Fix TypeUtils for modopt types.

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -1377,10 +1377,12 @@ namespace ICSharpCode.Decompiler.CSharp
 						// cast to corresponding pointer type:
 						var pointerType = new PointerType(((ByReferenceType)inputType).ElementType);
 						return arg.ConvertTo(pointerType, this).WithILInstruction(inst);
-					} else {
+					} else if (arg.Type.GetStackType().IsIntegerType()) {
 						// ConversionKind.StopGCTracking should only be used with managed references,
 						// but it's possible that we're supposed to stop tracking something we just started to track.
 						return arg;
+					} else {
+						goto default;
 					}
 				case ConversionKind.SignExtend:
 					// We just need to ensure the input type before the conversion is signed.

ICSharpCode.Decompiler/TypeSystem/TypeUtils.cs

@@ -40,6 +40,9 @@ namespace ICSharpCode.Decompiler.TypeSystem
 				case TypeKind.Enum:
 					type = type.GetEnumUnderlyingType();
 					break;
+				case TypeKind.ModOpt:
+				case TypeKind.ModReq:
+					return type.SkipModifiers().GetSize();
 			}
 
 			var typeDef = type.GetDefinition();
@@ -232,6 +235,9 @@ namespace ICSharpCode.Decompiler.TypeSystem
 					// Type parameters are always considered StackType.O, even
 					// though they might be instantiated with primitive types.
 					return StackType.O;
+				case TypeKind.ModOpt:
+				case TypeKind.ModReq:
+					return type.SkipModifiers().GetStackType();
 			}
 			ITypeDefinition typeDef = type.GetEnumUnderlyingType().GetDefinition();
 			if (typeDef == null)
@@ -269,6 +275,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		/// </summary>
 		public static IType GetEnumUnderlyingType(this IType type)
 		{
+			type = type.SkipModifiers();
 			return (type.Kind == TypeKind.Enum) ? type.GetDefinition().EnumUnderlyingType : type;
 		}
 
@@ -284,6 +291,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		/// </remarks>
 		public static Sign GetSign(this IType type)
 		{
+			type = type.SkipModifiers();
 			if (type.Kind == TypeKind.Pointer)
 				return Sign.Unsigned;
 			var typeDef = type.GetEnumUnderlyingType().GetDefinition();
@@ -353,6 +361,7 @@ namespace ICSharpCode.Decompiler.TypeSystem
 		/// </summary>
 		public static PrimitiveType ToPrimitiveType(this IType type)
 		{
+			type = type.SkipModifiers();
 			if (type.Kind == TypeKind.Unknown) return PrimitiveType.Unknown;
 			var def = type.GetEnumUnderlyingType().GetDefinition();
 			return def != null ? def.KnownTypeCode.ToPrimitiveType() : PrimitiveType.None;