Auto merge of #37824 - jseyfried:symbols, r=eddyb

Clean up `ast::Attribute`, `ast::CrateConfig`, and string interning

This PR
 - removes `ast::Attribute_` (changing `Attribute` from `Spanned<Attribute_>` to a struct),
 - moves a `MetaItem`'s name from the `MetaItemKind` variants to a field of `MetaItem`,
 - avoids needlessly wrapping `ast::MetaItem` with `P`,
 - moves string interning into `syntax::symbol` (`ast::Name` is a reexport of `symbol::Symbol` for now),
 - replaces `InternedString` with `Symbol` in the AST, HIR, and various other places, and
 - refactors `ast::CrateConfig` from a `Vec` to a `HashSet`.

r? @eddyb

src/libproc_macro_plugin/qquote.rs

@@ -34,8 +34,9 @@ use syntax::codemap::Span;
 use syntax::ext::base::*;
 use syntax::ext::base;
 use syntax::ext::proc_macro_shim::build_block_emitter;
-use syntax::parse::token::{self, Token, gensym_ident, str_to_ident};
+use syntax::parse::token::{self, Token};
 use syntax::print::pprust;
+use syntax::symbol::Symbol;
 use syntax::tokenstream::{TokenTree, TokenStream};
 
 // ____________________________________________________________________________________________
@@ -124,7 +125,7 @@ fn qquote_iter<'cx>(cx: &'cx mut ExtCtxt, depth: i64, ts: TokenStream) -> (Bindi
                     } // produce an error or something first
                     let exp = vec![exp.unwrap().to_owned()];
                     debug!("RHS: {:?}", exp.clone());
-                    let new_id = gensym_ident("tmp");
+                    let new_id = Ident::with_empty_ctxt(Symbol::gensym("tmp"));
                     debug!("RHS TS: {:?}", TokenStream::from_tts(exp.clone()));
                     debug!("RHS TS TT: {:?}", TokenStream::from_tts(exp.clone()).to_vec());
                     bindings.push((new_id, TokenStream::from_tts(exp)));
@@ -179,7 +180,7 @@ fn unravel_concats(tss: Vec<TokenStream>) -> TokenStream {
     };
 
     while let Some(ts) = pushes.pop() {
-        output = build_fn_call(str_to_ident("concat"),
+        output = build_fn_call(Ident::from_str("concat"),
                                concat(concat(ts,
                                              from_tokens(vec![Token::Comma])),
                                       output));
@@ -209,18 +210,19 @@ fn convert_complex_tts<'cx>(cx: &'cx mut ExtCtxt, tts: Vec<QTT>) -> (Bindings, T
             // FIXME handle sequence repetition tokens
             QTT::QDL(qdl) => {
                 debug!("  QDL: {:?} ", qdl.tts);
-                let new_id = gensym_ident("qdl_tmp");
+                let new_id = Ident::with_empty_ctxt(Symbol::gensym("qdl_tmp"));
                 let mut cct_rec = convert_complex_tts(cx, qdl.tts);
                 bindings.append(&mut cct_rec.0);
                 bindings.push((new_id, cct_rec.1));
 
                 let sep = build_delim_tok(qdl.delim);
 
-                pushes.push(build_mod_call(vec![str_to_ident("proc_macro_tokens"),
-                                               str_to_ident("build"),
-                                               str_to_ident("build_delimited")],
-                                          concat(from_tokens(vec![Token::Ident(new_id)]),
-                                                 concat(lex(","), sep))));
+                pushes.push(build_mod_call(
+                    vec![Ident::from_str("proc_macro_tokens"),
+                         Ident::from_str("build"),
+                         Ident::from_str("build_delimited")],
+                    concat(from_tokens(vec![Token::Ident(new_id)]), concat(lex(","), sep)),
+                ));
             }
             QTT::QIdent(t) => {
                 pushes.push(TokenStream::from_tts(vec![t]));
@@ -250,13 +252,13 @@ fn unravel(binds: Bindings) -> TokenStream {
 
 /// Checks if the Ident is `unquote`.
 fn is_unquote(id: Ident) -> bool {
-    let qq = str_to_ident("unquote");
+    let qq = Ident::from_str("unquote");
     id.name == qq.name  // We disregard context; unquote is _reserved_
 }
 
 /// Checks if the Ident is `quote`.
 fn is_qquote(id: Ident) -> bool {
-    let qq = str_to_ident("qquote");
+    let qq = Ident::from_str("qquote");
     id.name == qq.name  // We disregard context; qquote is _reserved_
 }
 
@@ -266,7 +268,8 @@ mod int_build {
 
     use syntax::ast::{self, Ident};
     use syntax::codemap::{DUMMY_SP};
-    use syntax::parse::token::{self, Token, keywords, str_to_ident};
+    use syntax::parse::token::{self, Token, Lit};
+    use syntax::symbol::keywords;
     use syntax::tokenstream::{TokenTree, TokenStream};
 
     // ____________________________________________________________________________________________
@@ -277,19 +280,19 @@ mod int_build {
                build_paren_delimited(build_vec(build_token_tt(t))))
     }
 
-    pub fn emit_lit(l: token::Lit, n: Option<ast::Name>) -> TokenStream {
+    pub fn emit_lit(l: Lit, n: Option<ast::Name>) -> TokenStream {
         let suf = match n {
-            Some(n) => format!("Some(ast::Name({}))", n.0),
+            Some(n) => format!("Some(ast::Name({}))", n.as_u32()),
             None => "None".to_string(),
         };
 
         let lit = match l {
-            token::Lit::Byte(n) => format!("Lit::Byte(token::intern(\"{}\"))", n.to_string()),
-            token::Lit::Char(n) => format!("Lit::Char(token::intern(\"{}\"))", n.to_string()),
-            token::Lit::Integer(n) => format!("Lit::Integer(token::intern(\"{}\"))", n.to_string()),
-            token::Lit::Float(n) => format!("Lit::Float(token::intern(\"{}\"))", n.to_string()),
-            token::Lit::Str_(n) => format!("Lit::Str_(token::intern(\"{}\"))", n.to_string()),
-            token::Lit::ByteStr(n) => format!("Lit::ByteStr(token::intern(\"{}\"))", n.to_string()),
+            Lit::Byte(n) => format!("Lit::Byte(Symbol::intern(\"{}\"))", n.to_string()),
+            Lit::Char(n) => format!("Lit::Char(Symbol::intern(\"{}\"))", n.to_string()),
+            Lit::Float(n) => format!("Lit::Float(Symbol::intern(\"{}\"))", n.to_string()),
+            Lit::Str_(n) => format!("Lit::Str_(Symbol::intern(\"{}\"))", n.to_string()),
+            Lit::Integer(n) => format!("Lit::Integer(Symbol::intern(\"{}\"))", n.to_string()),
+            Lit::ByteStr(n) => format!("Lit::ByteStr(Symbol::intern(\"{}\"))", n.to_string()),
             _ => panic!("Unsupported literal"),
         };
 
@@ -388,9 +391,10 @@ mod int_build {
             Token::Underscore => lex("_"),
             Token::Literal(lit, sfx) => emit_lit(lit, sfx),
             // fix ident expansion information... somehow
-            Token::Ident(ident) => lex(&format!("Token::Ident(str_to_ident(\"{}\"))", ident.name)),
-            Token::Lifetime(ident) => lex(&format!("Token::Ident(str_to_ident(\"{}\"))",
-                                                   ident.name)),
+            Token::Ident(ident) =>
+                lex(&format!("Token::Ident(Ident::from_str(\"{}\"))", ident.name)),
+            Token::Lifetime(ident) =>
+                lex(&format!("Token::Ident(Ident::from_str(\"{}\"))", ident.name)),
             _ => panic!("Unhandled case!"),
         }
     }
@@ -408,7 +412,7 @@ mod int_build {
 
     /// Takes `input` and returns `vec![input]`.
     pub fn build_vec(ts: TokenStream) -> TokenStream {
-        build_mac_call(str_to_ident("vec"), ts)
+        build_mac_call(Ident::from_str("vec"), ts)
         // tts.clone().to_owned()
     }
 

src/libproc_macro_tokens/build.rs

@@ -13,7 +13,8 @@ extern crate syntax_pos;
 
 use syntax::ast::Ident;
 use syntax::codemap::DUMMY_SP;
-use syntax::parse::token::{self, Token, keywords, str_to_ident};
+use syntax::parse::token::{self, Token};
+use syntax::symbol::keywords;
 use syntax::tokenstream::{self, TokenTree, TokenStream};
 use std::rc::Rc;
 
@@ -43,13 +44,13 @@ pub fn ident_eq(tident: &TokenTree, id: Ident) -> bool {
 
 /// Convert a `&str` into a Token.
 pub fn str_to_token_ident(s: &str) -> Token {
-    Token::Ident(str_to_ident(s))
+    Token::Ident(Ident::from_str(s))
 }
 
 /// Converts a keyword (from `syntax::parse::token::keywords`) into a Token that
 /// corresponds to it.
 pub fn keyword_to_token_ident(kw: keywords::Keyword) -> Token {
-    Token::Ident(str_to_ident(&kw.name().as_str()[..]))
+    Token::Ident(Ident::from_str(&kw.name().as_str()[..]))
 }
 
 // ____________________________________________________________________________________________

src/librustc/hir/check_attr.rs

@@ -64,7 +64,7 @@ impl<'a> CheckAttrVisitor<'a> {
                 None => continue,
             };
 
-            let (message, label) = match &*name {
+            let (message, label) = match &*name.as_str() {
                 "C" => {
                     conflicting_reprs += 1;
                     if target != Target::Struct &&
@@ -120,7 +120,7 @@ impl<'a> CheckAttrVisitor<'a> {
     }
 
     fn check_attribute(&self, attr: &ast::Attribute, target: Target) {
-        let name: &str = &attr.name();
+        let name: &str = &attr.name().as_str();
         match name {
             "inline" => self.check_inline(attr, target),
             "repr" => self.check_repr(attr, target),

src/librustc/hir/lowering.rs

@@ -53,8 +53,8 @@ use syntax::ast::*;
 use syntax::errors;
 use syntax::ptr::P;
 use syntax::codemap::{respan, Spanned};
-use syntax::parse::token;
 use syntax::std_inject;
+use syntax::symbol::{Symbol, keywords};
 use syntax::visit::{self, Visitor};
 use syntax_pos::Span;
 
@@ -149,7 +149,7 @@ impl<'a> LoweringContext<'a> {
     }
 
     fn str_to_ident(&self, s: &'static str) -> Name {
-        token::gensym(s)
+        Symbol::gensym(s)
     }
 
     fn with_parent_def<T, F>(&mut self, parent_id: NodeId, f: F) -> T
@@ -400,8 +400,8 @@ impl<'a> LoweringContext<'a> {
         // Don't expose `Self` (recovered "keyword used as ident" parse error).
         // `rustc::ty` expects `Self` to be only used for a trait's `Self`.
         // Instead, use gensym("Self") to create a distinct name that looks the same.
-        if name == token::keywords::SelfType.name() {
-            name = token::gensym("Self");
+        if name == keywords::SelfType.name() {
+            name = Symbol::gensym("Self");
         }
 
         hir::TyParam {
@@ -540,7 +540,7 @@ impl<'a> LoweringContext<'a> {
         hir::StructField {
             span: f.span,
             id: f.id,
-            name: f.ident.map(|ident| ident.name).unwrap_or(token::intern(&index.to_string())),
+            name: f.ident.map(|ident| ident.name).unwrap_or(Symbol::intern(&index.to_string())),
             vis: self.lower_visibility(&f.vis),
             ty: self.lower_ty(&f.ty),
             attrs: self.lower_attrs(&f.attrs),
@@ -1189,7 +1189,7 @@ impl<'a> LoweringContext<'a> {
                                                                           e.span,
                                                                           hir::PopUnstableBlock,
                                                                           ThinVec::new());
-                                this.field(token::intern(s), signal_block, ast_expr.span)
+                                this.field(Symbol::intern(s), signal_block, ast_expr.span)
                             }).collect();
                             let attrs = ast_expr.attrs.clone();
 
@@ -1953,9 +1953,9 @@ impl<'a> LoweringContext<'a> {
     fn std_path_components(&mut self, components: &[&str]) -> Vec<Name> {
         let mut v = Vec::new();
         if let Some(s) = self.crate_root {
-            v.push(token::intern(s));
+            v.push(Symbol::intern(s));
         }
-        v.extend(components.iter().map(|s| token::intern(s)));
+        v.extend(components.iter().map(|s| Symbol::intern(s)));
         return v;
     }
 

src/librustc/hir/map/def_collector.rs

@@ -19,7 +19,7 @@ use middle::cstore::InlinedItem;
 use syntax::ast::*;
 use syntax::ext::hygiene::Mark;
 use syntax::visit;
-use syntax::parse::token::{self, keywords};
+use syntax::symbol::{Symbol, keywords};
 
 /// Creates def ids for nodes in the HIR.
 pub struct DefCollector<'a> {
@@ -169,7 +169,7 @@ impl<'a> visit::Visitor for DefCollector<'a> {
                         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(|| token::intern(&index.to_string()));
+                                    .unwrap_or_else(|| Symbol::intern(&index.to_string()));
                                 this.create_def(field.id, DefPathData::Field(name.as_str()));
                             }
 
@@ -188,7 +188,7 @@ impl<'a> visit::Visitor for DefCollector<'a> {
 
                     for (index, field) in struct_def.fields().iter().enumerate() {
                         let name = field.ident.map(|ident| ident.name.as_str())
-                            .unwrap_or(token::intern(&index.to_string()).as_str());
+                            .unwrap_or(Symbol::intern(&index.to_string()).as_str());
                         this.create_def(field.id, DefPathData::Field(name));
                     }
                 }

src/librustc/hir/map/definitions.rs

@@ -14,7 +14,7 @@ use std::fmt::Write;
 use std::hash::{Hash, Hasher};
 use std::collections::hash_map::DefaultHasher;
 use syntax::ast;
-use syntax::parse::token::{self, InternedString};
+use syntax::symbol::{Symbol, InternedString};
 use ty::TyCtxt;
 use util::nodemap::NodeMap;
 
@@ -115,9 +115,9 @@ impl DefPath {
     pub fn to_string(&self, tcx: TyCtxt) -> String {
         let mut s = String::with_capacity(self.data.len() * 16);
 
-        s.push_str(&tcx.original_crate_name(self.krate));
+        s.push_str(&tcx.original_crate_name(self.krate).as_str());
         s.push_str("/");
-        s.push_str(&tcx.crate_disambiguator(self.krate));
+        s.push_str(&tcx.crate_disambiguator(self.krate).as_str());
 
         for component in &self.data {
             write!(s,
@@ -137,8 +137,8 @@ impl DefPath {
     }
 
     pub fn deterministic_hash_to<H: Hasher>(&self, tcx: TyCtxt, state: &mut H) {
-        tcx.original_crate_name(self.krate).hash(state);
-        tcx.crate_disambiguator(self.krate).hash(state);
+        tcx.original_crate_name(self.krate).as_str().hash(state);
+        tcx.crate_disambiguator(self.krate).as_str().hash(state);
         self.data.hash(state);
     }
 }
@@ -328,7 +328,7 @@ impl DefPathData {
             LifetimeDef(ref name) |
             EnumVariant(ref name) |
             Binding(ref name) |
-            Field(ref name) => Some(token::intern(name)),
+            Field(ref name) => Some(Symbol::intern(name)),
 
             Impl |
             CrateRoot |
@@ -343,7 +343,7 @@ impl DefPathData {
 
     pub fn as_interned_str(&self) -> InternedString {
         use self::DefPathData::*;
-        match *self {
+        let s = match *self {
             TypeNs(ref name) |
             ValueNs(ref name) |
             Module(ref name) |
@@ -353,43 +353,24 @@ impl DefPathData {
             EnumVariant(ref name) |
             Binding(ref name) |
             Field(ref name) => {
-                name.clone()
-            }
-
-            Impl => {
-                InternedString::new("{{impl}}")
+                return name.clone();
             }
 
             // note that this does not show up in user printouts
-            CrateRoot => {
-                InternedString::new("{{root}}")
-            }
+            CrateRoot => "{{root}}",
 
             // note that this does not show up in user printouts
-            InlinedRoot(_) => {
-                InternedString::new("{{inlined-root}}")
-            }
+            InlinedRoot(_) => "{{inlined-root}}",
 
-            Misc => {
-                InternedString::new("{{?}}")
-            }
+            Impl => "{{impl}}",
+            Misc => "{{?}}",
+            ClosureExpr => "{{closure}}",
+            StructCtor => "{{constructor}}",
+            Initializer => "{{initializer}}",
+            ImplTrait => "{{impl-Trait}}",
+        };
 
-            ClosureExpr => {
-                InternedString::new("{{closure}}")
-            }
-
-            StructCtor => {
-                InternedString::new("{{constructor}}")
-            }
-
-            Initializer => {
-                InternedString::new("{{initializer}}")
-            }
-
-            ImplTrait => {
-                InternedString::new("{{impl-Trait}}")
-            }
-        }
+        Symbol::intern(s).as_str()
     }
 
     pub fn to_string(&self) -> String {

src/librustc/hir/map/mod.rs

@@ -765,7 +765,7 @@ impl<'a, 'ast> NodesMatchingSuffix<'a, 'ast> {
                 None => return false,
                 Some((node_id, name)) => (node_id, name),
             };
-            if &part[..] != mod_name.as_str() {
+            if mod_name != &**part {
                 return false;
             }
             cursor = self.map.get_parent(mod_id);
@@ -803,8 +803,7 @@ impl<'a, 'ast> NodesMatchingSuffix<'a, 'ast> {
     // We are looking at some node `n` with a given name and parent
     // id; do their names match what I am seeking?
     fn matches_names(&self, parent_of_n: NodeId, name: Name) -> bool {
-        name.as_str() == &self.item_name[..] &&
-            self.suffix_matches(parent_of_n)
+        name == &**self.item_name && self.suffix_matches(parent_of_n)
     }
 }
 

src/librustc/hir/mod.rs

@@ -40,8 +40,8 @@ use syntax::codemap::{self, respan, Spanned};
 use syntax::abi::Abi;
 use syntax::ast::{Name, NodeId, DUMMY_NODE_ID, AsmDialect};
 use syntax::ast::{Attribute, Lit, StrStyle, FloatTy, IntTy, UintTy, MetaItem};
-use syntax::parse::token::{keywords, InternedString};
 use syntax::ptr::P;
+use syntax::symbol::{Symbol, keywords};
 use syntax::tokenstream::TokenTree;
 use syntax::util::ThinVec;
 
@@ -1163,18 +1163,18 @@ pub enum Ty_ {
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub struct InlineAsmOutput {
-    pub constraint: InternedString,
+    pub constraint: Symbol,
     pub is_rw: bool,
     pub is_indirect: bool,
 }
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub struct InlineAsm {
-    pub asm: InternedString,
+    pub asm: Symbol,
     pub asm_str_style: StrStyle,
     pub outputs: HirVec<InlineAsmOutput>,
-    pub inputs: HirVec<InternedString>,
-    pub clobbers: HirVec<InternedString>,
+    pub inputs: HirVec<Symbol>,
+    pub clobbers: HirVec<Symbol>,
     pub volatile: bool,
     pub alignstack: bool,
     pub dialect: AsmDialect,

src/librustc/hir/print.rs

@@ -13,13 +13,14 @@ pub use self::AnnNode::*;
 use syntax::abi::Abi;
 use syntax::ast;
 use syntax::codemap::{CodeMap, Spanned};
-use syntax::parse::token::{self, keywords, BinOpToken};
+use syntax::parse::token::{self, BinOpToken};
 use syntax::parse::lexer::comments;
 use syntax::print::pp::{self, break_offset, word, space, hardbreak};
 use syntax::print::pp::{Breaks, eof};
 use syntax::print::pp::Breaks::{Consistent, Inconsistent};
 use syntax::print::pprust::{self as ast_pp, PrintState};
 use syntax::ptr::P;
+use syntax::symbol::keywords;
 use syntax_pos::{self, BytePos};
 use errors;
 
@@ -1499,19 +1500,19 @@ impl<'a> State<'a> {
             hir::ExprInlineAsm(ref a, ref outputs, ref inputs) => {
                 word(&mut self.s, "asm!")?;
                 self.popen()?;
-                self.print_string(&a.asm, a.asm_str_style)?;
+                self.print_string(&a.asm.as_str(), a.asm_str_style)?;
                 self.word_space(":")?;
 
                 let mut out_idx = 0;
                 self.commasep(Inconsistent, &a.outputs, |s, out| {
-                    let mut ch = out.constraint.chars();
+                    let constraint = out.constraint.as_str();
+                    let mut ch = constraint.chars();
                     match ch.next() {
                         Some('=') if out.is_rw => {
                             s.print_string(&format!("+{}", ch.as_str()),
                                            ast::StrStyle::Cooked)?
                         }
-                        _ => s.print_string(&out.constraint,
-                                            ast::StrStyle::Cooked)?,
+                        _ => s.print_string(&constraint, ast::StrStyle::Cooked)?,
                     }
                     s.popen()?;
                     s.print_expr(&outputs[out_idx])?;
@@ -1524,7 +1525,7 @@ impl<'a> State<'a> {
 
                 let mut in_idx = 0;
                 self.commasep(Inconsistent, &a.inputs, |s, co| {
-                    s.print_string(&co, ast::StrStyle::Cooked)?;
+                    s.print_string(&co.as_str(), ast::StrStyle::Cooked)?;
                     s.popen()?;
                     s.print_expr(&inputs[in_idx])?;
                     s.pclose()?;
@@ -1535,7 +1536,7 @@ impl<'a> State<'a> {
                 self.word_space(":")?;
 
                 self.commasep(Inconsistent, &a.clobbers, |s, co| {
-                    s.print_string(&co, ast::StrStyle::Cooked)?;
+                    s.print_string(&co.as_str(), ast::StrStyle::Cooked)?;
                     Ok(())
                 })?;
 

src/librustc/infer/error_reporting.rs

@@ -91,8 +91,8 @@ use std::cell::{Cell, RefCell};
 use std::char::from_u32;
 use std::fmt;
 use syntax::ast;
-use syntax::parse::token;
 use syntax::ptr::P;
+use syntax::symbol::Symbol;
 use syntax_pos::{self, Pos, Span};
 use errors::DiagnosticBuilder;
 
@@ -1219,7 +1219,7 @@ impl<'a, 'gcx, 'tcx> Rebuilder<'a, 'gcx, 'tcx> {
                 names.push(lt_name);
             }
             names.sort();
-            let name = token::intern(&names[0]);
+            let name = Symbol::intern(&names[0]);
             return (name_to_dummy_lifetime(name), Kept);
         }
         return (self.life_giver.give_lifetime(), Fresh);
@@ -1931,7 +1931,7 @@ impl LifeGiver {
             let mut s = String::from("'");
             s.push_str(&num_to_string(self.counter.get()));
             if !self.taken.contains(&s) {
-                lifetime = name_to_dummy_lifetime(token::intern(&s[..]));
+                lifetime = name_to_dummy_lifetime(Symbol::intern(&s));
                 self.generated.borrow_mut().push(lifetime);
                 break;
             }

src/librustc/lint/context.rs

@@ -40,7 +40,6 @@ use std::default::Default as StdDefault;
 use std::mem;
 use std::fmt;
 use syntax::attr;
-use syntax::parse::token::InternedString;
 use syntax::ast;
 use syntax_pos::{MultiSpan, Span};
 use errors::{self, Diagnostic, DiagnosticBuilder};
@@ -384,8 +383,7 @@ macro_rules! run_lints { ($cx:expr, $f:ident, $ps:ident, $($args:expr),*) => ({
 /// Parse the lint attributes into a vector, with `Err`s for malformed lint
 /// attributes. Writing this as an iterator is an enormous mess.
 // See also the hir version just below.
-pub fn gather_attrs(attrs: &[ast::Attribute])
-                    -> Vec<Result<(InternedString, Level, Span), Span>> {
+pub fn gather_attrs(attrs: &[ast::Attribute]) -> Vec<Result<(ast::Name, Level, Span), Span>> {
     let mut out = vec![];
     for attr in attrs {
         let r = gather_attr(attr);
@@ -394,18 +392,17 @@ pub fn gather_attrs(attrs: &[ast::Attribute])
     out
 }
 
-pub fn gather_attr(attr: &ast::Attribute)
-                   -> Vec<Result<(InternedString, Level, Span), Span>> {
+pub fn gather_attr(attr: &ast::Attribute) -> Vec<Result<(ast::Name, Level, Span), Span>> {
     let mut out = vec![];
 
-    let level = match Level::from_str(&attr.name()) {
+    let level = match Level::from_str(&attr.name().as_str()) {
         None => return out,
         Some(lvl) => lvl,
     };
 
     attr::mark_used(attr);
 
-    let meta = &attr.node.value;
+    let meta = &attr.value;
     let metas = if let Some(metas) = meta.meta_item_list() {
         metas
     } else {
@@ -414,9 +411,7 @@ pub fn gather_attr(attr: &ast::Attribute)
     };
 
     for li in metas {
-        out.push(li.word().map_or(Err(li.span), |word| {
-            Ok((word.name().clone(), level, word.span))
-        }));
+        out.push(li.word().map_or(Err(li.span), |word| Ok((word.name(), level, word.span))));
     }
 
     out
@@ -629,10 +624,10 @@ pub trait LintContext: Sized {
                     continue;
                 }
                 Ok((lint_name, level, span)) => {
-                    match self.lints().find_lint(&lint_name, &self.sess(), Some(span)) {
+                    match self.lints().find_lint(&lint_name.as_str(), &self.sess(), Some(span)) {
                         Ok(lint_id) => vec![(lint_id, level, span)],
                         Err(FindLintError::NotFound) => {
-                            match self.lints().lint_groups.get(&lint_name[..]) {
+                            match self.lints().lint_groups.get(&*lint_name.as_str()) {
                                 Some(&(ref v, _)) => v.iter()
                                                       .map(|lint_id: &LintId|
                                                            (*lint_id, level, span))
@@ -1193,8 +1188,7 @@ fn check_lint_name_attribute(cx: &LateContext, attr: &ast::Attribute) {
                 continue;
             }
             Ok((lint_name, _, span)) => {
-                match check_lint_name(&cx.lints,
-                                      &lint_name[..]) {
+                match check_lint_name(&cx.lints, &lint_name.as_str()) {
                     CheckLintNameResult::Ok => (),
                     CheckLintNameResult::Warning(ref msg) => {
                         cx.span_lint(builtin::RENAMED_AND_REMOVED_LINTS,

src/librustc/middle/const_val.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use syntax::parse::token::InternedString;
+use syntax::symbol::InternedString;
 use syntax::ast;
 use std::rc::Rc;
 use hir::def_id::DefId;

src/librustc/middle/cstore.rs

@@ -39,7 +39,7 @@ use syntax::ast;
 use syntax::attr;
 use syntax::ext::base::SyntaxExtension;
 use syntax::ptr::P;
-use syntax::parse::token::InternedString;
+use syntax::symbol::Symbol;
 use syntax_pos::Span;
 use rustc_back::target::Target;
 use hir;
@@ -52,7 +52,7 @@ pub use self::NativeLibraryKind::{NativeStatic, NativeFramework, NativeUnknown};
 
 #[derive(Clone, Debug)]
 pub struct LinkMeta {
-    pub crate_name: String,
+    pub crate_name: Symbol,
     pub crate_hash: Svh,
 }
 
@@ -92,8 +92,8 @@ pub enum NativeLibraryKind {
 #[derive(Clone, Hash, RustcEncodable, RustcDecodable)]
 pub struct NativeLibrary {
     pub kind: NativeLibraryKind,
-    pub name: String,
-    pub cfg: Option<P<ast::MetaItem>>,
+    pub name: Symbol,
+    pub cfg: Option<ast::MetaItem>,
 }
 
 /// The data we save and restore about an inlined item or method.  This is not
@@ -205,11 +205,11 @@ pub trait CrateStore<'tcx> {
     fn extern_crate(&self, cnum: CrateNum) -> Option<ExternCrate>;
     /// The name of the crate as it is referred to in source code of the current
     /// crate.
-    fn crate_name(&self, cnum: CrateNum) -> InternedString;
+    fn crate_name(&self, cnum: CrateNum) -> Symbol;
     /// The name of the crate as it is stored in the crate's metadata.
-    fn original_crate_name(&self, cnum: CrateNum) -> InternedString;
+    fn original_crate_name(&self, cnum: CrateNum) -> Symbol;
     fn crate_hash(&self, cnum: CrateNum) -> Svh;
-    fn crate_disambiguator(&self, cnum: CrateNum) -> InternedString;
+    fn crate_disambiguator(&self, cnum: CrateNum) -> Symbol;
     fn plugin_registrar_fn(&self, cnum: CrateNum) -> Option<DefId>;
     fn native_libraries(&self, cnum: CrateNum) -> Vec<NativeLibrary>;
     fn reachable_ids(&self, cnum: CrateNum) -> Vec<DefId>;
@@ -375,13 +375,13 @@ impl<'tcx> CrateStore<'tcx> for DummyCrateStore {
         bug!("panic_strategy")
     }
     fn extern_crate(&self, cnum: CrateNum) -> Option<ExternCrate> { bug!("extern_crate") }
-    fn crate_name(&self, cnum: CrateNum) -> InternedString { bug!("crate_name") }
-    fn original_crate_name(&self, cnum: CrateNum) -> InternedString {
+    fn crate_name(&self, cnum: CrateNum) -> Symbol { bug!("crate_name") }
+    fn original_crate_name(&self, cnum: CrateNum) -> Symbol {
         bug!("original_crate_name")
     }
     fn crate_hash(&self, cnum: CrateNum) -> Svh { bug!("crate_hash") }
     fn crate_disambiguator(&self, cnum: CrateNum)
-                           -> InternedString { bug!("crate_disambiguator") }
+                           -> Symbol { bug!("crate_disambiguator") }
     fn plugin_registrar_fn(&self, cnum: CrateNum) -> Option<DefId>
         { bug!("plugin_registrar_fn") }
     fn native_libraries(&self, cnum: CrateNum) -> Vec<NativeLibrary>

src/librustc/middle/dead.rs

@@ -309,8 +309,7 @@ fn has_allow_dead_code_or_lang_attr(attrs: &[ast::Attribute]) -> bool {
     let dead_code = lint::builtin::DEAD_CODE.name_lower();
     for attr in lint::gather_attrs(attrs) {
         match attr {
-            Ok((ref name, lint::Allow, _))
-                if &name[..] == dead_code => return true,
+            Ok((name, lint::Allow, _)) if name == &*dead_code => return true,
             _ => (),
         }
     }
@@ -499,8 +498,7 @@ impl<'a, 'tcx> DeadVisitor<'a, 'tcx> {
                       span: syntax_pos::Span,
                       name: ast::Name,
                       node_type: &str) {
-        let name = name.as_str();
-        if !name.starts_with("_") {
+        if !name.as_str().starts_with("_") {
             self.tcx
                 .sess
                 .add_lint(lint::builtin::DEAD_CODE,

src/librustc/middle/entry.rs

@@ -92,7 +92,7 @@ fn entry_point_type(item: &Item, at_root: bool) -> EntryPointType {
                 EntryPointType::Start
             } else if attr::contains_name(&item.attrs, "main") {
                 EntryPointType::MainAttr
-            } else if item.name.as_str() == "main" {
+            } else if item.name == "main" {
                 if at_root {
                     // This is a top-level function so can be 'main'
                     EntryPointType::MainNamed

src/librustc/middle/intrinsicck.rs

@@ -55,7 +55,7 @@ impl<'a, 'gcx, 'tcx> ExprVisitor<'a, 'gcx, 'tcx> {
             ty::TyFnDef(.., ref bfty) => bfty.abi == RustIntrinsic,
             _ => return false
         };
-        intrinsic && self.infcx.tcx.item_name(def_id).as_str() == "transmute"
+        intrinsic && self.infcx.tcx.item_name(def_id) == "transmute"
     }
 
     fn check_transmute(&self, span: Span, from: Ty<'gcx>, to: Ty<'gcx>, id: ast::NodeId) {

src/librustc/middle/lang_items.rs

@@ -30,7 +30,7 @@ use middle::weak_lang_items;
 use util::nodemap::FxHashMap;
 
 use syntax::ast;
-use syntax::parse::token::InternedString;
+use syntax::symbol::Symbol;
 use hir::itemlikevisit::ItemLikeVisitor;
 use hir;
 
@@ -152,7 +152,7 @@ struct LanguageItemCollector<'a, 'tcx: 'a> {
 impl<'a, 'v, 'tcx> ItemLikeVisitor<'v> for LanguageItemCollector<'a, 'tcx> {
     fn visit_item(&mut self, item: &hir::Item) {
         if let Some(value) = extract(&item.attrs) {
-            let item_index = self.item_refs.get(&value[..]).cloned();
+            let item_index = self.item_refs.get(&*value.as_str()).cloned();
 
             if let Some(item_index) = item_index {
                 self.collect_item(item_index, self.ast_map.local_def_id(item.id))
@@ -160,7 +160,7 @@ impl<'a, 'v, 'tcx> ItemLikeVisitor<'v> for LanguageItemCollector<'a, 'tcx> {
                 let span = self.ast_map.span(item.id);
                 span_err!(self.session, span, E0522,
                           "definition of an unknown language item: `{}`.",
-                          &value[..]);
+                          value);
             }
         }
     }
@@ -243,12 +243,10 @@ impl<'a, 'tcx> LanguageItemCollector<'a, 'tcx> {
     }
 }
 
-pub fn extract(attrs: &[ast::Attribute]) -> Option<InternedString> {
+pub fn extract(attrs: &[ast::Attribute]) -> Option<Symbol> {
     for attribute in attrs {
         match attribute.value_str() {
-            Some(ref value) if attribute.check_name("lang") => {
-                return Some(value.clone());
-            }
+            Some(value) if attribute.check_name("lang") => return Some(value),
             _ => {}
         }
     }

src/librustc/middle/liveness.rs

@@ -123,8 +123,8 @@ use std::io::prelude::*;
 use std::io;
 use std::rc::Rc;
 use syntax::ast::{self, NodeId};
-use syntax::parse::token::keywords;
 use syntax::ptr::P;
+use syntax::symbol::keywords;
 use syntax_pos::Span;
 
 use hir::Expr;

src/librustc/middle/recursion_limit.rs

@@ -25,7 +25,7 @@ pub fn update_recursion_limit(sess: &Session, krate: &ast::Crate) {
         }
 
         if let Some(s) = attr.value_str() {
-            if let Some(n) = s.parse().ok() {
+            if let Some(n) = s.as_str().parse().ok() {
                 sess.recursion_limit.set(n);
                 return;
             }

src/librustc/middle/resolve_lifetime.rs

@@ -27,7 +27,7 @@ use middle::region;
 use ty;
 use std::mem::replace;
 use syntax::ast;
-use syntax::parse::token::keywords;
+use syntax::symbol::keywords;
 use syntax_pos::Span;
 use util::nodemap::NodeMap;
 

src/librustc/middle/stability.rs

@@ -21,7 +21,7 @@ use hir::def::Def;
 use hir::def_id::{CrateNum, CRATE_DEF_INDEX, DefId, DefIndex, LOCAL_CRATE};
 use ty::{self, TyCtxt, AdtKind};
 use middle::privacy::AccessLevels;
-use syntax::parse::token::InternedString;
+use syntax::symbol::Symbol;
 use syntax_pos::{Span, DUMMY_SP};
 use syntax::ast;
 use syntax::ast::{NodeId, Attribute};
@@ -36,7 +36,6 @@ use hir::pat_util::EnumerateAndAdjustIterator;
 
 use std::mem::replace;
 use std::cmp::Ordering;
-use std::ops::Deref;
 
 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Copy, Debug, Eq, Hash)]
 pub enum StabilityLevel {
@@ -151,10 +150,11 @@ impl<'a, 'tcx: 'a> Annotator<'a, 'tcx> {
 
                 // Check if deprecated_since < stable_since. If it is,
                 // this is *almost surely* an accident.
-                if let (&Some(attr::RustcDeprecation {since: ref dep_since, ..}),
-                        &attr::Stable {since: ref stab_since}) = (&stab.rustc_depr, &stab.level) {
+                if let (&Some(attr::RustcDeprecation {since: dep_since, ..}),
+                        &attr::Stable {since: stab_since}) = (&stab.rustc_depr, &stab.level) {
                     // Explicit version of iter::order::lt to handle parse errors properly
-                    for (dep_v, stab_v) in dep_since.split(".").zip(stab_since.split(".")) {
+                    for (dep_v, stab_v) in
+                            dep_since.as_str().split(".").zip(stab_since.as_str().split(".")) {
                         if let (Ok(dep_v), Ok(stab_v)) = (dep_v.parse::<u64>(), stab_v.parse()) {
                             match dep_v.cmp(&stab_v) {
                                 Ordering::Less => {
@@ -356,7 +356,7 @@ impl<'a, 'tcx> Index<'tcx> {
 /// features and possibly prints errors. Returns a list of all
 /// features used.
 pub fn check_unstable_api_usage<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>)
-                                          -> FxHashMap<InternedString, attr::StabilityLevel> {
+                                          -> FxHashMap<Symbol, attr::StabilityLevel> {
     let _task = tcx.dep_graph.in_task(DepNode::StabilityCheck);
     let ref active_lib_features = tcx.sess.features.borrow().declared_lib_features;
 
@@ -376,8 +376,8 @@ pub fn check_unstable_api_usage<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>)
 
 struct Checker<'a, 'tcx: 'a> {
     tcx: TyCtxt<'a, 'tcx, 'tcx>,
-    active_features: FxHashSet<InternedString>,
-    used_features: FxHashMap<InternedString, attr::StabilityLevel>,
+    active_features: FxHashSet<Symbol>,
+    used_features: FxHashMap<Symbol, attr::StabilityLevel>,
     // Within a block where feature gate checking can be skipped.
     in_skip_block: u32,
 }
@@ -407,10 +407,10 @@ impl<'a, 'tcx> Checker<'a, 'tcx> {
                 if !self.active_features.contains(feature) {
                     let msg = match *reason {
                         Some(ref r) => format!("use of unstable library feature '{}': {}",
-                                               &feature, &r),
+                                               &feature.as_str(), &r),
                         None => format!("use of unstable library feature '{}'", &feature)
                     };
-                    emit_feature_err(&self.tcx.sess.parse_sess, &feature, span,
+                    emit_feature_err(&self.tcx.sess.parse_sess, &feature.as_str(), span,
                                      GateIssue::Library(Some(issue)), &msg);
                 }
             }
@@ -455,7 +455,7 @@ impl<'a, 'tcx> Visitor<'tcx> for Checker<'a, 'tcx> {
         // When compiling with --test we don't enforce stability on the
         // compiler-generated test module, demarcated with `DUMMY_SP` plus the
         // name `__test`
-        if item.span == DUMMY_SP && item.name.as_str() == "__test" { return }
+        if item.span == DUMMY_SP && item.name == "__test" { return }
 
         check_item(self.tcx, item, true,
                    &mut |id, sp, stab, depr| self.check(id, sp, stab, depr));
@@ -735,10 +735,10 @@ impl<'a, 'tcx> TyCtxt<'a, 'tcx, 'tcx> {
 /// were expected to be library features), and the list of features used from
 /// libraries, identify activated features that don't exist and error about them.
 pub fn check_unused_or_stable_features(sess: &Session,
-                                       lib_features_used: &FxHashMap<InternedString,
+                                       lib_features_used: &FxHashMap<Symbol,
                                                                      attr::StabilityLevel>) {
     let ref declared_lib_features = sess.features.borrow().declared_lib_features;
-    let mut remaining_lib_features: FxHashMap<InternedString, Span>
+    let mut remaining_lib_features: FxHashMap<Symbol, Span>
         = declared_lib_features.clone().into_iter().collect();
 
     fn format_stable_since_msg(version: &str) -> String {
@@ -746,7 +746,7 @@ pub fn check_unused_or_stable_features(sess: &Session,
     }
 
     for &(ref stable_lang_feature, span) in &sess.features.borrow().declared_stable_lang_features {
-        let version = find_lang_feature_accepted_version(stable_lang_feature.deref())
+        let version = find_lang_feature_accepted_version(&stable_lang_feature.as_str())
             .expect("unexpectedly couldn't find version feature was stabilized");
         sess.add_lint(lint::builtin::STABLE_FEATURES,
                       ast::CRATE_NODE_ID,
@@ -761,7 +761,7 @@ pub fn check_unused_or_stable_features(sess: &Session,
                     sess.add_lint(lint::builtin::STABLE_FEATURES,
                                   ast::CRATE_NODE_ID,
                                   span,
-                                  format_stable_since_msg(version.deref()));
+                                  format_stable_since_msg(&version.as_str()));
                 }
             }
             None => ( /* used but undeclared, handled during the previous ast visit */ )

src/librustc/middle/weak_lang_items.rs

@@ -16,7 +16,7 @@ use middle::lang_items;
 
 use rustc_back::PanicStrategy;
 use syntax::ast;
-use syntax::parse::token::InternedString;
+use syntax::symbol::Symbol;
 use syntax_pos::Span;
 use hir::intravisit::Visitor;
 use hir::intravisit;
@@ -55,10 +55,10 @@ pub fn check_crate(krate: &hir::Crate,
     verify(sess, items);
 }
 
-pub fn link_name(attrs: &[ast::Attribute]) -> Option<InternedString> {
+pub fn link_name(attrs: &[ast::Attribute]) -> Option<Symbol> {
     lang_items::extract(attrs).and_then(|name| {
-        $(if &name[..] == stringify!($name) {
-            Some(InternedString::new(stringify!($sym)))
+        $(if name == stringify!($name) {
+            Some(Symbol::intern(stringify!($sym)))
         } else)* {
             None
         }
@@ -126,7 +126,7 @@ impl<'a> Context<'a> {
 impl<'a, 'v> Visitor<'v> for Context<'a> {
     fn visit_foreign_item(&mut self, i: &hir::ForeignItem) {
         if let Some(lang_item) = lang_items::extract(&i.attrs) {
-            self.register(&lang_item, i.span);
+            self.register(&lang_item.as_str(), i.span);
         }
         intravisit::walk_foreign_item(self, i)
     }

src/librustc/session/config.rs

@@ -25,9 +25,8 @@ use lint;
 use middle::cstore;
 
 use syntax::ast::{self, IntTy, UintTy};
-use syntax::attr;
 use syntax::parse;
-use syntax::parse::token::InternedString;
+use syntax::symbol::Symbol;
 use syntax::feature_gate::UnstableFeatures;
 
 use errors::{ColorConfig, FatalError, Handler};
@@ -41,6 +40,7 @@ use std::collections::btree_map::Values as BTreeMapValuesIter;
 use std::fmt;
 use std::hash::Hasher;
 use std::collections::hash_map::DefaultHasher;
+use std::collections::HashSet;
 use std::iter::FromIterator;
 use std::path::PathBuf;
 
@@ -927,8 +927,6 @@ pub fn default_lib_output() -> CrateType {
 }
 
 pub fn default_configuration(sess: &Session) -> ast::CrateConfig {
-    use syntax::parse::token::intern_and_get_ident as intern;
-
     let end = &sess.target.target.target_endian;
     let arch = &sess.target.target.arch;
     let wordsz = &sess.target.target.target_pointer_width;
@@ -938,55 +936,46 @@ pub fn default_configuration(sess: &Session) -> ast::CrateConfig {
     let max_atomic_width = sess.target.target.max_atomic_width();
 
     let fam = if let Some(ref fam) = sess.target.target.options.target_family {
-        intern(fam)
+        Symbol::intern(fam)
     } else if sess.target.target.options.is_like_windows {
-        InternedString::new("windows")
+        Symbol::intern("windows")
     } else {
-        InternedString::new("unix")
+        Symbol::intern("unix")
     };
 
-    let mk = attr::mk_name_value_item_str;
-    let mut ret = vec![ // Target bindings.
-        mk(InternedString::new("target_os"), intern(os)),
-        mk(InternedString::new("target_family"), fam.clone()),
-        mk(InternedString::new("target_arch"), intern(arch)),
-        mk(InternedString::new("target_endian"), intern(end)),
-        mk(InternedString::new("target_pointer_width"), intern(wordsz)),
-        mk(InternedString::new("target_env"), intern(env)),
-        mk(InternedString::new("target_vendor"), intern(vendor)),
-    ];
-    match &fam[..] {
-        "windows" | "unix" => ret.push(attr::mk_word_item(fam)),
-        _ => (),
+    let mut ret = HashSet::new();
+    // Target bindings.
+    ret.insert((Symbol::intern("target_os"), Some(Symbol::intern(os))));
+    ret.insert((Symbol::intern("target_family"), Some(fam)));
+    ret.insert((Symbol::intern("target_arch"), Some(Symbol::intern(arch))));
+    ret.insert((Symbol::intern("target_endian"), Some(Symbol::intern(end))));
+    ret.insert((Symbol::intern("target_pointer_width"), Some(Symbol::intern(wordsz))));
+    ret.insert((Symbol::intern("target_env"), Some(Symbol::intern(env))));
+    ret.insert((Symbol::intern("target_vendor"), Some(Symbol::intern(vendor))));
+    if fam == "windows" || fam == "unix" {
+        ret.insert((fam, None));
     }
     if sess.target.target.options.has_elf_tls {
-        ret.push(attr::mk_word_item(InternedString::new("target_thread_local")));
+        ret.insert((Symbol::intern("target_thread_local"), None));
     }
     for &i in &[8, 16, 32, 64, 128] {
         if i <= max_atomic_width {
             let s = i.to_string();
-            ret.push(mk(InternedString::new("target_has_atomic"), intern(&s)));
+            ret.insert((Symbol::intern("target_has_atomic"), Some(Symbol::intern(&s))));
             if &s == wordsz {
-                ret.push(mk(InternedString::new("target_has_atomic"), intern("ptr")));
+                ret.insert((Symbol::intern("target_has_atomic"), Some(Symbol::intern("ptr"))));
             }
         }
     }
     if sess.opts.debug_assertions {
-        ret.push(attr::mk_word_item(InternedString::new("debug_assertions")));
+        ret.insert((Symbol::intern("debug_assertions"), None));
     }
     if sess.opts.crate_types.contains(&CrateTypeProcMacro) {
-        ret.push(attr::mk_word_item(InternedString::new("proc_macro")));
+        ret.insert((Symbol::intern("proc_macro"), None));
     }
     return ret;
 }
 
-pub fn append_configuration(cfg: &mut ast::CrateConfig,
-                            name: InternedString) {
-    if !cfg.iter().any(|mi| mi.name() == name) {
-        cfg.push(attr::mk_word_item(name))
-    }
-}
-
 pub fn build_configuration(sess: &Session,
                            mut user_cfg: ast::CrateConfig)
                            -> ast::CrateConfig {
@@ -995,11 +984,10 @@ pub fn build_configuration(sess: &Session,
     let default_cfg = default_configuration(sess);
     // If the user wants a test runner, then add the test cfg
     if sess.opts.test {
-        append_configuration(&mut user_cfg, InternedString::new("test"))
+        user_cfg.insert((Symbol::intern("test"), None));
     }
-    let mut v = user_cfg.into_iter().collect::<Vec<_>>();
-    v.extend_from_slice(&default_cfg[..]);
-    v
+    user_cfg.extend(default_cfg.iter().cloned());
+    user_cfg
 }
 
 pub fn build_target_config(opts: &Options, sp: &Handler) -> Config {
@@ -1245,11 +1233,14 @@ pub fn parse_cfgspecs(cfgspecs: Vec<String> ) -> ast::CrateConfig {
         let meta_item = panictry!(parser.parse_meta_item());
 
         if !parser.reader.is_eof() {
-            early_error(ErrorOutputType::default(), &format!("invalid --cfg argument: {}",
-                                                             s))
+            early_error(ErrorOutputType::default(), &format!("invalid --cfg argument: {}", s))
+        } else if meta_item.is_meta_item_list() {
+            let msg =
+                format!("invalid predicate in --cfg command line argument: `{}`", meta_item.name());
+            early_error(ErrorOutputType::default(), &msg)
         }
 
-        meta_item
+        (meta_item.name(), meta_item.value_str())
     }).collect::<ast::CrateConfig>()
 }
 
@@ -1773,9 +1764,7 @@ mod tests {
     use std::rc::Rc;
     use super::{OutputType, OutputTypes, Externs};
     use rustc_back::PanicStrategy;
-    use syntax::{ast, attr};
-    use syntax::parse::token::InternedString;
-    use syntax::codemap::dummy_spanned;
+    use syntax::symbol::Symbol;
 
     fn optgroups() -> Vec<OptGroup> {
         super::rustc_optgroups().into_iter()
@@ -1804,9 +1793,7 @@ mod tests {
         let (sessopts, cfg) = build_session_options_and_crate_config(matches);
         let sess = build_session(sessopts, &dep_graph, None, registry, Rc::new(DummyCrateStore));
         let cfg = build_configuration(&sess, cfg);
-        assert!(attr::contains(&cfg, &dummy_spanned(ast::MetaItemKind::Word({
-            InternedString::new("test")
-        }))));
+        assert!(cfg.contains(&(Symbol::intern("test"), None)));
     }
 
     // When the user supplies --test and --cfg test, don't implicitly add
@@ -1827,7 +1814,7 @@ mod tests {
         let sess = build_session(sessopts, &dep_graph, None, registry,
                                  Rc::new(DummyCrateStore));
         let cfg = build_configuration(&sess, cfg);
-        let mut test_items = cfg.iter().filter(|m| m.name() == "test");
+        let mut test_items = cfg.iter().filter(|&&(name, _)| name == "test");
         assert!(test_items.next().is_some());
         assert!(test_items.next().is_none());
     }

src/librustc/session/mod.rs

@@ -28,7 +28,7 @@ use syntax::json::JsonEmitter;
 use syntax::feature_gate;
 use syntax::parse;
 use syntax::parse::ParseSess;
-use syntax::parse::token;
+use syntax::symbol::Symbol;
 use syntax::{ast, codemap};
 use syntax::feature_gate::AttributeType;
 use syntax_pos::{Span, MultiSpan};
@@ -89,7 +89,7 @@ pub struct Session {
     // forms a unique global identifier for the crate. It is used to allow
     // multiple crates with the same name to coexist. See the
     // trans::back::symbol_names module for more information.
-    pub crate_disambiguator: RefCell<token::InternedString>,
+    pub crate_disambiguator: RefCell<Symbol>,
     pub features: RefCell<feature_gate::Features>,
 
     /// The maximum recursion limit for potentially infinitely recursive
@@ -129,8 +129,8 @@ pub struct PerfStats {
 }
 
 impl Session {
-    pub fn local_crate_disambiguator(&self) -> token::InternedString {
-        self.crate_disambiguator.borrow().clone()
+    pub fn local_crate_disambiguator(&self) -> Symbol {
+        *self.crate_disambiguator.borrow()
     }
     pub fn struct_span_warn<'a, S: Into<MultiSpan>>(&'a self,
                                                     sp: S,
@@ -610,7 +610,7 @@ pub fn build_session_(sopts: config::Options,
         plugin_attributes: RefCell::new(Vec::new()),
         crate_types: RefCell::new(Vec::new()),
         dependency_formats: RefCell::new(FxHashMap()),
-        crate_disambiguator: RefCell::new(token::intern("").as_str()),
+        crate_disambiguator: RefCell::new(Symbol::intern("")),
         features: RefCell::new(feature_gate::Features::new()),
         recursion_limit: Cell::new(64),
         next_node_id: Cell::new(NodeId::new(1)),

src/librustc/traits/error_reporting.rs

@@ -246,12 +246,13 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                 let err_sp = item.meta().span.substitute_dummy(span);
                 let def = self.tcx.lookup_trait_def(trait_ref.def_id);
                 let trait_str = def.trait_ref.to_string();
-                if let Some(ref istring) = item.value_str() {
+                if let Some(istring) = item.value_str() {
+                    let istring = &*istring.as_str();
                     let generic_map = def.generics.types.iter().map(|param| {
                         (param.name.as_str().to_string(),
                          trait_ref.substs.type_for_def(param).to_string())
                     }).collect::<FxHashMap<String, String>>();
-                    let parser = Parser::new(&istring);
+                    let parser = Parser::new(istring);
                     let mut errored = false;
                     let err: String = parser.filter_map(|p| {
                         match p {

src/librustc/traits/project.rs

@@ -26,8 +26,8 @@ use super::util;
 use hir::def_id::DefId;
 use infer::InferOk;
 use rustc_data_structures::snapshot_map::{Snapshot, SnapshotMap};
-use syntax::parse::token;
 use syntax::ast;
+use syntax::symbol::Symbol;
 use ty::subst::Subst;
 use ty::{self, ToPredicate, ToPolyTraitRef, Ty, TyCtxt};
 use ty::fold::{TypeFoldable, TypeFolder};
@@ -1245,7 +1245,7 @@ fn confirm_callable_candidate<'cx, 'gcx, 'tcx>(
     let predicate = ty::Binder(ty::ProjectionPredicate { // (1) recreate binder here
         projection_ty: ty::ProjectionTy {
             trait_ref: trait_ref,
-            item_name: token::intern(FN_OUTPUT_NAME),
+            item_name: Symbol::intern(FN_OUTPUT_NAME),
         },
         ty: ret_type
     });

src/librustc/ty/context.rs

@@ -49,7 +49,7 @@ use std::rc::Rc;
 use std::iter;
 use syntax::ast::{self, Name, NodeId};
 use syntax::attr;
-use syntax::parse::token::{self, keywords};
+use syntax::symbol::{Symbol, keywords};
 
 use hir;
 
@@ -561,7 +561,7 @@ pub struct GlobalCtxt<'tcx> {
 
     /// The definite name of the current crate after taking into account
     /// attributes, commandline parameters, etc.
-    pub crate_name: token::InternedString,
+    pub crate_name: Symbol,
 
     /// Data layout specification for the current target.
     pub data_layout: TargetDataLayout,
@@ -574,7 +574,7 @@ pub struct GlobalCtxt<'tcx> {
 
     /// Map from function to the `#[derive]` mode that it's defining. Only used
     /// by `proc-macro` crates.
-    pub derive_macros: RefCell<NodeMap<token::InternedString>>,
+    pub derive_macros: RefCell<NodeMap<Symbol>>,
 }
 
 impl<'tcx> GlobalCtxt<'tcx> {
@@ -588,15 +588,15 @@ impl<'tcx> GlobalCtxt<'tcx> {
 }
 
 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
-    pub fn crate_name(self, cnum: CrateNum) -> token::InternedString {
+    pub fn crate_name(self, cnum: CrateNum) -> Symbol {
         if cnum == LOCAL_CRATE {
-            self.crate_name.clone()
+            self.crate_name
         } else {
             self.sess.cstore.crate_name(cnum)
         }
     }
 
-    pub fn original_crate_name(self, cnum: CrateNum) -> token::InternedString {
+    pub fn original_crate_name(self, cnum: CrateNum) -> Symbol {
         if cnum == LOCAL_CRATE {
             self.crate_name.clone()
         } else {
@@ -604,7 +604,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         }
     }
 
-    pub fn crate_disambiguator(self, cnum: CrateNum) -> token::InternedString {
+    pub fn crate_disambiguator(self, cnum: CrateNum) -> Symbol {
         if cnum == LOCAL_CRATE {
             self.sess.local_crate_disambiguator()
         } else {
@@ -835,7 +835,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             custom_coerce_unsized_kinds: RefCell::new(DefIdMap()),
             cast_kinds: RefCell::new(NodeMap()),
             fragment_infos: RefCell::new(DefIdMap()),
-            crate_name: token::intern_and_get_ident(crate_name),
+            crate_name: Symbol::intern(crate_name),
             data_layout: data_layout,
             layout_cache: RefCell::new(FxHashMap()),
             layout_depth: Cell::new(0),

src/librustc/ty/item_path.rs

@@ -12,7 +12,7 @@ use hir::map::DefPathData;
 use hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
 use ty::{self, Ty, TyCtxt};
 use syntax::ast;
-use syntax::parse::token;
+use syntax::symbol::Symbol;
 
 use std::cell::Cell;
 
@@ -94,14 +94,14 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                     if let Some(extern_crate_def_id) = opt_extern_crate {
                         self.push_item_path(buffer, extern_crate_def_id);
                     } else {
-                        buffer.push(&self.crate_name(cnum));
+                        buffer.push(&self.crate_name(cnum).as_str());
                     }
                 }
             }
             RootMode::Absolute => {
                 // In absolute mode, just write the crate name
                 // unconditionally.
-                buffer.push(&self.original_crate_name(cnum));
+                buffer.push(&self.original_crate_name(cnum).as_str());
             }
         }
     }
@@ -126,7 +126,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                         return true;
                     }
                     None => {
-                        buffer.push(&self.crate_name(cur_def.krate));
+                        buffer.push(&self.crate_name(cur_def.krate).as_str());
                         cur_path.iter().rev().map(|segment| buffer.push(&segment.as_str())).count();
                         return true;
                     }
@@ -136,7 +136,7 @@ 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(||
-                token::intern("<unnamed>")));
+                Symbol::intern("<unnamed>")));
             match visible_parent_map.get(&cur_def) {
                 Some(&def) => cur_def = def,
                 None => return false,

src/librustc/ty/mod.rs

@@ -44,7 +44,7 @@ use std::vec::IntoIter;
 use std::mem;
 use syntax::ast::{self, Name, NodeId};
 use syntax::attr;
-use syntax::parse::token::{self, InternedString};
+use syntax::symbol::{Symbol, InternedString};
 use syntax_pos::{DUMMY_SP, Span};
 
 use rustc_const_math::ConstInt;
@@ -2344,7 +2344,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         if let Some(id) = self.map.as_local_node_id(id) {
             self.map.name(id)
         } else if id.index == CRATE_DEF_INDEX {
-            token::intern(&self.sess.cstore.original_crate_name(id.krate))
+            self.sess.cstore.original_crate_name(id.krate)
         } else {
             let def_key = self.sess.cstore.def_key(id);
             // The name of a StructCtor is that of its struct parent.
@@ -2747,7 +2747,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 
     /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
     /// with the name of the crate containing the impl.
-    pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, InternedString> {
+    pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
         if impl_did.is_local() {
             let node_id = self.map.as_local_node_id(impl_did).unwrap();
             Ok(self.map.span(node_id))

src/librustc/ty/sty.rs

@@ -23,7 +23,7 @@ use std::fmt;
 use std::ops;
 use syntax::abi;
 use syntax::ast::{self, Name};
-use syntax::parse::token::{keywords, InternedString};
+use syntax::symbol::{keywords, InternedString};
 
 use serialize;
 

src/librustc/util/ppaux.rs

@@ -25,8 +25,8 @@ use std::fmt;
 use std::usize;
 
 use syntax::abi::Abi;
-use syntax::parse::token;
 use syntax::ast::CRATE_NODE_ID;
+use syntax::symbol::Symbol;
 use hir;
 
 pub fn verbose() -> bool {
@@ -284,7 +284,7 @@ fn in_binder<'a, 'gcx, 'tcx, T, U>(f: &mut fmt::Formatter,
             ty::BrAnon(_) |
             ty::BrFresh(_) |
             ty::BrEnv => {
-                let name = token::intern("'r");
+                let name = Symbol::intern("'r");
                 let _ = write!(f, "{}", name);
                 ty::BrNamed(tcx.map.local_def_id(CRATE_NODE_ID),
                             name,

src/librustc_borrowck/borrowck/mir/dataflow/sanity_check.rs

@@ -169,7 +169,7 @@ fn is_rustc_peek<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                 {
                     let name = tcx.item_name(def_id);
                     if abi == Abi::RustIntrinsic || abi == Abi::PlatformIntrinsic {
-                        if name.as_str() == "rustc_peek" {
+                        if name == "rustc_peek" {
                             return Some((args, source_info.span));
                         }
                     }

src/librustc_borrowck/borrowck/mir/mod.rs

@@ -11,7 +11,6 @@
 use borrowck::BorrowckCtxt;
 
 use syntax::ast::{self, MetaItem};
-use syntax::ptr::P;
 use syntax_pos::{Span, DUMMY_SP};
 
 use rustc::hir;
@@ -35,7 +34,7 @@ use self::dataflow::{MaybeInitializedLvals, MaybeUninitializedLvals};
 use self::dataflow::{DefinitelyInitializedLvals};
 use self::gather_moves::{MoveData, MovePathIndex, LookupResult};
 
-fn has_rustc_mir_with(attrs: &[ast::Attribute], name: &str) -> Option<P<MetaItem>> {
+fn has_rustc_mir_with(attrs: &[ast::Attribute], name: &str) -> Option<MetaItem> {
     for attr in attrs {
         if attr.check_name("rustc_mir") {
             let items = attr.meta_item_list();

src/librustc_const_eval/eval.rs

@@ -1221,7 +1221,7 @@ fn lit_to_const<'a, 'tcx>(lit: &ast::LitKind,
     use syntax::ast::*;
     use syntax::ast::LitIntType::*;
     match *lit {
-        LitKind::Str(ref s, _) => Ok(Str((*s).clone())),
+        LitKind::Str(ref s, _) => Ok(Str(s.as_str())),
         LitKind::ByteStr(ref data) => Ok(ByteStr(data.clone())),
         LitKind::Byte(n) => Ok(Integral(U8(n))),
         LitKind::Int(n, Signed(ity)) => {
@@ -1249,15 +1249,15 @@ fn lit_to_const<'a, 'tcx>(lit: &ast::LitKind,
             infer(Infer(n), tcx, &ty::TyUint(ity)).map(Integral)
         },
 
-        LitKind::Float(ref n, fty) => {
-            parse_float(n, Some(fty)).map(Float)
+        LitKind::Float(n, fty) => {
+            parse_float(&n.as_str(), Some(fty)).map(Float)
         }
-        LitKind::FloatUnsuffixed(ref n) => {
+        LitKind::FloatUnsuffixed(n) => {
             let fty_hint = match ty_hint.map(|t| &t.sty) {
                 Some(&ty::TyFloat(fty)) => Some(fty),
                 _ => None
             };
-            parse_float(n, fty_hint).map(Float)
+            parse_float(&n.as_str(), fty_hint).map(Float)
         }
         LitKind::Bool(b) => Ok(Bool(b)),
         LitKind::Char(c) => Ok(Char(c)),

src/librustc_driver/driver.rs

@@ -53,7 +53,8 @@ use std::path::{Path, PathBuf};
 use syntax::{ast, diagnostics, visit};
 use syntax::attr;
 use syntax::ext::base::ExtCtxt;
-use syntax::parse::{self, PResult, token};
+use syntax::parse::{self, PResult};
+use syntax::symbol::Symbol;
 use syntax::util::node_count::NodeCounter;
 use syntax;
 use syntax_ext;
@@ -210,9 +211,6 @@ pub fn compile_input(sess: &Session,
                 tcx.print_debug_stats();
             }
 
-            // Discard interned strings as they are no longer required.
-            token::clear_ident_interner();
-
             Ok((outputs, trans))
         })??
     };
@@ -563,8 +561,7 @@ pub fn phase_2_configure_and_expand<'a, F>(sess: &Session,
     *sess.features.borrow_mut() = features;
 
     *sess.crate_types.borrow_mut() = collect_crate_types(sess, &krate.attrs);
-    *sess.crate_disambiguator.borrow_mut() =
-        token::intern(&compute_crate_disambiguator(sess)).as_str();
+    *sess.crate_disambiguator.borrow_mut() = Symbol::intern(&compute_crate_disambiguator(sess));
 
     time(time_passes, "recursion limit", || {
         middle::recursion_limit::update_recursion_limit(sess, &krate);
@@ -1107,7 +1104,7 @@ pub fn phase_6_link_output(sess: &Session,
                            outputs: &OutputFilenames) {
     time(sess.time_passes(),
          "linking",
-         || link::link_binary(sess, trans, outputs, &trans.link.crate_name));
+         || link::link_binary(sess, trans, outputs, &trans.link.crate_name.as_str()));
 }
 
 fn escape_dep_filename(filename: &str) -> String {
@@ -1358,11 +1355,3 @@ pub fn build_output_filenames(input: &Input,
         }
     }
 }
-
-// For use by the `rusti` project (https://github.com/murarth/rusti).
-pub fn reset_thread_local_state() {
-    // These may be left in an incoherent state after a previous compile.
-    syntax::ext::hygiene::reset_hygiene_data();
-    // `clear_ident_interner` can be used to free memory, but it does not restore the initial state.
-    token::reset_ident_interner();
-}

src/librustc_driver/lib.rs

@@ -95,12 +95,11 @@ use std::str;
 use std::sync::{Arc, Mutex};
 use std::thread;
 
-use syntax::{ast, json};
+use syntax::ast;
 use syntax::codemap::{CodeMap, FileLoader, RealFileLoader};
 use syntax::feature_gate::{GatedCfg, UnstableFeatures};
 use syntax::parse::{self, PResult};
-use syntax_pos::MultiSpan;
-use errors::emitter::Emitter;
+use syntax_pos::{DUMMY_SP, MultiSpan};
 
 #[cfg(test)]
 pub mod test;
@@ -374,37 +373,11 @@ fn handle_explain(code: &str,
     }
 }
 
-fn check_cfg(cfg: &ast::CrateConfig,
-             output: ErrorOutputType) {
-    let emitter: Box<Emitter> = match output {
-        config::ErrorOutputType::HumanReadable(color_config) => {
-            Box::new(errors::emitter::EmitterWriter::stderr(color_config, None))
-        }
-        config::ErrorOutputType::Json => Box::new(json::JsonEmitter::basic()),
-    };
-    let handler = errors::Handler::with_emitter(true, false, emitter);
-
-    let mut saw_invalid_predicate = false;
-    for item in cfg.iter() {
-        if item.is_meta_item_list() {
-            saw_invalid_predicate = true;
-            handler.emit(&MultiSpan::new(),
-                         &format!("invalid predicate in --cfg command line argument: `{}`",
-                                  item.name()),
-                            errors::Level::Fatal);
-        }
-    }
-
-    if saw_invalid_predicate {
-        panic!(errors::FatalError);
-    }
-}
-
 impl<'a> CompilerCalls<'a> for RustcDefaultCalls {
     fn early_callback(&mut self,
                       matches: &getopts::Matches,
                       _: &config::Options,
-                      cfg: &ast::CrateConfig,
+                      _: &ast::CrateConfig,
                       descriptions: &errors::registry::Registry,
                       output: ErrorOutputType)
                       -> Compilation {
@@ -413,7 +386,6 @@ impl<'a> CompilerCalls<'a> for RustcDefaultCalls {
             return Compilation::Stop;
         }
 
-        check_cfg(cfg, output);
         Compilation::Continue
     }
 
@@ -640,24 +612,27 @@ impl RustcDefaultCalls {
                     let allow_unstable_cfg = UnstableFeatures::from_environment()
                         .is_nightly_build();
 
-                    for cfg in &sess.parse_sess.config {
-                        if !allow_unstable_cfg && GatedCfg::gate(cfg).is_some() {
+                    let mut cfgs = Vec::new();
+                    for &(name, ref value) in sess.parse_sess.config.iter() {
+                        let gated_cfg = GatedCfg::gate(&ast::MetaItem {
+                            name: name,
+                            node: ast::MetaItemKind::Word,
+                            span: DUMMY_SP,
+                        });
+                        if !allow_unstable_cfg && gated_cfg.is_some() {
                             continue;
                         }
 
-                        if cfg.is_word() {
-                            println!("{}", cfg.name());
-                        } else if let Some(s) = cfg.value_str() {
-                            println!("{}=\"{}\"", cfg.name(), s);
-                        } else if cfg.is_meta_item_list() {
-                            // Right now there are not and should not be any
-                            // MetaItemKind::List items in the configuration returned by
-                            // `build_configuration`.
-                            panic!("Found an unexpected list in cfg attribute '{}'!", cfg.name())
+                        cfgs.push(if let &Some(ref value) = value {
+                            format!("{}=\"{}\"", name, value)
                         } else {
-                            // There also shouldn't be literals.
-                            panic!("Found an unexpected literal in cfg attribute '{}'!", cfg.name())
-                        }
+                            format!("{}", name)
+                        });
+                    }
+
+                    cfgs.sort();
+                    for cfg in cfgs {
+                        println!("{}", cfg);
                     }
                 }
                 PrintRequest::TargetCPUs => {

src/librustc_driver/pretty.rs

@@ -450,15 +450,15 @@ impl<'ast> PrinterSupport<'ast> for HygieneAnnotation<'ast> {
 impl<'ast> pprust::PpAnn for HygieneAnnotation<'ast> {
     fn post(&self, s: &mut pprust::State, node: pprust::AnnNode) -> io::Result<()> {
         match node {
-            pprust::NodeIdent(&ast::Ident { name: ast::Name(nm), ctxt }) => {
+            pprust::NodeIdent(&ast::Ident { name, ctxt }) => {
                 pp::space(&mut s.s)?;
                 // FIXME #16420: this doesn't display the connections
                 // between syntax contexts
-                s.synth_comment(format!("{}{:?}", nm, ctxt))
+                s.synth_comment(format!("{}{:?}", name.as_u32(), ctxt))
             }
-            pprust::NodeName(&ast::Name(nm)) => {
+            pprust::NodeName(&name) => {
                 pp::space(&mut s.s)?;
-                s.synth_comment(nm.to_string())
+                s.synth_comment(name.as_u32().to_string())
             }
             _ => Ok(()),
         }

src/librustc_driver/target_features.rs

@@ -8,13 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use syntax::{ast, attr};
+use syntax::ast;
 use llvm::LLVMRustHasFeature;
 use rustc::session::Session;
 use rustc_trans::back::write::create_target_machine;
 use syntax::feature_gate::UnstableFeatures;
-use syntax::parse::token::InternedString;
-use syntax::parse::token::intern_and_get_ident as intern;
+use syntax::symbol::Symbol;
 use libc::c_char;
 
 // WARNING: the features must be known to LLVM or the feature
@@ -41,11 +40,11 @@ pub fn add_configuration(cfg: &mut ast::CrateConfig, sess: &Session) {
         _ => &[],
     };
 
-    let tf = InternedString::new("target_feature");
+    let tf = Symbol::intern("target_feature");
     for feat in whitelist {
         assert_eq!(feat.chars().last(), Some('\0'));
         if unsafe { LLVMRustHasFeature(target_machine, feat.as_ptr() as *const c_char) } {
-            cfg.push(attr::mk_name_value_item_str(tf.clone(), intern(&feat[..feat.len() - 1])))
+            cfg.insert((tf, Some(Symbol::intern(&feat[..feat.len() - 1]))));
         }
     }
 
@@ -74,6 +73,6 @@ pub fn add_configuration(cfg: &mut ast::CrateConfig, sess: &Session) {
     }
 
     if crt_static {
-        cfg.push(attr::mk_name_value_item_str(tf.clone(), intern("crt-static")));
+        cfg.insert((tf, Some(Symbol::intern("crt-static"))));
     }
 }

src/librustc_driver/test.rs

@@ -34,8 +34,8 @@ use syntax::codemap::CodeMap;
 use errors;
 use errors::emitter::Emitter;
 use errors::{Level, DiagnosticBuilder};
-use syntax::parse::token;
 use syntax::feature_gate::UnstableFeatures;
+use syntax::symbol::Symbol;
 
 use rustc::hir;
 
@@ -288,11 +288,11 @@ impl<'a, 'gcx, 'tcx> Env<'a, 'gcx, 'tcx> {
 
     pub fn t_param(&self, index: u32) -> Ty<'tcx> {
         let name = format!("T{}", index);
-        self.infcx.tcx.mk_param(index, token::intern(&name[..]))
+        self.infcx.tcx.mk_param(index, Symbol::intern(&name[..]))
     }
 
     pub fn re_early_bound(&self, index: u32, name: &'static str) -> &'tcx ty::Region {
-        let name = token::intern(name);
+        let name = Symbol::intern(name);
         self.infcx.tcx.mk_region(ty::ReEarlyBound(ty::EarlyBoundRegion {
             index: index,
             name: name,

src/librustc_incremental/assert_dep_graph.rs

@@ -57,7 +57,6 @@ use std::env;
 use std::fs::File;
 use std::io::Write;
 use syntax::ast;
-use syntax::parse::token::InternedString;
 use syntax_pos::Span;
 use {ATTR_IF_THIS_CHANGED, ATTR_THEN_THIS_WOULD_NEED};
 
@@ -97,7 +96,7 @@ pub fn assert_dep_graph<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
 }
 
 type Sources = Vec<(Span, DefId, DepNode<DefId>)>;
-type Targets = Vec<(Span, InternedString, ast::NodeId, DepNode<DefId>)>;
+type Targets = Vec<(Span, ast::Name, ast::NodeId, DepNode<DefId>)>;
 
 struct IfThisChanged<'a, 'tcx:'a> {
     tcx: TyCtxt<'a, 'tcx, 'tcx>,
@@ -106,7 +105,7 @@ struct IfThisChanged<'a, 'tcx:'a> {
 }
 
 impl<'a, 'tcx> IfThisChanged<'a, 'tcx> {
-    fn argument(&self, attr: &ast::Attribute) -> Option<InternedString> {
+    fn argument(&self, attr: &ast::Attribute) -> Option<ast::Name> {
         let mut value = None;
         for list_item in attr.meta_item_list().unwrap_or_default() {
             match list_item.word() {
@@ -127,8 +126,8 @@ impl<'a, 'tcx> IfThisChanged<'a, 'tcx> {
                 let dep_node_interned = self.argument(attr);
                 let dep_node = match dep_node_interned {
                     None => DepNode::Hir(def_id),
-                    Some(ref n) => {
-                        match DepNode::from_label_string(&n[..], def_id) {
+                    Some(n) => {
+                        match DepNode::from_label_string(&n.as_str(), def_id) {
                             Ok(n) => n,
                             Err(()) => {
                                 self.tcx.sess.span_fatal(
@@ -142,8 +141,8 @@ impl<'a, 'tcx> IfThisChanged<'a, 'tcx> {
             } else if attr.check_name(ATTR_THEN_THIS_WOULD_NEED) {
                 let dep_node_interned = self.argument(attr);
                 let dep_node = match dep_node_interned {
-                    Some(ref n) => {
-                        match DepNode::from_label_string(&n[..], def_id) {
+                    Some(n) => {
+                        match DepNode::from_label_string(&n.as_str(), def_id) {
                             Ok(n) => n,
                             Err(()) => {
                                 self.tcx.sess.span_fatal(
@@ -159,7 +158,7 @@ impl<'a, 'tcx> IfThisChanged<'a, 'tcx> {
                     }
                 };
                 self.then_this_would_need.push((attr.span,
-                                                dep_node_interned.clone().unwrap(),
+                                                dep_node_interned.unwrap(),
                                                 node_id,
                                                 dep_node));
             }

src/librustc_incremental/calculate_svh/mod.rs

@@ -172,8 +172,8 @@ impl<'a, 'tcx> HashItemsVisitor<'a, 'tcx> {
 
         let crate_disambiguator = self.tcx.sess.local_crate_disambiguator();
         "crate_disambiguator".hash(&mut crate_state);
-        crate_disambiguator.len().hash(&mut crate_state);
-        crate_disambiguator.hash(&mut crate_state);
+        crate_disambiguator.as_str().len().hash(&mut crate_state);
+        crate_disambiguator.as_str().hash(&mut crate_state);
 
         // add each item (in some deterministic order) to the overall
         // crate hash.

src/librustc_incremental/calculate_svh/svh_visitor.rs

@@ -18,6 +18,7 @@ use syntax::abi::Abi;
 use syntax::ast::{self, Name, NodeId};
 use syntax::attr;
 use syntax::parse::token;
+use syntax::symbol::{Symbol, InternedString};
 use syntax_pos::{Span, NO_EXPANSION, COMMAND_LINE_EXPN, BytePos};
 use syntax::tokenstream;
 use rustc::hir;
@@ -169,8 +170,8 @@ enum SawAbiComponent<'a> {
 
     // FIXME (#14132): should we include (some function of)
     // ident.ctxt as well?
-    SawIdent(token::InternedString),
-    SawStructDef(token::InternedString),
+    SawIdent(InternedString),
+    SawStructDef(InternedString),
 
     SawLifetime,
     SawLifetimeDef(usize),
@@ -232,11 +233,11 @@ enum SawAbiComponent<'a> {
 #[derive(Hash)]
 enum SawExprComponent<'a> {
 
-    SawExprLoop(Option<token::InternedString>),
-    SawExprField(token::InternedString),
+    SawExprLoop(Option<InternedString>),
+    SawExprField(InternedString),
     SawExprTupField(usize),
-    SawExprBreak(Option<token::InternedString>),
-    SawExprAgain(Option<token::InternedString>),
+    SawExprBreak(Option<InternedString>),
+    SawExprAgain(Option<InternedString>),
 
     SawExprBox,
     SawExprArray,
@@ -246,6 +247,8 @@ enum SawExprComponent<'a> {
     SawExprBinary(hir::BinOp_),
     SawExprUnary(hir::UnOp),
     SawExprLit(ast::LitKind),
+    SawExprLitStr(InternedString, ast::StrStyle),
+    SawExprLitFloat(InternedString, Option<ast::FloatTy>),
     SawExprCast,
     SawExprType,
     SawExprIf,
@@ -314,7 +317,7 @@ fn saw_expr<'a>(node: &'a Expr_,
         ExprUnary(op, _)         => {
             (SawExprUnary(op), unop_can_panic_at_runtime(op))
         }
-        ExprLit(ref lit)         => (SawExprLit(lit.node.clone()), false),
+        ExprLit(ref lit)         => (saw_lit(lit), false),
         ExprCast(..)             => (SawExprCast, false),
         ExprType(..)             => (SawExprType, false),
         ExprIf(..)               => (SawExprIf, false),
@@ -341,6 +344,15 @@ fn saw_expr<'a>(node: &'a Expr_,
     }
 }
 
+fn saw_lit(lit: &ast::Lit) -> SawExprComponent<'static> {
+    match lit.node {
+        ast::LitKind::Str(s, style) => SawExprLitStr(s.as_str(), style),
+        ast::LitKind::Float(s, ty) => SawExprLitFloat(s.as_str(), Some(ty)),
+        ast::LitKind::FloatUnsuffixed(s) => SawExprLitFloat(s.as_str(), None),
+        ref node @ _ => SawExprLit(node.clone()),
+    }
+}
+
 #[derive(Hash)]
 enum SawItemComponent {
     SawItemExternCrate,
@@ -874,22 +886,16 @@ impl<'a, 'hash, 'tcx> StrictVersionHashVisitor<'a, 'hash, 'tcx> {
 
         // ignoring span information, it doesn't matter here
         self.hash_discriminant(&meta_item.node);
+        meta_item.name.as_str().len().hash(self.st);
+        meta_item.name.as_str().hash(self.st);
+
         match meta_item.node {
-            ast::MetaItemKind::Word(ref s) => {
-                s.len().hash(self.st);
-                s.hash(self.st);
-            }
-            ast::MetaItemKind::NameValue(ref s, ref lit) => {
-                s.len().hash(self.st);
-                s.hash(self.st);
-                lit.node.hash(self.st);
-            }
-            ast::MetaItemKind::List(ref s, ref items) => {
-                s.len().hash(self.st);
-                s.hash(self.st);
+            ast::MetaItemKind::Word => {}
+            ast::MetaItemKind::NameValue(ref lit) => saw_lit(lit).hash(self.st),
+            ast::MetaItemKind::List(ref items) => {
                 // Sort subitems so the hash does not depend on their order
                 let indices = self.indices_sorted_by(&items, |p| {
-                    (p.name(), fnv::hash(&p.literal().map(|i| &i.node)))
+                    (p.name().map(Symbol::as_str), fnv::hash(&p.literal().map(saw_lit)))
                 });
                 items.len().hash(self.st);
                 for (index, &item_index) in indices.iter().enumerate() {
@@ -901,7 +907,7 @@ impl<'a, 'hash, 'tcx> StrictVersionHashVisitor<'a, 'hash, 'tcx> {
                             self.hash_meta_item(meta_item);
                         }
                         ast::NestedMetaItemKind::Literal(ref lit) => {
-                            lit.node.hash(self.st);
+                            saw_lit(lit).hash(self.st);
                         }
                     }
                 }
@@ -914,11 +920,11 @@ impl<'a, 'hash, 'tcx> StrictVersionHashVisitor<'a, 'hash, 'tcx> {
         let indices = self.indices_sorted_by(attributes, |attr| attr.name());
 
         for i in indices {
-            let attr = &attributes[i].node;
+            let attr = &attributes[i];
             if !attr.is_sugared_doc &&
-               !IGNORED_ATTRIBUTES.contains(&&*attr.value.name()) {
+               !IGNORED_ATTRIBUTES.contains(&&*attr.value.name().as_str()) {
                 SawAttribute(attr.style).hash(self.st);
-                self.hash_meta_item(&*attr.value);
+                self.hash_meta_item(&attr.value);
             }
         }
     }

src/librustc_incremental/persist/directory.rs

@@ -84,8 +84,8 @@ impl DefIdDirectory {
             assert_eq!(old_info.krate, krate);
             let old_name: &str = &old_info.name;
             let old_disambiguator: &str = &old_info.disambiguator;
-            let new_name: &str = &tcx.crate_name(krate);
-            let new_disambiguator: &str = &tcx.crate_disambiguator(krate);
+            let new_name: &str = &tcx.crate_name(krate).as_str();
+            let new_disambiguator: &str = &tcx.crate_disambiguator(krate).as_str();
             old_name == new_name && old_disambiguator == new_disambiguator
         }
     }
@@ -99,8 +99,8 @@ impl DefIdDirectory {
         let new_krates: HashMap<_, _> =
             once(LOCAL_CRATE)
             .chain(tcx.sess.cstore.crates())
-            .map(|krate| (make_key(&tcx.crate_name(krate),
-                                   &tcx.crate_disambiguator(krate)), krate))
+            .map(|krate| (make_key(&tcx.crate_name(krate).as_str(),
+                                   &tcx.crate_disambiguator(krate).as_str()), krate))
             .collect();
 
         let ids = self.paths.iter()

src/librustc_incremental/persist/dirty_clean.rs

@@ -48,7 +48,6 @@ use rustc::hir::def_id::DefId;
 use rustc::hir::itemlikevisit::ItemLikeVisitor;
 use syntax::ast::{self, Attribute, NestedMetaItem};
 use rustc_data_structures::fx::{FxHashSet, FxHashMap};
-use syntax::parse::token::InternedString;
 use syntax_pos::Span;
 use rustc::ty::TyCtxt;
 use ich::Fingerprint;
@@ -88,12 +87,11 @@ pub struct DirtyCleanVisitor<'a, 'tcx:'a> {
 }
 
 impl<'a, 'tcx> DirtyCleanVisitor<'a, 'tcx> {
-
     fn dep_node(&self, attr: &Attribute, def_id: DefId) -> DepNode<DefId> {
         for item in attr.meta_item_list().unwrap_or(&[]) {
             if item.check_name(LABEL) {
                 let value = expect_associated_value(self.tcx, item);
-                match DepNode::from_label_string(&value[..], def_id) {
+                match DepNode::from_label_string(&value.as_str(), def_id) {
                     Ok(def_id) => return def_id,
                     Err(()) => {
                         self.tcx.sess.span_fatal(
@@ -276,13 +274,7 @@ fn check_config(tcx: TyCtxt, attr: &ast::Attribute) -> bool {
         if item.check_name(CFG) {
             let value = expect_associated_value(tcx, item);
             debug!("check_config: searching for cfg {:?}", value);
-            for cfg in &config[..] {
-                if cfg.check_name(&value[..]) {
-                    debug!("check_config: matched {:?}", cfg);
-                    return true;
-                }
-            }
-            return false;
+            return config.contains(&(value, None));
         }
     }
 
@@ -291,7 +283,7 @@ fn check_config(tcx: TyCtxt, attr: &ast::Attribute) -> bool {
         &format!("no cfg attribute"));
 }
 
-fn expect_associated_value(tcx: TyCtxt, item: &NestedMetaItem) -> InternedString {
+fn expect_associated_value(tcx: TyCtxt, item: &NestedMetaItem) -> ast::Name {
     if let Some(value) = item.value_str() {
         value
     } else {

src/librustc_incremental/persist/fs.rs

@@ -604,7 +604,7 @@ fn string_to_timestamp(s: &str) -> Result<SystemTime, ()> {
 }
 
 fn crate_path_tcx(tcx: TyCtxt, cnum: CrateNum) -> PathBuf {
-    crate_path(tcx.sess, &tcx.crate_name(cnum), &tcx.crate_disambiguator(cnum))
+    crate_path(tcx.sess, &tcx.crate_name(cnum).as_str(), &tcx.crate_disambiguator(cnum).as_str())
 }
 
 /// Finds the session directory containing the correct metadata hashes file for

src/librustc_lint/bad_style.rs

@@ -81,19 +81,12 @@ impl NonCamelCaseTypes {
                 .concat()
         }
 
-        let s = name.as_str();
-
         if !is_camel_case(name) {
-            let c = to_camel_case(&s);
+            let c = to_camel_case(&name.as_str());
             let m = if c.is_empty() {
-                format!("{} `{}` should have a camel case name such as `CamelCase`",
-                        sort,
-                        s)
+                format!("{} `{}` should have a camel case name such as `CamelCase`", sort, name)
             } else {
-                format!("{} `{}` should have a camel case name such as `{}`",
-                        sort,
-                        s,
-                        c)
+                format!("{} `{}` should have a camel case name such as `{}`", sort, name, c)
             };
             cx.span_lint(NON_CAMEL_CASE_TYPES, span, &m[..]);
         }
@@ -241,8 +234,8 @@ impl LateLintPass for NonSnakeCase {
             .and_then(|at| at.value_str().map(|s| (at, s)));
         if let Some(ref name) = cx.tcx.sess.opts.crate_name {
             self.check_snake_case(cx, "crate", name, None);
-        } else if let Some((attr, ref name)) = attr_crate_name {
-            self.check_snake_case(cx, "crate", name, Some(attr.span));
+        } else if let Some((attr, name)) = attr_crate_name {
+            self.check_snake_case(cx, "crate", &name.as_str(), Some(attr.span));
         }
     }
 
@@ -326,21 +319,19 @@ pub struct NonUpperCaseGlobals;
 
 impl NonUpperCaseGlobals {
     fn check_upper_case(cx: &LateContext, sort: &str, name: ast::Name, span: Span) {
-        let s = name.as_str();
-
-        if s.chars().any(|c| c.is_lowercase()) {
-            let uc = NonSnakeCase::to_snake_case(&s).to_uppercase();
-            if uc != &s[..] {
+        if name.as_str().chars().any(|c| c.is_lowercase()) {
+            let uc = NonSnakeCase::to_snake_case(&name.as_str()).to_uppercase();
+            if name != &*uc {
                 cx.span_lint(NON_UPPER_CASE_GLOBALS,
                              span,
                              &format!("{} `{}` should have an upper case name such as `{}`",
                                       sort,
-                                      s,
+                                      name,
                                       uc));
             } else {
                 cx.span_lint(NON_UPPER_CASE_GLOBALS,
                              span,
-                             &format!("{} `{}` should have an upper case name", sort, s));
+                             &format!("{} `{}` should have an upper case name", sort, name));
             }
         }
     }

src/librustc_lint/builtin.rs

@@ -45,6 +45,7 @@ use std::collections::HashSet;
 use syntax::ast;
 use syntax::attr;
 use syntax::feature_gate::{AttributeGate, AttributeType, Stability, deprecated_attributes};
+use syntax::symbol::Symbol;
 use syntax_pos::Span;
 
 use rustc::hir::{self, PatKind};
@@ -633,9 +634,9 @@ impl Deprecated {
             stability: &Option<&attr::Stability>,
             deprecation: &Option<stability::DeprecationEntry>) {
         // Deprecated attributes apply in-crate and cross-crate.
-        if let Some(&attr::Stability{rustc_depr: Some(attr::RustcDeprecation{ref reason, ..}), ..})
+        if let Some(&attr::Stability{rustc_depr: Some(attr::RustcDeprecation{reason, ..}), ..})
                 = *stability {
-            output(cx, DEPRECATED, span, Some(&reason))
+            output(cx, DEPRECATED, span, Some(reason))
         } else if let Some(ref depr_entry) = *deprecation {
             if let Some(parent_depr) = cx.tcx.lookup_deprecation_entry(self.parent_def(cx)) {
                 if parent_depr.same_origin(depr_entry) {
@@ -643,10 +644,10 @@ impl Deprecated {
                 }
             }
 
-            output(cx, DEPRECATED, span, depr_entry.attr.note.as_ref().map(|x| &**x))
+            output(cx, DEPRECATED, span, depr_entry.attr.note)
         }
 
-        fn output(cx: &LateContext, lint: &'static Lint, span: Span, note: Option<&str>) {
+        fn output(cx: &LateContext, lint: &'static Lint, span: Span, note: Option<Symbol>) {
             let msg = if let Some(note) = note {
                 format!("use of deprecated item: {}", note)
             } else {
@@ -772,9 +773,9 @@ impl LintPass for DeprecatedAttr {
 
 impl EarlyLintPass for DeprecatedAttr {
     fn check_attribute(&mut self, cx: &EarlyContext, attr: &ast::Attribute) {
-        let name = &*attr.name();
+        let name = attr.name();
         for &&(n, _, ref g) in &self.depr_attrs {
-            if n == name {
+            if name == n {
                 if let &AttributeGate::Gated(Stability::Deprecated(link),
                                              ref name,
                                              ref reason,
@@ -1228,7 +1229,7 @@ impl LateLintPass for MutableTransmutes {
                 ty::TyFnDef(.., ref bfty) if bfty.abi == RustIntrinsic => (),
                 _ => return false,
             }
-            cx.tcx.item_name(def_id).as_str() == "transmute"
+            cx.tcx.item_name(def_id) == "transmute"
         }
     }
 }

src/librustc_lint/types.rs

@@ -219,9 +219,9 @@ impl LateLintPass for TypeLimits {
                     ty::TyFloat(t) => {
                         let (min, max) = float_ty_range(t);
                         let lit_val: f64 = match lit.node {
-                            ast::LitKind::Float(ref v, _) |
-                            ast::LitKind::FloatUnsuffixed(ref v) => {
-                                match v.parse() {
+                            ast::LitKind::Float(v, _) |
+                            ast::LitKind::FloatUnsuffixed(v) => {
+                                match v.as_str().parse() {
                                     Ok(f) => f,
                                     Err(_) => return,
                                 }

src/librustc_lint/unused.rs

@@ -20,7 +20,7 @@ use std::collections::hash_map::Entry::{Occupied, Vacant};
 use syntax::ast;
 use syntax::attr;
 use syntax::feature_gate::{BUILTIN_ATTRIBUTES, AttributeType};
-use syntax::parse::token::keywords;
+use syntax::symbol::keywords;
 use syntax::ptr::P;
 use syntax_pos::Span;
 
@@ -48,7 +48,7 @@ impl UnusedMut {
                 let name = path1.node;
                 if let hir::BindByValue(hir::MutMutable) = mode {
                     if !name.as_str().starts_with("_") {
-                        match mutables.entry(name.0 as usize) {
+                        match mutables.entry(name) {
                             Vacant(entry) => {
                                 entry.insert(vec![id]);
                             }
@@ -162,7 +162,7 @@ impl LateLintPass for UnusedResults {
                     // check for #[must_use="..."]
                     if let Some(s) = attr.value_str() {
                         msg.push_str(": ");
-                        msg.push_str(&s);
+                        msg.push_str(&s.as_str());
                     }
                     cx.span_lint(UNUSED_MUST_USE, sp, &msg);
                     return true;
@@ -274,10 +274,10 @@ impl LateLintPass for UnusedAttributes {
             // Has a plugin registered this attribute as one which must be used at
             // the crate level?
             let plugin_crate = plugin_attributes.iter()
-                .find(|&&(ref x, t)| &*attr.name() == x && AttributeType::CrateLevel == t)
+                .find(|&&(ref x, t)| attr.name() == &**x && AttributeType::CrateLevel == t)
                 .is_some();
             if known_crate || plugin_crate {
-                let msg = match attr.node.style {
+                let msg = match attr.style {
                     ast::AttrStyle::Outer => {
                         "crate-level attribute should be an inner attribute: add an exclamation \
                          mark: #![foo]"

src/librustc_metadata/creader.rs

@@ -37,7 +37,7 @@ use syntax::abi::Abi;
 use syntax::attr;
 use syntax::ext::base::SyntaxExtension;
 use syntax::feature_gate::{self, GateIssue};
-use syntax::parse::token::{InternedString, intern};
+use syntax::symbol::Symbol;
 use syntax_pos::{Span, DUMMY_SP};
 use log;
 
@@ -52,7 +52,7 @@ pub struct CrateLoader<'a> {
     cstore: &'a CStore,
     next_crate_num: CrateNum,
     foreign_item_map: FxHashMap<String, Vec<ast::NodeId>>,
-    local_crate_name: String,
+    local_crate_name: Symbol,
 }
 
 fn dump_crates(cstore: &CStore) {
@@ -70,8 +70,8 @@ fn dump_crates(cstore: &CStore) {
 
 #[derive(Debug)]
 struct ExternCrateInfo {
-    ident: String,
-    name: String,
+    ident: Symbol,
+    name: Symbol,
     id: ast::NodeId,
     dep_kind: DepKind,
 }
@@ -80,7 +80,7 @@ fn register_native_lib(sess: &Session,
                        cstore: &CStore,
                        span: Option<Span>,
                        lib: NativeLibrary) {
-    if lib.name.is_empty() {
+    if lib.name.as_str().is_empty() {
         match span {
             Some(span) => {
                 struct_span_err!(sess, span, E0454,
@@ -147,7 +147,7 @@ impl<'a> CrateLoader<'a> {
             cstore: cstore,
             next_crate_num: cstore.next_crate_num(),
             foreign_item_map: FxHashMap(),
-            local_crate_name: local_crate_name.to_owned(),
+            local_crate_name: Symbol::intern(local_crate_name),
         }
     }
 
@@ -160,12 +160,12 @@ impl<'a> CrateLoader<'a> {
                     Some(name) => {
                         validate_crate_name(Some(self.sess), &name.as_str(),
                                             Some(i.span));
-                        name.to_string()
+                        name
                     }
-                    None => i.ident.to_string(),
+                    None => i.ident.name,
                 };
                 Some(ExternCrateInfo {
-                    ident: i.ident.to_string(),
+                    ident: i.ident.name,
                     name: name,
                     id: i.id,
                     dep_kind: if attr::contains_name(&i.attrs, "no_link") {
@@ -179,7 +179,7 @@ impl<'a> CrateLoader<'a> {
         }
     }
 
-    fn existing_match(&self, name: &str, hash: Option<&Svh>, kind: PathKind)
+    fn existing_match(&self, name: Symbol, hash: Option<&Svh>, kind: PathKind)
                       -> Option<CrateNum> {
         let mut ret = None;
         self.cstore.iter_crate_data(|cnum, data| {
@@ -201,7 +201,7 @@ impl<'a> CrateLoader<'a> {
             // `source` stores paths which are normalized which may be different
             // from the strings on the command line.
             let source = self.cstore.used_crate_source(cnum);
-            if let Some(locs) = self.sess.opts.externs.get(name) {
+            if let Some(locs) = self.sess.opts.externs.get(&*name.as_str()) {
                 let found = locs.iter().any(|l| {
                     let l = fs::canonicalize(l).ok();
                     source.dylib.as_ref().map(|p| &p.0) == l.as_ref() ||
@@ -233,7 +233,7 @@ impl<'a> CrateLoader<'a> {
                                   root: &CrateRoot) {
         // Check for (potential) conflicts with the local crate
         if self.local_crate_name == root.name &&
-           self.sess.local_crate_disambiguator() == &root.disambiguator[..] {
+           self.sess.local_crate_disambiguator() == root.disambiguator {
             span_fatal!(self.sess, span, E0519,
                         "the current crate is indistinguishable from one of its \
                          dependencies: it has the same crate-name `{}` and was \
@@ -258,8 +258,8 @@ impl<'a> CrateLoader<'a> {
 
     fn register_crate(&mut self,
                       root: &Option<CratePaths>,
-                      ident: &str,
-                      name: &str,
+                      ident: Symbol,
+                      name: Symbol,
                       span: Span,
                       lib: Library,
                       dep_kind: DepKind)
@@ -290,7 +290,7 @@ impl<'a> CrateLoader<'a> {
         let cnum_map = self.resolve_crate_deps(root, &crate_root, &metadata, cnum, span, dep_kind);
 
         let cmeta = Rc::new(cstore::CrateMetadata {
-            name: name.to_string(),
+            name: name,
             extern_crate: Cell::new(None),
             key_map: metadata.load_key_map(crate_root.index),
             proc_macros: crate_root.macro_derive_registrar.map(|_| {
@@ -314,8 +314,8 @@ impl<'a> CrateLoader<'a> {
 
     fn resolve_crate(&mut self,
                      root: &Option<CratePaths>,
-                     ident: &str,
-                     name: &str,
+                     ident: Symbol,
+                     name: Symbol,
                      hash: Option<&Svh>,
                      span: Span,
                      path_kind: PathKind,
@@ -459,13 +459,12 @@ impl<'a> CrateLoader<'a> {
         let deps = crate_root.crate_deps.decode(metadata);
         let map: FxHashMap<_, _> = deps.enumerate().map(|(crate_num, dep)| {
             debug!("resolving dep crate {} hash: `{}`", dep.name, dep.hash);
-            let dep_name = &dep.name.as_str();
             let dep_kind = match dep_kind {
                 DepKind::MacrosOnly => DepKind::MacrosOnly,
                 _ => dep.kind,
             };
             let (local_cnum, ..) = self.resolve_crate(
-                root, dep_name, dep_name, Some(&dep.hash), span, PathKind::Dependency, dep_kind,
+                root, dep.name, dep.name, Some(&dep.hash), span, PathKind::Dependency, dep_kind,
             );
             (CrateNum::new(crate_num + 1), local_cnum)
         }).collect();
@@ -485,13 +484,11 @@ impl<'a> CrateLoader<'a> {
         let target_triple = &self.sess.opts.target_triple[..];
         let is_cross = target_triple != config::host_triple();
         let mut target_only = false;
-        let ident = info.ident.clone();
-        let name = info.name.clone();
         let mut locate_ctxt = locator::Context {
             sess: self.sess,
             span: span,
-            ident: &ident[..],
-            crate_name: &name[..],
+            ident: info.ident,
+            crate_name: info.name,
             hash: None,
             filesearch: self.sess.host_filesearch(PathKind::Crate),
             target: &self.sess.host,
@@ -585,11 +582,11 @@ impl<'a> CrateLoader<'a> {
                                       trait_name: &str,
                                       expand: fn(TokenStream) -> TokenStream,
                                       attributes: &[&'static str]) {
-                let attrs = attributes.iter().map(|s| InternedString::new(s)).collect();
+                let attrs = attributes.iter().cloned().map(Symbol::intern).collect();
                 let derive = SyntaxExtension::CustomDerive(
                     Box::new(CustomDerive::new(expand, attrs))
                 );
-                self.0.push((intern(trait_name), Rc::new(derive)));
+                self.0.push((Symbol::intern(trait_name), Rc::new(derive)));
             }
         }
 
@@ -607,8 +604,8 @@ impl<'a> CrateLoader<'a> {
     pub fn find_plugin_registrar(&mut self, span: Span, name: &str)
                                  -> Option<(PathBuf, Svh, DefIndex)> {
         let ekrate = self.read_extension_crate(span, &ExternCrateInfo {
-             name: name.to_string(),
-             ident: name.to_string(),
+             name: Symbol::intern(name),
+             ident: Symbol::intern(name),
              id: ast::DUMMY_NODE_ID,
              dep_kind: DepKind::MacrosOnly,
         });
@@ -645,7 +642,7 @@ impl<'a> CrateLoader<'a> {
         let libs = self.cstore.get_used_libraries();
         for (foreign_lib, list) in self.foreign_item_map.iter() {
             let is_static = libs.borrow().iter().any(|lib| {
-                *foreign_lib == lib.name && lib.kind == cstore::NativeStatic
+                lib.name == &**foreign_lib && lib.kind == cstore::NativeStatic
             });
             if is_static {
                 for id in list {
@@ -708,8 +705,8 @@ impl<'a> CrateLoader<'a> {
         // in terms of everyone has a compatible panic runtime format, that's
         // performed later as part of the `dependency_format` module.
         let name = match desired_strategy {
-            PanicStrategy::Unwind => "panic_unwind",
-            PanicStrategy::Abort => "panic_abort",
+            PanicStrategy::Unwind => Symbol::intern("panic_unwind"),
+            PanicStrategy::Abort => Symbol::intern("panic_abort"),
         };
         info!("panic runtime not found -- loading {}", name);
 
@@ -791,9 +788,9 @@ impl<'a> CrateLoader<'a> {
         // * Staticlibs and Rust dylibs use system malloc
         // * Rust dylibs used as dependencies to rust use jemalloc
         let name = if need_lib_alloc && !self.sess.opts.cg.prefer_dynamic {
-            &self.sess.target.target.options.lib_allocation_crate
+            Symbol::intern(&self.sess.target.target.options.lib_allocation_crate)
         } else {
-            &self.sess.target.target.options.exe_allocation_crate
+            Symbol::intern(&self.sess.target.target.options.exe_allocation_crate)
         };
         let dep_kind = DepKind::Implicit;
         let (cnum, data) =
@@ -855,8 +852,8 @@ impl<'a> CrateLoader<'a> {
 impl<'a> CrateLoader<'a> {
     pub fn preprocess(&mut self, krate: &ast::Crate) {
         for attr in krate.attrs.iter().filter(|m| m.name() == "link_args") {
-            if let Some(ref linkarg) = attr.value_str() {
-                self.cstore.add_used_link_args(&linkarg);
+            if let Some(linkarg) = attr.value_str() {
+                self.cstore.add_used_link_args(&linkarg.as_str());
             }
         }
     }
@@ -869,7 +866,7 @@ impl<'a> CrateLoader<'a> {
         // First, add all of the custom #[link_args] attributes
         for m in i.attrs.iter().filter(|a| a.check_name("link_args")) {
             if let Some(linkarg) = m.value_str() {
-                self.cstore.add_used_link_args(&linkarg);
+                self.cstore.add_used_link_args(&linkarg.as_str());
             }
         }
 
@@ -881,7 +878,7 @@ impl<'a> CrateLoader<'a> {
             };
             let kind = items.iter().find(|k| {
                 k.check_name("kind")
-            }).and_then(|a| a.value_str());
+            }).and_then(|a| a.value_str()).map(Symbol::as_str);
             let kind = match kind.as_ref().map(|s| &s[..]) {
                 Some("static") => cstore::NativeStatic,
                 Some("dylib") => cstore::NativeUnknown,
@@ -903,7 +900,7 @@ impl<'a> CrateLoader<'a> {
                     struct_span_err!(self.sess, m.span, E0459,
                                      "#[link(...)] specified without `name = \"foo\"`")
                         .span_label(m.span, &format!("missing `name` argument")).emit();
-                    InternedString::new("foo")
+                    Symbol::intern("foo")
                 }
             };
             let cfg = items.iter().find(|k| {
@@ -913,7 +910,7 @@ impl<'a> CrateLoader<'a> {
                 list[0].meta_item().unwrap().clone()
             });
             let lib = NativeLibrary {
-                name: n.to_string(),
+                name: n,
                 kind: kind,
                 cfg: cfg,
             };
@@ -944,7 +941,7 @@ impl<'a> middle::cstore::CrateLoader for CrateLoader<'a> {
 
         for &(ref name, kind) in &self.sess.opts.libs {
             let lib = NativeLibrary {
-                name: name.clone(),
+                name: Symbol::intern(name),
                 kind: kind,
                 cfg: None,
             };
@@ -962,7 +959,7 @@ impl<'a> middle::cstore::CrateLoader for CrateLoader<'a> {
 
         let info = self.extract_crate_info(item).unwrap();
         let (cnum, ..) = self.resolve_crate(
-            &None, &info.ident, &info.name, None, item.span, PathKind::Crate, info.dep_kind,
+            &None, info.ident, info.name, None, item.span, PathKind::Crate, info.dep_kind,
         );
 
         let def_id = definitions.opt_local_def_id(item.id).unwrap();

src/librustc_metadata/cstore.rs

@@ -29,6 +29,7 @@ use std::path::PathBuf;
 use flate::Bytes;
 use syntax::{ast, attr};
 use syntax::ext::base::SyntaxExtension;
+use syntax::symbol::Symbol;
 use syntax_pos;
 
 pub use rustc::middle::cstore::{NativeLibrary, LinkagePreference};
@@ -58,7 +59,7 @@ pub struct ImportedFileMap {
 }
 
 pub struct CrateMetadata {
-    pub name: String,
+    pub name: Symbol,
 
     /// Information about the extern crate that caused this crate to
     /// be loaded. If this is `None`, then the crate was injected
@@ -213,7 +214,7 @@ impl CStore {
     }
 
     pub fn add_used_library(&self, lib: NativeLibrary) {
-        assert!(!lib.name.is_empty());
+        assert!(!lib.name.as_str().is_empty());
         self.used_libraries.borrow_mut().push(lib);
     }
 
@@ -249,14 +250,14 @@ impl CStore {
 }
 
 impl CrateMetadata {
-    pub fn name(&self) -> &str {
-        &self.root.name
+    pub fn name(&self) -> Symbol {
+        self.root.name
     }
     pub fn hash(&self) -> Svh {
         self.root.hash
     }
-    pub fn disambiguator(&self) -> &str {
-        &self.root.disambiguator
+    pub fn disambiguator(&self) -> Symbol {
+        self.root.disambiguator
     }
 
     pub fn is_staged_api(&self) -> bool {

src/librustc_metadata/cstore_impl.rs

@@ -31,7 +31,8 @@ use rustc_back::PanicStrategy;
 use std::path::PathBuf;
 use syntax::ast;
 use syntax::attr;
-use syntax::parse::{token, new_parser_from_source_str};
+use syntax::parse::new_parser_from_source_str;
+use syntax::symbol::Symbol;
 use syntax_pos::mk_sp;
 use rustc::hir::svh::Svh;
 use rustc_back::target::Target;
@@ -262,14 +263,14 @@ impl<'tcx> CrateStore<'tcx> for cstore::CStore {
         self.get_crate_data(cnum).panic_strategy()
     }
 
-    fn crate_name(&self, cnum: CrateNum) -> token::InternedString
+    fn crate_name(&self, cnum: CrateNum) -> Symbol
     {
-        token::intern_and_get_ident(&self.get_crate_data(cnum).name[..])
+        self.get_crate_data(cnum).name
     }
 
-    fn original_crate_name(&self, cnum: CrateNum) -> token::InternedString
+    fn original_crate_name(&self, cnum: CrateNum) -> Symbol
     {
-        token::intern_and_get_ident(&self.get_crate_data(cnum).name())
+        self.get_crate_data(cnum).name()
     }
 
     fn extern_crate(&self, cnum: CrateNum) -> Option<ExternCrate>
@@ -282,9 +283,9 @@ impl<'tcx> CrateStore<'tcx> for cstore::CStore {
         self.get_crate_hash(cnum)
     }
 
-    fn crate_disambiguator(&self, cnum: CrateNum) -> token::InternedString
+    fn crate_disambiguator(&self, cnum: CrateNum) -> Symbol
     {
-        token::intern_and_get_ident(&self.get_crate_data(cnum).disambiguator())
+        self.get_crate_data(cnum).disambiguator()
     }
 
     fn plugin_registrar_fn(&self, cnum: CrateNum) -> Option<DefId>

src/librustc_metadata/decoder.rs

@@ -934,7 +934,7 @@ impl<'a, 'tcx> CrateMetadata {
             .decode(self)
             .map(|mut attr| {
                 // Need new unique IDs: old thread-local IDs won't map to new threads.
-                attr.node.id = attr::mk_attr_id();
+                attr.id = attr::mk_attr_id();
                 attr
             })
             .collect()

src/librustc_metadata/encoder.rs

@@ -34,7 +34,7 @@ use std::rc::Rc;
 use std::u32;
 use syntax::ast::{self, CRATE_NODE_ID};
 use syntax::attr;
-use syntax;
+use syntax::symbol::Symbol;
 use syntax_pos;
 
 use rustc::hir::{self, PatKind};
@@ -600,7 +600,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             if let PatKind::Binding(_, ref path1, _) = arg.pat.node {
                 path1.node
             } else {
-                syntax::parse::token::intern("")
+                Symbol::intern("")
             }
         }))
     }
@@ -1119,7 +1119,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         let deps = get_ordered_deps(self.cstore);
         self.lazy_seq(deps.iter().map(|&(_, ref dep)| {
             CrateDep {
-                name: syntax::parse::token::intern(dep.name()),
+                name: dep.name(),
                 hash: dep.hash(),
                 kind: dep.dep_kind.get(),
             }
@@ -1279,10 +1279,10 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         let is_proc_macro = tcx.sess.crate_types.borrow().contains(&CrateTypeProcMacro);
         let root = self.lazy(&CrateRoot {
             rustc_version: rustc_version(),
-            name: link_meta.crate_name.clone(),
+            name: link_meta.crate_name,
             triple: tcx.sess.opts.target_triple.clone(),
             hash: link_meta.crate_hash,
-            disambiguator: tcx.sess.local_crate_disambiguator().to_string(),
+            disambiguator: tcx.sess.local_crate_disambiguator(),
             panic_strategy: tcx.sess.panic_strategy(),
             plugin_registrar_fn: tcx.sess
                 .plugin_registrar_fn

src/librustc_metadata/locator.rs

@@ -227,6 +227,7 @@ use rustc_llvm as llvm;
 use rustc_llvm::{False, ObjectFile, mk_section_iter};
 use rustc_llvm::archive_ro::ArchiveRO;
 use errors::DiagnosticBuilder;
+use syntax::symbol::Symbol;
 use syntax_pos::Span;
 use rustc_back::target::Target;
 
@@ -249,8 +250,8 @@ pub struct CrateMismatch {
 pub struct Context<'a> {
     pub sess: &'a Session,
     pub span: Span,
-    pub ident: &'a str,
-    pub crate_name: &'a str,
+    pub ident: Symbol,
+    pub crate_name: Symbol,
     pub hash: Option<&'a Svh>,
     // points to either self.sess.target.target or self.sess.host, must match triple
     pub target: &'a Target,
@@ -422,7 +423,7 @@ impl<'a> Context<'a> {
         // must be loaded via -L plus some filtering.
         if self.hash.is_none() {
             self.should_match_name = false;
-            if let Some(s) = self.sess.opts.externs.get(self.crate_name) {
+            if let Some(s) = self.sess.opts.externs.get(&self.crate_name.as_str()) {
                 return self.find_commandline_library(s.iter());
             }
             self.should_match_name = true;
@@ -533,7 +534,7 @@ impl<'a> Context<'a> {
                     if let Some((ref p, _)) = lib.rlib {
                         err.note(&format!("path: {}", p.display()));
                     }
-                    note_crate_name(&mut err, &lib.metadata.get_root().name);
+                    note_crate_name(&mut err, &lib.metadata.get_root().name.as_str());
                 }
                 err.emit();
                 None

src/librustc_metadata/schema.rs

@@ -22,6 +22,7 @@ use rustc_back::PanicStrategy;
 
 use rustc_serialize as serialize;
 use syntax::{ast, attr};
+use syntax::symbol::Symbol;
 use syntax_pos::{self, Span};
 
 use std::marker::PhantomData;
@@ -163,10 +164,10 @@ pub enum LazyState {
 #[derive(RustcEncodable, RustcDecodable)]
 pub struct CrateRoot {
     pub rustc_version: String,
-    pub name: String,
+    pub name: Symbol,
     pub triple: String,
     pub hash: hir::svh::Svh,
-    pub disambiguator: String,
+    pub disambiguator: Symbol,
     pub panic_strategy: PanicStrategy,
     pub plugin_registrar_fn: Option<DefIndex>,
     pub macro_derive_registrar: Option<DefIndex>,

src/librustc_mir/build/mod.rs

@@ -18,7 +18,7 @@ use rustc::util::nodemap::NodeMap;
 use rustc::hir;
 use syntax::abi::Abi;
 use syntax::ast;
-use syntax::parse::token::keywords;
+use syntax::symbol::keywords;
 use syntax_pos::Span;
 
 use rustc_data_structures::indexed_vec::{IndexVec, Idx};

src/librustc_mir/hair/cx/mod.rs

@@ -28,7 +28,7 @@ use rustc::hir::map::blocks::FnLikeNode;
 use rustc::infer::InferCtxt;
 use rustc::ty::subst::Subst;
 use rustc::ty::{self, Ty, TyCtxt};
-use syntax::parse::token;
+use syntax::symbol::{Symbol, InternedString};
 use rustc::hir;
 use rustc_const_math::{ConstInt, ConstUsize};
 
@@ -120,7 +120,7 @@ impl<'a, 'gcx, 'tcx> Cx<'a, 'gcx, 'tcx> {
         self.tcx.mk_nil()
     }
 
-    pub fn str_literal(&mut self, value: token::InternedString) -> Literal<'tcx> {
+    pub fn str_literal(&mut self, value: InternedString) -> Literal<'tcx> {
         Literal::Value { value: ConstVal::Str(value) }
     }
 
@@ -144,7 +144,7 @@ impl<'a, 'gcx, 'tcx> Cx<'a, 'gcx, 'tcx> {
                         self_ty: Ty<'tcx>,
                         params: &[Ty<'tcx>])
                         -> (Ty<'tcx>, Literal<'tcx>) {
-        let method_name = token::intern(method_name);
+        let method_name = Symbol::intern(method_name);
         let substs = self.tcx.mk_substs_trait(self_ty, params);
         for item in self.tcx.associated_items(trait_def_id) {
             if item.kind == ty::AssociatedKind::Method && item.name == method_name {

src/librustc_passes/ast_validation.rs

@@ -21,7 +21,8 @@ use rustc::session::Session;
 use syntax::ast::*;
 use syntax::attr;
 use syntax::codemap::Spanned;
-use syntax::parse::token::{self, keywords};
+use syntax::parse::token;
+use syntax::symbol::keywords;
 use syntax::visit::{self, Visitor};
 use syntax_pos::Span;
 use errors;
@@ -39,7 +40,7 @@ impl<'a> AstValidator<'a> {
         if label.name == keywords::StaticLifetime.name() {
             self.err_handler().span_err(span, &format!("invalid label name `{}`", label.name));
         }
-        if label.name.as_str() == "'_" {
+        if label.name == "'_" {
             self.session.add_lint(lint::builtin::LIFETIME_UNDERSCORE,
                                   id,
                                   span,
@@ -89,7 +90,7 @@ impl<'a> AstValidator<'a> {
 
 impl<'a> Visitor for AstValidator<'a> {
     fn visit_lifetime(&mut self, lt: &Lifetime) {
-        if lt.name.as_str() == "'_" {
+        if lt.name == "'_" {
             self.session.add_lint(lint::builtin::LIFETIME_UNDERSCORE,
                                   lt.id,
                                   lt.span,

src/librustc_passes/hir_stats.rs

@@ -240,7 +240,7 @@ impl<'v> hir_visit::Visitor<'v> for StatCollector<'v> {
         hir_visit::walk_assoc_type_binding(self, type_binding)
     }
     fn visit_attribute(&mut self, attr: &'v ast::Attribute) {
-        self.record("Attribute", Id::Attr(attr.node.id), attr);
+        self.record("Attribute", Id::Attr(attr.id), attr);
     }
     fn visit_macro_def(&mut self, macro_def: &'v hir::MacroDef) {
         self.record("MacroDef", Id::Node(macro_def.id), macro_def);

src/librustc_plugin/load.rs

@@ -69,9 +69,9 @@ pub fn load_plugins(sess: &Session,
             for plugin in plugins {
                 // plugins must have a name and can't be key = value
                 match plugin.name() {
-                    Some(ref name) if !plugin.is_value_str() => {
+                    Some(name) if !plugin.is_value_str() => {
                         let args = plugin.meta_item_list().map(ToOwned::to_owned);
-                        loader.load_plugin(plugin.span, name, args.unwrap_or_default());
+                        loader.load_plugin(plugin.span, &name.as_str(), args.unwrap_or_default());
                     },
                     _ => call_malformed_plugin_attribute(sess, attr.span),
                 }

src/librustc_plugin/registry.rs

@@ -17,7 +17,7 @@ use rustc::mir::transform::MirMapPass;
 
 use syntax::ext::base::{SyntaxExtension, NamedSyntaxExtension, NormalTT, IdentTT};
 use syntax::ext::base::MacroExpanderFn;
-use syntax::parse::token;
+use syntax::symbol::Symbol;
 use syntax::ast;
 use syntax::feature_gate::AttributeType;
 use syntax_pos::Span;
@@ -101,7 +101,7 @@ impl<'a> Registry<'a> {
     ///
     /// This is the most general hook into `libsyntax`'s expansion behavior.
     pub fn register_syntax_extension(&mut self, name: ast::Name, extension: SyntaxExtension) {
-        if name.as_str() == "macro_rules" {
+        if name == "macro_rules" {
             panic!("user-defined macros may not be named `macro_rules`");
         }
         self.syntax_exts.push((name, match extension {
@@ -121,7 +121,7 @@ impl<'a> Registry<'a> {
     /// It builds for you a `NormalTT` that calls `expander`,
     /// and also takes care of interning the macro's name.
     pub fn register_macro(&mut self, name: &str, expander: MacroExpanderFn) {
-        self.register_syntax_extension(token::intern(name),
+        self.register_syntax_extension(Symbol::intern(name),
                                        NormalTT(Box::new(expander), None, false));
     }
 

src/librustc_resolve/build_reduced_graph.rs

@@ -31,7 +31,6 @@ use std::rc::Rc;
 
 use syntax::ast::Name;
 use syntax::attr;
-use syntax::parse::token;
 
 use syntax::ast::{self, Block, ForeignItem, ForeignItemKind, Item, ItemKind};
 use syntax::ast::{Mutability, StmtKind, TraitItem, TraitItemKind};
@@ -41,7 +40,7 @@ use syntax::ext::base::Determinacy::Undetermined;
 use syntax::ext::expand::mark_tts;
 use syntax::ext::hygiene::Mark;
 use syntax::ext::tt::macro_rules;
-use syntax::parse::token::keywords;
+use syntax::symbol::keywords;
 use syntax::visit::{self, Visitor};
 
 use syntax_pos::{Span, DUMMY_SP};
@@ -139,7 +138,7 @@ impl<'b> Resolver<'b> {
                 match view_path.node {
                     ViewPathSimple(binding, ref full_path) => {
                         let mut source = full_path.segments.last().unwrap().identifier;
-                        let source_name = source.name.as_str();
+                        let source_name = source.name;
                         if source_name == "mod" || source_name == "self" {
                             resolve_error(self,
                                           view_path.span,
@@ -607,7 +606,7 @@ impl<'b> Resolver<'b> {
             if attr.check_name("macro_escape") {
                 let msg = "macro_escape is a deprecated synonym for macro_use";
                 let mut err = self.session.struct_span_warn(attr.span, msg);
-                if let ast::AttrStyle::Inner = attr.node.style {
+                if let ast::AttrStyle::Inner = attr.style {
                     err.help("consider an outer attribute, #[macro_use] mod ...").emit();
                 } else {
                     err.emit();
@@ -632,7 +631,7 @@ impl<'b> Resolver<'b> {
                 match attr.meta_item_list() {
                     Some(names) => for attr in names {
                         if let Some(word) = attr.word() {
-                            imports.imports.push((token::intern(&word.name()), attr.span()));
+                            imports.imports.push((word.name(), attr.span()));
                         } else {
                             span_err!(self.session, attr.span(), E0466, "bad macro import");
                         }
@@ -646,7 +645,7 @@ impl<'b> Resolver<'b> {
                 if let Some(names) = attr.meta_item_list() {
                     for attr in names {
                         if let Some(word) = attr.word() {
-                            imports.reexports.push((token::intern(&word.name()), attr.span()));
+                            imports.reexports.push((word.name(), attr.span()));
                         } else {
                             bad_macro_reexport(self, attr.span());
                         }

src/librustc_resolve/lib.rs

@@ -57,7 +57,7 @@ use syntax::ext::hygiene::{Mark, SyntaxContext};
 use syntax::ast::{self, FloatTy};
 use syntax::ast::{CRATE_NODE_ID, Name, NodeId, Ident, SpannedIdent, IntTy, UintTy};
 use syntax::ext::base::SyntaxExtension;
-use syntax::parse::token::{self, keywords};
+use syntax::symbol::{Symbol, keywords};
 use syntax::util::lev_distance::find_best_match_for_name;
 
 use syntax::visit::{self, FnKind, Visitor};
@@ -90,7 +90,7 @@ mod resolve_imports;
 
 enum SuggestionType {
     Macro(String),
-    Function(token::InternedString),
+    Function(Symbol),
     NotFound,
 }
 
@@ -1039,7 +1039,7 @@ impl PrimitiveTypeTable {
     }
 
     fn intern(&mut self, string: &str, primitive_type: PrimTy) {
-        self.primitive_types.insert(token::intern(string), primitive_type);
+        self.primitive_types.insert(Symbol::intern(string), primitive_type);
     }
 }
 
@@ -1460,7 +1460,6 @@ impl<'a> Resolver<'a> {
             let name = module_path[index].name;
             match self.resolve_name_in_module(search_module, name, TypeNS, false, span) {
                 Failed(_) => {
-                    let segment_name = name.as_str();
                     let module_name = module_to_string(search_module);
                     let msg = if "???" == &module_name {
                         let current_module = self.current_module;
@@ -1478,10 +1477,10 @@ impl<'a> Resolver<'a> {
 
                                 format!("Did you mean `{}{}`?", prefix, path_str)
                             }
-                            None => format!("Maybe a missing `extern crate {};`?", segment_name),
+                            None => format!("Maybe a missing `extern crate {};`?", name),
                         }
                     } else {
-                        format!("Could not find `{}` in `{}`", segment_name, module_name)
+                        format!("Could not find `{}` in `{}`", name, module_name)
                     };
 
                     return Failed(span.map(|span| (span, msg)));
@@ -1649,7 +1648,7 @@ impl<'a> Resolver<'a> {
     /// grammar: (SELF MOD_SEP ) ? (SUPER MOD_SEP) *
     fn resolve_module_prefix(&mut self, module_path: &[Ident], span: Option<Span>)
                              -> ResolveResult<ModulePrefixResult<'a>> {
-        if &*module_path[0].name.as_str() == "$crate" {
+        if module_path[0].name == "$crate" {
             return Success(PrefixFound(self.resolve_crate_var(module_path[0].ctxt), 1));
         }
 
@@ -1665,7 +1664,7 @@ impl<'a> Resolver<'a> {
             self.module_map[&self.current_module.normal_ancestor_id.unwrap()];
 
         // Now loop through all the `super`s we find.
-        while i < module_path.len() && "super" == module_path[i].name.as_str() {
+        while i < module_path.len() && module_path[i].name == "super" {
             debug!("(resolving module prefix) resolving `super` at {}",
                    module_to_string(&containing_module));
             if let Some(parent) = containing_module.parent {
@@ -2633,7 +2632,7 @@ impl<'a> Resolver<'a> {
         let qualified_binding = self.resolve_module_relative_path(span, segments, namespace);
         match (qualified_binding, unqualified_def) {
             (Ok(binding), Some(ref ud)) if binding.def() == ud.def &&
-                                           segments[0].identifier.name.as_str() != "$crate" => {
+                                           segments[0].identifier.name != "$crate" => {
                 self.session
                     .add_lint(lint::builtin::UNUSED_QUALIFICATIONS,
                               id,
@@ -2879,7 +2878,7 @@ impl<'a> Resolver<'a> {
     }
 
     fn find_best_match(&mut self, name: &str) -> SuggestionType {
-        if let Some(macro_name) = self.macro_names.iter().find(|n| n.as_str() == name) {
+        if let Some(macro_name) = self.macro_names.iter().find(|&n| n == &name) {
             return SuggestionType::Macro(format!("{}!", macro_name));
         }
 
@@ -2889,7 +2888,7 @@ impl<'a> Resolver<'a> {
                     .flat_map(|rib| rib.bindings.keys().map(|ident| &ident.name));
 
         if let Some(found) = find_best_match_for_name(names, name, None) {
-            if name != found {
+            if found != name {
                 return SuggestionType::Function(found);
             }
         } SuggestionType::NotFound
@@ -2998,8 +2997,7 @@ impl<'a> Resolver<'a> {
                                 false // Stop advancing
                             });
 
-                            if method_scope &&
-                                    &path_name[..] == keywords::SelfValue.name().as_str() {
+                            if method_scope && keywords::SelfValue.name() == &*path_name {
                                 resolve_error(self,
                                               expr.span,
                                               ResolutionError::SelfNotAvailableInStaticMethod);
@@ -3604,7 +3602,7 @@ fn module_to_string(module: Module) -> String {
             }
         } else {
             // danger, shouldn't be ident?
-            names.push(token::str_to_ident("<opaque>"));
+            names.push(Ident::from_str("<opaque>"));
             collect_mod(names, module.parent.unwrap());
         }
     }

src/librustc_resolve/macros.rs

@@ -27,7 +27,6 @@ use syntax::ext::expand::Expansion;
 use syntax::ext::hygiene::Mark;
 use syntax::ext::tt::macro_rules;
 use syntax::fold::Folder;
-use syntax::parse::token::intern;
 use syntax::ptr::P;
 use syntax::util::lev_distance::find_best_match_for_name;
 use syntax::visit::Visitor;
@@ -116,7 +115,7 @@ impl<'a> base::Resolver for Resolver<'a> {
         impl<'a, 'b> Folder for EliminateCrateVar<'a, 'b> {
             fn fold_path(&mut self, mut path: ast::Path) -> ast::Path {
                 let ident = path.segments[0].identifier;
-                if &ident.name.as_str() == "$crate" {
+                if ident.name == "$crate" {
                     path.global = true;
                     let module = self.0.resolve_crate_var(ident.ctxt);
                     if module.is_local() {
@@ -152,7 +151,7 @@ impl<'a> base::Resolver for Resolver<'a> {
     }
 
     fn add_macro(&mut self, scope: Mark, mut def: ast::MacroDef, export: bool) {
-        if &def.ident.name.as_str() == "macro_rules" {
+        if def.ident.name == "macro_rules" {
             self.session.span_err(def.span, "user-defined macros may not be named `macro_rules`");
         }
 
@@ -207,8 +206,7 @@ impl<'a> base::Resolver for Resolver<'a> {
 
     fn find_attr_invoc(&mut self, attrs: &mut Vec<ast::Attribute>) -> Option<ast::Attribute> {
         for i in 0..attrs.len() {
-            let name = intern(&attrs[i].name());
-            match self.builtin_macros.get(&name).cloned() {
+            match self.builtin_macros.get(&attrs[i].name()).cloned() {
                 Some(binding) => match *self.get_macro(binding) {
                     MultiModifier(..) | MultiDecorator(..) | SyntaxExtension::AttrProcMacro(..) => {
                         return Some(attrs.remove(i))

src/librustc_save_analysis/dump_visitor.rs

@@ -39,7 +39,8 @@ use std::collections::hash_map::DefaultHasher;
 use std::hash::*;
 
 use syntax::ast::{self, NodeId, PatKind, Attribute, CRATE_NODE_ID};
-use syntax::parse::token::{self, keywords};
+use syntax::parse::token;
+use syntax::symbol::keywords;
 use syntax::visit::{self, Visitor};
 use syntax::print::pprust::{path_to_string, ty_to_string, bounds_to_string, generics_to_string};
 use syntax::ptr::P;

src/librustc_save_analysis/lib.rs

@@ -54,7 +54,8 @@ use std::path::{Path, PathBuf};
 
 use syntax::ast::{self, NodeId, PatKind, Attribute, CRATE_NODE_ID};
 use syntax::parse::lexer::comments::strip_doc_comment_decoration;
-use syntax::parse::token::{self, keywords, InternedString};
+use syntax::parse::token;
+use syntax::symbol::{Symbol, keywords};
 use syntax::visit::{self, Visitor};
 use syntax::print::pprust::{ty_to_string, arg_to_string};
 use syntax::codemap::MacroAttribute;
@@ -119,7 +120,7 @@ impl<'l, 'tcx: 'l> SaveContext<'l, 'tcx> {
                 }
             };
             result.push(CrateData {
-                name: (&self.tcx.sess.cstore.crate_name(n)[..]).to_owned(),
+                name: self.tcx.sess.cstore.crate_name(n).to_string(),
                 number: n.as_u32(),
                 span: span,
             });
@@ -728,16 +729,16 @@ impl Visitor for PathCollector {
 }
 
 fn docs_for_attrs(attrs: &[Attribute]) -> String {
-    let doc = InternedString::new("doc");
+    let doc = Symbol::intern("doc");
     let mut result = String::new();
 
     for attr in attrs {
         if attr.name() == doc {
-            if let Some(ref val) = attr.value_str() {
-                if attr.node.is_sugared_doc {
-                    result.push_str(&strip_doc_comment_decoration(val));
+            if let Some(val) = attr.value_str() {
+                if attr.is_sugared_doc {
+                    result.push_str(&strip_doc_comment_decoration(&val.as_str()));
                 } else {
-                    result.push_str(val);
+                    result.push_str(&val.as_str());
                 }
                 result.push('\n');
             }

src/librustc_save_analysis/span_utils.rs

@@ -18,7 +18,8 @@ use std::path::Path;
 
 use syntax::ast;
 use syntax::parse::lexer::{self, Reader, StringReader};
-use syntax::parse::token::{self, keywords, Token};
+use syntax::parse::token::{self, Token};
+use syntax::symbol::keywords;
 use syntax_pos::*;
 
 #[derive(Clone)]

src/librustc_trans/asm.rs

@@ -88,7 +88,7 @@ pub fn trans_inline_asm<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
         AsmDialect::Intel => llvm::AsmDialect::Intel,
     };
 
-    let asm = CString::new(ia.asm.as_bytes()).unwrap();
+    let asm = CString::new(ia.asm.as_str().as_bytes()).unwrap();
     let constraint_cstr = CString::new(all_constraints).unwrap();
     let r = InlineAsmCall(bcx,
                           asm.as_ptr(),

src/librustc_trans/assert_module_sources.rs

@@ -29,7 +29,6 @@
 
 use rustc::ty::TyCtxt;
 use syntax::ast;
-use syntax::parse::token::InternedString;
 
 use {ModuleSource, ModuleTranslation};
 
@@ -77,7 +76,7 @@ impl<'a, 'tcx> AssertModuleSource<'a, 'tcx> {
         }
 
         let mname = self.field(attr, MODULE);
-        let mtrans = self.modules.iter().find(|mtrans| &mtrans.name[..] == &mname[..]);
+        let mtrans = self.modules.iter().find(|mtrans| *mtrans.name == *mname.as_str());
         let mtrans = match mtrans {
             Some(m) => m,
             None => {
@@ -113,7 +112,7 @@ impl<'a, 'tcx> AssertModuleSource<'a, 'tcx> {
         }
     }
 
-    fn field(&self, attr: &ast::Attribute, name: &str) -> InternedString {
+    fn field(&self, attr: &ast::Attribute, name: &str) -> ast::Name {
         for item in attr.meta_item_list().unwrap_or(&[]) {
             if item.check_name(name) {
                 if let Some(value) = item.value_str() {
@@ -137,7 +136,7 @@ impl<'a, 'tcx> AssertModuleSource<'a, 'tcx> {
         let config = &self.tcx.sess.parse_sess.config;
         let value = self.field(attr, CFG);
         debug!("check_config(config={:?}, value={:?})", config, value);
-        if config.iter().any(|c| c.check_name(&value[..])) {
+        if config.iter().any(|&(name, _)| name == value) {
             debug!("check_config: matched");
             return true;
         }

src/librustc_trans/back/link.rs

@@ -44,6 +44,7 @@ use std::str;
 use flate;
 use syntax::ast;
 use syntax::attr;
+use syntax::symbol::Symbol;
 use syntax_pos::Span;
 
 // RLIB LLVM-BYTECODE OBJECT LAYOUT
@@ -93,8 +94,8 @@ pub fn find_crate_name(sess: Option<&Session>,
 
     if let Some(sess) = sess {
         if let Some(ref s) = sess.opts.crate_name {
-            if let Some((attr, ref name)) = attr_crate_name {
-                if *s != &name[..] {
+            if let Some((attr, name)) = attr_crate_name {
+                if name != &**s {
                     let msg = format!("--crate-name and #[crate_name] are \
                                        required to match, but `{}` != `{}`",
                                       s, name);
@@ -130,7 +131,7 @@ pub fn build_link_meta(incremental_hashes_map: &IncrementalHashesMap,
                        name: &str)
                        -> LinkMeta {
     let r = LinkMeta {
-        crate_name: name.to_owned(),
+        crate_name: Symbol::intern(name),
         crate_hash: Svh::new(incremental_hashes_map[&DepNode::Krate].to_smaller_hash()),
     };
     info!("{:?}", r);
@@ -429,7 +430,7 @@ fn link_rlib<'a>(sess: &'a Session,
             NativeLibraryKind::NativeFramework |
             NativeLibraryKind::NativeUnknown => continue,
         }
-        ab.add_native_library(&lib.name);
+        ab.add_native_library(&lib.name.as_str());
     }
 
     // After adding all files to the archive, we need to update the
@@ -615,7 +616,7 @@ fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
         let skip_object_files = native_libs.iter().any(|lib| {
             lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
         });
-        ab.add_rlib(path, &name, sess.lto(), skip_object_files).unwrap();
+        ab.add_rlib(path, &name.as_str(), sess.lto(), skip_object_files).unwrap();
 
         all_native_libs.extend(sess.cstore.native_libraries(cnum));
     });
@@ -934,15 +935,15 @@ fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
         // don't otherwise explicitly reference them. This can occur for
         // libraries which are just providing bindings, libraries with generic
         // functions, etc.
-        cmd.link_whole_staticlib(&l.name, &search_path);
+        cmd.link_whole_staticlib(&l.name.as_str(), &search_path);
     }
 
     cmd.hint_dynamic();
 
     for lib in others {
         match lib.kind {
-            NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name),
-            NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name),
+            NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
+            NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
             NativeLibraryKind::NativeStatic => bug!(),
         }
     }
@@ -1185,8 +1186,8 @@ fn add_upstream_native_libraries(cmd: &mut Linker, sess: &Session) {
                 continue
             }
             match lib.kind {
-                NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name),
-                NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name),
+                NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
+                NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
 
                 // ignore statically included native libraries here as we've
                 // already included them when we included the rust library

src/librustc_trans/back/symbol_names.rs

@@ -113,7 +113,7 @@ use rustc::hir::map::definitions::{DefPath, DefPathData};
 use rustc::util::common::record_time;
 
 use syntax::attr;
-use syntax::parse::token::{self, InternedString};
+use syntax::symbol::{Symbol, InternedString};
 
 fn get_symbol_hash<'a, 'tcx>(scx: &SharedCrateContext<'a, 'tcx>,
 
@@ -275,7 +275,7 @@ impl ItemPathBuffer for SymbolPathBuffer {
     }
 
     fn push(&mut self, text: &str) {
-        self.names.push(token::intern(text).as_str());
+        self.names.push(Symbol::intern(text).as_str());
     }
 }
 
@@ -288,7 +288,7 @@ pub fn exported_name_from_type_and_prefix<'a, 'tcx>(scx: &SharedCrateContext<'a,
         krate: LOCAL_CRATE,
     };
     let hash = get_symbol_hash(scx, &empty_def_path, t, None);
-    let path = [token::intern_and_get_ident(prefix)];
+    let path = [Symbol::intern(prefix).as_str()];
     mangle(path.iter().cloned(), &hash)
 }
 

src/librustc_trans/base.rs

@@ -1128,11 +1128,11 @@ pub fn set_link_section(ccx: &CrateContext,
                         llval: ValueRef,
                         attrs: &[ast::Attribute]) {
     if let Some(sect) = attr::first_attr_value_str_by_name(attrs, "link_section") {
-        if contains_null(&sect) {
+        if contains_null(&sect.as_str()) {
             ccx.sess().fatal(&format!("Illegal null byte in link_section value: `{}`", &sect));
         }
         unsafe {
-            let buf = CString::new(sect.as_bytes()).unwrap();
+            let buf = CString::new(sect.as_str().as_bytes()).unwrap();
             llvm::LLVMSetSection(llval, buf.as_ptr());
         }
     }

src/librustc_trans/collector.rs

@@ -663,7 +663,7 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirNeighborCollector<'a, 'tcx> {
                                                 -> bool {
             (bare_fn_ty.abi == Abi::RustIntrinsic ||
              bare_fn_ty.abi == Abi::PlatformIntrinsic) &&
-            tcx.item_name(def_id).as_str() == "drop_in_place"
+            tcx.item_name(def_id) == "drop_in_place"
         }
     }
 }

src/librustc_trans/common.rs

@@ -52,8 +52,7 @@ use std::ffi::CString;
 use std::cell::{Cell, RefCell, Ref};
 
 use syntax::ast;
-use syntax::parse::token::InternedString;
-use syntax::parse::token;
+use syntax::symbol::{Symbol, InternedString};
 use syntax_pos::{DUMMY_SP, Span};
 
 pub use context::{CrateContext, SharedCrateContext};
@@ -225,7 +224,7 @@ impl<'a, 'tcx> VariantInfo<'tcx> {
                 VariantInfo {
                     discr: Disr(0),
                     fields: v.iter().enumerate().map(|(i, &t)| {
-                        Field(token::intern(&i.to_string()), t)
+                        Field(Symbol::intern(&i.to_string()), t)
                     }).collect()
                 }
             }

src/librustc_trans/consts.rs

@@ -123,7 +123,7 @@ pub fn get_static(ccx: &CrateContext, def_id: DefId) -> ValueRef {
                     // extern "C" fn() from being non-null, so we can't just declare a
                     // static and call it a day. Some linkages (like weak) will make it such
                     // that the static actually has a null value.
-                    let linkage = match base::llvm_linkage_by_name(&name) {
+                    let linkage = match base::llvm_linkage_by_name(&name.as_str()) {
                         Some(linkage) => linkage,
                         None => {
                             ccx.sess().span_fatal(span, "invalid linkage specified");

src/librustc_trans/context.rs

@@ -42,7 +42,7 @@ use std::ptr;
 use std::rc::Rc;
 use std::str;
 use syntax::ast;
-use syntax::parse::token::InternedString;
+use syntax::symbol::InternedString;
 use abi::FnType;
 
 pub struct Stats {

src/librustc_trans/debuginfo/metadata.rs

@@ -44,10 +44,8 @@ use std::ffi::CString;
 use std::fmt::Write;
 use std::path::Path;
 use std::ptr;
-use std::rc::Rc;
-use syntax::util::interner::Interner;
 use syntax::ast;
-use syntax::parse::token;
+use syntax::symbol::{Interner, InternedString};
 use syntax_pos::{self, Span};
 
 
@@ -117,9 +115,8 @@ impl<'tcx> TypeMap<'tcx> {
                                         unique_type_id: UniqueTypeId,
                                         metadata: DIType) {
         if self.unique_id_to_metadata.insert(unique_type_id, metadata).is_some() {
-            let unique_type_id_str = self.get_unique_type_id_as_string(unique_type_id);
             bug!("Type metadata for unique id '{}' is already in the TypeMap!",
-                 &unique_type_id_str[..]);
+                 self.get_unique_type_id_as_string(unique_type_id));
         }
     }
 
@@ -133,7 +130,7 @@ impl<'tcx> TypeMap<'tcx> {
 
     // Get the string representation of a UniqueTypeId. This method will fail if
     // the id is unknown.
-    fn get_unique_type_id_as_string(&self, unique_type_id: UniqueTypeId) -> Rc<str> {
+    fn get_unique_type_id_as_string(&self, unique_type_id: UniqueTypeId) -> &str {
         let UniqueTypeId(interner_key) = unique_type_id;
         self.unique_id_interner.get(interner_key)
     }
@@ -182,7 +179,7 @@ impl<'tcx> TypeMap<'tcx> {
                                               -> UniqueTypeId {
         let enum_type_id = self.get_unique_type_id_of_type(cx, enum_type);
         let enum_variant_type_id = format!("{}::{}",
-                                           &self.get_unique_type_id_as_string(enum_type_id),
+                                           self.get_unique_type_id_as_string(enum_type_id),
                                            variant_name);
         let interner_key = self.unique_id_interner.intern(&enum_variant_type_id);
         UniqueTypeId(interner_key)
@@ -623,14 +620,12 @@ pub fn type_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
             let metadata_for_uid = match type_map.find_metadata_for_unique_id(unique_type_id) {
                 Some(metadata) => metadata,
                 None => {
-                    let unique_type_id_str =
-                        type_map.get_unique_type_id_as_string(unique_type_id);
                     span_bug!(usage_site_span,
                               "Expected type metadata for unique \
                                type id '{}' to already be in \
                                the debuginfo::TypeMap but it \
                                was not. (Ty = {})",
-                              &unique_type_id_str[..],
+                              type_map.get_unique_type_id_as_string(unique_type_id),
                               t);
                 }
             };
@@ -638,14 +633,12 @@ pub fn type_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
             match type_map.find_metadata_for_type(t) {
                 Some(metadata) => {
                     if metadata != metadata_for_uid {
-                        let unique_type_id_str =
-                            type_map.get_unique_type_id_as_string(unique_type_id);
                         span_bug!(usage_site_span,
                                   "Mismatch between Ty and \
                                    UniqueTypeId maps in \
                                    debuginfo::TypeMap. \
                                    UniqueTypeId={}, Ty={}",
-                                  &unique_type_id_str[..],
+                                  type_map.get_unique_type_id_as_string(unique_type_id),
                                   t);
                     }
                 }
@@ -809,7 +802,7 @@ pub fn compile_unit_metadata(scc: &SharedCrateContext,
     };
 
     fn fallback_path(scc: &SharedCrateContext) -> CString {
-        CString::new(scc.link_meta().crate_name.clone()).unwrap()
+        CString::new(scc.link_meta().crate_name.to_string()).unwrap()
     }
 }
 
@@ -1526,13 +1519,10 @@ fn prepare_enum_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
     let enum_llvm_type = type_of::type_of(cx, enum_type);
     let (enum_type_size, enum_type_align) = size_and_align_of(cx, enum_llvm_type);
 
-    let unique_type_id_str = debug_context(cx)
-                             .type_map
-                             .borrow()
-                             .get_unique_type_id_as_string(unique_type_id);
-
     let enum_name = CString::new(enum_name).unwrap();
-    let unique_type_id_str = CString::new(unique_type_id_str.as_bytes()).unwrap();
+    let unique_type_id_str = CString::new(
+        debug_context(cx).type_map.borrow().get_unique_type_id_as_string(unique_type_id).as_bytes()
+    ).unwrap();
     let enum_metadata = unsafe {
         llvm::LLVMRustDIBuilderCreateUnionType(
         DIB(cx),
@@ -1566,7 +1556,7 @@ fn prepare_enum_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
 
     fn get_enum_discriminant_name(cx: &CrateContext,
                                   def_id: DefId)
-                                  -> token::InternedString {
+                                  -> InternedString {
         cx.tcx().item_name(def_id).as_str()
     }
 }
@@ -1669,11 +1659,10 @@ fn create_struct_stub(cx: &CrateContext,
                    -> DICompositeType {
     let (struct_size, struct_align) = size_and_align_of(cx, struct_llvm_type);
 
-    let unique_type_id_str = debug_context(cx).type_map
-                                              .borrow()
-                                              .get_unique_type_id_as_string(unique_type_id);
     let name = CString::new(struct_type_name).unwrap();
-    let unique_type_id = CString::new(unique_type_id_str.as_bytes()).unwrap();
+    let unique_type_id = CString::new(
+        debug_context(cx).type_map.borrow().get_unique_type_id_as_string(unique_type_id).as_bytes()
+    ).unwrap();
     let metadata_stub = unsafe {
         // LLVMRustDIBuilderCreateStructType() wants an empty array. A null
         // pointer will lead to hard to trace and debug LLVM assertions
@@ -1707,11 +1696,10 @@ fn create_union_stub(cx: &CrateContext,
                    -> DICompositeType {
     let (union_size, union_align) = size_and_align_of(cx, union_llvm_type);
 
-    let unique_type_id_str = debug_context(cx).type_map
-                                              .borrow()
-                                              .get_unique_type_id_as_string(unique_type_id);
     let name = CString::new(union_type_name).unwrap();
-    let unique_type_id = CString::new(unique_type_id_str.as_bytes()).unwrap();
+    let unique_type_id = CString::new(
+        debug_context(cx).type_map.borrow().get_unique_type_id_as_string(unique_type_id).as_bytes()
+    ).unwrap();
     let metadata_stub = unsafe {
         // LLVMRustDIBuilderCreateUnionType() wants an empty array. A null
         // pointer will lead to hard to trace and debug LLVM assertions

src/librustc_trans/debuginfo/namespace.rs

@@ -35,7 +35,7 @@ pub fn mangled_name_of_item(ccx: &CrateContext, def_id: DefId, extra: &str) -> S
         }
 
         let name = match def_key.disambiguated_data.data {
-            DefPathData::CrateRoot => ccx.tcx().crate_name(def_id.krate),
+            DefPathData::CrateRoot => ccx.tcx().crate_name(def_id.krate).as_str(),
             data => data.as_interned_str()
         };
 
@@ -64,7 +64,7 @@ pub fn item_namespace(ccx: &CrateContext, def_id: DefId) -> DIScope {
     });
 
     let namespace_name = match def_key.disambiguated_data.data {
-        DefPathData::CrateRoot => ccx.tcx().crate_name(def_id.krate),
+        DefPathData::CrateRoot => ccx.tcx().crate_name(def_id.krate).as_str(),
         data => data.as_interned_str()
     };
 

src/librustc_trans/debuginfo/type_names.rs

@@ -156,7 +156,7 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
                       qualified: bool,
                       output: &mut String) {
         if qualified {
-            output.push_str(&cx.tcx().crate_name(def_id.krate));
+            output.push_str(&cx.tcx().crate_name(def_id.krate).as_str());
             for path_element in cx.tcx().def_path(def_id).data {
                 output.push_str("::");
                 output.push_str(&path_element.data.as_interned_str());

src/librustc_trans/intrinsic.rs

@@ -30,7 +30,7 @@ use rustc::ty::{self, Ty};
 use Disr;
 use rustc::hir;
 use syntax::ast;
-use syntax::parse::token;
+use syntax::symbol::Symbol;
 
 use rustc::session::Session;
 use syntax_pos::{Span, DUMMY_SP};
@@ -107,7 +107,7 @@ pub fn trans_intrinsic_call<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
     let sig = tcx.erase_late_bound_regions_and_normalize(&fty.sig);
     let arg_tys = sig.inputs;
     let ret_ty = sig.output;
-    let name = tcx.item_name(def_id).as_str();
+    let name = &*tcx.item_name(def_id).as_str();
 
     let span = match call_debug_location {
         DebugLoc::ScopeAt(_, span) => span,
@@ -123,15 +123,15 @@ pub fn trans_intrinsic_call<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
         Call(bcx, llfn, &[], call_debug_location);
         Unreachable(bcx);
         return Result::new(bcx, C_undef(Type::nil(ccx).ptr_to()));
-    } else if &name[..] == "unreachable" {
+    } else if name == "unreachable" {
         Unreachable(bcx);
         return Result::new(bcx, C_nil(ccx));
     }
 
     let llret_ty = type_of::type_of(ccx, ret_ty);
 
-    let simple = get_simple_intrinsic(ccx, &name);
-    let llval = match (simple, &name[..]) {
+    let simple = get_simple_intrinsic(ccx, name);
+    let llval = match (simple, name) {
         (Some(llfn), _) => {
             Call(bcx, llfn, &llargs, call_debug_location)
         }
@@ -208,7 +208,7 @@ pub fn trans_intrinsic_call<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
         }
         (_, "type_name") => {
             let tp_ty = substs.type_at(0);
-            let ty_name = token::intern_and_get_ident(&tp_ty.to_string());
+            let ty_name = Symbol::intern(&tp_ty.to_string()).as_str();
             C_str_slice(ccx, ty_name)
         }
         (_, "type_id") => {
@@ -340,7 +340,7 @@ pub fn trans_intrinsic_call<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
             let sty = &arg_tys[0].sty;
             match int_type_width_signed(sty, ccx) {
                 Some((width, signed)) =>
-                    match &*name {
+                    match name {
                         "ctlz" => count_zeros_intrinsic(bcx, &format!("llvm.ctlz.i{}", width),
                                                         llargs[0], call_debug_location),
                         "cttz" => count_zeros_intrinsic(bcx, &format!("llvm.cttz.i{}", width),
@@ -394,7 +394,7 @@ pub fn trans_intrinsic_call<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
             let sty = &arg_tys[0].sty;
             match float_type_width(sty) {
                 Some(_width) =>
-                    match &*name {
+                    match name {
                         "fadd_fast" => FAddFast(bcx, llargs[0], llargs[1], call_debug_location),
                         "fsub_fast" => FSubFast(bcx, llargs[0], llargs[1], call_debug_location),
                         "fmul_fast" => FMulFast(bcx, llargs[0], llargs[1], call_debug_location),

src/librustc_trans/mir/block.rs

@@ -30,7 +30,7 @@ use glue;
 use type_::Type;
 
 use rustc_data_structures::fx::FxHashMap;
-use syntax::parse::token;
+use syntax::symbol::Symbol;
 
 use super::{MirContext, LocalRef};
 use super::analyze::CleanupKind;
@@ -324,7 +324,7 @@ impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
 
                 // Get the location information.
                 let loc = bcx.sess().codemap().lookup_char_pos(span.lo);
-                let filename = token::intern_and_get_ident(&loc.file.name);
+                let filename = Symbol::intern(&loc.file.name).as_str();
                 let filename = C_str_slice(bcx.ccx(), filename);
                 let line = C_u32(bcx.ccx(), loc.line as u32);
 
@@ -354,7 +354,7 @@ impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
                          const_err)
                     }
                     mir::AssertMessage::Math(ref err) => {
-                        let msg_str = token::intern_and_get_ident(err.description());
+                        let msg_str = Symbol::intern(err.description()).as_str();
                         let msg_str = C_str_slice(bcx.ccx(), msg_str);
                         let msg_file_line = C_struct(bcx.ccx(),
                                                      &[msg_str, filename, line],

src/librustc_trans/mir/mod.rs

@@ -21,7 +21,7 @@ use machine;
 use type_of;
 
 use syntax_pos::{DUMMY_SP, NO_EXPANSION, COMMAND_LINE_EXPN, BytePos};
-use syntax::parse::token::keywords;
+use syntax::symbol::keywords;
 
 use std::cell::Ref;
 use std::iter;

src/librustc_trans/partitioning.rs

@@ -132,7 +132,7 @@ use std::sync::Arc;
 use std::collections::hash_map::DefaultHasher;
 use symbol_map::SymbolMap;
 use syntax::ast::NodeId;
-use syntax::parse::token::{self, InternedString};
+use syntax::symbol::{Symbol, InternedString};
 use trans_item::TransItem;
 use util::nodemap::{FxHashMap, FxHashSet};
 
@@ -272,7 +272,7 @@ pub fn partition<'a, 'tcx, I>(scx: &SharedCrateContext<'a, 'tcx>,
     // If the partitioning should produce a fixed count of codegen units, merge
     // until that count is reached.
     if let PartitioningStrategy::FixedUnitCount(count) = strategy {
-        merge_codegen_units(&mut initial_partitioning, count, &tcx.crate_name[..]);
+        merge_codegen_units(&mut initial_partitioning, count, &tcx.crate_name.as_str());
 
         debug_dump(scx, "POST MERGING:", initial_partitioning.codegen_units.iter());
     }
@@ -320,7 +320,7 @@ fn place_root_translation_items<'a, 'tcx, I>(scx: &SharedCrateContext<'a, 'tcx>,
 
             let codegen_unit_name = match characteristic_def_id {
                 Some(def_id) => compute_codegen_unit_name(tcx, def_id, is_volatile),
-                None => InternedString::new(FALLBACK_CODEGEN_UNIT),
+                None => Symbol::intern(FALLBACK_CODEGEN_UNIT).as_str(),
             };
 
             let make_codegen_unit = || {
@@ -365,7 +365,7 @@ fn place_root_translation_items<'a, 'tcx, I>(scx: &SharedCrateContext<'a, 'tcx>,
     // always ensure we have at least one CGU; otherwise, if we have a
     // crate with just types (for example), we could wind up with no CGU
     if codegen_units.is_empty() {
-        let codegen_unit_name = InternedString::new(FALLBACK_CODEGEN_UNIT);
+        let codegen_unit_name = Symbol::intern(FALLBACK_CODEGEN_UNIT).as_str();
         codegen_units.entry(codegen_unit_name.clone())
                      .or_insert_with(|| CodegenUnit::empty(codegen_unit_name.clone()));
     }
@@ -523,7 +523,7 @@ fn compute_codegen_unit_name<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     let mut mod_path = String::with_capacity(64);
 
     let def_path = tcx.def_path(def_id);
-    mod_path.push_str(&tcx.crate_name(def_path.krate));
+    mod_path.push_str(&tcx.crate_name(def_path.krate).as_str());
 
     for part in tcx.def_path(def_id)
                    .data
@@ -542,14 +542,11 @@ fn compute_codegen_unit_name<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
         mod_path.push_str(".volatile");
     }
 
-    return token::intern_and_get_ident(&mod_path[..]);
+    return Symbol::intern(&mod_path[..]).as_str();
 }
 
 fn numbered_codegen_unit_name(crate_name: &str, index: usize) -> InternedString {
-    token::intern_and_get_ident(&format!("{}{}{}",
-        crate_name,
-        NUMBERED_CODEGEN_UNIT_MARKER,
-        index)[..])
+    Symbol::intern(&format!("{}{}{}", crate_name, NUMBERED_CODEGEN_UNIT_MARKER, index)).as_str()
 }
 
 fn debug_dump<'a, 'b, 'tcx, I>(scx: &SharedCrateContext<'a, 'tcx>,

src/librustc_trans/trans_item.rs

@@ -285,7 +285,7 @@ impl<'a, 'tcx> TransItem<'tcx> {
 
         let attributes = tcx.get_attrs(def_id);
         if let Some(name) = attr::first_attr_value_str_by_name(&attributes, "linkage") {
-            if let Some(linkage) = base::llvm_linkage_by_name(&name) {
+            if let Some(linkage) = base::llvm_linkage_by_name(&name.as_str()) {
                 Some(linkage)
             } else {
                 let span = tcx.map.span_if_local(def_id);
@@ -531,7 +531,7 @@ impl<'a, 'tcx> DefPathBasedNames<'a, 'tcx> {
 
         // some_crate::
         if !(self.omit_local_crate_name && def_id.is_local()) {
-            output.push_str(&self.tcx.crate_name(def_path.krate));
+            output.push_str(&self.tcx.crate_name(def_path.krate).as_str());
             output.push_str("::");
         }
 

src/librustc_typeck/astconv.rs

@@ -71,7 +71,7 @@ use util::nodemap::{NodeMap, FxHashSet};
 use std::cell::RefCell;
 use syntax::{abi, ast};
 use syntax::feature_gate::{GateIssue, emit_feature_err};
-use syntax::parse::token::{self, keywords};
+use syntax::symbol::{Symbol, keywords};
 use syntax_pos::{Span, Pos};
 use errors::DiagnosticBuilder;
 
@@ -645,7 +645,7 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
         };
 
         let output_binding = ConvertedBinding {
-            item_name: token::intern(FN_OUTPUT_NAME),
+            item_name: Symbol::intern(FN_OUTPUT_NAME),
             ty: output,
             span: output_span
         };
@@ -1252,7 +1252,7 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
         if bounds.len() > 1 {
             let spans = bounds.iter().map(|b| {
                 self.tcx().associated_items(b.def_id()).find(|item| {
-                    item.kind == ty::AssociatedKind::Type && item.name.as_str() == assoc_name
+                    item.kind == ty::AssociatedKind::Type && item.name == assoc_name
                 })
                 .and_then(|item| self.tcx().map.as_local_node_id(item.def_id))
                 .and_then(|node_id| self.tcx().map.opt_span(node_id))

src/librustc_typeck/check/autoderef.rs

@@ -20,7 +20,7 @@ use rustc::ty::{LvaluePreference, NoPreference, PreferMutLvalue};
 use rustc::hir;
 
 use syntax_pos::Span;
-use syntax::parse::token;
+use syntax::symbol::Symbol;
 
 #[derive(Copy, Clone, Debug)]
 enum AutoderefKind {
@@ -120,7 +120,7 @@ impl<'a, 'gcx, 'tcx> Autoderef<'a, 'gcx, 'tcx> {
         let normalized = traits::normalize_projection_type(&mut selcx,
                                                            ty::ProjectionTy {
                                                                trait_ref: trait_ref,
-                                                               item_name: token::intern("Target"),
+                                                               item_name: Symbol::intern("Target"),
                                                            },
                                                            cause,
                                                            0);
@@ -198,7 +198,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             (PreferMutLvalue, Some(trait_did)) => {
                 self.lookup_method_in_trait(span,
                                             base_expr,
-                                            token::intern("deref_mut"),
+                                            Symbol::intern("deref_mut"),
                                             trait_did,
                                             base_ty,
                                             None)
@@ -211,7 +211,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             (None, Some(trait_did)) => {
                 self.lookup_method_in_trait(span,
                                             base_expr,
-                                            token::intern("deref"),
+                                            Symbol::intern("deref"),
                                             trait_did,
                                             base_ty,
                                             None)

src/librustc_typeck/check/callee.rs

@@ -16,7 +16,7 @@ use hir::def_id::{DefId, LOCAL_CRATE};
 use hir::print;
 use rustc::{infer, traits};
 use rustc::ty::{self, LvaluePreference, Ty};
-use syntax::parse::token;
+use syntax::symbol::Symbol;
 use syntax::ptr::P;
 use syntax_pos::Span;
 
@@ -160,9 +160,9 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                                   -> Option<ty::MethodCallee<'tcx>> {
         // Try the options that are least restrictive on the caller first.
         for &(opt_trait_def_id, method_name) in
-            &[(self.tcx.lang_items.fn_trait(), token::intern("call")),
-              (self.tcx.lang_items.fn_mut_trait(), token::intern("call_mut")),
-              (self.tcx.lang_items.fn_once_trait(), token::intern("call_once"))] {
+            &[(self.tcx.lang_items.fn_trait(), Symbol::intern("call")),
+              (self.tcx.lang_items.fn_mut_trait(), Symbol::intern("call_mut")),
+              (self.tcx.lang_items.fn_once_trait(), Symbol::intern("call_once"))] {
             let trait_def_id = match opt_trait_def_id {
                 Some(def_id) => def_id,
                 None => continue,

src/librustc_typeck/check/intrinsic.rs

@@ -21,7 +21,7 @@ use {CrateCtxt, require_same_types};
 
 use syntax::abi::Abi;
 use syntax::ast;
-use syntax::parse::token;
+use syntax::symbol::Symbol;
 use syntax_pos::Span;
 
 use rustc::hir;
@@ -75,7 +75,7 @@ fn equate_intrinsic_type<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
 /// and in libcore/intrinsics.rs
 pub fn check_intrinsic_type(ccx: &CrateCtxt, it: &hir::ForeignItem) {
     fn param<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>, n: u32) -> Ty<'tcx> {
-        let name = token::intern(&format!("P{}", n));
+        let name = Symbol::intern(&format!("P{}", n));
         ccx.tcx.mk_param(n, name)
     }
 
@@ -326,7 +326,7 @@ pub fn check_intrinsic_type(ccx: &CrateCtxt, it: &hir::ForeignItem) {
 pub fn check_platform_intrinsic_type(ccx: &CrateCtxt,
                                      it: &hir::ForeignItem) {
     let param = |n| {
-        let name = token::intern(&format!("P{}", n));
+        let name = Symbol::intern(&format!("P{}", n));
         ccx.tcx.mk_param(n, name)
     };
 

src/librustc_typeck/check/method/mod.rs

@@ -342,7 +342,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         let def = pick.item.def();
         if let probe::InherentImplPick = pick.kind {
             if !pick.item.vis.is_accessible_from(self.body_id, &self.tcx.map) {
-                let msg = format!("{} `{}` is private", def.kind_name(), &method_name.as_str());
+                let msg = format!("{} `{}` is private", def.kind_name(), method_name);
                 self.tcx.sess.span_err(span, &msg);
             }
         }

src/librustc_typeck/check/mod.rs

@@ -115,8 +115,8 @@ use syntax::ast;
 use syntax::attr;
 use syntax::codemap::{self, original_sp, Spanned};
 use syntax::feature_gate::{GateIssue, emit_feature_err};
-use syntax::parse::token::{self, InternedString, keywords};
 use syntax::ptr::P;
+use syntax::symbol::{Symbol, InternedString, keywords};
 use syntax::util::lev_distance::find_best_match_for_name;
 use syntax_pos::{self, BytePos, Span};
 
@@ -931,7 +931,8 @@ fn check_on_unimplemented<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
     if let Some(ref attr) = item.attrs.iter().find(|a| {
         a.check_name("rustc_on_unimplemented")
     }) {
-        if let Some(ref istring) = attr.value_str() {
+        if let Some(istring) = attr.value_str() {
+            let istring = istring.as_str();
             let parser = Parser::new(&istring);
             let types = &generics.types;
             for token in parser {
@@ -942,7 +943,7 @@ fn check_on_unimplemented<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
                         Position::ArgumentNamed(s) if s == "Self" => (),
                         // So is `{A}` if A is a type parameter
                         Position::ArgumentNamed(s) => match types.iter().find(|t| {
-                            t.name.as_str() == s
+                            t.name == s
                         }) {
                             Some(_) => (),
                             None => {
@@ -2369,7 +2370,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             (PreferMutLvalue, Some(trait_did)) => {
                 self.lookup_method_in_trait_adjusted(expr.span,
                                                      Some(&base_expr),
-                                                     token::intern("index_mut"),
+                                                     Symbol::intern("index_mut"),
                                                      trait_did,
                                                      autoderefs,
                                                      unsize,
@@ -2384,7 +2385,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             (None, Some(trait_did)) => {
                 self.lookup_method_in_trait_adjusted(expr.span,
                                                      Some(&base_expr),
-                                                     token::intern("index"),
+                                                     Symbol::intern("index"),
                                                      trait_did,
                                                      autoderefs,
                                                      unsize,
@@ -3027,7 +3028,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
     fn suggest_field_name(variant: ty::VariantDef<'tcx>,
                           field: &Spanned<ast::Name>,
                           skip : Vec<InternedString>)
-                          -> Option<InternedString> {
+                          -> Option<Symbol> {
         let name = field.node.as_str();
         let names = variant.fields.iter().filter_map(|field| {
             // ignore already set fields and private fields from non-local crates
@@ -3126,7 +3127,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                 ty::TyAdt(adt, ..) if adt.is_enum() => {
                     struct_span_err!(self.tcx.sess, field.name.span, E0559,
                                     "{} `{}::{}` has no field named `{}`",
-                                    kind_name, actual, variant.name.as_str(), field.name.node)
+                                    kind_name, actual, variant.name, field.name.node)
                 }
                 _ => {
                     struct_span_err!(self.tcx.sess, field.name.span, E0560,
@@ -3146,7 +3147,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             match ty.sty {
                 ty::TyAdt(adt, ..) if adt.is_enum() => {
                     err.span_label(field.name.span, &format!("`{}::{}` does not have this field",
-                                                             ty, variant.name.as_str()));
+                                                             ty, variant.name));
                 }
                 _ => {
                     err.span_label(field.name.span, &format!("`{}` does not have this field", ty));

src/librustc_typeck/check/op.rs

@@ -14,7 +14,7 @@ use super::FnCtxt;
 use hir::def_id::DefId;
 use rustc::ty::{Ty, TypeFoldable, PreferMutLvalue};
 use syntax::ast;
-use syntax::parse::token;
+use syntax::symbol::Symbol;
 use rustc::hir;
 
 impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
@@ -182,7 +182,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         let rhs_ty_var = self.next_ty_var();
 
         let return_ty = match self.lookup_op_method(expr, lhs_ty, vec![rhs_ty_var],
-                                                    token::intern(name), trait_def_id,
+                                                    Symbol::intern(name), trait_def_id,
                                                     lhs_expr) {
             Ok(return_ty) => return_ty,
             Err(()) => {
@@ -248,9 +248,8 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                            -> Ty<'tcx>
     {
         assert!(op.is_by_value());
-        match self.lookup_op_method(ex, operand_ty, vec![],
-                                    token::intern(mname), trait_did,
-                                    operand_expr) {
+        let mname = Symbol::intern(mname);
+        match self.lookup_op_method(ex, operand_ty, vec![], mname, trait_did, operand_expr) {
             Ok(t) => t,
             Err(()) => {
                 self.type_error_message(ex.span, |actual| {

src/librustc_typeck/collect.rs

@@ -79,7 +79,7 @@ use rustc_const_math::ConstInt;
 use std::cell::RefCell;
 
 use syntax::{abi, ast, attr};
-use syntax::parse::token::{self, keywords};
+use syntax::symbol::{Symbol, keywords};
 use syntax_pos::Span;
 
 use rustc::hir::{self, map as hir_map, print as pprust};
@@ -585,7 +585,7 @@ fn convert_closure<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
     let upvar_decls : Vec<_> = tcx.with_freevars(node_id, |fv| {
         fv.iter().enumerate().map(|(i, _)| ty::TypeParameterDef {
             index: (base_generics.count() as u32) + (i as u32),
-            name: token::intern("<upvar>"),
+            name: Symbol::intern("<upvar>"),
             def_id: def_id,
             default_def_id: base_def_id,
             default: None,

src/librustdoc/clean/mod.rs

@@ -24,9 +24,9 @@ use syntax::abi::Abi;
 use syntax::ast;
 use syntax::attr;
 use syntax::codemap::Spanned;
-use syntax::parse::token::keywords;
 use syntax::ptr::P;
 use syntax::print::pprust as syntax_pprust;
+use syntax::symbol::keywords;
 use syntax_pos::{self, DUMMY_SP, Pos};
 
 use rustc_trans::back::link;
@@ -242,7 +242,7 @@ impl Clean<ExternalCrate> for CrateNum {
             }
         });
         ExternalCrate {
-            name: (&cx.sess().cstore.crate_name(self.0)[..]).to_owned(),
+            name: cx.sess().cstore.crate_name(self.0).to_string(),
             attrs: cx.sess().cstore.item_attrs(root).clean(cx),
             primitives: primitives,
         }
@@ -2577,7 +2577,7 @@ impl Clean<Vec<Item>> for doctree::Import {
         // #[doc(no_inline)] attribute is present.
         // Don't inline doc(hidden) imports so they can be stripped at a later stage.
         let denied = self.vis != hir::Public || self.attrs.iter().any(|a| {
-            &a.name()[..] == "doc" && match a.meta_item_list() {
+            a.name() == "doc" && match a.meta_item_list() {
                 Some(l) => attr::list_contains_name(l, "no_inline") ||
                            attr::list_contains_name(l, "hidden"),
                 None => false,

src/libsyntax/ast.rs

@@ -14,71 +14,43 @@ pub use self::TyParamBound::*;
 pub use self::UnsafeSource::*;
 pub use self::ViewPath_::*;
 pub use self::PathParameters::*;
+pub use symbol::Symbol as Name;
 pub use util::ThinVec;
 
 use syntax_pos::{mk_sp, Span, DUMMY_SP, ExpnId};
 use codemap::{respan, Spanned};
 use abi::Abi;
 use ext::hygiene::SyntaxContext;
-use parse::token::{self, keywords, InternedString};
 use print::pprust;
 use ptr::P;
+use symbol::{Symbol, keywords};
 use tokenstream::{TokenTree};
 
+use std::collections::HashSet;
 use std::fmt;
 use std::rc::Rc;
 use std::u32;
 
 use serialize::{self, Encodable, Decodable, Encoder, Decoder};
 
-/// A name is a part of an identifier, representing a string or gensym. It's
-/// the result of interning.
-#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct Name(pub u32);
-
 /// An identifier contains a Name (index into the interner
 /// table) and a SyntaxContext to track renaming and
 /// macro expansion per Flatt et al., "Macros That Work Together"
 #[derive(Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Ident {
-    pub name: Name,
+    pub name: Symbol,
     pub ctxt: SyntaxContext
 }
 
-impl Name {
-    pub fn as_str(self) -> token::InternedString {
-        token::InternedString::new_from_name(self)
-    }
-}
-
-impl fmt::Debug for Name {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}({})", self, self.0)
-    }
-}
-
-impl fmt::Display for Name {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Display::fmt(&self.as_str(), f)
-    }
-}
-
-impl Encodable for Name {
-    fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
-        s.emit_str(&self.as_str())
-    }
-}
-
-impl Decodable for Name {
-    fn decode<D: Decoder>(d: &mut D) -> Result<Name, D::Error> {
-        Ok(token::intern(&d.read_str()?))
-    }
-}
-
 impl Ident {
     pub const fn with_empty_ctxt(name: Name) -> Ident {
         Ident { name: name, ctxt: SyntaxContext::empty() }
     }
+
+   /// Maps a string to an identifier with an empty syntax context.
+   pub fn from_str(s: &str) -> Ident {
+       Ident::with_empty_ctxt(Symbol::intern(s))
+   }
 }
 
 impl fmt::Debug for Ident {
@@ -401,7 +373,7 @@ impl Generics {
     }
     pub fn span_for_name(&self, name: &str) -> Option<Span> {
         for t in &self.ty_params {
-            if t.ident.name.as_str() == name {
+            if t.ident.name == name {
                 return Some(t.span);
             }
         }
@@ -479,7 +451,7 @@ pub struct WhereEqPredicate {
 
 /// The set of MetaItems that define the compilation environment of the crate,
 /// used to drive conditional compilation
-pub type CrateConfig = Vec<P<MetaItem>>;
+pub type CrateConfig = HashSet<(Name, Option<Symbol>)>;
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub struct Crate {
@@ -498,7 +470,7 @@ pub type NestedMetaItem = Spanned<NestedMetaItemKind>;
 #[derive(Clone, Eq, RustcEncodable, RustcDecodable, Hash, Debug, PartialEq)]
 pub enum NestedMetaItemKind {
     /// A full MetaItem, for recursive meta items.
-    MetaItem(P<MetaItem>),
+    MetaItem(MetaItem),
     /// A literal.
     ///
     /// E.g. "foo", 64, true
@@ -508,53 +480,30 @@ pub enum NestedMetaItemKind {
 /// A spanned compile-time attribute item.
 ///
 /// E.g. `#[test]`, `#[derive(..)]` or `#[feature = "foo"]`
-pub type MetaItem = Spanned<MetaItemKind>;
+#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
+pub struct MetaItem {
+    pub name: Name,
+    pub node: MetaItemKind,
+    pub span: Span,
+}
 
 /// A compile-time attribute item.
 ///
 /// E.g. `#[test]`, `#[derive(..)]` or `#[feature = "foo"]`
-#[derive(Clone, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
+#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub enum MetaItemKind {
     /// Word meta item.
     ///
     /// E.g. `test` as in `#[test]`
-    Word(InternedString),
+    Word,
     /// List meta item.
     ///
     /// E.g. `derive(..)` as in `#[derive(..)]`
-    List(InternedString, Vec<NestedMetaItem>),
+    List(Vec<NestedMetaItem>),
     /// Name value meta item.
     ///
     /// E.g. `feature = "foo"` as in `#[feature = "foo"]`
-    NameValue(InternedString, Lit),
-}
-
-// can't be derived because the MetaItemKind::List requires an unordered comparison
-impl PartialEq for MetaItemKind {
-    fn eq(&self, other: &MetaItemKind) -> bool {
-        use self::MetaItemKind::*;
-        match *self {
-            Word(ref ns) => match *other {
-                Word(ref no) => (*ns) == (*no),
-                _ => false
-            },
-            List(ref ns, ref miss) => match *other {
-                List(ref no, ref miso) => {
-                    ns == no &&
-                        miss.iter().all(|mi| {
-                            miso.iter().any(|x| x.node == mi.node)
-                        })
-                }
-                _ => false
-            },
-            NameValue(ref ns, ref vs) => match *other {
-                NameValue(ref no, ref vo) => {
-                    (*ns) == (*no) && vs.node == vo.node
-                }
-                _ => false
-            },
-        }
-    }
+    NameValue(Lit)
 }
 
 /// A Block (`{ .. }`).
@@ -1149,7 +1098,7 @@ pub enum LitIntType {
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub enum LitKind {
     /// A string literal (`"foo"`)
-    Str(InternedString, StrStyle),
+    Str(Symbol, StrStyle),
     /// A byte string (`b"foo"`)
     ByteStr(Rc<Vec<u8>>),
     /// A byte char (`b'f'`)
@@ -1159,9 +1108,9 @@ pub enum LitKind {
     /// An integer literal (`1`)
     Int(u64, LitIntType),
     /// A float literal (`1f64` or `1E10f64`)
-    Float(InternedString, FloatTy),
+    Float(Symbol, FloatTy),
     /// A float literal without a suffix (`1.0 or 1.0E10`)
-    FloatUnsuffixed(InternedString),
+    FloatUnsuffixed(Symbol),
     /// A boolean literal
     Bool(bool),
 }
@@ -1493,7 +1442,7 @@ pub enum AsmDialect {
 /// E.g. `"={eax}"(result)` as in `asm!("mov eax, 2" : "={eax}"(result) : : : "intel")``
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub struct InlineAsmOutput {
-    pub constraint: InternedString,
+    pub constraint: Symbol,
     pub expr: P<Expr>,
     pub is_rw: bool,
     pub is_indirect: bool,
@@ -1504,11 +1453,11 @@ pub struct InlineAsmOutput {
 /// E.g. `asm!("NOP");`
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub struct InlineAsm {
-    pub asm: InternedString,
+    pub asm: Symbol,
     pub asm_str_style: StrStyle,
     pub outputs: Vec<InlineAsmOutput>,
-    pub inputs: Vec<(InternedString, P<Expr>)>,
-    pub clobbers: Vec<InternedString>,
+    pub inputs: Vec<(Symbol, P<Expr>)>,
+    pub clobbers: Vec<Symbol>,
     pub volatile: bool,
     pub alignstack: bool,
     pub dialect: AsmDialect,
@@ -1755,8 +1704,6 @@ impl ViewPath_ {
     }
 }
 
-/// Meta-data associated with an item
-pub type Attribute = Spanned<Attribute_>;
 
 /// Distinguishes between Attributes that decorate items and Attributes that
 /// are contained as statements within items. These two cases need to be
@@ -1770,13 +1717,15 @@ pub enum AttrStyle {
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 pub struct AttrId(pub usize);
 
+/// Meta-data associated with an item
 /// Doc-comments are promoted to attributes that have is_sugared_doc = true
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
-pub struct Attribute_ {
+pub struct Attribute {
     pub id: AttrId,
     pub style: AttrStyle,
-    pub value: P<MetaItem>,
+    pub value: MetaItem,
     pub is_sugared_doc: bool,
+    pub span: Span,
 }
 
 /// TraitRef's appear in impls.

src/libsyntax/attr.rs

@@ -15,17 +15,17 @@ pub use self::ReprAttr::*;
 pub use self::IntType::*;
 
 use ast;
-use ast::{AttrId, Attribute, Attribute_};
+use ast::{AttrId, Attribute, Name};
 use ast::{MetaItem, MetaItemKind, NestedMetaItem, NestedMetaItemKind};
 use ast::{Lit, Expr, Item, Local, Stmt, StmtKind};
-use codemap::{respan, spanned, dummy_spanned};
+use codemap::{spanned, dummy_spanned, mk_sp};
 use syntax_pos::{Span, BytePos, DUMMY_SP};
 use errors::Handler;
 use feature_gate::{Features, GatedCfg};
 use parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
-use parse::token::InternedString;
-use parse::{ParseSess, token};
+use parse::ParseSess;
 use ptr::P;
+use symbol::Symbol;
 use util::ThinVec;
 
 use std::cell::{RefCell, Cell};
@@ -37,8 +37,8 @@ thread_local! {
 }
 
 enum AttrError {
-    MultipleItem(InternedString),
-    UnknownMetaItem(InternedString),
+    MultipleItem(Name),
+    UnknownMetaItem(Name),
     MissingSince,
     MissingFeature,
     MultipleStabilityLevels,
@@ -61,7 +61,7 @@ fn handle_errors(diag: &Handler, span: Span, error: AttrError) {
 
 pub fn mark_used(attr: &Attribute) {
     debug!("Marking {:?} as used.", attr);
-    let AttrId(id) = attr.node.id;
+    let AttrId(id) = attr.id;
     USED_ATTRS.with(|slot| {
         let idx = (id / 64) as usize;
         let shift = id % 64;
@@ -73,7 +73,7 @@ pub fn mark_used(attr: &Attribute) {
 }
 
 pub fn is_used(attr: &Attribute) -> bool {
-    let AttrId(id) = attr.node.id;
+    let AttrId(id) = attr.id;
     USED_ATTRS.with(|slot| {
         let idx = (id / 64) as usize;
         let shift = id % 64;
@@ -84,7 +84,7 @@ pub fn is_used(attr: &Attribute) -> bool {
 
 pub fn mark_known(attr: &Attribute) {
     debug!("Marking {:?} as known.", attr);
-    let AttrId(id) = attr.node.id;
+    let AttrId(id) = attr.id;
     KNOWN_ATTRS.with(|slot| {
         let idx = (id / 64) as usize;
         let shift = id % 64;
@@ -96,7 +96,7 @@ pub fn mark_known(attr: &Attribute) {
 }
 
 pub fn is_known(attr: &Attribute) -> bool {
-    let AttrId(id) = attr.node.id;
+    let AttrId(id) = attr.id;
     KNOWN_ATTRS.with(|slot| {
         let idx = (id / 64) as usize;
         let shift = id % 64;
@@ -107,7 +107,7 @@ pub fn is_known(attr: &Attribute) -> bool {
 
 impl NestedMetaItem {
     /// Returns the MetaItem if self is a NestedMetaItemKind::MetaItem.
-    pub fn meta_item(&self) -> Option<&P<MetaItem>> {
+    pub fn meta_item(&self) -> Option<&MetaItem> {
         match self.node {
             NestedMetaItemKind::MetaItem(ref item) => Some(&item),
             _ => None
@@ -134,18 +134,18 @@ impl NestedMetaItem {
 
     /// Returns the name of the meta item, e.g. `foo` in `#[foo]`,
     /// `#[foo="bar"]` and `#[foo(bar)]`, if self is a MetaItem
-    pub fn name(&self) -> Option<InternedString> {
+    pub fn name(&self) -> Option<Name> {
         self.meta_item().and_then(|meta_item| Some(meta_item.name()))
     }
 
     /// Gets the string value if self is a MetaItem and the MetaItem is a
     /// MetaItemKind::NameValue variant containing a string, otherwise None.
-    pub fn value_str(&self) -> Option<InternedString> {
+    pub fn value_str(&self) -> Option<Symbol> {
         self.meta_item().and_then(|meta_item| meta_item.value_str())
     }
 
     /// Returns a MetaItem if self is a MetaItem with Kind Word.
-    pub fn word(&self) -> Option<&P<MetaItem>> {
+    pub fn word(&self) -> Option<&MetaItem> {
         self.meta_item().and_then(|meta_item| if meta_item.is_word() {
             Some(meta_item)
         } else {
@@ -186,16 +186,16 @@ impl NestedMetaItem {
 
 impl Attribute {
     pub fn check_name(&self, name: &str) -> bool {
-        let matches = name == &self.name()[..];
+        let matches = self.name() == name;
         if matches {
             mark_used(self);
         }
         matches
     }
 
-    pub fn name(&self) -> InternedString { self.meta().name() }
+    pub fn name(&self) -> Name { self.meta().name() }
 
-    pub fn value_str(&self) -> Option<InternedString> {
+    pub fn value_str(&self) -> Option<Symbol> {
         self.meta().value_str()
     }
 
@@ -218,17 +218,13 @@ impl Attribute {
 }
 
 impl MetaItem {
-    pub fn name(&self) -> InternedString {
-        match self.node {
-            MetaItemKind::Word(ref n) => (*n).clone(),
-            MetaItemKind::NameValue(ref n, _) => (*n).clone(),
-            MetaItemKind::List(ref n, _) => (*n).clone(),
-        }
+    pub fn name(&self) -> Name {
+        self.name
     }
 
-    pub fn value_str(&self) -> Option<InternedString> {
+    pub fn value_str(&self) -> Option<Symbol> {
         match self.node {
-            MetaItemKind::NameValue(_, ref v) => {
+            MetaItemKind::NameValue(ref v) => {
                 match v.node {
                     ast::LitKind::Str(ref s, _) => Some((*s).clone()),
                     _ => None,
@@ -240,14 +236,14 @@ impl MetaItem {
 
     pub fn meta_item_list(&self) -> Option<&[NestedMetaItem]> {
         match self.node {
-            MetaItemKind::List(_, ref l) => Some(&l[..]),
+            MetaItemKind::List(ref l) => Some(&l[..]),
             _ => None
         }
     }
 
     pub fn is_word(&self) -> bool {
         match self.node {
-            MetaItemKind::Word(_) => true,
+            MetaItemKind::Word => true,
             _ => false,
         }
     }
@@ -255,7 +251,7 @@ impl MetaItem {
     pub fn span(&self) -> Span { self.span }
 
     pub fn check_name(&self, name: &str) -> bool {
-        name == &self.name()[..]
+        self.name() == name
     }
 
     pub fn is_value_str(&self) -> bool {
@@ -270,7 +266,7 @@ impl MetaItem {
 impl Attribute {
     /// Extract the MetaItem from inside this Attribute.
     pub fn meta(&self) -> &MetaItem {
-        &self.node.value
+        &self.value
     }
 
     /// Convert self to a normal #[doc="foo"] comment, if it is a
@@ -279,16 +275,15 @@ impl Attribute {
     pub fn with_desugared_doc<T, F>(&self, f: F) -> T where
         F: FnOnce(&Attribute) -> T,
     {
-        if self.node.is_sugared_doc {
+        if self.is_sugared_doc {
             let comment = self.value_str().unwrap();
             let meta = mk_name_value_item_str(
-                InternedString::new("doc"),
-                token::intern_and_get_ident(&strip_doc_comment_decoration(
-                        &comment)));
-            if self.node.style == ast::AttrStyle::Outer {
-                f(&mk_attr_outer(self.node.id, meta))
+                Symbol::intern("doc"),
+                Symbol::intern(&strip_doc_comment_decoration(&comment.as_str())));
+            if self.style == ast::AttrStyle::Outer {
+                f(&mk_attr_outer(self.id, meta))
             } else {
-                f(&mk_attr_inner(self.node.id, meta))
+                f(&mk_attr_inner(self.id, meta))
             }
         } else {
             f(self)
@@ -298,41 +293,37 @@ impl Attribute {
 
 /* Constructors */
 
-pub fn mk_name_value_item_str(name: InternedString, value: InternedString)
-                              -> P<MetaItem> {
+pub fn mk_name_value_item_str(name: Name, value: Symbol) -> MetaItem {
     let value_lit = dummy_spanned(ast::LitKind::Str(value, ast::StrStyle::Cooked));
     mk_spanned_name_value_item(DUMMY_SP, name, value_lit)
 }
 
-pub fn mk_name_value_item(name: InternedString, value: ast::Lit)
-                          -> P<MetaItem> {
+pub fn mk_name_value_item(name: Name, value: ast::Lit) -> MetaItem {
     mk_spanned_name_value_item(DUMMY_SP, name, value)
 }
 
-pub fn mk_list_item(name: InternedString, items: Vec<NestedMetaItem>) -> P<MetaItem> {
+pub fn mk_list_item(name: Name, items: Vec<NestedMetaItem>) -> MetaItem {
     mk_spanned_list_item(DUMMY_SP, name, items)
 }
 
-pub fn mk_list_word_item(name: InternedString) -> ast::NestedMetaItem {
+pub fn mk_list_word_item(name: Name) -> ast::NestedMetaItem {
     dummy_spanned(NestedMetaItemKind::MetaItem(mk_spanned_word_item(DUMMY_SP, name)))
 }
 
-pub fn mk_word_item(name: InternedString) -> P<MetaItem> {
+pub fn mk_word_item(name: Name) -> MetaItem {
     mk_spanned_word_item(DUMMY_SP, name)
 }
 
-pub fn mk_spanned_name_value_item(sp: Span, name: InternedString, value: ast::Lit)
-                          -> P<MetaItem> {
-    P(respan(sp, MetaItemKind::NameValue(name, value)))
+pub fn mk_spanned_name_value_item(sp: Span, name: Name, value: ast::Lit) -> MetaItem {
+    MetaItem { span: sp, name: name, node: MetaItemKind::NameValue(value) }
 }
 
-pub fn mk_spanned_list_item(sp: Span, name: InternedString, items: Vec<NestedMetaItem>)
-                            -> P<MetaItem> {
-    P(respan(sp, MetaItemKind::List(name, items)))
+pub fn mk_spanned_list_item(sp: Span, name: Name, items: Vec<NestedMetaItem>) -> MetaItem {
+    MetaItem { span: sp, name: name, node: MetaItemKind::List(items) }
 }
 
-pub fn mk_spanned_word_item(sp: Span, name: InternedString) -> P<MetaItem> {
-    P(respan(sp, MetaItemKind::Word(name)))
+pub fn mk_spanned_word_item(sp: Span, name: Name) -> MetaItem {
+    MetaItem { span: sp, name: name, node: MetaItemKind::Word }
 }
 
 
@@ -349,71 +340,63 @@ pub fn mk_attr_id() -> AttrId {
 }
 
 /// Returns an inner attribute with the given value.
-pub fn mk_attr_inner(id: AttrId, item: P<MetaItem>) -> Attribute {
+pub fn mk_attr_inner(id: AttrId, item: MetaItem) -> Attribute {
     mk_spanned_attr_inner(DUMMY_SP, id, item)
 }
 
 /// Returns an innter attribute with the given value and span.
-pub fn mk_spanned_attr_inner(sp: Span, id: AttrId, item: P<MetaItem>) -> Attribute {
-    respan(sp,
-           Attribute_ {
-            id: id,
-            style: ast::AttrStyle::Inner,
-            value: item,
-            is_sugared_doc: false,
-          })
+pub fn mk_spanned_attr_inner(sp: Span, id: AttrId, item: MetaItem) -> Attribute {
+    Attribute {
+        id: id,
+        style: ast::AttrStyle::Inner,
+        value: item,
+        is_sugared_doc: false,
+        span: sp,
+    }
 }
 
 
 /// Returns an outer attribute with the given value.
-pub fn mk_attr_outer(id: AttrId, item: P<MetaItem>) -> Attribute {
+pub fn mk_attr_outer(id: AttrId, item: MetaItem) -> Attribute {
     mk_spanned_attr_outer(DUMMY_SP, id, item)
 }
 
 /// Returns an outer attribute with the given value and span.
-pub fn mk_spanned_attr_outer(sp: Span, id: AttrId, item: P<MetaItem>) -> Attribute {
-    respan(sp,
-           Attribute_ {
-            id: id,
-            style: ast::AttrStyle::Outer,
-            value: item,
-            is_sugared_doc: false,
-          })
+pub fn mk_spanned_attr_outer(sp: Span, id: AttrId, item: MetaItem) -> Attribute {
+    Attribute {
+        id: id,
+        style: ast::AttrStyle::Outer,
+        value: item,
+        is_sugared_doc: false,
+        span: sp,
+    }
 }
 
-pub fn mk_doc_attr_outer(id: AttrId, item: P<MetaItem>, is_sugared_doc: bool) -> Attribute {
-    dummy_spanned(Attribute_ {
+pub fn mk_doc_attr_outer(id: AttrId, item: MetaItem, is_sugared_doc: bool) -> Attribute {
+    Attribute {
         id: id,
         style: ast::AttrStyle::Outer,
         value: item,
         is_sugared_doc: is_sugared_doc,
-    })
+        span: DUMMY_SP,
+    }
 }
 
-pub fn mk_sugared_doc_attr(id: AttrId, text: InternedString, lo: BytePos,
-                           hi: BytePos)
+pub fn mk_sugared_doc_attr(id: AttrId, text: Symbol, lo: BytePos, hi: BytePos)
                            -> Attribute {
-    let style = doc_comment_style(&text);
+    let style = doc_comment_style(&text.as_str());
     let lit = spanned(lo, hi, ast::LitKind::Str(text, ast::StrStyle::Cooked));
-    let attr = Attribute_ {
+    Attribute {
         id: id,
         style: style,
-        value: P(spanned(lo, hi, MetaItemKind::NameValue(InternedString::new("doc"), lit))),
-        is_sugared_doc: true
-    };
-    spanned(lo, hi, attr)
-}
-
-/* Searching */
-/// Check if `needle` occurs in `haystack` by a structural
-/// comparison. This is slightly subtle, and relies on ignoring the
-/// span included in the `==` comparison a plain MetaItem.
-pub fn contains(haystack: &[P<MetaItem>], needle: &MetaItem) -> bool {
-    debug!("attr::contains (name={})", needle.name());
-    haystack.iter().any(|item| {
-        debug!("  testing: {}", item.name());
-        item.node == needle.node
-    })
+        value: MetaItem {
+            span: mk_sp(lo, hi),
+            name: Symbol::intern("doc"),
+            node: MetaItemKind::NameValue(lit),
+        },
+        is_sugared_doc: true,
+        span: mk_sp(lo, hi),
+    }
 }
 
 pub fn list_contains_name(items: &[NestedMetaItem], name: &str) -> bool {
@@ -432,15 +415,13 @@ pub fn contains_name(attrs: &[Attribute], name: &str) -> bool {
     })
 }
 
-pub fn first_attr_value_str_by_name(attrs: &[Attribute], name: &str)
-                                 -> Option<InternedString> {
+pub fn first_attr_value_str_by_name(attrs: &[Attribute], name: &str) -> Option<Symbol> {
     attrs.iter()
         .find(|at| at.check_name(name))
         .and_then(|at| at.value_str())
 }
 
-pub fn last_meta_item_value_str_by_name(items: &[P<MetaItem>], name: &str)
-                                     -> Option<InternedString> {
+pub fn last_meta_item_value_str_by_name(items: &[MetaItem], name: &str) -> Option<Symbol> {
     items.iter()
          .rev()
          .find(|mi| mi.check_name(name))
@@ -449,12 +430,12 @@ pub fn last_meta_item_value_str_by_name(items: &[P<MetaItem>], name: &str)
 
 /* Higher-level applications */
 
-pub fn find_crate_name(attrs: &[Attribute]) -> Option<InternedString> {
+pub fn find_crate_name(attrs: &[Attribute]) -> Option<Symbol> {
     first_attr_value_str_by_name(attrs, "crate_name")
 }
 
 /// Find the value of #[export_name=*] attribute and check its validity.
-pub fn find_export_name_attr(diag: &Handler, attrs: &[Attribute]) -> Option<InternedString> {
+pub fn find_export_name_attr(diag: &Handler, attrs: &[Attribute]) -> Option<Symbol> {
     attrs.iter().fold(None, |ia,attr| {
         if attr.check_name("export_name") {
             if let s@Some(_) = attr.value_str() {
@@ -488,13 +469,14 @@ pub enum InlineAttr {
 
 /// Determine what `#[inline]` attribute is present in `attrs`, if any.
 pub fn find_inline_attr(diagnostic: Option<&Handler>, attrs: &[Attribute]) -> InlineAttr {
-    attrs.iter().fold(InlineAttr::None, |ia,attr| {
-        match attr.node.value.node {
-            MetaItemKind::Word(ref n) if n == "inline" => {
+    attrs.iter().fold(InlineAttr::None, |ia, attr| {
+        match attr.value.node {
+            _ if attr.value.name != "inline" => ia,
+            MetaItemKind::Word => {
                 mark_used(attr);
                 InlineAttr::Hint
             }
-            MetaItemKind::List(ref n, ref items) if n == "inline" => {
+            MetaItemKind::List(ref items) => {
                 mark_used(attr);
                 if items.len() != 1 {
                     diagnostic.map(|d|{ span_err!(d, attr.span, E0534, "expected one argument"); });
@@ -527,7 +509,7 @@ pub fn requests_inline(attrs: &[Attribute]) -> bool {
 /// Tests if a cfg-pattern matches the cfg set
 pub fn cfg_matches(cfg: &ast::MetaItem, sess: &ParseSess, features: Option<&Features>) -> bool {
     match cfg.node {
-        ast::MetaItemKind::List(ref pred, ref mis) => {
+        ast::MetaItemKind::List(ref mis) => {
             for mi in mis.iter() {
                 if !mi.is_meta_item() {
                     handle_errors(&sess.span_diagnostic, mi.span, AttrError::UnsupportedLiteral);
@@ -537,7 +519,7 @@ pub fn cfg_matches(cfg: &ast::MetaItem, sess: &ParseSess, features: Option<&Feat
 
             // The unwraps below may look dangerous, but we've already asserted
             // that they won't fail with the loop above.
-            match &pred[..] {
+            match &*cfg.name.as_str() {
                 "any" => mis.iter().any(|mi| {
                     cfg_matches(mi.meta_item().unwrap(), sess, features)
                 }),
@@ -558,11 +540,11 @@ pub fn cfg_matches(cfg: &ast::MetaItem, sess: &ParseSess, features: Option<&Feat
                 }
             }
         },
-        ast::MetaItemKind::Word(_) | ast::MetaItemKind::NameValue(..) => {
+        ast::MetaItemKind::Word | ast::MetaItemKind::NameValue(..) => {
             if let (Some(feats), Some(gated_cfg)) = (features, GatedCfg::gate(cfg)) {
                 gated_cfg.check_and_emit(sess, feats);
             }
-            contains(&sess.config, cfg)
+            sess.config.contains(&(cfg.name(), cfg.value_str()))
         }
     }
 }
@@ -571,7 +553,7 @@ pub fn cfg_matches(cfg: &ast::MetaItem, sess: &ParseSess, features: Option<&Feat
 #[derive(RustcEncodable, RustcDecodable, Clone, Debug, PartialEq, Eq, Hash)]
 pub struct Stability {
     pub level: StabilityLevel,
-    pub feature: InternedString,
+    pub feature: Symbol,
     pub rustc_depr: Option<RustcDeprecation>,
 }
 
@@ -579,20 +561,20 @@ pub struct Stability {
 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Debug, Eq, Hash)]
 pub enum StabilityLevel {
     // Reason for the current stability level and the relevant rust-lang issue
-    Unstable { reason: Option<InternedString>, issue: u32 },
-    Stable { since: InternedString },
+    Unstable { reason: Option<Symbol>, issue: u32 },
+    Stable { since: Symbol },
 }
 
 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Debug, Eq, Hash)]
 pub struct RustcDeprecation {
-    pub since: InternedString,
-    pub reason: InternedString,
+    pub since: Symbol,
+    pub reason: Symbol,
 }
 
 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Debug, Eq, Hash)]
 pub struct Deprecation {
-    pub since: Option<InternedString>,
-    pub note: Option<InternedString>,
+    pub since: Option<Symbol>,
+    pub note: Option<Symbol>,
 }
 
 impl StabilityLevel {
@@ -611,7 +593,6 @@ fn find_stability_generic<'a, I>(diagnostic: &Handler,
 
     'outer: for attr in attrs_iter {
         let tag = attr.name();
-        let tag = &*tag;
         if tag != "rustc_deprecated" && tag != "unstable" && tag != "stable" {
             continue // not a stability level
         }
@@ -619,7 +600,7 @@ fn find_stability_generic<'a, I>(diagnostic: &Handler,
         mark_used(attr);
 
         if let Some(metas) = attr.meta_item_list() {
-            let get = |meta: &MetaItem, item: &mut Option<InternedString>| {
+            let get = |meta: &MetaItem, item: &mut Option<Symbol>| {
                 if item.is_some() {
                     handle_errors(diagnostic, meta.span, AttrError::MultipleItem(meta.name()));
                     return false
@@ -633,7 +614,7 @@ fn find_stability_generic<'a, I>(diagnostic: &Handler,
                 }
             };
 
-            match tag {
+            match &*tag.as_str() {
                 "rustc_deprecated" => {
                     if rustc_depr.is_some() {
                         span_err!(diagnostic, item_sp, E0540,
@@ -645,7 +626,7 @@ fn find_stability_generic<'a, I>(diagnostic: &Handler,
                     let mut reason = None;
                     for meta in metas {
                         if let Some(mi) = meta.meta_item() {
-                            match &*mi.name() {
+                            match &*mi.name().as_str() {
                                 "since" => if !get(mi, &mut since) { continue 'outer },
                                 "reason" => if !get(mi, &mut reason) { continue 'outer },
                                 _ => {
@@ -688,7 +669,7 @@ fn find_stability_generic<'a, I>(diagnostic: &Handler,
                     let mut issue = None;
                     for meta in metas {
                         if let Some(mi) = meta.meta_item() {
-                            match &*mi.name() {
+                            match &*mi.name().as_str() {
                                 "feature" => if !get(mi, &mut feature) { continue 'outer },
                                 "reason" => if !get(mi, &mut reason) { continue 'outer },
                                 "issue" => if !get(mi, &mut issue) { continue 'outer },
@@ -710,7 +691,7 @@ fn find_stability_generic<'a, I>(diagnostic: &Handler,
                                 level: Unstable {
                                     reason: reason,
                                     issue: {
-                                        if let Ok(issue) = issue.parse() {
+                                        if let Ok(issue) = issue.as_str().parse() {
                                             issue
                                         } else {
                                             span_err!(diagnostic, attr.span(), E0545,
@@ -743,7 +724,7 @@ fn find_stability_generic<'a, I>(diagnostic: &Handler,
                     let mut since = None;
                     for meta in metas {
                         if let NestedMetaItemKind::MetaItem(ref mi) = meta.node {
-                            match &*mi.name() {
+                            match &*mi.name().as_str() {
                                 "feature" => if !get(mi, &mut feature) { continue 'outer },
                                 "since" => if !get(mi, &mut since) { continue 'outer },
                                 _ => {
@@ -821,7 +802,7 @@ fn find_deprecation_generic<'a, I>(diagnostic: &Handler,
         }
 
         depr = if let Some(metas) = attr.meta_item_list() {
-            let get = |meta: &MetaItem, item: &mut Option<InternedString>| {
+            let get = |meta: &MetaItem, item: &mut Option<Symbol>| {
                 if item.is_some() {
                     handle_errors(diagnostic, meta.span, AttrError::MultipleItem(meta.name()));
                     return false
@@ -839,7 +820,7 @@ fn find_deprecation_generic<'a, I>(diagnostic: &Handler,
             let mut note = None;
             for meta in metas {
                 if let NestedMetaItemKind::MetaItem(ref mi) = meta.node {
-                    match &*mi.name() {
+                    match &*mi.name().as_str() {
                         "since" => if !get(mi, &mut since) { continue 'outer },
                         "note" => if !get(mi, &mut note) { continue 'outer },
                         _ => {
@@ -875,7 +856,7 @@ pub fn find_deprecation(diagnostic: &Handler, attrs: &[Attribute],
     find_deprecation_generic(diagnostic, attrs.iter(), item_sp)
 }
 
-pub fn require_unique_names(diagnostic: &Handler, metas: &[P<MetaItem>]) {
+pub fn require_unique_names(diagnostic: &Handler, metas: &[MetaItem]) {
     let mut set = HashSet::new();
     for meta in metas {
         let name = meta.name();
@@ -896,8 +877,8 @@ pub fn require_unique_names(diagnostic: &Handler, metas: &[P<MetaItem>]) {
 /// structure layout, and `packed` to remove padding.
 pub fn find_repr_attrs(diagnostic: &Handler, attr: &Attribute) -> Vec<ReprAttr> {
     let mut acc = Vec::new();
-    match attr.node.value.node {
-        ast::MetaItemKind::List(ref s, ref items) if s == "repr" => {
+    match attr.value.node {
+        ast::MetaItemKind::List(ref items) if attr.value.name == "repr" => {
             mark_used(attr);
             for item in items {
                 if !item.is_meta_item() {
@@ -906,7 +887,7 @@ pub fn find_repr_attrs(diagnostic: &Handler, attr: &Attribute) -> Vec<ReprAttr>
                 }
 
                 if let Some(mi) = item.word() {
-                    let word = &*mi.name();
+                    let word = &*mi.name().as_str();
                     let hint = match word {
                         // Can't use "extern" because it's not a lexical identifier.
                         "C" => Some(ReprExtern),

src/libsyntax/codemap.rs

@@ -871,6 +871,7 @@ impl CodeMapper for CodeMap {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use symbol::keywords;
     use std::rc::Rc;
 
     #[test]
@@ -1097,10 +1098,9 @@ mod tests {
     #[test]
     fn t11() {
         // Test span_to_expanded_string works with expansion
-        use ast::Name;
         let cm = init_code_map();
         let root = Span { lo: BytePos(0), hi: BytePos(11), expn_id: NO_EXPANSION };
-        let format = ExpnFormat::MacroBang(Name(0u32));
+        let format = ExpnFormat::MacroBang(keywords::Invalid.name());
         let callee = NameAndSpan { format: format,
                                    allow_internal_unstable: false,
                                    span: None };
@@ -1197,11 +1197,9 @@ mod tests {
     fn init_expansion_chain(cm: &CodeMap) -> Span {
         // Creates an expansion chain containing two recursive calls
         // root -> expA -> expA -> expB -> expB -> end
-        use ast::Name;
-
         let root = Span { lo: BytePos(0), hi: BytePos(11), expn_id: NO_EXPANSION };
 
-        let format_root = ExpnFormat::MacroBang(Name(0u32));
+        let format_root = ExpnFormat::MacroBang(keywords::Invalid.name());
         let callee_root = NameAndSpan { format: format_root,
                                         allow_internal_unstable: false,
                                         span: Some(root) };
@@ -1210,7 +1208,7 @@ mod tests {
         let id_a1 = cm.record_expansion(info_a1);
         let span_a1 = Span { lo: BytePos(12), hi: BytePos(23), expn_id: id_a1 };
 
-        let format_a = ExpnFormat::MacroBang(Name(1u32));
+        let format_a = ExpnFormat::MacroBang(keywords::As.name());
         let callee_a = NameAndSpan { format: format_a,
                                       allow_internal_unstable: false,
                                       span: Some(span_a1) };
@@ -1223,7 +1221,7 @@ mod tests {
         let id_b1 = cm.record_expansion(info_b1);
         let span_b1 = Span { lo: BytePos(25), hi: BytePos(36), expn_id: id_b1 };
 
-        let format_b = ExpnFormat::MacroBang(Name(2u32));
+        let format_b = ExpnFormat::MacroBang(keywords::Box.name());
         let callee_b = NameAndSpan { format: format_b,
                                      allow_internal_unstable: false,
                                      span: None };

src/libsyntax/config.rs

@@ -12,7 +12,7 @@ use attr::HasAttrs;
 use feature_gate::{feature_err, EXPLAIN_STMT_ATTR_SYNTAX, Features, get_features, GateIssue};
 use {fold, attr};
 use ast;
-use codemap::{Spanned, respan};
+use codemap::Spanned;
 use parse::ParseSess;
 use ptr::P;
 
@@ -106,12 +106,13 @@ impl<'a> StripUnconfigured<'a> {
         match (cfg.meta_item(), mi.meta_item()) {
             (Some(cfg), Some(mi)) =>
                 if cfg_matches(&cfg, self.sess, self.features) {
-                    self.process_cfg_attr(respan(mi.span, ast::Attribute_ {
+                    self.process_cfg_attr(ast::Attribute {
                         id: attr::mk_attr_id(),
-                        style: attr.node.style,
+                        style: attr.style,
                         value: mi.clone(),
                         is_sugared_doc: false,
-                    }))
+                        span: mi.span,
+                    })
                 } else {
                     None
                 },
@@ -131,8 +132,8 @@ impl<'a> StripUnconfigured<'a> {
                 return false;
             }
 
-            let mis = match attr.node.value.node {
-                ast::MetaItemKind::List(_, ref mis) if is_cfg(&attr) => mis,
+            let mis = match attr.value.node {
+                ast::MetaItemKind::List(ref mis) if is_cfg(&attr) => mis,
                 _ => return true
             };
 
@@ -160,7 +161,7 @@ impl<'a> StripUnconfigured<'a> {
                                           attr.span,
                                           GateIssue::Language,
                                           EXPLAIN_STMT_ATTR_SYNTAX);
-                if attr.node.is_sugared_doc {
+                if attr.is_sugared_doc {
                     err.help("`///` is for documentation comments. For a plain comment, use `//`.");
                 }
                 err.emit();

src/libsyntax/diagnostics/plugin.rs

@@ -19,6 +19,7 @@ use ext::base::{ExtCtxt, MacEager, MacResult};
 use ext::build::AstBuilder;
 use parse::token;
 use ptr::P;
+use symbol::Symbol;
 use tokenstream::{TokenTree};
 use util::small_vector::SmallVector;
 
@@ -141,7 +142,7 @@ pub fn expand_register_diagnostic<'cx>(ecx: &'cx mut ExtCtxt,
             ));
         }
     });
-    let sym = Ident::with_empty_ctxt(token::gensym(&format!(
+    let sym = Ident::with_empty_ctxt(Symbol::gensym(&format!(
         "__register_diagnostic_{}", code
     )));
     MacEager::items(SmallVector::many(vec![
@@ -194,11 +195,11 @@ pub fn expand_build_diagnostic_array<'cx>(ecx: &'cx mut ExtCtxt,
     let (count, expr) =
         with_registered_diagnostics(|diagnostics| {
             let descriptions: Vec<P<ast::Expr>> =
-                diagnostics.iter().filter_map(|(code, info)| {
+                diagnostics.iter().filter_map(|(&code, info)| {
                     info.description.map(|description| {
                         ecx.expr_tuple(span, vec![
-                            ecx.expr_str(span, code.as_str()),
-                            ecx.expr_str(span, description.as_str())
+                            ecx.expr_str(span, code),
+                            ecx.expr_str(span, description)
                         ])
                     })
                 }).collect();

src/libsyntax/entry.rs

@@ -28,7 +28,7 @@ pub fn entry_point_type(item: &Item, depth: usize) -> EntryPointType {
                 EntryPointType::Start
             } else if attr::contains_name(&item.attrs, "main") {
                 EntryPointType::MainAttr
-            } else if item.ident.name.as_str() == "main" {
+            } else if item.ident.name == "main" {
                 if depth == 1 {
                     // This is a top-level function so can be 'main'
                     EntryPointType::MainNamed