From f8035898f91c56cf36e30c918f6005d5ff3e1f1d Mon Sep 17 00:00:00 2001
From: Bruno Turcksin <bruno.turcksin@gmail.com>
Date: Tue, 15 Feb 2022 19:03:48 +0000
Subject: [PATCH] Detect if ArborX was compiled with MPI support

---
 cmake/modules/FindARBORX.cmake   | 30 ++++++++++++++++++++++++++++++
 include/deal.II/base/config.h.in |  3 +++
 2 files changed, 33 insertions(+)

diff --git a/cmake/modules/FindARBORX.cmake b/cmake/modules/FindARBORX.cmake
index e4b9b00280..e6b295f6e0 100644
--- a/cmake/modules/FindARBORX.cmake
+++ b/cmake/modules/FindARBORX.cmake
@@ -32,6 +32,36 @@ FIND_PACKAGE(ArborX
 
 IF(ArborX_FOUND)
   GET_PROPERTY(ARBORX_INSTALL_INCLUDE_DIR TARGET ArborX::ArborX PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
+
+  #
+  # Check whether ArborX was compiled with MPI support
+  #
+  MESSAGE(STATUS
+    "Checking whether the found ArborX has MPI support:"
+    )
+
+  #
+  # Look for ArborX_Config.hpp - we'll query it to determine MPI support:
+  #
+  DEAL_II_FIND_FILE(ARBORX_CONFIG_HPP ArborX_Config.hpp
+    HINTS ${ARBORX_INSTALL_INCLUDE_DIR}
+    NO_DEFAULT_PATH NO_CMAKE_ENVIRONMENT_PATH NO_CMAKE_PATH
+    NO_SYSTEM_ENVIRONMENT_PATH NO_CMAKE_SYSTEM_PATH NO_CMAKE_FIND_ROOT_PATH
+    )
+
+  IF(EXISTS ${ARBORX_CONFIG_HPP})
+    #
+    # Determine whether ArborX was configured with MPI:
+    #
+    FILE(STRINGS "${ARBORX_CONFIG_HPP}" ARBORX_MPI_STRING
+      REGEX "#define ARBORX_ENABLE_MPI")
+    IF("${ARBORX_MPI_STRING}" STREQUAL "")
+      MESSAGE(STATUS "ArborX has no MPI support")
+    ELSE()
+      SET(DEAL_II_ARBORX_WITH_MPI TRUE)
+      MESSAGE(STATUS "ArborX has MPI support")
+    ENDIF()
+  ENDIF()
 ENDIF()
 
 DEAL_II_PACKAGE_HANDLE(ARBORX
diff --git a/include/deal.II/base/config.h.in b/include/deal.II/base/config.h.in
index 89e2dc3552..11ac41cfb5 100644
--- a/include/deal.II/base/config.h.in
+++ b/include/deal.II/base/config.h.in
@@ -210,6 +210,9 @@
 #cmakedefine DEAL_II_ADOLC_WITH_ADVANCED_BRANCHING
 #cmakedefine DEAL_II_ADOLC_WITH_TAPELESS_REFCOUNTING
 
+/* cmake/modules/FindARBORX.cmake */
+#cmakedefine DEAL_II_ARBORX_WITH_MPI
+
 /* cmake/modules/FindARPACK.cmake */
 #cmakedefine DEAL_II_ARPACK_WITH_PARPACK
 
-- 
2.39.5