From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Tue, 30 Nov 2021 18:42:30 +0000 (-0700)
Subject: Guard a forward declaration.
X-Git-Tag: v9.4.0-rc1~782^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F13015%2Fhead;p=dealii.git

Guard a forward declaration.
---

diff --git a/include/deal.II/base/multithread_info.h b/include/deal.II/base/multithread_info.h
index 34a74d0892..c0370ac57b 100644
--- a/include/deal.II/base/multithread_info.h
+++ b/include/deal.II/base/multithread_info.h
@@ -25,11 +25,14 @@
 
 #  include <memory>
 
+#  ifdef DEAL_II_WITH_TASKFLOW
 // forward declaration from <taskflow/taskflow.hpp>
 namespace tf
 {
   class Executor;
 }
+#  endif
+
 
 DEAL_II_NAMESPACE_OPEN