Cleanup cmake MPI module

Move deactivation of cxx bindings to config.h

deactivate cxx bindings similar to FindMPI

cmake/modules/AddMPIFlags.cmake

+# The DUNE way to compile MPI applications is to use the CXX
+# compiler with MPI flags usually used for C. CXX bindings
+# are deactivated to prevent ABI problems.
+#
+# .. cmake_function:: add_dune_mpi_flags
+#
+#    .. cmake_param:: targets
+#       :single:
+#       :required:
+#       :positional:
+#
+#       The target list to add the MPI flags to.
+#
+include_guard(GLOBAL)
+
+# text for feature summary
+set_package_properties("MPI" PROPERTIES
+  DESCRIPTION "Message Passing Interface library"
+  PURPOSE "Parallel programming on multiple processors")
+
+if(MPI_C_FOUND)
+  set(HAVE_MPI ${MPI_C_FOUND})
+
+  dune_register_package_flags(COMPILE_DEFINITIONS "ENABLE_MPI=1"
+                              LIBRARIES MPI::MPI_C)
+endif()
+
+# adds MPI flags to the targets
+function(add_dune_mpi_flags)
+  cmake_parse_arguments(ADD_MPI "SOURCE_ONLY;OBJECT" "" "" ${ARGN}) # ignored
+  set(targets ${ADD_MPI_UNPARSED_ARGUMENTS})
+
+  if(MPI_C_FOUND)
+    foreach(target ${targets})
+      target_link_libraries(${target} PUBLIC MPI::MPI_C)
+      target_compile_definitions(${target} PUBLIC "ENABLE_MPI=1")
+    endforeach(target)
+  endif()
+endfunction(add_dune_mpi_flags)

cmake/modules/CMakeLists.txt

@@ -5,6 +5,7 @@ install(FILES
   AddBLASLapackFlags.cmake
   AddGMPFlags.cmake
   AddMETISFlags.cmake
+  AddMPIFlags.cmake
   AddParMETISFlags.cmake
   AddPTScotchFlags.cmake
   AddQuadMathFlags.cmake

cmake/modules/DuneCommonMacros.cmake

@@ -21,6 +21,10 @@ include(UseInkscape)
 find_package(Threads)
 include(AddThreadsFlags)
 
+# find the MPI library
+find_package(MPI 3.0 COMPONENTS C)
+include(AddMPIFlags)
+
 # find library for Threading Building Blocks
 find_package(TBB)
 include(AddTBBFlags)

cmake/modules/DuneMPI.cmake

-# Searches for MPI and thread support and sets the following
-# DUNE specific flags:
-#
-# MPI_DUNE_COMPILE_FLAGS Compiler flags for MPI applications.
-# MPI_DUNE_INCLUDE_PATH Include path for MPI applications.
-# MPI_DUNE_LINK_FLAGS Linker flags for MPI applications.
-# MPI_DUNE_LIBRARIES Libraries for MPI applications.
-#
-# The DUNE way to compile MPI applications is to use the CXX
-# compiler with MPI flags usually used for C. CXX bindings
-# are deactivated to prevent ABI problems.
-#
-# .. cmake_function:: add_dune_mpi_flags
-#
-#    .. cmake_param:: targets
-#       :single:
-#       :required:
-#       :positional:
-#
-#       The target list to add the MPI flags to.
-#
-include_guard(GLOBAL)
-
-find_package(MPI 3.0 COMPONENTS C)
-
-# text for feature summary
-set_package_properties("MPI" PROPERTIES
-  DESCRIPTION "Message Passing Interface library"
-  PURPOSE "Parallel programming on multiple processors")
-
-if(MPI_C_FOUND)
-  set(HAVE_MPI ${MPI_C_FOUND})
-  # We do not support the CXX bindings of MPI
-  set(MPI_DUNE_COMPILE_FLAGS ${MPI_C_COMPILE_FLAGS} CACHE STRING
-    "Compile flags used by DUNE when compiling MPI programs")
-  set(MPI_DUNE_INCLUDE_PATH ${MPI_C_INCLUDE_PATH} CACHE STRING
-    "Include path used by DUNE when compiling MPI programs")
-  # There seems to be no target specific include path, use the global one.
-  include_directories(${MPI_DUNE_INCLUDE_PATH})
-  set(MPI_DUNE_LINK_FLAGS ${MPI_C_LINK_FLAGS} CACHE STRING
-    "Linker flags used by DUNE when compiling MPI programs")
-  set(MPI_DUNE_LIBRARIES ${CMAKE_THREAD_LIBS_INIT} ${MPI_C_LIBRARIES} CACHE STRING
-    "Libraries used by DUNE when linking MPI programs")
-
-  # TODO check on where to position this exactly, doesn't look completely thought through
-  dune_register_package_flags(COMPILE_DEFINITIONS "ENABLE_MPI=1;MPICH_SKIP_MPICXX;OMPI_SKIP_MPICXX;MPIPP_H;MPI_NO_CPPBIND"
-                              INCLUDE_DIRS "${MPI_DUNE_INCLUDE_PATH}"
-                              LIBRARIES "${MPI_DUNE_LIBRARIES}")
-endif(MPI_C_FOUND)
-
-# adds MPI flags to the targets
-function(add_dune_mpi_flags)
-  cmake_parse_arguments(ADD_MPI "SOURCE_ONLY;OBJECT" "" "" ${ARGN})
-  if(ADD_MPI_SOURCE_ONLY)
-    set(_prefix SOURCE)
-  else()
-    set(_prefix TARGET)
-  endif()
-  if(MPI_C_FOUND)
-    separate_arguments(MPI_DUNE_COMPILE_FLAGS_LIST UNIX_COMMAND ${MPI_DUNE_COMPILE_FLAGS})
-    set_property(${_prefix} ${ADD_MPI_UNPARSED_ARGUMENTS} APPEND PROPERTY COMPILE_OPTIONS ${MPI_DUNE_COMPILE_FLAGS_LIST})
-    set_property(${_prefix} ${ADD_MPI_UNPARSED_ARGUMENTS} APPEND PROPERTY COMPILE_DEFINITIONS ENABLE_MPI=1
-      MPICH_SKIP_MPICXX OMPI_SKIP_MPICXX MPIPP_H)
-    if(NOT (ADD_MPI_SOURCE_ONLY OR ADD_MPI_OBJECT))
-    set_property(${_prefix} ${ADD_MPI_UNPARSED_ARGUMENTS} APPEND_STRING PROPERTY LINK_FLAGS " ${MPI_DUNE_LINK_FLAGS} ")
-    foreach(target ${ADD_MPI_UNPARSED_ARGUMENTS})
-      target_link_libraries(${target} PUBLIC ${MPI_DUNE_LIBRARIES})
-    endforeach(target ${ADD_MPI_UNPARSED_ARGUMENTS})
-    endif(NOT (ADD_MPI_SOURCE_ONLY OR ADD_MPI_OBJECT))
-  endif(MPI_C_FOUND)
-endfunction(add_dune_mpi_flags)
+message(DEPRECATION "The cmake file 'DuneMPI.cmake' is deprecated. Include 'AddMPIFlags.cmake' instead.")
+include(AddMPIFlags)

cmake/modules/DuneMacros.cmake

@@ -692,10 +692,6 @@ macro(dune_project)
   include_directories("${CMAKE_CURRENT_SOURCE_DIR}")
   add_definitions(-DHAVE_CONFIG_H)
 
-  # Search for MPI and set the relevant variables.
-  include(DuneMPI)
-
-
   # Create custom target for building the documentation
   # and provide macros for installing the docs and force
   # building them before.

config.h.cmake

@@ -47,6 +47,15 @@
 /* Define if you have the MPI library.  */
 #cmakedefine HAVE_MPI ENABLE_MPI
 
+/* Deactivate cxx bindings for MPI */
+#if HAVE_MPI
+#define MPICH_SKIP_MPICXX 1
+#define OMPI_SKIP_MPICXX 1
+#define MPI_NO_CPPBIND 1
+#define MPIPP_H
+#define _MPICC_H
+#endif
+
 /* Define if you have the GNU GMP library. The value should be ENABLE_GMP
    to facilitate activating and deactivating GMP using compile flags. */
 #cmakedefine HAVE_GMP ENABLE_GMP