}
// NOTE: doesn't use `for_each_relevant_impl` to avoid looking at anything besides blanket impls
let trait_impls = cx.tcx.trait_impls_of(trait_def_id);
- for &impl_def_id in trait_impls.blanket_impls() {
+ 'blanket_impls: for &impl_def_id in trait_impls.blanket_impls() {
trace!(
"get_blanket_impls: Considering impl for trait '{:?}' {:?}",
trait_def_id,
impl_def_id
);
let trait_ref = cx.tcx.bound_impl_trait_ref(impl_def_id).unwrap();
- let is_param = matches!(trait_ref.0.self_ty().kind(), ty::Param(_));
- let may_apply = is_param && cx.tcx.infer_ctxt().enter(|infcx| {
- let substs = infcx.fresh_substs_for_item(DUMMY_SP, item_def_id);
- let ty = ty.subst(infcx.tcx, substs);
- let param_env = EarlyBinder(param_env).subst(infcx.tcx, substs);
+ if !matches!(trait_ref.0.self_ty().kind(), ty::Param(_)) {
+ continue;
+ }
+ let infcx = cx.tcx.infer_ctxt().build();
+ let substs = infcx.fresh_substs_for_item(DUMMY_SP, item_def_id);
+ let impl_ty = ty.subst(infcx.tcx, substs);
+ let param_env = EarlyBinder(param_env).subst(infcx.tcx, substs);
- let impl_substs = infcx.fresh_substs_for_item(DUMMY_SP, impl_def_id);
- let trait_ref = trait_ref.subst(infcx.tcx, impl_substs);
+ let impl_substs = infcx.fresh_substs_for_item(DUMMY_SP, impl_def_id);
+ let impl_trait_ref = trait_ref.subst(infcx.tcx, impl_substs);
- // Require the type the impl is implemented on to match
- // our type, and ignore the impl if there was a mismatch.
- let cause = traits::ObligationCause::dummy();
- let eq_result = infcx.at(&cause, param_env).eq(trait_ref.self_ty(), ty);
- if let Ok(InferOk { value: (), obligations }) = eq_result {
- // FIXME(eddyb) ignoring `obligations` might cause false positives.
- drop(obligations);
+ // Require the type the impl is implemented on to match
+ // our type, and ignore the impl if there was a mismatch.
+ let cause = traits::ObligationCause::dummy();
+ let Ok(eq_result) = infcx.at(&cause, param_env).eq(impl_trait_ref.self_ty(), impl_ty) else {
+ continue
+ };
+ let InferOk { value: (), obligations } = eq_result;
+ // FIXME(eddyb) ignoring `obligations` might cause false positives.
+ drop(obligations);
- trace!(
- "invoking predicate_may_hold: param_env={:?}, trait_ref={:?}, ty={:?}",
- param_env,
- trait_ref,
- ty
- );
- let predicates = cx
- .tcx
- .predicates_of(impl_def_id)
- .instantiate(cx.tcx, impl_substs)
- .predicates
- .into_iter()
- .chain(Some(
- ty::Binder::dummy(trait_ref)
- .to_poly_trait_predicate()
- .map_bound(ty::PredicateKind::Trait)
- .to_predicate(infcx.tcx),
- ));
- for predicate in predicates {
- debug!("testing predicate {:?}", predicate);
- let obligation = traits::Obligation::new(
- traits::ObligationCause::dummy(),
- param_env,
- predicate,
- );
- match infcx.evaluate_obligation(&obligation) {
- Ok(eval_result) if eval_result.may_apply() => {}
- Err(traits::OverflowError::Canonical) => {}
- Err(traits::OverflowError::ErrorReporting) => {}
- _ => {
- return false;
- }
- }
- }
- true
- } else {
- false
+ trace!(
+ "invoking predicate_may_hold: param_env={:?}, impl_trait_ref={:?}, impl_ty={:?}",
+ param_env,
+ impl_trait_ref,
+ impl_ty
+ );
+ let predicates = cx
+ .tcx
+ .predicates_of(impl_def_id)
+ .instantiate(cx.tcx, impl_substs)
+ .predicates
+ .into_iter()
+ .chain(Some(
+ ty::Binder::dummy(impl_trait_ref)
+ .to_poly_trait_predicate()
+ .map_bound(ty::PredicateKind::Trait)
+ .to_predicate(infcx.tcx),
+ ));
+ for predicate in predicates {
+ debug!("testing predicate {:?}", predicate);
+ let obligation = traits::Obligation::new(
+ traits::ObligationCause::dummy(),
+ param_env,
+ predicate,
+ );
+ match infcx.evaluate_obligation(&obligation) {
+ Ok(eval_result) if eval_result.may_apply() => {}
+ Err(traits::OverflowError::Canonical) => {}
+ Err(traits::OverflowError::ErrorReporting) => {}
+ _ => continue 'blanket_impls,
}
- });
+ }
debug!(
- "get_blanket_impls: found applicable impl: {} for trait_ref={:?}, ty={:?}",
- may_apply, trait_ref, ty
+ "get_blanket_impls: found applicable impl for trait_ref={:?}, ty={:?}",
+ trait_ref, ty
);
- if !may_apply {
- continue;
- }
cx.generated_synthetics.insert((ty.0, trait_def_id));