From b742607c769cbb666aa6f34208cb7a7054f8ef92 Mon Sep 17 00:00:00 2001
From: Scott Giese <scttgs0@gmail.com>
Date: Thu, 3 Oct 2019 11:50:07 -0500
Subject: [PATCH] [ReaderWriteSTG] fix for missing header.

---
 simgear/scene/tgdb/ReaderWriterSTG.hxx | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/simgear/scene/tgdb/ReaderWriterSTG.hxx b/simgear/scene/tgdb/ReaderWriterSTG.hxx
index 19a1e7ea..74b6c77b 100644
--- a/simgear/scene/tgdb/ReaderWriterSTG.hxx
+++ b/simgear/scene/tgdb/ReaderWriterSTG.hxx
@@ -22,6 +22,8 @@
 #ifndef _READERWRITERSTG_HXX
 #define _READERWRITERSTG_HXX
 
+#include <functional>
+
 #include <osgDB/ReaderWriter>
 #include <simgear/math/sg_types.hxx>