From 682b1e7011c8cd75f988e85eb9be878539f24216 Mon Sep 17 00:00:00 2001
From: John Wellbelove <john.wellbelove@etlcpp.co.uk>
Date: Sun, 25 Jan 2026 11:09:59 +0100
Subject: [PATCH] Added type_list definitions for nth_type and observer

---
 include/etl/nth_type.h | 8 +++++---
 include/etl/observer.h | 6 ++++++
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/include/etl/nth_type.h b/include/etl/nth_type.h
index a38a25f5..82e58ef4 100644
--- a/include/etl/nth_type.h
+++ b/include/etl/nth_type.h
@@ -58,14 +58,16 @@ namespace etl
   {
     ETL_STATIC_ASSERT(Index < sizeof...(TTypes), "etl::nth_type index 'Index' out of bounds");
 
-    using type = typename private_nth_type::nth_type_helper<Index, TTypes...>::type;
+    using type      = typename private_nth_type::nth_type_helper<Index, TTypes...>::type;
+    using type_list = etl::type_list<TTypes...>;
   };
 
   //***********************************
   template <size_t Index, typename... TTypes>
-  struct nth_type<Index, etl::type_list<TTypes...>> : public nth_type<Index, TTypes...>
+  struct nth_type<Index, etl::type_list<TTypes...>>
   {
-    using typename nth_type<Index, TTypes...>::type;
+    using type      = typename nth_type<Index, TTypes...>::type;
+    using type_list = typename nth_type<Index, TTypes...>::type_list;
   };
 
   //***********************************
diff --git a/include/etl/observer.h b/include/etl/observer.h
index 133f8392..d722262b 100644
--- a/include/etl/observer.h
+++ b/include/etl/observer.h
@@ -309,6 +309,7 @@ namespace etl
 
     using observer<T1>::notification;
     using observer<TRest...>::notification;
+    using type_list = etl::type_list<T1, TRest...>;
   };
 
   //*****************************************************************
@@ -323,6 +324,8 @@ namespace etl
     virtual ~observer() = default;
 
     virtual void notification(T1) = 0;
+
+    using type_list = etl::type_list<T1>;
   };
 
   //*****************************************************************
@@ -337,6 +340,8 @@ namespace etl
     virtual ~observer() = default;
 
     virtual void notification() = 0;
+
+    using type_list = etl::type_list<>;
   };
 
   //*****************************************************************
@@ -350,6 +355,7 @@ namespace etl
   public:
 
     using observer<TTypes...>::notification;
+    using type_list = etl::type_list<TTypes...>;
   };
 
 #else