change unfixed to warnings and fixed to errors, changed project settings to match

.editorconfig

@@ -152,12 +152,58 @@ dotnet_diagnostic.MEF006.severity = silent
 dotnet_diagnostic.IDE2003.severity = silent
 
 #cleared null error types
+dotnet_diagnostic.CS8597.severity = error
+dotnet_diagnostic.CS8605.severity = error
+dotnet_diagnostic.CS8606.severity = error
+dotnet_diagnostic.CS8607.severity = error
+dotnet_diagnostic.CS8608.severity = error
+dotnet_diagnostic.CS8609.severity = error
+dotnet_diagnostic.CS8610.severity = error
+dotnet_diagnostic.CS8611.severity = error
 dotnet_diagnostic.CS8612.severity = error
+dotnet_diagnostic.CS8613.severity = error
+dotnet_diagnostic.CS8614.severity = error
+dotnet_diagnostic.CS8615.severity = error
+dotnet_diagnostic.CS8621.severity = error
 dotnet_diagnostic.CS8622.severity = error
+dotnet_diagnostic.CS8624.severity = error
+dotnet_diagnostic.CS8633.severity = error
+dotnet_diagnostic.CS8634.severity = error
+dotnet_diagnostic.CS8643.severity = error
+dotnet_diagnostic.CS8644.severity = error
+dotnet_diagnostic.CS8645.severity = error
+dotnet_diagnostic.CS8655.severity = error
+dotnet_diagnostic.CS8667.severity = error
+dotnet_diagnostic.CS8670.severity = error
 dotnet_diagnostic.CS8714.severity = error
 dotnet_diagnostic.CS8762.severity = error
+dotnet_diagnostic.CS8763.severity = error
+dotnet_diagnostic.CS8764.severity = error
 dotnet_diagnostic.CS8765.severity = error
 dotnet_diagnostic.CS8766.severity = error
 dotnet_diagnostic.CS8767.severity = error
 dotnet_diagnostic.CS8768.severity = error
 dotnet_diagnostic.CS8769.severity = error
+dotnet_diagnostic.CS8770.severity = error
+dotnet_diagnostic.CS8773.severity = error
+dotnet_diagnostic.CS8774.severity = error
+dotnet_diagnostic.CS8775.severity = error
+dotnet_diagnostic.CS8776.severity = error
+dotnet_diagnostic.CS8775.severity = error
+dotnet_diagnostic.CS8777.severity = error
+
+#nullable error types still not cleaned up
+dotnet_diagnostic.CS8600.severity = warning
+dotnet_diagnostic.CS8601.severity = warning
+dotnet_diagnostic.CS8602.severity = warning
+dotnet_diagnostic.CS8603.severity = warning
+dotnet_diagnostic.CS8604.severity = warning
+dotnet_diagnostic.CS8605.severity = warning
+dotnet_diagnostic.CS8615.severity = warning
+dotnet_diagnostic.CS8617.severity = warning
+dotnet_diagnostic.CS8618.severity = warning
+dotnet_diagnostic.CS8619.severity = warning
+dotnet_diagnostic.CS8620.severity = warning
+dotnet_diagnostic.CS8625.severity = warning
+dotnet_diagnostic.CS8629.severity = warning
+dotnet_diagnostic.CS8631.severity = warning

ICSharpCode.BamlDecompiler/BamlDecompilerSettings.cs

@@ -37,9 +37,9 @@ namespace ICSharpCode.BamlDecompiler
 			}
 		}
 
-		public event PropertyChangedEventHandler PropertyChanged;
+		public event PropertyChangedEventHandler? PropertyChanged;
 
-		protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
+		protected virtual void OnPropertyChanged([CallerMemberName] string? propertyName = null)
 		{
 			if (PropertyChanged != null)
 			{

ICSharpCode.BamlDecompiler/ICSharpCode.BamlDecompiler.csproj

@@ -35,6 +35,7 @@
     <DebugSymbols>true</DebugSymbols>
     <EmbedUntrackedSources>true</EmbedUntrackedSources>
     <PublishRepositoryUrl>true</PublishRepositoryUrl>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   
   <ItemGroup>

ICSharpCode.Decompiler.PowerShell/ICSharpCode.Decompiler.PowerShell.csproj

@@ -6,6 +6,7 @@
     <CopyLocalLockFileAssemblies>true</CopyLocalLockFileAssemblies>
     <RootNamespace>ICSharpCode.Decompiler.PowerShell</RootNamespace>
     <LangVersion>8.0</LangVersion>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>

ICSharpCode.Decompiler/CSharp/ProjectDecompiler/WholeProjectDecompiler.cs

@@ -71,7 +71,7 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 
 		public AssemblyReferenceClassifier AssemblyReferenceClassifier { get; }
 
-		public IDebugInfoProvider DebugInfoProvider { get; }
+		public IDebugInfoProvider? DebugInfoProvider { get; }
 
 		/// <summary>
 		/// The MSBuild ProjectGuid to use for the new project.
@@ -106,9 +106,9 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 		public WholeProjectDecompiler(
 			DecompilerSettings settings,
 			IAssemblyResolver assemblyResolver,
-			IProjectFileWriter projectWriter,
+			IProjectFileWriter? projectWriter,
-			AssemblyReferenceClassifier assemblyReferenceClassifier,
+			AssemblyReferenceClassifier? assemblyReferenceClassifier,
-			IDebugInfoProvider debugInfoProvider)
+			IDebugInfoProvider? debugInfoProvider)
 			: this(settings, Guid.NewGuid(), assemblyResolver, projectWriter, assemblyReferenceClassifier, debugInfoProvider)
 		{
 		}
@@ -117,9 +117,9 @@ namespace ICSharpCode.Decompiler.CSharp.ProjectDecompiler
 			DecompilerSettings settings,
 			Guid projectGuid,
 			IAssemblyResolver assemblyResolver,
-			IProjectFileWriter projectWriter,
+			IProjectFileWriter? projectWriter,
-			AssemblyReferenceClassifier assemblyReferenceClassifier,
+			AssemblyReferenceClassifier? assemblyReferenceClassifier,
-			IDebugInfoProvider debugInfoProvider)
+			IDebugInfoProvider? debugInfoProvider)
 		{
 			Settings = settings ?? throw new ArgumentNullException(nameof(settings));
 			ProjectGuid = projectGuid;

ICSharpCode.Decompiler/Documentation/XmlDocLoader.cs

@@ -31,8 +31,8 @@ namespace ICSharpCode.Decompiler.Documentation
 	/// </summary>
 	public static class XmlDocLoader
 	{
-		static readonly Lazy<XmlDocumentationProvider> mscorlibDocumentation = new Lazy<XmlDocumentationProvider>(LoadMscorlibDocumentation);
+		static readonly Lazy<XmlDocumentationProvider?> mscorlibDocumentation = new Lazy<XmlDocumentationProvider?>(LoadMscorlibDocumentation);
-		static readonly ConditionalWeakTable<MetadataFile, XmlDocumentationProvider> cache = new();
+		static readonly ConditionalWeakTable<MetadataFile, XmlDocumentationProvider?> cache = new();
 
 		static XmlDocumentationProvider? LoadMscorlibDocumentation()
 		{
@@ -44,11 +44,11 @@ namespace ICSharpCode.Decompiler.Documentation
 				return null;
 		}
 
-		public static XmlDocumentationProvider MscorlibDocumentation {
+		public static XmlDocumentationProvider? MscorlibDocumentation {
 			get { return mscorlibDocumentation.Value; }
 		}
 
-		public static XmlDocumentationProvider LoadDocumentation(MetadataFile module)
+		public static XmlDocumentationProvider? LoadDocumentation(MetadataFile module)
 		{
 			if (module == null)
 				throw new ArgumentNullException(nameof(module));
@@ -56,7 +56,7 @@ namespace ICSharpCode.Decompiler.Documentation
 			{
 				if (!cache.TryGetValue(module, out XmlDocumentationProvider? xmlDoc))
 				{
-					string xmlDocFile = LookupLocalizedXmlDoc(module.FileName);
+					string? xmlDocFile = LookupLocalizedXmlDoc(module.FileName);
 					if (xmlDocFile == null)
 					{
 						xmlDocFile = FindXmlDocumentation(Path.GetFileName(module.FileName), module.GetRuntime());
@@ -79,9 +79,9 @@ namespace ICSharpCode.Decompiler.Documentation
 		static readonly string referenceAssembliesPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ProgramFilesX86), @"Reference Assemblies\Microsoft\\Framework");
 		static readonly string frameworkPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Windows), @"Microsoft.NET\Framework");
 
-		static string FindXmlDocumentation(string assemblyFileName, TargetRuntime runtime)
+		static string? FindXmlDocumentation(string assemblyFileName, TargetRuntime runtime)
 		{
-			string fileName;
+			string? fileName;
 			switch (runtime)
 			{
 				case TargetRuntime.Net_1_0:

ICSharpCode.Decompiler/ICSharpCode.Decompiler.csproj

@@ -32,7 +32,6 @@
     <SignAssembly>True</SignAssembly>
     <AssemblyOriginatorKeyFile>ICSharpCode.Decompiler.snk</AssemblyOriginatorKeyFile>
     <NoWarn>1701;1702;1591;1573</NoWarn>
-    <WarningsAsErrors>nullable</WarningsAsErrors>
 
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
     <DebugType>embedded</DebugType>

ICSharpCode.Decompiler/IL/Transforms/TransformExpressionTrees.cs

@@ -447,7 +447,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			return delegateType;
 		}
 
-		(Func<ILInstruction>?, IType) ConvertArrayIndex(CallInstruction invocation)
+		(Func<ILInstruction?>?, IType) ConvertArrayIndex(CallInstruction invocation)
 		{
 			if (invocation.Arguments.Count != 2)
 				return (null, SpecialType.UnknownType);

ICSharpCode.Decompiler/Semantics/OperatorResolveResult.cs

@@ -30,7 +30,7 @@ namespace ICSharpCode.Decompiler.Semantics
 	public class OperatorResolveResult : ResolveResult
 	{
 		readonly ExpressionType operatorType;
-		readonly IMethod userDefinedOperatorMethod;
+		readonly IMethod? userDefinedOperatorMethod;
 		readonly IList<ResolveResult> operands;
 		readonly bool isLiftedOperator;
 
@@ -43,7 +43,7 @@ namespace ICSharpCode.Decompiler.Semantics
 			this.operands = operands;
 		}
 
-		public OperatorResolveResult(IType resultType, ExpressionType operatorType, IMethod userDefinedOperatorMethod, bool isLiftedOperator, IList<ResolveResult> operands)
+		public OperatorResolveResult(IType resultType, ExpressionType operatorType, IMethod? userDefinedOperatorMethod, bool isLiftedOperator, IList<ResolveResult> operands)
 			: base(resultType)
 		{
 			if (operands == null)

ICSharpCode.ILSpyCmd/ICSharpCode.ILSpyCmd.csproj

@@ -8,7 +8,7 @@
     <IsPackable>true</IsPackable>
     <PackAsTool>true</PackAsTool>
     <InvariantGlobalization>true</InvariantGlobalization>
-
+    <Nullable>enable</Nullable>
     <NeutralLanguage>en-US</NeutralLanguage>
     <GenerateAssemblyVersionAttribute>False</GenerateAssemblyVersionAttribute>
     <GenerateAssemblyFileVersionAttribute>False</GenerateAssemblyFileVersionAttribute>

ICSharpCode.ILSpyCmd/ValidationAttributes.cs

@@ -14,7 +14,7 @@ namespace ICSharpCode.ILSpyCmd
 		{
 		}
 
-		protected override ValidationResult IsValid(object value, ValidationContext context)
+		protected override ValidationResult? IsValid(object? value, ValidationContext context)
 		{
 			if (value is ILSpyCmdProgram obj)
 			{
@@ -30,7 +30,7 @@ namespace ICSharpCode.ILSpyCmd
 	[AttributeUsage(AttributeTargets.Property)]
 	public sealed class FileExistsOrNullAttribute : ValidationAttribute
 	{
-		protected override ValidationResult IsValid(object value, ValidationContext validationContext)
+		protected override ValidationResult? IsValid(object? value, ValidationContext validationContext)
 		{
 			var path = value as string;
 			if (string.IsNullOrEmpty(path))
@@ -55,7 +55,7 @@ namespace ICSharpCode.ILSpyCmd
 	[AttributeUsage(AttributeTargets.Property)]
 	public sealed class FilesExistAttribute : ValidationAttribute
 	{
-		protected override ValidationResult IsValid(object value, ValidationContext validationContext)
+		protected override ValidationResult? IsValid(object? value, ValidationContext validationContext)
 		{
 			switch (value)
 			{
@@ -65,7 +65,7 @@ namespace ICSharpCode.ILSpyCmd
 				{
 					foreach (string path in paths)
 					{
-						ValidationResult result = ValidatePath(path);
+						ValidationResult? result = ValidatePath(path);
 						if (result != ValidationResult.Success)
 							return result;
 					}
@@ -75,7 +75,7 @@ namespace ICSharpCode.ILSpyCmd
 					return new ValidationResult($"File '{value}' does not exist!");
 			}
 
-			ValidationResult ValidatePath(string path)
+			ValidationResult? ValidatePath(string path)
 			{
 				if (!string.IsNullOrWhiteSpace(path))
 				{

ICSharpCode.ILSpyX/Analyzers/AnalyzerHelpers.cs

@@ -54,7 +54,7 @@ namespace ICSharpCode.ILSpyX.Analyzers
 			switch (customAttribute.Parent.Kind)
 			{
 				case HandleKind.MethodDefinition:
-					IMethod parent = (IMethod)ts.MainModule.ResolveEntity(customAttribute.Parent);
+					IMethod? parent = (IMethod?)ts.MainModule.ResolveEntity(customAttribute.Parent);
 					return parent?.AccessorOwner ?? parent;
 				case HandleKind.FieldDefinition:
 				case HandleKind.PropertyDefinition:

ICSharpCode.ILSpyX/ICSharpCode.ILSpyX.csproj

@@ -4,8 +4,7 @@
     <TargetFramework>net8.0</TargetFramework>
     <Nullable>enable</Nullable>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-    <WarningsAsErrors>nullable</WarningsAsErrors>
+    <Nullable>enable</Nullable>
-
     <SignAssembly>True</SignAssembly>
     <AssemblyOriginatorKeyFile>..\ICSharpCode.Decompiler\ICSharpCode.Decompiler.snk</AssemblyOriginatorKeyFile>
 

ICSharpCode.ILSpyX/TreeView/TreeTraversal.cs

@@ -43,7 +43,7 @@ namespace ICSharpCode.ILSpyX.TreeView
 		/// <param name="input">The root elements of the forest.</param>
 		/// <param name="recursion">The function that gets the children of an element.</param>
 		/// <returns>Iterator that enumerates the tree structure in pre-order.</returns>
-		public static IEnumerable<T> PreOrder<T>(IEnumerable<T> input, Func<T, IEnumerable<T>> recursion)
+		public static IEnumerable<T> PreOrder<T>(IEnumerable<T> input, Func<T, IEnumerable<T>?> recursion)
 		{
 			Stack<IEnumerator<T>> stack = new Stack<IEnumerator<T>>();
 			try
@@ -55,7 +55,7 @@ namespace ICSharpCode.ILSpyX.TreeView
 					{
 						T element = stack.Peek().Current;
 						yield return element;
-						IEnumerable<T> children = recursion(element);
+						IEnumerable<T>? children = recursion(element);
 						if (children != null)
 						{
 							stack.Push(children.GetEnumerator());

ILSpy.BamlDecompiler.Tests/ILSpy.BamlDecompiler.Tests.csproj

@@ -4,6 +4,7 @@
   <PropertyGroup>
     <IsWindowsX64 Condition="$([MSBuild]::IsOsPlatform('Windows')) And $([System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture) == X64">true</IsWindowsX64>
     <IsWindowsARM64 Condition="$([MSBuild]::IsOsPlatform('Windows')) And $([System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture) == ARM64">true</IsWindowsARM64>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <PropertyGroup>

ILSpy.BamlDecompiler/BamlResourceEntryNode.cs

@@ -33,13 +33,13 @@ namespace ILSpy.BamlDecompiler
 {
 	public sealed class BamlResourceEntryNode : ResourceEntryNode
 	{
-		public BamlResourceEntryNode(string key, Func<Stream> data) : base(key, data)
+		public BamlResourceEntryNode(string key, Func<Stream?> data) : base(key, data)
 		{
 		}
 
 		public override bool View(TabPageModel tabPage)
 		{
-			IHighlightingDefinition highlighting = null;
+			IHighlightingDefinition? highlighting = null;
 
 			tabPage.SupportsLanguageSwitching = false;
 			tabPage.ShowTextView(textView => textView.RunWithCancellation(

ILSpy.BamlDecompiler/ILSpy.BamlDecompiler.csproj

@@ -9,6 +9,7 @@
     <BaseAddress>6488064</BaseAddress>
     <UseWpf>true</UseWpf>
     <EnableWindowsTargeting>true</EnableWindowsTargeting>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)' == 'Debug'">

ILSpy.ReadyToRun/ILSpy.ReadyToRun.csproj

@@ -11,6 +11,7 @@
     <UseWpf>true</UseWpf>
     <IsPackable>false</IsPackable>
     <EnableWindowsTargeting>true</EnableWindowsTargeting>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)' == 'Debug'">

ILSpy.ReadyToRun/ReadyToRunOptionPage.xaml.cs

@@ -114,9 +114,9 @@ namespace ICSharpCode.ILSpy.ReadyToRun
 			}
 		}
 
-		public event PropertyChangedEventHandler PropertyChanged;
+		public event PropertyChangedEventHandler? PropertyChanged;
 
-		protected virtual void OnPropertyChanged(string propertyName)
+		protected virtual void OnPropertyChanged(string? propertyName)
 		{
 			if (PropertyChanged != null)
 			{

ILSpy.Tests/ILSpy.Tests.csproj

@@ -17,6 +17,7 @@
 
     <SignAssembly>True</SignAssembly>
     <AssemblyOriginatorKeyFile>..\ICSharpCode.Decompiler\ICSharpCode.Decompiler.snk</AssemblyOriginatorKeyFile>
+
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)' == 'Debug'">

ILSpy/Controls/CustomDialog.cs

@@ -113,9 +113,9 @@ namespace ICSharpCode.ILSpy.Controls
 			}
 		}
 
-		void ButtonClick(object sender, EventArgs e)
+		void ButtonClick(object? sender, EventArgs e)
 		{
-			result = (int)((Control)sender).Tag;
+			result = ((int?)(sender as Control)?.Tag) ?? -1;
 			this.Close();
 		}
 

ILSpy/Docking/DockWorkspace.cs

@@ -82,7 +82,7 @@ namespace ICSharpCode.ILSpy.Docking
 			}
 		}
 
-		private void Documents_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
+		private void Documents_CollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
 		{
 			var collection = (PaneCollection<TabPageModel>)sender;
 			if (e.Action == NotifyCollectionChangedAction.Add)

ILSpy/TreeNodes/AssemblyListTreeNode.cs

@@ -203,7 +203,9 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			}
 			return null;
 
-			static SharpTreeNodeCollection? ExpandAndGetChildren(SharpTreeNode node)
+
+
+			static SharpTreeNodeCollection ExpandAndGetChildren(SharpTreeNode node)
 			{
 				if (node is not PackageFolderTreeNode)
 					return null;

ILSpy/TreeNodes/ResourceNodes/CursorResourceEntryNode.cs

@@ -50,7 +50,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 
 	sealed class CursorResourceEntryNode : ResourceEntryNode
 	{
-		public CursorResourceEntryNode(string key, Func<Stream> openStream)
+		public CursorResourceEntryNode(string key, Func<Stream?> openStream)
 			: base(key, openStream)
 		{
 		}

TestPlugin/CustomOptionPage.xaml.cs

@@ -86,7 +86,7 @@ namespace TestPlugin
 			}
 		}
 
-		public event PropertyChangedEventHandler PropertyChanged;
+		public event PropertyChangedEventHandler? PropertyChanged;
 
 		protected virtual void OnPropertyChanged(string propertyName)
 		{

TestPlugin/MainMenuCommand.cs

@@ -21,7 +21,7 @@ namespace TestPlugin
 	[PartCreationPolicy(CreationPolicy.Shared)]
 	public class UnloadAllAssembliesCommand : SimpleCommand
 	{
-		public override void Execute(object parameter)
+		public override void Execute(object? parameter)
 		{
 			foreach (var loadedAssembly in MainWindow.Instance.CurrentAssemblyList.GetAssemblies())
 			{

TestPlugin/TestPlugin.csproj

@@ -5,6 +5,7 @@
     <AssemblyName>Test.Plugin</AssemblyName>
     <UseWpf>true</UseWpf>
     <EnableWindowsTargeting>true</EnableWindowsTargeting>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)' == 'Debug'">