From 0dbbc4ba57b414933083b8d247063a8e7252c152 Mon Sep 17 00:00:00 2001
From: John Wellbelove <github@wellbelove.co.uk>
Date: Sun, 10 Nov 2024 10:10:10 +0000
Subject: [PATCH] Updated nth_type to handle a type list of zero length

---
 include/etl/nth_type.h | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/include/etl/nth_type.h b/include/etl/nth_type.h
index f870bb7c..5bc1e836 100644
--- a/include/etl/nth_type.h
+++ b/include/etl/nth_type.h
@@ -30,22 +30,49 @@ SOFTWARE.
 #define ETL_NTH_TYPE_INCLUDED
 
 #include "platform.h"
+#include "static_assert.h"
 
 namespace etl
 {
 #if ETL_USING_CPP11
+
+  //***************************************************************************
+  /// Finds the nth type in a variadic type parameter.
+  //***************************************************************************
+  template <size_t N, typename... TTypes>
+  struct nth_type;
+
+  //***************************************************************************
+  /// Finds the nth type in a variadic type parameter.
+  //***************************************************************************
   template <size_t N, typename T1, typename... TRest>
-  struct nth_type
+  struct nth_type<N, T1, TRest...>
   {
+    ETL_STATIC_ASSERT(N <= sizeof...(TRest), "etl::nth_type out of range for type list");
+
     using type = typename nth_type<N - 1U, TRest...>::type;
   };
 
+  //***************************************************************************
+  /// Finds the 0thth type in a variadic type parameter.
+  //***************************************************************************
   template <typename T1, typename... TRest>
   struct nth_type<0U, T1, TRest...>
   {
     using type = T1;
   };
 
+  //***************************************************************************
+  /// Finds the 0thth type in a variadic type parameter.
+  //***************************************************************************
+  template <size_t N>
+  struct nth_type<N>
+  {
+  };
+
+  //***************************************************************************
+  /// Finds the nth type in a variadic type parameter.
+  //***************************************************************************
   template <size_t N, typename... TTypes>
   using nth_type_t = typename nth_type<N, TTypes...>::type;
 #endif