Implement MPI::SEEK_{SET, END, POS} for the C++ bindings, working around

some issues with the C #defines SEEK_{SET, END, POS}.  The workaround
involves some hackery that should work in almost every common use case
for the C stdio constants (and all the legal issues of the MPI constants).
The one issue is that the C stdio constants are now const ints instead
of #defines, which means that #ifdef checks will fail for the constants.

Behavior can be disabled at either configure time or build time.

Refs trac:387

This commit was SVN r12121.

The following Trac tickets were found above:
  Ticket 387 --> https://svn.open-mpi.org/trac/ompi/ticket/387

config/ompi_configure_options.m4

@@ -259,6 +259,19 @@ else
     WANT_MPI_CXX_SUPPORT=0
 fi
 
+AC_MSG_CHECKING([if want MPI::SEEK_SET support])
+AC_ARG_ENABLE([mpi-cxx-seek],
+    [AC_HELP_STRING([--enable-mpi-cxx-seek],
+                   [enable support for MPI::SEEK_SET, MPI::SEEK_END, and MPI::SEEK_POS in C++ bindings (default: enabled)])])
+if test "$enable_mpi_cxx_seek" != "no" ; then
+  AC_MSG_RESULT([yes])
+  OMPI_WANT_MPI_CXX_SEEK=1
+else
+  AC_MSG_RESULT([no])
+  OMPI_WANT_MPI_CXX_SEEK=0
+fi
+AC_DEFINE_UNQUOTED([OMPI_WANT_MPI_CXX_SEEK], [$OMPI_WANT_MPI_CXX_SEEK],
+    [do we want to try to work around C++ bindings SEEK_* issue?])
 
 #
 # Do we want to disable weak symbols for some reason?

ompi/include/mpi.h.in

@@ -74,6 +74,9 @@
 /* Whether we want MPI cxx support or not */
 #undef OMPI_WANT_CXX_BINDINGS
 
+/* do we want to try to work around C++ bindings SEEK_* issue? */
+#undef OMPI_WANT_MPI_CXX_SEEK
+
 /* Whether a const_cast on a 2-d array will work with the C++ compiler */
 #undef OMPI_CXX_SUPPORTS_2D_CONST_CAST
 

ompi/mpi/cxx/constants.h

@@ -249,6 +249,12 @@ OMPI_DECLSPEC extern const int MODE_SEQUENTIAL;
 
 OMPI_DECLSPEC extern const int DISPLACEMENT_CURRENT;
 
+#if !defined(OMPI_IGNORE_CXX_SEEK) && OMPI_WANT_MPI_CXX_SEEK
+OMPI_DECLSPEC extern const int SEEK_SET;
+OMPI_DECLSPEC extern const int SEEK_CUR;
+OMPI_DECLSPEC extern const int SEEK_END;
+#endif
+
 OMPI_DECLSPEC extern const int MAX_DATAREP_STRING;
 
 // one-sided constants

ompi/mpi/cxx/mpicxx.cc

@@ -18,8 +18,20 @@
 
 //
 
+#include <stdio.h>
+static const int ompi_stdio_seek_set = SEEK_SET;
+static const int ompi_stdio_seek_cur = SEEK_CUR;
+static const int ompi_stdio_seek_end = SEEK_END;
+
 #include "mpicxx.h"
 
+#if OMPI_WANT_MPI_CXX_SEEK
+
+const int SEEK_SET = ompi_stdio_seek_set;
+const int SEEK_CUR = ompi_stdio_seek_cur;
+const int SEEK_END = ompi_stdio_seek_end;
+#endif
+
 namespace MPI {
 
 #if ! OMPI_HAVE_CXX_EXCEPTION_SUPPORT
@@ -259,6 +271,12 @@ const int MODE_SEQUENTIAL = MPI_MODE_SEQUENTIAL;
 
 const int DISPLACEMENT_CURRENT = MPI_DISPLACEMENT_CURRENT;
 
+#if OMPI_WANT_MPI_CXX_SEEK
+const int SEEK_SET = MPI_SEEK_SET;
+const int SEEK_CUR = MPI_SEEK_CUR;
+const int SEEK_END = MPI_SEEK_END;
+#endif
+
 const int MAX_DATAREP_STRING = MPI_MAX_DATAREP_STRING;
 
 // one-sided constants

ompi/mpi/cxx/mpicxx.h

@@ -36,6 +36,23 @@
 
 #include <stdarg.h>
 
+#if !defined(OMPI_IGNORE_CXX_SEEK) & OMPI_WANT_MPI_CXX_SEEK
+// include so that we can smash SEEK_* properly
+#include <stdio.h>
+
+// smash SEEK_* #defines
+#ifdef SEEK_SET
+#undef SEEK_SET
+#undef SEEK_CUR
+#undef SEEK_END
+#endif
+
+// make globally scoped constants to replace smashed #defines
+extern const int SEEK_SET;
+extern const int SEEK_CUR;
+extern const int SEEK_END;
+#endif
+
 // forward declare so that we can still do inlining
 struct opal_mutex_t;