Fixed the parsing of fields with a template template parameter type.

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

src/AST/TypeExtensions.cs

@@ -134,12 +134,20 @@
                         return decl != null;
                     }
 
-                    var templatedClass = ((ClassTemplate) type.Template).TemplatedClass;
+                    var classTemplate = type.Template as ClassTemplate;
+                    if (classTemplate != null)
+                    {
+                        var templatedClass = classTemplate.TemplatedClass;
                         decl = templatedClass.CompleteDeclaration == null
                             ? templatedClass as T
                             : (T) templatedClass.CompleteDeclaration;
                         return decl != null;
                     }
+
+                    var templateTemplateParameter = type.Template as TemplateTemplateParameter;
+                    if (templateTemplateParameter != null)
+                        return (decl = templateTemplateParameter.TemplatedDecl as T) != null;
+                }
                 tagType = (TagType) type.Desugared;
             }
             else

tests/Common/Common.h

@@ -1154,3 +1154,9 @@ struct _Aligned<_Len, char>
 };
 
 typedef _Aligned<16, char>::type type;
+
+template <typename T, template <typename> class InteriorRings = SpecialisesVoid>
+struct polygon
+{
+    InteriorRings<T> interior_rings;
+};