pkg/analyzer/lib/src/lint/linter.dart

// Copyright (c) 2015, 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:io';

import 'package:analyzer/dart/analysis/declared_variables.dart';
import 'package:analyzer/dart/analysis/features.dart';
import 'package:analyzer/dart/ast/ast.dart';
import 'package:analyzer/dart/ast/token.dart';
import 'package:analyzer/dart/constant/value.dart';
import 'package:analyzer/dart/element/element.dart';
import 'package:analyzer/dart/element/scope.dart';
import 'package:analyzer/dart/element/type_provider.dart';
import 'package:analyzer/dart/element/type_system.dart';
import 'package:analyzer/error/error.dart';
import 'package:analyzer/error/listener.dart';
import 'package:analyzer/file_system/file_system.dart' as file_system;
import 'package:analyzer/src/dart/ast/ast.dart';
import 'package:analyzer/src/dart/ast/token.dart';
import 'package:analyzer/src/dart/constant/compute.dart';
import 'package:analyzer/src/dart/constant/constant_verifier.dart';
import 'package:analyzer/src/dart/constant/evaluation.dart';
import 'package:analyzer/src/dart/constant/potentially_constant.dart';
import 'package:analyzer/src/dart/constant/utilities.dart';
import 'package:analyzer/src/dart/element/element.dart';
import 'package:analyzer/src/dart/element/inheritance_manager3.dart';
import 'package:analyzer/src/dart/element/type_system.dart';
import 'package:analyzer/src/error/codes.dart';
import 'package:analyzer/src/generated/engine.dart'
    show AnalysisErrorInfo, AnalysisErrorInfoImpl, AnalysisOptions;
import 'package:analyzer/src/generated/resolver.dart' show ScopeResolverVisitor;
import 'package:analyzer/src/generated/source.dart' show LineInfo;
import 'package:analyzer/src/lint/analysis.dart';
import 'package:analyzer/src/lint/config.dart';
import 'package:analyzer/src/lint/io.dart';
import 'package:analyzer/src/lint/linter_visitor.dart' show NodeLintRegistry;
import 'package:analyzer/src/lint/project.dart';
import 'package:analyzer/src/lint/pub.dart';
import 'package:analyzer/src/lint/registry.dart';
import 'package:analyzer/src/services/lint.dart' show Linter;
import 'package:analyzer/src/workspace/workspace.dart';
import 'package:glob/glob.dart';
import 'package:path/path.dart' as p;

export 'package:analyzer/src/lint/linter_visitor.dart' show NodeLintRegistry;

typedef Printer = void Function(String msg);

/// Describes a String in valid camel case format.
@deprecated // Never intended for public use.
class CamelCaseString {
  static final _camelCaseMatcher = RegExp(r'[A-Z][a-z]*');
  static final _camelCaseTester = RegExp(r'^([_$]*)([A-Z?$]+[a-z0-9]*)+$');

  final String value;

  CamelCaseString(this.value) {
    if (!isCamelCase(value)) {
      throw ArgumentError('$value is not CamelCase');
    }
  }

  String get humanized => _humanize(value);

  @override
  String toString() => value;

  static bool isCamelCase(String name) => _camelCaseTester.hasMatch(name);

  static String _humanize(String camelCase) =>
      _camelCaseMatcher.allMatches(camelCase).map((m) => m.group(0)).join(' ');
}

/// Dart source linter.
class DartLinter implements AnalysisErrorListener {
  final errors = <AnalysisError>[];

  final LinterOptions options;
  final Reporter reporter;

  /// The total number of sources that were analyzed.  Only valid after
  /// [lintFiles] has been called.
  late int numSourcesAnalyzed;

  /// Creates a new linter.
  DartLinter(this.options, {this.reporter = const PrintingReporter()});

  Future<Iterable<AnalysisErrorInfo>> lintFiles(List<File> files) async {
    List<AnalysisErrorInfo> errors = [];
    final lintDriver = LintDriver(options);
    errors.addAll(await lintDriver.analyze(files.where((f) => isDartFile(f))));
    numSourcesAnalyzed = lintDriver.numSourcesAnalyzed;
    files.where((f) => isPubspecFile(f)).forEach((p) {
      numSourcesAnalyzed++;
      return errors.addAll(_lintPubspecFile(p));
    });
    return errors;
  }

  Iterable<AnalysisErrorInfo> lintPubspecSource(
      {required String contents, String? sourcePath}) {
    var results = <AnalysisErrorInfo>[];

    var sourceUrl = sourcePath == null ? null : p.toUri(sourcePath);

    var spec = Pubspec.parse(contents, sourceUrl: sourceUrl);

    for (Linter lint in options.enabledLints) {
      if (lint is LintRule) {
        LintRule rule = lint;
        var visitor = rule.getPubspecVisitor();
        if (visitor != null) {
          // Analyzer sets reporters; if this file is not being analyzed,
          // we need to set one ourselves.  (Needless to say, when pubspec
          // processing gets pushed down, this hack can go away.)
          if (sourceUrl != null) {
            var source = createSource(sourceUrl);
            rule.reporter = ErrorReporter(
              this,
              source,
              isNonNullableByDefault: false,
            );
          }
          try {
            spec.accept(visitor);
          } on Exception catch (e) {
            reporter.exception(LinterException(e.toString()));
          }
          if (rule._locationInfo.isNotEmpty) {
            results.addAll(rule._locationInfo);
            rule._locationInfo.clear();
          }
        }
      }
    }

    return results;
  }

  @override
  void onError(AnalysisError error) => errors.add(error);

  Iterable<AnalysisErrorInfo> _lintPubspecFile(File sourceFile) =>
      lintPubspecSource(
          contents: sourceFile.readAsStringSync(),
          sourcePath: options.resourceProvider.pathContext
              .normalize(sourceFile.absolute.path));
}

class FileGlobFilter extends LintFilter {
  List<Glob> includes;
  List<Glob> excludes;

  FileGlobFilter(Iterable<String> includeGlobs, Iterable<String> excludeGlobs)
      : includes = includeGlobs.map((glob) => Glob(glob)).toList(),
        excludes = excludeGlobs.map((glob) => Glob(glob)).toList();

  @override
  bool filter(AnalysisError lint) {
    // TODO specify order
    return excludes.any((glob) => glob.matches(lint.source.fullName)) &&
        !includes.any((glob) => glob.matches(lint.source.fullName));
  }
}

class Group implements Comparable<Group> {
  /// Defined rule groups.
  static const Group errors =
      Group._('errors', description: 'Possible coding errors.');
  static const Group pub = Group._('pub',
      description: 'Pub-related rules.',
      link: Hyperlink('See the <strong>Pubspec Format</strong>',
          'https://dart.dev/tools/pub/pubspec'));
  static const Group style = Group._('style',
      description:
          'Matters of style, largely derived from the official Dart Style Guide.',
      link: Hyperlink('See the <strong>Style Guide</strong>',
          'https://dart.dev/guides/language/effective-dart/style'));

  /// List of builtin groups in presentation order.
  static const Iterable<Group> builtin = [errors, style, pub];

  final String name;
  final bool custom;
  final String description;
  final Hyperlink? link;

  factory Group(String name, {String description = '', Hyperlink? link}) {
    var n = name.toLowerCase();
    return builtin.firstWhere((g) => g.name == n,
        orElse: () =>
            Group._(name, custom: true, description: description, link: link));
  }

  const Group._(this.name,
      {this.custom = false, required this.description, this.link});

  @override
  int compareTo(Group other) => name.compareTo(other.name);
}

class Hyperlink {
  final String label;
  final String href;
  final bool bold;

  const Hyperlink(this.label, this.href, {this.bold = false});

  String get html => '<a href="$href">${_emph(label)}</a>';

  String _emph(String msg) => bold ? '<strong>$msg</strong>' : msg;
}

/// The result of attempting to evaluate an expression.
class LinterConstantEvaluationResult {
  /// The value of the expression, or `null` if has [errors].
  final DartObject? value;

  /// The errors reported during the evaluation.
  final List<AnalysisError> errors;

  LinterConstantEvaluationResult(this.value, this.errors);
}

/// Provides access to information needed by lint rules that is not available
/// from AST nodes or the element model.
abstract class LinterContext {
  List<LinterContextUnit> get allUnits;

  AnalysisOptions get analysisOptions;

  LinterContextUnit get currentUnit;

  DeclaredVariables get declaredVariables;

  InheritanceManager3 get inheritanceManager;

  WorkspacePackage? get package;

  TypeProvider get typeProvider;

  TypeSystem get typeSystem;

  /// Return `true` if it would be valid for the given [expression] to have
  /// a keyword of `const`.
  ///
  /// The [expression] is expected to be a node within one of the compilation
  /// units in [allUnits].
  ///
  /// Note that this method can cause constant evaluation to occur, which can be
  /// computationally expensive.
  bool canBeConst(Expression expression);

  /// Return `true` if it would be valid for the given constructor declaration
  /// [node] to have a keyword of `const`.
  ///
  /// The [node] is expected to be a node within one of the compilation
  /// units in [allUnits].
  ///
  /// Note that this method can cause constant evaluation to occur, which can be
  /// computationally expensive.
  bool canBeConstConstructor(ConstructorDeclaration node);

  /// Return the result of evaluating the given expression.
  LinterConstantEvaluationResult evaluateConstant(Expression node);

  /// Return `true` if the given [unit] is in a test directory.
  bool inTestDir(CompilationUnit unit);

  /// Return `true` if the [feature] is enabled in the library being linted.
  bool isEnabled(Feature feature);

  /// Resolve the name `id` or `id=` (if [setter] is `true`) an the location
  /// of the [node], according to the "16.35 Lexical Lookup" of the language
  /// specification.
  LinterNameInScopeResolutionResult resolveNameInScope(
      String id, bool setter, AstNode node);
}

/// Implementation of [LinterContext]
class LinterContextImpl implements LinterContext {
  static final testDirectories = [
    '${p.separator}test${p.separator}',
    '${p.separator}integration_test${p.separator}',
    '${p.separator}test_driver${p.separator}',
    '${p.separator}testing${p.separator}',
  ];

  @override
  final List<LinterContextUnit> allUnits;

  @override
  final AnalysisOptions analysisOptions;

  @override
  final LinterContextUnit currentUnit;

  @override
  final DeclaredVariables declaredVariables;

  @override
  final WorkspacePackage? package;

  @override
  final TypeProvider typeProvider;

  @override
  final TypeSystemImpl typeSystem;

  @override
  final InheritanceManager3 inheritanceManager;

  LinterContextImpl(
    this.allUnits,
    this.currentUnit,
    this.declaredVariables,
    this.typeProvider,
    this.typeSystem,
    this.inheritanceManager,
    this.analysisOptions,
    this.package,
  );

  @override
  bool canBeConst(Expression expression) {
    if (expression is InstanceCreationExpressionImpl) {
      return _canBeConstInstanceCreation(expression);
    } else if (expression is TypedLiteralImpl) {
      return _canBeConstTypedLiteral(expression);
    } else {
      return false;
    }
  }

  @override
  bool canBeConstConstructor(covariant ConstructorDeclarationImpl node) {
    var element = node.declaredElement!;

    ClassElement classElement = element.enclosingElement;
    if (classElement.hasNonFinalField) return false;

    var oldKeyword = node.constKeyword;
    try {
      temporaryConstConstructorElements[element] = true;
      node.constKeyword = KeywordToken(Keyword.CONST, node.offset);
      return !_hasConstantVerifierError(node);
    } finally {
      temporaryConstConstructorElements[element] = null;
      node.constKeyword = oldKeyword;
    }
  }

  @override
  LinterConstantEvaluationResult evaluateConstant(Expression node) {
    var unitElement = currentUnit.unit.declaredElement!;
    var source = unitElement.source;
    var libraryElement = unitElement.library as LibraryElementImpl;

    var errorListener = RecordingErrorListener();
    var errorReporter = ErrorReporter(
      errorListener,
      source,
      isNonNullableByDefault: libraryElement.isNonNullableByDefault,
    );

    var evaluationEngine = ConstantEvaluationEngine(
      declaredVariables: declaredVariables,
      isNonNullableByDefault: isEnabled(Feature.non_nullable),
    );

    var dependencies = <ConstantEvaluationTarget>[];
    node.accept(
      ReferenceFinder(dependencies.add),
    );

    computeConstants(
      declaredVariables,
      dependencies,
      libraryElement.featureSet,
    );

    var visitor = ConstantVisitor(
      evaluationEngine,
      libraryElement,
      errorReporter,
    );

    var value = node.accept(visitor);
    return LinterConstantEvaluationResult(value, errorListener.errors);
  }

  @override
  bool inTestDir(CompilationUnit unit) {
    var path = unit.declaredElement?.source.fullName;
    return path != null && testDirectories.any(path.contains);
  }

  @override
  bool isEnabled(Feature feature) {
    var unitElement = currentUnit.unit.declaredElement!;
    return unitElement.library.featureSet.isEnabled(feature);
  }

  @override
  LinterNameInScopeResolutionResult resolveNameInScope(
      String id, bool setter, AstNode node) {
    Scope? scope;
    for (AstNode? context = node; context != null; context = context.parent) {
      scope = ScopeResolverVisitor.getNodeNameScope(context);
      if (scope != null) {
        break;
      }
    }

    if (scope != null) {
      var lookupResult = scope.lookup(id);
      var idElement = lookupResult.getter;
      var idEqElement = lookupResult.setter;

      var requestedElement = setter ? idEqElement : idElement;
      var differentElement = setter ? idElement : idEqElement;

      if (requestedElement != null) {
        return LinterNameInScopeResolutionResult._requestedName(
          requestedElement,
        );
      }

      if (differentElement != null) {
        return LinterNameInScopeResolutionResult._differentName(
          differentElement,
        );
      }
    }

    return const LinterNameInScopeResolutionResult._none();
  }

  bool _canBeConstInstanceCreation(InstanceCreationExpressionImpl node) {
    //
    // Verify that the invoked constructor is a const constructor.
    //
    var element = node.constructorName.staticElement;
    if (element == null || !element.isConst) {
      return false;
    }

    // Ensure that dependencies (e.g. default parameter values) are computed.
    var implElement = element.declaration as ConstructorElementImpl;
    implElement.computeConstantDependencies();

    //
    // Verify that the evaluation of the constructor would not produce an
    // exception.
    //
    var oldKeyword = node.keyword;
    try {
      node.keyword = KeywordToken(Keyword.CONST, node.offset);
      return !_hasConstantVerifierError(node);
    } finally {
      node.keyword = oldKeyword;
    }
  }

  bool _canBeConstTypedLiteral(TypedLiteralImpl node) {
    var oldKeyword = node.constKeyword;
    try {
      node.constKeyword = KeywordToken(Keyword.CONST, node.offset);
      return !_hasConstantVerifierError(node);
    } finally {
      node.constKeyword = oldKeyword;
    }
  }

  /// Return `true` if [ConstantVerifier] reports an error for the [node].
  bool _hasConstantVerifierError(AstNode node) {
    var unitElement = currentUnit.unit.declaredElement!;
    var libraryElement = unitElement.library as LibraryElementImpl;

    var dependenciesFinder = ConstantExpressionsDependenciesFinder();
    node.accept(dependenciesFinder);
    computeConstants(
      declaredVariables,
      dependenciesFinder.dependencies.toList(),
      libraryElement.featureSet,
    );

    var listener = _ConstantAnalysisErrorListener();
    var errorReporter = ErrorReporter(
      listener,
      unitElement.source,
      isNonNullableByDefault: libraryElement.isNonNullableByDefault,
    );

    node.accept(
      ConstantVerifier(
        errorReporter,
        libraryElement,
        declaredVariables,
      ),
    );
    return listener.hasConstError;
  }
}

class LinterContextUnit {
  final String content;

  final CompilationUnit unit;

  LinterContextUnit(this.content, this.unit);
}

/// Thrown when an error occurs in linting.
class LinterException implements Exception {
  /// A message describing the error.
  final String? message;

  /// Creates a new LinterException with an optional error [message].
  const LinterException([this.message]);

  @override
  String toString() =>
      message == null ? "LinterException" : "LinterException: $message";
}

/// The result of resolving of a basename `id` in a scope.
class LinterNameInScopeResolutionResult {
  /// The element with the requested basename, `null` is [isNone].
  final Element? element;

  /// The state of the result.
  final _LinterNameInScopeResolutionResultState _state;

  const LinterNameInScopeResolutionResult._differentName(this.element)
      : _state = _LinterNameInScopeResolutionResultState.differentName;

  const LinterNameInScopeResolutionResult._none()
      : element = null,
        _state = _LinterNameInScopeResolutionResultState.none;

  const LinterNameInScopeResolutionResult._requestedName(this.element)
      : _state = _LinterNameInScopeResolutionResultState.requestedName;

  bool get isDifferentName =>
      _state == _LinterNameInScopeResolutionResultState.differentName;

  bool get isNone => _state == _LinterNameInScopeResolutionResultState.none;

  bool get isRequestedName =>
      _state == _LinterNameInScopeResolutionResultState.requestedName;

  @override
  String toString() {
    return '(state: $_state, element: $element)';
  }
}

/// Linter options.
class LinterOptions extends DriverOptions {
  Iterable<LintRule> enabledLints;
  String? analysisOptions;
  LintFilter? filter;
  late file_system.ResourceProvider resourceProvider;

  // todo (pq): consider migrating to named params (but note Linter dep).
  LinterOptions([Iterable<LintRule>? enabledLints, this.analysisOptions])
      : enabledLints = enabledLints ?? Registry.ruleRegistry;

  void configure(LintConfig config) {
    enabledLints = Registry.ruleRegistry.where((LintRule rule) =>
        !config.ruleConfigs.any((rc) => rc.disables(rule.name)));
    filter = FileGlobFilter(config.fileIncludes, config.fileExcludes);
  }
}

/// Filtered lints are omitted from linter output.
abstract class LintFilter {
  bool filter(AnalysisError lint);
}

/// Describes a lint rule.
abstract class LintRule extends Linter implements Comparable<LintRule> {
  /// Description (in markdown format) suitable for display in a detailed lint
  /// description.
  final String details;

  /// Short description suitable for display in console output.
  final String description;

  /// Lint group (for example, 'style').
  final Group group;

  /// Lint maturity (stable|experimental).
  final Maturity maturity;

  /// Lint name.
  @override
  final String name;

  /// Until pubspec analysis is pushed into the analyzer proper, we need to
  /// do some extra book-keeping to keep track of details that will help us
  /// constitute AnalysisErrorInfos.
  final List<AnalysisErrorInfo> _locationInfo = <AnalysisErrorInfo>[];

  LintRule({
    required this.name,
    required this.group,
    required this.description,
    required this.details,
    this.maturity = Maturity.stable,
  });

  /// A list of incompatible rule ids.
  List<String> get incompatibleRules => const [];

  @override
  LintCode get lintCode => _LintCode(name, description);

  @override
  int compareTo(LintRule other) {
    var g = group.compareTo(other.group);
    if (g != 0) {
      return g;
    }
    return name.compareTo(other.name);
  }

  /// Return a visitor to be passed to provide access to Dart project context
  /// and to perform project-level analyses.
  @Deprecated('Use LinterContext instead')
  ProjectVisitor? getProjectVisitor() => null;

  /// Return a visitor to be passed to pubspecs to perform lint
  /// analysis.
  /// Lint errors are reported via this [Linter]'s error [reporter].
  PubspecVisitor? getPubspecVisitor() => null;

  @override
  AstVisitor? getVisitor() => null;

  void reportLint(AstNode? node,
      {List<Object> arguments = const [],
      ErrorCode? errorCode,
      bool ignoreSyntheticNodes = true}) {
    if (node != null && (!node.isSynthetic || !ignoreSyntheticNodes)) {
      reporter.reportErrorForNode(errorCode ?? lintCode, node, arguments);
    }
  }

  void reportLintForOffset(int offset, int length,
      {List<Object> arguments = const [], ErrorCode? errorCode}) {
    reporter.reportErrorForOffset(
        errorCode ?? lintCode, offset, length, arguments);
  }

  void reportLintForToken(Token? token,
      {List<Object> arguments = const [],
      ErrorCode? errorCode,
      bool ignoreSyntheticTokens = true}) {
    if (token != null && (!token.isSynthetic || !ignoreSyntheticTokens)) {
      reporter.reportErrorForToken(errorCode ?? lintCode, token, arguments);
    }
  }

  void reportPubLint(PSNode node) {
    var source = node.source;
    // Cache error and location info for creating AnalysisErrorInfos
    AnalysisError error = AnalysisError(
        source, node.span.start.offset, node.span.length, lintCode);
    LineInfo lineInfo = LineInfo.fromContent(source.contents.data);

    _locationInfo.add(AnalysisErrorInfoImpl([error], lineInfo));

    // Then do the reporting
    reporter.reportError(error);
  }
}

class Maturity implements Comparable<Maturity> {
  static const Maturity stable = Maturity._('stable', ordinal: 0);
  static const Maturity experimental = Maturity._('experimental', ordinal: 1);
  static const Maturity deprecated = Maturity._('deprecated', ordinal: 2);

  final String name;
  final int ordinal;

  factory Maturity(String name, {required int ordinal}) {
    switch (name.toLowerCase()) {
      case 'stable':
        return stable;
      case 'experimental':
        return experimental;
      case 'deprecated':
        return deprecated;
      default:
        return Maturity._(name, ordinal: ordinal);
    }
  }

  const Maturity._(this.name, {required this.ordinal});

  @override
  int compareTo(Maturity other) => ordinal - other.ordinal;
}

/// [LintRule]s that implement this interface want to process only some types
/// of AST nodes, and will register their processors in the registry.
abstract class NodeLintRule {
  /// This method is invoked to let the [LintRule] register node processors
  /// in the given [registry].
  ///
  /// The node processors may use the provided [context] to access information
  /// that is not available from the AST nodes or their associated elements.
  void registerNodeProcessors(NodeLintRegistry registry, LinterContext context);
}

/// [LintRule]s that implement this interface want to process only some types
/// of AST nodes, and will register their processors in the registry.
///
/// This class exists solely to allow a smoother transition from analyzer
/// version 0.33.*.  It will be removed in a future analyzer release, so please
/// use [NodeLintRule] instead.
@deprecated
abstract class NodeLintRuleWithContext extends NodeLintRule {}

class PrintingReporter implements Reporter {
  final Printer _print;

  const PrintingReporter([this._print = print]);

  @override
  void exception(LinterException exception) {
    _print('EXCEPTION: $exception');
  }

  @override
  void warn(String message) {
    _print('WARN: $message');
  }
}

abstract class Reporter {
  void exception(LinterException exception);

  void warn(String message);
}

/// Linter implementation.
class SourceLinter implements DartLinter, AnalysisErrorListener {
  @override
  final errors = <AnalysisError>[];
  @override
  final LinterOptions options;
  @override
  final Reporter reporter;

  @override
  late int numSourcesAnalyzed;

  SourceLinter(this.options, {this.reporter = const PrintingReporter()});

  @override
  Future<Iterable<AnalysisErrorInfo>> lintFiles(List<File> files) async {
    List<AnalysisErrorInfo> errors = [];
    final lintDriver = LintDriver(options);
    errors.addAll(await lintDriver.analyze(files.where((f) => isDartFile(f))));
    numSourcesAnalyzed = lintDriver.numSourcesAnalyzed;
    files.where((f) => isPubspecFile(f)).forEach((p) {
      numSourcesAnalyzed++;
      return errors.addAll(_lintPubspecFile(p));
    });
    return errors;
  }

  @override
  Iterable<AnalysisErrorInfo> lintPubspecSource(
      {required String contents, String? sourcePath}) {
    var results = <AnalysisErrorInfo>[];

    var sourceUrl = sourcePath == null ? null : p.toUri(sourcePath);

    var spec = Pubspec.parse(contents, sourceUrl: sourceUrl);

    for (Linter lint in options.enabledLints) {
      if (lint is LintRule) {
        LintRule rule = lint;
        var visitor = rule.getPubspecVisitor();
        if (visitor != null) {
          // Analyzer sets reporters; if this file is not being analyzed,
          // we need to set one ourselves.  (Needless to say, when pubspec
          // processing gets pushed down, this hack can go away.)
          if (sourceUrl != null) {
            var source = createSource(sourceUrl);
            rule.reporter = ErrorReporter(
              this,
              source,
              isNonNullableByDefault: false,
            );
          }
          try {
            spec.accept(visitor);
          } on Exception catch (e) {
            reporter.exception(LinterException(e.toString()));
          }

          var locationInfo = rule._locationInfo;
          if (!identical(null, locationInfo) && locationInfo.isNotEmpty) {
            results.addAll(rule._locationInfo);
            rule._locationInfo.clear();
          }
        }
      }
    }

    return results;
  }

  @override
  void onError(AnalysisError error) => errors.add(error);

  @override
  Iterable<AnalysisErrorInfo> _lintPubspecFile(File sourceFile) =>
      lintPubspecSource(
          contents: sourceFile.readAsStringSync(), sourcePath: sourceFile.path);
}

/// An error listener that only records whether any constant related errors have
/// been reported.
class _ConstantAnalysisErrorListener extends AnalysisErrorListener {
  /// A flag indicating whether any constant related errors have been reported
  /// to this listener.
  bool hasConstError = false;

  @override
  void onError(AnalysisError error) {
    ErrorCode errorCode = error.errorCode;
    if (errorCode is CompileTimeErrorCode) {
      switch (errorCode) {
        case CompileTimeErrorCode
            .CONST_CONSTRUCTOR_WITH_FIELD_INITIALIZED_BY_NON_CONST:
        case CompileTimeErrorCode.CONST_EVAL_TYPE_BOOL:
        case CompileTimeErrorCode.CONST_EVAL_TYPE_BOOL_INT:
        case CompileTimeErrorCode.CONST_EVAL_TYPE_BOOL_NUM_STRING:
        case CompileTimeErrorCode.CONST_EVAL_TYPE_INT:
        case CompileTimeErrorCode.CONST_EVAL_TYPE_NUM:
        case CompileTimeErrorCode.CONST_EVAL_THROWS_EXCEPTION:
        case CompileTimeErrorCode.CONST_EVAL_THROWS_IDBZE:
        case CompileTimeErrorCode
            .CONST_MAP_KEY_EXPRESSION_TYPE_IMPLEMENTS_EQUALS:
        case CompileTimeErrorCode.CONST_SET_ELEMENT_TYPE_IMPLEMENTS_EQUALS:
        case CompileTimeErrorCode.CONST_WITH_NON_CONST:
        case CompileTimeErrorCode.CONST_WITH_NON_CONSTANT_ARGUMENT:
        case CompileTimeErrorCode.CONST_WITH_TYPE_PARAMETERS:
        case CompileTimeErrorCode.INVALID_CONSTANT:
        case CompileTimeErrorCode.MISSING_CONST_IN_LIST_LITERAL:
        case CompileTimeErrorCode.MISSING_CONST_IN_MAP_LITERAL:
        case CompileTimeErrorCode.MISSING_CONST_IN_SET_LITERAL:
        case CompileTimeErrorCode.NON_CONSTANT_LIST_ELEMENT:
        case CompileTimeErrorCode.NON_CONSTANT_MAP_ELEMENT:
        case CompileTimeErrorCode.NON_CONSTANT_MAP_KEY:
        case CompileTimeErrorCode.NON_CONSTANT_MAP_VALUE:
        case CompileTimeErrorCode.NON_CONSTANT_SET_ELEMENT:
          hasConstError = true;
      }
    }
  }
}

class _LintCode extends LintCode {
  static final registry = <String, _LintCode>{};

  factory _LintCode(String name, String message) {
    return registry[name + message] ??= _LintCode._(name, message);
  }

  _LintCode._(String name, String message) : super(name, message);
}

/// The state of a [LinterNameInScopeResolutionResult].
enum _LinterNameInScopeResolutionResultState {
  /// Indicates that no element was found.
  none,

  /// Indicates that an element with the requested name was found.
  requestedName,

  /// Indicates that an element with the same basename, but different name
  /// was found.
  differentName
}