rustc: use accessors for Substs::{types,regions}.

src/librustc/middle/dead.rs

@@ -95,7 +95,7 @@ impl<'a, 'tcx> MarkSymbolVisitor<'a, 'tcx> {
             Def::AssociatedTy(..) | Def::Method(_) | Def::AssociatedConst(_)
             if self.tcx.trait_of_item(def.def_id()).is_some() => {
                 if let Some(substs) = self.tcx.tables.borrow().item_substs.get(&id) {
-                    match substs.substs.types[0].sty {
+                    match substs.substs.type_at(0).sty {
                         TyEnum(tyid, _) | TyStruct(tyid, _) => {
                             self.check_def_id(tyid.did)
                         }

src/librustc/traits/error_reporting.rs

@@ -232,8 +232,8 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                 if let Ok(..) = self.can_equate(&trait_self_ty, &impl_self_ty) {
                     self_match_impls.push(def_id);
 
-                    if trait_ref.substs.types[1..].iter()
-                        .zip(&impl_trait_ref.substs.types[1..])
+                    if trait_ref.substs.types().skip(1)
+                        .zip(impl_trait_ref.substs.types().skip(1))
                         .all(|(u,v)| self.fuzzy_match_tys(u, v))
                     {
                         fuzzy_match_impls.push(def_id);
@@ -738,8 +738,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             ty::Predicate::Trait(ref data) => {
                 let trait_ref = data.to_poly_trait_ref();
                 let self_ty = trait_ref.self_ty();
-                let all_types = &trait_ref.substs().types;
-                if all_types.references_error() {
+                if predicate.references_error() {
                 } else {
                     // Typically, this ambiguity should only happen if
                     // there are unresolved type inference variables

src/librustc/traits/fulfill.rs

@@ -142,7 +142,7 @@ impl<'a, 'gcx, 'tcx> DeferredObligation<'tcx> {
         // Auto trait obligations on `impl Trait`.
         if tcx.trait_has_default_impl(predicate.def_id()) {
             let substs = predicate.skip_binder().trait_ref.substs;
-            if substs.types.len() == 1 && substs.regions.is_empty() {
+            if substs.types().count() == 1 && substs.regions().next().is_none() {
                 if let ty::TyAnon(..) = predicate.skip_binder().self_ty().sty {
                     return true;
                 }
@@ -440,7 +440,6 @@ fn trait_ref_type_vars<'a, 'gcx, 'tcx>(selcx: &mut SelectionContext<'a, 'gcx, 't
 {
     t.skip_binder() // ok b/c this check doesn't care about regions
      .input_types()
-     .iter()
      .map(|t| selcx.infcx().resolve_type_vars_if_possible(t))
      .filter(|t| t.has_infer_types())
      .flat_map(|t| t.walk())

src/librustc/traits/object_safety.rs

@@ -145,7 +145,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                 match predicate {
                     ty::Predicate::Trait(ref data) => {
                         // In the case of a trait predicate, we can skip the "self" type.
-                        data.0.trait_ref.input_types()[1..].iter().any(|t| t.has_self_ty())
+                        data.skip_binder().input_types().skip(1).any(|t| t.has_self_ty())
                     }
                     ty::Predicate::Projection(..) |
                     ty::Predicate::WellFormed(..) |

src/librustc/traits/select.rs

@@ -644,8 +644,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
         // This suffices to allow chains like `FnMut` implemented in
         // terms of `Fn` etc, but we could probably make this more
         // precise still.
-        let input_types = stack.fresh_trait_ref.0.input_types();
-        let unbound_input_types = input_types.iter().any(|ty| ty.is_fresh());
+        let unbound_input_types = stack.fresh_trait_ref.input_types().any(|ty| ty.is_fresh());
         if unbound_input_types && self.intercrate {
             debug!("evaluate_stack({:?}) --> unbound argument, intercrate -->  ambiguous",
                    stack.fresh_trait_ref);
@@ -1064,9 +1063,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
 
         match *candidate {
             Ok(Some(_)) | Err(_) => true,
-            Ok(None) => {
-                cache_fresh_trait_pred.0.trait_ref.substs.types.has_infer_types()
-            }
+            Ok(None) => cache_fresh_trait_pred.has_infer_types()
         }
     }
 
@@ -1603,7 +1600,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
                 return;
             }
         };
-        let target = obligation.predicate.skip_binder().input_types()[1];
+        let target = obligation.predicate.skip_binder().trait_ref.substs.type_at(1);
 
         debug!("assemble_candidates_for_unsizing(source={:?}, target={:?})",
                source, target);
@@ -1936,7 +1933,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
 
             // for `PhantomData<T>`, we pass `T`
             ty::TyStruct(def, substs) if def.is_phantom_data() => {
-                substs.types.to_vec()
+                substs.types().cloned().collect()
             }
 
             ty::TyStruct(def, substs) | ty::TyEnum(def, substs) => {
@@ -2180,12 +2177,12 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
         match self_ty.sty {
             ty::TyTrait(ref data) => {
                 // OK to skip the binder, it is reintroduced below
-                let input_types = data.principal.skip_binder().input_types();
+                let input_types = data.principal.input_types();
                 let assoc_types = data.projection_bounds.iter()
                                       .map(|pb| pb.skip_binder().ty);
-                let all_types: Vec<_> = input_types.iter().cloned()
-                                                          .chain(assoc_types)
-                                                          .collect();
+                let all_types: Vec<_> = input_types.cloned()
+                                                   .chain(assoc_types)
+                                                   .collect();
 
                 // reintroduce the two binding levels we skipped, then flatten into one
                 let all_types = ty::Binder(ty::Binder(all_types));
@@ -2476,7 +2473,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
         // regions here. See the comment there for more details.
         let source = self.infcx.shallow_resolve(
             tcx.no_late_bound_regions(&obligation.self_ty()).unwrap());
-        let target = obligation.predicate.skip_binder().input_types()[1];
+        let target = obligation.predicate.skip_binder().trait_ref.substs.type_at(1);
         let target = self.infcx.shallow_resolve(target);
 
         debug!("confirm_builtin_unsize_candidate(source={:?}, target={:?})",
@@ -2585,7 +2582,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
                 } else {
                     return Err(Unimplemented);
                 };
-                let mut ty_params = BitVector::new(substs_a.types.len());
+                let mut ty_params = BitVector::new(substs_a.types().count());
                 let mut found = false;
                 for ty in field.walk() {
                     if let ty::TyParam(p) = ty.sty {
@@ -2601,14 +2598,14 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
                 // TyError and ensure they do not affect any other fields.
                 // This could be checked after type collection for any struct
                 // with a potentially unsized trailing field.
-                let types = substs_a.types.iter().enumerate().map(|(i, ty)| {
+                let types = substs_a.types().enumerate().map(|(i, ty)| {
                     if ty_params.contains(i) {
                         tcx.types.err
                     } else {
                         ty
                     }
                 }).collect();
-                let substs = Substs::new(tcx, types, substs_a.regions.clone());
+                let substs = Substs::new(tcx, types, substs_a.regions().cloned().collect());
                 for &ty in fields.split_last().unwrap().1 {
                     if ty.subst(tcx, substs).references_error() {
                         return Err(Unimplemented);
@@ -2621,14 +2618,14 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
 
                 // Check that the source structure with the target's
                 // type parameters is a subtype of the target.
-                let types = substs_a.types.iter().enumerate().map(|(i, ty)| {
+                let types = substs_a.types().enumerate().map(|(i, ty)| {
                     if ty_params.contains(i) {
-                        substs_b.types[i]
+                        substs_b.type_at(i)
                     } else {
                         ty
                     }
                 }).collect();
-                let substs = Substs::new(tcx, types, substs_a.regions.clone());
+                let substs = Substs::new(tcx, types, substs_a.regions().cloned().collect());
                 let new_struct = tcx.mk_struct(def, substs);
                 let origin = TypeOrigin::Misc(obligation.cause.span);
                 let InferOk { obligations, .. } =
@@ -2753,7 +2750,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
         // substitution if we find that any of the input types, when
         // simplified, do not match.
 
-        obligation.predicate.0.input_types().iter()
+        obligation.predicate.skip_binder().input_types()
             .zip(impl_trait_ref.input_types())
             .any(|(&obligation_ty, &impl_ty)| {
                 let simplified_obligation_ty =

src/librustc/ty/context.rs

@@ -1152,7 +1152,7 @@ fn keep_local<'tcx, T: ty::TypeFoldable<'tcx>>(x: &T) -> bool {
 impl_interners!('tcx,
     type_list: mk_type_list(Vec<Ty<'tcx>>, keep_local) -> [Ty<'tcx>],
     substs: mk_substs(Substs<'tcx>, |substs: &Substs| {
-        keep_local(&substs.types) || keep_local(&substs.regions)
+        substs.types().any(keep_local) || substs.regions().any(keep_local)
     }) -> Substs<'tcx>,
     bare_fn: mk_bare_fn(BareFnTy<'tcx>, |fty: &BareFnTy| {
         keep_local(&fty.sig)

src/librustc/ty/flags.rs

@@ -208,8 +208,11 @@ impl FlagComputation {
     }
 
     fn add_substs(&mut self, substs: &Substs) {
-        self.add_tys(&substs.types);
-        for &r in &substs.regions {
+        for &ty in substs.types() {
+            self.add_ty(ty);
+        }
+
+        for &r in substs.regions() {
             self.add_region(r);
         }
     }

src/librustc/ty/item_path.rs

@@ -264,7 +264,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         match self_ty.sty {
             ty::TyStruct(adt_def, substs) |
             ty::TyEnum(adt_def, substs) => {
-                if substs.types.is_empty() { // ignore regions
+                if substs.types().next().is_none() { // ignore regions
                     self.push_item_path(buffer, adt_def.did);
                 } else {
                     buffer.push(&format!("<{}>", self_ty));

src/librustc/ty/mod.rs

@@ -951,7 +951,6 @@ impl<'tcx> TraitPredicate<'tcx> {
         // leads to more recompilation.
         let def_ids: Vec<_> =
             self.input_types()
-                .iter()
                 .flat_map(|t| t.walk())
                 .filter_map(|t| match t.sty {
                     ty::TyStruct(adt_def, _) |
@@ -964,8 +963,8 @@ impl<'tcx> TraitPredicate<'tcx> {
         DepNode::TraitSelect(self.def_id(), def_ids)
     }
 
-    pub fn input_types(&self) -> &[Ty<'tcx>] {
-        &self.trait_ref.substs.types
+    pub fn input_types(&self) -> slice::Iter<Ty<'tcx>> {
+        self.trait_ref.input_types()
     }
 
     pub fn self_ty(&self) -> Ty<'tcx> {
@@ -1107,7 +1106,7 @@ impl<'tcx> Predicate<'tcx> {
     pub fn walk_tys(&self) -> IntoIter<Ty<'tcx>> {
         let vec: Vec<_> = match *self {
             ty::Predicate::Trait(ref data) => {
-                data.0.trait_ref.input_types().to_vec()
+                data.skip_binder().input_types().cloned().collect()
             }
             ty::Predicate::Rfc1592(ref data) => {
                 return data.walk_tys()
@@ -1123,8 +1122,7 @@ impl<'tcx> Predicate<'tcx> {
             }
             ty::Predicate::Projection(ref data) => {
                 let trait_inputs = data.0.projection_ty.trait_ref.input_types();
-                trait_inputs.iter()
-                            .cloned()
+                trait_inputs.cloned()
                             .chain(Some(data.0.ty))
                             .collect()
             }
@@ -1206,15 +1204,15 @@ impl<'tcx> TraitRef<'tcx> {
     }
 
     pub fn self_ty(&self) -> Ty<'tcx> {
-        self.substs.types[0]
+        self.substs.type_at(0)
     }
 
-    pub fn input_types(&self) -> &[Ty<'tcx>] {
+    pub fn input_types(&self) -> slice::Iter<Ty<'tcx>> {
         // Select only the "input types" from a trait-reference. For
         // now this is all the types that appear in the
         // trait-reference, but it should eventually exclude
         // associated types.
-        &self.substs.types
+        self.substs.types()
     }
 }
 

src/librustc/ty/relate.rs

@@ -147,14 +147,12 @@ pub fn relate_substs<'a, 'gcx, 'tcx, R>(relation: &mut R,
 {
     let tcx = relation.tcx();
 
-    let types = a_subst.types.iter().enumerate().map(|(i, a_ty)| {
-        let b_ty = &b_subst.types[i];
+    let types = a_subst.types().zip(b_subst.types()).enumerate().map(|(i, (a_ty, b_ty))| {
         let variance = variances.map_or(ty::Invariant, |v| v.types[i]);
         relation.relate_with_variance(variance, a_ty, b_ty)
     }).collect::<Result<_, _>>()?;
 
-    let regions = a_subst.regions.iter().enumerate().map(|(i, a_r)| {
-        let b_r = &b_subst.regions[i];
+    let regions = a_subst.regions().zip(b_subst.regions()).enumerate().map(|(i, (a_r, b_r))| {
         let variance = variances.map_or(ty::Invariant, |v| v.regions[i]);
         relation.relate_with_variance(variance, a_r, b_r)
     }).collect::<Result<_, _>>()?;

src/librustc/ty/structural_impls.rs

@@ -9,7 +9,6 @@
 // except according to those terms.
 
 use infer::type_variable;
-use ty::subst::Substs;
 use ty::{self, Lift, Ty, TyCtxt};
 use ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
 
@@ -692,22 +691,6 @@ impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::Region {
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for &'tcx Substs<'tcx> {
-    fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
-        let types = self.types.fold_with(folder);
-        let regions = self.regions.fold_with(folder);
-        Substs::new(folder.tcx(), types, regions)
-    }
-
-    fn fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
-        folder.fold_substs(self)
-    }
-
-    fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
-        self.types.visit_with(visitor) || self.regions.visit_with(visitor)
-    }
-}
-
 impl<'tcx> TypeFoldable<'tcx> for ty::ClosureSubsts<'tcx> {
     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
         ty::ClosureSubsts {

src/librustc/ty/sty.rs

@@ -19,8 +19,9 @@ use util::common::ErrorReported;
 
 use collections::enum_set::{self, EnumSet, CLike};
 use std::fmt;
-use std::ops;
 use std::mem;
+use std::ops;
+use std::slice;
 use syntax::abi;
 use syntax::ast::{self, Name};
 use syntax::parse::token::keywords;
@@ -335,7 +336,7 @@ impl<'tcx> PolyTraitRef<'tcx> {
         self.0.substs
     }
 
-    pub fn input_types(&self) -> &[Ty<'tcx>] {
+    pub fn input_types(&self) -> slice::Iter<Ty<'tcx>> {
         // FIXME(#20664) every use of this fn is probably a bug, it should yield Binder<>
         self.0.input_types()
     }
@@ -360,12 +361,12 @@ pub struct ExistentialTraitRef<'tcx> {
 }
 
 impl<'tcx> ExistentialTraitRef<'tcx> {
-    pub fn input_types(&self) -> &[Ty<'tcx>] {
+    pub fn input_types(&self) -> slice::Iter<Ty<'tcx>>{
         // Select only the "input types" from a trait-reference. For
         // now this is all the types that appear in the
         // trait-reference, but it should eventually exclude
         // associated types.
-        &self.substs.types
+        self.substs.types()
     }
 }
 
@@ -376,7 +377,7 @@ impl<'tcx> PolyExistentialTraitRef<'tcx> {
         self.0.def_id
     }
 
-    pub fn input_types(&self) -> &[Ty<'tcx>] {
+    pub fn input_types(&self) -> slice::Iter<Ty<'tcx>> {
         // FIXME(#20664) every use of this fn is probably a bug, it should yield Binder<>
         self.0.input_types()
     }
@@ -1213,19 +1214,19 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
             }
             TyTrait(ref obj) => {
                 let mut v = vec![obj.region_bound];
-                v.extend_from_slice(&obj.principal.skip_binder().substs.regions);
+                v.extend(obj.principal.skip_binder().substs.regions());
                 v
             }
             TyEnum(_, substs) |
             TyStruct(_, substs) |
             TyAnon(_, substs) => {
-                substs.regions.to_vec()
+                substs.regions().cloned().collect()
             }
             TyClosure(_, ref substs) => {
-                substs.func_substs.regions.to_vec()
+                substs.func_substs.regions().cloned().collect()
             }
             TyProjection(ref data) => {
-                data.trait_ref.substs.regions.to_vec()
+                data.trait_ref.substs.regions().cloned().collect()
             }
             TyFnDef(..) |
             TyFnPtr(_) |