if cx.tcx.is_diagnostic_item(sym::Result, def.did()) {
if let ty::Adt(adt, _) = substs.type_at(0).kind() {
if cx.tcx.is_diagnostic_item(sym::cstring_type, adt.did()) {
if cx.tcx.is_diagnostic_item(sym::Result, def.did()) {
if let ty::Adt(adt, _) = substs.type_at(0).kind() {
if cx.tcx.is_diagnostic_item(sym::cstring_type, adt.did()) {