[CMake] Don't test for recent enough MPI version

We require MPI 2.1 anyway and nobody has reported problems.

cmake/modules/DuneMPI.cmake

@@ -42,37 +42,6 @@ if(MPI_C_FOUND)
   dune_register_package_flags(COMPILE_DEFINITIONS "ENABLE_MPI=1;MPICH_SKIP_MPICXX;MPIPP_H"
                               INCLUDE_DIRS "${MPI_DUNE_INCLUDE_PATH}"
                               LIBRARIES "${MPI_DUNE_LIBRARIES}")
-
-  # Check whether the MPI-2 standard is supported
-  include(CMakePushCheckState)
-  include(CheckFunctionExists)
-  include(CheckCXXSourceCompiles)
-  cmake_push_check_state()
-  set(CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES};${MPI_DUNE_LIBRARIES})
-  set(CMAKE_REQUIRED_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS} "-DENABLE_MPI=1 -DMPICH_SKIP_MPICXX -DMPIPP_H")
-  set(CMAKE_REQUIRED_INCLUDES ${CMAKE_REQUIRED_INCLUDES};${MPI_DUNE_INCLUDE_PATH})
-  check_function_exists(MPI_Finalized MPI_2)
-
-  # proper version check
-  check_cxx_source_compiles("
-    #include <mpi.h>
-
-    #if !((MPI_VERSION > 2) || (MPI_VERSION == 2 && MPI_SUBVERSION >= 1))
-    fail with a horribe compilation error due to old MPI version
-    #endif
-
-    int main(int argc, char** argv)
-    {
-      MPI_Init(&argc,&argv);
-      MPI_Finalize();
-    }
-" MPI_VERSION_SUPPORTED)
-
-  cmake_pop_check_state()
-
-  if(NOT MPI_VERSION_SUPPORTED)
-    message(FATAL_ERROR "Your MPI implementation is too old. Please upgrade to an MPI-2.1 compliant version.")
-  endif()
 endif(MPI_C_FOUND)
 
 # adds MPI flags to the targets

config.h.cmake

@@ -38,9 +38,7 @@
 /* Define to 1 if you have the <malloc.h> header file. */
 // Not used! #cmakedefine01 HAVE_MALLOC_H
 
-/* Define if you have the MPI library. This is only true if MPI was found by
-   configure _and_ if the application uses the DUNEMPICPPFLAGS (or the
-   deprecated MPI_CPPFLAGS) */
+/* Define if you have the MPI library.  */
 #cmakedefine HAVE_MPI ENABLE_MPI
 
 /* Define if you have the GNU GMP library. The value should be ENABLE_GMP
@@ -56,9 +54,6 @@
 /* Define to 1 if you have <sys/mman.h>. */
 #cmakedefine HAVE_SYS_MMAN_H 1
 
-/* Define to 1 if the MPI2 Standard is supported */
-#cmakedefine MPI_2 1
-
 /* begin private */
 
 /* Name of package */
@@ -96,6 +91,7 @@
 #define HAVE_NOEXCEPT_SPECIFIER 1
 #define HAVE_STD_DECLVAL 1
 #define HAVE_KEYWORD_FINAL 1
+#define MPI_2 1
 
 /* Define to 1 if the compiler properly supports testing for operator[] */
 #cmakedefine HAVE_IS_INDEXABLE_SUPPORT 1