refactor/polish ~ fix cargo clippy complaints (iter_nth_zero)

src/chmod/chmod.rs

@@ -117,7 +117,7 @@ pub fn uumain(mut args: Vec<String>) -> i32 {
 
 fn sanitize_input(args: &mut Vec<String>) -> Option<String> {
     for i in 0..args.len() {
-        let first = args[i].chars().nth(0).unwrap();
+        let first = args[i].chars().next().unwrap();
         if first != '-' {
             continue;
         }

src/cp/cp.rs

@@ -128,7 +128,7 @@ macro_rules! prompt_yes(
         crash_if_err!(1, stdout().flush());
         let mut s = String::new();
         match stdin().read_line(&mut s) {
-            Ok(_) => match s.char_indices().nth(0) {
+            Ok(_) => match s.char_indices().next() {
                 Some((_, x)) => x == 'y' || x == 'Y',
                 _ => false
             },

src/join/join.rs

@@ -569,7 +569,7 @@ FILENUM is 1 or 2, corresponding to FILE1 or FILE2",
     if let Some(value) = matches.value_of("t") {
         settings.separator = match value.len() {
             0 => Sep::Line,
-            1 => Sep::Char(value.chars().nth(0).unwrap()),
+            1 => Sep::Char(value.chars().next().unwrap()),
             _ => crash!(1, "multi-character tab {}", value),
         };
     }

src/ln/ln.rs

@@ -325,7 +325,7 @@ fn link(src: &PathBuf, dst: &PathBuf, settings: &Settings) -> Result<()> {
 fn read_yes() -> bool {
     let mut s = String::new();
     match stdin().read_line(&mut s) {
-        Ok(_) => match s.char_indices().nth(0) {
+        Ok(_) => match s.char_indices().next() {
             Some((_, x)) => x == 'y' || x == 'Y',
             _ => false,
         },

src/mknod/mknod.rs

@@ -130,7 +130,7 @@ for details about the options it supports.",
             // 'mknod /dev/rst0 character 18 0'.
             let ch = args[1]
                 .chars()
-                .nth(0)
+                .next()
                 .expect("Failed to get the first char");
 
             if ch == 'p' {

src/mv/mv.rs

@@ -399,7 +399,7 @@ fn rename(from: &PathBuf, to: &PathBuf, b: &Behaviour) -> Result<()> {
 fn read_yes() -> bool {
     let mut s = String::new();
     match stdin().read_line(&mut s) {
-        Ok(_) => match s.chars().nth(0) {
+        Ok(_) => match s.chars().next() {
             Some(x) => x == 'y' || x == 'Y',
             _ => false,
         },