[Release][MPI] Add check for MPI standard version and warn if installed version is < 2.1

As decided in the doodle for FS#1395, really old MPI versions will be
deprecated in the 2.3 release.

This patch adds an additional check to the MPI tests for autotools and
cmake that makes sure the user has an MPI which is at least compliant
with MPI-2.1. If the user's version is older, a warning is generated.

The test uses version macros instead of the more standard runtime
MPI version query interface to avoid problems when cross-compiling.

cmake/modules/DuneMPI.cmake

@@ -42,12 +42,34 @@ if(MPI_CXX_FOUND)
   # 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()
+
+  # TODO: Turn into an error after 2.3 release
+  if(NOT MPI_VERSION_SUPPORTED)
+    MESSAGE(WARNING "Support for your MPI implementation is DEPRECATED and will be removed after the next release. Please upgrade to an MPI-2.1 compliant version.")
+  endif()
 endif(MPI_CXX_FOUND)
 
 # adds MPI flags to the targets

m4/dune_mpi.m4

@@ -157,6 +157,28 @@ AC_DEFUN([DUNE_MPI],[
           with_mpi=no]
     )
 
+    AC_MSG_CHECKING([whether MPI is recent enough (MPI-2.1)])
+    # check MPI version and issue a deprecation warning if MPI is older than 2.1
+    # TODO: Replace with error after 2.3 release
+    AC_LANG_PUSH([C++])
+    AC_COMPILE_IFELSE(
+      [AC_LANG_SOURCE(
+        [ #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(); }])],
+        [ AC_MSG_RESULT([yes]) ],
+        [ AC_MSG_RESULT([no])
+          AC_MSG_WARN([You are using a very old version of MPI that
+          is not compatible with the MPI-2.1 standard. Support for your
+          version of MPI is deprecated and will be removed after the next
+          release!])
+          mpi_deprecated=yes]
+    )
+
     AS_IF([test "x$mpiruntest" != "xyes"],[
       AC_MSG_WARN([Disabled test whether running with $dune_MPI_VERSION works.])
     ],[
@@ -210,7 +232,11 @@ AC_DEFUN([DUNE_MPI],[
 
   AM_CONDITIONAL(MPI, [test "x$with_mpi" != "xno"])
 
-  DUNE_ADD_SUMMARY_ENTRY([MPI],[$with_mpi])
+  AS_IF([test "x$mpi_deprecated" == "xyes"],[
+    DUNE_ADD_SUMMARY_ENTRY([MPI],[$with_mpi (deprecated MPI version)])
+    ],[
+    DUNE_ADD_SUMMARY_ENTRY([MPI],[$with_mpi])
+    ])
 
   AC_LANG_POP
 ])