1 files changed, 8 insertions, 7 deletions
diff --git a/src/librustc/traits/util.rs b/src/librustc/traits/util.rs
index 7c273fb14db..3a882506b41 100644
--- a/src/librustc/traits/util.rs
+++ b/src/librustc/traits/util.rs
@@ -59,7 +59,7 @@ struct PredicateSet<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
 
 impl<'a, 'gcx, 'tcx> PredicateSet<'a, 'gcx, 'tcx> {
     fn new(tcx: TyCtxt<'a, 'gcx, 'tcx>) -> PredicateSet<'a, 'gcx, 'tcx> {
-        PredicateSet { tcx: tcx, set: FxHashSet() }
+        PredicateSet { tcx: tcx, set: Default::default() }
     }
 
     fn insert(&mut self, pred: &ty::Predicate<'tcx>) -> bool {
@@ -103,11 +103,10 @@ pub fn elaborate_trait_ref<'cx, 'gcx, 'tcx>(
 
 pub fn elaborate_trait_refs<'cx, 'gcx, 'tcx>(
     tcx: TyCtxt<'cx, 'gcx, 'tcx>,
-    trait_refs: &[ty::PolyTraitRef<'tcx>])
+    trait_refs: impl Iterator<Item = ty::PolyTraitRef<'tcx>>)
     -> Elaborator<'cx, 'gcx, 'tcx>
 {
-    let predicates = trait_refs.iter()
-                               .map(|trait_ref| trait_ref.to_predicate())
+    let predicates = trait_refs.map(|trait_ref| trait_ref.to_predicate())
                                .collect();
     elaborate_predicates(tcx, predicates)
 }
@@ -201,8 +200,10 @@ impl<'cx, 'gcx, 'tcx> Elaborator<'cx, 'gcx, 'tcx> {
                 }
 
                 let visited = &mut self.visited;
+                let mut components = smallvec![];
+                tcx.push_outlives_components(ty_max, &mut components);
                 self.stack.extend(
-                    tcx.outlives_components(ty_max)
+                    components
                        .into_iter()
                        .filter_map(|component| match component {
                            Component::Region(r) => if r.is_late_bound() {
@@ -271,7 +272,7 @@ pub fn supertraits<'cx, 'gcx, 'tcx>(tcx: TyCtxt<'cx, 'gcx, 'tcx>,
 }
 
 pub fn transitive_bounds<'cx, 'gcx, 'tcx>(tcx: TyCtxt<'cx, 'gcx, 'tcx>,
-                                          bounds: &[ty::PolyTraitRef<'tcx>])
+                                          bounds: impl Iterator<Item = ty::PolyTraitRef<'tcx>>)
                                           -> Supertraits<'cx, 'gcx, 'tcx>
 {
     elaborate_trait_refs(tcx, bounds).filter_to_traits()
@@ -334,7 +335,7 @@ impl<I> FilterToTraits<I> {
     }
 }
 
-impl<'tcx,I:Iterator<Item=ty::Predicate<'tcx>>> Iterator for FilterToTraits<I> {
+impl<'tcx, I: Iterator<Item = ty::Predicate<'tcx>>> Iterator for FilterToTraits<I> {
     type Item = ty::PolyTraitRef<'tcx>;
 
     fn next(&mut self) -> Option<ty::PolyTraitRef<'tcx>> {