Centralize on using Binder to introduce new binding levels, rather than having FnSig carry an implicit binding level. This means that we be more typesafe in general, since things that instantiate bound regions can drop the Binder to reflect that.

Author: nikomatsakis

src/librustc/metadata/decoder.rs

@@ -429,7 +429,7 @@ pub fn get_impl_trait<'tcx>(cdata: Cmd,
 {
     let item_doc = lookup_item(id, cdata.data());
     reader::maybe_get_doc(item_doc, tag_item_trait_ref).map(|tp| {
-        Rc::new(ty::bind(doc_trait_ref(tp, tcx, cdata)))
+        Rc::new(ty::Binder(doc_trait_ref(tp, tcx, cdata)))
     })
 }
 
@@ -704,7 +704,7 @@ pub fn get_enum_variants<'tcx>(intr: Rc<IdentInterner>, cdata: Cmd, id: ast::Nod
         let name = item_name(&*intr, item);
         let (ctor_ty, arg_tys, arg_names) = match ctor_ty.sty {
             ty::ty_bare_fn(ref f) =>
-                (Some(ctor_ty), f.sig.inputs.clone(), None),
+                (Some(ctor_ty), f.sig.0.inputs.clone(), None),
             _ => { // Nullary or struct enum variant.
                 let mut arg_names = Vec::new();
                 let arg_tys = get_struct_fields(intr.clone(), cdata, did.node)

src/librustc/metadata/tydecode.rs

@@ -414,7 +414,7 @@ fn parse_ty<'a, 'tcx>(st: &mut PState<'a, 'tcx>, conv: conv_did) -> Ty<'tcx> {
       }
       'x' => {
         assert_eq!(next(st), '[');
-        let trait_ref = ty::bind(parse_trait_ref(st, |x,y| conv(x,y)));
+        let trait_ref = ty::Binder(parse_trait_ref(st, |x,y| conv(x,y)));
         let bounds = parse_existential_bounds(st, |x,y| conv(x,y));
         assert_eq!(next(st), ']');
         return ty::mk_trait(st.tcx, trait_ref, bounds);
@@ -603,7 +603,7 @@ fn parse_bare_fn_ty<'a, 'tcx>(st: &mut PState<'a, 'tcx>,
     }
 }
 
-fn parse_sig<'a, 'tcx>(st: &mut PState<'a, 'tcx>, conv: conv_did) -> ty::FnSig<'tcx> {
+fn parse_sig<'a, 'tcx>(st: &mut PState<'a, 'tcx>, conv: conv_did) -> ty::PolyFnSig<'tcx> {
     assert_eq!(next(st), '[');
     let mut inputs = Vec::new();
     while peek(st) != ']' {
@@ -622,9 +622,9 @@ fn parse_sig<'a, 'tcx>(st: &mut PState<'a, 'tcx>, conv: conv_did) -> ty::FnSig<'
         }
         _ => ty::FnConverging(parse_ty(st, |x,y| conv(x,y)))
     };
-    ty::FnSig {inputs: inputs,
-               output: output,
-               variadic: variadic}
+    ty::Binder(ty::FnSig {inputs: inputs,
+                        output: output,
+                        variadic: variadic})
 }
 
 // Rust metadata parsing
@@ -669,7 +669,7 @@ pub fn parse_predicate<'a,'tcx>(st: &mut PState<'a, 'tcx>,
                                 -> ty::Predicate<'tcx>
 {
     match next(st) {
-        't' => ty::Predicate::Trait(Rc::new(ty::bind(parse_trait_ref(st, conv)))),
+        't' => ty::Predicate::Trait(Rc::new(ty::Binder(parse_trait_ref(st, conv)))),
         'e' => ty::Predicate::Equate(parse_ty(st, |x,y| conv(x,y)),
                                      parse_ty(st, |x,y| conv(x,y))),
         'r' => ty::Predicate::RegionOutlives(parse_region(st, |x,y| conv(x,y)),
@@ -764,7 +764,7 @@ fn parse_bounds<'a, 'tcx>(st: &mut PState<'a, 'tcx>, conv: conv_did)
             }
             'I' => {
                 param_bounds.trait_bounds.push(
-                    Rc::new(ty::bind(parse_trait_ref(st, |x,y| conv(x,y)))));
+                    Rc::new(ty::Binder(parse_trait_ref(st, |x,y| conv(x,y)))));
             }
             '.' => {
                 return param_bounds;

src/librustc/metadata/tyencode.rs

@@ -251,7 +251,7 @@ fn enc_sty<'a, 'tcx>(w: &mut SeekableMemWriter, cx: &ctxt<'a, 'tcx>,
         ty::ty_trait(box ty::TyTrait { ref principal,
                                        ref bounds }) => {
             mywrite!(w, "x[");
-            enc_trait_ref(w, cx, &principal.value);
+            enc_trait_ref(w, cx, &principal.0);
             enc_existential_bounds(w, cx, bounds);
             mywrite!(w, "]");
         }
@@ -351,18 +351,18 @@ pub fn enc_closure_ty<'a, 'tcx>(w: &mut SeekableMemWriter, cx: &ctxt<'a, 'tcx>,
 }
 
 fn enc_fn_sig<'a, 'tcx>(w: &mut SeekableMemWriter, cx: &ctxt<'a, 'tcx>,
-                        fsig: &ty::FnSig<'tcx>) {
+                        fsig: &ty::PolyFnSig<'tcx>) {
     mywrite!(w, "[");
-    for ty in fsig.inputs.iter() {
+    for ty in fsig.0.inputs.iter() {
         enc_ty(w, cx, *ty);
     }
     mywrite!(w, "]");
-    if fsig.variadic {
+    if fsig.0.variadic {
         mywrite!(w, "V");
     } else {
         mywrite!(w, "N");
     }
-    match fsig.output {
+    match fsig.0.output {
         ty::FnConverging(result_type) => {
             enc_ty(w, cx, result_type);
         }
@@ -401,7 +401,7 @@ pub fn enc_bounds<'a, 'tcx>(w: &mut SeekableMemWriter, cx: &ctxt<'a, 'tcx>,
 
     for tp in bs.trait_bounds.iter() {
         mywrite!(w, "I");
-        enc_trait_ref(w, cx, &tp.value);
+        enc_trait_ref(w, cx, &tp.0);
     }
 
     mywrite!(w, ".");
@@ -425,7 +425,7 @@ pub fn enc_predicate<'a, 'tcx>(w: &mut SeekableMemWriter,
     match *p {
         ty::Predicate::Trait(ref trait_ref) => {
             mywrite!(w, "t");
-            enc_trait_ref(w, cx, &trait_ref.value);
+            enc_trait_ref(w, cx, &trait_ref.0);
         }
         ty::Predicate::Equate(a, b) => {
             mywrite!(w, "e");

src/librustc/middle/astencode.rs

@@ -887,7 +887,7 @@ 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.value))
+                                Ok(this.emit_trait_ref(ecx, &p.trait_ref.0))
                             }));
                             try!(this.emit_struct_field("method_num", 0, |this| {
                                 this.emit_uint(p.method_num)
@@ -901,7 +901,7 @@ 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.value))
+                                Ok(this.emit_trait_ref(ecx, &o.trait_ref.0))
                             }));
                             try!(this.emit_struct_field("object_trait_id", 0, |this| {
                                 Ok(this.emit_def_id(o.object_trait_id))
@@ -1113,7 +1113,7 @@ impl<'a, 'tcx> rbml_writer_helpers<'tcx> for Encoder<'a> {
                     this.emit_enum_variant("UnsizeVtable", 2, 4, |this| {
                         this.emit_enum_variant_arg(0, |this| {
                             try!(this.emit_struct_field("principal", 0, |this| {
-                                Ok(this.emit_trait_ref(ecx, &principal.value))
+                                Ok(this.emit_trait_ref(ecx, &principal.0))
                             }));
                             this.emit_struct_field("bounds", 1, |this| {
                                 Ok(this.emit_existential_bounds(ecx, b))
@@ -1277,7 +1277,7 @@ fn encode_side_tables_for_id(ecx: &e::EncodeContext,
         rbml_w.tag(c::tag_table_object_cast_map, |rbml_w| {
             rbml_w.id(id);
             rbml_w.tag(c::tag_table_val, |rbml_w| {
-                rbml_w.emit_trait_ref(ecx, &trait_ref.value);
+                rbml_w.emit_trait_ref(ecx, &trait_ref.0);
             })
         })
     }
@@ -1552,7 +1552,7 @@ impl<'a, 'tcx> rbml_decoder_decoder_helpers<'tcx> for reader::Decoder<'a> {
 
     fn read_poly_trait_ref<'b, 'c>(&mut self, dcx: &DecodeContext<'b, 'c, 'tcx>)
                                    -> Rc<ty::PolyTraitRef<'tcx>> {
-        Rc::new(ty::bind(self.read_opaque(|this, doc| {
+        Rc::new(ty::Binder(self.read_opaque(|this, doc| {
             let ty = tydecode::parse_trait_ref_data(
                 doc.data,
                 dcx.cdata.cnum,

src/librustc/middle/expr_use_visitor.rs

@@ -265,7 +265,7 @@ impl OverloadedCallType {
             }
             Some(ref trait_ref) => (*trait_ref).clone(),
         };
-        OverloadedCallType::from_trait_id(tcx, trait_ref.value.def_id)
+        OverloadedCallType::from_trait_id(tcx, trait_ref.def_id())
     }
 
     fn from_unboxed_closure(tcx: &ty::ctxt, closure_did: ast::DefId)

src/librustc/middle/fast_reject.rs

@@ -60,7 +60,7 @@ pub fn simplify_type(tcx: &ty::ctxt,
         ty::ty_vec(..) => Some(VecSimplifiedType),
         ty::ty_ptr(_) => Some(PtrSimplifiedType),
         ty::ty_trait(ref trait_info) => {
-            Some(TraitSimplifiedType(trait_info.principal.value.def_id))
+            Some(TraitSimplifiedType(trait_info.principal.def_id()))
         }
         ty::ty_struct(def_id, _) => {
             Some(StructSimplifiedType(def_id))
@@ -83,10 +83,10 @@ pub fn simplify_type(tcx: &ty::ctxt,
             Some(TupleSimplifiedType(tys.len()))
         }
         ty::ty_closure(ref f) => {
-            Some(FunctionSimplifiedType(f.sig.inputs.len()))
+            Some(FunctionSimplifiedType(f.sig.0.inputs.len()))
         }
         ty::ty_bare_fn(ref f) => {
-            Some(FunctionSimplifiedType(f.sig.inputs.len()))
+            Some(FunctionSimplifiedType(f.sig.0.inputs.len()))
         }
         ty::ty_param(_) => {
             if can_simplify_params {

src/librustc/middle/infer/combine.rs

@@ -195,7 +195,7 @@ pub trait Combine<'tcx> {
                    b: &ty::BareFnTy<'tcx>) -> cres<'tcx, ty::BareFnTy<'tcx>> {
         let unsafety = try!(self.unsafeties(a.unsafety, b.unsafety));
         let abi = try!(self.abi(a.abi, b.abi));
-        let sig = try!(self.fn_sigs(&a.sig, &b.sig));
+        let sig = try!(self.binders(&a.sig, &b.sig));
         Ok(ty::BareFnTy {unsafety: unsafety,
                          abi: abi,
                          sig: sig})
@@ -222,7 +222,7 @@ pub trait Combine<'tcx> {
         let unsafety = try!(self.unsafeties(a.unsafety, b.unsafety));
         let onceness = try!(self.oncenesses(a.onceness, b.onceness));
         let bounds = try!(self.existential_bounds(a.bounds, b.bounds));
-        let sig = try!(self.fn_sigs(&a.sig, &b.sig));
+        let sig = try!(self.binders(&a.sig, &b.sig));
         let abi = try!(self.abi(a.abi, b.abi));
         Ok(ty::ClosureTy {
             unsafety: unsafety,
@@ -234,7 +234,43 @@ pub trait Combine<'tcx> {
         })
     }
 
-    fn fn_sigs(&self, a: &ty::FnSig<'tcx>, b: &ty::FnSig<'tcx>) -> cres<'tcx, ty::FnSig<'tcx>>;
+    fn fn_sigs(&self, a: &ty::FnSig<'tcx>, b: &ty::FnSig<'tcx>) -> cres<'tcx, ty::FnSig<'tcx>> {
+        if a.variadic != b.variadic {
+            return Err(ty::terr_variadic_mismatch(expected_found(self, a.variadic, b.variadic)));
+        }
+
+        let inputs = try!(argvecs(self,
+                                  a.inputs.as_slice(),
+                                  b.inputs.as_slice()));
+
+        let output = try!(match (a.output, b.output) {
+            (ty::FnConverging(a_ty), ty::FnConverging(b_ty)) =>
+                Ok(ty::FnConverging(try!(self.tys(a_ty, b_ty)))),
+            (ty::FnDiverging, ty::FnDiverging) =>
+                Ok(ty::FnDiverging),
+            (a, b) =>
+                Err(ty::terr_convergence_mismatch(
+                    expected_found(self, a != ty::FnDiverging, b != ty::FnDiverging))),
+        });
+
+        return Ok(ty::FnSig {inputs: inputs,
+                             output: output,
+                             variadic: a.variadic});
+
+
+        fn argvecs<'tcx, C: Combine<'tcx>>(combiner: &C,
+                                           a_args: &[Ty<'tcx>],
+                                           b_args: &[Ty<'tcx>])
+                                           -> cres<'tcx, Vec<Ty<'tcx>>>
+        {
+            if a_args.len() == b_args.len() {
+                a_args.iter().zip(b_args.iter())
+                    .map(|(a, b)| combiner.args(*a, *b)).collect()
+            } else {
+                Err(ty::terr_arg_count)
+            }
+        }
+    }
 
     fn args(&self, a: Ty<'tcx>, b: Ty<'tcx>) -> cres<'tcx, Ty<'tcx>> {
         self.contratys(a, b).and_then(|t| Ok(t))
@@ -312,14 +348,36 @@ pub trait Combine<'tcx> {
         }
     }
 
-    fn poly_trait_refs(&self,
-                       a: &ty::PolyTraitRef<'tcx>,
-                       b: &ty::PolyTraitRef<'tcx>)
-                       -> cres<'tcx, ty::PolyTraitRef<'tcx>>;
+    fn binders<T>(&self, a: &ty::Binder<T>, b: &ty::Binder<T>) -> cres<'tcx, ty::Binder<T>>
+        where T : Combineable<'tcx>;
     // this must be overridden to do correctly, so as to account for higher-ranked
     // behavior
 }
 
+pub trait Combineable<'tcx> : Repr<'tcx> + TypeFoldable<'tcx> {
+    fn combine<C:Combine<'tcx>>(combiner: &C, a: &Self, b: &Self) -> cres<'tcx, Self>;
+}
+
+impl<'tcx> Combineable<'tcx> for ty::TraitRef<'tcx> {
+    fn combine<C:Combine<'tcx>>(combiner: &C,
+                                a: &ty::TraitRef<'tcx>,
+                                b: &ty::TraitRef<'tcx>)
+                                -> cres<'tcx, ty::TraitRef<'tcx>>
+    {
+        combiner.trait_refs(a, b)
+    }
+}
+
+impl<'tcx> Combineable<'tcx> for ty::FnSig<'tcx> {
+    fn combine<C:Combine<'tcx>>(combiner: &C,
+                                a: &ty::FnSig<'tcx>,
+                                b: &ty::FnSig<'tcx>)
+                                -> cres<'tcx, ty::FnSig<'tcx>>
+    {
+        combiner.fn_sigs(a, b)
+    }
+}
+
 #[deriving(Clone)]
 pub struct CombineFields<'a, 'tcx: 'a> {
     pub infcx: &'a InferCtxt<'a, 'tcx>,
@@ -424,7 +482,7 @@ pub fn super_tys<'tcx, C: Combine<'tcx>>(this: &C,
       (&ty::ty_trait(ref a_),
        &ty::ty_trait(ref b_)) => {
           debug!("Trying to match traits {} and {}", a, b);
-          let principal = try!(this.poly_trait_refs(&a_.principal, &b_.principal));
+          let principal = try!(this.binders(&a_.principal, &b_.principal));
           let bounds = try!(this.existential_bounds(a_.bounds, b_.bounds));
           Ok(ty::mk_trait(tcx, principal, bounds))
       }

src/librustc/middle/infer/equate.rs

@@ -133,17 +133,10 @@ impl<'f, 'tcx> Combine<'tcx> for Equate<'f, 'tcx> {
         }
     }
 
-    fn fn_sigs(&self, a: &ty::FnSig<'tcx>, b: &ty::FnSig<'tcx>)
-               -> cres<'tcx, ty::FnSig<'tcx>>
+    fn binders<T>(&self, a: &ty::Binder<T>, b: &ty::Binder<T>) -> cres<'tcx, ty::Binder<T>>
+        where T : Combineable<'tcx>
     {
-        try!(self.sub().fn_sigs(a, b));
-        self.sub().fn_sigs(b, a)
-    }
-
-    fn poly_trait_refs(&self, a: &ty::PolyTraitRef<'tcx>, b: &ty::PolyTraitRef<'tcx>)
-                       -> cres<'tcx, ty::PolyTraitRef<'tcx>>
-    {
-        try!(self.sub().poly_trait_refs(a, b));
-        self.sub().poly_trait_refs(b, a)
+        try!(self.sub().binders(a, b));
+        self.sub().binders(b, a)
     }
 }

src/librustc/middle/infer/error_reporting.rs

@@ -1653,7 +1653,7 @@ impl<'tcx> Resolvable<'tcx> for Rc<ty::PolyTraitRef<'tcx>> {
         Rc::new(infcx.resolve_type_vars_if_possible(&**self))
     }
     fn contains_error(&self) -> bool {
-        ty::trait_ref_contains_error(&self.value)
+        ty::trait_ref_contains_error(&self.0)
     }
 }
 

src/librustc/middle/infer/glb.rs

@@ -121,13 +121,9 @@ impl<'f, 'tcx> Combine<'tcx> for Glb<'f, 'tcx> {
         super_lattice_tys(self, a, b)
     }
 
-    fn fn_sigs(&self, a: &ty::FnSig<'tcx>, b: &ty::FnSig<'tcx>)
-               -> cres<'tcx, ty::FnSig<'tcx>> {
-        self.higher_ranked_glb(a, b)
-    }
-
-    fn poly_trait_refs(&self, a: &ty::PolyTraitRef<'tcx>, b: &ty::PolyTraitRef<'tcx>)
-                       -> cres<'tcx, ty::PolyTraitRef<'tcx>> {
+    fn binders<T>(&self, a: &ty::Binder<T>, b: &ty::Binder<T>) -> cres<'tcx, ty::Binder<T>>
+        where T : Combineable<'tcx>
+    {
         self.higher_ranked_glb(a, b)
     }
 }