DWARF 3 introduced DW_AT_object_pointer, for marking the "this" parameter of a method. GCC does not emit this, so currently GDB has to use a heuristic to detect this.
-- Summary: GCC does not emit DW_AT_object_pointer Product: gcc Version: 4.6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: debug AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: tromey at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45110