pkg/front_end/lib/src/kernel/body_builder.dart

// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

library fasta.body_builder;

import 'package:_fe_analyzer_shared/src/messages/severity.dart' show Severity;
import 'package:_fe_analyzer_shared/src/parser/parser.dart'
    show
        Assert,
        BlockKind,
        ConstructorReferenceContext,
        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/stack_listener.dart'
    show FixedNullableList, GrowableList, NullValues, ParserRecovery;
import 'package:_fe_analyzer_shared/src/parser/util.dart' show stripSeparators;
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/type_inference/assigned_variables.dart';
import 'package:_fe_analyzer_shared/src/util/link.dart';
import 'package:_fe_analyzer_shared/src/util/value_kind.dart';
import 'package:kernel/ast.dart';
import 'package:kernel/class_hierarchy.dart';
import 'package:kernel/clone.dart';
import 'package:kernel/core_types.dart';
import 'package:kernel/names.dart' show emptyName, minusName, plusName;
import 'package:kernel/src/bounds_checks.dart' hide calculateBounds;
import 'package:kernel/type_algebra.dart';
import 'package:kernel/type_environment.dart';

import '../api_prototype/experimental_flags.dart';
import '../api_prototype/lowering_predicates.dart';
import '../base/constant_context.dart' show ConstantContext;
import '../base/identifiers.dart'
    show
        Identifier,
        InitializedIdentifier,
        QualifiedName,
        SimpleIdentifier,
        flattenName;
import '../base/label_scope.dart';
import '../base/local_scope.dart';
import '../base/modifier.dart'
    show Modifier, constMask, covariantMask, finalMask, lateMask, requiredMask;
import '../base/problems.dart' show internalProblem, unhandled, unsupported;
import '../base/scope.dart';
import '../builder/builder.dart';
import '../builder/declaration_builders.dart';
import '../builder/formal_parameter_builder.dart';
import '../builder/function_type_builder.dart';
import '../builder/invalid_type_builder.dart';
import '../builder/library_builder.dart';
import '../builder/member_builder.dart';
import '../builder/named_type_builder.dart';
import '../builder/nullability_builder.dart';
import '../builder/omitted_type_builder.dart';
import '../builder/prefix_builder.dart';
import '../builder/record_type_builder.dart';
import '../builder/type_builder.dart';
import '../builder/variable_builder.dart';
import '../builder/void_type_declaration_builder.dart';
import '../codes/cfe_codes.dart'
    show
        LocatedMessage,
        Message,
        Template,
        messageNamedFieldClashesWithPositionalFieldInRecord,
        noLength,
        templateDuplicatedRecordLiteralFieldName,
        templateDuplicatedRecordLiteralFieldNameContext,
        templateExperimentNotEnabledOffByDefault,
        templateLocalVariableUsedBeforeDeclared,
        templateLocalVariableUsedBeforeDeclaredContext;
import '../codes/cfe_codes.dart' as fasta;
import '../dill/dill_library_builder.dart' show DillLibraryBuilder;
import '../source/diet_parser.dart';
import '../source/source_field_builder.dart';
import '../source/source_library_builder.dart';
import '../source/source_member_builder.dart';
import '../source/stack_listener_impl.dart'
    show StackListenerImpl, offsetForToken;
import '../source/value_kinds.dart';
import '../type_inference/inference_results.dart'
    show InitializerInferenceResult;
import '../type_inference/type_inferrer.dart'
    show TypeInferrer, InferredFunctionBody;
import '../type_inference/type_schema.dart' show UnknownType;
import '../util/helpers.dart';
import '../util/local_stack.dart';
import 'benchmarker.dart' show Benchmarker;
import 'body_builder_context.dart';
import 'collections.dart';
import 'constness.dart' show Constness;
import 'expression_generator.dart';
import 'expression_generator_helper.dart';
import 'forest.dart' show Forest;
import 'implicit_type_argument.dart' show ImplicitTypeArgument;
import 'internal_ast.dart';
import 'kernel_variable_builder.dart';
import 'load_library_builder.dart';
import 'type_algorithms.dart' show calculateBounds;
import 'utils.dart';

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

enum JumpTargetKind {
  Break,
  Continue,
  Goto, // Continue label in switch.
}

class BodyBuilder extends StackListenerImpl
    implements ExpressionGeneratorHelper {
  @override
  final Forest forest;

  @override
  final SourceLibraryBuilder libraryBuilder;

  final BodyBuilderContext _context;

  final ClassHierarchy hierarchy;

  final CoreTypes coreTypes;

  final LocalScope enclosingScope;

  final bool enableNative;

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

  final TypeInferrer typeInferrer;

  final Benchmarker? benchmarker;

  /// 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;

  LocalScope? 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 inInitializerLeftHandSide = false;

  /// This is set to true when we are parsing constructor initializers.
  bool inConstructorInitializer = false;

  /// This is set to `true` when we are parsing formals.
  bool inFormals = 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;

  /// Level of nesting of function-type type parameters.
  ///
  /// For instance, `X` is at nesting level 1, and `Y` is at nesting level 2 in
  /// the following:
  ///
  ///    method() {
  ///      Function<X>(Function<Y extends X>(Y))? f;
  ///    }
  ///
  /// For simplicity, non-generic functions are considered generic functions
  /// with 0 type parameters.
  int _structuralParameterDepthLevel = 0;

  /// True if a type of a formal parameter is currently compiled.
  ///
  /// This variable is needed to distinguish between the type of a formal
  /// parameter and its initializer because in those two regions of code the
  /// type variables should be interpreted differently: as structural and
  /// nominal correspondingly.
  bool _insideOfFormalParameterType = false;

  bool get inFunctionType =>
      _structuralParameterDepthLevel > 0 || _insideOfFormalParameterType;

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

  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;

  Statement? problemInLoopOrSwitch;

  LocalStack<LabelScope> _labelScopes;

  LocalStack<LabelScope?> _switchScopes = new LocalStack([]);

  late _BodyBuilderCloner _cloner = new _BodyBuilderCloner(this);

  @override
  ConstantContext constantContext = ConstantContext.none;

  DartType? 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;

  /// 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 or
  /// an instance member or constructor in and extension type declaration,
  /// [thisVariable] holds the synthetically added variable holding the value
  /// for `this`.
  final VariableDeclaration? thisVariable;

  final List<TypeParameter>? thisTypeParameters;

  LocalStack<LocalScope> _localScopes;

  Set<VariableDeclaration>? declaredInCurrentGuard;

  JumpTarget? breakTarget;

  JumpTarget? continueTarget;

  /// Index for building unique lowered names for wildcard variables.
  int wildcardVariableIndex = 0;

  BodyBuilder(
      {required this.libraryBuilder,
      required BodyBuilderContext context,
      required this.enclosingScope,
      this.formalParameterScope,
      required this.hierarchy,
      required this.coreTypes,
      this.thisVariable,
      this.thisTypeParameters,
      required this.uri,
      required this.typeInferrer})
      : _context = context,
        forest = const Forest(),
        enableNative = libraryBuilder.loader.target.backendTarget
            .enableNative(libraryBuilder.importUri),
        needsImplicitSuperInitializer =
            context.needsImplicitSuperInitializer(coreTypes),
        benchmarker = libraryBuilder.loader.target.benchmarker,
        _localScopes = new LocalStack([enclosingScope]),
        _labelScopes = new LocalStack([new LabelScopeImpl()]) {
    if (formalParameterScope != null) {
      for (Builder builder in formalParameterScope!.localVariables) {
        if (builder is VariableBuilder) {
          typeInferrer.assignedVariables.declare(builder.variable!);
        }
      }
    }
    if (thisVariable != null && context.isConstructor) {
      // The this variable is not part of the [formalParameterScope] in
      // constructors.
      typeInferrer.assignedVariables.declare(thisVariable!);
    }
  }

  BodyBuilder.forField(
      SourceLibraryBuilder libraryBuilder,
      BodyBuilderContext bodyBuilderContext,
      LookupScope enclosingScope,
      TypeInferrer typeInferrer,
      Uri uri)
      : this(
            libraryBuilder: libraryBuilder,
            context: bodyBuilderContext,
            enclosingScope: new EnclosingLocalScope(enclosingScope),
            formalParameterScope: null,
            hierarchy: libraryBuilder.loader.hierarchy,
            coreTypes: libraryBuilder.loader.coreTypes,
            thisVariable: null,
            uri: uri,
            typeInferrer: typeInferrer);

  BodyBuilder.forOutlineExpression(SourceLibraryBuilder library,
      BodyBuilderContext bodyBuilderContext, LookupScope scope, Uri fileUri,
      {LocalScope? formalParameterScope})
      : this(
            libraryBuilder: library,
            context: bodyBuilderContext,
            enclosingScope: new EnclosingLocalScope(scope),
            formalParameterScope: formalParameterScope,
            hierarchy: library.loader.hierarchy,
            coreTypes: library.loader.coreTypes,
            thisVariable: null,
            uri: fileUri,
            typeInferrer: library.loader.typeInferenceEngine
                .createLocalTypeInferrer(
                    fileUri, bodyBuilderContext.thisType, library, null));

  LocalScope get _localScope => _localScopes.current;

  LabelScope get _labelScope => _labelScopes.current;

  LabelScope? get _switchScope =>
      _switchScopes.hasCurrent ? _switchScopes.current : null;

  @override
  LibraryFeatures get libraryFeatures => libraryBuilder.libraryFeatures;

  @override
  // Coverage-ignore(suite): Not run.
  bool get isDartLibrary =>
      libraryBuilder.origin.importUri.isScheme("dart") ||
      uri.isScheme("org-dartlang-sdk");

  @override
  Message reportFeatureNotEnabled(
      LibraryFeature feature, int charOffset, int length) {
    return libraryBuilder.reportFeatureNotEnabled(
        feature, uri, charOffset, length);
  }

  JumpTarget createBreakTarget(int charOffset) {
    return createJumpTarget(JumpTargetKind.Break, charOffset);
  }

  JumpTarget createContinueTarget(int charOffset) {
    return createJumpTarget(JumpTargetKind.Continue, charOffset);
  }

  JumpTarget createGotoTarget(int charOffset) {
    return createJumpTarget(JumpTargetKind.Goto, charOffset);
  }

  void enterLocalScope(LocalScope localScope) {
    _localScopes.push(localScope);
    _labelScopes.push(new LabelScopeImpl(_labelScope));
  }

  void createAndEnterLocalScope(
      {required String debugName, required ScopeKind kind}) {
    _localScopes
        .push(_localScope.createNestedScope(debugName: debugName, kind: kind));
    _labelScopes.push(new LabelScopeImpl(_labelScope));
  }

  void exitLocalScope({List<ScopeKind>? expectedScopeKinds}) {
    assert(
        expectedScopeKinds == null ||
            expectedScopeKinds.contains(_localScope.kind),
        // Coverage-ignore(suite): Not run.
        "Expected the current scope to be one of the kinds "
        "${expectedScopeKinds.map((k) => "'${k}'").join(", ")}, "
        "but got '${_localScope.kind}'.");
    if (isGuardScope(_localScope) && declaredInCurrentGuard != null) {
      for (Builder builder in _localScope.localVariables) {
        if (builder is VariableBuilder) {
          declaredInCurrentGuard!.remove(builder.variable);
        }
      }
      if (declaredInCurrentGuard!.isEmpty) {
        declaredInCurrentGuard = null;
      }
    }
    _labelScopes.pop();
    _localScopes.pop();
  }

  void enterBreakTarget(int charOffset, [JumpTarget? target]) {
    push(breakTarget ?? NullValues.BreakTarget);
    breakTarget = target ?? createBreakTarget(charOffset);
  }

  void enterContinueTarget(int charOffset, [JumpTarget? target]) {
    push(continueTarget ?? NullValues.ContinueTarget);
    continueTarget = target ?? createContinueTarget(charOffset);
  }

  JumpTarget? exitBreakTarget() {
    JumpTarget? current = breakTarget;
    breakTarget = pop() as JumpTarget?;
    return current;
  }

  JumpTarget? exitContinueTarget() {
    JumpTarget? current = continueTarget;
    continueTarget = pop() as JumpTarget?;
    return current;
  }

  @override
  void beginBlockFunctionBody(Token begin) {
    debugEvent("beginBlockFunctionBody");
    createAndEnterLocalScope(
        debugName: "block function body", kind: ScopeKind.functionBody);
  }

  @override
  void beginForStatement(Token token) {
    debugEvent("beginForStatement");
    enterLoop(token.charOffset);
    createAndEnterLocalScope(
        debugName: "for statement", kind: ScopeKind.forStatement);
  }

  @override
  void beginForControlFlow(Token? awaitToken, Token forToken) {
    debugEvent("beginForControlFlow");
    createAndEnterLocalScope(
        debugName: "for in a collection", kind: ScopeKind.forStatement);
  }

  @override
  void beginDoWhileStatementBody(Token token) {
    debugEvent("beginDoWhileStatementBody");
    createAndEnterLocalScope(
        debugName: "do-while statement body",
        kind: ScopeKind.statementLocalScope);
  }

  @override
  void endDoWhileStatementBody(Token token) {
    debugEvent("endDoWhileStatementBody");
    Object? body = pop();
    exitLocalScope();
    push(body);
  }

  @override
  void beginWhileStatementBody(Token token) {
    debugEvent("beginWhileStatementBody");
    createAndEnterLocalScope(
        debugName: "while statement body", kind: ScopeKind.statementLocalScope);
  }

  @override
  void endWhileStatementBody(Token endToken) {
    debugEvent("endWhileStatementBody");
    Object? body = pop();
    exitLocalScope();
    push(body);
  }

  @override
  void beginForStatementBody(Token token) {
    debugEvent("beginForStatementBody");
    createAndEnterLocalScope(
        debugName: "for statement body", kind: ScopeKind.statementLocalScope);
  }

  @override
  void endForStatementBody(Token endToken) {
    debugEvent("endForStatementBody");
    Object? body = pop();
    exitLocalScope();
    push(body);
  }

  @override
  void beginForInBody(Token token) {
    debugEvent("beginForInBody");
    createAndEnterLocalScope(
        debugName: "for-in body", kind: ScopeKind.statementLocalScope);
  }

  @override
  void endForInBody(Token endToken) {
    debugEvent("endForInBody");
    Object? body = pop();
    exitLocalScope();
    push(body);
  }

  @override
  void beginElseStatement(Token token) {
    debugEvent("beginElseStatement");
    createAndEnterLocalScope(
        debugName: "else", kind: ScopeKind.statementLocalScope);
  }

  @override
  void endElseStatement(Token beginToken, Token endToken) {
    debugEvent("endElseStatement");
    Object? body = pop();
    exitLocalScope();
    push(body);
  }

  bool get inConstructor {
    return functionNestingLevel == 0 && _context.isConstructor;
  }

  bool get isDeclarationInstanceContext {
    return _context.isDeclarationInstanceContext;
  }

  @override
  InstanceTypeVariableAccessState get instanceTypeVariableAccessState {
    return _context.instanceTypeVariableAccessState;
  }

  @override
  TypeEnvironment get typeEnvironment => typeInferrer.typeSchemaEnvironment;

  DartType get implicitTypeArgument => const ImplicitTypeArgument();

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

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

  @override
  void registerVariableAssignment(VariableDeclaration variable) {
    typeInferrer.assignedVariables.write(variable);
  }

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

  @override
  void push(Object? node) {
    if (node is DartType) {
      unhandled("DartType", "push", -1, uri);
    }
    inInitializerLeftHandSide = 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);
  }

  Pattern toPattern(Object? node) {
    if (node is Pattern) {
      return node;
    } else if (node is Generator) {
      return forest.createConstantPattern(node.buildSimpleRead());
    } else if (node is Expression) {
      return forest.createConstantPattern(node);
    }
    // Coverage-ignore(suite): Not run.
    else if (node is ProblemBuilder) {
      // ignore: unused_local_variable
      Expression expression =
          buildProblem(node.message, node.charOffset, noLength);
      return forest.createConstantPattern(expression);
    } else {
      return unhandled("${node.runtimeType}", "toPattern", -1, uri);
    }
  }

  List<Expression> popListForValue(int n) {
    List<Expression> list =
        new List<Expression>.filled(n, dummyExpression, 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, dummyExpression, 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>()
                .popNonNullable(stack, count, dummyStatement) ??
            <Statement>[]);
  }

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

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

  Statement? popNullableStatement() {
    Statement? statement = pop(NullValues.Block) as Statement?;
    if (statement != null) {
      statement = forest.wrapVariables(statement);
    }
    return statement;
  }

  void enterSwitchScope() {
    _switchScopes.push(_labelScope);
  }

  void exitSwitchScope() {
    LabelScope switchScope = _switchScope!;
    LabelScope? outerSwitchScope =
        _switchScopes.hasPrevious ? _switchScopes.previous : null;
    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);
        }
      });
    }
    _switchScopes.pop();
  }

  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, LocalScope scope) {
    String name = variable.name!;
    Builder? existing = scope.lookupLocalVariable(name);
    if (existing != null) {
      // This reports an error for duplicated declarations in the same scope:
      // `{ var x; var x; }`
      wrapVariableInitializerInError(
          variable, fasta.templateDuplicatedDeclaration, <LocatedMessage>[
        fasta.templateDuplicatedDeclarationCause
            .withArguments(name)
            .withLocation(uri, existing.charOffset, name.length)
      ]);
      return;
    }
    if (isGuardScope(scope)) {
      (declaredInCurrentGuard ??= {}).add(variable);
    }
    String variableName = variable.name!;
    List<int>? previousOffsets =
        scope.declare(variableName, new VariableBuilderImpl(variable, uri));
    if (previousOffsets != null && previousOffsets.isNotEmpty) {
      // 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`.
      for (int previousOffset in previousOffsets) {
        addProblem(
            templateLocalVariableUsedBeforeDeclared.withArguments(variableName),
            previousOffset,
            variableName.length,
            context: <LocatedMessage>[
              templateLocalVariableUsedBeforeDeclaredContext
                  .withArguments(variableName)
                  .withLocation(uri, variable.fileOffset, variableName.length)
            ]);
      }
    }
  }

  JumpTarget createJumpTarget(JumpTargetKind kind, int charOffset) {
    return new JumpTarget(kind, functionNestingLevel, uri, charOffset);
  }

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

  @override
  void beginMetadata(Token token) {
    debugEvent("beginMetadata");
    super.push(constantContext);
    constantContext = ConstantContext.inferred;
    assert(checkState(token, [ValueKinds.ConstantContext]));
  }

  @override
  void endMetadata(Token beginToken, Token? periodBeforeName, Token endToken) {
    assert(checkState(beginToken, [
      /*arguments*/ ValueKinds.ArgumentsOrNull,
      /*suffix*/ if (periodBeforeName != null)
        unionOfKinds([ValueKinds.Identifier, ValueKinds.ParserRecovery]),
      /*type arguments*/ ValueKinds.TypeArgumentsOrNull,
      /*type*/ unionOfKinds([
        ValueKinds.Generator,
        ValueKinds.QualifiedName,
        ValueKinds.ProblemBuilder,
        ValueKinds.ParserRecovery
      ])
    ]));
    debugEvent("Metadata");
    Arguments? arguments = pop() as Arguments?;
    pushQualifiedReference(
        beginToken.next!, periodBeforeName, ConstructorReferenceContext.Const);
    assert(checkState(beginToken, [
      /*constructor name identifier*/ ValueKinds.IdentifierOrNull,
      /*constructor name*/ ValueKinds.Name,
      /*type arguments*/ ValueKinds.TypeArgumentsOrNull,
      /*class*/ unionOfKinds([
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
        ValueKinds.ParserRecovery
      ]),
    ]));
    if (arguments != null) {
      push(arguments);
      _buildConstructorReferenceInvocation(
          beginToken.next!, beginToken.offset, Constness.explicitConst,
          inMetadata: true, inImplicitCreationContext: false);
      push(popForValue());
    } else {
      pop(); // Name last identifier
      String? name = pop() as String?;
      pop(); // Type arguments (ignored, already reported by parser).
      Object? expression = pop();
      if (expression is Identifier) {
        // Coverage-ignore-block(suite): Not run.
        Identifier identifier = expression;
        expression = new UnresolvedNameGenerator(this, identifier.token,
            new Name(identifier.name, libraryBuilder.nameOrigin),
            unresolvedReadKind: UnresolvedKind.Unknown);
      }
      if (name?.isNotEmpty ?? false) {
        Token period = periodBeforeName ?? beginToken.next!.next!;
        Generator generator = expression as Generator;
        expression = generator.buildSelectorAccess(
            new PropertySelector(
                this, period.next!, new Name(name!, libraryBuilder.nameOrigin)),
            period.next!.offset,
            false);
      }

      ConstantContext savedConstantContext = pop() as ConstantContext;
      if (!(expression is StaticAccessGenerator &&
              expression.readTarget is Field) &&
          expression is! VariableUseGenerator &&
          // TODO(johnniwinther): Stop using the type of the generator here.
          // Ask a property instead.
          (expression is! ReadOnlyAccessGenerator ||
              // Coverage-ignore(suite): Not run.
              expression is TypeUseGenerator ||
              // Coverage-ignore(suite): Not run.
              expression is ParenthesizedExpressionGenerator)) {
        Expression value = toValue(expression);
        push(wrapInProblem(value, fasta.messageExpressionNotMetadata,
            value.fileOffset, noLength));
      } else {
        push(toValue(expression));
      }
      constantContext = savedConstantContext;
    }
    assert(checkState(beginToken, [ValueKinds.Expression]));
  }

  @override
  void endMetadataStar(int count) {
    assert(checkState(null, repeatedKind(ValueKinds.Expression, count)));
    debugEvent("MetadataStar");
    if (count == 0) {
      push(NullValues.Metadata);
    } else {
      push(const GrowableList<Expression>()
              .popNonNullable(stack, count, dummyExpression) ??
          NullValues.Metadata /* Ignore parser recovery */);
    }
    assert(checkState(null, [ValueKinds.AnnotationListOrNull]));
  }

  @override
  void endTopLevelFields(
      Token? augmentToken,
      Token? externalToken,
      Token? staticToken,
      Token? covariantToken,
      Token? lateToken,
      Token? varFinalOrConst,
      int count,
      Token beginToken,
      Token endToken) {
    debugEvent("TopLevelFields");
    push(count);
    assert(checkState(beginToken, [ValueKinds.Integer]));
  }

  @override
  void endClassFields(
      Token? abstractToken,
      Token? augmentToken,
      Token? externalToken,
      Token? staticToken,
      Token? covariantToken,
      Token? lateToken,
      Token? varFinalOrConst,
      int count,
      Token beginToken,
      Token endToken) {
    debugEvent("Fields");
    push(count);
    assert(checkState(beginToken, [ValueKinds.Integer]));
  }

  void finishFields() {
    debugEvent("finishFields");
    assert(checkState(null, [/*field count*/ ValueKinds.Integer]));
    int count = pop() as int;
    for (int i = 0; i < count; i++) {
      assert(checkState(null, [
        ValueKinds.FieldInitializerOrNull,
        ValueKinds.Identifier,
      ]));
      Expression? initializer = pop() as Expression?;
      Identifier identifier = pop() as Identifier;
      String name = identifier.name;
      Builder declaration = _context.lookupLocalMember(name, required: true)!;
      int fileOffset = identifier.nameOffset;
      while (declaration.next != null) {
        // If we have duplicates, we try to find the right declaration.
        if (declaration.fileUri == uri &&
            declaration.charOffset == fileOffset) {
          break;
        }
        declaration = declaration.next!;
      }
      if (declaration.fileUri != uri || declaration.charOffset != fileOffset) {
        // If we don't have the right declaration, skip the initializer.
        continue;
      }
      SourceFieldBuilder fieldBuilder;
      if (declaration.isField) {
        fieldBuilder = declaration as SourceFieldBuilder;
      } else {
        continue;
      }
      if (initializer != null) {
        if (!fieldBuilder.hasBodyBeenBuilt) {
          initializer = typeInferrer
              .inferFieldInitializer(this, fieldBuilder.builtType, initializer)
              .expression;
          fieldBuilder.buildBody(coreTypes, initializer);
        }
      } else if (!fieldBuilder.hasBodyBeenBuilt) {
        fieldBuilder.buildBody(coreTypes, null);
      }
    }
    assert(checkState(
        null, [ValueKinds.TypeOrNull, ValueKinds.AnnotationListOrNull]));
    {
      // 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`.
      TypeBuilder? type = pop() as TypeBuilder?;
      if (type != null) {
        buildDartType(type, TypeUse.fieldType,
            allowPotentiallyConstantType: false);
      }
    }
    pop(); // Annotations.

    performBacklogComputations();
    assert(stack.length == 0);
  }

  /// Perform delayed computations that were put on back log during body
  /// building.
  ///
  /// Back logged computations include resolution of redirecting factory
  /// invocations and checking of typedef types.
  void performBacklogComputations() {
    _finishVariableMetadata();
    libraryBuilder.checkPendingBoundsChecks(typeEnvironment);
  }

  void finishRedirectingFactoryBody() {
    performBacklogComputations();
  }

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

  @override
  void endBlockFunctionBody(int count, Token? openBrace, Token closeBrace) {
    debugEvent("BlockFunctionBody");
    if (openBrace == null) {
      assert(count == 0);
      push(NullValues.Block);
    } else {
      Statement block = popBlock(count, openBrace, closeBrace);
      exitLocalScope();
      push(block);
    }
    assert(checkState(closeBrace, [ValueKinds.StatementOrNull]));
  }

  void prepareInitializers() {
    _localScopes
        .push(_context.computeFormalParameterInitializerScope(_localScope));
    if (_context.isConstructor) {
      _context.prepareInitializers();
      if (_context.formals != null) {
        for (FormalParameterBuilder formal in _context.formals!) {
          if (formal.isInitializingFormal) {
            List<Initializer> initializers;
            if (_context.isExternalConstructor) {
              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) {
              _context.addInitializer(initializer, this, inferenceResult: null);
            }
          }
        }
      }
    }
  }

  @override
  void handleNoInitializers() {
    debugEvent("NoInitializers");
    if (functionNestingLevel == 0) {
      prepareInitializers();
      _localScopes.push(formalParameterScope ??
          new FixedLocalScope(
              kind: ScopeKind.initializers, debugName: "initializers"));
    }
  }

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

  @override
  void endInitializers(int count, Token beginToken, Token endToken) {
    debugEvent("Initializers");
    if (functionNestingLevel == 0) {
      _localScopes.push(formalParameterScope ??
          new FixedLocalScope(
              kind: ScopeKind.initializers, debugName: "initializers"));
    }
    inConstructorInitializer = false;
  }

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

  @override
  void endInitializer(Token endToken) {
    assert(checkState(endToken, [
      unionOfKinds([
        ValueKinds.Initializer,
        ValueKinds.Generator,
        ValueKinds.Expression,
      ])
    ]));

    debugEvent("endInitializer");
    inFieldInitializer = false;
    assert(!inInitializerLeftHandSide);
    Object? node = pop();
    List<Initializer> initializers;

    if (!(_context.isConstructor && !_context.isExternalConstructor)) {
      // 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) {
      // Coverage-ignore-block(suite): Not run.
      initializers = <Initializer>[
        // TODO(jensj): Does this offset make sense?
        buildSuperInitializer(
            false, node.target, node.arguments, endToken.next!.charOffset)
      ];
    } else {
      Expression value = toValue(node);
      if (!forest.isThrow(node)) {
        value = wrapInProblem(value, fasta.messageExpectedAnInitializer,
            value.fileOffset, noLength);
      }
      initializers = <Initializer>[
        // TODO(johnniwinther): This should probably be [value] instead of
        //  [node].
        // TODO(jensj): Does this offset make sense?
        buildInvalidInitializer(node as Expression, endToken.next!.charOffset)
      ];
    }

    _initializers ??= <Initializer>[];
    _initializers!.addAll(initializers);
  }

  List<Object>? createSuperParametersAsArguments(
      List<FormalParameterBuilder> formals) {
    List<Object>? superParametersAsArguments;
    for (FormalParameterBuilder formal in formals) {
      if (formal.isSuperInitializingFormal) {
        if (formal.isNamed) {
          (superParametersAsArguments ??= <Object>[]).add(new NamedExpression(
              formal.name,
              createVariableGet(formal.variable!, formal.charOffset,
                  forNullGuardedAccess: false))
            ..fileOffset = formal.charOffset);
        } else {
          (superParametersAsArguments ??= <Object>[]).add(createVariableGet(
              formal.variable!, formal.charOffset,
              forNullGuardedAccess: false));
        }
      }
    }
    return superParametersAsArguments;
  }

  void finishFunction(
      FormalParameters? formals, AsyncMarker asyncModifier, Statement? body) {
    debugEvent("finishFunction");

    // Create variable get expressions for super parameters before finishing
    // the analysis of the assigned variables. Creating the expressions later
    // that point results in a flow analysis error.
    List<Object>? superParametersAsArguments;
    if (formals != null) {
      List<FormalParameterBuilder>? formalParameters = formals.parameters;
      if (formalParameters != null) {
        superParametersAsArguments =
            createSuperParametersAsArguments(formalParameters);
      }
    }
    typeInferrer.assignedVariables.finish();

    FunctionNode function = _context.function;
    if (thisVariable != null) {
      typeInferrer.flowAnalysis
          .declare(thisVariable!, thisVariable!.type, initialized: true);
    }
    if (formals?.parameters != null) {
      for (int i = 0; i < formals!.parameters!.length; i++) {
        FormalParameterBuilder parameter = formals.parameters![i];
        VariableDeclaration variable = parameter.variable!;
        typeInferrer.flowAnalysis
            .declare(variable, variable.type, initialized: true);
      }
      for (int i = 0; i < formals.parameters!.length; i++) {
        FormalParameterBuilder parameter = formals.parameters![i];
        Expression? initializer = parameter.variable!.initializer;
        bool inferInitializer;
        if (parameter.isSuperInitializingFormal) {
          // Super-parameters can inherit the default value from the super
          // constructor so we only handle explicit default values here.
          inferInitializer = parameter.hasImmediatelyDeclaredInitializer;
        } else if (initializer != null) {
          inferInitializer = true;
        } else {
          inferInitializer = parameter.isOptional;
        }
        if (inferInitializer) {
          if (!parameter.initializerWasInferred) {
            // Coverage-ignore(suite): Not run.
            initializer ??= forest.createNullLiteral(
                // TODO(ahe): Should store: originParameter.fileOffset
                // https://github.com/dart-lang/sdk/issues/32289
                noLocation);
            VariableDeclaration originParameter =
                _context.getFormalParameter(i);
            initializer = typeInferrer.inferParameterInitializer(
                this,
                initializer,
                originParameter.type,
                parameter.hasDeclaredInitializer);
            originParameter.initializer = initializer..parent = originParameter;
            parameter.initializerWasInferred = true;
          }
          VariableDeclaration? tearOffParameter =
              _context.getTearOffParameter(i);
          if (tearOffParameter != null) {
            Expression tearOffInitializer =
                _cloner.cloneInContext(initializer!);
            tearOffParameter.initializer = tearOffInitializer
              ..parent = tearOffParameter;
          }
        }
      }
    }

    if (_context.isConstructor) {
      finishConstructor(asyncModifier, body,
          superParametersAsArguments: superParametersAsArguments);
    } else if (body != null) {
      _context.setAsyncModifier(asyncModifier);
    }

    InferredFunctionBody? inferredFunctionBody;
    if (body != null) {
      inferredFunctionBody = typeInferrer.inferFunctionBody(
          this,
          _context.memberCharOffset,
          _context.returnTypeContext,
          asyncModifier,
          body);
      body = inferredFunctionBody.body;
      function.emittedValueType = inferredFunctionBody.emittedValueType;
      assert(function.asyncMarker == AsyncMarker.Sync ||
          function.emittedValueType != null);
    }

    if (_context.returnType is! OmittedTypeBuilder) {
      checkAsyncReturnType(asyncModifier, function.returnType,
          _context.memberCharOffset, _context.memberName.length);
    }

    if (_context.isSetter) {
      if (formals?.parameters == null ||
          formals!.parameters!.length != 1 ||
          formals.parameters!.single.isOptionalPositional) {
        int charOffset = formals?.charOffset ??
            // Coverage-ignore(suite): Not run.
            body?.fileOffset ??
            // Coverage-ignore(suite): Not run.
            _context.memberCharOffset;
        if (body == null) {
          body = new EmptyStatement()..fileOffset = charOffset;
        }
        if (_context.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 _context.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 = (function.parent is Procedure &&
        (function.parent as Procedure).isNoSuchMethodForwarder);
    if (body != null) {
      if (_context.isExternalFunction || isNoSuchMethodForwarder) {
        body = new Block(<Statement>[
          new ExpressionStatement(buildProblem(
              fasta.messageExternalMethodWithBody, body.fileOffset, noLength))
            ..fileOffset = body.fileOffset,
          body,
        ])
          ..fileOffset = body.fileOffset;
      }
      _context.setBody(body);
    }

    performBacklogComputations();
  }

  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
    }

    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
            .lookupLoadedLibraryBuilder(ensureLibraryLoaded.importUri) ??
        // Coverage-ignore(suite): Not run.
        libraryBuilder.loader.target.dillTarget.loader
            .lookupLibraryBuilder(ensureLibraryLoaded.importUri);
    if (builder is DillLibraryBuilder) {
      builder.ensureLoaded();
    }
  }

  RedirectionTarget _getRedirectionTarget(Procedure factory) {
    List<DartType> typeArguments = new List<DartType>.generate(
        factory.function.typeParameters.length, (int i) {
      return new TypeParameterType.withDefaultNullabilityForLibrary(
          factory.function.typeParameters[i], factory.enclosingLibrary);
    }, growable: true);

    // Cyclic factories are detected earlier, so we're guaranteed to
    // reach either a non-redirecting factory or an error eventually.
    Member target = factory;
    for (;;) {
      RedirectingFactoryTarget? redirectingFactoryTarget =
          target.function?.redirectingFactoryTarget;
      if (redirectingFactoryTarget == null ||
          redirectingFactoryTarget.isError) {
        return new RedirectionTarget(target, typeArguments);
      }
      Member nextMember = redirectingFactoryTarget.target!;
      ensureLoaded(nextMember);
      List<DartType>? nextTypeArguments =
          redirectingFactoryTarget.typeArguments;
      if (nextTypeArguments != null) {
        Substitution sub = Substitution.fromPairs(
            target.function!.typeParameters, typeArguments);
        typeArguments =
            new List<DartType>.generate(nextTypeArguments.length, (int i) {
          return sub.substituteType(nextTypeArguments[i]);
        }, growable: true);
      } else {
        // Coverage-ignore-block(suite): Not run.
        typeArguments = <DartType>[];
      }
      target = nextMember;
    }
  }

  /// 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.
  @override
  Expression? resolveRedirectingFactoryTarget(
      Procedure target, Arguments arguments, int fileOffset, bool isConst) {
    Procedure initialTarget = target;
    Expression replacementNode;

    RedirectionTarget redirectionTarget = _getRedirectionTarget(initialTarget);
    Member resolvedTarget = redirectionTarget.target;
    if (redirectionTarget.typeArguments.any((type) => type is UnknownType)) {
      return null;
    }

    RedirectingFactoryTarget? redirectingFactoryTarget =
        resolvedTarget.function?.redirectingFactoryTarget;
    if (redirectingFactoryTarget != null) {
      // If the redirection target is itself a redirecting factory, it means
      // that it is unresolved.
      assert(redirectingFactoryTarget.isError);
      String errorMessage = redirectingFactoryTarget.errorMessage!;
      replacementNode = new InvalidExpression(errorMessage)
        ..fileOffset = fileOffset;
    } else {
      Substitution substitution = Substitution.fromPairs(
          initialTarget.function.typeParameters, arguments.types);
      for (int i = 0; i < redirectionTarget.typeArguments.length; i++) {
        DartType typeArgument =
            substitution.substituteType(redirectionTarget.typeArguments[i]);
        if (i < arguments.types.length) {
          arguments.types[i] = typeArgument;
        } else {
          arguments.types.add(typeArgument);
        }
      }
      arguments.types.length = redirectionTarget.typeArguments.length;

      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,
          isConstructorInvocation: true);
    }
    return replacementNode;
  }

  @override
  Expression unaliasSingleTypeAliasedConstructorInvocation(
      TypeAliasedConstructorInvocation invocation) {
    bool inferred = !hasExplicitTypeArguments(invocation.arguments);
    DartType aliasedType = new TypedefType(invocation.typeAliasBuilder.typedef,
        Nullability.nonNullable, invocation.arguments.types);
    libraryBuilder.checkBoundsInType(
        aliasedType, typeEnvironment, uri, invocation.fileOffset,
        allowSuperBounded: false, inferred: inferred);
    DartType unaliasedType = aliasedType.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);
    return new ConstructorInvocation(invocation.target, invocationArguments,
        isConst: invocation.isConst);
  }

  @override
  Expression? unaliasSingleTypeAliasedFactoryInvocation(
      TypeAliasedFactoryInvocation invocation) {
    bool inferred = !hasExplicitTypeArguments(invocation.arguments);
    DartType aliasedType = new TypedefType(invocation.typeAliasBuilder.typedef,
        Nullability.nonNullable, invocation.arguments.types);
    libraryBuilder.checkBoundsInType(
        aliasedType, typeEnvironment, uri, invocation.fileOffset,
        allowSuperBounded: false, inferred: inferred);
    DartType unaliasedType = aliasedType.unalias;
    List<DartType>? invocationTypeArguments = null;
    if (unaliasedType is TypeDeclarationType) {
      invocationTypeArguments = unaliasedType.typeArguments;
    }
    Arguments invocationArguments = forest.createArguments(
        noLocation, invocation.arguments.positional,
        types: invocationTypeArguments,
        named: invocation.arguments.named,
        hasExplicitTypeArguments:
            hasExplicitTypeArguments(invocation.arguments));
    return resolveRedirectingFactoryTarget(invocation.target,
        invocationArguments, invocation.fileOffset, invocation.isConst);
  }

  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++) {
          VariableDeclaration variable = variables[i];
          for (int i = 0; i < annotations.length; i++) {
            variable.addAnnotation(_cloner.cloneInContext(annotations[i]));
          }
        }
      }
    }
  }

  List<Expression> finishMetadata(Annotatable? parent) {
    assert(checkState(null, [ValueKinds.AnnotationList]));
    List<Expression> expressions = pop() as List<Expression>;
    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 != null) {
      for (Expression expression in expressions) {
        parent.addAnnotation(expression);
      }
    } else {
      // Coverage-ignore-block(suite): Not run.
      temporaryParent = new ListLiteral(expressions);
    }
    performBacklogComputations();
    // Coverage-ignore(suite): Not run.
    return temporaryParent != null ? temporaryParent.expressions : expressions;
  }

  // Coverage-ignore(suite): Not run.
  Expression parseSingleExpression(
      Parser parser, Token token, FunctionNode parameters) {
    int fileOffset = offsetForToken(token);
    List<NominalVariableBuilder>? typeParameterBuilders;
    for (TypeParameter typeParameter in parameters.typeParameters) {
      typeParameterBuilders ??= <NominalVariableBuilder>[];
      typeParameterBuilders.add(new NominalVariableBuilder.fromKernel(
          typeParameter,
          loader: libraryBuilder.loader));
    }
    enterNominalVariablesScope(typeParameterBuilders);

    List<FormalParameterBuilder>? formals =
        parameters.positionalParameters.length == 0
            ? null
            : new List<FormalParameterBuilder>.generate(
                parameters.positionalParameters.length, (int i) {
                VariableDeclaration formal = parameters.positionalParameters[i];
                String formalName = formal.name!;
                bool isWildcard = libraryFeatures.wildcardVariables.isEnabled &&
                    formalName == '_';
                if (isWildcard) {
                  formalName =
                      createWildcardFormalParameterName(wildcardVariableIndex);
                  wildcardVariableIndex++;
                }
                return new FormalParameterBuilder(
                    FormalParameterKind.requiredPositional,
                    /* modifiers = */ 0,
                    const ImplicitTypeBuilder(),
                    formalName,
                    libraryBuilder,
                    formal.fileOffset,
                    fileUri: uri,
                    hasImmediatelyDeclaredInitializer: false,
                    isWildcard: isWildcard)
                  ..variable = formal;
              }, growable: false);
    enterLocalScope(new FormalParameters(formals, fileOffset, noLength, uri)
        .computeFormalParameterScope(
      _localScope,
      this,
      wildcardVariablesEnabled: libraryFeatures.wildcardVariables.isEnabled,
    ));

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

    assert(checkState(token, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
      ])
    ]));
    Expression expression = popForValue();
    Token eof = endToken.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++) {
        VariableDeclaration variable = formals[i].variable!;
        typeInferrer.flowAnalysis
            .declare(variable, variable.type, initialized: 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.");

    performBacklogComputations();

    return fakeReturn.expression!;
  }

  List<Initializer>? parseInitializers(Token token,
      {bool doFinishConstructor = true}) {
    Parser parser = new Parser(this,
        useImplicitCreationExpression: useImplicitCreationExpressionInCfe,
        allowPatterns: libraryFeatures.patterns.isEnabled);
    if (!token.isEof) {
      token = parser.parseInitializers(token);
      checkEmpty(token.charOffset);
    } else {
      handleNoInitializers();
    }
    if (doFinishConstructor) {
      List<FormalParameterBuilder>? formals = _context.formals;
      finishConstructor(AsyncMarker.Sync, null,
          superParametersAsArguments: formals != null
              ? createSuperParametersAsArguments(formals)
              : null);
    }
    return _initializers;
  }

  Expression parseFieldInitializer(Token token) {
    Parser parser = new Parser(this,
        useImplicitCreationExpression: useImplicitCreationExpressionInCfe,
        allowPatterns: libraryFeatures.patterns.isEnabled);
    Token endToken =
        parser.parseExpression(parser.syntheticPreviousToken(token));
    assert(checkState(token, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
      ])
    ]));
    Expression expression = popForValue();
    checkEmpty(endToken.charOffset);
    return expression;
  }

  Expression parseAnnotation(Token token) {
    Parser parser = new Parser(this,
        useImplicitCreationExpression: useImplicitCreationExpressionInCfe,
        allowPatterns: libraryFeatures.patterns.isEnabled);
    Token endToken = parser.parseMetadata(parser.syntheticPreviousToken(token));
    assert(checkState(token, [ValueKinds.Expression]));
    Expression annotation = pop() as Expression;
    checkEmpty(endToken.charOffset);
    return annotation;
  }

  ArgumentsImpl parseArguments(Token token) {
    Parser parser = new Parser(this,
        useImplicitCreationExpression: useImplicitCreationExpressionInCfe,
        allowPatterns: libraryFeatures.patterns.isEnabled);
    token = parser.parseArgumentsRest(token);
    ArgumentsImpl arguments = pop() as ArgumentsImpl;
    checkEmpty(token.charOffset);
    return arguments;
  }

  void finishConstructor(AsyncMarker asyncModifier, Statement? body,
      {required List<Object /* Expression | NamedExpression */ >?
          superParametersAsArguments}) {
    /// Quotes below are from [Dart Programming Language Specification, 4th
    /// Edition](
    /// https://ecma-international.org/publications/files/ECMA-ST/ECMA-408.pdf).
    assert(() {
      if (superParametersAsArguments == null) {
        return true;
      }
      for (Object superParameterAsArgument in superParametersAsArguments) {
        if (superParameterAsArgument is! Expression &&
            superParameterAsArgument is! NamedExpression) {
          return false;
        }
      }
      return true;
    }(),
        "Expected 'superParametersAsArguments' "
        "to contain nothing but Expressions and NamedExpressions.");
    assert(() {
      if (superParametersAsArguments == null) {
        return true;
      }
      int previousOffset = -1;
      for (Object superParameterAsArgument in superParametersAsArguments) {
        int offset;
        if (superParameterAsArgument is Expression) {
          offset = superParameterAsArgument.fileOffset;
        } else if (superParameterAsArgument is NamedExpression) {
          offset = superParameterAsArgument.value.fileOffset;
        } else {
          return false;
        }
        if (previousOffset > offset) {
          return false;
        }
        previousOffset = offset;
      }
      return true;
    }(),
        "Expected 'superParametersAsArguments' "
        "to be sorted by occurrence in file.");

    FunctionNode function = _context.function;
    List<FormalParameterBuilder>? formals = _context.formals;
    if (formals != null) {
      for (int i = 0; i < formals.length; i++) {
        FormalParameterBuilder parameter = formals[i];
        VariableDeclaration variable = parameter.variable!;
        // TODO(paulberry): `skipDuplicateCheck` is currently needed to work
        // around a failure in
        // co19/Language/Expressions/Postfix_Expressions/conditional_increment_t02;
        // fix this.
        typeInferrer.flowAnalysis.declare(variable, variable.type,
            initialized: true, skipDuplicateCheck: true);
      }
    }

    Set<String>? namedSuperParameterNames;
    List<Expression>? positionalSuperParametersAsArguments;
    List<NamedExpression>? namedSuperParametersAsArguments;
    if (superParametersAsArguments != null) {
      for (Object superParameterAsArgument in superParametersAsArguments) {
        if (superParameterAsArgument is Expression) {
          (positionalSuperParametersAsArguments ??= <Expression>[])
              .add(superParameterAsArgument);
        } else {
          NamedExpression namedSuperParameterAsArgument =
              superParameterAsArgument as NamedExpression;
          (namedSuperParametersAsArguments ??= <NamedExpression>[])
              .add(namedSuperParameterAsArgument);
          (namedSuperParameterNames ??= <String>{})
              .add(namedSuperParameterAsArgument.name);
        }
      }
    } else if (formals != null) {
      for (FormalParameterBuilder formal in formals) {
        if (formal.isSuperInitializingFormal) {
          // Coverage-ignore-block(suite): Not run.
          if (formal.isNamed) {
            NamedExpression superParameterAsArgument = new NamedExpression(
                formal.name,
                createVariableGet(formal.variable!, formal.charOffset,
                    forNullGuardedAccess: false))
              ..fileOffset = formal.charOffset;
            (namedSuperParametersAsArguments ??= <NamedExpression>[])
                .add(superParameterAsArgument);
            (namedSuperParameterNames ??= <String>{}).add(formal.name);
            (superParametersAsArguments ??= <Object>[])
                .add(superParameterAsArgument);
          } else {
            Expression superParameterAsArgument = createVariableGet(
                formal.variable!, formal.charOffset,
                forNullGuardedAccess: false);
            (positionalSuperParametersAsArguments ??= <Expression>[])
                .add(superParameterAsArgument);
            (superParametersAsArguments ??= <Object>[])
                .add(superParameterAsArgument);
          }
        }
      }
    }

    List<Initializer>? initializers = _initializers;
    if (initializers != null && initializers.isNotEmpty) {
      if (_context.isMixinClass) {
        // Report an error if a mixin class has a constructor with an
        // initializer.
        buildProblem(
            fasta.templateIllegalMixinDueToConstructors
                .withArguments(_context.className),
            _context.memberCharOffset,
            noLength);
      }
      if (initializers.last is SuperInitializer) {
        SuperInitializer superInitializer =
            initializers.last as SuperInitializer;
        if (_context.isEnumClass) {
          initializers[initializers.length - 1] = buildInvalidInitializer(
              buildProblem(fasta.messageEnumConstructorSuperInitializer,
                  superInitializer.fileOffset, noLength))
            ..parent = superInitializer.parent;
        } else if (libraryFeatures.superParameters.isEnabled) {
          ArgumentsImpl arguments = superInitializer.arguments as ArgumentsImpl;

          if (positionalSuperParametersAsArguments != null) {
            if (arguments.positional.isNotEmpty) {
              addProblem(fasta.messagePositionalSuperParametersAndArguments,
                  arguments.fileOffset, noLength,
                  context: <LocatedMessage>[
                    fasta.messageSuperInitializerParameter.withLocation(
                        uri,
                        (positionalSuperParametersAsArguments.first
                                as VariableGet)
                            .variable
                            .fileOffset,
                        noLength)
                  ]);
            } else {
              arguments.positional.addAll(positionalSuperParametersAsArguments);
              setParents(positionalSuperParametersAsArguments, arguments);
              arguments.positionalAreSuperParameters = true;
            }
          }
          if (namedSuperParametersAsArguments != null) {
            // TODO(cstefantsova): Report name conflicts.
            arguments.named.addAll(namedSuperParametersAsArguments);
            setParents(namedSuperParametersAsArguments, arguments);
            arguments.namedSuperParameterNames = namedSuperParameterNames;
          }
          if (superParametersAsArguments != null) {
            arguments.argumentsOriginalOrder
                ?.insertAll(0, superParametersAsArguments);
          }
        }
      } else if (initializers.last is RedirectingInitializer) {
        RedirectingInitializer redirectingInitializer =
            initializers.last as RedirectingInitializer;
        if (_context.isEnumClass && libraryFeatures.enhancedEnums.isEnabled) {
          ArgumentsImpl arguments =
              redirectingInitializer.arguments as ArgumentsImpl;
          List<Expression> enumSyntheticArguments = [
            new VariableGetImpl(function.positionalParameters[0],
                forNullGuardedAccess: false)
              ..parent = redirectingInitializer.arguments,
            new VariableGetImpl(function.positionalParameters[1],
                forNullGuardedAccess: false)
              ..parent = redirectingInitializer.arguments
          ];
          arguments.positional.insertAll(0, enumSyntheticArguments);
          arguments.argumentsOriginalOrder
              ?.insertAll(0, enumSyntheticArguments);
        }
      }

      List<InitializerInferenceResult> inferenceResults =
          new List<InitializerInferenceResult>.generate(
              initializers.length,
              (index) => _context.inferInitializer(
                  initializers[index], this, typeInferrer),
              growable: false);

      if (!_context.isExternalConstructor) {
        for (int i = 0; i < initializers.length; i++) {
          _context.addInitializer(initializers[i], this,
              inferenceResult: inferenceResults[i]);
        }
      }
    }

    if (asyncModifier != AsyncMarker.Sync) {
      _context.addInitializer(
          buildInvalidInitializer(buildProblem(
              fasta.messageConstructorNotSync, body!.fileOffset, noLength)),
          this,
          inferenceResult: null);
    }
    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 = lookupSuperConstructor(emptyName);
      Initializer initializer;
      ArgumentsImpl arguments;
      List<Expression>? positionalArguments;
      List<NamedExpression>? namedArguments;
      if (libraryFeatures.superParameters.isEnabled) {
        positionalArguments = positionalSuperParametersAsArguments;
        namedArguments = namedSuperParametersAsArguments;
      }
      if (_context.isEnumClass) {
        assert(function.positionalParameters.length >= 2 &&
            function.positionalParameters[0].name == "#index" &&
            function.positionalParameters[1].name == "#name");
        (positionalArguments ??= <Expression>[]).insertAll(0, [
          new VariableGetImpl(function.positionalParameters[0],
              forNullGuardedAccess: false),
          new VariableGetImpl(function.positionalParameters[1],
              forNullGuardedAccess: false)
        ]);
      }

      if (positionalArguments != null || namedArguments != null) {
        arguments = forest.createArguments(
            noLocation, positionalArguments ?? <Expression>[],
            named: namedArguments);
      } else {
        arguments = forest.createArgumentsEmpty(noLocation);
      }

      arguments.positionalAreSuperParameters =
          positionalSuperParametersAsArguments != null;
      arguments.namedSuperParameterNames = namedSuperParameterNames;

      if (superTarget == null ||
          checkArgumentsForFunction(superTarget.function, arguments,
                  _context.memberCharOffset, const <TypeParameter>[]) !=
              null) {
        String superclass = _context.superClassName;
        int length = _context.memberName.length;
        if (length == 0) {
          length = _context.className.length;
        }
        initializer = buildInvalidInitializer(
            buildProblem(
                fasta.templateSuperclassHasNoDefaultConstructor
                    .withArguments(superclass),
                _context.memberCharOffset,
                length),
            _context.memberCharOffset);
      } else {
        initializer = buildSuperInitializer(
            true, superTarget, arguments, _context.memberCharOffset);
      }
      if (libraryFeatures.superParameters.isEnabled) {
        InitializerInferenceResult inferenceResult =
            _context.inferInitializer(initializer, this, typeInferrer);
        _context.addInitializer(initializer, this,
            inferenceResult: inferenceResult);
      } else {
        _context.addInitializer(initializer, this, inferenceResult: null);
      }
    }
    if (body == null && !_context.isExternalConstructor) {
      /// >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.
      function.body = new EmptyStatement()..parent = function;
    } else if (body != null && _context.isMixinClass && !_context.isFactory) {
      // Report an error if a mixin class has a non-factory constructor with a
      // body.
      buildProblem(
          fasta.templateIllegalMixinDueToConstructors
              .withArguments(_context.className),
          _context.memberCharOffset,
          noLength);
    }
  }

  @override
  void handleExpressionStatement(Token beginToken, Token endToken) {
    assert(checkState(endToken, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
      ]),
    ]));
    debugEvent("ExpressionStatement");
    push(forest.createExpressionStatement(
        offsetForToken(endToken), 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;
    }
    List<Object?>? argumentsOriginalOrder;
    if (libraryFeatures.namedArgumentsAnywhere.isEnabled) {
      argumentsOriginalOrder = new List<Object?>.of(arguments);
    }
    int firstNamedArgumentIndex = arguments.length;
    int positionalCount = 0;
    bool hasNamedBeforePositional = false;
    for (int i = 0; i < arguments.length; i++) {
      Object? node = arguments[i];
      if (node is NamedExpression) {
        firstNamedArgumentIndex =
            i < firstNamedArgumentIndex ? i : firstNamedArgumentIndex;
      } else {
        positionalCount++;
        Expression argument = toValue(node);
        arguments[i] = argument;
        argumentsOriginalOrder?[i] = argument;
        if (i > firstNamedArgumentIndex) {
          hasNamedBeforePositional = true;
          if (!libraryFeatures.namedArgumentsAnywhere.isEnabled) {
            arguments[i] = new NamedExpression(
                "#$i",
                buildProblem(fasta.messageExpectedNamedArgument,
                    argument.fileOffset, noLength))
              ..fileOffset = beginToken.charOffset;
          }
        }
      }
    }
    if (!hasNamedBeforePositional) {
      argumentsOriginalOrder = null;
    }
    if (firstNamedArgumentIndex < arguments.length) {
      List<Expression> positional;
      List<NamedExpression> named;
      if (libraryFeatures.namedArgumentsAnywhere.isEnabled) {
        positional = new List<Expression>.filled(
            positionalCount, dummyExpression,
            growable: true);
        named = new List<NamedExpression>.filled(
            arguments.length - positionalCount, dummyNamedExpression,
            growable: true);
        int positionalIndex = 0;
        int namedIndex = 0;
        for (int i = 0; i < arguments.length; i++) {
          if (arguments[i] is NamedExpression) {
            named[namedIndex++] = arguments[i] as NamedExpression;
          } else {
            positional[positionalIndex++] = arguments[i] as Expression;
          }
        }
        assert(
            positionalIndex == positional.length && namedIndex == named.length);
      } else {
        // arguments have non-null Expression entries after the initial loop.
        positional = new List<Expression>.from(
            arguments.getRange(0, firstNamedArgumentIndex));
        named = new List<NamedExpression>.from(
            arguments.getRange(firstNamedArgumentIndex, arguments.length));
      }

      push(forest.createArguments(beginToken.offset, positional,
          named: named, argumentsOriginalOrder: argumentsOriginalOrder));
    } 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.

      // arguments have non-null Expression entries after the initial loop.
      push(forest.createArguments(
          beginToken.offset, new List<Expression>.from(arguments),
          argumentsOriginalOrder: argumentsOriginalOrder));
    }
    assert(checkState(beginToken, [ValueKinds.Arguments]));
  }

  @override
  void handleParenthesizedCondition(Token token, Token? case_, Token? when) {
    debugEvent("ParenthesizedCondition");
    if (case_ != null) {
      Expression? guard;
      if (when != null) {
        assert(checkState(token, [
          unionOfKinds([
            ValueKinds.Expression,
            ValueKinds.Generator,
            ValueKinds.ProblemBuilder,
          ]),
          unionOfKinds([
            ValueKinds.Expression,
            ValueKinds.Pattern,
          ]),
          unionOfKinds([
            ValueKinds.Expression,
            ValueKinds.Generator,
            ValueKinds.ProblemBuilder,
          ]),
        ]));
        guard = popForValue();
      }
      assert(checkState(token, [
        unionOfKinds([
          ValueKinds.Expression,
          ValueKinds.Pattern,
        ]),
        unionOfKinds([
          ValueKinds.Expression,
          ValueKinds.Generator,
          ValueKinds.ProblemBuilder,
        ]),
      ]));
      reportIfNotEnabled(
          libraryFeatures.patterns, case_.charOffset, case_.charCount);
      Pattern pattern = toPattern(pop());
      Expression expression = popForValue();
      push(new Condition(expression,
          forest.createPatternGuard(expression.fileOffset, pattern, guard)));
    } else {
      assert(checkState(token, [
        unionOfKinds([
          ValueKinds.Expression,
          ValueKinds.Generator,
          ValueKinds.ProblemBuilder,
        ]),
      ]));
      push(new Condition(popForValue()));
    }
    assert(checkState(token, [
      ValueKinds.Condition,
    ]));
  }

  @override
  void endParenthesizedExpression(Token token) {
    assert(checkState(token, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
      ]),
    ]));
    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));
    }
    assert(checkState(token, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
      ]),
    ]));
  }

  @override
  void handleParenthesizedPattern(Token token) {
    debugEvent("ParenthesizedPattern");
    assert(checkState(token, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
        ValueKinds.Pattern,
      ])
    ]));
    // TODO(johnniwinther): Do we need a ParenthesizedPattern ?
    reportIfNotEnabled(
        libraryFeatures.patterns, token.charOffset, token.charCount);

    Object? value = pop();
    if (value is Pattern) {
      push(value);
    } else {
      push(toValue(value));
    }
  }

  @override
  void handleSend(Token beginToken, Token endToken) {
    assert(checkState(beginToken, [
      unionOfKinds([
        ValueKinds.ArgumentsOrNull,
        ValueKinds.ParserRecovery,
      ]),
      ValueKinds.TypeArgumentsOrNull,
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.Identifier,
        ValueKinds.ParserRecovery,
        ValueKinds.ProblemBuilder
      ])
    ]));
    debugEvent("Send");
    Object? arguments = pop();
    List<TypeBuilder>? typeArguments = pop() as List<TypeBuilder>?;
    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 is Arguments &&
        typeArguments != null &&
        (receiver is! TypeUseGenerator ||
            receiver.declaration is! TypeAliasBuilder);
    if (isInForest) {
      assert(forest.argumentsTypeArguments(arguments).isEmpty);
      forest.argumentsSetTypeArguments(
          arguments,
          buildDartTypeArguments(typeArguments, TypeUse.invocationTypeArgument,
              allowPotentiallyConstantType: false));
    } else {
      assert(typeArguments == null ||
          (receiver is TypeUseGenerator &&
              receiver.declaration is TypeAliasBuilder));
    }
    if (receiver is ParserRecovery || arguments is ParserRecovery) {
      push(new ParserErrorGenerator(
          this, beginToken, fasta.messageSyntheticToken));
    } else if (receiver is Identifier) {
      Name name = new Name(receiver.name, libraryBuilder.nameOrigin);
      if (arguments == null) {
        push(new PropertySelector(this, beginToken, name));
      } else {
        push(new InvocationSelector(
            this, beginToken, name, typeArguments, arguments as Arguments,
            isTypeArgumentsInForest: isInForest));
      }
    } else if (arguments == null) {
      push(receiver);
    } else {
      push(finishSend(receiver, typeArguments, arguments as ArgumentsImpl,
          beginToken.charOffset,
          isTypeArgumentsInForest: isInForest));
    }
    assert(checkState(beginToken, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.Initializer,
        ValueKinds.ProblemBuilder,
        ValueKinds.Selector,
      ])
    ]));
  }

  @override
  Expression_Generator_Initializer finishSend(Object receiver,
      List<TypeBuilder>? typeArguments, ArgumentsImpl 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) {
    assert(checkState(token, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
      ]),
    ]));
    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);
      VariableDeclaration variable =
          createVariableDeclarationForValue(expression);
      push(new Cascade(variable, isNullAware: isNullAware)
        ..fileOffset = expression.fileOffset);
      push(_createReadOnlyVariableAccess(variable, token, expression.fileOffset,
          null, ReadOnlyAccessKind.LetVariable));
    }
    assert(checkState(token, [
      ValueKinds.Generator,
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
      ]),
    ]));
  }

  @override
  void endCascade() {
    assert(checkState(null, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
      ]),
      ValueKinds.Expression,
    ]));
    debugEvent("endCascade");
    Expression expression = popForEffect();
    Cascade cascadeReceiver = pop() as Cascade;
    cascadeReceiver.addCascadeExpression(expression);
    push(cascadeReceiver);
  }

  @override
  void beginCaseExpression(Token caseKeyword) {
    debugEvent("beginCaseExpression");

    // Scope of the preceding case head or a sentinel if it's the first head.
    exitLocalScope(expectedScopeKinds: const [ScopeKind.caseHead]);

    createAndEnterLocalScope(debugName: "case-head", kind: ScopeKind.caseHead);
    super.push(constantContext);
    if (!libraryFeatures.patterns.isEnabled) {
      constantContext = ConstantContext.inferred;
    }
    assert(checkState(caseKeyword, [ValueKinds.ConstantContext]));
  }

  @override
  void endCaseExpression(Token caseKeyword, Token? when, Token colon) {
    debugEvent("endCaseExpression");
    assert(checkState(colon, [
      if (when != null)
        unionOfKinds([
          ValueKinds.Expression,
          ValueKinds.Generator,
          ValueKinds.ProblemBuilder,
        ]),
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
        ValueKinds.Pattern,
      ]),
      ValueKinds.ConstantContext,
    ]));

    Expression? guard;
    if (when != null) {
      guard = popForValue();
    }
    Object? value = pop();
    constantContext = pop() as ConstantContext;
    assert(
        _localScopes.previous.kind == ScopeKind.switchBlock,
        // Coverage-ignore(suite): Not run.
        "Expected to have scope kind ${ScopeKind.switchBlock}, "
        "but got ${_localScopes.previous.kind}.");
    if (value is Pattern) {
      super.push(new ExpressionOrPatternGuardCase.patternGuard(
          caseKeyword.charOffset,
          forest.createPatternGuard(caseKeyword.charOffset, value, guard)));
    } else if (guard != null) {
      super.push(new ExpressionOrPatternGuardCase.patternGuard(
          caseKeyword.charOffset,
          forest.createPatternGuard(
              caseKeyword.charOffset, toPattern(value), guard)));
    } else {
      Expression expression = toValue(value);
      super.push(new ExpressionOrPatternGuardCase.expression(
          caseKeyword.charOffset, expression));
    }
    assert(checkState(colon, [ValueKinds.ExpressionOrPatternGuardCase]));
  }

  @override
  void beginBinaryExpression(Token token) {
    assert(checkState(token, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
      ]),
    ]));
    bool isAnd = optional("&&", token);
    if (isAnd || optional("||", token)) {
      Expression lhs = popForValue();
      // This is matched by the call to [endNode] in
      // [doLogicalExpression].
      if (isAnd) {
        typeInferrer.assignedVariables.beginNode();
      }
      push(lhs);
    }
    assert(checkState(token, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
      ]),
    ]));
  }

  @override
  void endBinaryExpression(Token token, Token endToken) {
    assert(checkState(token, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
        ValueKinds.Selector,
      ]),
    ]));
    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);
    }
    assert(checkState(token, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.Initializer,
      ]),
    ]));
  }

  @override
  void beginPattern(Token token) {
    debugEvent("Pattern");
    if (token.lexeme == "||") {
      createAndEnterLocalScope(
          debugName: "rhs of a binary-or pattern",
          kind: ScopeKind.orPatternRight);
    } else {
      createAndEnterLocalScope(debugName: "pattern", kind: ScopeKind.pattern);
    }
  }

  @override
  void endPattern(Token token) {
    debugEvent("Pattern");
    assert(checkState(token, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
        ValueKinds.Pattern,
      ]),
    ]));
    Object pattern = pop()!;
    ScopeKind scopeKind = _localScope.kind;

    exitLocalScope(expectedScopeKinds: const [
      ScopeKind.pattern,
      ScopeKind.orPatternRight
    ]);

    // Bring the variables into the enclosing pattern scope, unless that was
    // the scope of the RHS of a binary-or pattern. In the latter case, the
    // joint variables will be declared in the enclosing scope instead later in
    // the process.
    //
    // Here we only handle the visibility of the pattern declared variables
    // within the pattern itself, so we declare the pattern variables in the
    // enclosing scope only if that enclosing scope is a pattern scope as well,
    // that is, if its kind is [ScopeKind.pattern] or
    // [ScopeKind.orPatternRight].
    bool enclosingScopeIsPatternScope = _localScope.kind == ScopeKind.pattern ||
        _localScope.kind == ScopeKind.orPatternRight;
    if (scopeKind != ScopeKind.orPatternRight && enclosingScopeIsPatternScope) {
      if (pattern is Pattern) {
        for (VariableDeclaration variable in pattern.declaredVariables) {
          declareVariable(variable, _localScope);
        }
      }
    }

    push(pattern);
  }

  @override
  void beginBinaryPattern(Token token) {
    debugEvent("BinaryPattern");
    assert(checkState(token, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
        ValueKinds.Pattern,
      ]),
    ]));

    // In case of the binary-or pattern, its LHS and RHS should contain
    // declarations of the variables with matching names, and we need to put
    // them into separate scopes to avoid the naming conflict. For that, we're
    // exiting the scope for the LHS, and the scope for the RHS will be created
    // when the RHS will be parsed. Additionally, since it's the first time
    // we're realizing that it's the binary-or pattern, we need to create the
    // enclosing scope for its joint variables as well.
    if (token.lexeme == "||") {
      Object lhsPattern = pop()!;

      // Exit the scope of the LHS.
      exitLocalScope(expectedScopeKinds: const [ScopeKind.pattern]);

      createAndEnterLocalScope(
          debugName: "joint variables of binary-or patterns",
          kind: ScopeKind.pattern);
      push(lhsPattern);
    }
  }

  @override
  void endBinaryPattern(Token token) {
    debugEvent("BinaryPattern");
    assert(checkState(token, [
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
        ValueKinds.Pattern,
      ]),
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
        ValueKinds.Pattern,
      ])
    ]));
    reportIfNotEnabled(
        libraryFeatures.patterns, token.charOffset, token.charCount);
    Pattern right = toPattern(pop());
    Pattern left = toPattern(pop());

    String operator = token.lexeme;
    switch (operator) {
      case '&&':
        push(forest.createAndPattern(token.charOffset, left, right));
        break;
      case '||':
        Map<String, VariableDeclaration> leftVariablesByName = {
          for (VariableDeclaration leftVariable in left.declaredVariables)
            leftVariable.name!: leftVariable
        };
        for (VariableDeclaration rightVariable in right.declaredVariables) {
          if (!leftVariablesByName.containsKey(rightVariable.name)) {
            addProblem(
                fasta.templateMissingVariablePattern
                    .withArguments(rightVariable.name!),
                left.fileOffset,
                noLength);
          }
        }
        Map<String, VariableDeclaration> rightVariablesByName = {
          for (VariableDeclaration rightVariable in right.declaredVariables)
            rightVariable.name!: rightVariable
        };
        for (VariableDeclaration leftVariable in left.declaredVariables) {
          if (!rightVariablesByName.containsKey(leftVariable.name)) {
            addProblem(
                fasta.templateMissingVariablePattern
                    .withArguments(leftVariable.name!),
                right.fileOffset,
                noLength);
          }
        }
        List<VariableDeclaration> jointVariables = [
          for (VariableDeclaration leftVariable in left.declaredVariables)
            forest.createVariableDeclaration(
                leftVariable.fileOffset, leftVariable.name!)
        ];
        for (VariableDeclaration variable in jointVariables) {
          declareVariable(variable, _localScope);
          typeInferrer.assignedVariables.declare(variable);
        }
        push(forest.createOrPattern(token.charOffset, left, right,
            orPatternJointVariables: jointVariables));
        break;
      // Coverage-ignore(suite): Not run.
      default:
        internalProblem(
            fasta.templateInternalProblemUnhandled
                .withArguments(operator, 'endBinaryPattern'),
            token.charOffset,
            uri);
    }
  }

  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 as Expression, 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 as Expression, name, right));
      }
    }
    assert(checkState(token, <ValueKind>[
      ValueKinds.Expression,
    ]));
  }

  /// Handle `a && b` and `a || b`.
  void doLogicalExpression(Token token) {
    assert(checkState(token, <ValueKind>[
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
      ]),
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
      ]),
    ]));
    Expression argument = popForValue();
    Expression receiver = pop() as Expression;
    Expression logicalExpression = forest.createLogicalExpression(
        offsetForToken(token), receiver, token.stringValue!, argument);
    push(logicalExpression);
    if (optional("&&", token)) {
      // This is matched by the call to [beginNode] in
      // [beginBinaryExpression].
      typeInferrer.assignedVariables.endNode(logicalExpression);
    }
    assert(checkState(token, <ValueKind>[
      ValueKinds.Expression,
    ]));
  }

  /// Handle `a ?? b`.
  void doIfNull(Token token) {
    assert(checkState(token, <ValueKind>[
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
      ]),
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
      ]),
    ]));
    Expression b = popForValue();
    Expression a = popForValue();
    push(new IfNullExpression(a, b)..fileOffset = offsetForToken(token));
    assert(checkState(token, <ValueKind>[
      ValueKinds.Expression,
    ]));
  }

  /// Handle `a?.b(...)`.
  void doIfNotNull(Token token) {
    assert(checkState(token, <ValueKind>[
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.Selector,
      ]),
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
        ValueKinds.Initializer,
      ]),
    ]));
    Object? send = pop();
    if (send is Selector) {
      push(send.withReceiver(pop(), token.charOffset, isNullAware: true));
    } else {
      pop();
      token = token.next!;
      push(buildProblem(fasta.templateExpectedIdentifier.withArguments(token),
          offsetForToken(token), lengthForToken(token)));
    }
    assert(checkState(token, <ValueKind>[
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.Initializer,
      ]),
    ]));
  }

  void doDotOrCascadeExpression(Token token) {
    assert(checkState(token, <ValueKind>[
      /* after . or .. */ unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.Selector,
      ]),
      /* before . or .. */ unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.ProblemBuilder,
        ValueKinds.Initializer,
      ]),
    ]));
    Object? send = pop();
    if (send is Selector) {
      Object? receiver = optional(".", token) ? pop() : popForValue();
      push(send.withReceiver(receiver, token.charOffset));
    } else if (send is IncompleteErrorGenerator) {
      // Pop the "receiver" and push the error.
      pop();
      push(send);
    } else {
      // Pop the "receiver" and push the error.
      pop();
      token = token.next!;
      push(buildProblem(fasta.templateExpectedIdentifier.withArguments(token),
          offsetForToken(token), lengthForToken(token)));
    }
    assert(checkState(token, <ValueKind>[
      unionOfKinds([
        ValueKinds.Expression,
        ValueKinds.Generator,
        ValueKinds.Initializer,
      ]),
    ]));
  }

  @override
  Expression buildUnresolvedError(String name, int charOffset,
      {Member? candidate,
      bool isSuper = false,
      required UnresolvedKind kind,
      bool isStatic = false,
      Arguments? arguments,
      Expression? rhs,
      LocatedMessage? message,
      int? length}) {
    // TODO(johnniwinther): Use [arguments] and [rhs] to create an unresolved
    // access expression to include in the invalid expression.
    if (length == null) {
      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) {
      switch (kind) {
        case UnresolvedKind.Unknown:
          assert(!isSuper);
          message = fasta.templateNameNotFound
              .withArguments(name)
              .withLocation(uri, charOffset, length);
          break;
        case UnresolvedKind.Member:
          message = warnUnresolvedMember(kernelName, charOffset,
                  isSuper: isSuper, reportWarning: false, context: context)
              .withLocation(uri, charOffset, length);
          break;
        case UnresolvedKind.Getter:
          message = warnUnresolvedGet(kernelName, charOffset,
                  isSuper: isSuper, reportWarning: false, context: context)
              .withLocation(uri, charOffset, length);
          break;
        case UnresolvedKind.Setter:
          message = warnUnresolvedSet(kernelName, charOffset,
                  isSuper: isSuper, reportWarning: false, context: context)
              .withLocation(uri, charOffset, length);
          break;
        case UnresolvedKind.Method:
          message = warnUnresolvedMethod(kernelName, charOffset,
                  isSuper: isSuper, reportWarning: false, context: context)
              .withLocation(uri, charOffset, length);
          break;
        case UnresolvedKind.Constructor:
          message = warnUnresolvedConstructor(kernelName, isSuper: isSuper)
              .withLocation(uri, charOffset, length);
          break;
      }
    }
    return buildProblem(
        message.messageObject, message.charOffset, message.length,
        context: context);
  }

  Message warnUnresolvedMember(Name name, int charOffset,
      {bool isSuper = false,
      bool reportWarning = true,
      List<LocatedMessage>? context}) {
    Message message = isSuper
        ?
        // Coverage-ignore(suite): Not run.
        fasta.templateSuperclassHasNoMember.withArguments(name.text)
        : fasta.templateMemberNotFound.withArguments(name.text);
    if (reportWarning) {
      // Coverage-ignore-block(suite): Not run.
      addProblemErrorIfConst(message, charOffset, name.text.length,
          context: context);
    }
    return message;
  }

  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) {
      // Coverage-ignore-block(suite): Not run.
      addProblemErrorIfConst(message, charOffset, name.text.length,
          context: context);
    }
    return message;
  }

  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) {
      // Coverage-ignore-block(suite): Not run.
      addProblemErrorIfConst(message, charOffset, name.text.length,
          context: context);
    }
    return message;
  }

  Message warnUnresolvedMethod(Name name, int charOffset,
      {bool isSuper = false,
      bool reportWarning = true,
      List<LocatedMessage>? context}) {
    String plainName = name.text;