Fix an unused variable warning.

AFAICT this was fixed in GCC at some point.

diff --git a/source/grid/tria_accessor.cc b/source/grid/tria_accessor.cc
index 4c084ea65f0da58439e7153d21eee829747f3d51..b9a9c0cfd524ca06626be6eee9ad682a3d509221 100644 (file)
--- a/source/grid/tria_accessor.cc
+++ b/source/grid/tria_accessor.cc
@@ -2245,6 +2245,10 @@ void
 CellAccessor<dim, spacedim>::set_direction_flag(
   const bool new_direction_flag) const
 {
+  // Some older compilers (GCC 9) print an unused variable warning about
+  // new_direction_flag when it is only used in a subset of 'if constexpr'
+  // statements
+  (void)new_direction_flag;
   Assert(this->used(), TriaAccessorExceptions::ExcCellNotUsed());
   if constexpr (dim == spacedim)
     Assert(new_direction_flag == true,