Add nullability annotations to some tree nodes.

ICSharpCode.ILSpyX/TreeView/SharpTreeNode.cs

@@ -21,21 +21,21 @@ using System.Collections.Generic;
 using System.Collections.Specialized;
 using System.ComponentModel;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 
-#nullable disable
-
 using ICSharpCode.ILSpyX.TreeView.PlatformAbstractions;
 
 namespace ICSharpCode.ILSpyX.TreeView
 {
 	public partial class SharpTreeNode : INotifyPropertyChanged
 	{
+		[AllowNull]
 		protected static ITreeNodeImagesProvider ImagesProvider { get; private set; }
 		public static void SetImagesProvider(ITreeNodeImagesProvider provider) => ImagesProvider = provider;
 
-		SharpTreeNodeCollection modelChildren;
-		internal SharpTreeNode modelParent;
+		SharpTreeNodeCollection? modelChildren;
+		internal SharpTreeNode? modelParent;
 		bool isVisible = true;
 
 		void UpdateIsVisible(bool parentIsVisible, bool updateFlattener)
@@ -53,7 +53,7 @@ namespace ICSharpCode.ILSpyX.TreeView
 					node = node.listParent;
 				}
 				// Remember the removed nodes:
-				List<SharpTreeNode> removedNodes = null;
+				List<SharpTreeNode>? removedNodes = null;
 				if (updateFlattener && !newIsVisible)
 				{
 					removedNodes = VisibleDescendantsAndSelf().ToList();
@@ -118,19 +118,19 @@ namespace ICSharpCode.ILSpyX.TreeView
 			}
 		}
 
-		public SharpTreeNode Parent {
+		public SharpTreeNode? Parent {
 			get { return modelParent; }
 		}
 
-		public virtual object Text {
+		public virtual object? Text {
 			get { return null; }
 		}
 
-		public virtual object Icon {
+		public virtual object? Icon {
 			get { return null; }
 		}
 
-		public virtual object ToolTip {
+		public virtual object? ToolTip {
 			get { return null; }
 		}
 
@@ -199,7 +199,7 @@ namespace ICSharpCode.ILSpyX.TreeView
 					while (removeEnd.modelChildren != null && removeEnd.modelChildren.Count > 0)
 						removeEnd = removeEnd.modelChildren.Last();
 
-					List<SharpTreeNode> removedNodes = null;
+					List<SharpTreeNode>? removedNodes = null;
 					int visibleIndexOfRemoval = 0;
 					if (node.isVisible)
 					{
@@ -221,11 +221,11 @@ namespace ICSharpCode.ILSpyX.TreeView
 			}
 			if (e.NewItems != null)
 			{
-				SharpTreeNode insertionPos;
+				SharpTreeNode? insertionPos;
 				if (e.NewStartingIndex == 0)
 					insertionPos = null;
 				else
-					insertionPos = modelChildren[e.NewStartingIndex - 1];
+					insertionPos = modelChildren?[e.NewStartingIndex - 1];
 
 				foreach (SharpTreeNode node in e.NewItems)
 				{
@@ -260,7 +260,7 @@ namespace ICSharpCode.ILSpyX.TreeView
 
 		#region Expanding / LazyLoading
 
-		public virtual object ExpandedIcon {
+		public virtual object? ExpandedIcon {
 			get { return Icon; }
 		}
 
@@ -371,13 +371,13 @@ namespace ICSharpCode.ILSpyX.TreeView
 
 		public IEnumerable<SharpTreeNode> Ancestors()
 		{
-			for (SharpTreeNode n = this.Parent; n != null; n = n.Parent)
+			for (SharpTreeNode? n = this.Parent; n != null; n = n.Parent)
 				yield return n;
 		}
 
 		public IEnumerable<SharpTreeNode> AncestorsAndSelf()
 		{
-			for (SharpTreeNode n = this; n != null; n = n.Parent)
+			for (SharpTreeNode? n = this; n != null; n = n.Parent)
 				yield return n;
 		}
 
@@ -402,7 +402,7 @@ namespace ICSharpCode.ILSpyX.TreeView
 			}
 		}
 
-		public virtual string LoadEditText()
+		public virtual string? LoadEditText()
 		{
 			return null;
 		}
@@ -699,7 +699,7 @@ namespace ICSharpCode.ILSpyX.TreeView
 
 		#region INotifyPropertyChanged Members
 
-		public event PropertyChangedEventHandler PropertyChanged;
+		public event PropertyChangedEventHandler? PropertyChanged;
 
 		public void RaisePropertyChanged(string name)
 		{
@@ -725,10 +725,10 @@ namespace ICSharpCode.ILSpyX.TreeView
 		{
 		}
 
-		public override string ToString()
+		public override string? ToString()
 		{
 			// used for keyboard navigation
-			object text = this.Text;
+			object? text = this.Text;
 			return text != null ? text.ToString() : string.Empty;
 		}
 	}

ILSpy/Analyzers/AnalyzerEntityTreeNode.cs

@@ -35,7 +35,7 @@ namespace ICSharpCode.ILSpy.Analyzers
 	/// </summary>
 	public abstract class AnalyzerEntityTreeNode : AnalyzerTreeNode, IMemberTreeNode
 	{
-		public abstract IEntity Member { get; }
+		public abstract IEntity? Member { get; }
 
 		public IEntity? SourceMember { get; protected set; }
 
@@ -65,13 +65,12 @@ namespace ICSharpCode.ILSpy.Analyzers
 			}
 			foreach (LoadedAssembly asm in removedAssemblies)
 			{
-				if (this.Member.ParentModule.MetadataFile == asm.GetMetadataFileOrNull())
+				if (this.Member.ParentModule!.MetadataFile == asm.GetMetadataFileOrNull())
 					return false; // remove this node
 			}
 			this.Children.RemoveAll(
 				delegate (SharpTreeNode n) {
-					AnalyzerTreeNode an = n as AnalyzerTreeNode;
-					return an == null || !an.HandleAssemblyListChanged(removedAssemblies, addedAssemblies);
+					return n is not AnalyzerTreeNode an || !an.HandleAssemblyListChanged(removedAssemblies, addedAssemblies);
 				});
 			return true;
 		}

ILSpy/Analyzers/TreeNodes/AnalyzedEventTreeNode.cs

@@ -17,6 +17,8 @@
 // DEALINGS IN THE SOFTWARE.
 
 using System;
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.ILSpy.TreeNodes;
@@ -57,6 +59,7 @@ namespace ICSharpCode.ILSpy.Analyzers.TreeNodes
 			foreach (var lazy in Analyzers)
 			{
 				var analyzer = lazy.Value;
+				Debug.Assert(analyzer != null);
 				if (analyzer.Show(analyzedEvent))
 				{
 					this.Children.Add(new AnalyzerSearchTreeNode(analyzedEvent, analyzer, lazy.Metadata?.Header));
@@ -64,10 +67,10 @@ namespace ICSharpCode.ILSpy.Analyzers.TreeNodes
 			}
 		}
 
-		bool TryFindBackingField(IEvent analyzedEvent, out IField backingField)
+		bool TryFindBackingField(IEvent analyzedEvent, [NotNullWhen(true)] out IField? backingField)
 		{
 			backingField = null;
-			foreach (var field in analyzedEvent.DeclaringTypeDefinition.GetFields(options: GetMemberOptions.IgnoreInheritedMembers))
+			foreach (var field in analyzedEvent.DeclaringTypeDefinition?.GetFields(options: GetMemberOptions.IgnoreInheritedMembers) ?? [])
 			{
 				if (field.Name == analyzedEvent.Name && field.Accessibility == Decompiler.TypeSystem.Accessibility.Private)
 				{

ILSpy/Analyzers/TreeNodes/AnalyzedFieldTreeNode.cs

@@ -17,6 +17,7 @@
 // DEALINGS IN THE SOFTWARE.
 
 using System;
+using System.Diagnostics;
 
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.ILSpy.TreeNodes;
@@ -45,6 +46,7 @@ namespace ICSharpCode.ILSpy.Analyzers.TreeNodes
 			foreach (var lazy in Analyzers)
 			{
 				var analyzer = lazy.Value;
+				Debug.Assert(analyzer != null);
 				if (analyzer.Show(analyzedField))
 				{
 					this.Children.Add(new AnalyzerSearchTreeNode(analyzedField, analyzer, lazy.Metadata?.Header));

ILSpy/Analyzers/TreeNodes/AnalyzedMethodTreeNode.cs

@@ -17,6 +17,7 @@
 // DEALINGS IN THE SOFTWARE.
 
 using System;
+using System.Diagnostics;
 
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.ILSpy.TreeNodes;
@@ -47,9 +48,10 @@ namespace ICSharpCode.ILSpy.Analyzers.TreeNodes
 			foreach (var lazy in Analyzers)
 			{
 				var analyzer = lazy.Value;
+				Debug.Assert(analyzer != null);
 				if (analyzer.Show(analyzedMethod))
 				{
-					this.Children.Add(new AnalyzerSearchTreeNode(analyzedMethod, analyzer, lazy.Metadata.Header));
+					this.Children.Add(new AnalyzerSearchTreeNode(analyzedMethod, analyzer, lazy.Metadata!.Header));
 				}
 			}
 		}

ILSpy/Analyzers/TreeNodes/AnalyzedModuleTreeNode.cs

@@ -18,6 +18,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Windows;
 
 using ICSharpCode.Decompiler.TypeSystem;
@@ -44,16 +45,17 @@ namespace ICSharpCode.ILSpy.Analyzers.TreeNodes
 
 		public override object Text => analyzedModule.AssemblyName;
 
-		public override object ToolTip => analyzedModule.MetadataFile?.FileName;
+		public override object? ToolTip => analyzedModule.MetadataFile?.FileName;
 
 		protected override void LoadChildren()
 		{
 			foreach (var lazy in Analyzers)
 			{
 				var analyzer = lazy.Value;
+				Debug.Assert(analyzer != null);
 				if (analyzer.Show(analyzedModule))
 				{
-					this.Children.Add(new AnalyzerSearchTreeNode(analyzedModule, analyzer, lazy.Metadata.Header));
+					this.Children.Add(new AnalyzerSearchTreeNode(analyzedModule, analyzer, lazy.Metadata!.Header));
 				}
 			}
 		}
@@ -69,7 +71,7 @@ namespace ICSharpCode.ILSpy.Analyzers.TreeNodes
 			MessageBus.Send(this, new NavigateToReferenceEventArgs(analyzedModule.MetadataFile));
 		}
 
-		public override IEntity Member => null;
+		public override IEntity? Member => null;
 
 		public override bool HandleAssemblyListChanged(ICollection<LoadedAssembly> removedAssemblies, ICollection<LoadedAssembly> addedAssemblies)
 		{
@@ -84,8 +86,7 @@ namespace ICSharpCode.ILSpy.Analyzers.TreeNodes
 			}
 			this.Children.RemoveAll(
 				delegate (SharpTreeNode n) {
-					AnalyzerTreeNode an = n as AnalyzerTreeNode;
-					return an == null || !an.HandleAssemblyListChanged(removedAssemblies, addedAssemblies);
+					return n is not AnalyzerTreeNode an || !an.HandleAssemblyListChanged(removedAssemblies, addedAssemblies);
 				});
 			return true;
 		}

ILSpy/Analyzers/TreeNodes/AnalyzedPropertyTreeNode.cs

@@ -17,6 +17,7 @@
 // DEALINGS IN THE SOFTWARE.
 
 using System;
+using System.Diagnostics;
 
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.ILSpy.TreeNodes;
@@ -53,9 +54,10 @@ namespace ICSharpCode.ILSpy.Analyzers.TreeNodes
 			foreach (var lazy in Analyzers)
 			{
 				var analyzer = lazy.Value;
+				Debug.Assert(analyzer != null);
 				if (analyzer.Show(analyzedProperty))
 				{
-					this.Children.Add(new AnalyzerSearchTreeNode(analyzedProperty, analyzer, lazy.Metadata.Header));
+					this.Children.Add(new AnalyzerSearchTreeNode(analyzedProperty, analyzer, lazy.Metadata!.Header));
 				}
 			}
 		}

ILSpy/Analyzers/TreeNodes/AnalyzedTypeTreeNode.cs

@@ -17,6 +17,7 @@
 // DEALINGS IN THE SOFTWARE.
 
 using System;
+using System.Diagnostics;
 
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.ILSpy.TreeNodes;
@@ -45,9 +46,10 @@ namespace ICSharpCode.ILSpy.Analyzers.TreeNodes
 			foreach (var lazy in Analyzers)
 			{
 				var analyzer = lazy.Value;
+				Debug.Assert(analyzer != null);
 				if (analyzer.Show(analyzedType))
 				{
-					this.Children.Add(new AnalyzerSearchTreeNode(analyzedType, analyzer, lazy.Metadata.Header));
+					this.Children.Add(new AnalyzerSearchTreeNode(analyzedType, analyzer, lazy.Metadata!.Header));
 				}
 			}
 		}

ILSpy/AssemblyTree/AssemblyTreeModel.cs

@@ -602,7 +602,7 @@ namespace ICSharpCode.ILSpy.AssemblyTree
 			List<string> path = new List<string>();
 			while (node.Parent != null)
 			{
-				path.Add(node.ToString());
+				path.Add(node.ToString()!);
 				node = node.Parent;
 			}
 			path.Reverse();

ILSpy/TextView/DecompilerTextView.cs

@@ -1100,7 +1100,11 @@ namespace ICSharpCode.ILSpy.TextView
 			SaveFileDialog dlg = new SaveFileDialog();
 			dlg.DefaultExt = language.FileExtension;
 			dlg.Filter = language.Name + "|*" + language.FileExtension + Properties.Resources.AllFiles;
-			dlg.FileName = WholeProjectDecompiler.CleanUpFileName(treeNodes.First().Text.ToString(), language.FileExtension);
+			string? nodeText = treeNodes.First().Text?.ToString();
+			if (!string.IsNullOrWhiteSpace(nodeText))
+			{
+				dlg.FileName = WholeProjectDecompiler.CleanUpFileName(nodeText, language.FileExtension);
+			}
 			if (dlg.ShowDialog() == true)
 			{
 				SaveToDisk(new DecompilationContext(language, treeNodes.ToArray(), options), dlg.FileName);