Add support for decoding `NativeIntegerAttribute`.

ICSharpCode.Decompiler/CSharp/CSharpLanguageVersion.cs

@@ -17,6 +17,7 @@ namespace ICSharpCode.Decompiler.CSharp
 		CSharp7_2 = 702,
 		CSharp7_3 = 703,
 		CSharp8_0 = 800,
+		CSharp9_0 = 900,
 		Latest = 0x7FFFFFFF
 	}
 }

ICSharpCode.Decompiler/CSharp/Syntax/TypeSystemAstBuilder.cs

@@ -248,6 +248,12 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 
 		AstType ConvertTypeHelper(IType type)
 		{
+			switch (type.Kind) {
+				case TypeKind.Dynamic:
+				case TypeKind.NInt:
+				case TypeKind.NUInt:
+					return new PrimitiveType(type.Name);
+			}
 			if (type is TypeWithElementType typeWithElementType) {
 				if (typeWithElementType is PointerType) {
 					return ConvertType(typeWithElementType.ElementType).MakePointerType();

ICSharpCode.Decompiler/DecompilerSettings.cs

@@ -114,10 +114,15 @@ namespace ICSharpCode.Decompiler
 				staticLocalFunctions = false;
 				ranges = false;
 			}
+			if (languageVersion < CSharp.LanguageVersion.CSharp9_0) {
+				nativeIntegers = false;
+			}
 		}
 
 		public CSharp.LanguageVersion GetMinimumRequiredVersion()
 		{
+			if (nativeIntegers)
+				return CSharp.LanguageVersion.CSharp9_0;
 			if (nullableReferenceTypes || readOnlyMethods || asyncEnumerator || asyncUsingAndForEachStatement || staticLocalFunctions || ranges)
 				return CSharp.LanguageVersion.CSharp8_0;
 			if (introduceUnmanagedConstraint || tupleComparisons || stackAllocInitializers || patternBasedFixedStatement)
@@ -141,6 +146,23 @@ namespace ICSharpCode.Decompiler
 			return CSharp.LanguageVersion.CSharp1;
 		}
 
+		bool nativeIntegers = true;
+
+		/// <summary>
+		/// Use C# 9 <c>nint</c>/<c>nuint</c> types.
+		/// </summary>
+		[Category("C# 9.0 (experimental)")]
+		[Description("DecompilerSettings.NativeIntegers")]
+		public bool NativeIntegers {
+			get { return nativeIntegers; }
+			set {
+				if (nativeIntegers != value) {
+					nativeIntegers = value;
+					OnPropertyChanged();
+				}
+			}
+		}
+
 		bool anonymousMethods = true;
 
 		/// <summary>

ICSharpCode.Decompiler/TypeSystem/ApplyAttributeTypeVisitor.cs

@@ -42,6 +42,8 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		{
 			bool hasDynamicAttribute = false;
 			bool[] dynamicAttributeData = null;
+			bool hasNativeIntegersAttribute = false;
+			bool[] nativeIntegersAttributeData = null;
 			string[] tupleElementNames = null;
 			Nullability nullability;
 			Nullability[] nullableAttributeData = null;
@@ -50,7 +52,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 			} else {
 				nullability = Nullability.Oblivious;
 			}
-			const TypeSystemOptions relevantOptions = TypeSystemOptions.Dynamic | TypeSystemOptions.Tuple | TypeSystemOptions.NullabilityAnnotations;
+			const TypeSystemOptions relevantOptions = TypeSystemOptions.Dynamic | TypeSystemOptions.Tuple | TypeSystemOptions.NullabilityAnnotations | TypeSystemOptions.NativeIntegers;
 			if (attributes != null && (options & relevantOptions) != 0) {
 				foreach (var attrHandle in attributes.Value) {
 					var attr = metadata.GetCustomAttribute(attrHandle);
@@ -65,6 +67,16 @@ namespace ICSharpCode.Decompiler.TypeSystem
 								dynamicAttributeData = values.SelectArray(v => (bool)v.Value);
 							}
 						}
+					} else if ((options & TypeSystemOptions.NativeIntegers) != 0 && attrType.IsKnownType(metadata, KnownAttribute.NativeInteger)) {
+						hasNativeIntegersAttribute = true;
+						var ctor = attr.DecodeValue(Metadata.MetadataExtensions.minimalCorlibTypeProvider);
+						if (ctor.FixedArguments.Length == 1) {
+							var arg = ctor.FixedArguments[0];
+							if (arg.Value is ImmutableArray<SRM.CustomAttributeTypedArgument<IType>> values
+								&& values.All(v => v.Value is bool)) {
+								nativeIntegersAttributeData = values.SelectArray(v => (bool)v.Value);
+							}
+						}
 					} else if ((options & TypeSystemOptions.Tuple) != 0 && attrType.IsKnownType(metadata, KnownAttribute.TupleElementNames)) {
 						var ctor = attr.DecodeValue(Metadata.MetadataExtensions.minimalCorlibTypeProvider);
 						if (ctor.FixedArguments.Length == 1) {
@@ -88,11 +100,12 @@ namespace ICSharpCode.Decompiler.TypeSystem
 					}
 				}
 			}
-			if (hasDynamicAttribute || nullability != Nullability.Oblivious || nullableAttributeData != null 
+			if (hasDynamicAttribute || hasNativeIntegersAttribute || nullability != Nullability.Oblivious || nullableAttributeData != null 
 				|| (options & (TypeSystemOptions.Tuple | TypeSystemOptions.KeepModifiers)) != TypeSystemOptions.KeepModifiers)
 			{
 				var visitor = new ApplyAttributeTypeVisitor(
 					compilation, hasDynamicAttribute, dynamicAttributeData,
+					hasNativeIntegersAttribute, nativeIntegersAttributeData,
 					options, tupleElementNames,
 					nullability, nullableAttributeData
 				);
@@ -109,6 +122,8 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		readonly ICompilation compilation;
 		readonly bool hasDynamicAttribute;
 		readonly bool[] dynamicAttributeData;
+		readonly bool hasNativeIntegersAttribute;
+		readonly bool[] nativeIntegersAttributeData;
 		readonly TypeSystemOptions options;
 		readonly string[] tupleElementNames;
 		readonly Nullability defaultNullability;
@@ -117,12 +132,17 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		int tupleTypeIndex = 0;
 		int nullabilityTypeIndex = 0;
 
-		private ApplyAttributeTypeVisitor(ICompilation compilation, bool hasDynamicAttribute, bool[] dynamicAttributeData, TypeSystemOptions options, string[] tupleElementNames,
+		private ApplyAttributeTypeVisitor(ICompilation compilation, 
+			bool hasDynamicAttribute, bool[] dynamicAttributeData,
+			bool hasNativeIntegersAttribute, bool[] nativeIntegersAttributeData,
+			TypeSystemOptions options, string[] tupleElementNames,
 			Nullability defaultNullability, Nullability[] nullableAttributeData)
 		{
 			this.compilation = compilation ?? throw new ArgumentNullException(nameof(compilation));
 			this.hasDynamicAttribute = hasDynamicAttribute;
 			this.dynamicAttributeData = dynamicAttributeData;
+			this.hasNativeIntegersAttribute = hasNativeIntegersAttribute;
+			this.nativeIntegersAttributeData = nativeIntegersAttributeData;
 			this.options = options;
 			this.tupleElementNames = tupleElementNames;
 			this.defaultNullability = defaultNullability;
@@ -247,11 +267,18 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		public override IType VisitTypeDefinition(ITypeDefinition type)
 		{
 			IType newType = type;
-			if (type.KnownTypeCode == KnownTypeCode.Object && hasDynamicAttribute) {
+			var ktc = type.KnownTypeCode;
+			if (ktc == KnownTypeCode.Object && hasDynamicAttribute) {
 				if (dynamicAttributeData == null || dynamicTypeIndex >= dynamicAttributeData.Length)
 					newType = SpecialType.Dynamic;
 				else if (dynamicAttributeData[dynamicTypeIndex])
 					newType = SpecialType.Dynamic;
+			} else if ((ktc == KnownTypeCode.IntPtr || ktc == KnownTypeCode.UIntPtr) && hasNativeIntegersAttribute) {
+				// native integers use the same indexing logic as 'dynamic'
+				if (nativeIntegersAttributeData == null || dynamicTypeIndex > nativeIntegersAttributeData.Length)
+					newType = (ktc == KnownTypeCode.IntPtr ? SpecialType.NInt : SpecialType.NUInt);
+				else if (nativeIntegersAttributeData[dynamicTypeIndex])
+					newType = (ktc == KnownTypeCode.IntPtr ? SpecialType.NInt : SpecialType.NUInt);
 			}
 			if (type.IsReferenceType == true) {
 				Nullability nullability = GetNullability();

ICSharpCode.Decompiler/TypeSystem/DecompilerTypeSystem.cs

@@ -110,10 +110,15 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		/// </summary>
 		ReadOnlyMethods = 0x800,
 		/// <summary>
+		/// [NativeIntegerAttribute] is used to replace 'IntPtr' types with the 'nint' type.
+		/// </summary>
+		NativeIntegers = 0x1000,
+		/// <summary>
 		/// Default settings: typical options for the decompiler, with all C# languages features enabled.
 		/// </summary>
 		Default = Dynamic | Tuple | ExtensionMethods | DecimalConstants | ReadOnlyStructsAndParameters
 			| RefStructs | UnmanagedConstraints | NullabilityAnnotations | ReadOnlyMethods
+			| NativeIntegers
 	}
 
 	/// <summary>
@@ -145,6 +150,8 @@ namespace ICSharpCode.Decompiler.TypeSystem
 				typeSystemOptions |= TypeSystemOptions.NullabilityAnnotations;
 			if (settings.ReadOnlyMethods)
 				typeSystemOptions |= TypeSystemOptions.ReadOnlyMethods;
+			if (settings.NativeIntegers)
+				typeSystemOptions |= TypeSystemOptions.NativeIntegers;
 			return typeSystemOptions;
 		}
 

ICSharpCode.Decompiler/TypeSystem/Implementation/AttributeListBuilder.cs

@@ -194,6 +194,8 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 					switch (attributeType.Name) {
 						case "DynamicAttribute":
 							return (options & TypeSystemOptions.Dynamic) != 0;
+						case "NativeIntegerAttribute":
+							return (options & TypeSystemOptions.NativeIntegers) != 0;
 						case "TupleElementNamesAttribute":
 							return (options & TypeSystemOptions.Tuple) != 0;
 						case "ExtensionAttribute":

ICSharpCode.Decompiler/TypeSystem/Implementation/KnownAttributes.cs

@@ -98,11 +98,14 @@ namespace ICSharpCode.Decompiler.TypeSystem
 
 		// Security attributes:
 		PermissionSet,
+
+		// C# 9 attributes:
+		NativeInteger,
 	}
 
 	static class KnownAttributes
 	{
-		internal const int Count = (int)KnownAttribute.PermissionSet + 1;
+		internal const int Count = (int)KnownAttribute.NativeInteger + 1;
 
 		static readonly TopLevelTypeName[] typeNames = new TopLevelTypeName[Count]{
 			default,
@@ -160,6 +163,8 @@ namespace ICSharpCode.Decompiler.TypeSystem
 			new TopLevelTypeName("System.Runtime.InteropServices", nameof(MarshalAsAttribute)),
 			// Security attributes:
 			new TopLevelTypeName("System.Security.Permissions", "PermissionSetAttribute"),
+			// C# 9 attributes:
+			new TopLevelTypeName("System.Runtime.CompilerServices", "NativeIntegerAttribute"),
 		};
 
 		public static ref readonly TopLevelTypeName GetTypeName(this KnownAttribute attr)

ICSharpCode.Decompiler/TypeSystem/TypeUtils.cs

@@ -36,6 +36,8 @@ namespace ICSharpCode.Decompiler.TypeSystem
 				case TypeKind.Pointer:
 				case TypeKind.ByReference:
 				case TypeKind.Class:
+				case TypeKind.NInt:
+				case TypeKind.NUInt:
 					return NativeIntSize;
 				case TypeKind.Enum:
 					type = type.GetEnumUnderlyingType();
@@ -243,6 +245,8 @@ namespace ICSharpCode.Decompiler.TypeSystem
 				case TypeKind.ByReference:
 					return StackType.Ref;
 				case TypeKind.Pointer:
+				case TypeKind.NInt:
+				case TypeKind.NUInt:
 					return StackType.I;
 				case TypeKind.TypeParameter:
 					// Type parameters are always considered StackType.O, even
@@ -305,8 +309,13 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		public static Sign GetSign(this IType type)
 		{
 			type = type.SkipModifiers();
-			if (type.Kind == TypeKind.Pointer)
-				return Sign.Unsigned;
+			switch (type.Kind) {
+				case TypeKind.Pointer:
+				case TypeKind.NUInt:
+					return Sign.Unsigned;
+				case TypeKind.NInt:
+					return Sign.Signed;
+			}
 			var typeDef = type.GetEnumUnderlyingType().GetDefinition();
 			if (typeDef == null)
 				return Sign.None;
@@ -375,8 +384,12 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		public static PrimitiveType ToPrimitiveType(this IType type)
 		{
 			type = type.SkipModifiers();
-			if (type.Kind == TypeKind.Unknown) return PrimitiveType.Unknown;
-			if (type.Kind == TypeKind.ByReference) return PrimitiveType.Ref;
+			switch (type.Kind) {
+				case TypeKind.Unknown: return PrimitiveType.Unknown;
+				case TypeKind.ByReference: return PrimitiveType.Ref;
+				case TypeKind.NInt: return PrimitiveType.I;
+				case TypeKind.NUInt: return PrimitiveType.U;
+			}
 			var def = type.GetEnumUnderlyingType().GetDefinition();
 			return def != null ? def.KnownTypeCode.ToPrimitiveType() : PrimitiveType.None;
 		}

ILSpy/Languages/CSharpHighlightingTokenWriter.cs

@@ -298,12 +298,15 @@ namespace ICSharpCode.ILSpy
 				case "ushort":
 				case "ulong":
 				case "unmanaged":
+				case "nint":
+				case "nuint":
 					color = valueTypeKeywordsColor;
 					break;
 				case "class":
 				case "object":
 				case "string":
 				case "void":
+				case "dynamic":
 					color = referenceTypeKeywordsColor;
 					break;
 			}
@@ -327,7 +330,7 @@ namespace ICSharpCode.ILSpy
 			{
 				color = valueKeywordColor;
 			}
-			if ((identifier.Name == "dynamic" || identifier.Name == "var") && identifier.Parent is AstType)
+			if (identifier.Name == "var" && identifier.Parent is AstType)
 				color = queryKeywordsColor;
 			switch (GetCurrentDefinition()) {
 				case ITypeDefinition t:

ILSpy/Languages/CSharpLanguage.cs

@@ -107,6 +107,7 @@ namespace ICSharpCode.ILSpy
 						new LanguageVersion(Decompiler.CSharp.LanguageVersion.CSharp7_2.ToString(), "C# 7.2 / VS 2017.4"),
 						new LanguageVersion(Decompiler.CSharp.LanguageVersion.CSharp7_3.ToString(), "C# 7.3 / VS 2017.7"),
 						new LanguageVersion(Decompiler.CSharp.LanguageVersion.CSharp8_0.ToString(), "C# 8.0 / VS 2019"),
+						new LanguageVersion(Decompiler.CSharp.LanguageVersion.CSharp9_0.ToString(), "C# 9.0 (experimental)"),
 					};
 				}
 				return versions;

ILSpy/Properties/Resources.Designer.cs

@@ -576,15 +576,6 @@ namespace ICSharpCode.ILSpy.Properties {
             }
         }
         
-        /// <summary>
-        ///   Looks up a localized string similar to Aggressively perform Scalar Replacement Of Aggregates (SROA).
-        /// </summary>
-        public static string DecompilerSettings_AggressiveScalarReplacementOfAggregates {
-            get {
-                return ResourceManager.GetString("DecompilerSettings.AggressiveScalarReplacementOfAggregates", resourceCulture);
-            }
-        }
-        
         /// <summary>
         ///   Looks up a localized string similar to Allow extension &apos;Add&apos; methods in collection initializer expressions.
         /// </summary>
@@ -920,6 +911,15 @@ namespace ICSharpCode.ILSpy.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Use nint/nuint types.
+        /// </summary>
+        public static string DecompilerSettings_NativeIntegers {
+            get {
+                return ResourceManager.GetString("DecompilerSettings.NativeIntegers", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Nullable reference types.
         /// </summary>

ILSpy/Properties/Resources.resx

@@ -873,4 +873,7 @@ Do you want to continue?</value>
   <data name="DecompilerSettings.UseSdkStyleProjectFormat" xml:space="preserve">
     <value>Use new SDK style format for generated project files (*.csproj)</value>
   </data>
+  <data name="DecompilerSettings.NativeIntegers" xml:space="preserve">
+    <value>Use nint/nuint types</value>
+  </data>
 </root>