From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Thu, 20 Jan 2022 17:45:50 +0000 (-0700)
Subject: Define MPI_COMM_NULL when not using MPI.
X-Git-Tag: v9.4.0-rc1~583^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cfc5c8fa1c4a701045a0b5eb5932b8a2c9ed3874;p=dealii.git

Define MPI_COMM_NULL when not using MPI.
---

diff --git a/include/deal.II/base/mpi.h b/include/deal.II/base/mpi.h
index 4317703957..68e2a96187 100644
--- a/include/deal.II/base/mpi.h
+++ b/include/deal.II/base/mpi.h
@@ -44,6 +44,9 @@ using MPI_Op       = int;
 #  ifndef MPI_COMM_SELF
 #    define MPI_COMM_SELF 0
 #  endif
+#  ifndef MPI_COMM_NULL
+#    define MPI_COMM_NULL 0
+#  endif
 #  ifndef MPI_REQUEST_NULL
 #    define MPI_REQUEST_NULL 0
 #  endif