Auto merge of #22182 - nikomatsakis:cycles-in-collect, r=nikomatsakis

This resolves a number of bugs that trigger stack overflows or other cyclic errors.

r? @nick29581 (it is based on work that you started)
f? @jroesch (also based on your branch)

src/librustc/metadata/csearch.rs

@@ -233,6 +233,14 @@ pub fn get_trait_def<'tcx>(tcx: &ty::ctxt<'tcx>, def: ast::DefId) -> ty::TraitDe
     decoder::get_trait_def(&*cdata, def.node, tcx)
 }
 
+pub fn get_predicates<'tcx>(tcx: &ty::ctxt<'tcx>, def: ast::DefId)
+                            -> ty::GenericPredicates<'tcx>
+{
+    let cstore = &tcx.sess.cstore;
+    let cdata = cstore.get_crate_data(def.krate);
+    decoder::get_predicates(&*cdata, def.node, tcx)
+}
+
 pub fn get_field_type<'tcx>(tcx: &ty::ctxt<'tcx>, class_id: ast::DefId,
                             def: ast::DefId) -> ty::TypeScheme<'tcx> {
     let cstore = &tcx.sess.cstore;

src/librustc/metadata/decoder.rs

@@ -417,16 +417,22 @@ pub fn get_trait_def<'tcx>(cdata: Cmd,
     }
 }
 
-pub fn get_type<'tcx>(cdata: Cmd, id: ast::NodeId, tcx: &ty::ctxt<'tcx>)
-    -> ty::TypeScheme<'tcx> {
-
-    let item = lookup_item(id, cdata.data());
+pub fn get_predicates<'tcx>(cdata: Cmd,
+                            item_id: ast::NodeId,
+                            tcx: &ty::ctxt<'tcx>)
+                            -> ty::GenericPredicates<'tcx>
+{
+    let item_doc = lookup_item(item_id, cdata.data());
+    doc_predicates(item_doc, tcx, cdata, tag_item_generics)
+}
 
-    let t = item_type(ast::DefId { krate: cdata.cnum, node: id }, item, tcx,
+pub fn get_type<'tcx>(cdata: Cmd, id: ast::NodeId, tcx: &ty::ctxt<'tcx>)
+                      -> ty::TypeScheme<'tcx>
+{
+    let item_doc = lookup_item(id, cdata.data());
+    let t = item_type(ast::DefId { krate: cdata.cnum, node: id }, item_doc, tcx,
                       cdata);
-
-    let generics = doc_generics(item, tcx, cdata, tag_item_generics);
-
+    let generics = doc_generics(item_doc, tcx, cdata, tag_item_generics);
     ty::TypeScheme {
         generics: generics,
         ty: t
@@ -882,14 +888,15 @@ pub fn get_impl_or_trait_item<'tcx>(intr: Rc<IdentInterner>,
 
     match item_sort(method_doc) {
         'r' | 'p' => {
-            let generics = doc_generics(method_doc, tcx, cdata,
-                                        tag_method_ty_generics);
+            let generics = doc_generics(method_doc, tcx, cdata, tag_method_ty_generics);
+            let predicates = doc_predicates(method_doc, tcx, cdata, tag_method_ty_generics);
             let fty = doc_method_fty(method_doc, tcx, cdata);
             let explicit_self = get_explicit_self(method_doc);
             let provided_source = get_provided_source(method_doc, cdata);
 
             ty::MethodTraitItem(Rc::new(ty::Method::new(name,
                                                         generics,
+                                                        predicates,
                                                         fty,
                                                         explicit_self,
                                                         vis,
@@ -1520,6 +1527,17 @@ fn doc_generics<'tcx>(base_doc: rbml::Doc,
         true
     });
 
+    ty::Generics { types: types, regions: regions }
+}
+
+fn doc_predicates<'tcx>(base_doc: rbml::Doc,
+                        tcx: &ty::ctxt<'tcx>,
+                        cdata: Cmd,
+                        tag: uint)
+                        -> ty::GenericPredicates<'tcx>
+{
+    let doc = reader::get_doc(base_doc, tag);
+
     let mut predicates = subst::VecPerParamSpace::empty();
     reader::tagged_docs(doc, tag_predicate, |predicate_doc| {
         let space_doc = reader::get_doc(predicate_doc, tag_predicate_space);
@@ -1533,7 +1551,7 @@ fn doc_generics<'tcx>(base_doc: rbml::Doc,
         true
     });
 
-    ty::Generics { types: types, regions: regions, predicates: predicates }
+    ty::GenericPredicates { predicates: predicates }
 }
 
 pub fn is_associated_type(cdata: Cmd, id: ast::NodeId) -> bool {

src/librustc/metadata/encoder.rs

@@ -139,11 +139,21 @@ fn encode_item_variances(rbml_w: &mut Encoder,
     rbml_w.end_tag();
 }
 
+fn encode_bounds_and_type_for_item<'a, 'tcx>(rbml_w: &mut Encoder,
+                                             ecx: &EncodeContext<'a, 'tcx>,
+                                             id: ast::NodeId) {
+    encode_bounds_and_type(rbml_w,
+                           ecx,
+                           &ty::lookup_item_type(ecx.tcx, local_def(id)),
+                           &ty::lookup_predicates(ecx.tcx, local_def(id)));
+}
+
 fn encode_bounds_and_type<'a, 'tcx>(rbml_w: &mut Encoder,
                                     ecx: &EncodeContext<'a, 'tcx>,
-                                    pty: &ty::TypeScheme<'tcx>) {
-    encode_generics(rbml_w, ecx, &pty.generics, tag_item_generics);
-    encode_type(ecx, rbml_w, pty.ty);
+                                    scheme: &ty::TypeScheme<'tcx>,
+                                    predicates: &ty::GenericPredicates<'tcx>) {
+    encode_generics(rbml_w, ecx, &scheme.generics, &predicates, tag_item_generics);
+    encode_type(ecx, rbml_w, scheme.ty);
 }
 
 fn encode_variant_id(rbml_w: &mut Encoder, vid: DefId) {
@@ -353,8 +363,7 @@ fn encode_enum_variant_info(ecx: &EncodeContext,
             encode_disr_val(ecx, rbml_w, (*vi)[i].disr_val);
             disr_val = (*vi)[i].disr_val;
         }
-        encode_bounds_and_type(rbml_w, ecx,
-                               &lookup_item_type(ecx.tcx, def_id));
+        encode_bounds_and_type_for_item(rbml_w, ecx, def_id.local_id());
 
         ecx.tcx.map.with_path(variant.node.id, |path| encode_path(rbml_w, path));
         rbml_w.end_tag();
@@ -698,8 +707,7 @@ fn encode_info_for_struct(ecx: &EncodeContext,
                token::get_name(nm), id);
         encode_struct_field_family(rbml_w, field.vis);
         encode_name(rbml_w, nm);
-        encode_bounds_and_type(rbml_w, ecx,
-                               &lookup_item_type(ecx.tcx, local_def(id)));
+        encode_bounds_and_type_for_item(rbml_w, ecx, id);
         encode_def_id(rbml_w, local_def(id));
 
         let stab = stability::lookup(ecx.tcx, field.id);
@@ -724,8 +732,7 @@ fn encode_info_for_struct_ctor(ecx: &EncodeContext,
     rbml_w.start_tag(tag_items_data_item);
     encode_def_id(rbml_w, local_def(ctor_id));
     encode_family(rbml_w, 'o');
-    encode_bounds_and_type(rbml_w, ecx,
-                           &lookup_item_type(ecx.tcx, local_def(ctor_id)));
+    encode_bounds_and_type_for_item(rbml_w, ecx, ctor_id);
     encode_name(rbml_w, name.name);
     ecx.tcx.map.with_path(ctor_id, |path| encode_path(rbml_w, path));
     encode_parent_item(rbml_w, local_def(struct_id));
@@ -749,6 +756,7 @@ fn encode_info_for_struct_ctor(ecx: &EncodeContext,
 fn encode_generics<'a, 'tcx>(rbml_w: &mut Encoder,
                              ecx: &EncodeContext<'a, 'tcx>,
                              generics: &ty::Generics<'tcx>,
+                             predicates: &ty::GenericPredicates<'tcx>,
                              tag: uint)
 {
     rbml_w.start_tag(tag);
@@ -790,7 +798,7 @@ fn encode_generics<'a, 'tcx>(rbml_w: &mut Encoder,
         rbml_w.end_tag();
     }
 
-    for (space, _, predicate) in generics.predicates.iter_enumerated() {
+    for (space, _, predicate) in predicates.predicates.iter_enumerated() {
         rbml_w.start_tag(tag_predicate);
 
         rbml_w.wr_tagged_u8(tag_predicate_space, space as u8);
@@ -810,7 +818,7 @@ fn encode_method_ty_fields<'a, 'tcx>(ecx: &EncodeContext<'a, 'tcx>,
                                      method_ty: &ty::Method<'tcx>) {
     encode_def_id(rbml_w, method_ty.def_id);
     encode_name(rbml_w, method_ty.name);
-    encode_generics(rbml_w, ecx, &method_ty.generics,
+    encode_generics(rbml_w, ecx, &method_ty.generics, &method_ty.predicates,
                     tag_method_ty_generics);
     encode_method_fty(ecx, rbml_w, &method_ty.fty);
     encode_visibility(rbml_w, method_ty.vis);
@@ -844,15 +852,15 @@ fn encode_info_for_method<'a, 'tcx>(ecx: &EncodeContext<'a, 'tcx>,
     encode_stability(rbml_w, stab);
 
     // The type for methods gets encoded twice, which is unfortunate.
-    let pty = lookup_item_type(ecx.tcx, m.def_id);
-    encode_bounds_and_type(rbml_w, ecx, &pty);
+    encode_bounds_and_type_for_item(rbml_w, ecx, m.def_id.local_id());
 
     let elem = ast_map::PathName(m.name);
     encode_path(rbml_w, impl_path.chain(Some(elem).into_iter()));
     match ast_item_opt {
         Some(&ast::MethodImplItem(ref ast_method)) => {
             encode_attributes(rbml_w, &ast_method.attrs[]);
-            let any_types = !pty.generics.types.is_empty();
+            let scheme = ty::lookup_item_type(ecx.tcx, m.def_id);
+            let any_types = !scheme.generics.types.is_empty();
             if any_types || is_default_impl || should_inline(&ast_method.attrs[]) {
                 encode_inlined_item(ecx, rbml_w, IIImplItemRef(local_def(parent_id),
                                                                ast_item_opt.unwrap()));
@@ -887,8 +895,7 @@ fn encode_info_for_associated_type(ecx: &EncodeContext,
     encode_parent_item(rbml_w, local_def(parent_id));
     encode_item_sort(rbml_w, 't');
 
-    let type_scheme = ty::lookup_item_type(ecx.tcx, associated_type.def_id);
-    encode_bounds_and_type(rbml_w, ecx, &type_scheme);
+    encode_bounds_and_type_for_item(rbml_w, ecx, associated_type.def_id.local_id());
 
     let stab = stability::lookup(ecx.tcx, associated_type.def_id);
     encode_stability(rbml_w, stab);
@@ -1027,7 +1034,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
         } else {
             encode_family(rbml_w, 'c');
         }
-        encode_bounds_and_type(rbml_w, ecx, &lookup_item_type(tcx, def_id));
+        encode_bounds_and_type_for_item(rbml_w, ecx, item.id);
         encode_symbol(ecx, rbml_w, item.id);
         encode_name(rbml_w, item.ident.name);
         encode_path(rbml_w, path);
@@ -1041,7 +1048,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
         rbml_w.start_tag(tag_items_data_item);
         encode_def_id(rbml_w, def_id);
         encode_family(rbml_w, 'C');
-        encode_bounds_and_type(rbml_w, ecx, &lookup_item_type(tcx, def_id));
+        encode_bounds_and_type_for_item(rbml_w, ecx, item.id);
         encode_name(rbml_w, item.ident.name);
         encode_path(rbml_w, path);
         encode_attributes(rbml_w, &item.attrs);
@@ -1056,7 +1063,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
         encode_def_id(rbml_w, def_id);
         encode_family(rbml_w, FN_FAMILY);
         let tps_len = generics.ty_params.len();
-        encode_bounds_and_type(rbml_w, ecx, &lookup_item_type(tcx, def_id));
+        encode_bounds_and_type_for_item(rbml_w, ecx, item.id);
         encode_name(rbml_w, item.ident.name);
         encode_path(rbml_w, path);
         encode_attributes(rbml_w, &item.attrs[]);
@@ -1105,7 +1112,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
         rbml_w.start_tag(tag_items_data_item);
         encode_def_id(rbml_w, def_id);
         encode_family(rbml_w, 'y');
-        encode_bounds_and_type(rbml_w, ecx, &lookup_item_type(tcx, def_id));
+        encode_bounds_and_type_for_item(rbml_w, ecx, item.id);
         encode_name(rbml_w, item.ident.name);
         encode_path(rbml_w, path);
         encode_visibility(rbml_w, vis);
@@ -1119,7 +1126,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
         encode_def_id(rbml_w, def_id);
         encode_family(rbml_w, 't');
         encode_item_variances(rbml_w, ecx, item.id);
-        encode_bounds_and_type(rbml_w, ecx, &lookup_item_type(tcx, def_id));
+        encode_bounds_and_type_for_item(rbml_w, ecx, item.id);
         encode_name(rbml_w, item.ident.name);
         encode_attributes(rbml_w, &item.attrs[]);
         encode_repr_attrs(rbml_w, ecx, &item.attrs[]);
@@ -1161,7 +1168,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
         rbml_w.start_tag(tag_items_data_item);
         encode_def_id(rbml_w, def_id);
         encode_family(rbml_w, 'S');
-        encode_bounds_and_type(rbml_w, ecx, &lookup_item_type(tcx, def_id));
+        encode_bounds_and_type_for_item(rbml_w, ecx, item.id);
 
         encode_item_variances(rbml_w, ecx, item.id);
         encode_name(rbml_w, item.ident.name);
@@ -1204,7 +1211,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
         rbml_w.start_tag(tag_items_data_item);
         encode_def_id(rbml_w, def_id);
         encode_family(rbml_w, 'i');
-        encode_bounds_and_type(rbml_w, ecx, &lookup_item_type(tcx, def_id));
+        encode_bounds_and_type_for_item(rbml_w, ecx, item.id);
         encode_name(rbml_w, item.ident.name);
         encode_attributes(rbml_w, &item.attrs[]);
         encode_unsafety(rbml_w, unsafety);
@@ -1305,10 +1312,11 @@ fn encode_info_for_item(ecx: &EncodeContext,
         encode_family(rbml_w, 'I');
         encode_item_variances(rbml_w, ecx, item.id);
         let trait_def = ty::lookup_trait_def(tcx, def_id);
+        let trait_predicates = ty::lookup_predicates(tcx, def_id);
         encode_unsafety(rbml_w, trait_def.unsafety);
         encode_paren_sugar(rbml_w, trait_def.paren_sugar);
         encode_associated_type_names(rbml_w, &trait_def.associated_type_names);
-        encode_generics(rbml_w, ecx, &trait_def.generics, tag_item_generics);
+        encode_generics(rbml_w, ecx, &trait_def.generics, &trait_predicates, tag_item_generics);
         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[]);
@@ -1384,9 +1392,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
                                           METHOD_FAMILY);
                         }
                     }
-                    let pty = ty::lookup_item_type(tcx,
-                                                   method_def_id);
-                    encode_bounds_and_type(rbml_w, ecx, &pty);
+                    encode_bounds_and_type_for_item(rbml_w, ecx, method_def_id.local_id());
 
                     is_nonstatic_method = method_ty.explicit_self !=
                         ty::StaticExplicitSelfCategory;
@@ -1415,8 +1421,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
                 if is_nonstatic_method {
                     // FIXME: I feel like there is something funny
                     // going on.
-                    let pty = ty::lookup_item_type(tcx, item_def_id.def_id());
-                    encode_bounds_and_type(rbml_w, ecx, &pty);
+                    encode_bounds_and_type_for_item(rbml_w, ecx, item_def_id.def_id().local_id());
                 }
             };
             match trait_item {
@@ -1468,8 +1473,7 @@ fn encode_info_for_foreign_item(ecx: &EncodeContext,
     match nitem.node {
       ast::ForeignItemFn(ref fndecl, _) => {
         encode_family(rbml_w, FN_FAMILY);
-        encode_bounds_and_type(rbml_w, ecx,
-                               &lookup_item_type(ecx.tcx,local_def(nitem.id)));
+        encode_bounds_and_type_for_item(rbml_w, ecx, nitem.id);
         encode_name(rbml_w, nitem.ident.name);
         if abi == abi::RustIntrinsic {
             encode_inlined_item(ecx, rbml_w, IIForeignRef(nitem));
@@ -1486,8 +1490,7 @@ fn encode_info_for_foreign_item(ecx: &EncodeContext,
         } else {
             encode_family(rbml_w, 'c');
         }
-        encode_bounds_and_type(rbml_w, ecx,
-                               &lookup_item_type(ecx.tcx,local_def(nitem.id)));
+        encode_bounds_and_type_for_item(rbml_w, ecx, nitem.id);
         encode_attributes(rbml_w, &*nitem.attrs);
         let stab = stability::lookup(ecx.tcx, ast_util::local_def(nitem.id));
         encode_stability(rbml_w, stab);

src/librustc/middle/astencode.rs

@@ -951,11 +951,6 @@ impl<'a, 'tcx> rbml_writer_helpers<'tcx> for Encoder<'a> {
                         Ok(encode_vec_per_param_space(
                             this, &type_scheme.generics.regions,
                             |this, def| def.encode(this).unwrap()))
-                    });
-                    this.emit_struct_field("predicates", 2, |this| {
-                        Ok(encode_vec_per_param_space(
-                            this, &type_scheme.generics.predicates,
-                            |this, def| this.emit_predicate(ecx, def)))
                     })
                 })
             });
@@ -1574,7 +1569,7 @@ impl<'a, 'tcx> rbml_decoder_decoder_helpers<'tcx> for reader::Decoder<'a> {
 
     fn read_type_scheme<'b, 'c>(&mut self, dcx: &DecodeContext<'b, 'c, 'tcx>)
                                 -> ty::TypeScheme<'tcx> {
-        self.read_struct("TypeScheme", 2, |this| {
+        self.read_struct("TypeScheme", 3, |this| {
             Ok(ty::TypeScheme {
                 generics: this.read_struct_field("generics", 0, |this| {
                     this.read_struct("Generics", 2, |this| {
@@ -1590,12 +1585,6 @@ impl<'a, 'tcx> rbml_decoder_decoder_helpers<'tcx> for reader::Decoder<'a> {
                                 Ok(this.read_vec_per_param_space(
                                     |this| Decodable::decode(this).unwrap()))
                             }).unwrap(),
-
-                            predicates:
-                            this.read_struct_field("predicates", 2, |this| {
-                                Ok(this.read_vec_per_param_space(
-                                    |this| this.read_predicate(dcx)))
-                            }).unwrap(),
                         })
                     })
                 }).unwrap(),

src/librustc/middle/subst.rs

@@ -18,6 +18,7 @@ use middle::ty_fold::{self, TypeFoldable, TypeFolder};
 use util::ppaux::Repr;
 
 use std::fmt;
+use std::iter::IntoIterator;
 use std::slice::Iter;
 use std::vec::{Vec, IntoIter};
 use syntax::codemap::{Span, DUMMY_SP};
@@ -529,6 +530,23 @@ impl<'a,T> Iterator for EnumeratedItems<'a,T> {
     }
 }
 
+impl<T> IntoIterator for VecPerParamSpace<T> {
+    type IntoIter = IntoIter<T>;
+
+    fn into_iter(self) -> IntoIter<T> {
+        self.into_vec().into_iter()
+    }
+}
+
+impl<'a,T> IntoIterator for &'a VecPerParamSpace<T> {
+    type IntoIter = Iter<'a, T>;
+
+    fn into_iter(self) -> Iter<'a, T> {
+        self.as_slice().into_iter()
+    }
+}
+
+
 ///////////////////////////////////////////////////////////////////////////
 // Public trait `Subst`
 //

src/librustc/middle/traits/mod.rs

@@ -283,7 +283,7 @@ pub fn overlapping_impls(infcx: &InferCtxt,
 /// Creates predicate obligations from the generic bounds.
 pub fn predicates_for_generics<'tcx>(tcx: &ty::ctxt<'tcx>,
                                      cause: ObligationCause<'tcx>,
-                                     generic_bounds: &ty::GenericBounds<'tcx>)
+                                     generic_bounds: &ty::InstantiatedPredicates<'tcx>)
                                      -> PredicateObligations<'tcx>
 {
     util::predicates_for_generics(tcx, cause, 0, generic_bounds)