// Get predicates declared on the trait.
let predicates = tcx.super_predicates_of(data.def_id());
- let obligations = predicates.predicates.iter().map(|&(mut pred, span)| {
- // when parent predicate is non-const, elaborate it to non-const predicates.
- if data.constness == ty::BoundConstness::NotConst {
- pred = pred.without_const(tcx);
- }
-
- let cause = obligation.cause.clone().derived_cause(
- bound_predicate.rebind(data),
- |derived| {
- traits::ImplDerivedObligation(Box::new(
- traits::ImplDerivedObligationCause {
- derived,
- impl_def_id: data.def_id(),
- span,
- },
- ))
- },
- );
- predicate_obligation(
- pred.subst_supertrait(tcx, &bound_predicate.rebind(data.trait_ref)),
- obligation.param_env,
- cause,
- )
- });
+ let obligations =
+ predicates.predicates.iter().enumerate().map(|(index, &(mut pred, span))| {
+ // when parent predicate is non-const, elaborate it to non-const predicates.
+ if data.constness == ty::BoundConstness::NotConst {
+ pred = pred.without_const(tcx);
+ }
+
+ let cause = obligation.cause.clone().derived_cause(
+ bound_predicate.rebind(data),
+ |derived| {
+ traits::ImplDerivedObligation(Box::new(
+ traits::ImplDerivedObligationCause {
+ derived,
+ impl_def_id: data.def_id(),
+ impl_def_predicate_index: Some(index),
+ span,
+ },
+ ))
+ },
+ );
+ predicate_obligation(
+ pred.subst_supertrait(tcx, &bound_predicate.rebind(data.trait_ref)),
+ obligation.param_env,
+ cause,
+ )
+ });
debug!(?data, ?obligations, "super_predicates");
// Only keep those bounds that we haven't already seen.