Accept ?Sized as well as Sized?

src/librustc/lint/builtin.rs

@@ -1782,9 +1782,9 @@ impl LintPass for Stability {
         if self.is_internal(cx, item.span) { return }
 
         match item.node {
-            ast::ItemTrait(_, _, _, ref supertraits, _) => {
+            ast::ItemTrait(_, _, ref supertraits, _) => {
                 for t in supertraits.iter() {
-                    if let ast::TraitTyParamBound(ref t) = *t {
+                    if let ast::TraitTyParamBound(ref t, _) = *t {
                         let id = ty::trait_ref_to_def_id(cx.tcx, &t.trait_ref);
                         self.lint(cx, id, t.trait_ref.path.span);
                     }

src/librustc/metadata/encoder.rs

@@ -1308,7 +1308,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
             }
         }
       }
-      ast::ItemTrait(_, _, _, _, ref ms) => {
+      ast::ItemTrait(_, _, _, ref ms) => {
         add_to_index(item, rbml_w, index);
         rbml_w.start_tag(tag_items_data_item);
         encode_def_id(rbml_w, def_id);

src/librustc/middle/infer/error_reporting.rs

@@ -1043,7 +1043,6 @@ impl<'a, 'tcx> Rebuilder<'a, 'tcx> {
                 ident: ty_param.ident,
                 id: ty_param.id,
                 bounds: bounds,
-                unbound: ty_param.unbound.clone(),
                 default: ty_param.default.clone(),
                 span: ty_param.span,
             }
@@ -1063,7 +1062,7 @@ impl<'a, 'tcx> Rebuilder<'a, 'tcx> {
                     // be passing down a map.
                     ast::RegionTyParamBound(lt)
                 }
-                &ast::TraitTyParamBound(ref poly_tr) => {
+                &ast::TraitTyParamBound(ref poly_tr, modifier) => {
                     let tr = &poly_tr.trait_ref;
                     let last_seg = tr.path.segments.last().unwrap();
                     let mut insert = Vec::new();
@@ -1087,7 +1086,7 @@ impl<'a, 'tcx> Rebuilder<'a, 'tcx> {
                             path: new_path,
                             ref_id: tr.ref_id,
                         }
-                    })
+                    }, modifier)
                 }
             }
         })

src/librustc/middle/privacy.rs

@@ -122,7 +122,7 @@ impl<'v> Visitor<'v> for ParentVisitor {
             // method to the root. In this case, if the trait is private, then
             // parent all the methods to the trait to indicate that they're
             // private.
-            ast::ItemTrait(_, _, _, _, ref methods) if item.vis != ast::Public => {
+            ast::ItemTrait(_, _, _, ref methods) if item.vis != ast::Public => {
                 for m in methods.iter() {
                     match *m {
                         ast::ProvidedMethod(ref m) => {
@@ -328,7 +328,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for EmbargoVisitor<'a, 'tcx> {
 
             // Default methods on traits are all public so long as the trait
             // is public
-            ast::ItemTrait(_, _, _, _, ref methods) if public_first => {
+            ast::ItemTrait(_, _, _, ref methods) if public_first => {
                 for method in methods.iter() {
                     match *method {
                         ast::ProvidedMethod(ref m) => {
@@ -1178,7 +1178,7 @@ impl<'a, 'tcx> SanePrivacyVisitor<'a, 'tcx> {
                 }
             }
 
-            ast::ItemTrait(_, _, _, _, ref methods) => {
+            ast::ItemTrait(_, _, _, ref methods) => {
                 for m in methods.iter() {
                     match *m {
                         ast::ProvidedMethod(ref m) => {
@@ -1242,7 +1242,7 @@ impl<'a, 'tcx> SanePrivacyVisitor<'a, 'tcx> {
 
             ast::ItemStruct(ref def, _) => check_struct(&**def),
 
-            ast::ItemTrait(_, _, _, _, ref methods) => {
+            ast::ItemTrait(_, _, _, ref methods) => {
                 for m in methods.iter() {
                     match *m {
                         ast::RequiredMethod(..) => {}
@@ -1306,7 +1306,7 @@ impl<'a, 'tcx> VisiblePrivateTypesVisitor<'a, 'tcx> {
 
     fn check_ty_param_bound(&self,
                             ty_param_bound: &ast::TyParamBound) {
-        if let ast::TraitTyParamBound(ref trait_ref) = *ty_param_bound {
+        if let ast::TraitTyParamBound(ref trait_ref, _) = *ty_param_bound {
             if !self.tcx.sess.features.borrow().visible_private_types &&
                 self.path_is_private_type(trait_ref.trait_ref.ref_id) {
                     let span = trait_ref.trait_ref.path.span;
@@ -1349,7 +1349,7 @@ impl<'a, 'tcx, 'v> Visitor<'v> for VisiblePrivateTypesVisitor<'a, 'tcx> {
             // namespace (the contents have their own privacies).
             ast::ItemForeignMod(_) => {}
 
-            ast::ItemTrait(_, _, _, ref bounds, _) => {
+            ast::ItemTrait(_, _, ref bounds, _) => {
                 if !self.trait_is_public(item.id) {
                     return
                 }

src/librustc/middle/resolve_lifetime.rs

@@ -105,7 +105,7 @@ impl<'a, 'v> Visitor<'v> for LifetimeContext<'a> {
                 ast::ItemTy(_, ref generics) |
                 ast::ItemEnum(_, ref generics) |
                 ast::ItemStruct(_, ref generics) |
-                ast::ItemTrait(_, ref generics, _, _, _) |
+                ast::ItemTrait(_, ref generics, _, _) |
                 ast::ItemImpl(_, ref generics, _, _, _) => {
                     // These kinds of items have only early bound lifetime parameters.
                     let lifetimes = &generics.lifetimes;
@@ -232,7 +232,9 @@ impl<'a, 'v> Visitor<'v> for LifetimeContext<'a> {
         }
     }
 
-    fn visit_poly_trait_ref(&mut self, trait_ref: &ast::PolyTraitRef) {
+    fn visit_poly_trait_ref(&mut self, trait_ref:
+                            &ast::PolyTraitRef,
+                            _modifier: &ast::TraitBoundModifier) {
         debug!("visit_poly_trait_ref trait_ref={}", trait_ref);
 
         self.with(LateScope(&trait_ref.bound_lifetimes, self.scope), |old_scope, this| {

src/librustc/middle/ty.rs

@@ -4608,7 +4608,7 @@ pub fn provided_trait_methods<'tcx>(cx: &ctxt<'tcx>, id: ast::DefId)
         match cx.map.find(id.node) {
             Some(ast_map::NodeItem(item)) => {
                 match item.node {
-                    ItemTrait(_, _, _, _, ref ms) => {
+                    ItemTrait(_, _, _, ref ms) => {
                         let (_, p) =
                             ast_util::split_trait_methods(ms[]);
                         p.iter()

src/librustc_resolve/lib.rs

@@ -1459,7 +1459,7 @@ impl<'a> Resolver<'a> {
 
             ItemImpl(_, _, Some(_), _, _) => parent,
 
-            ItemTrait(_, _, _, _, ref items) => {
+            ItemTrait(_, _, _, ref items) => {
                 let name_bindings =
                     self.add_child(name,
                                    parent.clone(),
@@ -3998,7 +3998,7 @@ impl<'a> Resolver<'a> {
                                             impl_items[]);
             }
 
-            ItemTrait(_, ref generics, ref unbound, ref bounds, ref trait_items) => {
+            ItemTrait(_, ref generics, ref bounds, ref trait_items) => {
                 // Create a new rib for the self type.
                 let mut self_type_rib = Rib::new(ItemRibKind);
 
@@ -4019,13 +4019,6 @@ impl<'a> Resolver<'a> {
                     this.resolve_type_parameter_bounds(item.id, bounds,
                                                        TraitDerivation);
 
-                    match *unbound {
-                        Some(ref tpb) => {
-                            this.resolve_trait_reference(item.id, tpb, TraitDerivation);
-                        }
-                        None => {}
-                    }
-
                     for trait_item in (*trait_items).iter() {
                         // Create a new rib for the trait_item-specific type
                         // parameters.
@@ -4273,12 +4266,6 @@ impl<'a> Resolver<'a> {
             self.resolve_type_parameter_bound(type_parameter.id, bound,
                                               TraitBoundingTypeParameter);
         }
-        match &type_parameter.unbound {
-            &Some(ref unbound) =>
-                self.resolve_trait_reference(
-                    type_parameter.id, unbound, TraitBoundingTypeParameter),
-            &None => {}
-        }
         match type_parameter.default {
             Some(ref ty) => self.resolve_type(&**ty),
             None => {}
@@ -4300,7 +4287,7 @@ impl<'a> Resolver<'a> {
                                     type_parameter_bound: &TyParamBound,
                                     reference_type: TraitReferenceType) {
         match *type_parameter_bound {
-            TraitTyParamBound(ref tref) => {
+            TraitTyParamBound(ref tref, _) => {
                 self.resolve_poly_trait_reference(id, tref, reference_type)
             }
             RegionTyParamBound(..) => {}

src/librustc_trans/save/mod.rs

@@ -710,7 +710,7 @@ impl <'l, 'tcx> DxrVisitor<'l, 'tcx> {
         // super-traits
         for super_bound in trait_refs.iter() {
             let trait_ref = match *super_bound {
-                ast::TraitTyParamBound(ref trait_ref) => {
+                ast::TraitTyParamBound(ref trait_ref, _) => {
                     trait_ref
                 }
                 ast::RegionTyParamBound(..) => {
@@ -1052,7 +1052,7 @@ impl<'l, 'tcx, 'v> Visitor<'v> for DxrVisitor<'l, 'tcx> {
                                   &**typ,
                                   impl_items)
             }
-            ast::ItemTrait(_, ref generics, _, ref trait_refs, ref methods) =>
+            ast::ItemTrait(_, ref generics, ref trait_refs, ref methods) =>
                 self.process_trait(item, generics, trait_refs, methods),
             ast::ItemMod(ref m) => self.process_mod(item, m),
             ast::ItemTy(ref ty, ref ty_params) => {
@@ -1076,7 +1076,7 @@ impl<'l, 'tcx, 'v> Visitor<'v> for DxrVisitor<'l, 'tcx> {
     fn visit_generics(&mut self, generics: &ast::Generics) {
         for param in generics.ty_params.iter() {
             for bound in param.bounds.iter() {
-                if let ast::TraitTyParamBound(ref trait_ref) = *bound {
+                if let ast::TraitTyParamBound(ref trait_ref, _) = *bound {
                     self.process_trait_ref(&trait_ref.trait_ref, None);
                 }
             }

src/librustc_typeck/astconv.rs

@@ -1625,7 +1625,7 @@ pub fn partition_bounds<'a>(tcx: &ty::ctxt,
     let mut trait_def_ids = DefIdMap::new();
     for ast_bound in ast_bounds.iter() {
         match *ast_bound {
-            ast::TraitTyParamBound(ref b) => {
+            ast::TraitTyParamBound(ref b, ast::TraitBoundModifier::None) => {
                 match ::lookup_def_tcx(tcx, b.trait_ref.path.span, b.trait_ref.ref_id) {
                     def::DefTrait(trait_did) => {
                         match trait_def_ids.get(&trait_did) {
@@ -1663,6 +1663,7 @@ pub fn partition_bounds<'a>(tcx: &ty::ctxt,
                 }
                 trait_bounds.push(b);
             }
+            ast::TraitTyParamBound(_, ast::TraitBoundModifier::Maybe) => {}
             ast::RegionTyParamBound(ref l) => {
                 region_bounds.push(l);
             }

src/librustc_typeck/check/mod.rs

@@ -658,7 +658,7 @@ pub fn check_item(ccx: &CrateCtxt, it: &ast::Item) {
         }
 
       }
-      ast::ItemTrait(_, _, _, _, ref trait_methods) => {
+      ast::ItemTrait(_, _, _, ref trait_methods) => {
         let trait_def = ty::lookup_trait_def(ccx.tcx, local_def(it.id));
         for trait_method in trait_methods.iter() {
             match *trait_method {

src/librustc_typeck/collect.rs

@@ -259,7 +259,7 @@ fn collect_trait_methods<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
                                    trait_def: &ty::TraitDef<'tcx>) {
     let tcx = ccx.tcx;
     if let ast_map::NodeItem(item) = tcx.map.get(trait_id) {
-        if let ast::ItemTrait(_, _, _, _, ref trait_items) = item.node {
+        if let ast::ItemTrait(_, _, _, ref trait_items) = item.node {
             // For each method, construct a suitable ty::Method and
             // store it into the `tcx.impl_or_trait_items` table:
             for trait_item in trait_items.iter() {
@@ -627,11 +627,6 @@ pub fn ensure_no_ty_param_bounds(ccx: &CrateCtxt,
                 ast::RegionTyParamBound(..) => { }
             }
         }
-
-        match ty_param.unbound {
-            Some(_) => { warn = true; }
-            None => { }
-        }
     }
 
     if warn {
@@ -1146,7 +1141,7 @@ pub fn convert(ccx: &CrateCtxt, it: &ast::Item) {
                                                AllowEqConstraints::DontAllow);
             }
         },
-        ast::ItemTrait(_, _, _, _, ref trait_methods) => {
+        ast::ItemTrait(_, _, _, ref trait_methods) => {
             let trait_def = trait_def_of_item(ccx, it);
 
             debug!("trait_def: ident={} trait_def={}",
@@ -1338,13 +1333,12 @@ pub fn trait_def_of_item<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
         return def.clone();
     }
 
-    let (unsafety, generics, unbound, bounds, items) = match it.node {
+    let (unsafety, generics, bounds, items) = match it.node {
         ast::ItemTrait(unsafety,
                        ref generics,
-                       ref unbound,
                        ref supertraits,
                        ref items) => {
-            (unsafety, generics, unbound, supertraits, items.as_slice())
+            (unsafety, generics, supertraits, items.as_slice())
         }
         ref s => {
             tcx.sess.span_bug(
@@ -1367,7 +1361,6 @@ pub fn trait_def_of_item<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
                                 token::SELF_KEYWORD_NAME,
                                 self_param_ty,
                                 bounds.as_slice(),
-                                unbound,
                                 it.span);
 
     let substs = mk_item_substs(ccx, &ty_generics);
@@ -1683,29 +1676,37 @@ fn ty_generics_for_fn_or_method<'tcx,AC>(
                 create_type_parameters_for_associated_types)
 }
 
-// Add the Sized bound, unless the type parameter is marked as `Sized?`.
+// Add the Sized bound, unless the type parameter is marked as `?Sized`.
 fn add_unsized_bound<'tcx,AC>(this: &AC,
-                              unbound: &Option<ast::TraitRef>,
                               bounds: &mut ty::BuiltinBounds,
-                              desc: &str,
+                              ast_bounds: &[ast::TyParamBound],
                               span: Span)
                               where AC: AstConv<'tcx> {
+    // Try to find an unbound in bounds.
+    let mut unbound = None;
+    for ab in ast_bounds.iter() {
+        if let &ast::TraitTyParamBound(ref ptr, ast::TraitBoundModifier::Maybe) = ab  {
+            if unbound.is_none() {
+                assert!(ptr.bound_lifetimes.is_empty());
+                unbound = Some(ptr.trait_ref.clone());
+            } else {
+                this.tcx().sess.span_err(span, "type parameter has more than one relaxed default \
+                                                bound, only one is supported");
+            }
+        }
+    }
+
     let kind_id = this.tcx().lang_items.require(SizedTraitLangItem);
     match unbound {
-        &Some(ref tpb) => {
+        Some(ref tpb) => {
             // FIXME(#8559) currently requires the unbound to be built-in.
             let trait_def_id = ty::trait_ref_to_def_id(this.tcx(), tpb);
             match kind_id {
                 Ok(kind_id) if trait_def_id != kind_id => {
                     this.tcx().sess.span_warn(span,
-                                              format!("default bound relaxed \
-                                                       for a {}, but this \
-                                                       does nothing because \
-                                                       the given bound is not \
-                                                       a default. \
-                                                       Only `Sized?` is \
-                                                       supported",
-                                                      desc)[]);
+                                              "default bound relaxed for a type parameter, but \
+                                               this does nothing because the given bound is not \
+                                               a default. Only `?Sized` is supported");
                     ty::try_add_builtin_trait(this.tcx(),
                                               kind_id,
                                               bounds);
@@ -1717,7 +1718,7 @@ fn add_unsized_bound<'tcx,AC>(this: &AC,
             ty::try_add_builtin_trait(this.tcx(), kind_id.unwrap(), bounds);
         }
         // No lang item for Sized, so we can't add it as a bound.
-        &None => {}
+        None => {}
     }
 }
 
@@ -1807,7 +1808,7 @@ fn ty_generics<'tcx,AC>(this: &AC,
 
                 for bound in bound_pred.bounds.iter() {
                     match bound {
-                        &ast::TyParamBound::TraitTyParamBound(ref poly_trait_ref) => {
+                        &ast::TyParamBound::TraitTyParamBound(ref poly_trait_ref, _) => {
                             let trait_ref = astconv::instantiate_poly_trait_ref(
                                 this,
                                 &ExplicitRscope,
@@ -1880,7 +1881,7 @@ fn ty_generics<'tcx,AC>(this: &AC,
             for bound in param.bounds.iter() {
                 // In the above example, `ast_trait_ref` is `Iterator`.
                 let ast_trait_ref = match *bound {
-                    ast::TraitTyParamBound(ref r) => r,
+                    ast::TraitTyParamBound(ref r, _) => r,
                     ast::RegionTyParamBound(..) => { continue; }
                 };
 
@@ -1978,7 +1979,6 @@ fn get_or_create_type_parameter_def<'tcx,AC>(this: &AC,
                                 param.ident.name,
                                 param_ty,
                                 param.bounds[],
-                                &param.unbound,
                                 param.span);
     let default = match param.default {
         None => None,
@@ -2023,7 +2023,6 @@ fn compute_bounds<'tcx,AC>(this: &AC,
                            name_of_bounded_thing: ast::Name,
                            param_ty: ty::ParamTy,
                            ast_bounds: &[ast::TyParamBound],
-                           unbound: &Option<ast::TraitRef>,
                            span: Span)
                            -> ty::ParamBounds<'tcx>
                            where AC: AstConv<'tcx> {
@@ -2032,11 +2031,9 @@ fn compute_bounds<'tcx,AC>(this: &AC,
                                              param_ty,
                                              ast_bounds);
 
-
     add_unsized_bound(this,
-                      unbound,
                       &mut param_bounds.builtin_bounds,
-                      "type parameter",
+                      ast_bounds,
                       span);
 
     check_bounds_compatible(this.tcx(),