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Call skolemize_late_bound_regions only after fast rejection #24615

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merged 1 commit into from
Apr 23, 2015
Merged

Call skolemize_late_bound_regions only after fast rejection #24615

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47 changes: 20 additions & 27 deletions src/librustc/middle/traits/select.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -532,11 +532,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
obligation.repr(self.tcx()));

self.infcx.probe(|snapshot| {
let (skol_obligation_trait_ref, skol_map) =
self.infcx().skolemize_late_bound_regions(&obligation.predicate, snapshot);
match self.match_impl(impl_def_id, obligation, snapshot,
&skol_map, skol_obligation_trait_ref.trait_ref.clone()) {
Ok(substs) => {
match self.match_impl(impl_def_id, obligation, snapshot) {
Ok((substs, skol_map)) => {
let vtable_impl = self.vtable_impl(impl_def_id,
substs,
obligation.cause.clone(),
Expand Down Expand Up @@ -1160,10 +1157,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let all_impls = self.all_impls(def_id);
for &impl_def_id in &all_impls {
self.infcx.probe(|snapshot| {
let (skol_obligation_trait_pred, skol_map) =
self.infcx().skolemize_late_bound_regions(&obligation.predicate, snapshot);
match self.match_impl(impl_def_id, obligation, snapshot,
&skol_map, skol_obligation_trait_pred.trait_ref.clone()) {
match self.match_impl(impl_def_id, obligation, snapshot) {
Ok(_) => {
candidates.vec.push(ImplCandidate(impl_def_id));
}
Expand Down Expand Up @@ -2115,11 +2109,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
// First, create the substitutions by matching the impl again,
// this time not in a probe.
self.infcx.commit_if_ok(|snapshot| {
let (skol_obligation_trait_ref, skol_map) =
self.infcx().skolemize_late_bound_regions(&obligation.predicate, snapshot);
let substs =
let (substs, skol_map) =
self.rematch_impl(impl_def_id, obligation,
snapshot, &skol_map, skol_obligation_trait_ref.trait_ref);
snapshot);
debug!("confirm_impl_candidate substs={}", substs.repr(self.tcx()));
Ok(self.vtable_impl(impl_def_id, substs, obligation.cause.clone(),
obligation.recursion_depth + 1, skol_map, snapshot))
Expand Down Expand Up @@ -2306,14 +2298,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
fn rematch_impl(&mut self,
impl_def_id: ast::DefId,
obligation: &TraitObligation<'tcx>,
snapshot: &infer::CombinedSnapshot,
skol_map: &infer::SkolemizationMap,
skol_obligation_trait_ref: Rc<ty::TraitRef<'tcx>>)
-> Normalized<'tcx, Substs<'tcx>>
snapshot: &infer::CombinedSnapshot)
-> (Normalized<'tcx, Substs<'tcx>>, infer::SkolemizationMap)
{
match self.match_impl(impl_def_id, obligation, snapshot,
skol_map, skol_obligation_trait_ref) {
Ok(substs) => substs,
match self.match_impl(impl_def_id, obligation, snapshot) {
Ok((substs, skol_map)) => (substs, skol_map),
Err(()) => {
self.tcx().sess.bug(
&format!("Impl {} was matchable against {} but now is not",
Expand All @@ -2326,10 +2315,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
fn match_impl(&mut self,
impl_def_id: ast::DefId,
obligation: &TraitObligation<'tcx>,
snapshot: &infer::CombinedSnapshot,
skol_map: &infer::SkolemizationMap,
skol_obligation_trait_ref: Rc<ty::TraitRef<'tcx>>)
-> Result<Normalized<'tcx, Substs<'tcx>>, ()>
snapshot: &infer::CombinedSnapshot)
-> Result<(Normalized<'tcx, Substs<'tcx>>,
infer::SkolemizationMap), ()>
{
let impl_trait_ref = ty::impl_trait_ref(self.tcx(), impl_def_id).unwrap();

Expand All @@ -2340,6 +2328,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
return Err(());
}

let (skol_obligation, skol_map) = self.infcx().skolemize_late_bound_regions(
&obligation.predicate,
snapshot);
let skol_obligation_trait_ref = skol_obligation.trait_ref;

let impl_substs = util::fresh_type_vars_for_impl(self.infcx,
obligation.cause.span,
impl_def_id);
Expand Down Expand Up @@ -2370,17 +2363,17 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
return Err(());
}

if let Err(e) = self.infcx.leak_check(skol_map, snapshot) {
if let Err(e) = self.infcx.leak_check(&skol_map, snapshot) {
debug!("match_impl: failed leak check due to `{}`",
ty::type_err_to_str(self.tcx(), &e));
return Err(());
}

debug!("match_impl: success impl_substs={}", impl_substs.repr(self.tcx()));
Ok(Normalized {
Ok((Normalized {
value: impl_substs,
obligations: impl_trait_ref.obligations
})
}, skol_map))
}

fn fast_reject_trait_refs(&mut self,
Expand Down