From fd00bd94b213f3c75af8cbfd9dde4ad0141fe6ee Mon Sep 17 00:00:00 2001
From: Patrick Shriwise <pshriwise@gmail.com>
Date: Fri, 12 Mar 2021 08:45:38 -0600
Subject: [PATCH] Relying on the libmesh communicator to create new mesh
 instances.

---
 include/openmc/mesh.h | 1 +
 src/initialize.cpp    | 2 ++
 src/mesh.cpp          | 7 ++++---
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/include/openmc/mesh.h b/include/openmc/mesh.h
index d787db15a..cc0169ce0 100644
--- a/include/openmc/mesh.h
+++ b/include/openmc/mesh.h
@@ -55,6 +55,7 @@ extern std::vector<std::unique_ptr<Mesh>> meshes;
 namespace settings {
 // used when creating new libMesh::Mesh instances
 extern std::unique_ptr<libMesh::LibMeshInit> libmesh_init;
+extern const libMesh::Parallel::Communicator* libmesh_comm;
 }
 #endif
 
diff --git a/src/initialize.cpp b/src/initialize.cpp
index c480392cb..f6e927b68 100644
--- a/src/initialize.cpp
+++ b/src/initialize.cpp
@@ -80,6 +80,8 @@ if (!settings::libmesh_init && !libMesh::initialized())
   // pass command line args, empty MPI communicator, and number of threads
   settings::libmesh_init = std::make_unique<libMesh::LibMeshInit>(argc, argv, 0, n_threads);
 #endif
+
+  settings::libmesh_comm = &(settings::libmesh_init->comm());
 }
 
 #endif
diff --git a/src/mesh.cpp b/src/mesh.cpp
index f74691334..30553c8c7 100644
--- a/src/mesh.cpp
+++ b/src/mesh.cpp
@@ -60,6 +60,7 @@ std::vector<std::unique_ptr<Mesh>> meshes;
 #ifdef LIBMESH
 namespace settings {
 std::unique_ptr<libMesh::LibMeshInit> libmesh_init;
+const libMesh::Parallel::Communicator* libmesh_comm;
 }
 #endif
 
@@ -2150,11 +2151,11 @@ LibMesh::LibMesh(const std::string& filename)
 
 void LibMesh::initialize()
 {
-  if (!settings::libmesh_init) {
-    fatal_error("Attempting to use an unstructured mesh without a libMesh::LibMeshInit object.");
+  if (!settings::libmesh_comm) {
+    fatal_error("Attempting to use an unstructured mesh without a libMesh communicator.");
   }
 
-  m_ = std::make_unique<libMesh::Mesh>(settings::libmesh_init->comm(), n_dimension_);
+  m_ = std::make_unique<libMesh::Mesh>(*settings::libmesh_comm, n_dimension_);
   m_->read(filename_);
   m_->prepare_for_use();