Generate an UnsupportedItem for typedefs.

PiperOrigin-RevId: 419748203
diff --git a/rs_bindings_from_cc/ast_visitor.cc b/rs_bindings_from_cc/ast_visitor.cc
index 13c5220..2824f86 100644
--- a/rs_bindings_from_cc/ast_visitor.cc
+++ b/rs_bindings_from_cc/ast_visitor.cc
@@ -358,6 +358,14 @@
   return true;
 }
 
+bool AstVisitor::VisitTypedefNameDecl(
+    clang::TypedefNameDecl* typedef_name_decl) {
+  PushUnsupportedItem(typedef_name_decl,
+                      "Typedef-name declarations are not supported yet",
+                      typedef_name_decl->getBeginLoc());
+  return true;
+}
+
 std::optional<std::string> AstVisitor::GetComment(
     const clang::Decl* decl) const {
   // This does currently not distinguish between different types of comments.