Create shared WellKnownTypes enum

src/ILLink.RoslynAnalyzer/COMAnalyzer.cs

@@ -6,6 +6,7 @@
 using System.Collections.Immutable;
 using System.Runtime.InteropServices;
 using ILLink.Shared;
+using ILLink.Shared.TypeSystemProxy;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Diagnostics;
 using Microsoft.CodeAnalysis.Operations;
@@ -88,11 +89,11 @@ static bool IsComInterop (ISymbol symbol)
 				if (typeSymbol == null)
 					return false;
 
-				if (typeSymbol.ContainingNamespace.Name == "System" && typeSymbol.Name == "Array") {
+				if (typeSymbol.IsTypeOf (WellKnownType.System_Array)) {
 					// System.Array marshals as IUnknown by default
 					return true;
-				} else if (typeSymbol.ContainingNamespace.Name == "System" && typeSymbol.Name == "String" ||
-					typeSymbol.ContainingNamespace.Name == "System.Text" && typeSymbol.Name == "StringBuilder") {
+				} else if (typeSymbol.IsTypeOf (WellKnownType.System_String) ||
+					typeSymbol.IsTypeOf ("System.Text", "StringBuilder")) {
 					// String and StringBuilder are special cased by interop
 					return false;
 				}
@@ -103,8 +104,7 @@ static bool IsComInterop (ISymbol symbol)
 				} else if (typeSymbol.IsInterface ()) {
 					// Interface types marshal as COM by default
 					return true;
-				} else if (typeSymbol.ContainingNamespace.Name == "System" &&
-					typeSymbol.Name == "MulticastDelegate") {
+				} else if (typeSymbol.IsTypeOf ("System", "MulticastDelegate")) {
 					// Delegates are special cased by interop
 					return false;
 				} else if (typeSymbol.IsSubclassOf ("System.Runtime.InteropServices", "CriticalHandle") ||

src/ILLink.RoslynAnalyzer/ISymbolExtensions.cs

@@ -113,7 +113,7 @@ public static string GetDisplayName (this ISymbol symbol)
 				// Use definition type parameter names, not instance type parameters
 				methodSymbol = methodSymbol.OriginalDefinition;
 				// Format the declaring type with namespace and containing types.
-				if (methodSymbol.ContainingSymbol.Kind == SymbolKind.NamedType) {
+				if (methodSymbol.ContainingSymbol?.Kind == SymbolKind.NamedType) {
 					// If the containing symbol is a method (for example for local functions),
 					// don't include the containing type's name. This matches the behavior of
 					// CSharpErrorMessageFormat.
@@ -147,8 +147,7 @@ public static bool IsSubclassOf (this ISymbol symbol, string ns, string type)
 				return false;
 
 			while (typeSymbol != null) {
-				if (typeSymbol.ContainingNamespace.Name == ns &&
-					typeSymbol.ContainingType.Name == type)
+				if (typeSymbol.IsTypeOf (ns, type))
 					return true;
 
 				typeSymbol = typeSymbol.ContainingType;

src/ILLink.RoslynAnalyzer/ITypeSymbolExtensions.cs

@@ -2,6 +2,8 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Diagnostics;
+using ILLink.Shared.TypeSystemProxy;
 using Microsoft.CodeAnalysis;
 
 namespace ILLink.RoslynAnalyzer
@@ -27,17 +29,17 @@ public static bool IsTypeInterestingForDataflow (this ITypeSymbol type)
 		private static HierarchyFlags GetFlags (ITypeSymbol type)
 		{
 			HierarchyFlags flags = 0;
-			if (type.Name == "IReflect" && type.ContainingNamespace.GetDisplayName () == "System.Reflection") {
+			if (type.IsTypeOf (WellKnownType.System_Reflection_IReflect)) {
 				flags |= HierarchyFlags.IsSystemReflectionIReflect;
 			}
 
 			ITypeSymbol? baseType = type;
 			while (baseType != null) {
-				if (baseType.Name == "Type" && baseType.ContainingNamespace.GetDisplayName () == "System")
+				if (baseType.IsTypeOf (WellKnownType.System_Type))
 					flags |= HierarchyFlags.IsSystemType;
 
 				foreach (var iface in baseType.Interfaces) {
-					if (iface.Name == "IReflect" && iface.ContainingNamespace.GetDisplayName () == "System.Reflection") {
+					if (iface.IsTypeOf (WellKnownType.System_Reflection_IReflect)) {
 						flags |= HierarchyFlags.IsSystemReflectionIReflect;
 					}
 				}
@@ -50,5 +52,21 @@ private static HierarchyFlags GetFlags (ITypeSymbol type)
 		private static bool IsSystemType (HierarchyFlags flags) => (flags & HierarchyFlags.IsSystemType) != 0;
 
 		private static bool IsSystemReflectionIReflect (HierarchyFlags flags) => (flags & HierarchyFlags.IsSystemReflectionIReflect) != 0;
+
+		public static bool IsTypeOf (this ITypeSymbol symbol, string @namespace, string name)
+		{
+			return symbol.ContainingNamespace?.GetDisplayName () == @namespace && symbol.MetadataName == name;
+		}
+
+		public static bool IsTypeOf (this ITypeSymbol symbol, WellKnownType wellKnownType)
+		{
+			if (wellKnownType.TryGetSpecialType (out var specialType)) {
+				// Make sure checking the special type is the same as checking the metadata string names.
+				Debug.Assert (symbol.IsTypeOf (wellKnownType.GetNamespace (), wellKnownType.GetName ()) == (symbol.SpecialType == specialType));
+				return symbol.SpecialType == specialType;
+			}
+			var (Namespace, Name) = wellKnownType.GetNamespaceAndName ();
+			return symbol.IsTypeOf (Namespace, Name);
+		}
 	}
 }

src/ILLink.RoslynAnalyzer/TrimAnalysis/TypeProxy.cs

@@ -14,12 +14,14 @@ internal readonly partial struct TypeProxy
 
 		public string Name { get => Type.MetadataName; }
 
-		public string Namespace { get => Type.ContainingNamespace.Name; }
+		public string? Namespace { get => Type.ContainingNamespace?.Name; }
+
+		public bool IsTypeOf (string @namespace, string name) => Type.IsTypeOf (@namespace, name);
+
+		public bool IsTypeOf (WellKnownType wellKnownType) => Type.IsTypeOf (wellKnownType);
 
 		public string GetDisplayName () => Type.GetDisplayName ();
 
 		public override string ToString () => Type.ToString ();
-
-		public bool IsTypeOf (string @namespace, string name) => Namespace == @namespace && Name == name;
 	}
 }

src/ILLink.RoslynAnalyzer/TrimAnalysis/WellKnownTypeExtensions.cs

@@ -0,0 +1,23 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.CodeAnalysis;
+
+namespace ILLink.Shared.TypeSystemProxy
+{
+	public static partial class WellKnownTypeExtensions
+	{
+		public static bool TryGetSpecialType (this WellKnownType wellKnownType, [NotNullWhen (true)] out SpecialType? specialType)
+		{
+			specialType = wellKnownType switch {
+				WellKnownType.System_String => SpecialType.System_String,
+				WellKnownType.System_Nullable_T => SpecialType.System_Nullable_T,
+				WellKnownType.System_Array => SpecialType.System_Array,
+				WellKnownType.System_Object => SpecialType.System_Object,
+				_ => null,
+			};
+			return specialType is not null;
+		}
+	}
+}

src/ILLink.Shared/TypeSystemProxy/WellKnownType.cs

@@ -0,0 +1,37 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+
+namespace ILLink.Shared.TypeSystemProxy
+{
+	public enum WellKnownType
+	{
+		System_String,
+		System_Nullable_T,
+		System_Type,
+		System_Reflection_IReflect,
+		System_Array,
+		System_Object,
+		System_Attribute
+	}
+
+	public static partial class WellKnownTypeExtensions
+	{
+		public static (string Namespace, string Name) GetNamespaceAndName (this WellKnownType type)
+		{
+			return type switch {
+				WellKnownType.System_String => ("System", "String"),
+				WellKnownType.System_Nullable_T => ("System", "Nullable`1"),
+				WellKnownType.System_Type => ("System", "Type"),
+				WellKnownType.System_Reflection_IReflect => ("System.Reflection", "IReflect"),
+				WellKnownType.System_Array => ("System", "Array"),
+				WellKnownType.System_Object => ("System", "Object"),
+				WellKnownType.System_Attribute => ("System", "Attribute"),
+				_ => throw new ArgumentException ($"{nameof (type)} is not a well-known type."),
+			};
+		}
+		public static string GetNamespace (this WellKnownType type) => GetNamespaceAndName (type).Namespace;
+		public static string GetName (this WellKnownType type) => GetNamespaceAndName (type).Name;
+	}
+}

src/linker/Linker.Dataflow/ReflectionMethodBodyScanner.cs

@@ -10,6 +10,7 @@
 using ILLink.Shared;
 using ILLink.Shared.DataFlow;
 using ILLink.Shared.TrimAnalysis;
+using ILLink.Shared.TypeSystemProxy;
 using Mono.Cecil;
 using Mono.Cecil.Cil;
 using Mono.Linker.Steps;
@@ -894,10 +895,10 @@ bool IsComInterop (IMarshalInfoProvider marshalInfoProvider, TypeReference param
 				var parameterTypeDef = _context.TryResolve (parameterType);
 
 				if (parameterTypeDef != null) {
-					if (parameterTypeDef.IsTypeOf ("System", "Array")) {
+					if (parameterTypeDef.IsTypeOf (WellKnownType.System_Array)) {
 						// System.Array marshals as IUnknown by default
 						return true;
-					} else if (parameterTypeDef.IsTypeOf ("System", "String") ||
+					} else if (parameterTypeDef.IsTypeOf (WellKnownType.System_String) ||
 						parameterTypeDef.IsTypeOf ("System.Text", "StringBuilder")) {
 						// String and StringBuilder are special cased by interop
 						return false;

src/linker/Linker.Dataflow/TypeProxy.cs

@@ -16,12 +16,14 @@ internal readonly partial struct TypeProxy
 
 		public string Name { get => Type.Name; }
 
-		public string Namespace { get => Type.Namespace; }
+		public string? Namespace { get => Type.Namespace; }
+
+		public bool IsTypeOf (string @namespace, string name) => Type.IsTypeOf (@namespace, name);
+
+		public bool IsTypeOf (WellKnownType wellKnownType) => Type.IsTypeOf (wellKnownType);
 
 		public string GetDisplayName () => Type.GetDisplayName ();
 
 		public override string ToString () => Type.ToString ();
-
-		public bool IsTypeOf (string @namespace, string name) => Type.IsTypeOf (@namespace, name);
 	}
 }

src/linker/Linker/TypeReferenceExtensions.cs

@@ -3,6 +3,7 @@
 using System.Diagnostics;
 using System.Linq;
 using System.Text;
+using ILLink.Shared.TypeSystemProxy;
 using Mono.Cecil;
 
 namespace Mono.Linker
@@ -358,6 +359,12 @@ public static bool IsTypeOf<T> (this TypeReference tr)
 			return tr.Name == type.Name && tr.Namespace == tr.Namespace;
 		}
 
+		public static bool IsTypeOf (this TypeReference tr, WellKnownType type)
+		{
+			var (@namespace, name) = type.GetNamespaceAndName ();
+			return tr.IsTypeOf (@namespace, name);
+		}
+
 		public static bool IsSubclassOf (this TypeReference type, string ns, string name, ITryResolveMetadata resolver)
 		{
 			TypeDefinition? baseType = resolver.TryResolve (type);