rustc: Store InternedString in DefPathData

Previously a `Symbol` was stored there, but this ended up causing hash
collisions in situations that otherwise shouldn't have a hash collision. Only
the symbol's string value was hashed, but it was possible for distinct symbols
to have the same string value, fooling various calcuations into thinking that
these paths *didn't* need disambiguating data when in fact they did!

By storing `InternedString` instead we're hopefully triggering all the exising
logic to disambiguate paths with same-name `Symbol` but actually distinct
locations.

Author: alexcrichton

src/librustc/hir/lowering.rs

@@ -2863,7 +2863,7 @@ impl<'a> LoweringContext<'a> {
         let parent_def = self.parent_def.unwrap();
         let def_id = {
             let defs = self.resolver.definitions();
-            let def_path_data = DefPathData::Binding(name);
+            let def_path_data = DefPathData::Binding(name.as_str());
             let def_index = defs.create_def_with_parent(parent_def,
                                                         node_id,
                                                         def_path_data,

src/librustc/hir/map/def_collector.rs

@@ -104,14 +104,14 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
                 DefPathData::Impl,
             ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) | ItemKind::Trait(..) |
             ItemKind::ExternCrate(..) | ItemKind::ForeignMod(..) | ItemKind::Ty(..) =>
-                DefPathData::TypeNs(i.ident.name),
+                DefPathData::TypeNs(i.ident.name.as_str()),
             ItemKind::Mod(..) if i.ident == keywords::Invalid.ident() => {
                 return visit::walk_item(self, i);
             }
-            ItemKind::Mod(..) => DefPathData::Module(i.ident.name),
+            ItemKind::Mod(..) => DefPathData::Module(i.ident.name.as_str()),
             ItemKind::Static(..) | ItemKind::Const(..) | ItemKind::Fn(..) =>
-                DefPathData::ValueNs(i.ident.name),
-            ItemKind::MacroDef(..) => DefPathData::MacroDef(i.ident.name),
+                DefPathData::ValueNs(i.ident.name.as_str()),
+            ItemKind::MacroDef(..) => DefPathData::MacroDef(i.ident.name.as_str()),
             ItemKind::Mac(..) => return self.visit_macro_invoc(i.id, false),
             ItemKind::GlobalAsm(..) => DefPathData::Misc,
             ItemKind::Use(ref view_path) => {
@@ -139,13 +139,15 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
                     for v in &enum_definition.variants {
                         let variant_def_index =
                             this.create_def(v.node.data.id(),
-                                            DefPathData::EnumVariant(v.node.name.name),
+                                            DefPathData::EnumVariant(v.node.name.name.as_str()),
                                             REGULAR_SPACE);
                         this.with_parent(variant_def_index, |this| {
                             for (index, field) in v.node.data.fields().iter().enumerate() {
                                 let name = field.ident.map(|ident| ident.name)
                                     .unwrap_or_else(|| Symbol::intern(&index.to_string()));
-                                this.create_def(field.id, DefPathData::Field(name), REGULAR_SPACE);
+                                this.create_def(field.id,
+                                                DefPathData::Field(name.as_str()),
+                                                REGULAR_SPACE);
                             }
 
                             if let Some(ref expr) = v.node.disr_expr {
@@ -165,7 +167,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
                     for (index, field) in struct_def.fields().iter().enumerate() {
                         let name = field.ident.map(|ident| ident.name)
                             .unwrap_or_else(|| Symbol::intern(&index.to_string()));
-                        this.create_def(field.id, DefPathData::Field(name), REGULAR_SPACE);
+                        this.create_def(field.id, DefPathData::Field(name.as_str()), REGULAR_SPACE);
                     }
                 }
                 _ => {}
@@ -176,7 +178,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
 
     fn visit_foreign_item(&mut self, foreign_item: &'a ForeignItem) {
         let def = self.create_def(foreign_item.id,
-                                  DefPathData::ValueNs(foreign_item.ident.name),
+                                  DefPathData::ValueNs(foreign_item.ident.name.as_str()),
                                   REGULAR_SPACE);
 
         self.with_parent(def, |this| {
@@ -187,7 +189,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
     fn visit_generics(&mut self, generics: &'a Generics) {
         for ty_param in generics.ty_params.iter() {
             self.create_def(ty_param.id,
-                            DefPathData::TypeParam(ty_param.ident.name),
+                            DefPathData::TypeParam(ty_param.ident.name.as_str()),
                             REGULAR_SPACE);
         }
 
@@ -197,8 +199,8 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
     fn visit_trait_item(&mut self, ti: &'a TraitItem) {
         let def_data = match ti.node {
             TraitItemKind::Method(..) | TraitItemKind::Const(..) =>
-                DefPathData::ValueNs(ti.ident.name),
-            TraitItemKind::Type(..) => DefPathData::TypeNs(ti.ident.name),
+                DefPathData::ValueNs(ti.ident.name.as_str()),
+            TraitItemKind::Type(..) => DefPathData::TypeNs(ti.ident.name.as_str()),
             TraitItemKind::Macro(..) => return self.visit_macro_invoc(ti.id, false),
         };
 
@@ -215,8 +217,8 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
     fn visit_impl_item(&mut self, ii: &'a ImplItem) {
         let def_data = match ii.node {
             ImplItemKind::Method(..) | ImplItemKind::Const(..) =>
-                DefPathData::ValueNs(ii.ident.name),
-            ImplItemKind::Type(..) => DefPathData::TypeNs(ii.ident.name),
+                DefPathData::ValueNs(ii.ident.name.as_str()),
+            ImplItemKind::Type(..) => DefPathData::TypeNs(ii.ident.name.as_str()),
             ImplItemKind::Macro(..) => return self.visit_macro_invoc(ii.id, false),
         };
 
@@ -237,7 +239,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
             PatKind::Mac(..) => return self.visit_macro_invoc(pat.id, false),
             PatKind::Ident(_, id, _) => {
                 let def = self.create_def(pat.id,
-                                          DefPathData::Binding(id.node.name),
+                                          DefPathData::Binding(id.node.name.as_str()),
                                           REGULAR_SPACE);
                 self.parent_def = Some(def);
             }
@@ -282,7 +284,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
 
     fn visit_lifetime_def(&mut self, def: &'a LifetimeDef) {
         self.create_def(def.lifetime.id,
-                        DefPathData::LifetimeDef(def.lifetime.ident.name),
+                        DefPathData::LifetimeDef(def.lifetime.ident.name.as_str()),
                         REGULAR_SPACE);
     }
 

src/librustc/hir/map/definitions.rs

@@ -80,8 +80,10 @@ impl DefPathTable {
 
     #[inline(always)]
     pub fn def_path_hash(&self, index: DefIndex) -> DefPathHash {
-        self.def_path_hashes[index.address_space().index()]
-                            [index.as_array_index()]
+        let ret = self.def_path_hashes[index.address_space().index()]
+                                      [index.as_array_index()];
+        debug!("def_path_hash({:?}) = {:?}", index, ret);
+        return ret
     }
 
     pub fn add_def_path_hashes_to(&self,
@@ -213,7 +215,7 @@ impl DefKey {
             DefPathData::Binding(name) |
             DefPathData::Field(name) |
             DefPathData::GlobalMetaData(name) => {
-                (*name.as_str()).hash(&mut hasher);
+                name.hash(&mut hasher);
             }
 
             DefPathData::Impl |
@@ -347,31 +349,31 @@ pub enum DefPathData {
     /// An impl
     Impl,
     /// Something in the type NS
-    TypeNs(Symbol),
+    TypeNs(InternedString),
     /// Something in the value NS
-    ValueNs(Symbol),
+    ValueNs(InternedString),
     /// A module declaration
-    Module(Symbol),
+    Module(InternedString),
     /// A macro rule
-    MacroDef(Symbol),
+    MacroDef(InternedString),
     /// A closure expression
     ClosureExpr,
 
     // Subportions of items
     /// A type parameter (generic parameter)
-    TypeParam(Symbol),
+    TypeParam(InternedString),
     /// A lifetime definition
-    LifetimeDef(Symbol),
+    LifetimeDef(InternedString),
     /// A variant of a enum
-    EnumVariant(Symbol),
+    EnumVariant(InternedString),
     /// A struct field
-    Field(Symbol),
+    Field(InternedString),
     /// Implicit ctor for a tuple-like struct
     StructCtor,
     /// Initializer for a const
     Initializer,
     /// Pattern binding
-    Binding(Symbol),
+    Binding(InternedString),
     /// An `impl Trait` type node.
     ImplTrait,
     /// A `typeof` type node.
@@ -380,7 +382,7 @@ pub enum DefPathData {
     /// GlobalMetaData identifies a piece of crate metadata that is global to
     /// a whole crate (as opposed to just one item). GlobalMetaData components
     /// are only supposed to show up right below the crate root.
-    GlobalMetaData(Symbol)
+    GlobalMetaData(InternedString)
 }
 
 #[derive(Copy, Clone, Hash, PartialEq, Eq, PartialOrd, Ord, Debug,
@@ -601,7 +603,7 @@ impl Definitions {
 }
 
 impl DefPathData {
-    pub fn get_opt_name(&self) -> Option<Symbol> {
+    pub fn get_opt_name(&self) -> Option<InternedString> {
         use self::DefPathData::*;
         match *self {
             TypeNs(name) |
@@ -639,7 +641,7 @@ impl DefPathData {
             Binding(name) |
             Field(name) |
             GlobalMetaData(name) => {
-                return name.as_str();
+                return name
             }
 
             // note that this does not show up in user printouts
@@ -684,7 +686,7 @@ macro_rules! define_global_metadata_kind {
                     definitions.create_def_with_parent(
                         CRATE_DEF_INDEX,
                         ast::DUMMY_NODE_ID,
-                        DefPathData::GlobalMetaData(instance.name()),
+                        DefPathData::GlobalMetaData(instance.name().as_str()),
                         GLOBAL_MD_ADDRESS_SPACE,
                         Mark::root()
                     );
@@ -698,7 +700,7 @@ macro_rules! define_global_metadata_kind {
                 let def_key = DefKey {
                     parent: Some(CRATE_DEF_INDEX),
                     disambiguated_data: DisambiguatedDefPathData {
-                        data: DefPathData::GlobalMetaData(self.name()),
+                        data: DefPathData::GlobalMetaData(self.name().as_str()),
                         disambiguator: 0,
                     }
                 };

src/librustc/traits/error_reporting.rs

@@ -348,7 +348,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             //
             // Currently I'm leaving it for what I need for `try`.
             if self.tcx.trait_of_item(item) == Some(trait_ref.def_id) {
-                method = self.tcx.item_name(item).as_str();
+                method = self.tcx.item_name(item);
                 flags.push(("from_method", None));
                 flags.push(("from_method", Some(&*method)));
             }

src/librustc/traits/on_unimplemented.rs

@@ -227,7 +227,7 @@ impl<'a, 'gcx, 'tcx> OnUnimplementedFormatString {
               span: Span)
               -> Result<(), ErrorReported>
     {
-        let name = tcx.item_name(trait_def_id).as_str();
+        let name = tcx.item_name(trait_def_id);
         let generics = tcx.generics_of(trait_def_id);
         let parser = Parser::new(&self.0);
         let types = &generics.types;
@@ -272,7 +272,7 @@ impl<'a, 'gcx, 'tcx> OnUnimplementedFormatString {
                   trait_ref: ty::TraitRef<'tcx>)
                   -> String
     {
-        let name = tcx.item_name(trait_ref.def_id).as_str();
+        let name = tcx.item_name(trait_ref.def_id);
         let trait_str = tcx.item_path_str(trait_ref.def_id);
         let generics = tcx.generics_of(trait_ref.def_id);
         let generic_map = generics.types.iter().map(|param| {

src/librustc/ty/item_path.rs

@@ -13,6 +13,7 @@ use hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
 use ty::{self, Ty, TyCtxt};
 use syntax::ast;
 use syntax::symbol::Symbol;
+use syntax::symbol::InternedString;
 
 use std::cell::Cell;
 
@@ -130,20 +131,20 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
     {
         let visible_parent_map = self.visible_parent_map(LOCAL_CRATE);
 
-        let (mut cur_def, mut cur_path) = (external_def_id, Vec::<ast::Name>::new());
+        let (mut cur_def, mut cur_path) = (external_def_id, Vec::<InternedString>::new());
         loop {
             // If `cur_def` is a direct or injected extern crate, push the path to the crate
             // followed by the path to the item within the crate and return.
             if cur_def.index == CRATE_DEF_INDEX {
                 match *self.extern_crate(cur_def) {
                     Some(ref extern_crate) if extern_crate.direct => {
                         self.push_item_path(buffer, extern_crate.def_id);
-                        cur_path.iter().rev().map(|segment| buffer.push(&segment.as_str())).count();
+                        cur_path.iter().rev().map(|segment| buffer.push(&segment)).count();
                         return true;
                     }
                     None => {
                         buffer.push(&self.crate_name(cur_def.krate).as_str());
-                        cur_path.iter().rev().map(|segment| buffer.push(&segment.as_str())).count();
+                        cur_path.iter().rev().map(|segment| buffer.push(&segment)).count();
                         return true;
                     }
                     _ => {},
@@ -152,7 +153,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 
             cur_path.push(self.sess.cstore.def_key(cur_def)
                               .disambiguated_data.data.get_opt_name().unwrap_or_else(||
-                Symbol::intern("<unnamed>")));
+                Symbol::intern("<unnamed>").as_str()));
             match visible_parent_map.get(&cur_def) {
                 Some(&def) => cur_def = def,
                 None => return false,

src/librustc/ty/maps.rs

@@ -20,7 +20,6 @@ use middle::cstore::{ExternCrate, LinkagePreference, NativeLibrary};
 use middle::cstore::{NativeLibraryKind, DepKind, CrateSource};
 use middle::privacy::AccessLevels;
 use middle::region;
-use middle::region::RegionMaps;
 use middle::resolve_lifetime::{Region, ObjectLifetimeDefault};
 use middle::stability::{self, DeprecationEntry};
 use middle::lang_items::{LanguageItems, LangItem};

src/librustc/ty/mod.rs

@@ -2206,11 +2206,11 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         }
     }
 
-    pub fn item_name(self, id: DefId) -> ast::Name {
+    pub fn item_name(self, id: DefId) -> InternedString {
         if let Some(id) = self.hir.as_local_node_id(id) {
-            self.hir.name(id)
+            self.hir.name(id).as_str()
         } else if id.index == CRATE_DEF_INDEX {
-            self.original_crate_name(id.krate)
+            self.original_crate_name(id.krate).as_str()
         } else {
             let def_key = self.sess.cstore.def_key(id);
             // The name of a StructCtor is that of its struct parent.

src/librustc_const_eval/eval.rs

@@ -327,7 +327,7 @@ fn eval_const_expr_partial<'a, 'tcx>(cx: &ConstContext<'a, 'tcx>,
                     ConstEvalErr { span: e.span, kind: LayoutError(err) }
                 })
             };
-            match &tcx.item_name(def_id).as_str()[..] {
+            match &tcx.item_name(def_id)[..] {
                 "size_of" => {
                     let size = layout_of(substs.type_at(0))?.size(tcx);
                     return Ok(Integral(Usize(ConstUsize::new(size.bytes(),

src/librustc_driver/test.rs

@@ -18,7 +18,6 @@ use rustc_trans;
 use rustc::middle::free_region::FreeRegionMap;
 use rustc::middle::region;
 use rustc::middle::resolve_lifetime;
-use rustc::middle::stability;
 use rustc::ty::subst::{Kind, Subst};
 use rustc::traits::{ObligationCause, Reveal};
 use rustc::ty::{self, Ty, TyCtxt, TypeFoldable};
@@ -140,7 +139,6 @@ fn test_env<F>(source_string: &str,
 
     // run just enough stuff to build a tcx:
     let named_region_map = resolve_lifetime::krate(&sess, &hir_map);
-    let index = stability::Index::new(&sess);
     TyCtxt::create_and_enter(&sess,
                              ty::maps::Providers::default(),
                              ty::maps::Providers::default(),
@@ -150,7 +148,6 @@ fn test_env<F>(source_string: &str,
                              resolutions,
                              named_region_map.unwrap(),
                              hir_map,
-                             index,
                              "test_crate",
                              |tcx| {
         tcx.infer_ctxt().enter(|infcx| {

src/librustc_metadata/cstore_impl.rs

@@ -40,7 +40,6 @@ use syntax::parse::filemap_to_stream;
 use syntax::symbol::Symbol;
 use syntax_pos::{Span, NO_EXPANSION};
 use rustc_data_structures::indexed_set::IdxSetBuf;
-use rustc::hir::svh::Svh;
 use rustc::hir;
 
 macro_rules! provide {
@@ -469,7 +468,7 @@ impl CrateStore for cstore::CStore {
             .insert(local_span, (name.to_string(), data.get_span(id.index, sess)));
 
         LoadedMacro::MacroDef(ast::Item {
-            ident: ast::Ident::with_empty_ctxt(name),
+            ident: ast::Ident::from_str(&name),
             id: ast::DUMMY_NODE_ID,
             span: local_span,
             attrs: attrs.iter().cloned().collect(),