rollup merge of #24487: erickt/syntax

This removes the usage of `#[feature(into_cow, slice_patterns, box_syntax, box_patterns, quote, unsafe_destructor)]` from being used in libsyntax. My main desire for this is that it brings me one step closer to letting [syntex](https://github.com/erickt/rust-syntex) compile with stable rust. Hopefully this doesn't inconvenience rust development.

4 files changed, 78 insertions, 54 deletions

diff --git a/src/libsyntax/parse/lexer/comments.rs b/src/libsyntax/parse/lexer/comments.rs
index bda01d5a654..fb3a96f4c28 100644
--- a/src/libsyntax/parse/lexer/comments.rs
+++ b/src/libsyntax/parse/lexer/comments.rs
@@ -13,11 +13,12 @@ pub use self::CommentStyle::*;
 use ast;
 use codemap::{BytePos, CharPos, CodeMap, Pos};
 use diagnostic;
-use parse::lexer::{is_whitespace, Reader};
-use parse::lexer::{StringReader, TokenAndSpan};
 use parse::lexer::is_block_doc_comment;
+use parse::lexer::{StringReader, TokenAndSpan};
+use parse::lexer::{is_whitespace, Reader};
 use parse::lexer;
 use print::pprust;
+use str::char_at;
 
 use std::io::Read;
 use std::usize;
@@ -209,7 +210,7 @@ fn all_whitespace(s: &str, col: CharPos) -> Option<usize> {
     let mut col = col.to_usize();
     let mut cursor: usize = 0;
     while col > 0 && cursor < len {
-        let ch = s.char_at(cursor);
+        let ch = char_at(s, cursor);
         if !ch.is_whitespace() {
             return None;
         }
@@ -246,7 +247,7 @@ fn read_block_comment(rdr: &mut StringReader,
     rdr.bump();
     rdr.bump();
 
-    let mut curr_line = String::from_str("/*");
+    let mut curr_line = String::from("/*");
 
     // doc-comments are not really comments, they are attributes
     if (rdr.curr_is('*') && !rdr.nextch_is('*')) || rdr.curr_is('!') {
diff --git a/src/libsyntax/parse/lexer/mod.rs b/src/libsyntax/parse/lexer/mod.rs
index f891318659a..8e37b983e21 100644
--- a/src/libsyntax/parse/lexer/mod.rs
+++ b/src/libsyntax/parse/lexer/mod.rs
@@ -13,10 +13,11 @@ use codemap::{BytePos, CharPos, CodeMap, Pos, Span};
 use codemap;
 use diagnostic::SpanHandler;
 use ext::tt::transcribe::tt_next_token;
-use parse::token;
 use parse::token::str_to_ident;
+use parse::token;
+use str::char_at;
 
-use std::borrow::{IntoCow, Cow};
+use std::borrow::Cow;
 use std::char;
 use std::fmt;
 use std::mem::replace;
@@ -289,11 +290,11 @@ impl<'a> StringReader<'a> {
                           s: &'b str, errmsg: &'b str) -> Cow<'b, str> {
         let mut i = 0;
         while i < s.len() {
-            let ch = s.char_at(i);
+            let ch = char_at(s, i);
             let next = i + ch.len_utf8();
             if ch == '\r' {
-                if next < s.len() && s.char_at(next) == '\n' {
-                    return translate_crlf_(self, start, s, errmsg, i).into_cow();
+                if next < s.len() && char_at(s, next) == '\n' {
+                    return translate_crlf_(self, start, s, errmsg, i).into();
                 }
                 let pos = start + BytePos(i as u32);
                 let end_pos = start + BytePos(next as u32);
@@ -301,19 +302,19 @@ impl<'a> StringReader<'a> {
             }
             i = next;
         }
-        return s.into_cow();
+        return s.into();
 
         fn translate_crlf_(rdr: &StringReader, start: BytePos,
                         s: &str, errmsg: &str, mut i: usize) -> String {
             let mut buf = String::with_capacity(s.len());
             let mut j = 0;
             while i < s.len() {
-                let ch = s.char_at(i);
+                let ch = char_at(s, i);
                 let next = i + ch.len_utf8();
                 if ch == '\r' {
                     if j < i { buf.push_str(&s[j..i]); }
                     j = next;
-                    if next >= s.len() || s.char_at(next) != '\n' {
+                    if next >= s.len() || char_at(s, next) != '\n' {
                         let pos = start + BytePos(i as u32);
                         let end_pos = start + BytePos(next as u32);
                         rdr.err_span_(pos, end_pos, errmsg);
@@ -335,7 +336,7 @@ impl<'a> StringReader<'a> {
         if current_byte_offset < self.source_text.len() {
             assert!(self.curr.is_some());
             let last_char = self.curr.unwrap();
-            let ch = self.source_text.char_at(current_byte_offset);
+            let ch = char_at(&self.source_text, current_byte_offset);
             let next = current_byte_offset + ch.len_utf8();
             let byte_offset_diff = next - current_byte_offset;
             self.pos = self.pos + Pos::from_usize(byte_offset_diff);
@@ -357,7 +358,7 @@ impl<'a> StringReader<'a> {
     pub fn nextch(&self) -> Option<char> {
         let offset = self.byte_offset(self.pos).to_usize();
         if offset < self.source_text.len() {
-            Some(self.source_text.char_at(offset))
+            Some(char_at(&self.source_text, offset))
         } else {
             None
         }
@@ -371,9 +372,9 @@ impl<'a> StringReader<'a> {
         let offset = self.byte_offset(self.pos).to_usize();
         let s = &self.source_text[..];
         if offset >= s.len() { return None }
-        let next = offset + s.char_at(offset).len_utf8();
+        let next = offset + char_at(s, offset).len_utf8();
         if next < s.len() {
-            Some(s.char_at(next))
+            Some(char_at(s, next))
         } else {
             None
         }
@@ -564,7 +565,7 @@ impl<'a> StringReader<'a> {
                 let string = if has_cr {
                     self.translate_crlf(start_bpos, string,
                                         "bare CR not allowed in block doc-comment")
-                } else { string.into_cow() };
+                } else { string.into() };
                 token::DocComment(token::intern(&string[..]))
             } else {
                 token::Comment
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index 4b7b7b66582..1333e27058f 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -16,7 +16,7 @@ use diagnostic::{SpanHandler, mk_span_handler, default_handler, Auto, FatalError
 use parse::attr::ParserAttr;
 use parse::parser::Parser;
 use ptr::P;
-
+use str::char_at;
 
 use std::cell::{Cell, RefCell};
 use std::fs::File;
@@ -288,7 +288,7 @@ pub fn filemap_to_tts(sess: &ParseSess, filemap: Rc<FileMap>)
     // parsing tt's probably shouldn't require a parser at all.
     let cfg = Vec::new();
     let srdr = lexer::StringReader::new(&sess.span_diagnostic, filemap);
-    let mut p1 = Parser::new(sess, cfg, box srdr);
+    let mut p1 = Parser::new(sess, cfg, Box::new(srdr));
     panictry!(p1.parse_all_token_trees())
 }
 
@@ -297,7 +297,7 @@ pub fn tts_to_parser<'a>(sess: &'a ParseSess,
                          tts: Vec<ast::TokenTree>,
                          cfg: ast::CrateConfig) -> Parser<'a> {
     let trdr = lexer::new_tt_reader(&sess.span_diagnostic, None, None, tts);
-    let mut p = Parser::new(sess, cfg, box trdr);
+    let mut p = Parser::new(sess, cfg, Box::new(trdr));
     panictry!(p.check_unknown_macro_variable());
     p
 }
@@ -360,7 +360,7 @@ pub mod with_hygiene {
         use super::lexer::make_reader_with_embedded_idents as make_reader;
         let cfg = Vec::new();
         let srdr = make_reader(&sess.span_diagnostic, filemap);
-        let mut p1 = Parser::new(sess, cfg, box srdr);
+        let mut p1 = Parser::new(sess, cfg, Box::new(srdr));
         panictry!(p1.parse_all_token_trees())
     }
 }
@@ -536,7 +536,7 @@ pub fn raw_str_lit(lit: &str) -> String {
 // check if `s` looks like i32 or u1234 etc.
 fn looks_like_width_suffix(first_chars: &[char], s: &str) -> bool {
     s.len() > 1 &&
-        first_chars.contains(&s.char_at(0)) &&
+        first_chars.contains(&char_at(s, 0)) &&
         s[1..].chars().all(|c| '0' <= c && c <= '9')
 }
 
@@ -673,8 +673,8 @@ pub fn integer_lit(s: &str, suffix: Option<&str>, sd: &SpanHandler, sp: Span) ->
     let orig = s;
     let mut ty = ast::UnsuffixedIntLit(ast::Plus);
 
-    if s.char_at(0) == '0' && s.len() > 1 {
-        match s.char_at(1) {
+    if char_at(s, 0) == '0' && s.len() > 1 {
+        match char_at(s, 1) {
             'x' => base = 16,
             'o' => base = 8,
             'b' => base = 2,
@@ -834,28 +834,44 @@ mod test {
     fn string_to_tts_macro () {
         let tts = string_to_tts("macro_rules! zip (($a)=>($a))".to_string());
         let tts: &[ast::TokenTree] = &tts[..];
-        match tts {
-            [ast::TtToken(_, token::Ident(name_macro_rules, token::Plain)),
-             ast::TtToken(_, token::Not),
-             ast::TtToken(_, token::Ident(name_zip, token::Plain)),
-             ast::TtDelimited(_, ref macro_delimed)]
+
+        match (tts.len(), tts.get(0), tts.get(1), tts.get(2), tts.get(3)) {
+            (
+                4,
+                Some(&ast::TtToken(_, token::Ident(name_macro_rules, token::Plain))),
+                Some(&ast::TtToken(_, token::Not)),
+                Some(&ast::TtToken(_, token::Ident(name_zip, token::Plain))),
+                Some(&ast::TtDelimited(_, ref macro_delimed)),
+            )
             if name_macro_rules.as_str() == "macro_rules"
             && name_zip.as_str() == "zip" => {
-                match &macro_delimed.tts[..] {
-                    [ast::TtDelimited(_, ref first_delimed),
-                     ast::TtToken(_, token::FatArrow),
-                     ast::TtDelimited(_, ref second_delimed)]
+                let tts = &macro_delimed.tts[..];
+                match (tts.len(), tts.get(0), tts.get(1), tts.get(2)) {
+                    (
+                        3,
+                        Some(&ast::TtDelimited(_, ref first_delimed)),
+                        Some(&ast::TtToken(_, token::FatArrow)),
+                        Some(&ast::TtDelimited(_, ref second_delimed)),
+                    )
                     if macro_delimed.delim == token::Paren => {
-                        match &first_delimed.tts[..] {
-                            [ast::TtToken(_, token::Dollar),
-                             ast::TtToken(_, token::Ident(name, token::Plain))]
+                        let tts = &first_delimed.tts[..];
+                        match (tts.len(), tts.get(0), tts.get(1)) {
+                            (
+                                2,
+                                Some(&ast::TtToken(_, token::Dollar)),
+                                Some(&ast::TtToken(_, token::Ident(name, token::Plain))),
+                            )
                             if first_delimed.delim == token::Paren
                             && name.as_str() == "a" => {},
                             _ => panic!("value 3: {:?}", **first_delimed),
                         }
-                        match &second_delimed.tts[..] {
-                            [ast::TtToken(_, token::Dollar),
-                             ast::TtToken(_, token::Ident(name, token::Plain))]
+                        let tts = &second_delimed.tts[..];
+                        match (tts.len(), tts.get(0), tts.get(1)) {
+                            (
+                                2,
+                                Some(&ast::TtToken(_, token::Dollar)),
+                                Some(&ast::TtToken(_, token::Ident(name, token::Plain))),
+                            )
                             if second_delimed.delim == token::Paren
                             && name.as_str() == "a" => {},
                             _ => panic!("value 4: {:?}", **second_delimed),
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 0515d1ae945..796bc2a3513 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -78,6 +78,7 @@ use parse::PResult;
 use diagnostic::FatalError;
 
 use std::collections::HashSet;
+use std::fs;
 use std::io::prelude::*;
 use std::mem;
 use std::path::{Path, PathBuf};
@@ -436,10 +437,11 @@ impl<'a> Parser<'a> {
             // leave it in the input
             Ok(())
         } else {
-            let mut expected = edible.iter().map(|x| TokenType::Token(x.clone()))
-                                            .collect::<Vec<_>>();
-            expected.extend(inedible.iter().map(|x| TokenType::Token(x.clone())));
-            expected.push_all(&*self.expected_tokens);
+            let mut expected = edible.iter()
+                .map(|x| TokenType::Token(x.clone()))
+                .chain(inedible.iter().map(|x| TokenType::Token(x.clone())))
+                .chain(self.expected_tokens.iter().cloned())
+                .collect::<Vec<_>>();
             expected.sort_by(|a, b| a.to_string().cmp(&b.to_string()));
             expected.dedup();
             let expect = tokens_to_string(&expected[..]);
@@ -490,8 +492,10 @@ impl<'a> Parser<'a> {
         debug!("commit_expr {:?}", e);
         if let ExprPath(..) = e.node {
             // might be unit-struct construction; check for recoverableinput error.
-            let mut expected = edible.iter().cloned().collect::<Vec<_>>();
-            expected.push_all(inedible);
+            let expected = edible.iter()
+                .cloned()
+                .chain(inedible.iter().cloned())
+                .collect::<Vec<_>>();
             try!(self.check_for_erroneous_unit_struct_expecting(&expected[..]));
         }
         self.expect_one_of(edible, inedible)
@@ -509,8 +513,10 @@ impl<'a> Parser<'a> {
         if self.last_token
                .as_ref()
                .map_or(false, |t| t.is_ident() || t.is_path()) {
-            let mut expected = edible.iter().cloned().collect::<Vec<_>>();
-            expected.push_all(&inedible);
+            let expected = edible.iter()
+                .cloned()
+                .chain(inedible.iter().cloned())
+                .collect::<Vec<_>>();
             try!(self.check_for_erroneous_unit_struct_expecting(&expected));
         }
         self.expect_one_of(edible, inedible)
@@ -897,7 +903,7 @@ impl<'a> Parser<'a> {
         self.last_span = self.span;
         // Stash token for error recovery (sometimes; clone is not necessarily cheap).
         self.last_token = if self.token.is_ident() || self.token.is_path() {
-            Some(box self.token.clone())
+            Some(Box::new(self.token.clone()))
         } else {
             None
         };
@@ -1187,7 +1193,7 @@ impl<'a> Parser<'a> {
                     debug!("parse_trait_methods(): parsing provided method");
                     let (inner_attrs, body) =
                         try!(p.parse_inner_attrs_and_block());
-                    attrs.push_all(&inner_attrs[..]);
+                    attrs.extend(inner_attrs.iter().cloned());
                     Some(body)
                   }
 
@@ -1578,8 +1584,8 @@ impl<'a> Parser<'a> {
             token::Interpolated(token::NtPath(_)) => Some(try!(self.bump_and_get())),
             _ => None,
         };
-        if let Some(token::Interpolated(token::NtPath(box path))) = found {
-            return Ok(path);
+        if let Some(token::Interpolated(token::NtPath(path))) = found {
+            return Ok(*path);
         }
 
         let lo = self.span.lo;
@@ -4770,8 +4776,8 @@ impl<'a> Parser<'a> {
                 let secondary_path_str = format!("{}/mod.rs", mod_name);
                 let default_path = dir_path.join(&default_path_str[..]);
                 let secondary_path = dir_path.join(&secondary_path_str[..]);
-                let default_exists = default_path.exists();
-                let secondary_exists = secondary_path.exists();
+                let default_exists = fs::metadata(&default_path).is_ok();
+                let secondary_exists = fs::metadata(&secondary_path).is_ok();
 
                 if !self.owns_directory {
                     self.span_err(id_sp,
@@ -4834,7 +4840,7 @@ impl<'a> Parser<'a> {
         let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut();
         match included_mod_stack.iter().position(|p| *p == path) {
             Some(i) => {
-                let mut err = String::from_str("circular modules: ");
+                let mut err = String::from("circular modules: ");
                 let len = included_mod_stack.len();
                 for p in &included_mod_stack[i.. len] {
                     err.push_str(&p.to_string_lossy());