Back out r19805 and replace it with something a bit better, based on a

suggestion from George during review.

Refs trac:1595.

This commit was SVN r19818.

The following SVN revision numbers were found above:
  r19805 --> open-mpi/ompi@bc710baa75

The following Trac tickets were found above:
  Ticket 1595 --> https://svn.open-mpi.org/trac/ompi/ticket/1595

config/ompi_configure_options.m4

@@ -345,25 +345,20 @@ mpi_param_check=ompi_mpi_param_check
 if test "$with_mpi_param_check" = "no" -o \
     "$with_mpi_param_check" = "never"; then
     mpi_param_check=0
-    mpi_param_check_level=0
     AC_MSG_RESULT([never])
 elif test "$with_mpi_param_check" = "yes" -o \
     "$with_mpi_param_check" = "always"; then
     mpi_param_check=1
-    mpi_param_check_level=1
     AC_MSG_RESULT([always])
 elif test "$with_mpi_param_check" = "runtime" -o \
     -z "$with_mpi_params_check"; then
     AC_MSG_RESULT([runtime])
-    mpi_param_check_level=2
 else
     AC_MSG_RESULT([unknown])
     AC_MSG_WARN([*** Unrecognized --with-mpi-param-check value])
     AC_MSG_WARN([*** See "configure --help" output])
     AC_MSG_WARN([*** Defaulting to "runtime"])
 fi
-AC_DEFINE_UNQUOTED(MPI_PARAM_CHECK_LEVEL, $mpi_param_check_level,
-    [Whether we want to check MPI parameters never (0), always (1), or decide at run-time (2) -- this macro mainly for displaying the right value in ompi_info])
 AC_DEFINE_UNQUOTED(MPI_PARAM_CHECK, $mpi_param_check,
     [Whether we want to check MPI parameters always, never, or decide at run-time])
 

ompi/tools/ompi_info/param.cc

@@ -501,8 +501,27 @@ void ompi_info::do_config(bool want_all)
   const string f90profiling((OMPI_ENABLE_MPI_PROFILING && OMPI_WANT_F90_BINDINGS) ?
                             "yes" : "no");
   const string cxxexceptions(OMPI_HAVE_CXX_EXCEPTION_SUPPORT ? "yes" : "no");
-  const string paramcheck(0 == MPI_PARAM_CHECK_LEVEL ? "never" :
-                          1 == MPI_PARAM_CHECK_LEVEL ? "always" : "runtime");
+  // Do a little preprocessor trickery here to figure out the
+  // tri-state of MPI_PARAM_CHECK (which will be either 0, 1, or
+  // ompi_mpi_param_check).  The preprocessor will only allow
+  // comparisons against constants, so you'll get a warning if you
+  // check MPI_PARAM_CHECK against 0 or 1, but its real value is the
+  // string ompi_mpi_param_check.  So define ompi_mpi_param_check to
+  // be a constant, and then all the preprocessor comparisons work out
+  // ok.  Note that we chose the preprocessor comparison route because
+  // it is not sufficient to simply set the variable
+  // ompi_mpi_param_check to a non-0/non-1 value.  This is because the
+  // compiler will generate a warning that that C variable is unused
+  // when MPI_PARAM_CHECK is hard-coded to 0 or 1.
+  string paramcheck;
+#define ompi_mpi_param_check 999
+#if 0 == MPI_PARAM_CHECK
+  paramcheck = "never";
+#elif 1 == MPI_PARAM_CHECK
+  paramcheck = "always";
+#else
+  paramcheck = "runtime";
+#endif
   string threads;
   const string want_libltdl(OMPI_WANT_LIBLTDL ? "yes" : "no");
   const string mpirun_prefix_by_default(ORTE_WANT_ORTERUN_PREFIX_BY_DEFAULT ?