Fixed the generated C# for templated indexers specialised with enums.

Signed-off-by: Dimitar Dobrev <dpldobrev@protonmail.com>

src/AST/TypeExtensions.cs

@@ -32,7 +32,7 @@
 
         public static bool IsEnumType(this Type t)
         {
-            var tag = t as TagType;
+            var tag = t.Desugar() as TagType;
             
             if (tag == null)
                 return false;

tests/CSharp/CSharpTemplates.h

@@ -523,6 +523,12 @@ DependentValueFields<OnlySpecialisedInTypeArg<T>> OnlySpecialisedInTypeArg<T>::r
 {
 }
 
+enum class UsedInTemplatedIndexer
+{
+    Item1,
+    Item2
+};
+
 // we optimise specialisations so that only actually used ones are wrapped
 void forceUseSpecializations(IndependentFields<int> _1, IndependentFields<bool> _2,
                              IndependentFields<T1> _3, IndependentFields<std::string> _4,
@@ -530,8 +536,9 @@ void forceUseSpecializations(IndependentFields<int> _1, IndependentFields<bool>
                              VirtualTemplate<int> _6, VirtualTemplate<bool> _7,
                              HasDefaultTemplateArgument<int, int> _8, DerivedChangesTypeName<T1> _9,
                              TemplateWithIndexer<int> _10, TemplateWithIndexer<T1> _11,
-                             TemplateWithIndexer<T2*> _12, TemplateDerivedFromRegularDynamic<RegularDynamic> _13,
-                             IndependentFields<OnlySpecialisedInTypeArg<double>> _14, std::string s);
+                             TemplateWithIndexer<T2*> _12, TemplateWithIndexer<UsedInTemplatedIndexer> _13,
+                             TemplateDerivedFromRegularDynamic<RegularDynamic> _14,
+                             IndependentFields<OnlySpecialisedInTypeArg<double>> _15, std::string s);
 
 void hasIgnoredParam(DependentValueFields<IndependentFields<Ignored>> ii);
 
@@ -551,6 +558,7 @@ template class DLL_API VirtualTemplate<bool>;
 template class DLL_API HasDefaultTemplateArgument<int, int>;
 template class DLL_API DerivedChangesTypeName<T1>;
 template class DLL_API TemplateWithIndexer<int>;
+template class DLL_API TemplateWithIndexer<UsedInTemplatedIndexer>;
 template class DLL_API TemplateWithIndexer<T1>;
 template class DLL_API TemplateWithIndexer<T2*>;
 template class DLL_API TemplateDerivedFromRegularDynamic<RegularDynamic>;