diff --git a/src/librustc/middle/traits/project.rs b/src/librustc/middle/traits/project.rs
index 43f97de2d43..d319e441415 100644
--- a/src/librustc/middle/traits/project.rs
+++ b/src/librustc/middle/traits/project.rs
@@ -222,9 +222,10 @@ fn assemble_candidates_from_object_type<'cx,'tcx>(
         ty::ty_trait(ref data) => data,
         _ => { return; }
     };
-    let env_predicates = data.projection_bounds_with_self_ty(self_ty).iter()
-                                                                     .map(|p| p.as_predicate())
-                                                                     .collect();
+    let projection_bounds = data.projection_bounds_with_self_ty(selcx.tcx(), self_ty);
+    let env_predicates = projection_bounds.iter()
+                                          .map(|p| p.as_predicate())
+                                          .collect();
     assemble_candidates_from_predicates(selcx, obligation, candidate_set, env_predicates)
 }
 
diff --git a/src/librustc/middle/traits/select.rs b/src/librustc/middle/traits/select.rs
index 9670ebdb03c..91f1b50521d 100644
--- a/src/librustc/middle/traits/select.rs
+++ b/src/librustc/middle/traits/select.rs
@@ -791,7 +791,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                projection_trait_ref.repr(self.tcx()));
 
         let trait_def = ty::lookup_trait_def(self.tcx(), projection_trait_ref.def_id);
-        let bounds = trait_def.generics.to_bounds(self.tcx(), &projection_trait_ref.substs);
+        let bounds = trait_def.generics.to_bounds(self.tcx(), projection_trait_ref.substs);
         debug!("match_projection_obligation_against_bounds_from_trait: \
                 bounds={}",
                bounds.repr(self.tcx()));
diff --git a/src/librustc/middle/ty.rs b/src/librustc/middle/ty.rs
index 0f3037c06fd..caec56800c6 100644
--- a/src/librustc/middle/ty.rs
+++ b/src/librustc/middle/ty.rs
@@ -914,7 +914,7 @@ impl<'tcx> ctxt<'tcx> {
         sty_debug_print!(
             self,
             ty_enum, ty_uniq, ty_vec, ty_ptr, ty_rptr, ty_bare_fn, ty_closure, ty_trait,
-            ty_struct, ty_unboxed_closure, ty_tup, ty_param, ty_open, ty_infer);
+            ty_struct, ty_unboxed_closure, ty_tup, ty_param, ty_open, ty_infer, ty_projection);
 
         println!("Substs interner: #{}", self.substs_interner.borrow().len());
         println!("BareFnTy interner: #{}", self.bare_fn_interner.borrow().len());
@@ -1352,7 +1352,7 @@ pub enum sty<'tcx> {
 
     ty_closure(Box<ClosureTy<'tcx>>),
     ty_trait(Box<TyTrait<'tcx>>),
-    ty_struct(DefId, Substs<'tcx>),
+    ty_struct(DefId, &'tcx Substs<'tcx>),
 
     ty_unboxed_closure(DefId, &'tcx Region, &'tcx Substs<'tcx>),
 
@@ -1402,7 +1402,9 @@ impl<'tcx> TyTrait<'tcx> {
         }))
     }
 
-    pub fn projection_bounds_with_self_ty(&self, self_ty: Ty<'tcx>)
+    pub fn projection_bounds_with_self_ty(&self,
+                                          tcx: &ctxt<'tcx>,
+                                          self_ty: Ty<'tcx>)
                                           -> Vec<ty::PolyProjectionPredicate<'tcx>>
     {
         // otherwise the escaping regions would be captured by the binders
@@ -1411,10 +1413,10 @@ impl<'tcx> TyTrait<'tcx> {
         self.bounds.projection_bounds.iter()
             .map(|in_poly_projection_predicate| {
                 let in_projection_ty = &in_poly_projection_predicate.0.projection_ty;
+                let substs = tcx.mk_substs(in_projection_ty.trait_ref.substs.with_self_ty(self_ty));
                 let trait_ref =
-                    Rc::new(ty::TraitRef::new(
-                        in_projection_ty.trait_ref.def_id,
-                        in_projection_ty.trait_ref.substs.with_self_ty(self_ty)));
+                    Rc::new(ty::TraitRef::new(in_projection_ty.trait_ref.def_id,
+                                              substs));
                 let projection_ty = ty::ProjectionTy {
                     trait_ref: trait_ref,
                     item_name: in_projection_ty.item_name
@@ -2286,7 +2288,7 @@ pub fn mk_ctxt<'tcx>(s: Session,
 
     ctxt {
         arenas: arenas,
-        interner: RefCell::new(FnvHashMap::new()),
+        interner: RefCell::new(interner),
         substs_interner: RefCell::new(FnvHashMap::new()),
         bare_fn_interner: RefCell::new(FnvHashMap::new()),
         region_interner: RefCell::new(FnvHashMap::new()),
@@ -2386,7 +2388,7 @@ impl<'tcx> ctxt<'tcx> {
 // and returns the box as cast to an unsafe ptr (see comments for Ty above).
 pub fn mk_t<'tcx>(cx: &ctxt<'tcx>, st: sty<'tcx>) -> Ty<'tcx> {
     let mut interner = cx.interner.borrow_mut();
-    intern_ty(cx.type_arena, &mut *interner, st)
+    intern_ty(&cx.arenas.type_, &mut *interner, st)
 }
 
 fn intern_ty<'tcx>(type_arena: &'tcx TypedArena<TyS<'tcx>>,
@@ -2501,12 +2503,12 @@ impl FlagComputation {
 
             &ty_projection(ref data) => {
                 self.add_flags(HAS_PROJECTION);
-                self.add_substs(&data.trait_ref.substs);
+                self.add_substs(data.trait_ref.substs);
             }
 
             &ty_trait(box TyTrait { ref principal, ref bounds }) => {
                 let mut computation = FlagComputation::new();
-                computation.add_substs(&principal.0.substs);
+                computation.add_substs(principal.0.substs);
                 self.add_bound_computation(&computation);
 
                 self.add_bounds(bounds);
diff --git a/src/librustc_trans/trans/debuginfo.rs b/src/librustc_trans/trans/debuginfo.rs
index e94ce55e704..b5b1c6ff864 100644
--- a/src/librustc_trans/trans/debuginfo.rs
+++ b/src/librustc_trans/trans/debuginfo.rs
@@ -428,7 +428,7 @@ impl<'tcx> TypeMap<'tcx> {
                 from_def_id_and_substs(self,
                                        cx,
                                        trait_data.principal_def_id(),
-                                       &trait_data.principal.0.substs,
+                                       trait_data.principal.0.substs,
                                        &mut unique_type_id);
             },
             ty::ty_bare_fn(_, &ty::BareFnTy{ unsafety, abi, ref sig } ) => {
@@ -3819,7 +3819,7 @@ fn push_debuginfo_type_name<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
         },
         ty::ty_trait(ref trait_data) => {
             push_item_name(cx, trait_data.principal_def_id(), false, output);
-            push_type_params(cx, &trait_data.principal.0.substs, output);
+            push_type_params(cx, trait_data.principal.0.substs, output);
         },
         ty::ty_bare_fn(_, &ty::BareFnTy{ unsafety, abi, ref sig } ) => {
             if unsafety == ast::Unsafety::Unsafe {
diff --git a/src/librustc_trans/trans/expr.rs b/src/librustc_trans/trans/expr.rs
index 5a7131cf68e..5a20a297fdb 100644
--- a/src/librustc_trans/trans/expr.rs
+++ b/src/librustc_trans/trans/expr.rs
@@ -321,7 +321,7 @@ fn apply_adjustments<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
             &ty::UnsizeVtable(ty::TyTrait { ref principal, .. }, _) => {
                 // Note that we preserve binding levels here:
                 let substs = principal.0.substs.with_self_ty(unadjusted_ty).erase_regions();
-                let substs = tcx.tcx().mk_substs(substs);
+                let substs = bcx.tcx().mk_substs(substs);
                 let trait_ref =
                     ty::Binder(Rc::new(ty::TraitRef { def_id: principal.def_id(),
                                                       substs: substs }));
diff --git a/src/librustc_trans/trans/monomorphize.rs b/src/librustc_trans/trans/monomorphize.rs
index 6e52454fa78..3b7043e4f40 100644
--- a/src/librustc_trans/trans/monomorphize.rs
+++ b/src/librustc_trans/trans/monomorphize.rs
@@ -348,6 +348,7 @@ impl<'a,'tcx> TypeFolder<'tcx> for AssociatedTypeNormalizer<'a,'tcx> {
 
                 let tcx = self.selcx.tcx();
                 let substs = data.trait_ref.substs.clone().erase_regions();
+                let substs = self.tcx().mk_substs(substs);
                 assert!(substs.types.iter().all(|&t| (!ty::type_has_params(t) &&
                                                       !ty::type_has_self(t))));
                 let trait_ref = Rc::new(ty::TraitRef::new(data.trait_ref.def_id, substs));
diff --git a/src/librustc_typeck/check/closure.rs b/src/librustc_typeck/check/closure.rs
index 340cc9b355c..85ead053d1d 100644
--- a/src/librustc_typeck/check/closure.rs
+++ b/src/librustc_typeck/check/closure.rs
@@ -172,7 +172,9 @@ fn deduce_unboxed_closure_expectations_from_expected_type<'a,'tcx>(
 {
     match expected_ty.sty {
         ty::ty_trait(ref object_type) => {
-            let trait_ref = object_type.principal_trait_ref_with_self_ty(fcx.tcx().types.err);
+            let trait_ref =
+                object_type.principal_trait_ref_with_self_ty(fcx.tcx(),
+                                                             fcx.tcx().types.err);
             deduce_unboxed_closure_expectations_from_trait_ref(fcx, &trait_ref)
         }
         ty::ty_infer(ty::TyVar(vid)) => {
diff --git a/src/librustc_typeck/check/method/mod.rs b/src/librustc_typeck/check/method/mod.rs
index 5b6acdbf3ad..e4836094071 100644
--- a/src/librustc_typeck/check/method/mod.rs
+++ b/src/librustc_typeck/check/method/mod.rs
@@ -199,7 +199,7 @@ pub fn lookup_in_trait_adjusted<'a, 'tcx>(fcx: &'a FnCtxt<'a, 'tcx>,
     let fn_sig = fcx.infcx().replace_late_bound_regions_with_fresh_var(span,
                                                                        infer::FnCall,
                                                                        &method_ty.fty.sig).0;
-    let fn_sig = fcx.instantiate_type_scheme(span, &trait_ref.substs, &fn_sig);
+    let fn_sig = fcx.instantiate_type_scheme(span, trait_ref.substs, &fn_sig);
     let transformed_self_ty = fn_sig.inputs[0];
     let fty = ty::mk_bare_fn(tcx, None, tcx.mk_bare_fn(ty::BareFnTy {
         sig: ty::Binder(fn_sig),
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index e485e49148f..a11f7b15e03 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -1194,9 +1194,12 @@ fn compare_impl_method<'tcx>(tcx: &ty::ctxt<'tcx>,
                                                  impl_m_span,
                                                  impl_m_body_id,
                                                  &impl_sig);
-        let impl_fty = ty::mk_bare_fn(tcx, None, ty::BareFnTy { unsafety: impl_m.fty.unsafety,
-                                                                abi: impl_m.fty.abi,
-                                                                sig: ty::Binder(impl_sig) });
+        let impl_fty =
+            ty::mk_bare_fn(tcx,
+                           None,
+                           tcx.mk_bare_fn(ty::BareFnTy { unsafety: impl_m.fty.unsafety,
+                                                         abi: impl_m.fty.abi,
+                                                         sig: ty::Binder(impl_sig) }));
         debug!("compare_impl_method: impl_fty={}",
                impl_fty.repr(tcx));
 
@@ -1210,9 +1213,12 @@ fn compare_impl_method<'tcx>(tcx: &ty::ctxt<'tcx>,
                                                  impl_m_span,
                                                  impl_m_body_id,
                                                  &trait_sig);
-        let trait_fty = ty::mk_bare_fn(tcx, None, ty::BareFnTy { unsafety: trait_m.fty.unsafety,
-                                                                 abi: trait_m.fty.abi,
-                                                                 sig: ty::Binder(trait_sig) });
+        let trait_fty =
+            ty::mk_bare_fn(tcx,
+                           None,
+                           tcx.mk_bare_fn(ty::BareFnTy { unsafety: trait_m.fty.unsafety,
+                                                         abi: trait_m.fty.abi,
+                                                         sig: ty::Binder(trait_sig) }));
 
         debug!("compare_impl_method: trait_fty={}",
                trait_fty.repr(tcx));
diff --git a/src/librustc_typeck/check/regionmanip.rs b/src/librustc_typeck/check/regionmanip.rs
index 8d9e241e73b..bb051ab1525 100644
--- a/src/librustc_typeck/check/regionmanip.rs
+++ b/src/librustc_typeck/check/regionmanip.rs
@@ -131,7 +131,7 @@ impl<'a, 'tcx> Wf<'a, 'tcx> {
                 // this seems like a minimal requirement:
                 let trait_def = ty::lookup_trait_def(self.tcx, data.trait_ref.def_id);
                 self.accumulate_from_adt(ty, data.trait_ref.def_id,
-                                         &trait_def.generics, &data.trait_ref.substs)
+                                         &trait_def.generics, data.trait_ref.substs)
             }
 
             ty::ty_tup(ref tuptys) => {
diff --git a/src/librustc_typeck/check/vtable.rs b/src/librustc_typeck/check/vtable.rs
index f5cbfcdcc52..23a8643aadc 100644
--- a/src/librustc_typeck/check/vtable.rs
+++ b/src/librustc_typeck/check/vtable.rs
@@ -389,7 +389,8 @@ pub fn register_object_cast_obligations<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
     }
 
     // Finally, create obligations for the projection predicates.
-    let projection_bounds = object_trait.projection_bounds_with_self_ty(referent_ty);
+    let projection_bounds =
+        object_trait.projection_bounds_with_self_ty(fcx.tcx(), referent_ty);
     for projection_bound in projection_bounds.iter() {
         let projection_obligation =
             Obligation::new(cause.clone(), projection_bound.as_predicate());
diff --git a/src/librustc_typeck/collect.rs b/src/librustc_typeck/collect.rs
index 1187baa9a9c..da591ca04b7 100644
--- a/src/librustc_typeck/collect.rs
+++ b/src/librustc_typeck/collect.rs
@@ -838,8 +838,6 @@ pub fn trait_def_of_item<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
                                             generics,
                                             items);
 
-    assert_eq!(mk_item_substs(ccx, &ty_generics), substs);
-
     let self_param_ty = ty::ParamTy::for_self();
 
     let bounds = compute_bounds(ccx,
@@ -1476,7 +1474,7 @@ pub fn ty_of_foreign_fn_decl<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
             sig: ty::Binder(ty::FnSig {inputs: input_tys,
                                        output: output,
                                        variadic: decl.variadic}),
-        });
+        }));
     let scheme = TypeScheme {
         generics: ty_generics_for_fn_or_method,
         ty: t_fn
diff --git a/src/librustc_typeck/variance.rs b/src/librustc_typeck/variance.rs
index 2914895aa7a..c4c33f24f87 100644
--- a/src/librustc_typeck/variance.rs
+++ b/src/librustc_typeck/variance.rs
@@ -787,12 +787,13 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
                     trait_ref.def_id,
                     trait_def.generics.types.as_slice(),
                     trait_def.generics.regions.as_slice(),
-                    &trait_ref.substs,
+                    trait_ref.substs,
                     variance);
             }
 
             ty::ty_trait(ref data) => {
-                let trait_ref = data.principal_trait_ref_with_self_ty(self.tcx().types.err);
+                let trait_ref = data.principal_trait_ref_with_self_ty(self.tcx(),
+                                                                      self.tcx().types.err);
                 let trait_def = ty::lookup_trait_def(self.tcx(), trait_ref.def_id());
 
                 // Traits never declare region parameters in the self
@@ -815,7 +816,7 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
             }
 
             ty::ty_param(ref data) => {
-                let def_id = generics.types.get(data.space, data.idx).def_id;
+                let def_id = generics.types.get(data.space, data.idx as uint).def_id;
                 assert_eq!(def_id.krate, ast::LOCAL_CRATE);
                 match self.terms_cx.inferred_map.get(&def_id.node) {
                     Some(&index) => {