fixed the MPI_Translate_ranks issues reported earlier, where a rank of

MPI_PROC_NULL translates to MPI_PROC_NULL, and an MPI_GROUP_EMPTY as one of
the groups doesn't cause a segmentation fault, but returns MPI_UNDEFINED for
all ranks to be translated.

This commit was SVN r12233.

ompi/group/group.c

@@ -43,20 +43,32 @@ int ompi_group_translate_ranks ( ompi_group_t *group1,
     int rank, proc, proc2;
     struct ompi_proc_t *proc1_pointer, *proc2_pointer;
     
+
+    if ( group1 == MPI_GROUP_EMPTY || group2 == MPI_GROUP_EMPTY) {
+	for (proc = 0; proc < n_ranks ; proc++) {
+	    ranks2[proc] = MPI_UNDEFINED;
+	}
+	return MPI_SUCCESS;
+    }
     /* loop over all ranks */
     for (proc = 0; proc < n_ranks; proc++) {
         rank=ranks1[proc];
-        proc1_pointer=group1->grp_proc_pointers[rank];
-        /* initialize to no "match" */
-        ranks2[proc] = MPI_UNDEFINED;
-        for (proc2 = 0; proc2 < group2->grp_proc_count; proc2++) 
-        {
-            proc2_pointer=group2->grp_proc_pointers[proc2];
-            if ( proc1_pointer == proc2_pointer) {
-                ranks2[proc] = proc2;
-                break;
-            }
-        }  /* end proc2 loop */
+	if (rank == MPI_PROC_NULL) {
+	    ranks2[proc] = MPI_PROC_NULL;
+	}
+	else {
+	    proc1_pointer=group1->grp_proc_pointers[rank];
+	    /* initialize to no "match" */
+	    ranks2[proc] = MPI_UNDEFINED;
+	    for (proc2 = 0; proc2 < group2->grp_proc_count; proc2++) 
+	    {
+		proc2_pointer=group2->grp_proc_pointers[proc2];
+		if ( proc1_pointer == proc2_pointer) {
+		    ranks2[proc] = proc2;
+		    break;
+		}
+	    }  /* end proc2 loop */
+	}
     } /* end proc loop */
 
     return MPI_SUCCESS;