// Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'dart:collection';

import 'package:analyzer/dart/analysis/declared_variables.dart';
import 'package:analyzer/dart/analysis/features.dart';
import 'package:analyzer/dart/ast/syntactic_entity.dart';
import 'package:analyzer/dart/ast/token.dart';
import 'package:analyzer/dart/ast/visitor.dart';
import 'package:analyzer/dart/element/element.dart';
import 'package:analyzer/dart/element/nullability_suffix.dart';
import 'package:analyzer/dart/element/type.dart';
import 'package:analyzer/dart/element/type_provider.dart';
import 'package:analyzer/error/listener.dart';
import 'package:analyzer/src/dart/ast/ast.dart';
import 'package:analyzer/src/dart/ast/extensions.dart';
import 'package:analyzer/src/dart/ast/token.dart';
import 'package:analyzer/src/dart/constant/from_environment_evaluator.dart';
import 'package:analyzer/src/dart/constant/has_type_parameter_reference.dart';
import 'package:analyzer/src/dart/constant/potentially_constant.dart';
import 'package:analyzer/src/dart/constant/utilities.dart';
import 'package:analyzer/src/dart/constant/value.dart';
import 'package:analyzer/src/dart/element/element.dart';
import 'package:analyzer/src/dart/element/member.dart';
import 'package:analyzer/src/dart/element/type.dart';
import 'package:analyzer/src/dart/element/type_algebra.dart';
import 'package:analyzer/src/dart/element/type_system.dart' show TypeSystemImpl;
import 'package:analyzer/src/diagnostic/diagnostic.dart';
import 'package:analyzer/src/error/codes.dart';
import 'package:analyzer/src/generated/engine.dart';
import 'package:analyzer/src/generated/java_core.dart';
import 'package:analyzer/src/task/api/model.dart';
import 'package:analyzer/src/utilities/extensions/collection.dart';
import 'package:analyzer/src/utilities/extensions/object.dart';

class ConstantEvaluationConfiguration {
  final Map<AstNode, AstNode> _errorNodes = {};

  /// We evaluate constant values using expressions stored in elements.
  /// But these expressions don't have offsets set.
  /// This includes elements and expressions of the file being resolved.
  /// So, to make sure that we report errors at right offsets, we "replace"
  /// these constant expressions.
  ///
  /// A similar issue happens for enum values, which are desugared into
  /// synthetic [InstanceCreationExpression], which never had any offsets.
  /// So, we remember that any errors should be reported at the corresponding
  /// [EnumConstantDeclaration]s.
  void addErrorNode({
    required AstNode? fromElement,
    required AstNode? fromAst,
  }) {
    if (fromElement != null && fromAst != null) {
      _errorNodes[fromElement] = fromAst;
    }
  }

  AstNode errorNode(AstNode node) {
    return _errorNodes[node] ?? node;
  }
}

/// Helper class encapsulating the methods for evaluating constants and
/// constant instance creation expressions.
class ConstantEvaluationEngine {
  /// The set of variables declared on the command line using '-D'.
  final DeclaredVariables _declaredVariables;

  final ConstantEvaluationConfiguration configuration;

  /// Initialize a newly created [ConstantEvaluationEngine].
  ///
  /// [declaredVariables] is the set of variables declared on the command
  /// line using '-D'.
  ConstantEvaluationEngine({
    required DeclaredVariables declaredVariables,
    required this.configuration,
  }) : _declaredVariables = declaredVariables;

  /// Compute the constant value associated with the given [constant].
  void computeConstantValue(ConstantEvaluationTarget constant) {
    if (constant is Element) {
      var element = constant as Element;
      constant = element.declaration as ConstantEvaluationTarget;
    }

    var library = constant.library as LibraryElementImpl;
    if (constant is ParameterElementImpl) {
      if (constant is ConstVariableElement) {
        var defaultValue = constant.constantInitializer;
        if (defaultValue != null) {
          var errorListener = RecordingErrorListener();
          var errorReporter = ErrorReporter(
            errorListener,
            constant.source!,
          );
          var constantVisitor = ConstantVisitor(this, library, errorReporter);
          var dartConstant = constantVisitor.evaluateConstant(defaultValue);
          constant.evaluationResult = dartConstant;
        } else {
          constant.evaluationResult = _nullObject(library);
        }
      }
    } else if (constant is VariableElementImpl) {
      var constantInitializer = constant.constantInitializer;
      if (constantInitializer != null) {
        var errorListener = RecordingErrorListener();
        var errorReporter = ErrorReporter(
          errorListener,
          constant.source!,
        );
        var constantVisitor = ConstantVisitor(this, library, errorReporter);
        var dartConstant =
            constantVisitor.evaluateConstant(constantInitializer);
        if (dartConstant is DartObjectImpl) {
          // Only check the type for truly const declarations (don't check final
          // fields with initializers, since their types may be generic.  The
          // type of the final field will be checked later, when the constructor
          // is invoked).
          if (constant.isConst) {
            if (!library.typeSystem
                .runtimeTypeMatch(dartConstant, constant.type)) {
              // If the static types are mismatched, an error would have already
              // been reported.
              if (library.typeSystem.isAssignableTo(
                  constantInitializer.typeOrThrow, constant.type)) {
                constant.evaluationResult = InvalidConstant.forEntity(
                    constantInitializer,
                    CompileTimeErrorCode.VARIABLE_TYPE_MISMATCH,
                    arguments: [
                      dartConstant.type.getDisplayString(),
                      constant.type.getDisplayString(),
                    ]);
                return;
              }
            }

            // Associate with the variable.
            dartConstant = DartObjectImpl.forVariable(dartConstant, constant);
          }

          var enumConstant = _enumConstant(constant);
          if (enumConstant != null) {
            dartConstant.updateEnumConstant(
              index: enumConstant.index,
              name: enumConstant.name,
            );
          }
        }

        constant.evaluationResult = dartConstant;
      }
    } else if (constant is ConstructorElementImpl) {
      if (constant.isConst) {
        // No evaluation needs to be done; constructor declarations are only in
        // the dependency graph to ensure that any constants referred to in
        // initializer lists and parameter defaults are evaluated before
        // invocations of the constructor.
        constant.isConstantEvaluated = true;
      }
    } else if (constant is ElementAnnotationImpl) {
      var constNode = constant.annotationAst;
      var element = constant.element;
      if (element is PropertyAccessorElement) {
        // The annotation is a reference to a compile-time constant variable.
        // Just copy the evaluation result.
        var variableElement =
            element.variable2?.declaration as VariableElementImpl?;
        var evaluationResult = variableElement?.evaluationResult;
        if (evaluationResult != null) {
          constant.evaluationResult = evaluationResult;
        } else {
          // This could happen in the event that the annotation refers to a
          // non-constant.  The error is detected elsewhere, so just silently
          // ignore it here.
          constant.evaluationResult = null;
        }
      } else if (element is ConstructorElement &&
          element.isConst &&
          constNode.arguments != null) {
        var errorListener = RecordingErrorListener();
        var errorReporter = ErrorReporter(
          errorListener,
          constant.source,
        );
        var constantVisitor = ConstantVisitor(this, library, errorReporter);
        var result = evaluateAndFormatErrorsInConstructorCall(
            library,
            constNode,
            element.returnType.typeArguments,
            constNode.arguments!.arguments,
            element,
            constantVisitor);
        constant.evaluationResult = result;
        constant.additionalErrors = errorListener.errors;
      } else {
        // This may happen for invalid code (e.g. failing to pass arguments
        // to an annotation which references a const constructor).  The error
        // is detected elsewhere, so just silently ignore it here.
        constant.evaluationResult = null;
      }
    } else if (constant is VariableElement) {
      // `constant` is a VariableElement but not a VariableElementImpl.  This
      // can happen sometimes in the case of invalid user code (for example, a
      // constant expression that refers to a non-static field inside a generic
      // class will wind up referring to a FieldMember).  The error is detected
      // elsewhere, so just silently ignore it here.
    } else {
      // Should not happen.
      assert(false);
      AnalysisEngine.instance.instrumentationService
          .logError("Constant value computer trying to compute "
              "the value of a node of type ${constant.runtimeType}");
      return;
    }
  }

  /// Determine which constant elements need to have their values computed
  /// prior to computing the value of [constant], and report them using
  /// [callback].
  void computeDependencies(
      ConstantEvaluationTarget constant, ReferenceFinderCallback callback) {
    if (constant is ConstFieldElementImpl && constant.isEnumConstant) {
      var enclosing = constant.enclosingElement;
      if (enclosing is EnumElementImpl) {
        if (enclosing.name == 'values') {
          return;
        }
        if (constant.name == enclosing.name) {
          return;
        }
      }
    }

    ReferenceFinder referenceFinder = ReferenceFinder(callback);
    if (constant is ConstructorElement) {
      constant = constant.declaration;
    }
    if (constant is VariableElement) {
      var declaration = constant.declaration as VariableElementImpl;
      var initializer = declaration.constantInitializer;
      if (initializer != null) {
        initializer.accept(referenceFinder);
      }
    } else if (constant is ConstructorElementImpl) {
      if (constant.isConst) {
        var redirectedConstructor = getConstRedirectedConstructor(constant);
        if (redirectedConstructor != null) {
          var redirectedConstructorBase = redirectedConstructor.declaration;
          callback(redirectedConstructorBase);
          return;
        } else if (constant.isFactory) {
          // Factory constructor, but getConstRedirectedConstructor returned
          // null.  This can happen if we're visiting one of the special
          // external const factory constructors in the SDK, or if the code
          // contains errors (such as delegating to a non-const constructor, or
          // delegating to a constructor that can't be resolved).  In any of
          // these cases, we'll evaluate calls to this constructor without
          // having to refer to any other constants.  So we don't need to report
          // any dependencies.
          return;
        }
        bool defaultSuperInvocationNeeded = true;
        var initializers = constant.constantInitializers;
        for (ConstructorInitializer initializer in initializers) {
          if (initializer is SuperConstructorInvocation ||
              initializer is RedirectingConstructorInvocation) {
            defaultSuperInvocationNeeded = false;
          }
          initializer.accept(referenceFinder);
        }
        if (defaultSuperInvocationNeeded) {
          // No explicit superconstructor invocation found, so we need to
          // manually insert a reference to the implicit superconstructor.
          var superclass = constant.returnType.superclass;
          if (superclass != null && !superclass.isDartCoreObject) {
            var unnamedConstructor =
                superclass.element.unnamedConstructor?.declaration;
            if (unnamedConstructor != null && unnamedConstructor.isConst) {
              callback(unnamedConstructor);
            }
          }
        }
        for (FieldElement field in constant.enclosingElement.fields) {
          // Note: non-static const isn't allowed but we handle it anyway so
          // that we won't be confused by incorrect code.
          if ((field.isFinal || field.isConst) &&
              !field.isStatic &&
              field.hasInitializer) {
            callback(field);
          }
        }
        for (ParameterElement parameterElement in constant.parameters) {
          callback(parameterElement);
        }
      }
    } else if (constant is ElementAnnotationImpl) {
      Annotation constNode = constant.annotationAst;
      var element = constant.element;
      if (element is PropertyAccessorElement) {
        // The annotation is a reference to a compile-time constant variable,
        // so it depends on the variable.
        if (element.variable2 case var variable?) {
          callback(variable.declaration);
        }
      } else if (element is ConstructorElement) {
        // The annotation is a constructor invocation, so it depends on the
        // constructor.
        callback(element.declaration);
      } else {
        // This could happen in the event of invalid code.  The error will be
        // reported at constant evaluation time.
      }
      if (constNode.arguments != null) {
        constNode.arguments!.accept(referenceFinder);
      }
    } else if (constant is VariableElement) {
      // `constant` is a VariableElement but not a VariableElementImpl.  This
      // can happen sometimes in the case of invalid user code (for example, a
      // constant expression that refers to a non-static field inside a generic
      // class will wind up referring to a FieldMember).  So just don't bother
      // computing any dependencies.
    } else {
      // Should not happen.
      assert(false);
      AnalysisEngine.instance.instrumentationService
          .logError("Constant value computer trying to compute "
              "the value of a node of type ${constant.runtimeType}");
    }
  }

  /// Evaluate the constructor call and format any [InvalidConstants] if found.
  Constant evaluateAndFormatErrorsInConstructorCall(
    LibraryElementImpl library,
    AstNode node,
    List<DartType>? typeArguments,
    List<Expression> arguments,
    ConstructorElement constructor,
    ConstantVisitor constantVisitor, {
    ConstructorInvocation? invocation,
  }) {
    var result = _InstanceCreationEvaluator.evaluate(
      this,
      _declaredVariables,
      library,
      node,
      constructor,
      typeArguments,
      arguments,
      constantVisitor,
      invocation: invocation,
    );
    if (result is! InvalidConstant) {
      return result;
    }

    // If we found an evaluation exception, report a context message linking to
    // where the exception was found.
    if (result.isRuntimeException) {
      var formattedMessage =
          formatList(result.errorCode.problemMessage, result.arguments);
      var contextMessage = DiagnosticMessageImpl(
        filePath: library.source.fullName,
        length: result.length,
        message: "The exception is '$formattedMessage' and occurs here.",
        offset: result.offset,
        url: null,
      );
      var errorNode = configuration.errorNode(node);
      result = InvalidConstant.forEntity(
          errorNode, CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION,
          contextMessages: [...result.contextMessages, contextMessage]);
    }

    return result;
  }

  Constant evaluateConstructorCall(
    LibraryElementImpl library,
    AstNode node,
    List<DartType>? typeArguments,
    List<Expression> arguments,
    ConstructorElement constructor,
    ConstantVisitor constantVisitor, {
    ConstructorInvocation? invocation,
  }) {
    return _InstanceCreationEvaluator.evaluate(
      this,
      _declaredVariables,
      library,
      node,
      constructor,
      typeArguments,
      arguments,
      constantVisitor,
      invocation: invocation,
    );
  }

  /// Generate an error indicating that the given [constant] is not a valid
  /// compile-time constant because it references at least one of the constants
  /// in the given [cycle], each of which directly or indirectly references the
  /// constant.
  void generateCycleError(
    Iterable<ConstantEvaluationTarget> cycle,
    ConstantEvaluationTarget constant,
  ) {
    if (constant is VariableElement) {
      RecordingErrorListener errorListener = RecordingErrorListener();
      ErrorReporter errorReporter = ErrorReporter(
        errorListener,
        constant.source!,
      );
      // TODO(paulberry): It would be really nice if we could extract enough
      // information from the 'cycle' argument to provide the user with a
      // description of the cycle.
      errorReporter.atElement(
        constant,
        CompileTimeErrorCode.RECURSIVE_COMPILE_TIME_CONSTANT,
      );
      (constant as VariableElementImpl).evaluationResult =
          InvalidConstant.forElement(
              constant, CompileTimeErrorCode.RECURSIVE_COMPILE_TIME_CONSTANT);
    } else if (constant is ConstructorElement) {
      // We don't report cycle errors on constructor declarations here since
      // there is nowhere to put the error information.
      //
      // Instead we will report an error at each constructor in
      // [ConstantVerifier.visitConstructorDeclaration].
    } else {
      // Should not happen.  Formal parameter defaults and annotations should
      // never appear as part of a cycle because they can't be referred to.
      assert(false);
      AnalysisEngine.instance.instrumentationService
          .logError("Constant value computer trying to report a cycle error "
              "for a node of type ${constant.runtimeType}");
    }
  }

  /// If [constructor] redirects to another const constructor, return the
  /// const constructor it redirects to.  Otherwise return `null`.
  static ConstructorElement? getConstRedirectedConstructor(
      ConstructorElement constructor) {
    if (!constructor.isFactory) {
      return null;
    }
    var typeProvider = constructor.library.typeProvider;
    if (constructor.enclosingElement == typeProvider.symbolElement) {
      // The dart:core.Symbol has a const factory constructor that redirects
      // to dart:_internal.Symbol.  That in turn redirects to an external
      // const constructor, which we won't be able to evaluate.
      // So stop following the chain of redirections at dart:core.Symbol, and
      // let [evaluateInstanceCreationExpression] handle it specially.
      return null;
    }
    var redirectedConstructor = constructor.redirectedConstructor;
    if (redirectedConstructor == null) {
      // This can happen if constructor is an external factory constructor.
      return null;
    }
    if (!redirectedConstructor.isConst) {
      // Delegating to a non-const constructor--this is not allowed (and
      // is checked elsewhere--see
      // [ErrorVerifier.checkForRedirectToNonConstConstructor()]).
      return null;
    }
    return redirectedConstructor;
  }

  static _EnumConstant? _enumConstant(VariableElementImpl element) {
    if (element is ConstFieldElementImpl && element.isEnumConstant) {
      var enum_ = element.enclosingElement;
      if (enum_ is EnumElementImpl) {
        var index = enum_.constants.indexOf(element);
        assert(index >= 0);
        return _EnumConstant(
          index: index,
          name: element.name,
        );
      }
    }
    return null;
  }

  static DartObjectImpl _nullObject(LibraryElementImpl library) {
    return DartObjectImpl(
      library.typeSystem,
      library.typeProvider.nullType,
      NullState.NULL_STATE,
    );
  }

  /// Returns the representation of a constant expression which has an
  /// [InvalidType], with the given [defaultType].
  static DartObjectImpl _unresolvedObject(
      LibraryElementImpl library, DartType defaultType) {
    // TODO(kallentu): Use a better representation of an unresolved object that
    // doesn't need to rely on NullState.
    return DartObjectImpl(
      library.typeSystem,
      defaultType,
      NullState(isInvalid: true),
    );
  }
}

/// Interface for [AnalysisTarget]s for which constant evaluation can be
/// performed.
abstract class ConstantEvaluationTarget extends AnalysisTarget {
  /// Return the [AnalysisContext] which should be used to evaluate this
  /// constant.
  AnalysisContext get context;

  /// Return whether this constant is evaluated.
  bool get isConstantEvaluated;

  /// The library with this constant.
  LibraryElement? get library;
}

/// A visitor used to evaluate constant expressions to produce their
/// compile-time value.
class ConstantVisitor extends UnifyingAstVisitor<Constant> {
  /// The evaluation engine used to access the feature set, type system, and
  /// type provider.
  final ConstantEvaluationEngine _evaluationEngine;

  /// The library that contains the constant expression being evaluated.
  final LibraryElementImpl _library;

  /// A mapping of variable names to runtime values.
  final Map<String, DartObjectImpl>? _lexicalEnvironment;

  /// A mapping of type parameter names to runtime values (types).
  final Map<TypeParameterElement, DartType>? _lexicalTypeEnvironment;

  final Substitution? _substitution;

  /// Error reporter that we use to report errors accumulated while computing
  /// the constant.
  final ErrorReporter _errorReporter;

  /// Helper class used to compute constant values.
  late final DartObjectComputer _dartObjectComputer;

  /// Initialize a newly created constant visitor. The [evaluationEngine] is
  /// used to evaluate instance creation expressions. The [lexicalEnvironment]
  /// is a map containing values which should override identifiers, or `null` if
  /// no overriding is necessary. The [_errorReporter] is used to report errors
  /// found during evaluation.  The [validator] is used by unit tests to verify
  /// correct dependency analysis.
  ///
  /// The [substitution] is specified for instance creations.
  ConstantVisitor(
    this._evaluationEngine,
    this._library,
    this._errorReporter, {
    Map<String, DartObjectImpl>? lexicalEnvironment,
    Map<TypeParameterElement, DartType>? lexicalTypeEnvironment,
    Substitution? substitution,
  })  : _lexicalEnvironment = lexicalEnvironment,
        _lexicalTypeEnvironment = lexicalTypeEnvironment,
        _substitution = substitution {
    _dartObjectComputer = DartObjectComputer(
      typeSystem,
      _library.featureSet,
    );
  }

  /// Convenience getter to gain access to the [evaluationEngine]'s type system.
  TypeSystemImpl get typeSystem => _library.typeSystem;

  /// Convenience getter to gain access to the [evaluationEngine]'s type
  /// provider.
  TypeProvider get _typeProvider => _library.typeProvider;

  /// Evaluates and reports an error if the evaluation result of [node] is an
  /// [InvalidConstant].
  ///
  /// If [InvalidConstant.avoidReporting] is marked `true`, no error is
  /// reported.
  Constant evaluateAndReportInvalidConstant(AstNode node) {
    var result = evaluateConstant(node);
    if (result case InvalidConstant(avoidReporting: false)) {
      _errorReporter.atOffset(
        offset: result.offset,
        length: result.length,
        errorCode: result.errorCode,
        arguments: result.arguments,
        contextMessages: result.contextMessages,
      );
    }
    return result;
  }

  /// Evaluates the expression of [node] using this [ConstantVisitor].
  ///
  /// Returns the resulting constant value, which can be an [InvalidConstant]
  /// if the expression fails to evaluate to a constant value.
  ///
  /// The [ConstantVisitor] can't return any `null` values even though
  /// [UnifyingAstVisitor] allows it. If we encounter an unexpected `null`
  /// value, we will return an [InvalidConstant] instead.
  Constant evaluateConstant(AstNode node) {
    var result = node.accept(this);
    if (result == null) {
      // Should never reach this.
      throw UnsupportedError(
        'The constant evaluator returned an unexpected null value.',
      );
    }
    return result;
  }

  @override
  Constant visitAdjacentStrings(AdjacentStrings node) {
    return _concatenateNodes(node, node.strings);
  }

  @override
  Constant visitAsExpression(AsExpression node) {
    var expression = evaluateConstant(node.expression);
    if (expression is! DartObjectImpl) {
      return expression;
    }
    var type = evaluateConstant(node.type);
    if (type is! DartObjectImpl) {
      return type;
    }
    return _dartObjectComputer.castToType(node, expression, type);
  }

  @override
  Constant visitBinaryExpression(BinaryExpression node) {
    var operatorElement = node.staticElement;
    var operatorContainer = operatorElement?.enclosingElement;
    switch (operatorContainer) {
      case ExtensionElement():
        return InvalidConstant.forEntity(
          node,
          CompileTimeErrorCode.CONST_EVAL_EXTENSION_METHOD,
        );
      case ExtensionTypeElement():
        return InvalidConstant.forEntity(
          node,
          CompileTimeErrorCode.CONST_EVAL_EXTENSION_TYPE_METHOD,
        );
    }

    TokenType operatorType = node.operator.type;
    var leftResult = evaluateConstant(node.leftOperand);
    if (leftResult is! DartObjectImpl) {
      return leftResult;
    }

    // Used for the [DartObjectComputer], which will handle any exceptions.
    DartObjectImpl rightOperandComputer() {
      var constant = evaluateConstant(node.rightOperand);
      switch (constant) {
        case DartObjectImpl():
          return constant;
        case InvalidConstant():
          throw EvaluationException(constant.errorCode);
        default:
          throw EvaluationException(CompileTimeErrorCode.INVALID_CONSTANT);
      }
    }

    // Evaluate lazy operators.
    if (operatorType == TokenType.AMPERSAND_AMPERSAND) {
      if (leftResult.toBoolValue() == false) {
        var error = _reportNotPotentialConstants(node.rightOperand);
        if (error is InvalidConstant) {
          return error;
        }
      }
      return _dartObjectComputer.lazyAnd(
          node, leftResult, rightOperandComputer);
    } else if (operatorType == TokenType.BAR_BAR) {
      if (leftResult.toBoolValue() == true) {
        var error = _reportNotPotentialConstants(node.rightOperand);
        if (error is InvalidConstant) {
          return error;
        }
      }
      return _dartObjectComputer.lazyOr(node, leftResult, rightOperandComputer);
    } else if (operatorType == TokenType.QUESTION_QUESTION) {
      if (leftResult.isNull != true) {
        var error = _reportNotPotentialConstants(node.rightOperand);
        if (error is InvalidConstant) {
          return error;
        }
      }
      return _dartObjectComputer.lazyQuestionQuestion(
          node, leftResult, () => evaluateConstant(node.rightOperand));
    }

    // Evaluate eager operators.
    var rightResult = evaluateConstant(node.rightOperand);
    if (rightResult is! DartObjectImpl) {
      return rightResult;
    }
    if (operatorType == TokenType.AMPERSAND) {
      return _dartObjectComputer.eagerAnd(node, leftResult, rightResult);
    } else if (operatorType == TokenType.BANG_EQ) {
      return _dartObjectComputer.notEqual(node, leftResult, rightResult);
    } else if (operatorType == TokenType.BAR) {
      return _dartObjectComputer.eagerOr(node, leftResult, rightResult);
    } else if (operatorType == TokenType.CARET) {
      return _dartObjectComputer.eagerXor(node, leftResult, rightResult);
    } else if (operatorType == TokenType.EQ_EQ) {
      return _dartObjectComputer.equalEqual(node, leftResult, rightResult);
    } else if (operatorType == TokenType.GT) {
      return _dartObjectComputer.greaterThan(node, leftResult, rightResult);
    } else if (operatorType == TokenType.GT_EQ) {
      return _dartObjectComputer.greaterThanOrEqual(
          node, leftResult, rightResult);
    } else if (operatorType == TokenType.GT_GT) {
      return _dartObjectComputer.shiftRight(node, leftResult, rightResult);
    } else if (operatorType == TokenType.GT_GT_GT) {
      return _dartObjectComputer.logicalShiftRight(
          node, leftResult, rightResult);
    } else if (operatorType == TokenType.LT) {
      return _dartObjectComputer.lessThan(node, leftResult, rightResult);
    } else if (operatorType == TokenType.LT_EQ) {
      return _dartObjectComputer.lessThanOrEqual(node, leftResult, rightResult);
    } else if (operatorType == TokenType.LT_LT) {
      return _dartObjectComputer.shiftLeft(node, leftResult, rightResult);
    } else if (operatorType == TokenType.MINUS) {
      return _dartObjectComputer.minus(node, leftResult, rightResult);
    } else if (operatorType == TokenType.PERCENT) {
      return _dartObjectComputer.remainder(node, leftResult, rightResult);
    } else if (operatorType == TokenType.PLUS) {
      return _dartObjectComputer.add(node, leftResult, rightResult);
    } else if (operatorType == TokenType.STAR) {
      return _dartObjectComputer.times(node, leftResult, rightResult);
    } else if (operatorType == TokenType.SLASH) {
      return _dartObjectComputer.divide(node, leftResult, rightResult);
    } else if (operatorType == TokenType.TILDE_SLASH) {
      return _dartObjectComputer.integerDivide(node, leftResult, rightResult);
    } else {
      // TODO(srawlins): Use a specific error code.
      // https://github.com/dart-lang/sdk/issues/47061
      return InvalidConstant.genericError(node);
    }
  }

  @override
  Constant visitBooleanLiteral(BooleanLiteral node) {
    return DartObjectImpl(
      typeSystem,
      _typeProvider.boolType,
      BoolState.from(node.value),
    );
  }

  @override
  Constant visitConditionalExpression(ConditionalExpression node) {
    var condition = node.condition;
    var conditionConstant = evaluateConstant(condition);
    if (conditionConstant is! DartObjectImpl) {
      return conditionConstant;
    }

    if (!conditionConstant.isBool) {
      return InvalidConstant.forEntity(
          condition, CompileTimeErrorCode.CONST_EVAL_TYPE_BOOL);
    }
    conditionConstant = _dartObjectComputer.applyBooleanConversion(
        condition, conditionConstant);
    if (conditionConstant is! DartObjectImpl) {
      return conditionConstant;
    }

    var conditionResultBool = conditionConstant.toBoolValue();
    if (conditionResultBool == true) {
      var error = _reportNotPotentialConstants(node.elseExpression);
      if (error is InvalidConstant) {
        return error;
      }
      return evaluateConstant(node.thenExpression);
    } else if (conditionResultBool == false) {
      var error = _reportNotPotentialConstants(node.thenExpression);
      if (error is InvalidConstant) {
        return error;
      }
      return evaluateConstant(node.elseExpression);
    } else {
      var thenConstant = evaluateConstant(node.thenExpression);
      if (thenConstant is InvalidConstant) {
        return thenConstant;
      }
      var elseConstant = evaluateConstant(node.elseExpression);
      if (elseConstant is InvalidConstant) {
        return elseConstant;
      }
      return DartObjectImpl.validWithUnknownValue(
        typeSystem,
        node.typeOrThrow,
      );
    }
  }

  @override
  Constant visitConstructorReference(ConstructorReference node) {
    var constructorFunctionType = node.typeOrThrow;
    if (constructorFunctionType is! FunctionType) {
      return InvalidConstant.forEntity(
          node, CompileTimeErrorCode.INVALID_CONSTANT);
    }
    var classType = constructorFunctionType.returnType as InterfaceType;
    var typeArguments = classType.typeArguments;
    // The result is already instantiated during resolution;
    // [_dartObjectComputer.typeInstantiate] is unnecessary.
    var typeElement = node.constructorName.type.element as TypeDefiningElement;

    TypeAliasElement? viaTypeAlias;
    if (typeElement is TypeAliasElementImpl) {
      if (constructorFunctionType.typeFormals.isNotEmpty &&
          !typeElement.isProperRename) {
        // The type alias is not a proper rename of the aliased class, so
        // the constructor tear-off is distinct from the associated
        // constructor function of the aliased class.
        viaTypeAlias = typeElement;
      }
    }

    var constructorElement = node.constructorName.staticElement?.declaration
        .ifTypeOrNull<ConstructorElementImpl>();
    if (constructorElement == null) {
      return InvalidConstant.forEntity(
          node, CompileTimeErrorCode.INVALID_CONSTANT);
    }

    return DartObjectImpl(
      typeSystem,
      node.typeOrThrow,
      FunctionState(constructorElement,
          typeArguments: typeArguments, viaTypeAlias: viaTypeAlias),
    );
  }

  @override
  Constant visitDoubleLiteral(DoubleLiteral node) {
    return DartObjectImpl(
      typeSystem,
      _typeProvider.doubleType,
      DoubleState(node.value),
    );
  }

  @override
  Constant visitFunctionReference(FunctionReference node) {
    var functionResult = evaluateConstant(node.function);
    if (functionResult is! DartObjectImpl) {
      return functionResult;
    }

    // Report an error if any of the _inferred_ type argument types refer to a
    // type parameter. If, however, `node.typeArguments` is not `null`, then
    // any type parameters contained therein are reported as non-constant in
    // [ConstantVerifier].
    if (node.typeArguments == null) {
      var typeArgumentTypes = node.typeArgumentTypes;
      if (typeArgumentTypes != null) {
        var instantiatedTypeArgumentTypes = typeArgumentTypes.map((type) {
          if (type is TypeParameterType) {
            return _lexicalTypeEnvironment?[type.element] ?? type;
          } else {
            return type;
          }
        });
        if (instantiatedTypeArgumentTypes.any(hasTypeParameterReference)) {
          return InvalidConstant.forEntity(node,
              CompileTimeErrorCode.CONST_WITH_TYPE_PARAMETERS_FUNCTION_TEAROFF);
        }
      }
    }

    var typeArgumentList = node.typeArguments;
    if (typeArgumentList == null) {
      return _instantiateFunctionType(node, functionResult);
    }

    var typeArguments = <DartType>[];
    for (var typeArgument in typeArgumentList.arguments) {
      var typeArgumentConstant = evaluateConstant(typeArgument);
      switch (typeArgumentConstant) {
        case InvalidConstant(
            errorCode: CompileTimeErrorCode.CONST_TYPE_PARAMETER
          ):
          // If there's a type parameter error in the evaluated constant, we
          // convert the message to a more specific function reference error.
          return InvalidConstant.forEntity(typeArgument,
              CompileTimeErrorCode.CONST_WITH_TYPE_PARAMETERS_FUNCTION_TEAROFF);
        case InvalidConstant():
          return typeArgumentConstant;
        case DartObjectImpl():
          var typeArgumentType = typeArgumentConstant.toTypeValue();
          if (typeArgumentType == null) {
            return InvalidConstant.forEntity(
                typeArgument, CompileTimeErrorCode.INVALID_CONSTANT);
          }
          // TODO(srawlins): Test type alias types (`typedef i = int`) used as
          // type arguments. Possibly change implementation based on
          // canonicalization rules.
          typeArguments.add(typeArgumentType);
      }
    }
    return _dartObjectComputer.typeInstantiate(
        functionResult, typeArguments, node.function, typeArgumentList);
  }

  @override
  Constant visitGenericFunctionType(GenericFunctionType node) {
    return DartObjectImpl(
      typeSystem,
      _typeProvider.typeType,
      TypeState(node.type),
    );
  }

  @override
  Constant visitInstanceCreationExpression(InstanceCreationExpression node) {
    if (!node.isConst) {
      // TODO(srawlins): Use a specific error code.
      // https://github.com/dart-lang/sdk/issues/47061
      return InvalidConstant.genericError(node);
    }
    var constructor = node.constructorName.staticElement;
    if (constructor == null) {
      // Couldn't resolve the constructor so we can't compute a value.  No
      // problem - the error has already been reported.
      // TODO(kallentu): Use a better error code for this.
      return InvalidConstant.forEntity(
          node, CompileTimeErrorCode.INVALID_CONSTANT);
    }

    return _evaluationEngine.evaluateAndFormatErrorsInConstructorCall(
      _library,
      node,
      constructor.returnType.typeArguments,
      node.argumentList.arguments,
      constructor,
      this,
    );
  }

  @override
  Constant visitIntegerLiteral(IntegerLiteral node) {
    if (node.staticType == _typeProvider.doubleType) {
      return DartObjectImpl(
        typeSystem,
        _typeProvider.doubleType,
        DoubleState(node.value?.toDouble()),
      );
    }
    return DartObjectImpl(
      typeSystem,
      _typeProvider.intType,
      IntState(node.value),
    );
  }

  @override
  Constant visitInterpolationExpression(InterpolationExpression node) {
    var result = evaluateConstant(node.expression);
    if (result is! DartObjectImpl) {
      return result;
    }

    if (!result.isBoolNumStringOrNull) {
      return InvalidConstant.forEntity(
          node, CompileTimeErrorCode.CONST_EVAL_TYPE_BOOL_NUM_STRING);
    }
    return _dartObjectComputer.performToString(node, result);
  }

  @override
  Constant visitInterpolationString(InterpolationString node) {
    return DartObjectImpl(
      typeSystem,
      _typeProvider.stringType,
      StringState(node.value),
    );
  }

  @override
  Constant visitIsExpression(IsExpression node) {
    var expression = evaluateConstant(node.expression);
    if (expression is! DartObjectImpl) {
      return expression;
    }
    var type = evaluateConstant(node.type);
    if (type is! DartObjectImpl) {
      return type;
    }
    return _dartObjectComputer.typeTest(node, expression, type);
  }

  @override
  Constant visitListLiteral(ListLiteral node) {
    if (!node.isConst) {
      return InvalidConstant.forEntity(
          node, CompileTimeErrorCode.MISSING_CONST_IN_LIST_LITERAL);
    }
    var nodeType = node.staticType;
    var elementType =
        nodeType is InterfaceType && nodeType.typeArguments.isNotEmpty
            ? nodeType.typeArguments[0]
            : _typeProvider.dynamicType;
    var listType = _typeProvider.listType(elementType);
    var list = <DartObjectImpl>[];
    return _buildListConstant(
      list,
      node.elements,
      typeSystem,
      listType,
      elementType,
    );
  }

  @override
  Constant visitMethodInvocation(MethodInvocation node) {
    var element = node.methodName.staticElement;
    if (element is FunctionElement) {
      if (element.name == "identical") {
        NodeList<Expression> arguments = node.argumentList.arguments;
        if (arguments.length == 2) {
          var enclosingElement = element.enclosingElement;
          if (enclosingElement is CompilationUnitElement) {
            LibraryElement library = enclosingElement.library;
            if (library.isDartCore) {
              var leftArgument = evaluateConstant(arguments[0]);
              if (leftArgument is! DartObjectImpl) {
                return leftArgument;
              }
              var rightArgument = evaluateConstant(arguments[1]);
              if (rightArgument is! DartObjectImpl) {
                return rightArgument;
              }
              return _dartObjectComputer.isIdentical(
                  node, leftArgument, rightArgument);
            }
          }
        }
      }
    }

    // Some methods aren't resolved by the time we are evaluating it. We'll mark
    // it and return immediately.
    if (node.staticType is InvalidType) {
      return InvalidConstant.forEntity(
          node, CompileTimeErrorCode.INVALID_CONSTANT,
          isUnresolved: true);
    }

    return InvalidConstant.forEntity(
        node, CompileTimeErrorCode.CONST_EVAL_METHOD_INVOCATION);
  }

  @override
  Constant visitNamedExpression(NamedExpression node) =>
      evaluateConstant(node.expression);

  @override
  Constant visitNamedType(NamedType node) {
    var type = node.typeOrThrow;

    if (node.isTypeLiteralInConstantPattern &&
        hasTypeParameterReference(type)) {
      return InvalidConstant.forEntity(
          node, CompileTimeErrorCode.CONST_TYPE_PARAMETER);
    } else if (node.isDeferred) {
      return _getDeferredLibraryError(node, node.name2);
    }

    if (_substitution != null) {
      type = _substitution.substituteType(type);
    }

    return _getConstantValue(
      errorNode: node,
      expression: null,
      identifier: null,
      element: node.element,
      givenType: type,
    );
  }

  @override
  Constant visitNode(AstNode node) {
    // TODO(srawlins): Use a specific error code.
    // https://github.com/dart-lang/sdk/issues/47061
    return InvalidConstant.genericError(node);
  }

  @override
  Constant visitNullLiteral(NullLiteral node) {
    return ConstantEvaluationEngine._nullObject(_library);
  }

  @override
  Constant visitParenthesizedExpression(ParenthesizedExpression node) =>
      evaluateConstant(node.expression);

  @override
  Constant visitPrefixedIdentifier(PrefixedIdentifier node) {
    var prefixNode = node.prefix;
    var prefixElement = prefixNode.staticElement;

    // A top-level constant, imported with a prefix.
    if (prefixElement is PrefixElement) {
      if (node.isDeferred) {
        return _getDeferredLibraryError(node, node.identifier);
      }
    } else if (prefixElement is! ExtensionElement) {
      var prefixResult = evaluateConstant(prefixNode);
      if (prefixResult is! DartObjectImpl) {
        return prefixResult;
      }

      // For example, `String.length`.
      if (prefixElement is! InterfaceElement) {
        var propertyAccessResult =
            _evaluatePropertyAccess(prefixResult, node.identifier, node);
        if (propertyAccessResult != null) {
          return propertyAccessResult;
        }
      }
    }

    // Validate prefixed identifier.
    return _getConstantValue(
      errorNode: node,
      expression: node,
      identifier: node.identifier,
      element: node.identifier.staticElement,
    );
  }

  @override
  Constant visitPrefixExpression(PrefixExpression node) {
    var operatorElement = node.staticElement;
    var operatorContainer = operatorElement?.enclosingElement;
    switch (operatorContainer) {
      case ExtensionElement():
        return InvalidConstant.forEntity(
          node,
          CompileTimeErrorCode.CONST_EVAL_EXTENSION_METHOD,
        );
      case ExtensionTypeElement():
        return InvalidConstant.forEntity(
          node,
          CompileTimeErrorCode.CONST_EVAL_EXTENSION_TYPE_METHOD,
        );
    }

    var operand = evaluateConstant(node.operand);
    if (operand is! DartObjectImpl) {
      return operand;
    }
    if (node.operator.type == TokenType.BANG) {
      return _dartObjectComputer.logicalNot(node, operand);
    } else if (node.operator.type == TokenType.TILDE) {
      return _dartObjectComputer.bitNot(node, operand);
    } else if (node.operator.type == TokenType.MINUS) {
      return _dartObjectComputer.negated(node, operand);
    } else {
      // TODO(srawlins): Use a specific error code.
      // https://github.com/dart-lang/sdk/issues/47061
      return InvalidConstant.genericError(node);
    }
  }

  @override
  Constant visitPropertyAccess(PropertyAccess node) {
    var target = node.target;
    if (target != null) {
      if (target is PrefixedIdentifier &&
          (target.staticElement is ExtensionElement ||
              target.staticElement is ExtensionTypeElement)) {
        var prefix = target.prefix;
        if (prefix.staticElement is PrefixElement && target.isDeferred) {
          return _getDeferredLibraryError(node, target.identifier);
        }

        // For example, `async.FutureExtensions.wait`.
        return _getConstantValue(
          errorNode: node,
          expression: node,
          identifier: node.propertyName,
          element: node.propertyName.staticElement,
        );
      }
      var prefixResult = evaluateConstant(target);
      if (prefixResult is! DartObjectImpl) {
        return prefixResult;
      }

      var propertyAccessResult =
          _evaluatePropertyAccess(prefixResult, node.propertyName, node);
      if (propertyAccessResult != null) {
        return propertyAccessResult;
      }
    }
    return _getConstantValue(
      errorNode: node,
      expression: node,
      identifier: node.propertyName,
      element: node.propertyName.staticElement,
    );
  }

  @override
  Constant visitRecordLiteral(RecordLiteral node) {
    var positionalFields = <DartObjectImpl>[];
    var namedFields = <String, DartObjectImpl>{};
    for (var field in node.fields) {
      if (field is NamedExpression) {
        var name = field.name.label.name;
        var value = evaluateConstant(field.expression);
        if (value is! DartObjectImpl) {
          return value;
        }
        namedFields[name] = value;
      } else {
        var value = evaluateConstant(field);
        if (value is! DartObjectImpl) {
          return value;
        }
        positionalFields.add(value);
      }
    }

    var nodeType = RecordType(
      positional: positionalFields.map((e) => e.type).toList(),
      named: namedFields.map((name, value) => MapEntry(name, value.type)),
      nullabilitySuffix: NullabilitySuffix.none,
    );

    return DartObjectImpl(
        typeSystem, nodeType, RecordState(positionalFields, namedFields));
  }

  @override
  Constant? visitRecordTypeAnnotation(RecordTypeAnnotation node) {
    return DartObjectImpl(
      typeSystem,
      _typeProvider.typeType,
      TypeState(node.type),
    );
  }

  @override
  Constant visitSetOrMapLiteral(SetOrMapLiteral node) {
    // Note: due to dartbug.com/33441, it's possible that a set/map literal
    // resynthesized from a summary will have neither its `isSet` or `isMap`
    // boolean set to `true`.  We work around the problem by assuming such
    // literals are maps.
    // TODO(paulberry): when dartbug.com/33441 is fixed, add an assertion here
    // to verify that `node.isSet == !node.isMap`.
    bool isMap = !node.isSet;
    if (isMap) {
      if (!node.isConst) {
        return InvalidConstant.forEntity(
            node, CompileTimeErrorCode.MISSING_CONST_IN_MAP_LITERAL);
      }
      var keyType = _typeProvider.dynamicType;
      var valueType = _typeProvider.dynamicType;
      var nodeType = node.staticType;
      if (nodeType is InterfaceType) {
        var typeArguments = nodeType.typeArguments;
        if (typeArguments.length >= 2) {
          keyType = typeArguments[0];
          valueType = typeArguments[1];
        }
      }
      var mapType = _typeProvider.mapType(keyType, valueType);
      var map = <DartObjectImpl, DartObjectImpl>{};
      var result = _buildMapConstant(map, node.elements, typeSystem, mapType);
      if (result is InvalidConstant && !node.isMap) {
        // We don't report the error if we know this is an ambiguous map or
        // set. [CompileTimeErrorCode.AMBIGUOUS_SET_OR_MAP_LITERAL_BOTH]
        // or [CompileTimeErrorCode.AMBIGUOUS_SET_OR_MAP_LITERAL_EITHER] is
        // already reported elsewhere.
        result.avoidReporting = true;
      }
      return result;
    } else {
      if (!node.isConst) {
        return InvalidConstant.forEntity(
            node, CompileTimeErrorCode.MISSING_CONST_IN_SET_LITERAL);
      }
      var nodeType = node.staticType;
      var elementType =
          nodeType is InterfaceType && nodeType.typeArguments.isNotEmpty
              ? nodeType.typeArguments[0]
              : _typeProvider.dynamicType;
      var setType = _typeProvider.setType(elementType);
      var set = <DartObjectImpl>{};
      return _buildSetConstant(set, node.elements, typeSystem, setType);
    }
  }

  @override
  Constant visitSimpleIdentifier(SimpleIdentifier node) {
    var value = _lexicalEnvironment?[node.name];
    if (value != null) {
      return _instantiateFunctionTypeForSimpleIdentifier(node, value);
    }

    return _getConstantValue(
      errorNode: node,
      expression: node,
      identifier: node,
      element: node.staticElement,
    );
  }

  @override
  Constant visitSimpleStringLiteral(SimpleStringLiteral node) {
    return DartObjectImpl(
      typeSystem,
      _typeProvider.stringType,
      StringState(node.value),
    );
  }

  @override
  Constant visitStringInterpolation(StringInterpolation node) {
    return _concatenateNodes(node, node.elements);
  }

  @override
  Constant visitSymbolLiteral(SymbolLiteral node) {
    StringBuffer buffer = StringBuffer();
    List<Token> components = node.components;
    for (int i = 0; i < components.length; i++) {
      if (i > 0) {
        buffer.writeCharCode(0x2E);
      }
      buffer.write(components[i].lexeme);
    }
    return DartObjectImpl(
      typeSystem,
      _typeProvider.symbolType,
      SymbolState(buffer.toString()),
    );
  }

  @override
  Constant visitTypeLiteral(TypeLiteral node) => evaluateConstant(node.type);

  /// Builds a list constant by adding the evaluated entries of [elements] to
  /// the given [list].
  ///
  /// The [typeSystem], [listType], and [elementType] are used to create a valid
  /// constant. We return an [InvalidConstant] if the evaluation of any of the
  /// elements failed.
  Constant _buildListConstant(
    List<DartObjectImpl> list,
    List<CollectionElement> elements,
    TypeSystemImpl typeSystem,
    DartType listType,
    DartType elementType,
  ) {
    for (var element in elements) {
      switch (element) {
        case Expression():
          var expression = evaluateConstant(element);
          switch (expression) {
            case InvalidConstant():
              return expression;
            case DartObjectImpl():
              list.add(expression);
          }
        case ForElement():
          return InvalidConstant.forEntity(
              element, CompileTimeErrorCode.CONST_EVAL_FOR_ELEMENT);
        case IfElement():
          var condition = evaluateConstant(element.expression);
          switch (condition) {
            case InvalidConstant():
              return condition;
            case DartObjectImpl():
              // If the condition is unknown, we mark this list as unknown.
              if (condition.isUnknown) {
                return DartObjectImpl.validWithUnknownValue(
                  typeSystem,
                  listType,
                  listElementType: elementType,
                );
              }
              var conditionValue = condition.toBoolValue();
              Constant? branchResult;
              if (conditionValue == null) {
                return InvalidConstant.forEntity(element.expression,
                    CompileTimeErrorCode.NON_BOOL_CONDITION);
              } else if (conditionValue) {
                branchResult = _buildListConstant(
                  list,
                  [element.thenElement],
                  typeSystem,
                  listType,
                  elementType,
                );
              } else if (element.elseElement != null) {
                branchResult = _buildListConstant(
                  list,
                  [element.elseElement!],
                  typeSystem,
                  listType,
                  elementType,
                );
              }
              if (branchResult is InvalidConstant) {
                return branchResult;
              }
          }
        case MapLiteralEntry():
          return InvalidConstant.forEntity(
              element, CompileTimeErrorCode.MAP_ENTRY_NOT_IN_MAP);
        case SpreadElement():
          var spread = evaluateConstant(element.expression);
          switch (spread) {
            case InvalidConstant():
              return spread;
            case DartObjectImpl():
              // Special case for ...?
              if (spread.isNull && element.isNullAware) {
                continue;
              }
              var listValue = spread.toListValue() ?? spread.toSetValue();
              if (listValue == null) {
                return InvalidConstant.forEntity(element.expression,
                    CompileTimeErrorCode.CONST_SPREAD_EXPECTED_LIST_OR_SET);
              }
              list.addAll(listValue);
          }
        case NullAwareElement():
          var value = evaluateConstant(element.value);
          switch (value) {
            case InvalidConstant():
              return value;
            case DartObjectImpl():
              if (value.isNull) {
                continue;
              }
              var result = _buildListConstant(
                list,
                [element.value],
                typeSystem,
                listType,
                elementType,
              );
              return result;
          }
      }
    }

    return DartObjectImpl(
      typeSystem,
      listType,
      ListState(
        elementType: elementType,
        elements: list,
      ),
    );
  }

  /// Builds a map constant by adding the evaluated entries of [elements] to
  /// the given [map].
  ///
  /// The [typeSystem] and [mapType] are used to create a valid map constant.
  /// We return an [InvalidConstant] if the evaluation of any of the elements
  /// failed.
  Constant _buildMapConstant(
      Map<DartObjectImpl, DartObjectImpl> map,
      List<CollectionElement> elements,
      TypeSystemImpl typeSystem,
      DartType mapType) {
    for (var element in elements) {
      switch (element) {
        case Expression():
          return InvalidConstant.forEntity(
              element, CompileTimeErrorCode.EXPRESSION_IN_MAP);
        case ForElement():
          return InvalidConstant.forEntity(
              element, CompileTimeErrorCode.CONST_EVAL_FOR_ELEMENT);
        case IfElement():
          var condition = evaluateConstant(element.expression);
          switch (condition) {
            case InvalidConstant():
              return condition;
            case DartObjectImpl():
              // If the condition is unknown, we mark this map as unknown.
              if (condition.isUnknown) {
                return DartObjectImpl.validWithUnknownValue(
                    typeSystem, mapType);
              }
              Constant? branchResult;
              var conditionValue = condition.toBoolValue();
              if (conditionValue == null) {
                return InvalidConstant.forEntity(element.expression,
                    CompileTimeErrorCode.NON_BOOL_CONDITION);
              } else if (conditionValue) {
                branchResult = _buildMapConstant(
                    map, [element.thenElement], typeSystem, mapType);
              } else if (element.elseElement != null) {
                branchResult = _buildMapConstant(
                    map, [element.elseElement!], typeSystem, mapType);
              }
              if (branchResult is InvalidConstant) {
                return branchResult;
              }
          }
        case MapLiteralEntry():
          var keyResult = evaluateConstant(element.key);
          var valueResult = evaluateConstant(element.value);
          switch (keyResult) {
            case InvalidConstant():
              return keyResult;
            case DartObjectImpl():
              switch (valueResult) {
                case InvalidConstant():
                  return valueResult;
                case DartObjectImpl():
                  map[keyResult] = valueResult;
              }
          }
        case SpreadElement():
          var spread = evaluateConstant(element.expression);
          switch (spread) {
            case InvalidConstant():
              return spread;
            case DartObjectImpl():
              // Special case for ...?
              if (spread.isNull && element.isNullAware) {
                continue;
              }
              var mapValue = spread.toMapValue();
              if (mapValue == null) {
                return InvalidConstant.forEntity(element.expression,
                    CompileTimeErrorCode.CONST_SPREAD_EXPECTED_MAP);
              }
              map.addAll(mapValue);
          }
        case NullAwareElement():
          // TODO(cstefantsova): Should it rather be its own code, for example,
          // `CompileTimeErrorCode.NULL_AWARE_ELEMENT_IN_MAP`?
          return InvalidConstant.forEntity(
              element, CompileTimeErrorCode.EXPRESSION_IN_MAP);
      }
    }

    return DartObjectImpl(typeSystem, mapType, MapState(map));
  }

  /// Builds a set constant by adding the evaluated entries of [elements] to
  /// the given [set].
  ///
  /// The [typeSystem] and [setType] are used to create a valid set constant.
  /// We return an [InvalidConstant] if the evaluation of any of the elements
  /// failed.
  Constant _buildSetConstant(
      Set<DartObjectImpl> set,
      List<CollectionElement> elements,
      TypeSystemImpl typeSystem,
      DartType setType) {
    for (var element in elements) {
      switch (element) {
        case Expression():
          var expression = evaluateConstant(element);
          switch (expression) {
            case InvalidConstant():
              return expression;
            case DartObjectImpl():
              set.add(expression);
          }
        case ForElement():
          return InvalidConstant.forEntity(
              element, CompileTimeErrorCode.CONST_EVAL_FOR_ELEMENT);
        case IfElement():
          var condition = evaluateConstant(element.expression);
          switch (condition) {
            case InvalidConstant():
              return condition;
            case DartObjectImpl():
              // If the condition is unknown, we mark this set as unknown.
              if (condition.isUnknown) {
                return DartObjectImpl.validWithUnknownValue(
                    typeSystem, setType);
              }
              Constant? branchResult;
              var conditionValue = condition.toBoolValue();
              if (conditionValue == null) {
                return InvalidConstant.forEntity(element.expression,
                    CompileTimeErrorCode.NON_BOOL_CONDITION);
              } else if (conditionValue) {
                branchResult = _buildSetConstant(
                    set, [element.thenElement], typeSystem, setType);
              } else if (element.elseElement != null) {
                branchResult = _buildSetConstant(
                    set, [element.elseElement!], typeSystem, setType);
              }
              if (branchResult is InvalidConstant) {
                return branchResult;
              }
          }
        case MapLiteralEntry():
          return InvalidConstant.forEntity(
              element, CompileTimeErrorCode.MAP_ENTRY_NOT_IN_MAP);
        case SpreadElement():
          var spread = evaluateConstant(element.expression);
          switch (spread) {
            case InvalidConstant():
              return spread;
            case DartObjectImpl():
              // Special case for ...?
              if (spread.isNull && element.isNullAware) {
                continue;
              }
              var setValue = spread.toSetValue() ?? spread.toListValue();
              if (setValue == null) {
                return InvalidConstant.forEntity(element.expression,
                    CompileTimeErrorCode.CONST_SPREAD_EXPECTED_LIST_OR_SET);
              }
              set.addAll(setValue);
          }
        case NullAwareElement():
          var value = evaluateConstant(element.value);
          switch (value) {
            case InvalidConstant():
              return value;
            case DartObjectImpl():
              if (value.isNull) {
                continue;
              }
              var result =
                  _buildSetConstant(set, [element.value], typeSystem, setType);
              return result;
          }
      }
    }

    return DartObjectImpl(typeSystem, setType, SetState(set));
  }

  /// Returns the result of concatenating [astNodes].
  ///
  /// If there's an [InvalidConstant] found, it will return early.
  Constant _concatenateNodes(Expression node, List<AstNode> astNodes) {
    Constant? result;
    for (AstNode astNode in astNodes) {
      var constant = evaluateConstant(astNode);
      if (constant is! DartObjectImpl) {
        return constant;
      }

      if (result == null) {
        result = constant;
      } else if (result is DartObjectImpl) {
        result = _dartObjectComputer.concatenate(node, result, constant);
        if (result is InvalidConstant) {
          return result;
        }
      }
    }

    if (result == null) {
      // No errors have been detected, but we did not concatenate any nodes.
      return DartObjectImpl(
        typeSystem,
        _typeProvider.stringType,
        StringState.UNKNOWN_VALUE,
      );
    }
    return result;
  }

  /// Attempt to evaluate a constant property access.
  ///
  /// Return a valid [DartObjectImpl] if the given [targetResult] represents a
  /// `String` and the [identifier] is `length`, an [InvalidConstant] if there's
  /// an error, and `null` otherwise.
  Constant? _evaluatePropertyAccess(DartObjectImpl targetResult,
      SimpleIdentifier identifier, AstNode errorNode) {
    var propertyElement = identifier.staticElement;
    if (propertyElement is PropertyAccessorElement &&
        propertyElement.isGetter &&
        propertyElement.isStatic) {
      return null;
    }

    var propertyContainer = propertyElement?.enclosingElement;
    switch (propertyContainer) {
      case ExtensionElement():
        return InvalidConstant.forEntity(
          errorNode,
          CompileTimeErrorCode.CONST_EVAL_EXTENSION_METHOD,
        );
      case ExtensionTypeElement():
        return InvalidConstant.forEntity(
          errorNode,
          CompileTimeErrorCode.CONST_EVAL_EXTENSION_TYPE_METHOD,
        );
    }

    var targetType = targetResult.type;

    // Evaluate a constant that reads the length of a `String`.
    if (identifier.name == 'length' &&
        targetType is InterfaceType &&
        targetType.isDartCoreString) {
      return _dartObjectComputer.stringLength(errorNode, targetResult);
    }

    var element = identifier.staticElement;
    if (element != null && element is ExecutableElement && element.isStatic) {
      return null;
    }

    // No other property access is allowed except for `.length` of a `String`.
    return InvalidConstant.forEntity(
        errorNode, CompileTimeErrorCode.CONST_EVAL_PROPERTY_ACCESS,
        arguments: [identifier.name, targetType.getDisplayString()]);
  }

  /// Returns a [Constant] based on the [element] provided.
  ///
  /// The [errorNode] is the node to be used if an error needs to be reported,
  /// the [expression] is used to identify type parameter errors, and
  /// [identifier] to determine the constant of any [ExecutableElement]s.
  ///
  // TODO(kallentu): Revisit this method and clean it up a bit.
  Constant _getConstantValue({
    required AstNode errorNode,
    required Expression? expression,
    required SimpleIdentifier? identifier,
    required Element? element,
    DartType? givenType,
  }) {
    var errorNode2 = _evaluationEngine.configuration.errorNode(errorNode);
    element = element?.declaration;

    var variableElement =
        element is PropertyAccessorElement ? element.variable2 : element;

    // TODO(srawlins): Remove this check when [FunctionReference]s are inserted
    // for generic function instantiation for pre-constructor-references code.
    if (expression is SimpleIdentifier &&
        (expression.tearOffTypeArgumentTypes?.any(hasTypeParameterReference) ??
            false)) {
      return InvalidConstant.forEntity(
          expression, CompileTimeErrorCode.CONST_TYPE_PARAMETER);
    }

    if (variableElement is VariableElementImpl) {
      // We access values of constant variables here in two cases: when we
      // compute values of other constant variables, or when we compute values
      // and errors for other constant expressions. In either case we have
      // already computed values of all dependencies first (or detect a cycle),
      // so the value has already been computed and we can just return it.
      var evaluationResult = variableElement.evaluationResult;
      if (variableElement.isConst) {
        switch (evaluationResult) {
          case null:
            // The constant value isn't computed yet, or there is an error while
            // computing. We will mark it and determine whether or not to
            // continue the evaluation upstream.
            return InvalidConstant.genericError(errorNode, isUnresolved: true);
          case DartObjectImpl():
            if (identifier == null) {
              return InvalidConstant.forEntity(
                  errorNode, CompileTimeErrorCode.INVALID_CONSTANT);
            }
            return _instantiateFunctionTypeForSimpleIdentifier(
                identifier, evaluationResult);
          case InvalidConstant():
            // TODO(kallentu): Investigate and fix the test failures that occur
            // if we remove `avoidReporting`.
            return InvalidConstant.forEntity(
                errorNode, CompileTimeErrorCode.INVALID_CONSTANT,
                isUnresolved: true, avoidReporting: true);
        }
      }
    } else if (variableElement is ConstructorElementImpl &&
        expression != null) {
      return DartObjectImpl(
        typeSystem,
        expression.typeOrThrow,
        FunctionState(variableElement),
      );
    } else if (variableElement is ExecutableElementImpl) {
      if (variableElement.isStatic) {
        var rawType = DartObjectImpl(
          typeSystem,
          variableElement.type,
          FunctionState(variableElement),
        );
        if (identifier == null) {
          return InvalidConstant.forEntity(
              errorNode, CompileTimeErrorCode.INVALID_CONSTANT);
        }
        return _instantiateFunctionTypeForSimpleIdentifier(identifier, rawType);
      }
    } else if (variableElement is InterfaceElement) {
      var type = givenType ??
          variableElement.instantiate(
            typeArguments: variableElement.typeParameters
                .map((t) => _typeProvider.dynamicType)
                .toFixedList(),
            nullabilitySuffix: NullabilitySuffix.none,
          );
      return DartObjectImpl(
        typeSystem,
        _typeProvider.typeType,
        TypeState(type),
      );
    } else if (variableElement is DynamicElementImpl) {
      return DartObjectImpl(
        typeSystem,
        _typeProvider.typeType,
        TypeState(_typeProvider.dynamicType),
      );
    } else if (variableElement is TypeAliasElement) {
      var type = givenType ??
          variableElement.instantiate(
            typeArguments: variableElement.typeParameters
                .map((t) => t.bound ?? _typeProvider.dynamicType)
                .toList(),
            nullabilitySuffix: NullabilitySuffix.none,
          );
      return DartObjectImpl(
        typeSystem,
        _typeProvider.typeType,
        TypeState(type),
      );
    } else if (variableElement is NeverElementImpl) {
      return DartObjectImpl(
        typeSystem,
        _typeProvider.typeType,
        TypeState(_typeProvider.neverType),
      );
    } else if (variableElement is TypeParameterElement) {
      // Constants may refer to type parameters only if the constructor-tearoffs
      // feature is enabled.
      if (_library.featureSet.isEnabled(Feature.constructor_tearoffs)) {
        var typeArgument = _lexicalTypeEnvironment?[variableElement];
        if (typeArgument != null) {
          return DartObjectImpl(
            typeSystem,
            _typeProvider.typeType,
            TypeState(typeArgument),
          );
        }
        return InvalidConstant.forEntity(
            errorNode2, CompileTimeErrorCode.CONST_TYPE_PARAMETER);
      }
    }

    // The expression is unresolved by the time we are evaluating it. We'll mark
    // it and return immediately.
    if (expression != null && expression.staticType is InvalidType) {
      return InvalidConstant.genericError(errorNode, isUnresolved: true);
    }

    // TODO(srawlins): Use a specific error code.
    // https://github.com/dart-lang/sdk/issues/47061
    return InvalidConstant.genericError(errorNode2);
  }

  /// Returns the appropriate error for accessing an element in a deferred
  /// library.
  ///
  /// If no specific error can be chosen, an [InvalidConstant] error using
  /// [CompileTimeErrorCode.INVALID_CONSTANT] is returned.
  InvalidConstant _getDeferredLibraryError(
      AstNode node, SyntacticEntity errorTarget) {
    var errorCode = () {
      AstNode? previous;
      for (AstNode? current = node; current != null;) {
        if (current is Annotation) {
          return CompileTimeErrorCode
              .INVALID_ANNOTATION_CONSTANT_VALUE_FROM_DEFERRED_LIBRARY;
        } else if (current is ConstantContextForExpressionImpl) {
          return CompileTimeErrorCode
              .CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE_FROM_DEFERRED_LIBRARY;
        } else if (current is DefaultFormalParameter) {
          return CompileTimeErrorCode
              .NON_CONSTANT_DEFAULT_VALUE_FROM_DEFERRED_LIBRARY;
        } else if (current is IfElement && current.expression == node) {
          return CompileTimeErrorCode
              .IF_ELEMENT_CONDITION_FROM_DEFERRED_LIBRARY;
        } else if (current is InstanceCreationExpression) {
          return CompileTimeErrorCode
              .CONST_CONSTRUCTOR_CONSTANT_FROM_DEFERRED_LIBRARY;
        } else if (current is ListLiteral) {
          return CompileTimeErrorCode
              .NON_CONSTANT_LIST_ELEMENT_FROM_DEFERRED_LIBRARY;
        } else if (current is MapLiteralEntry) {
          if (previous == current.key) {
            return CompileTimeErrorCode
                .NON_CONSTANT_MAP_KEY_FROM_DEFERRED_LIBRARY;
          } else {
            return CompileTimeErrorCode
                .NON_CONSTANT_MAP_VALUE_FROM_DEFERRED_LIBRARY;
          }
        } else if (current is RecordLiteral) {
          return CompileTimeErrorCode
              .NON_CONSTANT_RECORD_FIELD_FROM_DEFERRED_LIBRARY;
        } else if (current is SetOrMapLiteral) {
          return CompileTimeErrorCode.SET_ELEMENT_FROM_DEFERRED_LIBRARY;
        } else if (current is SpreadElement) {
          return CompileTimeErrorCode.SPREAD_EXPRESSION_FROM_DEFERRED_LIBRARY;
        } else if (current is SwitchCase) {
          return CompileTimeErrorCode
              .NON_CONSTANT_CASE_EXPRESSION_FROM_DEFERRED_LIBRARY;
        } else if (current is SwitchPatternCase) {
          return CompileTimeErrorCode.PATTERN_CONSTANT_FROM_DEFERRED_LIBRARY;
        } else if (current is VariableDeclaration) {
          return CompileTimeErrorCode
              .CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE_FROM_DEFERRED_LIBRARY;
        }
        previous = current;
        current = current.parent;
      }
    }();
    if (errorCode != null) {
      return InvalidConstant.forEntity(errorTarget, errorCode);
    }
    return InvalidConstant.forEntity(
        node, CompileTimeErrorCode.INVALID_CONSTANT);
  }

  /// If the type of [value] is a generic [FunctionType], and [node] has type
  /// argument types, returns [value] type-instantiated with those [node]'s
  /// type argument types, otherwise returns [value].
  DartObjectImpl _instantiateFunctionType(
      FunctionReference node, DartObjectImpl value) {
    var functionElement = value.toFunctionValue();
    if (functionElement is! ExecutableElement) {
      return value;
    }
    var valueType = functionElement.type;
    if (valueType.typeFormals.isNotEmpty) {
      var typeArgumentTypes = node.typeArgumentTypes;
      if (typeArgumentTypes != null && typeArgumentTypes.isNotEmpty) {
        var instantiatedType =
            functionElement.type.instantiate(typeArgumentTypes);
        var substitution = _substitution;
        if (substitution != null) {
          instantiatedType =
              substitution.substituteType(instantiatedType) as FunctionType;
        }
        return value.typeInstantiate(
            typeSystem, instantiatedType, typeArgumentTypes);
      }
    }
    return value;
  }

  /// If the type of [value] is a generic [FunctionType], and [node] is a
  /// [SimpleIdentifier] with tear-off type argument types, returns [value]
  /// type-instantiated with those [node]'s tear-off type argument types,
  /// otherwise returns [value].
  Constant _instantiateFunctionTypeForSimpleIdentifier(
      SimpleIdentifier node, DartObjectImpl value) {
    // TODO(srawlins): When all code uses [FunctionReference]s generated via
    // generic function instantiation, remove this method and all call sites.
    var functionElement = value.toFunctionValue();
    if (functionElement is! ExecutableElement) {
      return value;
    }
    var valueType = functionElement.type;
    if (valueType.typeFormals.isNotEmpty) {
      var tearOffTypeArgumentTypes = node.tearOffTypeArgumentTypes;
      if (tearOffTypeArgumentTypes != null &&
          tearOffTypeArgumentTypes.isNotEmpty) {
        var instantiatedType =
            functionElement.type.instantiate(tearOffTypeArgumentTypes);
        return value.typeInstantiate(
            typeSystem, instantiatedType, tearOffTypeArgumentTypes);
      }
    }
    return value;
  }

  /// Returns the first not-potentially constant error found with [node] or
  /// `null` if there are none.
  InvalidConstant? _reportNotPotentialConstants(AstNode node) {
    var notPotentiallyConstants = getNotPotentiallyConstants(
      node,
      featureSet: _library.featureSet,
    );
    if (notPotentiallyConstants.isEmpty) return null;

    // Only report the first invalid constant we see.
    return InvalidConstant.forEntity(
        notPotentiallyConstants.first, CompileTimeErrorCode.INVALID_CONSTANT);
  }

  /// Return the value of the given [expression], or a representation of a fake
  /// constant to continue the evaluation if the expression is unresolved.
  Constant _valueOf(Expression expression, DartType defaultType) {
    var expressionValue = evaluateConstant(expression);
    switch (expressionValue) {
      // TODO(kallentu): g3 relies on reporting errors found here, but also
      // being able to continue the evaluation with populating fields. Fix the
      // interaction with g3 more elegantly.
      case InvalidConstant(isUnresolved: true):
        if (!expressionValue.avoidReporting) {
          _errorReporter.atOffset(
            offset: expressionValue.offset,
            length: expressionValue.length,
            errorCode: expressionValue.errorCode,
            arguments: expressionValue.arguments,
            contextMessages: expressionValue.contextMessages,
          );
        }
        return ConstantEvaluationEngine._unresolvedObject(
            _library, defaultType);
      case Constant():
        return expressionValue;
    }
  }
}

/// A utility class that contains methods for manipulating instances of a Dart
/// class and for collecting errors during evaluation.
class DartObjectComputer {
  final TypeSystemImpl _typeSystem;
  final FeatureSet _featureSet;

  DartObjectComputer(this._typeSystem, this._featureSet);

  Constant add(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.add(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  /// Return the result of applying boolean conversion to the
  /// [evaluationResult]. The [node] is the node against which errors should be
  /// reported.
  Constant applyBooleanConversion(
      AstNode node, DartObjectImpl evaluationResult) {
    try {
      return evaluationResult.convertToBool(_typeSystem);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant bitNot(Expression node, DartObjectImpl evaluationResult) {
    try {
      return evaluationResult.bitNot(_typeSystem);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant castToType(
      AsExpression node, DartObjectImpl expression, DartObjectImpl type) {
    try {
      return expression.castToType(_typeSystem, type);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant concatenate(Expression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.concatenate(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant divide(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.divide(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant eagerAnd(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.eagerAnd(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant eagerOr(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.eagerOr(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant eagerXor(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.eagerXor(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant equalEqual(Expression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.equalEqual(_typeSystem, _featureSet, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant greaterThan(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.greaterThan(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant greaterThanOrEqual(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.greaterThanOrEqual(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant integerDivide(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.integerDivide(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(
        node,
        exception.errorCode,
        isRuntimeException: exception.isRuntimeException,
      );
    }
  }

  Constant isIdentical(Expression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.isIdentical2(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant lazyAnd(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl Function() rightOperandComputer) {
    try {
      return leftOperand.lazyAnd(_typeSystem, rightOperandComputer);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant lazyOr(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl Function() rightOperandComputer) {
    try {
      return leftOperand.lazyOr(_typeSystem, rightOperandComputer);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant lazyQuestionQuestion(Expression node, DartObjectImpl leftOperand,
      Constant Function() rightOperandComputer) {
    if (leftOperand.isNull) {
      return rightOperandComputer();
    }
    return leftOperand;
  }

  Constant lessThan(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.lessThan(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant lessThanOrEqual(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.lessThanOrEqual(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant logicalNot(Expression node, DartObjectImpl evaluationResult) {
    try {
      return evaluationResult.logicalNot(_typeSystem);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant logicalShiftRight(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.logicalShiftRight(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant minus(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.minus(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant negated(Expression node, DartObjectImpl evaluationResult) {
    try {
      return evaluationResult.negated(_typeSystem);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant notEqual(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.notEqual(_typeSystem, _featureSet, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant performToString(AstNode node, DartObjectImpl evaluationResult) {
    try {
      return evaluationResult.performToString(_typeSystem);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant remainder(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.remainder(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant shiftLeft(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.shiftLeft(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant shiftRight(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.shiftRight(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant stringLength(AstNode node, DartObjectImpl evaluationResult) {
    try {
      return evaluationResult.stringLength(_typeSystem);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant times(BinaryExpression node, DartObjectImpl leftOperand,
      DartObjectImpl rightOperand) {
    try {
      return leftOperand.times(_typeSystem, rightOperand);
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }

  Constant typeInstantiate(
    DartObjectImpl function,
    List<DartType> typeArguments,
    Expression node,
    TypeArgumentList typeArgumentsErrorNode,
  ) {
    var rawType = function.type;
    if (rawType is FunctionType) {
      if (typeArguments.length != rawType.typeFormals.length) {
        if (node is SimpleIdentifier) {
          return InvalidConstant.forEntity(typeArgumentsErrorNode,
              CompileTimeErrorCode.WRONG_NUMBER_OF_TYPE_ARGUMENTS_FUNCTION,
              arguments: [
                node.name,
                rawType.typeFormals.length,
                typeArguments.length
              ]);
        }
        return InvalidConstant.forEntity(
            typeArgumentsErrorNode,
            CompileTimeErrorCode
                .WRONG_NUMBER_OF_TYPE_ARGUMENTS_ANONYMOUS_FUNCTION,
            arguments: [rawType.typeFormals.length, typeArguments.length]);
      }
      var type = rawType.instantiate(typeArguments);
      return function.typeInstantiate(_typeSystem, type, typeArguments);
    } else {
      return InvalidConstant.forEntity(
          node, CompileTimeErrorCode.INVALID_CONSTANT);
    }
  }

  Constant typeTest(
      IsExpression node, DartObjectImpl expression, DartObjectImpl type) {
    try {
      DartObjectImpl result = expression.hasType(_typeSystem, type);
      if (node.notOperator != null) {
        return result.logicalNot(_typeSystem);
      }
      return result;
    } on EvaluationException catch (exception) {
      return InvalidConstant.forEntity(node, exception.errorCode);
    }
  }
}

class _EnumConstant {
  final int index;
  final String name;

  _EnumConstant({
    required this.index,
    required this.name,
  });
}

/// The result of evaluation the initializers declared on a const constructor.
class _InitializersEvaluationResult {
  /// The result of a const evaluation of an initializer.
  ///
  /// If the evaluation of the const instance creation expression is incomplete,
  /// then [result] will be `null`.
  ///
  /// If a redirecting initializer which redirects to a const constructor was
  /// encountered, [result] is the result of evaluating that call.
  ///
  /// If an assert initializer is encountered, and the evaluation of this assert
  /// results in an error or a `false` value, [result] is an [InvalidConstant].
  final Constant? result;

  /// Whether evaluation of the const instance creation expression which led to
  /// evaluating constructor initializers is complete.
  ///
  /// If `true`, `result` should be used as the result of said const instance
  /// creation expression evaluation.
  final bool evaluationIsComplete;

  /// If a superinitializer was encountered, the name of the super constructor,
  /// otherwise `null`.
  final String? superName;

  /// If a superinitializer was encountered, the arguments passed to the super
  /// constructor, otherwise `null`.
  final List<Expression>? superArguments;

  _InitializersEvaluationResult(
    this.result, {
    required this.evaluationIsComplete,
    this.superName,
    this.superArguments,
  });
}

/// An evaluator which evaluates a const instance creation expression.
///
/// [_InstanceCreationEvaluator.evaluate] is the main entrypoint.
class _InstanceCreationEvaluator {
  /// Parameter to "fromEnvironment" methods that denotes the default value.
  static const String _defaultValueParam = 'defaultValue';

  final ConstantEvaluationEngine _evaluationEngine;

  /// The set of variables declared on the command line using '-D'.
  final DeclaredVariables _declaredVariables;

  final LibraryElementImpl _library;

  final BooleanErrorListener _externalErrorListener = BooleanErrorListener();

  /// An error reporter for errors determined while computing values for field
  /// initializers, or default values for the constructor parameters.
  ///
  /// Such errors cannot be reported into [_errorReporter], because they usually
  /// happen in a different source. But they still should cause a constant
  /// evaluation error for the current node.
  late final ErrorReporter _externalErrorReporter = ErrorReporter(
    _externalErrorListener,
    _constructor.source,
  );

  late final ConstantVisitor _initializerVisitor = ConstantVisitor(
    _evaluationEngine,
    _constructor.library as LibraryElementImpl,
    _externalErrorReporter,
    lexicalEnvironment: _parameterMap,
    lexicalTypeEnvironment: _typeParameterMap,
    substitution: Substitution.fromInterfaceType(definingType),
  );

  /// The node used for most error reporting.
  final AstNode _errorNode;

  final ConstructorElement _constructor;

  final List<DartType>? _typeArguments;

  final ConstructorInvocation _invocation;

  final Map<String, NamedExpression> _namedNodes;

  final Map<String, DartObjectImpl> _namedValues;

  final List<DartObjectImpl> _argumentValues;

  final Map<TypeParameterElement, DartType> _typeParameterMap = HashMap();

  final Map<String, DartObjectImpl> _parameterMap = HashMap();

  final Map<String, DartObjectImpl> _fieldMap = HashMap();

  /// Constructor for [_InstanceCreationEvaluator].
  ///
  /// This constructor is private, as the entry point for using a
  /// [_InstanceCreationEvaluator] is the static method,
  /// [_InstanceCreationEvaluator.evaluate].
  _InstanceCreationEvaluator._(
    this._evaluationEngine,
    this._declaredVariables,
    this._library,
    this._errorNode,
    this._constructor,
    this._typeArguments, {
    required Map<String, NamedExpression> namedNodes,
    required Map<String, DartObjectImpl> namedValues,
    required List<DartObjectImpl> argumentValues,
    required ConstructorInvocation invocation,
  })  : _namedNodes = namedNodes,
        _namedValues = namedValues,
        _argumentValues = argumentValues,
        _invocation = invocation;

  InterfaceType get definingType => _constructor.returnType;

  DartObjectImpl? get firstArgument => _argumentValues[0];

  TypeProvider get typeProvider => _library.typeProvider;

  TypeSystemImpl get typeSystem => _library.typeSystem;

  /// Evaluates this constructor call as a factory constructor call.
  Constant evaluateFactoryConstructorCall(List<Expression> arguments) {
    var definingClass = _constructor.enclosingElement;
    var argumentCount = arguments.length;
    if (_constructor.name == "fromEnvironment") {
      if (!_checkFromEnvironmentArguments(arguments, definingType)) {
        return InvalidConstant.forEntity(
            _errorNode, CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
      }
      String? variableName =
          argumentCount < 1 ? null : firstArgument?.toStringValue();
      if (definingClass == typeProvider.boolElement) {
        // Special case: https://github.com/dart-lang/sdk/issues/50045
        if (variableName == 'dart.library.js_util') {
          return DartObjectImpl(
            typeSystem,
            typeProvider.boolType,
            BoolState.UNKNOWN_VALUE,
          );
        }
        return FromEnvironmentEvaluator(typeSystem, _declaredVariables)
            .getBool2(variableName, _namedValues, _constructor);
      } else if (definingClass == typeProvider.intElement) {
        return FromEnvironmentEvaluator(typeSystem, _declaredVariables)
            .getInt2(variableName, _namedValues, _constructor);
      } else if (definingClass == typeProvider.stringElement) {
        return FromEnvironmentEvaluator(typeSystem, _declaredVariables)
            .getString2(variableName, _namedValues, _constructor);
      }
    } else if (_constructor.name == 'hasEnvironment' &&
        definingClass == typeProvider.boolElement) {
      var name = argumentCount < 1 ? null : firstArgument?.toStringValue();
      return FromEnvironmentEvaluator(typeSystem, _declaredVariables)
          .hasEnvironment(name);
    } else if (_constructor.name == "" &&
        definingClass == typeProvider.symbolElement &&
        argumentCount == 1) {
      if (!_checkSymbolArguments(arguments)) {
        return InvalidConstant.forEntity(
            _errorNode, CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
      }
      return DartObjectImpl(
        typeSystem,
        definingType,
        SymbolState(firstArgument?.toStringValue()),
      );
    }
    // Either it's an external const factory constructor that we can't
    // emulate, or an error occurred (a cycle, or a const constructor trying to
    // delegate to a non-const constructor).
    //
    // In the former case, the best we can do is consider it an unknown value.
    // In the latter case, the error has already been reported, so considering
    // it an unknown value will suppress further errors.
    return DartObjectImpl.validWithUnknownValue(typeSystem, definingType);
  }

  Constant evaluateGenerativeConstructorCall(List<Expression> arguments) {
    InvalidConstant? error;

    // Start with final fields that are initialized at their declaration site.
    error = _checkFields();
    if (error != null) {
      return error;
    }

    _checkTypeParameters();

    error = _checkParameters(arguments);
    if (error != null) {
      return error;
    }

    var evaluationResult = _checkInitializers();
    var result = evaluationResult.result;
    if (result != null && evaluationResult.evaluationIsComplete) {
      return result;
    }

    error = _checkSuperConstructorCall(
        superName: evaluationResult.superName,
        superArguments: evaluationResult.superArguments);
    if (error != null) {
      return error;
    }

    var definingType = this.definingType;
    if (definingType.element case ExtensionTypeElement element) {
      var representation = _fieldMap[element.representation.name];
      if (representation != null) {
        return representation;
      }
    }

    return DartObjectImpl(
      typeSystem,
      definingType,
      GenericState(_fieldMap, invocation: _invocation),
    );
  }

  void _addImplicitArgumentsFromSuperFormals(List<Expression> superArguments) {
    var positionalIndex = 0;
    for (var parameter in _constructor.parameters) {
      if (parameter is SuperFormalParameterElement) {
        var value = SimpleIdentifierImpl(
          StringToken(TokenType.STRING, parameter.name, -1),
        )
          ..staticElement = parameter
          ..setPseudoExpressionStaticType(parameter.type);
        if (parameter.isPositional) {
          superArguments.insert(positionalIndex++, value);
        } else {
          superArguments.add(
            NamedExpressionImpl(
              name: LabelImpl(
                label: SimpleIdentifierImpl(
                  StringToken(TokenType.STRING, parameter.name, -1),
                )..staticElement = parameter,
                colon: StringToken(TokenType.COLON, ':', -1),
              ),
              expression: value,
            )..setPseudoExpressionStaticType(value.typeOrThrow),
          );
        }
      }
    }
  }

  /// Checks for any errors in the fields of [_constructor].
  ///
  /// Returns an [InvalidConstant] if one is found, or `null` otherwise.
  InvalidConstant? _checkFields() {
    var fields = _constructor.enclosingElement.fields;
    for (var field in fields) {
      if ((field.isFinal || field.isConst) &&
          !field.isStatic &&
          field is ConstFieldElementImpl) {
        var fieldValue = field.evaluationResult;

        // It is possible that the evaluation result is null.
        // This happens for example when we have duplicate fields.
        // `class Test {final x = 1; final x = 2; const Test();}`
        if (fieldValue == null || fieldValue is! DartObjectImpl) {
          continue;
        }
        // Match the value and the type.
        var fieldType = FieldMember.from(field, _constructor.returnType).type;
        if (!typeSystem.runtimeTypeMatch(fieldValue, fieldType)) {
          var isRuntimeException = hasTypeParameterReference(field.type);
          var errorNode = field.constantInitializer ?? _errorNode;
          return InvalidConstant.forEntity(errorNode,
              CompileTimeErrorCode.CONST_CONSTRUCTOR_FIELD_TYPE_MISMATCH,
              arguments: [
                fieldValue.type.getDisplayString(),
                field.name,
                fieldType.getDisplayString(),
              ],
              isRuntimeException: isRuntimeException);
        }
        _fieldMap[field.name] = fieldValue;
      }
    }
    return null;
  }

  /// Check that the arguments to a call to `fromEnvironment()` are correct.
  ///
  /// The [arguments] are the AST nodes of the arguments. The [argumentValues]
  /// are the values of the unnamed arguments. The [namedArgumentValues] are the
  /// values of the named arguments. The [expectedDefaultValueType] is the
  /// allowed type of the "defaultValue" parameter (if present). Note:
  /// "defaultValue" is always allowed to be `null`. Return `true` if the
  /// arguments are correct, `false` otherwise.
  bool _checkFromEnvironmentArguments(
    List<Expression> arguments,
    InterfaceType expectedDefaultValueType,
  ) {
    var argumentCount = arguments.length;
    if (argumentCount < 1 || argumentCount > 2) {
      return false;
    }
    if (arguments[0] is NamedExpression) {
      return false;
    }
    if (firstArgument!.type != typeProvider.stringType) {
      return false;
    }
    if (argumentCount == 2) {
      var secondArgument = arguments[1];
      if (secondArgument is NamedExpression) {
        if (!(secondArgument.name.label.name == _defaultValueParam)) {
          return false;
        }
        var defaultValueType = _namedValues[_defaultValueParam]!.type;
        if (!(defaultValueType == expectedDefaultValueType ||
            defaultValueType == typeProvider.nullType)) {
          return false;
        }
      } else {
        return false;
      }
    }
    return true;
  }

  /// Checks for any errors in the constant initializers of [_constructor].
  ///
  /// Returns an [_InitializersEvaluationResult] which contain a result from a
  /// redirecting constructor invocation, an [InvalidConstant], or an
  /// incomplete state for further evaluation.
  _InitializersEvaluationResult _checkInitializers() {
    var constructorBase = _constructor.declaration as ConstructorElementImpl;
    // If we encounter a superinitializer, store the name of the constructor,
    // and the arguments.
    String? superName;
    List<Expression>? superArguments;
    for (var initializer in constructorBase.constantInitializers) {
      if (initializer is ConstructorFieldInitializer) {
        var initializerExpression = initializer.expression;
        var evaluationResult =
            _initializerVisitor.evaluateConstant(initializerExpression);
        switch (evaluationResult) {
          case DartObjectImpl():
            var fieldName = initializer.fieldName.name;
            if (_fieldMap.containsKey(fieldName)) {
              return _InitializersEvaluationResult(
                  InvalidConstant.forEntity(_errorNode,
                      CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION),
                  evaluationIsComplete: true);
            }
            _fieldMap[fieldName] = evaluationResult;
            var getter = definingType.getGetter(fieldName);
            if (getter != null) {
              var field = getter.variable2;
              if (field == null) {
                return _InitializersEvaluationResult(
                  InvalidConstant.forElement(
                    getter,
                    CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION,
                  ),
                  evaluationIsComplete: true,
                );
              }
              if (!typeSystem.runtimeTypeMatch(evaluationResult, field.type)) {
                // Mark the type mismatch error as a runtime exception if the
                // initializer is statically assignable to the field.
                // TODO(kallentu): https://github.com/dart-lang/sdk/issues/53263
                var isRuntimeException = _library.typeSystem.isAssignableTo(
                  initializerExpression.typeOrThrow,
                  field.type,
                );
                var errorNode =
                    isRuntimeException ? initializerExpression : _errorNode;
                return _InitializersEvaluationResult(
                    InvalidConstant.forEntity(
                        errorNode,
                        CompileTimeErrorCode
                            .CONST_CONSTRUCTOR_FIELD_TYPE_MISMATCH,
                        arguments: [
                          evaluationResult.type.getDisplayString(),
                          fieldName,
                          field.type.getDisplayString(),
                        ],
                        isRuntimeException: isRuntimeException),
                    evaluationIsComplete: true);
              }
            }
          case InvalidConstant(isRuntimeException: false):
            // Add additional information to the error in the field initializer
            // because the error is reported at the location of [_errorNode].
            if (evaluationResult.contextMessages.isEmpty) {
              evaluationResult.contextMessages.add(DiagnosticMessageImpl(
                filePath: _constructor.source.fullName,
                length: evaluationResult.length,
                message: "The error is in the field initializer of "
                    "'${_constructor.displayName}', and occurs here.",
                offset: evaluationResult.offset,
                url: null,
              ));
            }
            return _InitializersEvaluationResult(
                InvalidConstant.copyWithEntity(evaluationResult, _errorNode),
                evaluationIsComplete: true);
          case InvalidConstant():
            return _InitializersEvaluationResult(evaluationResult,
                evaluationIsComplete: true);
        }
      } else if (initializer is SuperConstructorInvocation) {
        var name = initializer.constructorName;
        if (name != null) {
          superName = name.name;
        }
        superArguments = initializer.argumentList.arguments.toList();
        _addImplicitArgumentsFromSuperFormals(superArguments);
      } else if (initializer is RedirectingConstructorInvocation) {
        // This is a redirecting constructor, so just evaluate the constructor
        // it redirects to.
        var constructor = initializer.staticElement;
        if (constructor != null && constructor.isConst) {
          // Instantiate the constructor with the in-scope type arguments.
          constructor = ConstructorMember.from(constructor, definingType);
          var result = _evaluationEngine.evaluateConstructorCall(
              _library,
              _errorNode,
              _typeArguments,
              initializer.argumentList.arguments,
              constructor,
              _initializerVisitor,
              invocation: _invocation);
          return _InitializersEvaluationResult(result,
              evaluationIsComplete: true);
        }
      } else if (initializer is AssertInitializer) {
        var condition = initializer.condition;
        var evaluationResult = _initializerVisitor.evaluateConstant(condition);
        switch (evaluationResult) {
          case DartObjectImpl():
            if (!evaluationResult.isBool ||
                evaluationResult.toBoolValue() == false) {
              InvalidConstant? invalidConstant;

              // Adds the assert message if we are able to evaluate it.
              if (initializer.message case var message?) {
                var messageConstant =
                    _initializerVisitor.evaluateConstant(message);
                if (messageConstant is DartObjectImpl) {
                  if (messageConstant.toStringValue() case var assertMessage?) {
                    invalidConstant = InvalidConstant.forEntity(
                        initializer,
                        CompileTimeErrorCode
                            .CONST_EVAL_ASSERTION_FAILURE_WITH_MESSAGE,
                        arguments: [assertMessage],
                        isRuntimeException: true);
                  }
                }
              }

              invalidConstant ??= InvalidConstant.forEntity(initializer,
                  CompileTimeErrorCode.CONST_EVAL_ASSERTION_FAILURE,
                  isRuntimeException: true);
              return _InitializersEvaluationResult(
                invalidConstant,
                evaluationIsComplete: true,
              );
            }
          case InvalidConstant(isRuntimeException: false):
            // Add additional information to the error in the assert initializer
            // because the error is reported at the location of [_errorNode].
            if (evaluationResult.contextMessages.isEmpty) {
              evaluationResult.contextMessages.add(DiagnosticMessageImpl(
                filePath: _constructor.source.fullName,
                length: evaluationResult.length,
                message: "The error is in the assert initializer of "
                    "'${_constructor.displayName}', and occurs here.",
                offset: evaluationResult.offset,
                url: null,
              ));
            }
            return _InitializersEvaluationResult(
                InvalidConstant.copyWithEntity(evaluationResult, _errorNode),
                evaluationIsComplete: true);
          case InvalidConstant():
            return _InitializersEvaluationResult(evaluationResult,
                evaluationIsComplete: true);
        }
      }
    }

    if (definingType.superclass != null && superArguments == null) {
      superArguments = [];
      _addImplicitArgumentsFromSuperFormals(superArguments);
    }

    return _InitializersEvaluationResult(null,
        evaluationIsComplete: false,
        superName: superName,
        superArguments: superArguments);
  }

  /// Checks for any errors in the parameters of [_constructor].
  ///
  /// Returns an [InvalidConstant] if one is found, or `null` otherwise.
  InvalidConstant? _checkParameters(List<Expression> arguments) {
    var parameters = _constructor.parameters;
    var parameterCount = parameters.length;

    for (var i = 0; i < parameterCount; i++) {
      var parameter = parameters[i];
      var baseParameter = parameter.declaration;
      DartObjectImpl? argumentValue;
      AstNode? errorTarget;
      if (baseParameter.isNamed) {
        argumentValue = _namedValues[baseParameter.name];
        errorTarget = _namedNodes[baseParameter.name];
      } else if (i < _argumentValues.length) {
        argumentValue = _argumentValues[i];
        errorTarget = arguments[i];
      }
      // No argument node that we can direct error messages to, because we
      // are handling an optional parameter that wasn't specified.  So just
      // direct error messages to the constructor call.
      errorTarget ??= _errorNode;
      if (argumentValue == null &&
          baseParameter is ParameterElementImpl &&
          baseParameter.isOptional) {
        // The parameter is an optional positional parameter for which no value
        // was provided, so use the default value.
        var evaluationResult = baseParameter.evaluationResult;
        if (evaluationResult == null) {
          // No default was provided, so the default value is null.
          argumentValue = ConstantEvaluationEngine._nullObject(_library);
        } else if (evaluationResult is DartObjectImpl) {
          argumentValue = evaluationResult;
        }
      }
      if (argumentValue != null) {
        if (!argumentValue.isInvalid &&
            !typeSystem.runtimeTypeMatch(argumentValue, parameter.type)) {
          // Mark the type mismatch error as a runtime exception if the argument
          // is statically assignable to the parameter.
          // TODO(kallentu): https://github.com/dart-lang/sdk/issues/53263
          var isEvaluationException = errorTarget is Expression &&
              _library.typeSystem.isAssignableTo(
                errorTarget.typeOrThrow,
                parameter.type,
              );
          return InvalidConstant.forEntity(errorTarget,
              CompileTimeErrorCode.CONST_CONSTRUCTOR_PARAM_TYPE_MISMATCH,
              arguments: [
                argumentValue.type.getDisplayString(),
                parameter.type.getDisplayString(),
              ],
              isRuntimeException: isEvaluationException);
        }
        if (baseParameter.isInitializingFormal) {
          var field = (parameter as FieldFormalParameterElement).field;
          if (field != null) {
            var fieldType = field.type;
            if (fieldType != parameter.type) {
              // We've already checked that the argument can be assigned to the
              // parameter; we also need to check that it can be assigned to
              // the field.
              if (!argumentValue.isInvalid &&
                  !typeSystem.runtimeTypeMatch(argumentValue, fieldType)) {
                return InvalidConstant.forEntity(errorTarget,
                    CompileTimeErrorCode.CONST_CONSTRUCTOR_PARAM_TYPE_MISMATCH,
                    arguments: [
                      argumentValue.type.getDisplayString(),
                      fieldType.getDisplayString(),
                    ]);
              }
            }
            var fieldName = field.name;
            if (_fieldMap.containsKey(fieldName)) {
              return InvalidConstant.forEntity(
                  _errorNode, CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION);
            }
            _fieldMap[fieldName] = argumentValue;
          }
        }
        _parameterMap[baseParameter.name] = argumentValue;
      }
    }
    return null;
  }

  /// Checks for errors in an explicit or implicit call to `super()`
  ///
  /// Returns an [InvalidConstant] if an error is found, or `null` otherwise.
  ///
  /// If a superinitializer was declared on the constructor declaration,
  /// [superName] and [superArguments] are the name of the super constructor
  /// referenced therein, and the arguments passed to the super constructor.
  /// Otherwise these parameters are `null`.
  InvalidConstant? _checkSuperConstructorCall({
    required String? superName,
    required List<Expression>? superArguments,
  }) {
    var superclass = definingType.superclass;
    if (superclass != null && !superclass.isDartCoreObject) {
      var superConstructor =
          superclass.lookUpConstructor(superName, _constructor.library);
      if (superConstructor == null) {
        return null;
      }

      if (superConstructor.isConst) {
        var evaluationResult = _evaluationEngine.evaluateConstructorCall(
          _library,
          _errorNode,
          superclass.typeArguments,
          superArguments ?? const [],
          superConstructor,
          _initializerVisitor,
        );
        switch (evaluationResult) {
          case DartObjectImpl():
            _fieldMap[GenericState.SUPERCLASS_FIELD] = evaluationResult;
          case InvalidConstant(isRuntimeException: false):
            // Add additional information to the error in the super constructor
            // call because the error is reported at the location of
            // [_errorNode].
            if (evaluationResult.contextMessages.isEmpty) {
              evaluationResult.contextMessages.add(DiagnosticMessageImpl(
                filePath: _constructor.source.fullName,
                length: evaluationResult.length,
                message: "The error is in the super constructor invocation "
                    "of '${_constructor.displayName}', and occurs here.",
                offset: evaluationResult.offset,
                url: null,
              ));
            } else {
              evaluationResult.contextMessages.add(
                  _stackTraceContextMessage(superConstructor, _constructor));
            }
            return InvalidConstant.copyWithEntity(evaluationResult, _errorNode);
          case InvalidConstant():
            evaluationResult.contextMessages
                .add(_stackTraceContextMessage(superConstructor, _constructor));
            return evaluationResult;
        }
      }
    }
    return null;
  }

  /// Checks that the arguments to a call to [Symbol.new] are correct.
  ///
  /// The [arguments] are the AST nodes of the arguments. The [argumentValues]
  /// are the values of the unnamed arguments. The [namedArgumentValues] are the
  /// values of the named arguments. Returns `true` if the arguments are
  /// correct, `false` otherwise.
  bool _checkSymbolArguments(List<Expression> arguments) {
    if (arguments.length != 1) {
      return false;
    }
    if (arguments[0] is NamedExpression) {
      return false;
    }
    if (firstArgument!.type != typeProvider.stringType) {
      return false;
    }
    var name = firstArgument?.toStringValue();
    if (name == null) {
      return false;
    }
    return true;
  }

  void _checkTypeParameters() {
    var typeParameters = _constructor.enclosingElement.typeParameters;
    var typeArguments = _typeArguments;
    if (typeParameters.isNotEmpty &&
        typeArguments != null &&
        typeParameters.length == typeArguments.length) {
      for (int i = 0; i < typeParameters.length; i++) {
        var typeParameter = typeParameters[i];
        var typeArgument = typeArguments[i];
        _typeParameterMap[typeParameter] = typeArgument;
      }
    }
  }

  /// Returns a context message that mimics a stack trace where [superConstructor] is
  /// called by [constructor]
  DiagnosticMessageImpl _stackTraceContextMessage(
      ConstructorElement superConstructor, ConstructorElement constructor) {
    return DiagnosticMessageImpl(
      filePath: constructor.source.fullName,
      length: constructor.nameLength,
      message: "The evaluated constructor '${superConstructor.displayName}' "
          "is called by '${constructor.displayName}' and "
          "'${constructor.displayName}' is defined here.",
      offset: constructor.nameOffset,
      url: null,
    );
  }

  /// Evaluates [node] as an instance creation expression using [constructor].
  static Constant evaluate(
    ConstantEvaluationEngine evaluationEngine,
    DeclaredVariables declaredVariables,
    LibraryElementImpl library,
    AstNode node,
    ConstructorElement constructor,
    List<DartType>? typeArguments,
    List<Expression> arguments,
    ConstantVisitor constantVisitor, {
    ConstructorInvocation? invocation,
  }) {
    if (!constructor.isConst) {
      if (node is InstanceCreationExpression) {
        var newKeyword = node.keyword;
        if (newKeyword != null) {
          return InvalidConstant.forEntity(
              newKeyword, CompileTimeErrorCode.CONST_WITH_NON_CONST);
        }
      }
      return InvalidConstant.forEntity(
          node, CompileTimeErrorCode.CONST_WITH_NON_CONST);
    }

    if (!(constructor.declaration as ConstructorElementImpl).isCycleFree) {
      // It's not safe to evaluate this constructor, so bail out.
      //
      // Instead of reporting an error at the call-sites, we will report an
      // error at each constructor in
      // [ConstantVerifier.visitConstructorDeclaration].
      return DartObjectImpl.validWithUnknownValue(
        library.typeSystem,
        constructor.returnType,
      );
    }

    var argumentValues = <DartObjectImpl>[];
    var namedNodes = <String, NamedExpression>{};
    var namedValues = <String, DartObjectImpl>{};
    for (var i = 0; i < arguments.length; i++) {
      var argument = arguments[i];

      // Use the corresponding parameter type as the default value if
      // an unresolved expression is evaluated. We do this to continue the
      // rest of the evaluation without producing unrelated errors.
      if (argument is NamedExpression) {
        var parameterType = argument.element?.type ?? InvalidTypeImpl.instance;
        var argumentConstant =
            constantVisitor._valueOf(argument.expression, parameterType);
        if (argumentConstant is! DartObjectImpl) {
          return argumentConstant;
        }

        var name = argument.name.label.name;
        namedNodes[name] = argument;
        namedValues[name] = argumentConstant;
      } else {
        var parameterType = i < constructor.parameters.length
            ? constructor.parameters[i].type
            : InvalidTypeImpl.instance;
        var argumentConstant =
            constantVisitor._valueOf(argument, parameterType);
        if (argumentConstant is! DartObjectImpl) {
          return argumentConstant;
        }

        argumentValues.add(argumentConstant);
      }
    }

    invocation ??= ConstructorInvocation(
      constructor,
      argumentValues,
      namedValues,
    );

    constructor = _followConstantRedirectionChain(constructor);
    var evaluator = _InstanceCreationEvaluator._(
      evaluationEngine,
      declaredVariables,
      library,
      evaluationEngine.configuration.errorNode(node),
      constructor,
      typeArguments,
      namedNodes: namedNodes,
      namedValues: namedValues,
      argumentValues: argumentValues,
      invocation: invocation,
    );

    if (constructor.isFactory) {
      // We couldn't find a non-factory constructor.
      // See if it's because we reached an external const factory constructor
      // that we can emulate.
      return evaluator.evaluateFactoryConstructorCall(arguments);
    } else {
      return evaluator.evaluateGenerativeConstructorCall(arguments);
    }
  }

  /// Attempt to follow the chain of factory redirections until a constructor is
  /// reached which is not a const factory constructor. Return the constant
  /// constructor which terminates the chain of factory redirections, if the
  /// chain terminates. If there is a problem (e.g. a redirection can't be
  /// found, or a cycle is encountered), the chain will be followed as far as
  /// possible and then a const factory constructor will be returned.
  static ConstructorElement _followConstantRedirectionChain(
      ConstructorElement constructor) {
    var constructorsVisited = <ConstructorElement>{};
    while (true) {
      var redirectedConstructor =
          ConstantEvaluationEngine.getConstRedirectedConstructor(constructor);
      if (redirectedConstructor == null) {
        break;
      } else {
        var constructorBase = constructor.declaration;
        constructorsVisited.add(constructorBase);
        var redirectedConstructorBase = redirectedConstructor.declaration;
        if (constructorsVisited.contains(redirectedConstructorBase)) {
          // Cycle in redirecting factory constructors--this is not allowed
          // and is checked elsewhere--see
          // [ErrorVerifier.checkForRecursiveFactoryRedirect()]).
          break;
        }
      }
      constructor = redirectedConstructor;
    }
    return constructor;
  }
}

extension on NamedType {
  bool get isTypeLiteralInConstantPattern {
    var parent = this.parent;
    return parent is TypeLiteral && parent.parent?.parent is ConstantPattern;
  }
}

extension RuntimeExtensions on TypeSystemImpl {
  /// Returns whether [obj] matches the [type] according to runtime
  /// type-checking rules.
  bool runtimeTypeMatch(
    DartObjectImpl obj,
    DartType type,
  ) {
    type = type.extensionTypeErasure;
    var objType = obj.type;
    return isSubtypeOf(objType, type);
  }
}