Fix ILLink behavior for modreq types

src/tools/illink/src/linker/Linker/TypeReferenceExtensions.cs

@@ -415,18 +415,26 @@ public static TypeReference WithoutModifiers (this TypeReference type)
 		// not an array, pointer, byref, or generic parameter. Conceptually this is supposed to represent the same idea as Roslyn's
 		// INamedTypeSymbol, or ILC's DefType/MetadataType.
 		public static bool IsNamedType (this TypeReference typeReference) {
+			if (typeReference.IsRequiredModifier)
+				typeReference = ((RequiredModifierType) typeReference).ElementType;
+			if (typeReference.IsOptionalModifier)
+				typeReference = ((OptionalModifierType) typeReference).ElementType;
+
 			if (typeReference.IsDefinition || typeReference.IsGenericInstance)
 				return true;
 
-			if (typeReference.IsArray || typeReference.IsByReference || typeReference.IsPointer || typeReference.IsGenericParameter)
+			if (typeReference.IsArray ||
+				typeReference.IsByReference ||
+				typeReference.IsPointer ||
+				typeReference.IsFunctionPointer ||
+				typeReference.IsGenericParameter)
 				return false;
 
 			// Shouldn't get called for these cases
-			Debug.Assert (!typeReference.IsFunctionPointer);
-			Debug.Assert (!typeReference.IsRequiredModifier);
-			Debug.Assert (!typeReference.IsOptionalModifier);
 			Debug.Assert (!typeReference.IsPinned);
 			Debug.Assert (!typeReference.IsSentinel);
+			if (typeReference.IsPinned || typeReference.IsSentinel)
+				return false;
 
 			Debug.Assert (typeReference.GetType () == typeof (TypeReference));
 			return true;

src/tools/illink/test/Mono.Linker.Tests.Cases/DataFlow/FieldDataFlow.cs

@@ -4,13 +4,15 @@
 using System;
 using System.Diagnostics.CodeAnalysis;
 using Mono.Linker.Tests.Cases.Expectations.Assertions;
+using Mono.Linker.Tests.Cases.Expectations.Metadata;
 using Mono.Linker.Tests.Cases.Expectations.Helpers;
 
 namespace Mono.Linker.Tests.Cases.DataFlow
 {
 	// Note: this test's goal is to validate that the product correctly reports unrecognized patterns
 	//   - so the main validation is done by the ExpectedWarning attributes.
 	[SkipKeptItemsValidation]
+	[SetupCompileArgument ("/unsafe")]
 	[ExpectedNoWarnings]
 	public class FieldDataFlow
 	{
@@ -31,6 +33,7 @@ public static void Main ()
 			instance.WriteToStaticFieldOnADifferentClass ();
 
 			instance.WriteUnknownValue ();
+			instance.WriteModReqType ();
 
 			WriteCapturedField.Test ();
 			WriteFieldOfCapturedInstance.Test ();
@@ -156,6 +159,16 @@ static void MakeArrayValuesUnknown (object[] array)
 			}
 		}
 
+		[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicFields)]
+		volatile Type volatileType;
+
+		[ExpectedWarning ("IL2074", nameof (GetTypeWithPublicConstructors), nameof (volatileType))]
+		private void WriteModReqType ()
+		{
+			var type = GetTypeWithPublicConstructors ();
+			volatileType = type;
+		}
+
 		private static void TestStringEmpty ()
 		{
 			RequirePublicMethods (string.Empty);
@@ -394,11 +407,31 @@ static void TestTypeGenericParameter ()
 				GenericField<Type>.field = GetUnknownType ();
 			}
 
+			[ExpectedWarning ("IL2097")]
+			[DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods)]
+			static volatile Type[] volatileTypeArray;
+
+			static void TestModReqTypeArray ()
+			{
+				volatileTypeArray = new Type[1];
+			}
+
+			[ExpectedWarning ("IL2097")]
+			[DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods)]
+			unsafe static delegate*<void> functionPointer;
+
+			unsafe static void TestFunctionPointer ()
+			{
+				functionPointer = null;
+			}
+
 			public static void Test ()
 			{
 				TestUnsupportedType ();
 				StringRef.Test ();
 				TestTypeGenericParameter ();
+				TestModReqTypeArray ();
+				TestFunctionPointer ();
 			}
 		}