Fix nullable and other warnings.

ICSharpCode.Decompiler.Tests/TestCases/Pretty/Async.cs

@@ -193,7 +193,9 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			catch (Exception ex)
 			{
 				await Task.Delay(0);
+#pragma warning disable CA2200 // Rethrow to preserve stack details
 				throw ex;
+#pragma warning restore CA2200 // Rethrow to preserve stack details
 			}
 		}
 

ICSharpCode.Decompiler.Tests/TestCases/Pretty/ExceptionHandling.cs

@@ -480,7 +480,9 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			catch (Exception ex) when (ex.Data.IsFixedSize)
 			{
 				Console.WriteLine(ex.ToString());
+#pragma warning disable CA2200 // Rethrow to preserve stack details
 				throw ex;
+#pragma warning restore CA2200 // Rethrow to preserve stack details
 			}
 		}
 
@@ -493,7 +495,9 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			catch (Exception ex) when (ex is InternalBufferOverflowException)
 			{
 				Console.WriteLine(ex.ToString());
+#pragma warning disable CA2200 // Rethrow to preserve stack details
 				throw ex;
+#pragma warning restore CA2200 // Rethrow to preserve stack details
 			}
 		}
 #endif

ICSharpCode.Decompiler.Tests/TestCases/Pretty/PInvoke.cs

@@ -53,6 +53,7 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			public int bottom;
 		}
 
+#pragma warning disable CS0618 // Type or member is obsolete
 		public static decimal MarshalAttributesOnPropertyAccessors {
 			[return: MarshalAs(UnmanagedType.Currency)]
 			get {
@@ -62,6 +63,7 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			set {
 			}
 		}
+#pragma warning restore CS0618 // Type or member is obsolete
 
 		[DllImport("xyz.dll", CharSet = CharSet.Auto)]
 		[return: MarshalAs(UnmanagedType.Bool)]

ICSharpCode.Decompiler/Metadata/UniversalAssemblyResolver.cs

@@ -217,7 +217,9 @@ namespace ICSharpCode.Decompiler.Metadata
 
 		public PEFile? ResolveModule(PEFile mainModule, string moduleName)
 		{
-			string baseDirectory = Path.GetDirectoryName(mainModule.FileName);
+			string? baseDirectory = Path.GetDirectoryName(mainModule.FileName);
+			if (baseDirectory == null)
+				return null;
 			string moduleFileName = Path.Combine(baseDirectory, moduleName);
 			return CreatePEFileFromFileName(moduleFileName, ex => new ResolutionException(mainModule.FileName, moduleName, moduleFileName, ex));
 		}
@@ -381,7 +383,7 @@ namespace ICSharpCode.Decompiler.Metadata
 			return null;
 		}
 
-		string FindClosestVersionDirectory(string? basePath, Version? version)
+		string FindClosestVersionDirectory(string basePath, Version? version)
 		{
 			string? path = null;
 			foreach (var folder in new DirectoryInfo(basePath).GetDirectories().Select(d => DotNetCorePathFinder.ConvertToVersion(d.Name))
@@ -402,7 +404,7 @@ namespace ICSharpCode.Decompiler.Metadata
 			if (assembly != null)
 				return assembly;
 
-			var framework_dir = Path.GetDirectoryName(typeof(object).Module.FullyQualifiedName);
+			var framework_dir = Path.GetDirectoryName(typeof(object).Module.FullyQualifiedName)!;
 			var framework_dirs = decompilerRuntime == DecompilerRuntime.Mono
 				? new[] { framework_dir, Path.Combine(framework_dir, "Facades") }
 				: new[] { framework_dir };
@@ -444,6 +446,8 @@ namespace ICSharpCode.Decompiler.Metadata
 		{
 			foreach (var directory in directories)
 			{
+				if (directory == null)
+					continue;
 				string? file = SearchDirectory(name, directory);
 				if (file != null)
 					return file;
@@ -457,7 +461,7 @@ namespace ICSharpCode.Decompiler.Metadata
 			return IsZeroOrAllOnes(reference.Version) || reference.IsRetargetable;
 		}
 
-		string? SearchDirectory(IAssemblyReference name, string? directory)
+		string? SearchDirectory(IAssemblyReference name, string directory)
 		{
 			var extensions = name.IsWindowsRuntime ? new[] { ".winmd", ".dll" } : new[] { ".dll", ".exe" };
 			foreach (var extension in extensions)
@@ -581,7 +585,7 @@ namespace ICSharpCode.Decompiler.Metadata
 
 		string? GetMonoMscorlibBasePath(Version version)
 		{
-			var path = Directory.GetParent(typeof(object).Module.FullyQualifiedName).Parent.FullName;
+			var path = Directory.GetParent(typeof(object).Module.FullyQualifiedName)!.Parent!.FullName;
 			if (version.Major == 1)
 				path = Path.Combine(path, "1.0");
 			else if (version.Major == 2)
@@ -646,7 +650,7 @@ namespace ICSharpCode.Decompiler.Metadata
 		{
 			return Path.Combine(
 				Directory.GetParent(
-					Path.GetDirectoryName(typeof(object).Module.FullyQualifiedName)).FullName,
+					Path.GetDirectoryName(typeof(object).Module.FullyQualifiedName)!)!.FullName,
 				"gac");
 		}
 
@@ -693,7 +697,7 @@ namespace ICSharpCode.Decompiler.Metadata
 			return null;
 		}
 
-		static string GetAssemblyFile(IAssemblyReference reference, string? prefix, string? gac)
+		static string GetAssemblyFile(IAssemblyReference reference, string prefix, string gac)
 		{
 			var gac_folder = new StringBuilder()
 				.Append(prefix)
@@ -719,8 +723,8 @@ namespace ICSharpCode.Decompiler.Metadata
 						continue;
 					foreach (var item in new DirectoryInfo(rootPath).EnumerateFiles("*.dll", SearchOption.AllDirectories))
 					{
-						string[] name = Path.GetDirectoryName(item.FullName).Substring(rootPath.Length + 1).Split(new[] { "\\" }, StringSplitOptions.RemoveEmptyEntries);
-						if (name.Length != 2)
+						string[]? name = Path.GetDirectoryName(item.FullName)?.Substring(rootPath.Length + 1).Split(new[] { "\\" }, StringSplitOptions.RemoveEmptyEntries);
+						if (name?.Length != 2)
 							continue;
 						var match = Regex.Match(name[1], $"(v4.0_)?(?<version>[^_]+)_(?<culture>[^_]+)?_(?<publicKey>[^_]+)");
 						if (!match.Success)

ICSharpCode.Decompiler/Util/CollectionExtensions.cs

@@ -15,7 +15,7 @@ namespace ICSharpCode.Decompiler.Util
 		}
 
 #if !NETCORE
-		public static IEnumerable<(A, B)> Zip<A, B>(this IEnumerable<A>? input1, IEnumerable<B>? input2)
+		public static IEnumerable<(A, B)> Zip<A, B>(this IEnumerable<A> input1, IEnumerable<B> input2)
 		{
 			return input1.Zip(input2, (a, b) => (a, b));
 		}
@@ -61,7 +61,7 @@ namespace ICSharpCode.Decompiler.Util
 		}
 
 #if !NETCORE
-		public static HashSet<T> ToHashSet<T>(this IEnumerable<T>? input)
+		public static HashSet<T> ToHashSet<T>(this IEnumerable<T> input)
 		{
 			return new HashSet<T>(input);
 		}
@@ -354,7 +354,7 @@ namespace ICSharpCode.Decompiler.Util
 			list.RemoveAt(list.Count - 1);
 		}
 
-		public static T? OnlyOrDefault<T>(this IEnumerable<T>? source, Func<T, bool>? predicate) => OnlyOrDefault(source.Where(predicate));
+		public static T? OnlyOrDefault<T>(this IEnumerable<T> source, Func<T, bool> predicate) => OnlyOrDefault(source.Where(predicate));
 
 		public static T? OnlyOrDefault<T>(this IEnumerable<T> source)
 		{
@@ -373,14 +373,14 @@ namespace ICSharpCode.Decompiler.Util
 
 		#region Aliases/shortcuts for Enumerable extension methods
 		public static bool Any<T>(this ICollection<T> list) => list.Count > 0;
-		public static bool Any<T>(this T[]? array, Predicate<T>? match) => Array.Exists(array, match);
-		public static bool Any<T>(this List<T> list, Predicate<T>? match) => list.Exists(match);
+		public static bool Any<T>(this T[] array, Predicate<T> match) => Array.Exists(array, match);
+		public static bool Any<T>(this List<T> list, Predicate<T> match) => list.Exists(match);
 
-		public static bool All<T>(this T[]? array, Predicate<T>? match) => Array.TrueForAll(array, match);
-		public static bool All<T>(this List<T> list, Predicate<T>? match) => list.TrueForAll(match);
+		public static bool All<T>(this T[] array, Predicate<T> match) => Array.TrueForAll(array, match);
+		public static bool All<T>(this List<T> list, Predicate<T> match) => list.TrueForAll(match);
 
-		public static T FirstOrDefault<T>(this T[]? array, Predicate<T>? predicate) => Array.Find(array, predicate);
-		public static T FirstOrDefault<T>(this List<T> list, Predicate<T>? predicate) => list.Find(predicate);
+		public static T? FirstOrDefault<T>(this T[] array, Predicate<T> predicate) => Array.Find(array, predicate);
+		public static T? FirstOrDefault<T>(this List<T> list, Predicate<T> predicate) => list.Find(predicate);
 
 		public static T Last<T>(this IList<T> list) => list[list.Count - 1];
 		#endregion

ICSharpCode.Decompiler/Util/KeyComparer.cs

@@ -69,12 +69,12 @@ namespace ICSharpCode.Decompiler.Util
 			this.keyEqualityComparer = keyEqualityComparer;
 		}
 
-		public int Compare(TElement x, TElement y)
+		public int Compare(TElement? x, TElement? y)
 		{
 			return keyComparer.Compare(keySelector(x), keySelector(y));
 		}
 
-		public bool Equals(TElement x, TElement y)
+		public bool Equals(TElement? x, TElement? y)
 		{
 			return keyEqualityComparer.Equals(keySelector(x), keySelector(y));
 		}

ICSharpCode.Decompiler/Util/LongSet.cs

@@ -83,7 +83,7 @@ namespace ICSharpCode.Decompiler.Util
 		/// <summary>
 		/// Creates a new LongSet the contains the values from the specified intervals.
 		/// </summary>
-		public LongSet(IEnumerable<LongInterval>? intervals)
+		public LongSet(IEnumerable<LongInterval> intervals)
 			: this(MergeOverlapping(intervals.Where(i => !i.IsEmpty).OrderBy(i => i.Start)).ToImmutableArray())
 		{
 		}

ICSharpCode.Decompiler/Util/MultiDictionary.cs

@@ -25,7 +25,7 @@ namespace ICSharpCode.Decompiler.Util
 	/// <summary>
 	/// A dictionary that allows multiple pairs with the same key.
 	/// </summary>
-	public class MultiDictionary<TKey, TValue> : ILookup<TKey, TValue>
+	public class MultiDictionary<TKey, TValue> : ILookup<TKey, TValue> where TKey : notnull
 	{
 		readonly Dictionary<TKey, List<TValue>> dict;
 
@@ -41,8 +41,7 @@ namespace ICSharpCode.Decompiler.Util
 
 		public void Add(TKey key, TValue value)
 		{
-			List<TValue> valueList;
-			if (!dict.TryGetValue(key, out valueList))
+			if (!dict.TryGetValue(key, out List<TValue>? valueList))
 			{
 				valueList = new List<TValue>();
 				dict.Add(key, valueList);
@@ -52,8 +51,7 @@ namespace ICSharpCode.Decompiler.Util
 
 		public bool Remove(TKey key, TValue value)
 		{
-			List<TValue> valueList;
-			if (dict.TryGetValue(key, out valueList))
+			if (dict.TryGetValue(key, out List<TValue>? valueList))
 			{
 				if (valueList.Remove(value))
 				{

ICSharpCode.Decompiler/Util/UnionFind.cs

@@ -24,7 +24,7 @@ namespace ICSharpCode.Decompiler.Util
 	/// <summary>
 	/// Union-Find data structure.
 	/// </summary>
-	public class UnionFind<T>
+	public class UnionFind<T> where T : notnull
 	{
 		Dictionary<T, Node> mapping;
 
@@ -48,8 +48,7 @@ namespace ICSharpCode.Decompiler.Util
 
 		Node GetNode(T element)
 		{
-			Node node;
-			if (!mapping.TryGetValue(element, out node))
+			if (!mapping.TryGetValue(element, out Node? node))
 			{
 				node = new Node(element);
 				node.parent = node;

ILSpy/Analyzers/Builtin/FindTypeInAttributeDecoder.cs

@@ -65,7 +65,7 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 		public FindTypeInAttributeDecoder(MetadataModule currentModule, ITypeDefinition type)
 		{
 			this.currentModule = currentModule;
-			this.declaringModule = type.ParentModule.PEFile ?? throw new InvalidOperationException("Cannot use MetadataModule without PEFile as context.");
+			this.declaringModule = type.ParentModule?.PEFile ?? throw new InvalidOperationException("Cannot use MetadataModule without PEFile as context.");
 			this.handle = (TypeDefinitionHandle)type.MetadataToken;
 			this.primitiveType = type.KnownTypeCode == KnownTypeCode.None ? 0 : type.KnownTypeCode.ToPrimitiveTypeCode();
 		}
@@ -138,7 +138,7 @@ namespace ICSharpCode.ILSpy.Analyzers.Builtin
 			{
 				result = TokenSearchResult.SystemType;
 			}
-			if (td.MetadataToken == this.handle && td.ParentModule.PEFile == declaringModule)
+			if (td.MetadataToken == this.handle && td.ParentModule?.PEFile == declaringModule)
 			{
 				result |= TokenSearchResult.Found;
 			}

ILSpy/Languages/CSharpLexer.cs

@@ -107,7 +107,7 @@ namespace ICSharpCode.ILSpy
 		}
 	}
 
-	internal abstract class AbstractLexer
+	internal abstract class AbstractLexer : IDisposable
 	{
 		LATextReader reader;
 		int col = 1;