Generate valid C++ for protected destructors

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

src/Generator/Passes/SymbolsCodeGenerator.cs

@@ -201,21 +201,24 @@ namespace CppSharp.Passes
             bool needSubclass = method.Access == AccessSpecifier.Protected ||
                 ((Class) method.Namespace).IsAbstract;
             string @namespace = method.Namespace.Visit(cppTypePrinter);
-            Write("extern \"C\" ");
+            if (!needSubclass)
+                Write("extern \"C\" ");
             Write($"{GetExporting()}void {wrapper}");
             if (needSubclass)
                 Write("Protected");
 
             string instance = Helpers.InstanceField;
-            string @class = needSubclass ? wrapper : @namespace;
-            Write($"({@class}* {instance}) {{ {instance}->~{method.Namespace.Name}(); }};");
             if (needSubclass)
             {
-                NewLine();
-                Write($@"extern ""C"" {GetExporting()}void {wrapper}({wrapper}* {instance}) {{ {
-                    instance}->{wrapper}Protected({instance}); }}");
+                string @class = wrapper + method.Namespace.Name;
+                WriteLine($"() {{ this->~{@class}(); }} }};");
+                Write($@"extern ""C"" {GetExporting()}void {wrapper}({
+                    @class}* {instance}) {{ {instance}->{wrapper}Protected");
             }
-            NewLine();
+            else
+                Write($@"({$"{@namespace}*{instance}"}) {{ {
+                    instance}->~{method.Namespace.Name}");
+            WriteLine("(); }");
         }
 
         private void TakeFunctionAddress(Function function, string wrapper)

tests/CSharp/CSharp.h

@@ -1502,6 +1502,12 @@ struct DLL_API ClassMicrosoftObjectAlignment : ClassMicrosoftObjectAlignmentBase
     bool boolean;
 };
 
+class DLL_API ProtectedDestructor
+{
+protected:
+    ~ProtectedDestructor() {}
+};
+
 DLL_API extern const unsigned ClassCustomTypeAlignmentOffsets[5];
 DLL_API extern const unsigned ClassCustomObjectAlignmentOffsets[2];
 DLL_API extern const unsigned ClassMicrosoftObjectAlignmentOffsets[4];