remove box_syntax feature from fmt, base64, cat

src/base64/base64.rs

@@ -1,5 +1,5 @@
 #![crate_name = "base64"]
-#![feature(box_syntax, rustc_private)]
+#![feature(rustc_private)]
 
 /*
  * This file is part of the uutils coreutils package.
@@ -80,11 +80,11 @@ pub fn uumain(args: Vec<String>) -> i32 {
     let mut file_buf;
     let mut input = if matches.free.is_empty() || &matches.free[0][..] == "-" {
         stdin_buf = stdin();
-        BufReader::new(box stdin_buf as Box<Read+'static>)
+        BufReader::new(Box::new(stdin_buf) as Box<Read+'static>)
     } else {
         let path = Path::new(&matches.free[0][..]);
         file_buf = safe_unwrap!(File::open(&path));
-        BufReader::new(box file_buf as Box<Read+'static>)
+        BufReader::new(Box::new(file_buf) as Box<Read+'static>)
     };
 
     match mode {

src/cat/cat.rs

@@ -1,5 +1,5 @@
 #![crate_name = "cat"]
-#![feature(rustc_private, box_syntax, unsafe_destructor)]
+#![feature(rustc_private, unsafe_destructor)]
 
 /*
  * This file is part of the uutils coreutils package.
@@ -261,11 +261,11 @@ fn open(path: &str) -> Option<(Box<Read>, bool)> {
     if path == "-" {
         let stdin = stdin();
         let interactive = unsafe { isatty(STDIN_FILENO) } != 0 as c_int;
-        return Some((box stdin as Box<Read>, interactive));
+        return Some((Box::new(stdin) as Box<Read>, interactive));
     }
 
     match File::open(path) {
-        Ok(f) => Some((box f as Box<Read>, false)),
+        Ok(f) => Some((Box::new(f) as Box<Read>, false)),
         Err(e) => {
             (writeln!(&mut stderr(), "cat: {0}: {1}", path, e.to_string())).unwrap();
             None

src/fmt/fmt.rs

@@ -1,5 +1,5 @@
 #![crate_name = "fmt"]
-#![feature(box_syntax,rustc_private,str_char,unicode,core)]
+#![feature(rustc_private,str_char,unicode,core)]
 
 /*
  * This file is part of `fmt` from the uutils coreutils package.
@@ -197,9 +197,9 @@ pub fn uumain(args: Vec<String>) -> i32 {
 
     for i in files.iter().map(|x| &x[..]) {
         let mut fp = match i {
-            "-" => BufReader::new(box stdin() as Box<Read+'static>),
+            "-" => BufReader::new(Box::new(stdin()) as Box<Read+'static>),
             _ => match File::open(i) {
-                Ok(f) => BufReader::new(box f as Box<Read+'static>),
+                Ok(f) => BufReader::new(Box::new(f) as Box<Read+'static>),
                 Err(e) => {
                     show_warning!("{}: {}", i, e);
                     continue;