private void AnalyzeClassDeclaration()

in src/Microsoft.VisualStudio.SDK.Analyzers/VSSDK002PackageRegistrationMatchesBaseTypeAnalyzer.cs [74:115]
37 lines of code
8 McCabe index (conditional complexity)

        private void AnalyzeClassDeclaration(SyntaxNodeAnalysisContext context, INamedTypeSymbol packageType, INamedTypeSymbol asyncPackageType)
        {
            var declaration = (ClassDeclarationSyntax)context.Node;
            BaseTypeSyntax? baseType = declaration.BaseList?.Types.FirstOrDefault();
            if (baseType == null)
            {
                return;
            }

            var baseTypeSymbol = context.SemanticModel.GetSymbolInfo(baseType.Type, context.CancellationToken).Symbol?.OriginalDefinition as ITypeSymbol;

            if (Utils.IsEqualToOrDerivedFrom(baseTypeSymbol, packageType))
            {
                INamedTypeSymbol packageRegistrationType = context.Compilation.GetTypeByMetadataName(Types.PackageRegistrationAttribute.FullName);
                INamedTypeSymbol userClassSymbol = context.SemanticModel.GetDeclaredSymbol(declaration, context.CancellationToken);
                AttributeData? packageRegistrationInstance = userClassSymbol?.GetAttributes().FirstOrDefault(a => SymbolEqualityComparer.Default.Equals(a.AttributeClass, packageRegistrationType));
                if (packageRegistrationInstance == null)
                {
                    return;
                }

                if (!(packageRegistrationInstance.NamedArguments.FirstOrDefault(kv => kv.Key == Types.PackageRegistrationAttribute.AllowsBackgroundLoading).Value.Value is bool allowsBackgroundLoading))
                {
                    allowsBackgroundLoading = false;
                }

                bool isAsyncPackageBaseType = Utils.IsEqualToOrDerivedFrom(baseTypeSymbol, asyncPackageType);

                if (isAsyncPackageBaseType != allowsBackgroundLoading)
                {
                    var attributeSyntax = packageRegistrationInstance.ApplicationSyntaxReference.GetSyntax(context.CancellationToken) as AttributeSyntax;
                    if (attributeSyntax is object)
                    {
                        AttributeArgumentSyntax? allowBackgroundLoadingSyntax = attributeSyntax.ArgumentList.Arguments.FirstOrDefault(a => a.NameEquals?.Name?.Identifier.Text == Types.PackageRegistrationAttribute.AllowsBackgroundLoading);
                        Location location = allowBackgroundLoadingSyntax?.GetLocation() ?? attributeSyntax.GetLocation();
                        ImmutableDictionary<string, string> properties = ImmutableDictionary.Create<string, string>()
                            .Add(BaseTypeDiagnosticPropertyName, isAsyncPackageBaseType ? Types.AsyncPackage.TypeName : Types.Package.TypeName);
                        context.ReportDiagnostic(Diagnostic.Create(Descriptor, location, properties));
                    }
                }
            }
        }