avoid a warning

diff --git a/tests/performance/timing_step_22.cc b/tests/performance/timing_step_22.cc
index 0718aba3b9608937a6d05bde5c07bdd872ef60aa..c8b8a20b2424faa55c24ec59aa4b851005358022 100644 (file)
--- a/tests/performance/timing_step_22.cc
+++ b/tests/performance/timing_step_22.cc
@@ -528,7 +528,8 @@ StokesProblem<dim>::solve()
 
 template <int dim>
 void
-StokesProblem<dim>::output_results(const unsigned int refinement_cycle) const
+StokesProblem<dim>::output_results(
+  const unsigned int /*refinement_cycle*/) const
 {
   std::vector<std::string> solution_names(dim, "velocity");
   solution_names.emplace_back("pressure");