send");
    Arguments arguments = pop();
    List<UnresolvedType> typeArguments = pop();
    Object receiver = pop();
    // Delay adding [typeArguments] to [forest] for type aliases: They
    // must be unaliased to the type arguments of the denoted type.
    bool isInForest = arguments != null &&
        typeArguments != null &&
        (receiver is! TypeUseGenerator ||
            (receiver is TypeUseGenerator &&
                receiver.declaration is! TypeAliasBuilder));
    if (isInForest) {
      assert(forest.argumentsTypeArguments(arguments).isEmpty);
      forest.argumentsSetTypeArguments(
          arguments, buildDartTypeArguments(typeArguments));
    } else {
      assert(typeArguments == null ||
          (receiver is TypeUseGenerator &&
              receiver.declaration is TypeAliasBuilder));
    }
    if (receiver is Identifier) {
      Name name = new Name(receiver.name, libraryBuilder.nameOrigin);
      if (arguments == null) {
        push(new IncompletePropertyAccessGenerator(this, beginToken, name));
      } else {
        push(new SendAccessGenerator(
            this, beginToken, name, typeArguments, arguments,
            isTypeArgumentsInForest: isInForest));
      }
    } else if (receiver is ParserRecovery) {
      push(new ParserErrorGenerator(this, null, fasta.messageSyntheticToken));
    } else if (arguments == null) {
      push(receiver);
    } else {
      push(finishSend(receiver, typeArguments, arguments, beginToken.charOffset,
          isTypeArgumentsInForest: isInForest));
    }
    assert(checkState(beginToken, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.Initializer,
        ValueKinds.ProblemBuilder
      ])
    ]));
  }

  @override
  finishSend(Object receiver, List<UnresolvedType> typeArguments,
      Arguments arguments, int charOffset,
      {bool isTypeArgumentsInForest = false}) {
    if (receiver is Generator) {
      return receiver.doInvocation(charOffset, typeArguments, arguments,
          isTypeArgumentsInForest: isTypeArgumentsInForest);
    } else {
      return forest.createExpressionInvocation(
          charOffset, toValue(receiver), arguments);
    }
  }

  @override
  void beginCascade(Token token) {
    debugEvent("beginCascade");
    Expression expression = popForValue();
    if (expression is Cascade) {
      push(expression);
      push(_createReadOnlyVariableAccess(expression.variable, token,
          expression.fileOffset, null, ReadOnlyAccessKind.LetVariable));
    } else {
      bool isNullAware = optional('?..', token);
      if (isNullAware && !libraryBuilder.isNonNullableByDefault) {
        reportMissingNonNullableSupport(token);
      }
      VariableDeclaration variable =
          createVariableDeclarationForValue(expression);
      push(new Cascade(variable, isNullAware: isNullAware)
        ..fileOffset = expression.fileOffset);
      push(_createReadOnlyVariableAccess(variable, token, expression.fileOffset,
          null, ReadOnlyAccessKind.LetVariable));
    }
  }

  @override
  void endCascade() {
    debugEvent("endCascade");
    Expression expression = popForEffect();
    Cascade cascadeReceiver = pop();
    cascadeReceiver.addCascadeExpression(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) {
    bool isAnd = optional("&&", token);
    if (isAnd || optional("||", token)) {
      Expression lhs = popForValue();
      typePromoter?.enterLogicalExpression(lhs, token.stringValue);
      // This is matched by the call to [endNode] in
      // [doLogicalExpression].
      if (isAnd) {
        typeInferrer?.assignedVariables?.beginNode();
      }
      push(lhs);
    }
  }

  @override
  void endBinaryExpression(Token token) {
    debugEvent("BinaryExpression");
    if (optional(".", token) ||
        optional("..", token) ||
        optional("?..", token)) {
      doDotOrCascadeExpression(token);
    } else if (optional("&&", token) || optional("||", token)) {
      doLogicalExpression(token);
    } else if (optional("??", token)) {
      doIfNull(token);
    } else if (optional("?.", token)) {
      doIfNotNull(token);
    } else {
      doBinaryExpression(token);
    }
  }

  void doBinaryExpression(Token token) {
    assert(checkState(token, <ValueKind>[
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
      ]),
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
      ]),
    ]));
    Expression right = popForValue();
    Object left = pop();
    int fileOffset = offsetForToken(token);
    String operator = token.stringValue;
    bool isNot = identical("!=", operator);
    if (isNot || identical("==", operator)) {
      if (left is Generator) {
        push(left.buildEqualsOperation(token, right, isNot: isNot));
      } else {
        if (left is ProblemBuilder) {
          ProblemBuilder problem = left;
          left = buildProblem(problem.message, problem.charOffset, noLength);
        }
        assert(left is Expression);
        push(forest.createEquals(fileOffset, left, right, isNot: isNot));
      }
    } else {
      Name name = new Name(operator);
      if (!isBinaryOperator(operator) && !isMinusOperator(operator)) {
        if (isUserDefinableOperator(operator)) {
          push(buildProblem(
              fasta.templateNotBinaryOperator.withArguments(token),
              token.charOffset,
              token.length));
        } else {
          push(buildProblem(fasta.templateInvalidOperator.withArguments(token),
              token.charOffset, token.length));
        }
      } else if (left is Generator) {
        push(left.buildBinaryOperation(token, name, right));
      } else {
        if (left is ProblemBuilder) {
          ProblemBuilder problem = left;
          left = buildProblem(problem.message, problem.charOffset, noLength);
        }
        assert(left is Expression);
        push(forest.createBinary(fileOffset, left, name, right));
      }
    }
  }

  /// Handle `a && b` and `a || b`.
  void doLogicalExpression(Token token) {
    Expression argument = popForValue();
    Expression receiver = pop();
    Expression logicalExpression = forest.createLogicalExpression(
        offsetForToken(token), receiver, token.stringValue, argument);
    typePromoter?.exitLogicalExpression(argument, logicalExpression);
    push(logicalExpression);
    if (optional("&&", token)) {
      // This is matched by the call to [beginNode] in
      // [beginBinaryExpression].
      typeInferrer?.assignedVariables?.endNode(logicalExpression);
    }
  }

  /// Handle `a ?? b`.
  void doIfNull(Token token) {
    Expression b = popForValue();
    Expression a = popForValue();
    push(new IfNullExpression(a, b)..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, libraryBuilder.nameOrigin);
    List<LocatedMessage> context;
    if (candidate != null && candidate.location != null) {
      Uri uri = candidate.location.file;
      int offset = candidate.fileOffset;
      Message contextMessage;
      int length = noLength;
      if (candidate is Constructor && candidate.isSynthetic) {
        offset = candidate.enclosingClass.fileOffset;
        contextMessage = fasta.templateCandidateFoundIsDefaultConstructor
            .withArguments(candidate.enclosingClass.name);
      } else {
        if (candidate is Constructor) {
          if (candidate.name.text == '') {
            length = candidate.enclosingClass.name.length;
          } else {
            // Assume no spaces around the dot. Not perfect, but probably the
            // best we can do with the information available.
            length = candidate.enclosingClass.name.length + 1 + name.length;
          }
        } 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);
      }
    }
    return buildProblem(
        message.messageObject, message.charOffset, message.length,
        context: context);
  }

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

  @override
  Message warnUnresolvedMethod(Name name, int charOffset,
      {bool isSuper: false,
      bool reportWarning: true,
      List<LocatedMessage> context}) {
    String plainName = name.text;
    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.text)
        : fasta.templateMethodNotFound.withArguments(name.text);
    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}) {
    return classBuilder.lookupInstanceMember(hierarchy, name,
        isSetter: isSetter, isSuper: isSuper);
  }

  @override
  Constructor lookupConstructor(Name name, {bool isSuper}) {
    return classBuilder.lookupConstructor(name, isSuper: isSuper);
  }

  @override
  void handleIdentifier(Token token, IdentifierContext context) {
    debugEvent("handleIdentifier");
    String name = token.lexeme;
    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
            : !member.isStatic &&
                    classBuilder != null &&
                    classBuilder.declaresConstConstructor
                ? ConstantContext.required
                : 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(token));
    }
  }

  /// Helper method to create a [VariableGet] of the [variable] using
  /// [charOffset] as the file offset.
  @override
  VariableGet createVariableGet(VariableDeclaration variable, int charOffset,
      {bool forNullGuardedAccess: false}) {
    if (!(variable as VariableDeclarationImpl).isLocalFunction) {
      typeInferrer?.assignedVariables?.read(variable);
    }
    Object fact =
        typePromoter?.getFactForAccess(variable, functionNestingLevel);
    Object scope = typePromoter?.currentScope;
    return new VariableGetImpl(variable, fact, scope,
        forNullGuardedAccess: forNullGuardedAccess)
      ..fileOffset = charOffset;
  }

  /// Helper method to create a [ReadOnlyAccessGenerator] on the [variable]
  /// using [token] and [charOffset] for offset information and [name]
  /// for `ExpressionGenerator._plainNameForRead`.
  ReadOnlyAccessGenerator _createReadOnlyVariableAccess(
      VariableDeclaration variable,
      Token token,
      int charOffset,
      String name,
      ReadOnlyAccessKind kind) {
    return new ReadOnlyAccessGenerator(
        this, token, createVariableGet(variable, charOffset), name, kind);
  }

  /// 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);
    }
    Builder declaration = scope.lookup(name, charOffset, uri);
    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, libraryBuilder);
    }
    if (declaration != null &&
        declaration.isDeclarationInstanceMember &&
        (inFieldInitializer && !inLateFieldInitializer) &&
        !inInitializer) {
      // We cannot access a class instance member in an initializer of a
      // field.
      //
      // For instance
      //
      //     class M {
      //       int foo = bar;
      //       int bar;
      //     }
      //
      return new IncompleteErrorGenerator(this, token,
          fasta.templateThisAccessInFieldInitializer.withArguments(name));
    }
    if (declaration == null ||
        (!isDeclarationInstanceContext &&
            declaration.isDeclarationInstanceMember)) {
      // We either didn't find a declaration or found an instance member from
      // a non-instance context.
      Name n = new Name(name, libraryBuilder.nameOrigin);
      if (!isQualified && isDeclarationInstanceContext) {
        assert(declaration == null);
        if (constantContext != ConstantContext.none ||
            (inFieldInitializer && !inLateFieldInitializer) && !inInitializer) {
          return new UnresolvedNameGenerator(this, token, n);
        }
        if (extensionThis != null) {
          // If we are in an extension instance member we interpret this as an
          // implicit access on the 'this' parameter.
          return PropertyAccessGenerator.make(this, token,
              createVariableGet(extensionThis, charOffset), n, false);
        } else {
          // This is an implicit access on 'this'.
          return new ThisPropertyAccessGenerator(this, token, n);
        }
      } else if (ignoreMainInGetMainClosure &&
          name == "main" &&
          member?.name == "_getMainClosure") {
        return forest.createNullLiteral(charOffset);
      } else {
        return new UnresolvedNameGenerator(this, token, n);
      }
    } else if (declaration.isTypeDeclaration) {
      if (declaration is AccessErrorBuilder) {
        AccessErrorBuilder accessError = declaration;
        declaration = accessError.builder;
      }
      return new TypeUseGenerator(this, token, declaration, name);
    } else if (declaration.isLocal) {
      VariableBuilder variableBuilder = declaration;
      if (constantContext != ConstantContext.none &&
          !variableBuilder.isConst &&
          !member.isConstructor &&
          !enableConstFunctionsInLibrary) {
        return new IncompleteErrorGenerator(
            this, token, fasta.messageNotAConstantExpression);
      }
      VariableDeclaration variable = variableBuilder.variable;
      if (!variableBuilder.isAssignable) {
        return _createReadOnlyVariableAccess(
            variable,
            token,
            charOffset,
            name,
            variableBuilder.isConst
                ? ReadOnlyAccessKind.ConstVariable
                : ReadOnlyAccessKind.FinalVariable);
      } else {
        return new VariableUseGenerator(this, token, variable);
      }
    } else if (declaration.isClassInstanceMember) {
      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, libraryBuilder.nameOrigin);
      return new ThisPropertyAccessGenerator(this, token, n);
    } else if (declaration.isExtensionInstanceMember) {
      ExtensionBuilder extensionBuilder = declarationBuilder;
      MemberBuilder setterBuilder =
          _getCorrespondingSetterBuilder(scope, declaration, name, charOffset);
      // TODO(johnniwinther): Check for constantContext like below?
      if (declaration.isField) {
        declaration = null;
      }
      if (setterBuilder != null &&
          (setterBuilder.isField || setterBuilder.isStatic)) {
        setterBuilder = null;
      }
      if (declaration == null && setterBuilder == null) {
        return new UnresolvedNameGenerator(
            this, token, new Name(name, libraryBuilder.nameOrigin));
      }
      MemberBuilder getterBuilder =
          declaration is MemberBuilder ? declaration : null;
      return new ExtensionInstanceAccessGenerator.fromBuilder(
          this,
          token,
          extensionBuilder.extension,
          name,
          extensionThis,
          extensionTypeParameters,
          getterBuilder,
          setterBuilder);
    } else if (declaration.isRegularMethod) {
      assert(declaration.isStatic || declaration.isTopLevel);
      MemberBuilder memberBuilder = declaration;
      return new StaticAccessGenerator(
          this, token, name, memberBuilder.member, 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;
    } else {
      MemberBuilder setterBuilder =
          _getCorrespondingSetterBuilder(scope, declaration, name, charOffset);
      MemberBuilder getterBuilder =
          declaration is MemberBuilder ? declaration : null;
      assert(getterBuilder != null || setterBuilder != null);
      StaticAccessGenerator generator = new StaticAccessGenerator.fromBuilder(
          this, name, token, getterBuilder, setterBuilder);
      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;
    }
  }

  /// Returns the setter builder corresponding to [declaration] using the
  /// [name] and [charOffset] for the lookup into [scope] if necessary.
  MemberBuilder _getCorrespondingSetterBuilder(
      Scope scope, Builder declaration, String name, int charOffset) {
    Builder setter;
    if (declaration.isSetter) {
      setter = declaration;
    } else if (declaration.isGetter) {
      setter = scope.lookupSetter(name, charOffset, uri);
    } else if (declaration.isField) {
      MemberBuilder fieldBuilder = declaration;
      if (!fieldBuilder.isAssignable) {
        setter = scope.lookupSetter(name, charOffset, uri);
      } else {
        setter = declaration;
      }
    }
    return setter is MemberBuilder ? setter : null;
  }

  @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.createStringLiteral(offsetForToken(token), value));
    } 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.createStringLiteral(offsetForToken(first), value));
        }
      }
      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.createStringLiteral(offsetForToken(part), value));
          }
        } else {
          expressions.add(toValue(part));
        }
      }
      // Contains more than just \' or \".
      if (last.lexeme.length > 1) {
        String value = unescapeLastStringPart(
            last.lexeme, quote, last, last.isSynthetic, this);
        if (value.isNotEmpty) {
          expressions
              .add(forest.createStringLiteral(offsetForToken(last), value));
        }
      }
      push(forest.createStringConcatenation(
          offsetForToken(endToken), expressions));
    }
  }

  @override
  void handleNativeClause(Token nativeToken, bool hasName) {
    debugEvent("NativeClause");
    if (hasName) {
      pop() as StringLiteral;
    }
  }

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

  @override
  void handleStringJuxtaposition(Token startToken, 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.createStringConcatenation(
        offsetForToken(startToken), expressions ?? parts));
  }

  @override
  void handleLiteralInt(Token token) {
    debugEvent("LiteralInt");
    int value = int.tryParse(token.lexeme);
    // 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.createIntLiteralLarge(offsetForToken(token), token.lexeme));
    } else {
      push(forest.createIntLiteral(offsetForToken(token), value, token.lexeme));
    }
  }

  @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.createReturnStatement(offsetForToken(beginToken), expression,
          isArrow: !identical(beginToken.lexeme, "return")));
    }
  }

  @override
  void beginThenStatement(Token token) {
    Expression condition = popForValue();
    enterThenForTypePromotion(condition);
    // This is matched by the call to [deferNode] in
    // [endThenStatement].
    typeInferrer?.assignedVariables?.beginNode();
    push(condition);
    super.beginThenStatement(token);
  }

  @override
  void endThenStatement(Token token) {
    typePromoter?.enterElse();
    super.endThenStatement(token);
    // This is matched by the call to [beginNode] in
    // [beginThenStatement] and by the call to [storeInfo] in
    // [endIfStatement].
    push(typeInferrer?.assignedVariables?.deferNode());
  }

  @override
  void endIfStatement(Token ifToken, Token elseToken) {
    Statement elsePart = popStatementIfNotNull(elseToken);
    AssignedVariablesNodeInfo<VariableDeclaration> assignedVariablesInfo =
        pop();
    Statement thenPart = popStatement();
    Expression condition = pop();
    typePromoter?.exitConditional();
    Statement node = forest.createIfStatement(
        offsetForToken(ifToken), condition, thenPart, elsePart);
    // This is matched by the call to [deferNode] in
    // [endThenStatement].
    typeInferrer?.assignedVariables?.storeInfo(node, assignedVariablesInfo);
    push(node);
  }

  @override
  void beginVariableInitializer(Token token) {
    if ((currentLocalVariableModifiers & lateMask) != 0) {
      // This is matched by the call to [endNode] in [endVariableInitializer].
      typeInferrer?.assignedVariables?.beginNode();
    }
  }

  @override
  void endVariableInitializer(Token assignmentOperator) {
    debugEvent("VariableInitializer");
    assert(assignmentOperator.stringValue == "=");
    AssignedVariablesNodeInfo<VariableDeclaration> assignedVariablesInfo;
    bool isLate = (currentLocalVariableModifiers & lateMask) != 0;
    Expression initializer = popForValue();
    if (isLate) {
      assignedVariablesInfo = typeInferrer?.assignedVariables
          ?.deferNode(isClosureOrLateVariableInitializer: true);
    }
    pushNewLocalVariable(initializer, equalsToken: assignmentOperator);
    if (isLate) {
      VariableDeclaration node = peek();
      // This is matched by the call to [beginNode] in
      // [beginVariableInitializer].
      typeInferrer?.assignedVariables?.storeInfo(node, assignedVariablesInfo);
    }
  }

  @override
  void handleNoVariableInitializer(Token token) {
    debugEvent("NoVariableInitializer");
    bool isConst = (currentLocalVariableModifiers & constMask) != 0;
    bool isFinal = (currentLocalVariableModifiers & finalMask) != 0;
    bool isLate = (currentLocalVariableModifiers & lateMask) != 0;
    Expression initializer;
    if (!optional("in", token.next)) {
      // 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 (!token.isSynthetic) {
        // If [token] is synthetic it is created from error recovery.
        if (isConst) {
          initializer = buildProblem(
              fasta.templateConstFieldWithoutInitializer
                  .withArguments(token.lexeme),
              token.charOffset,
              token.length);
        } else if (!libraryBuilder.isNonNullableByDefault &&
            isFinal &&
            !isLate) {
          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;
    bool isLate = (currentLocalVariableModifiers & lateMask) != 0;
    bool isRequired = (currentLocalVariableModifiers & requiredMask) != 0;
    assert(isConst == (constantContext == ConstantContext.inferred));
    VariableDeclaration variable = new VariableDeclarationImpl(
        identifier.name, functionNestingLevel,
        forSyntheticToken: identifier.token.isSynthetic,
        initializer: initializer,
        type: buildDartType(currentLocalVariableType),
        isFinal: isFinal,
        isConst: isConst,
        isLate: isLate,
        isRequired: isRequired,
        hasDeclaredInitializer: initializer != null,
        isStaticLate: libraryBuilder.isNonNullableByDefault &&
            isFinal &&
            initializer == null)
      ..fileOffset = identifier.charOffset
      ..fileEqualsOffset = offsetForToken(equalsToken);
    typeInferrer?.assignedVariables?.declare(variable);
    libraryBuilder.checkBoundsInVariableDeclaration(
        variable, typeEnvironment, uri);
    push(variable);
  }

  @override
  void beginFieldInitializer(Token token) {
    inFieldInitializer = true;
    if (member is FieldBuilder) {
      FieldBuilder fieldBuilder = member;
      inLateFieldInitializer = fieldBuilder.isLate;
      if (fieldBuilder.isAbstract) {
        addProblem(
            fasta.messageAbstractFieldInitializer, token.charOffset, noLength);
      } else if (fieldBuilder.isExternal) {
        addProblem(
            fasta.messageExternalFieldInitializer, token.charOffset, noLength);
      }
    } else {
      inLateFieldInitializer = false;
    }
  }

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

  @override
  void handleNoFieldInitializer(Token token) {
    debugEvent("NoFieldInitializer");
    if (constantContext == ConstantContext.inferred) {
      // Creating a null value to prevent the Dart VM from crashing.
      push(forest.createNullLiteral(offsetForToken(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 lateToken, Token varFinalOrConst) {
    debugEvent("beginVariablesDeclaration");
    if (!libraryBuilder.isNonNullableByDefault) {
      reportNonNullableModifierError(lateToken);
    }
    UnresolvedType type = pop();
    int modifiers = (lateToken != null ? lateMask : 0) |
        Modifier.validateVarFinalOrConst(varFinalOrConst?.lexeme);
    _enterLocalState(inLateLocalInitializer: lateToken != null);
    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 (int i = 0; i < annotations.length; i++) {
          variable.addAnnotation(annotations[i]);
        }
        (variablesWithMetadata ??= <VariableDeclaration>[]).add(variable);
      }
      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) {
        VariableDeclaration first = variables.first;
        for (int i = 0; i < annotations.length; i++) {
          first.addAnnotation(annotations[i]);
        }
        (multiVariablesWithMetadata ??= <List<VariableDeclaration>>[])
            .add(variables);
      }
      push(forest.variablesDeclaration(variables, uri));
    }
    _exitLocalState();
  }

  /// Stack containing assigned variables info for try statements.
  ///
  /// These are created in [beginTryStatement] and ended in either [beginBlock]
  /// when a finally block starts or in [endTryStatement] when the try statement
  /// ends. Since these need to be associated with the try statement created in
  /// in [endTryStatement] we store them the stack until the try statement is
  /// created.
  Link<AssignedVariablesNodeInfo<VariableDeclaration>> tryStatementInfoStack =
      const Link<AssignedVariablesNodeInfo<VariableDeclaration>>();

  @override
  void beginBlock(Token token, BlockKind blockKind) {
    if (blockKind == BlockKind.tryStatement) {
      // This is matched by the call to [endNode] in [endBlock].
      typeInferrer?.assignedVariables?.beginNode();
    } else if (blockKind == BlockKind.finallyClause) {
      // This is matched by the call to [beginNode] in [beginTryStatement].
      tryStatementInfoStack = tryStatementInfoStack
          .prepend(typeInferrer?.assignedVariables?.deferNode());
    }
    super.beginBlock(token, blockKind);
  }

  @override
  void endBlock(
      int count, Token openBrace, Token closeBrace, BlockKind blockKind) {
    debugEvent("Block");
    Statement block = popBlock(count, openBrace, closeBrace);
    exitLocalScope();
    push(block);
    if (blockKind == BlockKind.tryStatement) {
      // This is matched by the call to [beginNode] in [beginBlock].
      typeInferrer?.assignedVariables?.endNode(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) {
    assert(checkState(token, [
      unionOfKinds(<ValueKind>[
        ValueKinds.Expression,
        ValueKinds.Generator,
        // TODO(johnniwinther): Avoid problem builders here.
        ValueKinds.ProblemBuilder
      ]),
      unionOfKinds(<ValueKind>[
        ValueKinds.Expression, ValueKinds.Generator,
        // TODO(johnniwinther): Avoid problem builders here.
        ValueKinds.ProblemBuilder
      ])
    ]));
    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> _buildForLoopVariableDeclarations(
      variableOrExpression) {
    // TODO(ahe): This can be simplified now that we have the events
    // `handleForInitializer...` events.
    if (variableOrExpression is Generator) {
      variableOrExpression = variableOrExpression.buildForEffect();
    }
    if (variableOrExpression is VariableDeclaration) {
      // Late for loop variables are not supported. An error has already been
      // reported by the parser.
      variableOrExpression.isLate = false;
      return <VariableDeclaration>[variableOrExpression];
    } else if (variableOrExpression is Expression) {
      VariableDeclaration variable =
          new VariableDeclarationImpl.forEffect(variableOrExpression);
      return <VariableDeclaration>[variable];
    } else if (variableOrExpression is ExpressionStatement) {
      VariableDeclaration variable = new VariableDeclarationImpl.forEffect(
          variableOrExpression.expression);
      return <VariableDeclaration>[variable];
    } 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(_buildForLoopVariableDeclarations(v));
      }
      return variables;
    } else if (variableOrExpression == null) {
      return <VariableDeclaration>[];
    }
    return null;
  }

  @override
  void handleForInitializerEmptyStatement(Token token) {
    debugEvent("ForInitializerEmptyStatement");
    push(NullValue.Expression);
    // This is matched by the call to [deferNode] in [endForStatement] or
    // [endForControlFlow].
    typeInferrer?.assignedVariables?.beginNode();
  }

  @override
  void handleForInitializerExpressionStatement(Token token, bool forIn) {
    debugEvent("ForInitializerExpressionStatement");
    if (!forIn) {
      // This is matched by the call to [deferNode] in [endForStatement] or
      // [endForControlFlow].
      typeInferrer?.assignedVariables?.beginNode();
    }
  }

  @override
  void handleForInitializerLocalVariableDeclaration(Token token, bool forIn) {
    debugEvent("ForInitializerLocalVariableDeclaration");
    if (forIn) {
      // If the declaration is of the form `for (final x in ...)`, then we may
      // have erroneously set the `isStaticLate` flag, so un-set it.
      Object declaration = peek();
      if (declaration is VariableDeclarationImpl) {
        declaration.isStaticLate = false;
      }
    } else {
      // This is matched by the call to [deferNode] in [endForStatement] or
      // [endForControlFlow].
      typeInferrer?.assignedVariables?.beginNode();
    }
  }

  @override
  void handleForLoopParts(Token forKeyword, Token leftParen,
      Token leftSeparator, int updateExpressionCount) {
    push(forKeyword);
    push(leftParen);
    push(leftSeparator);
    push(updateExpressionCount);
  }

  @override
  void endForControlFlow(Token token) {
    debugEvent("ForControlFlow");
    Object entry = pop();
    int updateExpressionCount = pop();
    pop(); // left separator
    pop(); // left parenthesis
    Token forToken = pop();
    List<Expression> updates = popListForEffect(updateExpressionCount);
    Statement conditionStatement = popStatement(); // condition

    if (constantContext != ConstantContext.none) {
      pop(); // Pop variable or expression.
      exitLocalScope();
      typeInferrer?.assignedVariables?.discardNode();

      handleRecoverableError(
          fasta.templateCantUseControlFlowOrSpreadAsConstant
              .withArguments(forToken),
          forToken,
          forToken);