From 22e59435e5a9ec2e2a509cc46452480ae8e94d1e Mon Sep 17 00:00:00 2001
From: David Wells <drwells@email.unc.edu>
Date: Thu, 21 Dec 2023 09:46:17 -0500
Subject: [PATCH] Fix an unused variable warning.

AFAICT this was fixed in GCC at some point.
---
 source/grid/tria_accessor.cc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/source/grid/tria_accessor.cc b/source/grid/tria_accessor.cc
index 4c084ea65f..b9a9c0cfd5 100644
--- 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,
-- 
2.39.5