When the convertor is initialized a starting position set to -1 indicate

that the internal stack should not be constructed.

This commit was SVN r5840.

src/datatype/dt_pack.c

@@ -797,6 +797,7 @@ int32_t ompi_convertor_init_for_send( ompi_convertor_t* pConv,
         return ompi_convertor_create_stack_with_pos_contig( pConv, starting_pos, ompi_ddt_local_sizes );
     }
     pConv->fAdvance = ompi_convertor_pack_no_conversion;
+    if( -1 == starting_pos ) return OMPI_SUCCESS;
     if( starting_pos != 0 ) {
         return ompi_convertor_create_stack_with_pos_general( pConv, starting_pos, ompi_ddt_local_sizes );
     }

src/datatype/dt_unpack.c

@@ -654,6 +654,7 @@ int32_t ompi_convertor_init_for_recv( ompi_convertor_t* pConv, uint32_t flags,
         pConv->flags |= DT_FLAG_CONTIGUOUS;
         pConv->fAdvance = ompi_convertor_unpack_homogeneous_contig;
     }
+    if( -1 == starting_point ) return OMPI_SUCCESS;
     if( starting_point != 0 )
         return ompi_convertor_create_stack_with_pos_general( pConv, starting_point, ompi_ddt_local_sizes );
     return ompi_convertor_create_stack_at_begining( pConv, ompi_ddt_local_sizes );