Merge pull request #1 from rust-lang/master

Merge upstream changes

5 files changed, 162 insertions, 161 deletions

diff --git a/src/libsyntax/parse/lexer/mod.rs b/src/libsyntax/parse/lexer/mod.rs
index 0e20eb49d39..068929c8948 100644
--- a/src/libsyntax/parse/lexer/mod.rs
+++ b/src/libsyntax/parse/lexer/mod.rs
@@ -14,7 +14,7 @@ use codemap::{CodeMap, FilePathMapping};
 use errors::{FatalError, DiagnosticBuilder};
 use parse::{token, ParseSess};
 use str::char_at;
-use symbol::Symbol;
+use symbol::{Symbol, keywords};
 use std_unicode::property::Pattern_White_Space;
 
 use std::borrow::Cow;
@@ -1115,26 +1115,53 @@ impl<'a> StringReader<'a> {
     /// token, and updates the interner
     fn next_token_inner(&mut self) -> Result<token::Token, ()> {
         let c = self.ch;
-        if ident_start(c) &&
-           match (c.unwrap(), self.nextch(), self.nextnextch()) {
-            // Note: r as in r" or r#" is part of a raw string literal,
-            // b as in b' is part of a byte literal.
-            // They are not identifiers, and are handled further down.
-            ('r', Some('"'), _) |
-            ('r', Some('#'), _) |
-            ('b', Some('"'), _) |
-            ('b', Some('\''), _) |
-            ('b', Some('r'), Some('"')) |
-            ('b', Some('r'), Some('#')) => false,
-            _ => true,
-        } {
-            let start = self.pos;
-            while ident_continue(self.ch) {
-                self.bump();
-            }
 
-            // FIXME: perform NFKC normalization here. (Issue #2253)
-            return Ok(self.with_str_from(start, |string| token::Ident(self.mk_ident(string))));
+        if ident_start(c) {
+            let (is_ident_start, is_raw_ident) =
+                match (c.unwrap(), self.nextch(), self.nextnextch()) {
+                    // r# followed by an identifier starter is a raw identifier.
+                    // This is an exception to the r# case below.
+                    ('r', Some('#'), x) if ident_start(x) => (true, true),
+                    // r as in r" or r#" is part of a raw string literal.
+                    // b as in b' is part of a byte literal.
+                    // They are not identifiers, and are handled further down.
+                    ('r', Some('"'), _) |
+                    ('r', Some('#'), _) |
+                    ('b', Some('"'), _) |
+                    ('b', Some('\''), _) |
+                    ('b', Some('r'), Some('"')) |
+                    ('b', Some('r'), Some('#')) => (false, false),
+                    _ => (true, false),
+                };
+            if is_ident_start {
+                let raw_start = self.pos;
+                if is_raw_ident {
+                    // Consume the 'r#' characters.
+                    self.bump();
+                    self.bump();
+                }
+
+                let start = self.pos;
+                while ident_continue(self.ch) {
+                    self.bump();
+                }
+
+                return Ok(self.with_str_from(start, |string| {
+                    // FIXME: perform NFKC normalization here. (Issue #2253)
+                    let ident = self.mk_ident(string);
+                    if is_raw_ident && (token::is_path_segment_keyword(ident) ||
+                                        ident.name == keywords::Underscore.name()) {
+                        self.fatal_span_(raw_start, self.pos,
+                            &format!("`r#{}` is not currently supported.", ident.name)
+                        ).raise();
+                    }
+                    if is_raw_ident {
+                        let span = self.mk_sp(raw_start, self.pos);
+                        self.sess.raw_identifier_spans.borrow_mut().push(span);
+                    }
+                    token::Ident(ident, is_raw_ident)
+                }));
+            }
         }
 
         if is_dec_digit(c) {
@@ -1773,6 +1800,7 @@ mod tests {
             included_mod_stack: RefCell::new(Vec::new()),
             code_map: cm,
             missing_fragment_specifiers: RefCell::new(HashSet::new()),
+            raw_identifier_spans: RefCell::new(Vec::new()),
             registered_diagnostics: Lock::new(ErrorMap::new()),
             non_modrs_mods: RefCell::new(vec![]),
         }
@@ -1801,7 +1829,7 @@ mod tests {
             assert_eq!(string_reader.next_token().tok, token::Whitespace);
             let tok1 = string_reader.next_token();
             let tok2 = TokenAndSpan {
-                tok: token::Ident(id),
+                tok: token::Ident(id, false),
                 sp: Span::new(BytePos(21), BytePos(23), NO_EXPANSION),
             };
             assert_eq!(tok1, tok2);
@@ -1811,7 +1839,7 @@ mod tests {
             // read another token:
             let tok3 = string_reader.next_token();
             let tok4 = TokenAndSpan {
-                tok: token::Ident(Ident::from_str("main")),
+                tok: mk_ident("main"),
                 sp: Span::new(BytePos(24), BytePos(28), NO_EXPANSION),
             };
             assert_eq!(tok3, tok4);
@@ -1830,7 +1858,7 @@ mod tests {
 
     // make the identifier by looking up the string in the interner
     fn mk_ident(id: &str) -> token::Token {
-        token::Ident(Ident::from_str(id))
+        token::Token::from_ast_ident(Ident::from_str(id))
     }
 
     #[test]
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index f7e5d40b524..1483691a1ea 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -40,7 +40,6 @@ pub mod attr;
 
 pub mod common;
 pub mod classify;
-pub mod obsolete;
 
 /// Info about a parsing session.
 pub struct ParseSess {
@@ -48,6 +47,9 @@ pub struct ParseSess {
     pub unstable_features: UnstableFeatures,
     pub config: CrateConfig,
     pub missing_fragment_specifiers: RefCell<HashSet<Span>>,
+    /// Places where raw identifiers were used. This is used for feature gating
+    /// raw identifiers
+    pub raw_identifier_spans: RefCell<Vec<Span>>,
     /// The registered diagnostics codes
     pub registered_diagnostics: Lock<ErrorMap>,
     // Spans where a `mod foo;` statement was included in a non-mod.rs file.
@@ -74,6 +76,7 @@ impl ParseSess {
             unstable_features: UnstableFeatures::from_environment(),
             config: HashSet::new(),
             missing_fragment_specifiers: RefCell::new(HashSet::new()),
+            raw_identifier_spans: RefCell::new(Vec::new()),
             registered_diagnostics: Lock::new(ErrorMap::new()),
             included_mod_stack: RefCell::new(vec![]),
             code_map,
@@ -298,7 +301,6 @@ pub fn str_lit(lit: &str, diag: Option<(Span, &Handler)>) -> String {
     debug!("parse_str_lit: given {}", escape_default(lit));
     let mut res = String::with_capacity(lit.len());
 
-    // FIXME #8372: This could be a for-loop if it didn't borrow the iterator
     let error = |i| format!("lexer should have rejected {} at {}", lit, i);
 
     /// Eat everything up to a non-whitespace
@@ -503,7 +505,6 @@ pub fn byte_lit(lit: &str) -> (u8, usize) {
 pub fn byte_str_lit(lit: &str) -> Lrc<Vec<u8>> {
     let mut res = Vec::with_capacity(lit.len());
 
-    // FIXME #8372: This could be a for-loop if it didn't borrow the iterator
     let error = |i| format!("lexer should have rejected {} at {}", lit, i);
 
     /// Eat everything up to a non-whitespace
@@ -741,9 +742,9 @@ mod tests {
             match (tts.len(), tts.get(0), tts.get(1), tts.get(2), tts.get(3)) {
                 (
                     4,
-                    Some(&TokenTree::Token(_, token::Ident(name_macro_rules))),
+                    Some(&TokenTree::Token(_, token::Ident(name_macro_rules, false))),
                     Some(&TokenTree::Token(_, token::Not)),
-                    Some(&TokenTree::Token(_, token::Ident(name_zip))),
+                    Some(&TokenTree::Token(_, token::Ident(name_zip, false))),
                     Some(&TokenTree::Delimited(_, ref macro_delimed)),
                 )
                 if name_macro_rules.name == "macro_rules"
@@ -762,7 +763,7 @@ mod tests {
                                 (
                                     2,
                                     Some(&TokenTree::Token(_, token::Dollar)),
-                                    Some(&TokenTree::Token(_, token::Ident(ident))),
+                                    Some(&TokenTree::Token(_, token::Ident(ident, false))),
                                 )
                                 if first_delimed.delim == token::Paren && ident.name == "a" => {},
                                 _ => panic!("value 3: {:?}", *first_delimed),
@@ -772,7 +773,7 @@ mod tests {
                                 (
                                     2,
                                     Some(&TokenTree::Token(_, token::Dollar)),
-                                    Some(&TokenTree::Token(_, token::Ident(ident))),
+                                    Some(&TokenTree::Token(_, token::Ident(ident, false))),
                                 )
                                 if second_delimed.delim == token::Paren
                                 && ident.name == "a" => {},
@@ -793,17 +794,18 @@ mod tests {
             let tts = string_to_stream("fn a (b : i32) { b; }".to_string());
 
             let expected = TokenStream::concat(vec![
-                TokenTree::Token(sp(0, 2), token::Ident(Ident::from_str("fn"))).into(),
-                TokenTree::Token(sp(3, 4), token::Ident(Ident::from_str("a"))).into(),
+                TokenTree::Token(sp(0, 2), token::Ident(Ident::from_str("fn"), false)).into(),
+                TokenTree::Token(sp(3, 4), token::Ident(Ident::from_str("a"), false)).into(),
                 TokenTree::Delimited(
                     sp(5, 14),
                     tokenstream::Delimited {
                         delim: token::DelimToken::Paren,
                         tts: TokenStream::concat(vec![
-                            TokenTree::Token(sp(6, 7), token::Ident(Ident::from_str("b"))).into(),
+                            TokenTree::Token(sp(6, 7),
+                                             token::Ident(Ident::from_str("b"), false)).into(),
                             TokenTree::Token(sp(8, 9), token::Colon).into(),
                             TokenTree::Token(sp(10, 13),
-                                             token::Ident(Ident::from_str("i32"))).into(),
+                                             token::Ident(Ident::from_str("i32"), false)).into(),
                         ]).into(),
                     }).into(),
                 TokenTree::Delimited(
@@ -811,7 +813,8 @@ mod tests {
                     tokenstream::Delimited {
                         delim: token::DelimToken::Brace,
                         tts: TokenStream::concat(vec![
-                            TokenTree::Token(sp(17, 18), token::Ident(Ident::from_str("b"))).into(),
+                            TokenTree::Token(sp(17, 18),
+                                             token::Ident(Ident::from_str("b"), false)).into(),
                             TokenTree::Token(sp(18, 19), token::Semi).into(),
                         ]).into(),
                     }).into()
diff --git a/src/libsyntax/parse/obsolete.rs b/src/libsyntax/parse/obsolete.rs
deleted file mode 100644
index 49a697edf41..00000000000
--- a/src/libsyntax/parse/obsolete.rs
+++ /dev/null
@@ -1,67 +0,0 @@
-// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-//! Support for parsing unsupported, old syntaxes, for the purpose of reporting errors. Parsing of
-//! these syntaxes is tested by compile-test/obsolete-syntax.rs.
-//!
-//! Obsolete syntax that becomes too hard to parse can be removed.
-
-use syntax_pos::Span;
-use parse::parser;
-
-/// The specific types of unsupported syntax
-#[derive(Copy, Clone, PartialEq, Eq, Hash)]
-pub enum ObsoleteSyntax {
-    // Nothing here at the moment
-}
-
-pub trait ParserObsoleteMethods {
-    /// Reports an obsolete syntax non-fatal error.
-    fn obsolete(&mut self, sp: Span, kind: ObsoleteSyntax);
-    fn report(&mut self,
-              sp: Span,
-              kind: ObsoleteSyntax,
-              kind_str: &str,
-              desc: &str,
-              error: bool);
-}
-
-impl<'a> ParserObsoleteMethods for parser::Parser<'a> {
-    /// Reports an obsolete syntax non-fatal error.
-    #[allow(unused_variables)]
-    #[allow(unreachable_code)]
-    fn obsolete(&mut self, sp: Span, kind: ObsoleteSyntax) {
-        let (kind_str, desc, error) = match kind {
-            // Nothing here at the moment
-        };
-
-        self.report(sp, kind, kind_str, desc, error);
-    }
-
-    fn report(&mut self,
-              sp: Span,
-              kind: ObsoleteSyntax,
-              kind_str: &str,
-              desc: &str,
-              error: bool) {
-        let mut err = if error {
-            self.diagnostic().struct_span_err(sp, &format!("obsolete syntax: {}", kind_str))
-        } else {
-            self.diagnostic().struct_span_warn(sp, &format!("obsolete syntax: {}", kind_str))
-        };
-
-        if !self.obsolete_set.contains(&kind) &&
-            (error || self.sess.span_diagnostic.flags.can_emit_warnings) {
-            err.note(desc);
-            self.obsolete_set.insert(kind);
-        }
-        err.emit();
-    }
-}
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 6d8975197d5..f5ab023b30e 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -48,7 +48,6 @@ use parse::{self, classify, token};
 use parse::common::SeqSep;
 use parse::lexer::TokenAndSpan;
 use parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
-use parse::obsolete::ObsoleteSyntax;
 use parse::{new_sub_parser_from_file, ParseSess, Directory, DirectoryOwnership};
 use util::parser::{AssocOp, Fixity};
 use print::pprust;
@@ -59,7 +58,6 @@ use symbol::{Symbol, keywords};
 use util::ThinVec;
 
 use std::cmp;
-use std::collections::HashSet;
 use std::mem;
 use std::path::{self, Path, PathBuf};
 use std::slice;
@@ -229,9 +227,6 @@ pub struct Parser<'a> {
     /// the previous token kind
     prev_token_kind: PrevTokenKind,
     pub restrictions: Restrictions,
-    /// The set of seen errors about obsolete syntax. Used to suppress
-    /// extra detail when the same error is seen twice
-    pub obsolete_set: HashSet<ObsoleteSyntax>,
     /// Used to determine the path to externally loaded source files
     pub directory: Directory,
     /// Whether to parse sub-modules in other files.
@@ -358,7 +353,7 @@ impl TokenCursor {
 
         let body = TokenTree::Delimited(sp, Delimited {
             delim: token::Bracket,
-            tts: [TokenTree::Token(sp, token::Ident(ast::Ident::from_str("doc"))),
+            tts: [TokenTree::Token(sp, token::Ident(ast::Ident::from_str("doc"), false)),
                   TokenTree::Token(sp, token::Eq),
                   TokenTree::Token(sp, token::Literal(
                       token::StrRaw(Symbol::intern(&stripped), num_of_hashes), None))]
@@ -460,7 +455,7 @@ impl Error {
                                            ref dir_path } => {
                 let mut err = struct_span_err!(handler, sp, E0583,
                                                "file not found for module `{}`", mod_name);
-                err.help(&format!("name the file either {} or {} inside the directory {:?}",
+                err.help(&format!("name the file either {} or {} inside the directory \"{}\"",
                                   default_path,
                                   secondary_path,
                                   dir_path));
@@ -555,7 +550,6 @@ impl<'a> Parser<'a> {
             meta_var_span: None,
             prev_token_kind: PrevTokenKind::Other,
             restrictions: Restrictions::empty(),
-            obsolete_set: HashSet::new(),
             recurse_into_file_modules,
             directory: Directory {
                 path: PathBuf::new(),
@@ -784,7 +778,7 @@ impl<'a> Parser<'a> {
 
     fn parse_ident_common(&mut self, recover: bool) -> PResult<'a, ast::Ident> {
         match self.token {
-            token::Ident(i) => {
+            token::Ident(i, _) => {
                 if self.token.is_reserved_ident() {
                     let mut err = self.expected_ident_found();
                     if recover {
@@ -1925,7 +1919,7 @@ impl<'a> Parser<'a> {
 
     pub fn parse_path_segment_ident(&mut self) -> PResult<'a, ast::Ident> {
         match self.token {
-            token::Ident(sid) if self.token.is_path_segment_keyword() => {
+            token::Ident(sid, _) if self.token.is_path_segment_keyword() => {
                 self.bump();
                 Ok(sid)
             }
@@ -2740,11 +2734,14 @@ impl<'a> Parser<'a> {
     }
 
     pub fn process_potential_macro_variable(&mut self) {
-        let ident = match self.token {
+        let (ident, is_raw) = match self.token {
             token::Dollar if self.span.ctxt() != syntax_pos::hygiene::SyntaxContext::empty() &&
                              self.look_ahead(1, |t| t.is_ident()) => {
                 self.bump();
-                let name = match self.token { token::Ident(ident) => ident, _ => unreachable!() };
+                let name = match self.token {
+                    token::Ident(ident, _) => ident,
+                    _ => unreachable!()
+                };
                 let mut err = self.fatal(&format!("unknown macro variable `{}`", name));
                 err.span_label(self.span, "unknown macro variable");
                 err.emit();
@@ -2753,13 +2750,13 @@ impl<'a> Parser<'a> {
             token::Interpolated(ref nt) => {
                 self.meta_var_span = Some(self.span);
                 match nt.0 {
-                    token::NtIdent(ident) => ident,
+                    token::NtIdent(ident, is_raw) => (ident, is_raw),
                     _ => return,
                 }
             }
             _ => return,
         };
-        self.token = token::Ident(ident.node);
+        self.token = token::Ident(ident.node, is_raw);
         self.span = ident.span;
     }
 
@@ -2853,17 +2850,6 @@ impl<'a> Parser<'a> {
                 let (span, e) = self.interpolated_or_expr_span(e)?;
                 (lo.to(span), ExprKind::AddrOf(m, e))
             }
-            token::Ident(..) if self.token.is_keyword(keywords::In) => {
-                self.bump();
-                let place = self.parse_expr_res(
-                    Restrictions::NO_STRUCT_LITERAL,
-                    None,
-                )?;
-                let blk = self.parse_block()?;
-                let span = blk.span;
-                let blk_expr = self.mk_expr(span, ExprKind::Block(blk), ThinVec::new());
-                (lo.to(span), ExprKind::InPlace(place, blk_expr))
-            }
             token::Ident(..) if self.token.is_keyword(keywords::Box) => {
                 self.bump();
                 let e = self.parse_prefix_expr(None);
@@ -3026,8 +3012,6 @@ impl<'a> Parser<'a> {
                 }
                 AssocOp::Assign =>
                     self.mk_expr(span, ExprKind::Assign(lhs, rhs), ThinVec::new()),
-                AssocOp::Inplace =>
-                    self.mk_expr(span, ExprKind::InPlace(lhs, rhs), ThinVec::new()),
                 AssocOp::AssignOp(k) => {
                     let aop = match k {
                         token::Plus =>    BinOpKind::Add,
@@ -3672,7 +3656,13 @@ impl<'a> Parser<'a> {
                 if self.token != token::CloseDelim(token::Brace) {
                     let token_str = self.this_token_to_string();
                     let mut err = self.fatal(&format!("expected `{}`, found `{}`", "}", token_str));
-                    err.span_label(self.span, "expected `}`");
+                    if self.token == token::Comma { // Issue #49257
+                        err.span_label(self.span,
+                                       "`..` must be in the last position, \
+                                        and cannot have a trailing comma");
+                    } else {
+                        err.span_label(self.span, "expected `}`");
+                    }
                     return Err(err);
                 }
                 etc = true;
@@ -4245,7 +4235,7 @@ impl<'a> Parser<'a> {
                      -> PResult<'a, Option<P<Item>>> {
         let token_lo = self.span;
         let (ident, def) = match self.token {
-            token::Ident(ident) if ident.name == keywords::Macro.name() => {
+            token::Ident(ident, false) if ident.name == keywords::Macro.name() => {
                 self.bump();
                 let ident = self.parse_ident()?;
                 let tokens = if self.check(&token::OpenDelim(token::Brace)) {
@@ -4273,7 +4263,7 @@ impl<'a> Parser<'a> {
 
                 (ident, ast::MacroDef { tokens: tokens.into(), legacy: false })
             }
-            token::Ident(ident) if ident.name == "macro_rules" &&
+            token::Ident(ident, _) if ident.name == "macro_rules" &&
                                    self.look_ahead(1, |t| *t == token::Not) => {
                 let prev_span = self.prev_span;
                 self.complain_if_pub_macro(&vis.node, prev_span);
@@ -4598,6 +4588,9 @@ impl<'a> Parser<'a> {
 
     /// Parse a statement, including the trailing semicolon.
     pub fn parse_full_stmt(&mut self, macro_legacy_warnings: bool) -> PResult<'a, Option<Stmt>> {
+        // skip looking for a trailing semicolon when we have an interpolated statement
+        maybe_whole!(self, NtStmt, |x| Some(x));
+
         let mut stmt = match self.parse_stmt_without_recovery(macro_legacy_warnings)? {
             Some(stmt) => stmt,
             None => return Ok(None),
@@ -5078,7 +5071,9 @@ impl<'a> Parser<'a> {
     fn parse_self_arg(&mut self) -> PResult<'a, Option<Arg>> {
         let expect_ident = |this: &mut Self| match this.token {
             // Preserve hygienic context.
-            token::Ident(ident) => { let sp = this.span; this.bump(); codemap::respan(sp, ident) }
+            token::Ident(ident, _) => {
+                let sp = this.span; this.bump(); codemap::respan(sp, ident)
+            }
             _ => unreachable!()
         };
         let isolated_self = |this: &mut Self, n| {
@@ -5375,7 +5370,7 @@ impl<'a> Parser<'a> {
             VisibilityKind::Inherited => Ok(()),
             _ => {
                 let is_macro_rules: bool = match self.token {
-                    token::Ident(sid) => sid.name == Symbol::intern("macro_rules"),
+                    token::Ident(sid, _) => sid.name == Symbol::intern("macro_rules"),
                     _ => false,
                 };
                 if is_macro_rules {
@@ -7016,7 +7011,7 @@ impl<'a> Parser<'a> {
     fn parse_rename(&mut self) -> PResult<'a, Option<Ident>> {
         if self.eat_keyword(keywords::As) {
             match self.token {
-                token::Ident(ident) if ident.name == keywords::Underscore.name() => {
+                token::Ident(ident, false) if ident.name == keywords::Underscore.name() => {
                     self.bump(); // `_`
                     Ok(Some(Ident { name: ident.name.gensymed(), ..ident }))
                 }
diff --git a/src/libsyntax/parse/token.rs b/src/libsyntax/parse/token.rs
index 4ada9e20f2c..e2dfca5d10a 100644
--- a/src/libsyntax/parse/token.rs
+++ b/src/libsyntax/parse/token.rs
@@ -91,8 +91,8 @@ impl Lit {
     }
 }
 
-fn ident_can_begin_expr(ident: ast::Ident) -> bool {
-    let ident_token: Token = Ident(ident);
+fn ident_can_begin_expr(ident: ast::Ident, is_raw: bool) -> bool {
+    let ident_token: Token = Ident(ident, is_raw);
 
     !ident_token.is_reserved_ident() ||
     ident_token.is_path_segment_keyword() ||
@@ -116,8 +116,8 @@ fn ident_can_begin_expr(ident: ast::Ident) -> bool {
     ].contains(&ident.name)
 }
 
-fn ident_can_begin_type(ident: ast::Ident) -> bool {
-    let ident_token: Token = Ident(ident);
+fn ident_can_begin_type(ident: ast::Ident, is_raw: bool) -> bool {
+    let ident_token: Token = Ident(ident, is_raw);
 
     !ident_token.is_reserved_ident() ||
     ident_token.is_path_segment_keyword() ||
@@ -132,6 +132,44 @@ fn ident_can_begin_type(ident: ast::Ident) -> bool {
     ].contains(&ident.name)
 }
 
+pub fn is_path_segment_keyword(id: ast::Ident) -> bool {
+    id.name == keywords::Super.name() ||
+    id.name == keywords::SelfValue.name() ||
+    id.name == keywords::SelfType.name() ||
+    id.name == keywords::Extern.name() ||
+    id.name == keywords::Crate.name() ||
+    id.name == keywords::CrateRoot.name() ||
+    id.name == keywords::DollarCrate.name()
+}
+
+// We see this identifier in a normal identifier position, like variable name or a type.
+// How was it written originally? Did it use the raw form? Let's try to guess.
+pub fn is_raw_guess(ident: ast::Ident) -> bool {
+    ident.name != keywords::Invalid.name() &&
+    is_reserved_ident(ident) && !is_path_segment_keyword(ident)
+}
+
+// Returns true for reserved identifiers used internally for elided lifetimes,
+// unnamed method parameters, crate root module, error recovery etc.
+pub fn is_special_ident(id: ast::Ident) -> bool {
+    id.name <= keywords::Underscore.name()
+}
+
+/// Returns `true` if the token is a keyword used in the language.
+pub fn is_used_keyword(id: ast::Ident) -> bool {
+    id.name >= keywords::As.name() && id.name <= keywords::While.name()
+}
+
+/// Returns `true` if the token is a keyword reserved for possible future use.
+pub fn is_unused_keyword(id: ast::Ident) -> bool {
+    id.name >= keywords::Abstract.name() && id.name <= keywords::Yield.name()
+}
+
+/// Returns `true` if the token is either a special identifier or a keyword.
+pub fn is_reserved_ident(id: ast::Ident) -> bool {
+    is_special_ident(id) || is_used_keyword(id) || is_unused_keyword(id)
+}
+
 #[derive(Clone, RustcEncodable, RustcDecodable, PartialEq, Eq, Hash, Debug)]
 pub enum Token {
     /* Expression-operator symbols. */
@@ -175,7 +213,7 @@ pub enum Token {
     Literal(Lit, Option<ast::Name>),
 
     /* Name components */
-    Ident(ast::Ident),
+    Ident(ast::Ident, /* is_raw */ bool),
     Lifetime(ast::Ident),
 
     // The `LazyTokenStream` is a pure function of the `Nonterminal`,
@@ -203,6 +241,11 @@ impl Token {
         Token::Interpolated(Lrc::new((nt, LazyTokenStream::new())))
     }
 
+    /// Recovers a `Token` from an `ast::Ident`. This creates a raw identifier if necessary.
+    pub fn from_ast_ident(ident: ast::Ident) -> Token {
+        Ident(ident, is_raw_guess(ident))
+    }
+
     /// Returns `true` if the token starts with '>'.
     pub fn is_like_gt(&self) -> bool {
         match *self {
@@ -214,7 +257,8 @@ impl Token {
     /// Returns `true` if the token can appear at the start of an expression.
     pub fn can_begin_expr(&self) -> bool {
         match *self {
-            Ident(ident)                => ident_can_begin_expr(ident), // value name or keyword
+            Ident(ident, is_raw)              =>
+                ident_can_begin_expr(ident, is_raw), // value name or keyword
             OpenDelim(..)                     | // tuple, array or block
             Literal(..)                       | // literal
             Not                               | // operator not
@@ -239,7 +283,8 @@ impl Token {
     /// Returns `true` if the token can appear at the start of a type.
     pub fn can_begin_type(&self) -> bool {
         match *self {
-            Ident(ident)                => ident_can_begin_type(ident), // type name or keyword
+            Ident(ident, is_raw)        =>
+                ident_can_begin_type(ident, is_raw), // type name or keyword
             OpenDelim(Paren)            | // tuple
             OpenDelim(Bracket)          | // array
             Not                         | // never
@@ -272,11 +317,11 @@ impl Token {
         }
     }
 
-    pub fn ident(&self) -> Option<ast::Ident> {
+    pub fn ident(&self) -> Option<(ast::Ident, bool)> {
         match *self {
-            Ident(ident) => Some(ident),
+            Ident(ident, is_raw) => Some((ident, is_raw)),
             Interpolated(ref nt) => match nt.0 {
-                NtIdent(ident) => Some(ident.node),
+                NtIdent(ident, is_raw) => Some((ident.node, is_raw)),
                 _ => None,
             },
             _ => None,
@@ -351,19 +396,13 @@ impl Token {
 
     /// Returns `true` if the token is a given keyword, `kw`.
     pub fn is_keyword(&self, kw: keywords::Keyword) -> bool {
-        self.ident().map(|ident| ident.name == kw.name()).unwrap_or(false)
+        self.ident().map(|(ident, is_raw)| ident.name == kw.name() && !is_raw).unwrap_or(false)
     }
 
     pub fn is_path_segment_keyword(&self) -> bool {
         match self.ident() {
-            Some(id) => id.name == keywords::Super.name() ||
-                        id.name == keywords::SelfValue.name() ||
-                        id.name == keywords::SelfType.name() ||
-                        id.name == keywords::Extern.name() ||
-                        id.name == keywords::Crate.name() ||
-                        id.name == keywords::CrateRoot.name() ||
-                        id.name == keywords::DollarCrate.name(),
-            None => false,
+            Some((id, false)) => is_path_segment_keyword(id),
+            _ => false,
         }
     }
 
@@ -371,7 +410,7 @@ impl Token {
     // unnamed method parameters, crate root module, error recovery etc.
     pub fn is_special_ident(&self) -> bool {
         match self.ident() {
-            Some(id) => id.name <= keywords::Underscore.name(),
+            Some((id, false)) => is_special_ident(id),
             _ => false,
         }
     }
@@ -379,7 +418,7 @@ impl Token {
     /// Returns `true` if the token is a keyword used in the language.
     pub fn is_used_keyword(&self) -> bool {
         match self.ident() {
-            Some(id) => id.name >= keywords::As.name() && id.name <= keywords::While.name(),
+            Some((id, false)) => is_used_keyword(id),
             _ => false,
         }
     }
@@ -387,7 +426,7 @@ impl Token {
     /// Returns `true` if the token is a keyword reserved for possible future use.
     pub fn is_unused_keyword(&self) -> bool {
         match self.ident() {
-            Some(id) => id.name >= keywords::Abstract.name() && id.name <= keywords::Yield.name(),
+            Some((id, false)) => is_unused_keyword(id),
             _ => false,
         }
     }
@@ -460,7 +499,10 @@ impl Token {
 
     /// Returns `true` if the token is either a special identifier or a keyword.
     pub fn is_reserved_ident(&self) -> bool {
-        self.is_special_ident() || self.is_used_keyword() || self.is_unused_keyword()
+        match self.ident() {
+            Some((id, false)) => is_reserved_ident(id),
+            _ => false,
+        }
     }
 
     pub fn interpolated_to_tokenstream(&self, sess: &ParseSess, span: Span)
@@ -496,8 +538,8 @@ impl Token {
             Nonterminal::NtImplItem(ref item) => {
                 tokens = prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span);
             }
-            Nonterminal::NtIdent(ident) => {
-                let token = Token::Ident(ident.node);
+            Nonterminal::NtIdent(ident, is_raw) => {
+                let token = Token::Ident(ident.node, is_raw);
                 tokens = Some(TokenTree::Token(ident.span, token).into());
             }
             Nonterminal::NtLifetime(lifetime) => {
@@ -529,7 +571,7 @@ pub enum Nonterminal {
     NtPat(P<ast::Pat>),
     NtExpr(P<ast::Expr>),
     NtTy(P<ast::Ty>),
-    NtIdent(ast::SpannedIdent),
+    NtIdent(ast::SpannedIdent, /* is_raw */ bool),
     /// Stuff inside brackets for attributes
     NtMeta(ast::MetaItem),
     NtPath(ast::Path),