Fix clippy (#15489)

# Description
There are some clippy(version 0.1.86) errors on nushell repo. This pr is
trying to fix it.

# User-Facing Changes
Hopefully none.

# Tests + Formatting
NaN

# After Submitting
NaN

crates/nu-cmd-extra/src/extra/bits/mod.rs

@@ -135,7 +135,7 @@ where
                 (min, max) => (rhs, lhs, max, min),
             };
 
-            let pad = iter::repeat(0).take(max_len - min_len);
+            let pad = iter::repeat_n(0, max_len - min_len);
 
             let mut a;
             let mut b;

crates/nu-cmd-extra/src/extra/bits/shift_left.rs

@@ -249,7 +249,7 @@ fn shift_bytes_and_bits_left(data: &[u8], byte_shift: usize, bit_shift: usize) -
             Last | Only => lhs << bit_shift,
             _ => (lhs << bit_shift) | (rhs >> (8 - bit_shift)),
         })
-        .chain(iter::repeat(0).take(byte_shift))
+        .chain(iter::repeat_n(0, byte_shift))
         .collect::<Vec<u8>>()
 }
 

crates/nu-command/src/debug/inspect_table.rs

@@ -118,7 +118,7 @@ fn increase_string_width(text: &mut String, total: usize) {
     let rest = total - width;
 
     if rest > 0 {
-        text.extend(std::iter::repeat(' ').take(rest));
+        text.extend(std::iter::repeat_n(' ', rest));
     }
 }
 

crates/nu-command/src/filesystem/ls.rs

@@ -378,10 +378,7 @@ fn ls_for_one_pattern(
                 .par_bridge()
                 .filter_map(move |x| match x {
                     Ok(path) => {
-                        let metadata = match std::fs::symlink_metadata(&path) {
-                            Ok(metadata) => Some(metadata),
-                            Err(_) => None,
-                        };
+                        let metadata = std::fs::symlink_metadata(&path).ok();
                         let hidden_dir_clone = Arc::clone(&hidden_dirs);
                         let mut hidden_dir_mutex = hidden_dir_clone
                             .lock()

crates/nu-command/src/filters/chunks.rs

@@ -243,7 +243,7 @@ mod test {
         let chunks = chunk_read.map(|e| e.unwrap()).collect::<Vec<_>>();
         assert_eq!(
             chunks,
-            [s[..4].as_bytes(), s[4..8].as_bytes(), s[8..].as_bytes()]
+            [&s.as_bytes()[..4], &s.as_bytes()[4..8], &s.as_bytes()[8..]]
         );
     }
 
@@ -260,7 +260,7 @@ mod test {
         let chunks = chunk_read.map(|e| e.unwrap()).collect::<Vec<_>>();
         assert_eq!(
             chunks,
-            [s[..4].as_bytes(), s[4..8].as_bytes(), s[8..].as_bytes()]
+            [&s.as_bytes()[..4], &s.as_bytes()[4..8], &s.as_bytes()[8..]]
         );
     }
 

crates/nu-command/src/math/utils.rs

@@ -102,7 +102,7 @@ pub fn calculate(
             mf(&new_vals?, span, name)
         }
         PipelineData::Value(val, ..) => mf(&[val], span, name),
-        PipelineData::Empty { .. } => Err(ShellError::PipelineEmpty { dst_span: name }),
+        PipelineData::Empty => Err(ShellError::PipelineEmpty { dst_span: name }),
         val => Err(ShellError::UnsupportedInput {
             msg: "Only ints, floats, lists, records, or ranges are supported".into(),
             input: "value originates from here".into(),

crates/nu-command/src/network/http/client.rs

@@ -723,7 +723,7 @@ fn transform_response_using_content_type(
                         )
                 })?
                 .path_segments()
-                .and_then(|segments| segments.last())
+                .and_then(|mut segments| segments.next_back())
                 .and_then(|name| if name.is_empty() { None } else { Some(name) })
                 .and_then(|name| {
                     PathBuf::from(name)

crates/nu-command/src/path/join.rs

@@ -175,7 +175,7 @@ fn run(call: &Call, args: &Arguments, input: PipelineData) -> Result<PipelineDat
             handle_value(stream.into_value(), args, head),
             metadata,
         )),
-        PipelineData::Empty { .. } => Err(ShellError::PipelineEmpty { dst_span: head }),
+        PipelineData::Empty => Err(ShellError::PipelineEmpty { dst_span: head }),
         _ => Err(ShellError::UnsupportedInput {
             msg: "Input value cannot be joined".to_string(),
             input: "value originates from here".into(),

crates/nu-engine/src/compile/redirect.rs

@@ -98,7 +98,7 @@ pub(crate) fn finish_redirection(
         if !matches!(
             modes.err,
             Some(Spanned {
-                item: RedirectMode::Pipe { .. },
+                item: RedirectMode::Pipe,
                 ..
             })
         ) {

crates/nu-explore/src/views/binary/binary_widget.rs

@@ -323,9 +323,7 @@ fn repeat_vertical(
     c: char,
     style: TextStyle,
 ) {
-    let text = std::iter::repeat(c)
-        .take(width as usize)
-        .collect::<String>();
+    let text = std::iter::repeat_n(c, width as usize).collect::<String>();
     let style = text_style_to_tui_style(style);
     let span = Span::styled(text, style);
 

crates/nu-parser/src/parser.rs

@@ -2678,7 +2678,7 @@ pub fn parse_unit_value<'res>(
 
     if let Some((unit, name, convert)) = unit_groups.iter().find(|x| value.ends_with(x.1)) {
         let lhs_len = value.len() - name.len();
-        let lhs = strip_underscores(value[..lhs_len].as_bytes());
+        let lhs = strip_underscores(&value.as_bytes()[..lhs_len]);
         let lhs_span = Span::new(span.start, span.start + lhs_len);
         let unit_span = Span::new(span.start + lhs_len, span.end);
         if lhs.ends_with('$') {

crates/nu-path/src/dots.rs

@@ -46,7 +46,7 @@ pub fn expand_ndots(path: impl AsRef<Path>) -> PathBuf {
 pub fn expand_dots(path: impl AsRef<Path>) -> PathBuf {
     // Check if the last component of the path is a normal component.
     fn last_component_is_normal(path: &Path) -> bool {
-        matches!(path.components().last(), Some(Component::Normal(_)))
+        matches!(path.components().next_back(), Some(Component::Normal(_)))
     }
 
     let path = path.as_ref();
@@ -61,7 +61,7 @@ pub fn expand_dots(path: impl AsRef<Path>) -> PathBuf {
                 // no-op
             }
             _ => {
-                let prev_component = result.components().last();
+                let prev_component = result.components().next_back();
                 if prev_component == Some(Component::RootDir) && component == Component::ParentDir {
                     continue;
                 }

crates/nu-path/src/tilde.rs

@@ -29,7 +29,7 @@ fn expand_tilde_with_home(path: impl AsRef<Path>, home: Option<PathBuf>) -> Path
         };
     }
 
-    let path_last_char = path.as_os_str().to_string_lossy().chars().last();
+    let path_last_char = path.as_os_str().to_string_lossy().chars().next_back();
     let need_trailing_slash = path_last_char == Some('/') || path_last_char == Some('\\');
 
     match home {
@@ -94,7 +94,7 @@ fn user_home_dir(username: &str) -> PathBuf {
             if !cfg!(target_os = "android")
                 && expected_path
                     .components()
-                    .last()
+                    .next_back()
                     .map(|last| last != Component::Normal(username.as_ref()))
                     .unwrap_or(false)
             {

crates/nu-protocol/src/engine/state_working_set.rs

@@ -884,7 +884,7 @@ impl<'a> StateWorkingSet<'a> {
                 .active_overlay_names(&mut removed_overlays)
                 .iter()
                 .rev()
-                .last()
+                .next_back()
             {
                 return last_name;
             }
@@ -900,7 +900,7 @@ impl<'a> StateWorkingSet<'a> {
             if let Some(last_overlay) = scope_frame
                 .active_overlays(&mut removed_overlays)
                 .rev()
-                .last()
+                .next_back()
             {
                 return last_overlay;
             }

crates/nu-protocol/src/lev_distance.rs

@@ -88,7 +88,7 @@ pub fn lev_distance_with_substrings(a: &str, b: &str, limit: usize) -> Option<us
         1 // Exact substring match, but not a total word match so return non-zero
     } else if !big_len_diff {
         // Not a big difference in length, discount cost of length difference
-        score + (len_diff + 1) / 2
+        score + len_diff.div_ceil(2)
     } else {
         // A big difference in length, add back the difference in length to the score
         score + len_diff

crates/nu-protocol/src/value/from_value.rs

@@ -133,7 +133,7 @@ pub trait FromValue: Sized {
         Type::Custom(
             any::type_name::<Self>()
                 .split(':')
-                .last()
+                .next_back()
                 .expect("str::split returns an iterator with at least one element")
                 .to_string()
                 .into_boxed_str(),

crates/nu-table/src/unstructured_table.rs

@@ -119,7 +119,7 @@ fn build_vertical_map(record: Record, config: &Config) -> TableValue {
 fn string_append_to_width(key: &mut String, max: usize) {
     let width = string_width(key);
     let rest = max - width;
-    key.extend(std::iter::repeat(' ').take(rest));
+    key.extend(std::iter::repeat_n(' ', rest));
 }
 
 fn build_vertical_array(vals: Vec<Value>, config: &Config) -> TableValue {

crates/nu-term-grid/src/grid.rs

@@ -39,15 +39,15 @@
 //! that dictate how the grid is formatted:
 //!
 //! - `filling`: what to put in between two columns — either a number of
-//!    spaces, or a text string;
+//!   spaces, or a text string;
 //! - `direction`, which specifies whether the cells should go along
-//!    rows, or columns:
+//!   rows, or columns:
 //!     - `Direction::LeftToRight` starts them in the top left and
-//!        moves *rightwards*, going to the start of a new row after reaching the
-//!        final column;
+//!       moves *rightwards*, going to the start of a new row after reaching the
+//!       final column;
 //!     - `Direction::TopToBottom` starts them in the top left and moves
-//!        *downwards*, going to the top of a new column after reaching the final
-//!        row.
+//!       *downwards*, going to the top of a new column after reaching the final
+//!       row.
 //!
 //!
 //! ## Displaying a grid
@@ -93,7 +93,7 @@
 
 use std::cmp::max;
 use std::fmt;
-use std::iter::repeat;
+use std::iter::repeat_n;
 use unicode_width::UnicodeWidthStr;
 
 fn unicode_width_strip_ansi(astring: &str) -> usize {
@@ -290,7 +290,7 @@ impl Grid {
     }
 
     fn column_widths(&self, num_lines: usize, num_columns: usize) -> Dimensions {
-        let mut widths: Vec<Width> = repeat(0).take(num_columns).collect();
+        let mut widths: Vec<Width> = repeat_n(0, num_columns).collect();
         for (index, cell) in self.cells.iter().enumerate() {
             let index = match self.options.direction {
                 Direction::LeftToRight => index % num_columns,

crates/nu_plugin_polars/src/dataframe/values/nu_dataframe/mod.rs

@@ -317,7 +317,7 @@ impl NuDataFrame {
         let series = self.as_series(span)?;
         let column = conversion::create_column_from_series(&series, row, row + 1, span)?;
 
-        if column.len() == 0 {
+        if column.is_empty() {
             Err(ShellError::AccessEmptyContent { span })
         } else {
             let value = column