Enable and refactor to fix IDE0031 Use null propagation (dotnet#7902)

eng/CodeAnalysis.src.globalconfig

@@ -1524,7 +1524,7 @@ dotnet_diagnostic.IDE0029.severity = warning
 dotnet_diagnostic.IDE0030.severity = warning
 
 # IDE0031: Use null propagation
-dotnet_diagnostic.IDE0031.severity = none # TODO: warning
+dotnet_diagnostic.IDE0031.severity = warning
 
 # IDE0032: Use auto property
 dotnet_diagnostic.IDE0032.severity = silent

src/Microsoft.VisualBasic.Forms/src/Microsoft/VisualBasic/ApplicationServices/WindowsFormsApplicationBase.vb

@@ -258,9 +258,7 @@ Namespace Microsoft.VisualBasic.ApplicationServices
                     _processingUnhandledExceptionEvent = True
 
                     For Each handler As UnhandledExceptionEventHandler In _unhandledExceptionHandlers
-                        If handler IsNot Nothing Then
-                            handler.Invoke(sender, e)
-                        End If
+                        handler?.Invoke(sender, e)
                     Next
 
                     ' Now that we are out of the unhandled exception handler, treat exceptions normally again.
@@ -747,9 +745,7 @@ Namespace Microsoft.VisualBasic.ApplicationServices
                 ' Dispose on the Splash screen. (we're just swapping the order of the two If blocks.)
                 ' This is to fix the issue where the main form doesn't come to the front after the
                 ' Splash screen disappears.
-                If MainForm IsNot Nothing Then
-                    MainForm.Activate()
-                End If
+                MainForm?.Activate()
 
                 If _splashScreen IsNot Nothing AndAlso Not _splashScreen.IsDisposed Then
                     Dim disposeSplashDelegate As New DisposeDelegate(AddressOf _splashScreen.Dispose)

src/Microsoft.VisualBasic.Forms/src/Microsoft/VisualBasic/Devices/Audio.vb

@@ -118,9 +118,7 @@ Namespace Microsoft.VisualBasic
                 Debug.Assert([Enum].IsDefined(GetType(AudioPlayMode), mode), "Enum value is out of range")
 
                 ' Stopping the sound ensures it's safe to dispose it. This could happen when we change the value of m_Sound below
-                If _sound IsNot Nothing Then
-                    _sound.Stop()
-                End If
+                _sound?.Stop()
 
                 _sound = sound
 

src/Microsoft.VisualBasic.Forms/src/Microsoft/VisualBasic/Helpers/VBInputBox.vb

@@ -35,9 +35,7 @@ Namespace Microsoft.VisualBasic.CompilerServices
 
         Protected Overloads Overrides Sub Dispose(disposing As Boolean)
             If disposing Then
-                If Not (components Is Nothing) Then
-                    components.Dispose()
-                End If
+                components?.Dispose()
             End If
             MyBase.Dispose(disposing)
         End Sub

src/Microsoft.VisualBasic.Forms/src/Microsoft/VisualBasic/Logging/FileLogTraceListener.vb

@@ -584,9 +584,7 @@ Namespace Microsoft.VisualBasic.Logging
         ''' Flushes the underlying stream
         ''' </summary>
         Public Overrides Sub Flush()
-            If _stream IsNot Nothing Then
-                _stream.Flush()
-            End If
+            _stream?.Flush()
         End Sub
 
         ''' <summary>
@@ -894,9 +892,7 @@ Namespace Microsoft.VisualBasic.Logging
                         Return Reader.CurrentEncoding
                     End If
                 Finally
-                    If Reader IsNot Nothing Then
-                        Reader.Close()
-                    End If
+                    Reader?.Close()
                 End Try
             End If
 
@@ -1226,9 +1222,7 @@ Namespace Microsoft.VisualBasic.Logging
             Private Overloads Sub Dispose(disposing As Boolean)
                 If disposing Then
                     If Not _disposed Then
-                        If _stream IsNot Nothing Then
-                            _stream.Close()
-                        End If
+                        _stream?.Close()
                         _disposed = True
                     End If
                 End If

src/Microsoft.VisualBasic.Forms/src/Microsoft/VisualBasic/MyServices/Internal/ProgressDialog.vb

@@ -214,9 +214,7 @@ Namespace Microsoft.VisualBasic.MyServices.Internal
         'Form overrides dispose to clean up the component list.
         Protected Overloads Overrides Sub Dispose(disposing As Boolean)
             If disposing Then
-                If Not (_components Is Nothing) Then
-                    _components.Dispose()
-                End If
+                _components?.Dispose()
                 If _formClosableSemaphore IsNot Nothing Then
                     _formClosableSemaphore.Dispose()
                     _formClosableSemaphore = Nothing

src/Microsoft.VisualBasic/tests/UnitTests/Microsoft/VisualBasic/ApplicationServices/SingleInstanceTests.cs

@@ -349,10 +349,7 @@ public void CloseServerAfterClientConnect()
             }
             finally
             {
-                if (pipeClient != null)
-                {
-                    pipeClient.Dispose();
-                }
+                pipeClient?.Dispose();
             }
         }
 

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/CodeMarkers.cs

@@ -277,10 +277,7 @@ public static byte[] AttachCorrelationId(byte[] buffer, Guid correlationId)
             byte[] bufferWithCorrelation = new byte[s_correlationMarkBytes.Length + correlationIdBytes.Length + (buffer is not null ? buffer.Length : 0)];
             s_correlationMarkBytes.CopyTo(bufferWithCorrelation, 0);
             correlationIdBytes.CopyTo(bufferWithCorrelation, s_correlationMarkBytes.Length);
-            if (buffer is not null)
-            {
-                buffer.CopyTo(bufferWithCorrelation, s_correlationMarkBytes.Length + correlationIdBytes.Length);
-            }
+            buffer?.CopyTo(bufferWithCorrelation, s_correlationMarkBytes.Length + correlationIdBytes.Length);
 
             return bufferWithCorrelation;
         }

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/CollectionEditor.CollectionEditorCollectionForm.cs

@@ -271,10 +271,7 @@ private void CancelButton_click(object sender, EventArgs e)
                         _createdItems.Clear();
                     }
 
-                    if (_removedItems is not null)
-                    {
-                        _removedItems.Clear();
-                    }
+                    _removedItems?.Clear();
 
                     // Restore the original contents. Because objects get parented during CreateAndAddInstance, the underlying collection
                     // gets changed during add, but not other operations. Not all consumers of this dialog can roll back every single change,

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/DesignSurface.cs

@@ -382,10 +382,7 @@ protected virtual void Dispose(bool disposing)
                 {
                     try
                     {
-                        if (_host is not null)
-                        {
-                            _host.DisposeHost();
-                        }
+                        _host?.DisposeHost();
                     }
                     finally
                     {
@@ -409,10 +406,7 @@ protected virtual void Dispose(bool disposing)
         /// </summary>
         public void Flush()
         {
-            if (_host is not null)
-            {
-                _host.Flush();
-            }
+            _host?.Flush();
 
             Flushed?.Invoke(this, EventArgs.Empty);
         }

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/DesignSurfaceManager.cs

@@ -303,10 +303,7 @@ public DesignSurface CreateDesignSurface(IServiceProvider parentProvider)
             // the ones providing the event service, then whoever is providing
             // it will be responsible for updating it when new designers are created.
             DesignerEventService eventService = GetService(typeof(IDesignerEventService)) as DesignerEventService;
-            if (eventService is not null)
-            {
-                eventService.OnCreateDesigner(surface);
-            }
+            eventService?.OnCreateDesigner(surface);
 
             return surface;
         }

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/DesignerActionPanel.EditorPropertyLine.cs

@@ -792,18 +792,12 @@ protected override void OnPaint(PaintEventArgs e)
                                     }
                                     finally
                                     {
-                                        if (attrs is not null)
-                                        {
-                                            attrs.Dispose();
-                                        }
+                                        attrs?.Dispose();
                                     }
                                 }
                                 finally
                                 {
-                                    if (icon is not null)
-                                    {
-                                        icon.Dispose();
-                                    }
+                                    icon?.Dispose();
                                 }
                             }
                             catch

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/DesignerActionService.cs

@@ -259,10 +259,7 @@ private void OnVerbStatusChanged(object sender, EventArgs args)
                                 if (verb == sender)
                                 {
                                     DesignerActionUIService dapUISvc = (DesignerActionUIService)sc.GetService(typeof(DesignerActionUIService));
-                                    if (dapUISvc is not null)
-                                    {
-                                        dapUISvc.Refresh(comp); // we need to refresh, a verb on the current panel has changed its state
-                                    }
+                                    dapUISvc?.Refresh(comp); // we need to refresh, a verb on the current panel has changed its state
                                 }
                             }
                         }

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/DesignerActionUI.cs

@@ -130,10 +130,7 @@ public void Dispose()
                 if (_cmdShowDesignerActions is not null)
                 {
                     IMenuCommandService mcs = (IMenuCommandService)_serviceProvider.GetService(typeof(IMenuCommandService));
-                    if (mcs is not null)
-                    {
-                        mcs.RemoveCommand(_cmdShowDesignerActions);
-                    }
+                    mcs?.RemoveCommand(_cmdShowDesignerActions);
                 }
             }
 
@@ -568,10 +565,7 @@ private void InvalidateGlyphOnLastTransaction(object sender, DesignerTransaction
                     host.TransactionClosed -= new DesignerTransactionCloseEventHandler(InvalidateGlyphOnLastTransaction);
                 }
 
-                if (_relatedGlyphTransaction is not null)
-                {
-                    _relatedGlyphTransaction.InvalidateOwnerLocation();
-                }
+                _relatedGlyphTransaction?.InvalidateOwnerLocation();
 
                 _relatedGlyphTransaction = null;
             }

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/DesignerActionUIService.cs

@@ -34,10 +34,7 @@ public void Dispose()
             if (_serviceProvider is not null)
             {
                 IDesignerHost host = (IDesignerHost)_serviceProvider.GetService(typeof(IDesignerHost));
-                if (host is not null)
-                {
-                    host.RemoveService(typeof(DesignerActionUIService));
-                }
+                host?.RemoveService(typeof(DesignerActionUIService));
             }
         }
 

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/DesignerEventService.cs

@@ -186,10 +186,7 @@ private void OnDesignerDisposed(object sender, EventArgs e)
                 }
             }
 
-            if (_designerList is not null)
-            {
-                _designerList.Remove(host);
-            }
+            _designerList?.Remove(host);
         }
 
         /// <summary>

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/DesignerHost.cs

@@ -394,10 +394,7 @@ protected override ISite CreateSite(IComponent component, string name)
             }
             else
             {
-                if (nameCreate is not null)
-                {
-                    nameCreate.ValidateName(name);
-                }
+                nameCreate?.ValidateName(name);
             }
 
             return new Site(component, this, name, this);
@@ -472,10 +469,7 @@ internal void DisposeHost()
         /// </summary>
         internal void Flush()
         {
-            if (_loader is not null)
-            {
-                _loader.Flush();
-            }
+            _loader?.Flush();
         }
 
         /// <summary>
@@ -706,10 +700,7 @@ private void Unload()
             }
 
             ISelectionService selectionService = (ISelectionService)GetService(typeof(ISelectionService));
-            if (selectionService is not null)
-            {
-                selectionService.SetSelectedComponents(null, SelectionTypes.Replace);
-            }
+            selectionService?.SetSelectedComponents(null, SelectionTypes.Replace);
 
             // Now remove all the designers and their components.  We save the root for last.  Note that we eat any exceptions that components or their designers generate.  A bad component or designer should not prevent an unload from happening.  We do all of this in a transaction to help reduce the number of events we generate.
             _state[s_stateUnloading] = true;
@@ -1251,10 +1242,7 @@ void IDesignerLoaderHost.EndLoad(string rootClassName, bool successful, ICollect
                         errorCollection = errorList;
                         successful = false;
 
-                        if (_surface is not null)
-                        {
-                            _surface.OnLoaded(successful, errorCollection);
-                        }
+                        _surface?.OnLoaded(successful, errorCollection);
 
                         // We re-throw.  If this was a synchronous load this will error back to BeginLoad (and, as a side effect, may call us again).  For asynchronous loads we need to throw so the caller knows what happened.
                         throw;

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/ReferenceService.cs

@@ -140,10 +140,7 @@ private void OnComponentAdded(object sender, ComponentEventArgs cevent)
             if (!(compAdded.Site is INestedSite))
             {
                 _addedComponents.Add(compAdded);
-                if (_removedComponents is not null)
-                {
-                    _removedComponents.Remove(compAdded);
-                }
+                _removedComponents?.Remove(compAdded);
             }
         }
 
@@ -161,10 +158,7 @@ private void OnComponentRemoved(object sender, ComponentEventArgs cevent)
             if (!(compRemoved.Site is INestedSite))
             {
                 _removedComponents.Add(compRemoved);
-                if (_addedComponents is not null)
-                {
-                    _addedComponents.Remove(compRemoved);
-                }
+                _addedComponents?.Remove(compRemoved);
             }
         }
 

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/SelectionService.cs

@@ -176,10 +176,7 @@ internal object PrimarySelection
         /// </summary>
         internal void RemoveSelection(object sel)
         {
-            if (_selection is not null)
-            {
-                _selection.Remove(sel);
-            }
+            _selection?.Remove(sel);
         }
 
         private void ApplicationIdle(object source, EventArgs args)

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/Serialization/CodeDomComponentSerializationService.cs

@@ -793,10 +793,7 @@ private static void DeserializeDesignTimeProperties(IDesignerSerializationManage
                             foreach (DictionaryEntry de in (IDictionary)state)
                             {
                                 PropertyDescriptor prop = props[(string)de.Key];
-                                if (prop is not null)
-                                {
-                                    prop.SetValue(comp, de.Value);
-                                }
+                                prop?.SetValue(comp, de.Value);
                             }
                         }
                     }
@@ -1051,10 +1048,7 @@ private static void DeserializeEventResets(IDesignerSerializationManager manager
                                 {
                                     PropertyDescriptor prop = eventProps[eventName];
 
-                                    if (prop is not null)
-                                    {
-                                        prop.SetValue(comp, null);
-                                    }
+                                    prop?.SetValue(comp, null);
                                 }
                             }
                         }
@@ -1069,10 +1063,7 @@ private static void DeserializeModifier(IDesignerSerializationManager manager, s
                     {
                         MemberAttributes modifierValue = (MemberAttributes)state;
                         PropertyDescriptor modifierProp = TypeDescriptor.GetProperties(comp)["Modifiers"];
-                        if (modifierProp is not null)
-                        {
-                            modifierProp.SetValue(comp, modifierValue);
-                        }
+                        modifierProp?.SetValue(comp, modifierValue);
                     }
                 }
 

src/System.Windows.Forms.Design/src/System/ComponentModel/Design/Serialization/CodeDomDesignerLoader.ModifiersExtenderProvider.cs

@@ -172,10 +172,7 @@ public static void SetGenerateMember(IComponent comp, bool generate)
                 IDictionaryService dictionary = (IDictionaryService)site.GetService(typeof(IDictionaryService));
                 bool oldValue = GetGenerateMember(comp);
 
-                if (dictionary is not null)
-                {
-                    dictionary.SetValue("GenerateMember", generate);
-                }
+                dictionary?.SetValue("GenerateMember", generate);
 
                 // If the old value was true and the new value is false, we've got
                 // to remove the existing member declaration for this
@@ -219,10 +216,7 @@ public static void SetModifiers(IComponent comp, MemberAttributes modifiers)
 
                 IDictionaryService dictionary = (IDictionaryService)site.GetService(typeof(IDictionaryService));
 
-                if (dictionary is not null)
-                {
-                    dictionary.SetValue("Modifiers", modifiers);
-                }
+                dictionary?.SetValue("Modifiers", modifiers);
             }
         }
     }