Fix NRT warnings in ILSpyX

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

@@ -5,6 +5,7 @@
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <CopyLocalLockFileAssemblies>true</CopyLocalLockFileAssemblies>
     <RootNamespace>ICSharpCode.Decompiler.PowerShell</RootNamespace>
+    <LangVersion>8.0</LangVersion>
   </PropertyGroup>
 
   <Import Project="..\packages.props" />

ICSharpCode.Decompiler.PowerShell/NullAttributes.cs

@@ -0,0 +1,37 @@
+#if !NETCORE
+
+#nullable enable
+
+namespace System.Diagnostics.CodeAnalysis
+{
+	[AttributeUsage(AttributeTargets.Property | AttributeTargets.Parameter | AttributeTargets.ReturnValue, AllowMultiple = true)]
+	internal sealed class NotNullIfNotNullAttribute : Attribute
+	{
+		public string ParameterName { get; }
+
+		public NotNullIfNotNullAttribute(string parameterName)
+		{
+			ParameterName = parameterName;
+		}
+	}
+
+	[AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
+	internal sealed class NotNullWhenAttribute : Attribute
+	{
+		public NotNullWhenAttribute(bool returnValue)
+		{
+			ReturnValue = returnValue;
+		}
+
+		public bool ReturnValue { get; }
+	}
+
+	[AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
+	internal sealed class DoesNotReturnIfAttribute : Attribute
+	{
+		public DoesNotReturnIfAttribute(bool parameterValue) => ParameterValue = parameterValue;
+
+		public bool ParameterValue { get; }
+	}
+}
+#endif

ICSharpCode.ILSpyX/AssemblyList.cs

@@ -23,6 +23,7 @@ using System.Collections.Immutable;
 using System.Collections.ObjectModel;
 using System.Collections.Specialized;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Linq;
 using System.Threading;
@@ -70,6 +71,9 @@ namespace ICSharpCode.ILSpyX
 		/// </summary>
 		internal AssemblyList()
 		{
+			ownerThread = Thread.CurrentThread;
+			manager = null!;
+			listName = "Testing Only";
 		}
 
 		internal AssemblyList(AssemblyListManager manager, string listName)

ICSharpCode.ILSpyX/AssemblyListManager.cs

@@ -53,7 +53,11 @@ namespace ICSharpCode.ILSpyX
 			XElement doc = this.settingsProvider["AssemblyLists"];
 			foreach (var list in doc.Elements("List"))
 			{
-				AssemblyLists.Add((string)list.Attribute("name"));
+				var name = (string?)list.Attribute("name");
+				if (name != null)
+				{
+					AssemblyLists.Add(name);
+				}
 			}
 		}
 
@@ -82,7 +86,7 @@ namespace ICSharpCode.ILSpyX
 			{
 				foreach (var list in doc.Elements("List"))
 				{
-					if ((string)list.Attribute("name") == listName)
+					if ((string?)list.Attribute("name") == listName)
 					{
 						return new AssemblyList(this, list);
 					}
@@ -114,13 +118,13 @@ namespace ICSharpCode.ILSpyX
 		{
 			this.settingsProvider.Update(
 				delegate (XElement root) {
-					XElement doc = root.Element("AssemblyLists");
+					XElement? doc = root.Element("AssemblyLists");
 					if (doc == null)
 					{
 						doc = new XElement("AssemblyLists");
 						root.Add(doc);
 					}
-					XElement listElement = doc.Elements("List").FirstOrDefault(e => (string)e.Attribute("name") == list.ListName);
+					XElement? listElement = doc.Elements("List").FirstOrDefault(e => (string?)e.Attribute("name") == list.ListName);
 					if (listElement != null)
 						listElement.ReplaceWith(list.SaveAsXml());
 					else
@@ -145,12 +149,12 @@ namespace ICSharpCode.ILSpyX
 			{
 				this.settingsProvider.Update(
 					delegate (XElement root) {
-						XElement doc = root.Element("AssemblyLists");
+						XElement? doc = root.Element("AssemblyLists");
 						if (doc == null)
 						{
 							return;
 						}
-						XElement listElement = doc.Elements("List").FirstOrDefault(e => (string)e.Attribute("name") == Name);
+						XElement? listElement = doc.Elements("List").FirstOrDefault(e => (string?)e.Attribute("name") == Name);
 						if (listElement != null)
 							listElement.Remove();
 					});
@@ -164,7 +168,7 @@ namespace ICSharpCode.ILSpyX
 			AssemblyLists.Clear();
 			this.settingsProvider.Update(
 				delegate (XElement root) {
-					XElement doc = root.Element("AssemblyLists");
+					XElement? doc = root.Element("AssemblyLists");
 					if (doc == null)
 					{
 						return;

ICSharpCode.ILSpyX/LoadedAssemblyExtensions.cs

@@ -50,7 +50,7 @@ namespace ICSharpCode.ILSpyX
 		{
 			if (file == null)
 				throw new ArgumentNullException(nameof(file));
-			LoadedAssembly loadedAssembly;
+			LoadedAssembly? loadedAssembly;
 			lock (LoadedAssembly.loadedAssemblies)
 			{
 				if (!LoadedAssembly.loadedAssemblies.TryGetValue(file, out loadedAssembly))

ICSharpCode.ILSpyX/PdbProvider/DebugInfoUtils.cs

@@ -17,8 +17,8 @@
 // DEALINGS IN THE SOFTWARE.
 
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
-using System.Linq;
 using System.Reflection.Metadata;
 using System.Reflection.PortableExecutable;
 using System.Runtime.InteropServices;
@@ -26,24 +26,26 @@ using System.Runtime.InteropServices;
 using ICSharpCode.Decompiler.DebugInfo;
 using ICSharpCode.Decompiler.Metadata;
 
+#nullable enable
+
 namespace ICSharpCode.ILSpyX.PdbProvider
 {
 	public static class DebugInfoUtils
 	{
-		public static IDebugInfoProvider LoadSymbols(PEFile module)
+		public static IDebugInfoProvider? LoadSymbols(PEFile module)
 		{
 			try
 			{
 				// try to open portable pdb file/embedded pdb info:
 				if (TryOpenPortablePdb(module, out var provider, out var pdbFileName))
 				{
-					return new PortableDebugInfoProvider(pdbFileName, provider, module.FileName);
+					return new PortableDebugInfoProvider(module.FileName, provider, pdbFileName);
 				}
 				else
 				{
 					// search for pdb in same directory as dll
 					pdbFileName = Path.Combine(
-						Path.GetDirectoryName(module.FileName),
+						Path.GetDirectoryName(module.FileName)!,
 						Path.GetFileNameWithoutExtension(module.FileName) + ".pdb"
 					);
 					if (File.Exists(pdbFileName))
@@ -59,12 +61,12 @@ namespace ICSharpCode.ILSpyX.PdbProvider
 			return null;
 		}
 
-		public static IDebugInfoProvider FromFile(PEFile module, string pdbFileName)
+		public static IDebugInfoProvider? FromFile(PEFile module, string pdbFileName)
 		{
 			if (string.IsNullOrEmpty(pdbFileName))
 				return null;
 
-			Stream stream = OpenStream(pdbFileName);
+			Stream? stream = OpenStream(pdbFileName);
 			if (stream == null)
 				return null;
 
@@ -78,7 +80,7 @@ namespace ICSharpCode.ILSpyX.PdbProvider
 			{
 				stream.Position = 0;
 				var provider = MetadataReaderProvider.FromPortablePdbStream(stream);
-				return new PortableDebugInfoProvider(pdbFileName, provider, module.FileName);
+				return new PortableDebugInfoProvider(module.FileName, provider, pdbFileName);
 			}
 		}
 
@@ -86,7 +88,8 @@ namespace ICSharpCode.ILSpyX.PdbProvider
 		static readonly byte[] buffer = new byte[LegacyPDBPrefix.Length];
 
 		static bool TryOpenPortablePdb(PEFile module,
-			out MetadataReaderProvider provider, out string pdbFileName)
+			[NotNullWhen(true)] out MetadataReaderProvider? provider,
+			[NotNullWhen(true)] out string? pdbFileName)
 		{
 			provider = null;
 			pdbFileName = null;
@@ -100,12 +103,12 @@ namespace ICSharpCode.ILSpyX.PdbProvider
 				}
 				if (entry.Type == DebugDirectoryEntryType.CodeView)
 				{
-					string pdbDirectory = Path.GetDirectoryName(module.FileName);
+					string pdbDirectory = Path.GetDirectoryName(module.FileName)!;
 					pdbFileName = Path.Combine(
 						pdbDirectory, Path.GetFileNameWithoutExtension(module.FileName) + ".pdb");
-					if (File.Exists(pdbFileName))
+					Stream? stream = OpenStream(pdbFileName);
+					if (stream != null)
 					{
-						Stream stream = OpenStream(pdbFileName);
 						if (stream.Read(buffer, 0, buffer.Length) == LegacyPDBPrefix.Length
 							&& System.Text.Encoding.ASCII.GetString(buffer) == LegacyPDBPrefix)
 						{
@@ -120,7 +123,7 @@ namespace ICSharpCode.ILSpyX.PdbProvider
 			return false;
 		}
 
-		static Stream OpenStream(string fileName)
+		static Stream? OpenStream(string fileName)
 		{
 			if (!File.Exists(fileName))
 				return null;

ICSharpCode.ILSpyX/PdbProvider/MonoCecilDebugInfoProvider.cs

@@ -18,6 +18,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Linq;
 using System.Reflection.Metadata.Ecma335;
@@ -31,13 +32,15 @@ using Mono.Cecil.Pdb;
 
 using SRM = System.Reflection.Metadata;
 
+#nullable enable
+
 namespace ICSharpCode.ILSpyX.PdbProvider
 {
 	public class MonoCecilDebugInfoProvider : IDebugInfoProvider
 	{
 		readonly Dictionary<SRM.MethodDefinitionHandle, (IList<SequencePoint> SequencePoints, IList<Variable> Variables)> debugInfo;
 
-		public unsafe MonoCecilDebugInfoProvider(PEFile module, string pdbFileName, string description = null)
+		public unsafe MonoCecilDebugInfoProvider(PEFile module, string pdbFileName, string? description = null)
 		{
 			if (module == null)
 			{
@@ -49,8 +52,8 @@ namespace ICSharpCode.ILSpyX.PdbProvider
 				throw new ArgumentException("This provider needs access to the full image!");
 			}
 
+			this.SourceFileName = pdbFileName ?? throw new ArgumentNullException(nameof(pdbFileName));
 			this.Description = description ?? $"Loaded from PDB file: {pdbFileName}";
-			this.SourceFileName = pdbFileName;
 
 			var image = module.Reader.GetEntireImage();
 			this.debugInfo = new Dictionary<SRM.MethodDefinitionHandle, (IList<SequencePoint> SequencePoints, IList<Variable> Variables)>();
@@ -120,7 +123,7 @@ namespace ICSharpCode.ILSpyX.PdbProvider
 			return info.Variables;
 		}
 
-		public bool TryGetName(SRM.MethodDefinitionHandle handle, int index, out string name)
+		public bool TryGetName(SRM.MethodDefinitionHandle handle, int index, [NotNullWhen(true)] out string? name)
 		{
 			name = null;
 			if (!debugInfo.TryGetValue(handle, out var info))

ICSharpCode.ILSpyX/PdbProvider/PortableDebugInfoProvider.cs

@@ -18,28 +18,32 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Reflection.Metadata;
 
 using ICSharpCode.Decompiler.DebugInfo;
+using ICSharpCode.Decompiler.Util;
+
+#nullable enable
 
 namespace ICSharpCode.ILSpyX.PdbProvider
 {
 	class PortableDebugInfoProvider : IDebugInfoProvider
 	{
-		string pdbFileName;
+		string? pdbFileName;
 		string moduleFileName;
 		readonly MetadataReaderProvider provider;
 		bool hasError;
 
 		internal bool IsEmbedded => pdbFileName == null;
 
-		public PortableDebugInfoProvider(string pdbFileName, MetadataReaderProvider provider,
-			string moduleFileName)
+		public PortableDebugInfoProvider(string moduleFileName, MetadataReaderProvider provider,
+			string? pdbFileName = null)
 		{
-			this.pdbFileName = pdbFileName;
-			this.moduleFileName = moduleFileName;
+			this.moduleFileName = moduleFileName ?? throw new ArgumentNullException(nameof(moduleFileName));
 			this.provider = provider ?? throw new ArgumentNullException(nameof(provider));
+			this.pdbFileName = pdbFileName;
 		}
 
 		public string Description {
@@ -59,7 +63,7 @@ namespace ICSharpCode.ILSpyX.PdbProvider
 			}
 		}
 
-		internal MetadataReader GetMetadataReader()
+		internal MetadataReader? GetMetadataReader()
 		{
 			try
 			{
@@ -83,10 +87,10 @@ namespace ICSharpCode.ILSpyX.PdbProvider
 		public IList<Decompiler.DebugInfo.SequencePoint> GetSequencePoints(MethodDefinitionHandle method)
 		{
 			var metadata = GetMetadataReader();
+			if (metadata == null)
+				return EmptyList<Decompiler.DebugInfo.SequencePoint>.Instance;
 			var debugInfo = metadata.GetMethodDebugInformation(method);
 			var sequencePoints = new List<Decompiler.DebugInfo.SequencePoint>();
-			if (metadata == null)
-				return sequencePoints;
 
 			foreach (var point in debugInfo.GetSequencePoints())
 			{
@@ -135,7 +139,7 @@ namespace ICSharpCode.ILSpyX.PdbProvider
 			return variables;
 		}
 
-		public bool TryGetName(MethodDefinitionHandle method, int index, out string name)
+		public bool TryGetName(MethodDefinitionHandle method, int index, [NotNullWhen(true)] out string? name)
 		{
 			var metadata = GetMetadataReader();
 			name = null;