Stop using Rc in TraitRef and TraitDef

The former stopped making sense when we started interning substs and made
TraitRef a 2-word copy type, and I'm moving the latter into an arena as
they live as long as the type context.

Author: Ariel Ben-Yehuda

src/librustc/metadata/csearch.rs

@@ -283,7 +283,7 @@ pub fn get_impl_polarity<'tcx>(tcx: &ty::ctxt<'tcx>,
 // if there is one.
 pub fn get_impl_trait<'tcx>(tcx: &ty::ctxt<'tcx>,
                             def: ast::DefId)
-                            -> Option<Rc<ty::TraitRef<'tcx>>> {
+                            -> Option<ty::TraitRef<'tcx>> {
     let cstore = &tcx.sess.cstore;
     let cdata = cstore.get_crate_data(def.krate);
     decoder::get_impl_trait(&*cdata, def.node, tcx)

src/librustc/metadata/decoder.rs

@@ -247,13 +247,13 @@ pub fn item_type<'tcx>(_item_id: ast::DefId, item: rbml::Doc,
 }
 
 fn doc_trait_ref<'tcx>(doc: rbml::Doc, tcx: &ty::ctxt<'tcx>, cdata: Cmd)
-                       -> Rc<ty::TraitRef<'tcx>> {
+                       -> ty::TraitRef<'tcx> {
     parse_trait_ref_data(doc.data, cdata.cnum, doc.start, tcx,
                          |_, did| translate_def_id(cdata, did))
 }
 
 fn item_trait_ref<'tcx>(doc: rbml::Doc, tcx: &ty::ctxt<'tcx>, cdata: Cmd)
-                        -> Rc<ty::TraitRef<'tcx>> {
+                        -> ty::TraitRef<'tcx> {
     let tp = reader::get_doc(doc, tag_item_trait_ref);
     doc_trait_ref(tp, tcx, cdata)
 }
@@ -490,7 +490,7 @@ pub fn get_impl_polarity<'tcx>(cdata: Cmd,
 pub fn get_impl_trait<'tcx>(cdata: Cmd,
                             id: ast::NodeId,
                             tcx: &ty::ctxt<'tcx>)
-                            -> Option<Rc<ty::TraitRef<'tcx>>>
+                            -> Option<ty::TraitRef<'tcx>>
 {
     let item_doc = lookup_item(id, cdata.data());
     let fam = item_family(item_doc);

src/librustc/metadata/encoder.rs

@@ -103,7 +103,7 @@ struct entry<T> {
 
 fn encode_trait_ref<'a, 'tcx>(rbml_w: &mut Encoder,
                               ecx: &EncodeContext<'a, 'tcx>,
-                              trait_ref: &ty::TraitRef<'tcx>,
+                              trait_ref: ty::TraitRef<'tcx>,
                               tag: usize) {
     let ty_str_ctxt = &tyencode::ctxt {
         diag: ecx.diag,
@@ -191,7 +191,7 @@ pub fn write_trait_ref<'a, 'tcx>(ecx: &EncodeContext<'a, 'tcx>,
         tcx: ecx.tcx,
         abbrevs: &ecx.type_abbrevs
     };
-    tyencode::enc_trait_ref(rbml_w, ty_str_ctxt, trait_ref);
+    tyencode::enc_trait_ref(rbml_w, ty_str_ctxt, *trait_ref);
 }
 
 pub fn write_region(ecx: &EncodeContext,
@@ -1201,7 +1201,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
           encode_unsafety(rbml_w, unsafety);
 
           let trait_ref = ty::impl_id_to_trait_ref(tcx, item.id);
-          encode_trait_ref(rbml_w, ecx, &*trait_ref, tag_item_trait_ref);
+          encode_trait_ref(rbml_w, ecx, trait_ref, tag_item_trait_ref);
           rbml_w.end_tag();
       }
       ast::ItemImpl(unsafety, polarity, _, ref opt_trait, ref ty, ref ast_items) => {
@@ -1246,7 +1246,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
         }
         if opt_trait.is_some() {
             let trait_ref = ty::impl_id_to_trait_ref(tcx, item.id);
-            encode_trait_ref(rbml_w, ecx, &*trait_ref, tag_item_trait_ref);
+            encode_trait_ref(rbml_w, ecx, trait_ref, tag_item_trait_ref);
         }
         encode_path(rbml_w, path.clone());
         encode_stability(rbml_w, stab);
@@ -1314,7 +1314,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
                         tag_item_generics);
         encode_predicates(rbml_w, ecx, &ty::lookup_super_predicates(tcx, def_id),
                           tag_item_super_predicates);
-        encode_trait_ref(rbml_w, ecx, &*trait_def.trait_ref, tag_item_trait_ref);
+        encode_trait_ref(rbml_w, ecx, trait_def.trait_ref, tag_item_trait_ref);
         encode_name(rbml_w, item.ident.name);
         encode_attributes(rbml_w, &item.attrs);
         encode_visibility(rbml_w, vis);

src/librustc/metadata/tydecode.rs

@@ -23,7 +23,6 @@ use middle::subst;
 use middle::subst::VecPerParamSpace;
 use middle::ty::{self, AsPredicate, Ty};
 
-use std::rc::Rc;
 use std::str;
 use syntax::abi;
 use syntax::ast;
@@ -182,7 +181,7 @@ pub fn parse_bare_fn_ty_data<'tcx, F>(data: &[u8], crate_num: ast::CrateNum, pos
 
 pub fn parse_trait_ref_data<'tcx, F>(data: &[u8], crate_num: ast::CrateNum, pos: usize,
                                      tcx: &ty::ctxt<'tcx>, conv: F)
-                                     -> Rc<ty::TraitRef<'tcx>> where
+                                     -> ty::TraitRef<'tcx> where
     F: FnMut(DefIdSource, ast::DefId) -> ast::DefId,
 {
     debug!("parse_trait_ref_data {}", data_log_string(data, pos));
@@ -434,19 +433,19 @@ fn parse_str(st: &mut PState, term: char) -> String {
 }
 
 fn parse_trait_ref<'a, 'tcx, F>(st: &mut PState<'a, 'tcx>, mut conv: F)
-                                -> Rc<ty::TraitRef<'tcx>> where
+                                -> ty::TraitRef<'tcx> where
     F: FnMut(DefIdSource, ast::DefId) -> ast::DefId,
 {
     parse_trait_ref_(st, &mut conv)
 }
 
 fn parse_trait_ref_<'a, 'tcx, F>(st: &mut PState<'a, 'tcx>, conv: &mut F)
-                              -> Rc<ty::TraitRef<'tcx>> where
+                              -> ty::TraitRef<'tcx> where
     F: FnMut(DefIdSource, ast::DefId) -> ast::DefId,
 {
     let def = parse_def_(st, NominalType, conv);
     let substs = st.tcx.mk_substs(parse_substs_(st, conv));
-    Rc::new(ty::TraitRef {def_id: def, substs: substs})
+    ty::TraitRef {def_id: def, substs: substs}
 }
 
 fn parse_ty<'a, 'tcx, F>(st: &mut PState<'a, 'tcx>, mut conv: F) -> Ty<'tcx> where

src/librustc/metadata/tyencode.rs

@@ -94,7 +94,7 @@ pub fn enc_ty<'a, 'tcx>(w: &mut Encoder, cx: &ctxt<'a, 'tcx>, t: Ty<'tcx>) {
         ty::ty_trait(box ty::TyTrait { ref principal,
                                        ref bounds }) => {
             mywrite!(w, "x[");
-            enc_trait_ref(w, cx, &*principal.0);
+            enc_trait_ref(w, cx, principal.0);
             enc_existential_bounds(w, cx, bounds);
             mywrite!(w, "]");
         }
@@ -149,7 +149,7 @@ pub fn enc_ty<'a, 'tcx>(w: &mut Encoder, cx: &ctxt<'a, 'tcx>, t: Ty<'tcx>) {
         }
         ty::ty_projection(ref data) => {
             mywrite!(w, "P[");
-            enc_trait_ref(w, cx, &*data.trait_ref);
+            enc_trait_ref(w, cx, data.trait_ref);
             mywrite!(w, "{}]", token::get_name(data.item_name));
         }
         ty::ty_err => {
@@ -309,7 +309,7 @@ fn enc_bound_region(w: &mut Encoder, cx: &ctxt, br: ty::BoundRegion) {
 }
 
 pub fn enc_trait_ref<'a, 'tcx>(w: &mut Encoder, cx: &ctxt<'a, 'tcx>,
-                               s: &ty::TraitRef<'tcx>) {
+                               s: ty::TraitRef<'tcx>) {
     mywrite!(w, "{}|", (cx.ds)(s.def_id));
     enc_substs(w, cx, s.substs);
 }
@@ -394,7 +394,7 @@ pub fn enc_bounds<'a, 'tcx>(w: &mut Encoder, cx: &ctxt<'a, 'tcx>,
 
     for tp in &bs.trait_bounds {
         mywrite!(w, "I");
-        enc_trait_ref(w, cx, &*tp.0);
+        enc_trait_ref(w, cx, tp.0);
     }
 
     for tp in &bs.projection_bounds {
@@ -446,7 +446,7 @@ pub fn enc_predicate<'a, 'tcx>(w: &mut Encoder,
     match *p {
         ty::Predicate::Trait(ref trait_ref) => {
             mywrite!(w, "t");
-            enc_trait_ref(w, cx, &*trait_ref.0.trait_ref);
+            enc_trait_ref(w, cx, trait_ref.0.trait_ref);
         }
         ty::Predicate::Equate(ty::Binder(ty::EquatePredicate(a, b))) => {
             mywrite!(w, "e");
@@ -473,7 +473,7 @@ pub fn enc_predicate<'a, 'tcx>(w: &mut Encoder,
 fn enc_projection_predicate<'a, 'tcx>(w: &mut Encoder,
                                       cx: &ctxt<'a, 'tcx>,
                                       data: &ty::ProjectionPredicate<'tcx>) {
-    enc_trait_ref(w, cx, &*data.projection_ty.trait_ref);
+    enc_trait_ref(w, cx, data.projection_ty.trait_ref);
     mywrite!(w, "{}|", token::get_name(data.projection_ty.item_name));
     enc_ty(w, cx, data.ty);
 }

src/librustc/middle/astencode.rs

@@ -41,7 +41,6 @@ use syntax;
 use std::cell::Cell;
 use std::io::SeekFrom;
 use std::io::prelude::*;
-use std::rc::Rc;
 use std::fmt::Debug;
 
 use rbml::reader;
@@ -890,7 +889,7 @@ impl<'a, 'tcx> rbml_writer_helpers<'tcx> for Encoder<'a> {
                     this.emit_enum_variant("MethodTypeParam", 2, 1, |this| {
                         this.emit_struct("MethodParam", 2, |this| {
                             try!(this.emit_struct_field("trait_ref", 0, |this| {
-                                Ok(this.emit_trait_ref(ecx, &*p.trait_ref))
+                                Ok(this.emit_trait_ref(ecx, &p.trait_ref))
                             }));
                             try!(this.emit_struct_field("method_num", 0, |this| {
                                 this.emit_uint(p.method_num)
@@ -914,7 +913,7 @@ impl<'a, 'tcx> rbml_writer_helpers<'tcx> for Encoder<'a> {
                     this.emit_enum_variant("MethodTraitObject", 3, 1, |this| {
                         this.emit_struct("MethodObject", 2, |this| {
                             try!(this.emit_struct_field("trait_ref", 0, |this| {
-                                Ok(this.emit_trait_ref(ecx, &*o.trait_ref))
+                                Ok(this.emit_trait_ref(ecx, &o.trait_ref))
                             }));
                             try!(this.emit_struct_field("object_trait_id", 0, |this| {
                                 Ok(this.emit_def_id(o.object_trait_id))
@@ -1208,7 +1207,7 @@ fn encode_side_tables_for_id(ecx: &e::EncodeContext,
     if let Some(trait_ref) = tcx.object_cast_map.borrow().get(&id) {
         rbml_w.tag(c::tag_table_object_cast_map, |rbml_w| {
             rbml_w.id(id);
-            rbml_w.emit_trait_ref(ecx, &*trait_ref.0);
+            rbml_w.emit_trait_ref(ecx, &trait_ref.0);
         })
     }
 
@@ -1275,7 +1274,7 @@ trait rbml_decoder_decoder_helpers<'tcx> {
     fn read_ty<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>) -> Ty<'tcx>;
     fn read_tys<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>) -> Vec<Ty<'tcx>>;
     fn read_trait_ref<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>)
-                              -> Rc<ty::TraitRef<'tcx>>;
+                              -> ty::TraitRef<'tcx>;
     fn read_poly_trait_ref<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>)
                                    -> ty::PolyTraitRef<'tcx>;
     fn read_type_param_def<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>)
@@ -1469,7 +1468,7 @@ impl<'a, 'tcx> rbml_decoder_decoder_helpers<'tcx> for reader::Decoder<'a> {
     }
 
     fn read_trait_ref<'b, 'c>(&mut self, dcx: &DecodeContext<'b, 'c, 'tcx>)
-                              -> Rc<ty::TraitRef<'tcx>> {
+                              -> ty::TraitRef<'tcx> {
         self.read_opaque(|this, doc| {
             let ty = tydecode::parse_trait_ref_data(
                 doc.data,

src/librustc/middle/const_eval.rs

@@ -942,8 +942,8 @@ fn resolve_trait_associated_const<'a, 'tcx: 'a>(tcx: &'a ty::ctxt<'tcx>,
     let trait_substs = tcx.mk_substs(trait_substs);
     debug!("resolve_trait_associated_const: trait_substs={}",
            trait_substs.repr(tcx));
-    let trait_ref = ty::Binder(Rc::new(ty::TraitRef { def_id: trait_id,
-                                                      substs: trait_substs }));
+    let trait_ref = ty::Binder(ty::TraitRef { def_id: trait_id,
+                                              substs: trait_substs });
 
     ty::populate_implementations_for_trait_if_necessary(tcx, trait_ref.def_id());
     let infcx = infer::new_infer_ctxt(tcx);

src/librustc/middle/implicator.rs

@@ -16,7 +16,6 @@ use middle::traits;
 use middle::ty::{self, RegionEscape, ToPolyTraitRef, Ty};
 use middle::ty_fold::{TypeFoldable, TypeFolder};
 
-use std::rc::Rc;
 use syntax::ast;
 use syntax::codemap::Span;
 
@@ -324,7 +323,7 @@ impl<'a, 'tcx> Implicator<'a, 'tcx> {
     }
 
     fn accumulate_from_assoc_types(&mut self,
-                                   trait_ref: Rc<ty::TraitRef<'tcx>>)
+                                   trait_ref: ty::TraitRef<'tcx>)
     {
         debug!("accumulate_from_assoc_types({})",
                trait_ref.repr(self.tcx()));
@@ -442,7 +441,7 @@ pub fn object_region_bounds<'tcx>(
     // Note that we preserve the overall binding levels here.
     assert!(!open_ty.has_escaping_regions());
     let substs = tcx.mk_substs(principal.0.substs.with_self_ty(open_ty));
-    let trait_refs = vec!(ty::Binder(Rc::new(ty::TraitRef::new(principal.0.def_id, substs))));
+    let trait_refs = vec!(ty::Binder(ty::TraitRef::new(principal.0.def_id, substs)));
 
     let param_bounds = ty::ParamBounds {
         region_bounds: Vec::new(),

src/librustc/middle/infer/error_reporting.rs

@@ -79,7 +79,6 @@ use middle::ty::{self, Ty};
 use middle::ty::{Region, ReFree};
 use std::cell::{Cell, RefCell};
 use std::char::from_u32;
-use std::rc::Rc;
 use std::string::String;
 use syntax::ast;
 use syntax::ast_map;
@@ -1680,13 +1679,13 @@ impl<'tcx> Resolvable<'tcx> for Ty<'tcx> {
     }
 }
 
-impl<'tcx> Resolvable<'tcx> for Rc<ty::TraitRef<'tcx>> {
+impl<'tcx> Resolvable<'tcx> for ty::TraitRef<'tcx> {
     fn resolve<'a>(&self, infcx: &InferCtxt<'a, 'tcx>)
-                   -> Rc<ty::TraitRef<'tcx>> {
-        Rc::new(infcx.resolve_type_vars_if_possible(&**self))
+                   -> ty::TraitRef<'tcx> {
+        infcx.resolve_type_vars_if_possible(self)
     }
     fn contains_error(&self) -> bool {
-        ty::trait_ref_contains_error(&**self)
+        ty::trait_ref_contains_error(self)
     }
 }
 
@@ -1699,7 +1698,7 @@ impl<'tcx> Resolvable<'tcx> for ty::PolyTraitRef<'tcx> {
     }
 
     fn contains_error(&self) -> bool {
-        ty::trait_ref_contains_error(&*self.0)
+        ty::trait_ref_contains_error(&self.0)
     }
 }
 

src/librustc/middle/infer/mod.rs

@@ -33,7 +33,6 @@ use middle::ty_relate::{Relate, RelateResult, TypeRelation};
 use rustc_data_structures::unify::{self, UnificationTable};
 use std::cell::{RefCell};
 use std::fmt;
-use std::rc::Rc;
 use syntax::ast;
 use syntax::codemap;
 use syntax::codemap::Span;
@@ -155,7 +154,7 @@ impl fmt::Display for TypeOrigin {
 #[derive(Clone, Debug)]
 pub enum ValuePairs<'tcx> {
     Types(ty::expected_found<Ty<'tcx>>),
-    TraitRefs(ty::expected_found<Rc<ty::TraitRef<'tcx>>>),
+    TraitRefs(ty::expected_found<ty::TraitRef<'tcx>>),
     PolyTraitRefs(ty::expected_found<ty::PolyTraitRef<'tcx>>),
 }
 
@@ -663,8 +662,8 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
     pub fn sub_trait_refs(&self,
                           a_is_expected: bool,
                           origin: TypeOrigin,
-                          a: Rc<ty::TraitRef<'tcx>>,
-                          b: Rc<ty::TraitRef<'tcx>>)
+                          a: ty::TraitRef<'tcx>,
+                          b: ty::TraitRef<'tcx>)
                           -> UnitResult<'tcx>
     {
         debug!("sub_trait_refs({} <: {})",
@@ -675,7 +674,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                 origin: origin,
                 values: TraitRefs(expected_found(a_is_expected, a.clone(), b.clone()))
             };
-            self.sub(a_is_expected, trace).relate(&*a, &*b).map(|_| ())
+            self.sub(a_is_expected, trace).relate(&a, &b).map(|_| ())
         })
     }
 
@@ -873,8 +872,8 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         format!("({})", tstrs.connect(", "))
     }
 
-    pub fn trait_ref_to_string(&self, t: &Rc<ty::TraitRef<'tcx>>) -> String {
-        let t = self.resolve_type_vars_if_possible(&**t);
+    pub fn trait_ref_to_string(&self, t: &ty::TraitRef<'tcx>) -> String {
+        let t = self.resolve_type_vars_if_possible(t);
         t.user_string(self.tcx)
     }
 

src/librustc/middle/traits/coherence.rs

@@ -20,7 +20,6 @@ use super::util;
 use middle::subst::{Subst, Substs, TypeSpace};
 use middle::ty::{self, ToPolyTraitRef, Ty};
 use middle::infer::{self, InferCtxt};
-use std::rc::Rc;
 use syntax::ast;
 use syntax::codemap::{DUMMY_SP, Span};
 use util::ppaux::Repr;
@@ -139,7 +138,7 @@ type SubstsFn = for<'a,'tcx> fn(infcx: &InferCtxt<'a, 'tcx>,
 fn impl_trait_ref_and_oblig<'a,'tcx>(selcx: &mut SelectionContext<'a,'tcx>,
                                      impl_def_id: ast::DefId,
                                      substs_fn: SubstsFn)
-                                     -> (Rc<ty::TraitRef<'tcx>>,
+                                     -> (ty::TraitRef<'tcx>,
                                          Vec<PredicateObligation<'tcx>>)
 {
     let impl_substs =
@@ -341,5 +340,3 @@ fn ty_is_local_constructor<'tcx>(tcx: &ty::ctxt<'tcx>,
         }
     }
 }
-
-

src/librustc/middle/traits/error_reporting.rs

@@ -191,7 +191,7 @@ pub fn report_selection_error<'a, 'tcx>(infcx: &InferCtxt<'a, 'tcx>,
                                         trait_ref.self_ty().user_string(infcx.tcx));
                                 // Check if it has a custom "#[rustc_on_unimplemented]"
                                 // error message, report with that message if it does
-                                let custom_note = report_on_unimplemented(infcx, &*trait_ref.0,
+                                let custom_note = report_on_unimplemented(infcx, &trait_ref.0,
                                                                           obligation.cause.span);
                                 if let Some(s) = custom_note {
                                     infcx.tcx.sess.span_note(obligation.cause.span,