Generate valid C# for forwarded specializations

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

src/Generator/AST/Utils.cs

@@ -151,7 +151,8 @@ namespace CppSharp.AST
             ClassTemplateSpecialization specialization, TemplateArgument a, ITypeMapDatabase typeMaps)
         {
             if (a.Type.Type == null ||
-                IsTypeExternal(specialization.TranslationUnit.Module, a.Type.Type))
+                IsTypeExternal(
+                    specialization.TemplatedDecl.TemplatedDecl.TranslationUnit.Module, a.Type.Type))
                 return true;
 
             var typeIgnoreChecker = new TypeIgnoreChecker(typeMaps);
@@ -178,7 +179,7 @@ namespace CppSharp.AST
         {
             if (type.TryGetDeclaration(out Declaration declaration))
             {
-                ClassTemplateSpecialization specialization = null;
+                ClassTemplateSpecialization specialization;
                 do
                 {
                     specialization = declaration as ClassTemplateSpecialization;

tests/NamespacesBase/NamespacesBase.h

@@ -80,8 +80,22 @@ class DLL_API TemplateWithIndependentFields
 {
 public:
     void useDependentPointer(const T* t);
+    const T& constField() const;
+private:
+    T* t = new T;
 };
 
+template <typename T>
+const T& TemplateWithIndependentFields<T>::constField() const
+{
+    return *t;
+}
+
+template <typename T>
+void TemplateWithIndependentFields<T>::useDependentPointer(const T* t)
+{
+}
+
 class DLL_API HasVirtualInCore
 {
 public:

tests/NamespacesDerived/Independent.h

@@ -0,0 +1,3 @@
+class Derived;
+template<typename T> class TemplateWithIndependentFields;
+typedef TemplateWithIndependentFields<Derived*> ForwardedInIndependentHeader;

tests/NamespacesDerived/NamespacesDerived.cpp

@@ -110,3 +110,7 @@ bool operator<<(const Base& b, const char* str)
 {
     return false;
 }
+
+void forceUseSpecializations(ForwardedInIndependentHeader value)
+{
+}

tests/NamespacesDerived/NamespacesDerived.h

@@ -1,5 +1,6 @@
 #include "../Tests.h"
 #include "../NamespacesBase/NamespacesBase.h"
+#include "Independent.h"
 
 // Namespace clashes with NamespacesBase.OverlappingNamespace
 // Test whether qualified names turn out right.
@@ -168,3 +169,5 @@ public:
      */
     class LinphoneAddress {};
 };
+
+DLL_API void forceUseSpecializations(ForwardedInIndependentHeader value);