Fixed code generation of subscript operator for types with non-default parameter usage.

src/Generator/Generators/CSharp/CSharpTextTemplate.cs

@@ -1216,8 +1216,15 @@ namespace CppSharp.Generators.CSharp
 
         private string GetPropertyName(Property prop)
         {
-            return prop.Parameters.Count == 0 ? prop.Name
-                : string.Format("this[{0}]", FormatMethodParameters(prop.Parameters));
+            var isIndexer = prop.Parameters.Count != 0;
+            var @params = prop.Parameters.Select(param => {
+                var p = new Parameter(param);
+                if (isIndexer)
+                    p.Usage = ParameterUsage.In;
+                return p;
+            });
+            return !isIndexer ? prop.Name
+                : string.Format("this[{0}]", FormatMethodParameters(@params));
         }
 
         private void GenerateVariable(Class @class, Type type, Variable variable)

tests/Common/Common.h

@@ -556,6 +556,9 @@ public:
     foo_t operator[](TestProperties b);
     Bar& operator[](unsigned long i);
     Bar& operator[](const TypeMappedIndex& key);
+    // Test that we do not generate 'ref int' parameters as C# does not allow it
+    int operator[](CS_OUT char key);
+
 private:
     foo_t p;
     TestProperties f;
@@ -578,6 +581,11 @@ Bar& TestIndexedProperties::operator[](const TypeMappedIndex& key)
 {
     return bar;
 }
+int TestIndexedProperties::operator[](CS_OUT char key)
+{
+    return key;
+}
+
 
 struct DLL_API TestIndexedPropertiesInValueType
 {