Assert pipeline is active

Author: bernhardmgruber

libcudacxx/include/cuda/pipeline

@@ -135,6 +135,11 @@ public:
     return __released;
   }
 
+  _CCCL_API inline bool __is_active() const
+  {
+    return __active;
+  }
+
   _CCCL_API inline void producer_acquire()
   {
     barrier<_Scope>& __stage_barrier = __shared_state_get_stage(__head)->__consumed;
@@ -487,6 +492,11 @@ template <typename _Group, class _Tp, typename _Size, thread_scope _Scope>
 _CCCL_API inline async_contract_fulfillment __memcpy_async_pipeline(
   _Group const& __group, _Tp* __destination, _Tp const* __source, _Size __size, pipeline<_Scope>& __pipeline)
 {
+  if constexpr (_Scope != thread_scope_thread)
+  {
+    _CCCL_ASSERT(__pipeline.__is_active(), "The pipeline used for memcpy_async must be active (not quitted)");
+  }
+
   // 1. Set the completion mechanisms that can be used.
   //
   //    Do not (yet) allow async_bulk_group completion. Do not allow