Access to template parameters via libclang

I'm having some trouble trying to access template parameter types using
libclang. Given the source:

template <typename T>
class List {
public:
    T at(int i);
};

class Client {
public:
    List<Client> childList();
    List<int> intList();
};

Navigating the AST with libclang gives the following tree, with each node
annotated with spelling, kind, type and result type:

<TU>
  List:ClassTemplate:Invalid:Invalid
    T:TemplateTypeParameter:TemplateTypeParm:Invalid
    <empty>:CXXAccessSpecifier:Invalid:Invalid
    at:CXXMethod:FunctionProto:TemplateTypeParm
      T:TypeRef:TemplateTypeParm:Invalid
      i:ParmDecl:Int:Invalid
  Client:ClassDecl:Record:Invalid
    <empty>:CXXAccessSpecifier:Invalid:Invalid
    childList:CXXMethod:FunctionProto:TemplateSpecialization
      List:TemplateRef:Invalid:Invalid
      class Client:TypeRef:Record:Invalid
    intList:CXXMethod:FunctionProto:TemplateSpecialization
      List:TemplateRef:Invalid:Invalid
    count:CXXMethod:FunctionProto:Int

Note that the subtree for the childList method helpfully has a TypeRef child
which tells us the return type is List<Client>, but the subtree for intList,
while it tells us that the return type is List<>, has no TypeRef node to
indicate exactly how List is specialized. What is the way to get the
specialization type when it is not a class?

Regards,

Vinay Sajip