Remove usage of many unstable features

This removes usage of:

* PathExt
* split_last
* split_last_mut
* catch_panic

The catch_panic one was a little tricky as the ident interner needed to be
cloned across threads (a little unsafely), but it should otherwise be good to
go.

src/bin/rustfmt.rs

@@ -7,8 +7,7 @@
 // <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.
-#![feature(path_ext)]
-#![feature(rustc_private)]
+
 #![cfg(not(test))]
 
 #[macro_use]
@@ -21,7 +20,7 @@ use rustfmt::{WriteMode, run};
 use rustfmt::config::Config;
 
 use std::env;
-use std::fs::{File, PathExt};
+use std::fs::{self, File};
 use std::io::{self, Read};
 use std::path::PathBuf;
 use std::str::FromStr;
@@ -31,7 +30,7 @@ fn lookup_project_file() -> io::Result<PathBuf> {
     let mut current = try!(env::current_dir());
     loop {
         let config_file = current.join("rustfmt.toml");
-        if config_file.exists() {
+        if fs::metadata(&config_file).is_ok() {
             return Ok(config_file);
         } else {
             current = match current.parent() {

src/chains.rs

@@ -72,11 +72,9 @@ pub fn rewrite_chain(mut expr: &ast::Expr,
                                             .collect::<Option<Vec<_>>>());
 
     // Total of all items excluding the last.
-    let almost_total = rewrites.split_last()
-                               .unwrap()
-                               .1
-                               .iter()
-                               .fold(0, |a, b| a + first_line_width(b)) +
+    let almost_total = rewrites[..rewrites.len() - 1]
+                           .iter()
+                           .fold(0, |a, b| a + first_line_width(b)) +
                        parent_rewrite.len();
     let total_width = almost_total + first_line_width(rewrites.last().unwrap());
     let veto_single_line = if context.config.take_source_hints && subexpr_list.len() > 1 {
@@ -95,7 +93,9 @@ pub fn rewrite_chain(mut expr: &ast::Expr,
                            match subexpr_list[0].node {
         ast::Expr_::ExprMethodCall(ref method_name, ref types, ref expressions)
             if context.config.chains_overflow_last => {
-            let (last, init) = rewrites.split_last_mut().unwrap();
+            let len = rewrites.len();
+            let (init, last) = rewrites.split_at_mut(len - 1);
+            let last = &mut last[0];
 
             if init.iter().all(|s| !s.contains('\n')) && total_width <= width {
                 let last_rewrite = width.checked_sub(almost_total)

src/comment.rs

@@ -437,7 +437,7 @@ mod test {
     }
 
     #[test]
-    #[rustfmt_skip]
+    #[cfg_attr(rustfmt, rustfmt_skip)]
     fn format_comments() {
         let config = Default::default();
         assert_eq!("/* test */", rewrite_comment(" //test", true, 100, Indent::new(0, 100),

src/lib.rs

@@ -8,13 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(rustc_private)]
-#![feature(custom_attribute)]
-#![feature(slice_splits)]
-#![feature(slice_patterns)]
-#![feature(catch_panic)]
-#![allow(unused_attributes)]
-
 // TODO we're going to allocate a whole bunch of temp Strings, is it worth
 // keeping some scratch mem for this and running our own StrPool?
 // TODO for lint violations of names, emit a refactor script

src/macros.rs

@@ -20,11 +20,14 @@
 // and those with brackets will be formatted as array literals.
 
 use std::thread;
+use std::collections::hash_map::{HashMap, Entry};
 
 use syntax::ast;
 use syntax::parse::token::{Eof, Comma, Token};
 use syntax::parse::{ParseSess, tts_to_parser};
 use syntax::codemap::{mk_sp, BytePos};
+use syntax::parse::token;
+use syntax::util::interner::StrInterner;
 
 use Indent;
 use rewrite::RewriteContext;
@@ -82,13 +85,16 @@ pub fn rewrite_macro(mac: &ast::Mac,
     }
 
     let wrapped_tt_vec = ForceSend(mac.node.tts.clone());
+    let my_interner = ForceSend(clone_interner());
+
     // Wrap expression parsing logic in a thread since the libsyntax parser
     // panics on failure, which we do not want to propagate.
     // The expression vector is wrapped in an Option inside a Result.
-    let expr_vec_result = thread::catch_panic(move || {
+    let expr_vec_result = thread::spawn(move || {
         let parse_session = ParseSess::new();
         let mut parser = tts_to_parser(&parse_session, wrapped_tt_vec.0, vec![]);
         let mut expr_vec = vec![];
+        token::get_ident_interner().reset(my_interner.0);
 
         loop {
             expr_vec.push(parser.parse_expr());
@@ -106,9 +112,10 @@ pub fn rewrite_macro(mac: &ast::Mac,
             }
         }
 
-        Some(expr_vec)
+        Some(ForceSend((expr_vec, clone_interner())))
     });
-    let expr_vec = try_opt!(try_opt!(expr_vec_result.ok()));
+    let (expr_vec, interner) = try_opt!(try_opt!(expr_vec_result.join().ok())).0;
+    token::get_ident_interner().reset(interner);
 
     match style {
         MacroStyle::Parens => {
@@ -139,6 +146,23 @@ pub fn rewrite_macro(mac: &ast::Mac,
     }
 }
 
+fn clone_interner() -> StrInterner {
+    let old = token::get_ident_interner();
+    let new = StrInterner::new();
+    let mut map = HashMap::new();
+    for name in (0..old.len()).map(|i| i as u32).map(ast::Name) {
+        match map.entry(old.get(name)) {
+            Entry::Occupied(e) => {
+                new.gensym_copy(*e.get());
+            }
+            Entry::Vacant(e) => {
+                e.insert(new.intern(&old.get(name)));
+            }
+        }
+    }
+    return new
+}
+
 fn macro_style(mac: &ast::Mac, context: &RewriteContext) -> MacroStyle {
     let snippet = context.snippet(mac.span);
     let paren_pos = snippet.find_uncommented("(").unwrap_or(usize::max_value());