Examples of errors detected by the V3042 diagnostic

V3042. Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the same object.

Xamarin.Forms

V3042 Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the Element object Xamarin.Forms.Platform.WinRT MasterDetailPageRenderer.cs 288

void UpdateTitle()
{
  if (Element?.Detail == null)
    return;

   ((ITitleProvider)this).Title =
     (Element.Detail as NavigationPage)
       ?.CurrentPage?.Title ?? Element.Title
                            ?? Element?.Title;
}

.NET Core Libraries (CoreFX)

V3042 Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the 'sym' object SymbolStore.cs 56

private static void InsertChildNoGrow(Symbol child)
{
  ....
  while (sym?.nextSameName != null)
  {
    sym = sym.nextSameName;
  }

  Debug.Assert(sym != null && sym.nextSameName == null);
  sym.nextSameName = child; // <=
  ....
}

.NET Core Libraries (CoreFX)

V3042 Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the 'property' object JsonClassInfo.AddProperty.cs 179

internal JsonPropertyInfo CreatePolymorphicProperty(....)
{
  JsonPropertyInfo runtimeProperty
    = CreateProperty(property.DeclaredPropertyType,    // <=
                     runtimePropertyType,
                     property.ImplementedPropertyType, // <=
                     property?.PropertyInfo,           // <=
                     Type,
                     options);
  ....
}

Azure PowerShell

V3042 Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the 'imageAndOsType' object VirtualMachineScaleSetStrategy.cs 81

internal static ResourceConfig<VirtualMachineScaleSet>
CreateVirtualMachineScaleSetConfig(...., ImageAndOsType imageAndOsType, ....)
{
  ....
  VirtualMachineProfile = new VirtualMachineScaleSetVMProfile
  {
    OsProfile = new VirtualMachineScaleSetOSProfile
    {
        ....,
        WindowsConfiguration =
          imageAndOsType.CreateWindowsConfiguration(),  // <=
        ....,
    },
    StorageProfile = new VirtualMachineScaleSetStorageProfile
    {
        ImageReference = imageAndOsType?.Image,  // <=
        DataDisks = DataDiskStrategy.CreateVmssDataDisks(
          imageAndOsType?.DataDiskLuns, dataDisks)  // <=
    },
  },
  ....
}

Azure PowerShell

V3042 Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the 'existingContacts' object RemoveAzureKeyVaultCertificateContact.cs 123

public override void ExecuteCmdlet()
{
  ....
  List<PSKeyVaultCertificateContact> existingContacts;

  try
  {
    existingContacts = this.DataServiceClient.
                       GetCertificateContacts(VaultName)?.ToList();
  }
  catch (KeyVaultErrorException exception)
  {
    ....
    existingContacts = null;
  }

  foreach (var email in EmailAddress)
  {
    existingContacts.RemoveAll(....);  // <=
  }
  ....
}

osu!

V3042 [CWE-476] Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the 'val.NewValue' object TournamentTeam.cs 41

public TournamentTeam()
{
  Acronym.ValueChanged += val =>
  {
    if (....)
      FlagName.Value = val.NewValue.Length >= 2     // <=
        ? val.NewValue?.Substring(0, 2).ToUpper()
        : string.Empty;
  };
  ....
}

Similar errors can be found in some other places:

• V3042 [CWE-476] Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the 'val.NewValue' object TournamentTeam.cs 48

osu!

V3042 [CWE-476] Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the 'api' object SetupScreen.cs 77

private void reload()
{
  ....
  new ActionableInfo
  {
    Label = "Current User",
    ButtonText = "Change Login",
    Action = () =>
    {
      api.Logout();     // <=
      ....
    },
    Value = api?.LocalUser.Value.Username,
    ....
  },
  ....
}

Ryujinx

V3042 Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the 'data' object Client.cs 254

public void ReceiveLoop(int clientId)
{
    ....
    byte[] data = Receive(clientId);

    if (data.Length == 0)
    {
        continue;
    }
    ....
}

private byte[] Receive(int clientId, int timeout = 0)
{
    ....
    var result = _client?.Receive(ref endPoint);

    if (result.Length > 0)
    {
        ....
    }

    return result;
    ....
}

LINQ to DB

V3042 Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the '_update' object SqlUpdateStatement.cs 60

public override ISqlTableSource? GetTableSource(ISqlTableSource table)
{
  ....
  if (table == _update?.Table)
    return _update.Table;
  ....
}

DotNetNuke

V3042 Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the 'module.DesktopModule' object Converters.cs 67

public static ModuleItem ConvertToModuleItem(ModuleInfo module)
  => new ModuleItem
{
  Id = module.ModuleID,
  Title = module.ModuleTitle,
  FriendlyName = module.DesktopModule.FriendlyName, // <=
  EditContentUrl = GetModuleEditContentUrl(module),
  EditSettingUrl = GetModuleEditSettingUrl(module),
  IsPortable = module.DesktopModule?.IsPortable,    // <=
  AllTabs = module.AllTabs,
};

DotNetNuke

V3042 Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the 'PortalSettings.Current' object PagesMenuController.cs 47

public IDictionary<string, object> GetSettings(MenuItem menuItem)
{
  var settings = new Dictionary<string, object>
  {
    { "canSeePagesList",
      this.securityService.CanViewPageList(menuItem.MenuId) },

    { "portalName",
      PortalSettings.Current.PortalName },              // <=

    { "currentPagePermissions",
      this.securityService.GetCurrentPagePermissions() },

    { "currentPageName",
      PortalSettings.Current?.ActiveTab?.TabName },     // <=

    { "productSKU",
      DotNetNukeContext.Current.Application.SKU },

    { "isAdmin",
      this.securityService.IsPageAdminUser() },

    { "currentParentHasChildren",
      PortalSettings.Current?.ActiveTab?.HasChildren },  // <=

    { "isAdminHostSystemPage",
      this.securityService.IsAdminHostSystemPage() },
  };

  return settings;
}

Unity C# reference source code

V3042 Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the 'version' object UpmPackageDocs.cs 38

public static string FetchBuiltinDescription(....)
{
  return string.IsNullOrEmpty(version?.packageInfo?.description) ?
    string.Format(L10n.Tr(....), version.displayName) :
    version.packageInfo.description.Split(....)[0];
}

Power-Fx

V3042 [CWE-476] Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the 'mergeExpandValue' object TabularDataQueryOptions.cs 282

internal bool AppendExpandQueryOptions(ExpandQueryOptions mergeExpandValue)
{
  ....
  ExpandQueryOptions[mergeExpandValue.ExpandInfo.ExpandPath] =
    mergeExpandValue?.Clone();
  return true;
}

Power-Fx

V3042 [CWE-476] Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the 'node' object ResolvedObjectHelpers.cs 45

public static FormulaValue ResolvedObjectError(ResolvedObjectNode node)
{
    return new ErrorValue(node.IRContext, new ExpressionError()
    {
        Message = $"Unrecognized symbol {node?.Value?.GetType()?.Name}".Trim(),
        Span = node.IRContext.SourceContext,
        Kind = ErrorKind.Validation
    });
}

Similar errors can be found in some other places:

• V3042 [CWE-476] Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the 'node' object ResolvedObjectHelpers.cs 48

Power-Fx

V3042 [CWE-476] Possible NullReferenceException. The '?.' and '.' operators are used for accessing members of the 'other.Fields' object FormulaTypeSchema.cs 118

public override bool Equals(object o)
{
  return o is FormulaTypeSchema other &&
    Type.Equals(other.Type) &&
    Description == other.Description &&
    Help == other.Help &&
    Fields?.Count() == other.Fields?.Count() &&
    (Fields?.All(
      (thisKvp) => other.Fields.TryGetValue(thisKvp.Key, out var otherValue) &&
      (thisKvp.Value?.Equals(otherValue) ?? otherValue == null)) ?? true);
}