fix some clippy warnings (#380)

14 files changed, 67 insertions, 86 deletions

diff --git a/src/ansi/mod.rs b/src/ansi/mod.rs
index e2fdaf7f..fc28fc9c 100644
--- a/src/ansi/mod.rs
+++ b/src/ansi/mod.rs
@@ -60,7 +60,7 @@ pub fn truncate_str<'a, 'b>(s: &'a str, display_width: usize, tail: &'b str) ->
         }
     }
 
-    return Cow::from(format!("{}{}", result, result_tail));
+    Cow::from(format!("{}{}", result, result_tail))
 }
 
 pub fn parse_first_style(s: &str) -> Option<ansi_term::Style> {
@@ -72,7 +72,7 @@ pub fn parse_first_style(s: &str) -> Option<ansi_term::Style> {
 
 pub fn string_starts_with_ansi_style_sequence(s: &str) -> bool {
     AnsiElementIterator::new(s)
-        .nth(0)
+        .next()
         .map(|el| matches!(el, Element::CSI(_, _, _)))
         .unwrap_or(false)
 }
diff --git a/src/color.rs b/src/color.rs
index ed0f4f75..a34628d6 100644
--- a/src/color.rs
+++ b/src/color.rs
@@ -17,7 +17,7 @@ pub fn parse_color(s: &str, true_color: bool) -> Option<Color> {
         eprintln!("Invalid color or style attribute: {}", s);
         process::exit(1);
     };
-    let syntect_color = if s.starts_with("#") {
+    let syntect_color = if s.starts_with('#') {
         SyntectColor::from_str(s).unwrap_or_else(|_| die())
     } else {
         s.parse::<u8>()
diff --git a/src/config.rs b/src/config.rs
index b383784a..2d4ee766 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -161,20 +161,17 @@ impl From<cli::Opt> for Config {
             hyperlinks_file_link_format: opt.hyperlinks_file_link_format,
             inspect_raw_lines: opt.computed.inspect_raw_lines,
             keep_plus_minus_markers: opt.keep_plus_minus_markers,
-            line_numbers: match opt.computed.line_numbers_mode {
-                cli::LineNumbersMode::Full => true,
-                _ => false,
-            },
+            line_numbers: matches!(opt.computed.line_numbers_mode, cli::LineNumbersMode::Full),
             line_numbers_left_format: opt.line_numbers_left_format,
             line_numbers_left_style,
             line_numbers_minus_style,
             line_numbers_plus_style,
             line_numbers_right_format: opt.line_numbers_right_format,
             line_numbers_right_style,
-            line_numbers_show_first_line_number: match opt.computed.line_numbers_mode {
-                cli::LineNumbersMode::First => true,
-                _ => false,
-            },
+            line_numbers_show_first_line_number: matches!(
+                opt.computed.line_numbers_mode,
+                cli::LineNumbersMode::First
+            ),
             line_numbers_zero_style,
             max_buffered_lines: 32,
             max_line_distance: opt.max_line_distance,
@@ -182,7 +179,7 @@ impl From<cli::Opt> for Config {
             max_line_length: opt.max_line_length,
             minus_emph_style,
             minus_empty_line_marker_style,
-            minus_file: opt.minus_file.map(|s| s.clone()),
+            minus_file: opt.minus_file,
             minus_non_emph_style,
             minus_style,
             navigate: opt.navigate,
@@ -191,7 +188,7 @@ impl From<cli::Opt> for Config {
             paging_mode: opt.computed.paging_mode,
             plus_emph_style,
             plus_empty_line_marker_style,
-            plus_file: opt.plus_file.map(|s| s.clone()),
+            plus_file: opt.plus_file,
             plus_non_emph_style,
             plus_style,
             git_minus_style,
@@ -211,8 +208,8 @@ impl From<cli::Opt> for Config {
     }
 }
 
-fn make_hunk_styles<'a>(
-    opt: &'a cli::Opt,
+fn make_hunk_styles(
+    opt: &cli::Opt,
 ) -> (
     Style,
     Style,
@@ -350,7 +347,7 @@ fn make_hunk_styles<'a>(
     )
 }
 
-fn make_line_number_styles<'a>(opt: &'a cli::Opt) -> (Style, Style, Style, Style, Style) {
+fn make_line_number_styles(opt: &cli::Opt) -> (Style, Style, Style, Style, Style) {
     let true_color = opt.computed.true_color;
     let line_numbers_left_style =
         Style::from_str(&opt.line_numbers_left_style, None, None, true_color, false);
diff --git a/src/delta.rs b/src/delta.rs
index c0ad1ed3..2607d1c3 100644
--- a/src/delta.rs
+++ b/src/delta.rs
@@ -35,10 +35,7 @@ pub enum Source {
 
 impl State {
     fn is_in_hunk(&self) -> bool {
-        match *self {
-            State::HunkHeader | State::HunkZero | State::HunkMinus(_) | State::HunkPlus(_) => true,
-            _ => false,
-        }
+        matches!(*self, State::HunkHeader | State::HunkZero | State::HunkMinus(_) | State::HunkPlus(_))
     }
 }
 
@@ -267,14 +264,8 @@ fn handle_commit_meta_header_line(
     };
     let (formatted_line, formatted_raw_line) = if config.hyperlinks {
         (
-            Cow::from(
-                features::hyperlinks::format_commit_line_with_osc8_commit_hyperlink(line, config),
-            ),
-            Cow::from(
-                features::hyperlinks::format_commit_line_with_osc8_commit_hyperlink(
-                    raw_line, config,
-                ),
-            ),
+            features::hyperlinks::format_commit_line_with_osc8_commit_hyperlink(line, config),
+            features::hyperlinks::format_commit_line_with_osc8_commit_hyperlink(raw_line, config),
         )
     } else {
         (Cow::from(line), Cow::from(raw_line))
@@ -433,7 +424,7 @@ fn handle_hunk_header_line(
         writeln!(painter.writer)?;
     } else {
         let line = match painter.prepare(&raw_code_fragment, false) {
-            s if s.len() > 0 => format!("{} ", s),
+            s if !s.is_empty() => format!("{} ", s),
             s => s,
         };
         writeln!(painter.writer)?;
diff --git a/src/env.rs b/src/env.rs
index 0a988f9a..9792355b 100644
--- a/src/env.rs
+++ b/src/env.rs
@@ -3,7 +3,7 @@ use std::env;
 /// If `name` is set and, after trimming whitespace, is not empty string, then return that trimmed
 /// string. Else None.
 pub fn get_env_var(name: &str) -> Option<String> {
-    match env::var(name).unwrap_or("".to_string()).trim() {
+    match env::var(name).unwrap_or_else(|_| "".to_string()).trim() {
         "" => None,
         non_empty_string => Some(non_empty_string.to_string()),
     }
diff --git a/src/features/hyperlinks.rs b/src/features/hyperlinks.rs
index 8fc58e9f..3bb5e70c 100644
--- a/src/features/hyperlinks.rs
+++ b/src/features/hyperlinks.rs
@@ -67,9 +67,9 @@ lazy_static! {
     static ref COMMIT_LINE_REGEX: Regex = Regex::new("(.* )([0-9a-f]{40})(.*)").unwrap();
 }
 
-fn format_commit_line_captures_with_osc8_commit_hyperlink<'a, 'b>(
-    captures: &'a Captures,
-    github_repo: &'b str,
+fn format_commit_line_captures_with_osc8_commit_hyperlink(
+    captures: &Captures,
+    github_repo: &str,
 ) -> String {
     let commit = captures.get(2).unwrap().as_str();
     format!(
diff --git a/src/features/line_numbers.rs b/src/features/line_numbers.rs
index e03da5f9..19c35d40 100644
--- a/src/features/line_numbers.rs
+++ b/src/features/line_numbers.rs
@@ -234,7 +234,7 @@ fn parse_line_number_format<'a>(format_string: &'a str) -> LineNumberFormatData<
 }
 
 fn format_and_paint_line_number_field<'a>(
-    format_data: &Vec<LineNumberPlaceholderData<'a>>,
+    format_data: &[LineNumberPlaceholderData<'a>],
     style: &Style,
     minus_number: Option<usize>,
     plus_number: Option<usize>,
diff --git a/src/features/side_by_side.rs b/src/features/side_by_side.rs
index e3837455..04380461 100644
--- a/src/features/side_by_side.rs
+++ b/src/features/side_by_side.rs
@@ -177,8 +177,8 @@ pub fn paint_zero_lines_side_by_side(
 
 fn paint_left_panel_minus_line<'a>(
     line_index: Option<usize>,
-    syntax_style_sections: &Vec<Vec<(SyntectStyle, &str)>>,
-    diff_style_sections: &Vec<Vec<(Style, &str)>>,
+    syntax_style_sections: &[Vec<(SyntectStyle, &str)>],
+    diff_style_sections: &[Vec<(Style, &str)>],
     state: &'a State,
     line_numbers_data: &mut Option<&mut line_numbers::LineNumbersData>,
     prefix: &str,
@@ -210,8 +210,8 @@ fn paint_left_panel_minus_line<'a>(
 
 fn paint_right_panel_plus_line<'a>(
     line_index: Option<usize>,
-    syntax_style_sections: &Vec<Vec<(SyntectStyle, &str)>>,
-    diff_style_sections: &Vec<Vec<(Style, &str)>>,
+    syntax_style_sections: &[Vec<(SyntectStyle, &str)>],
+    diff_style_sections: &[Vec<(Style, &str)>],
     state: &'a State,
     line_numbers_data: &mut Option<&mut line_numbers::LineNumbersData>,
     prefix: &str,
@@ -243,7 +243,7 @@ fn paint_right_panel_plus_line<'a>(
 fn get_right_fill_style_for_left_panel(
     line_is_empty: bool,
     line_index: Option<usize>,
-    diff_style_sections: &Vec<Vec<(Style, &str)>>,
+    diff_style_sections: &[Vec<(Style, &str)>],
     state: &State,
     background_color_extends_to_terminal_width: Option<bool>,
     config: &Config,
@@ -289,10 +289,10 @@ fn get_right_fill_style_for_left_panel(
 // what this will do is set the line number pair in that function to `(Some(minus_number), None)`,
 // and then only emit the right field (which has a None number, i.e. blank). However, it will also
 // increment the minus line number, so we need to knock that back down.
-fn paint_minus_or_plus_panel_line<'a>(
+fn paint_minus_or_plus_panel_line(
     line_index: Option<usize>,
-    syntax_style_sections: &Vec<Vec<(SyntectStyle, &str)>>,
-    diff_style_sections: &Vec<Vec<(Style, &str)>>,
+    syntax_style_sections: &[Vec<(SyntectStyle, &str)>],
+    diff_style_sections: &[Vec<(Style, &str)>],
     state: &State,
     line_numbers_data: &mut Option<&mut line_numbers::LineNumbersData>,
     panel_side: PanelSide,
@@ -355,7 +355,7 @@ fn right_pad_left_panel_line(
     panel_line: &mut String,
     panel_line_is_empty: bool,
     line_index: Option<usize>,
-    diff_style_sections: &Vec<Vec<(Style, &str)>>,
+    diff_style_sections: &[Vec<(Style, &str)>],
     state: &State,
     background_color_extends_to_terminal_width: Option<bool>,
     config: &Config,
@@ -408,7 +408,7 @@ fn right_fill_right_panel_line(
     panel_line: &mut String,
     panel_line_is_empty: bool,
     line_index: Option<usize>,
-    diff_style_sections: &Vec<Vec<(Style, &str)>>,
+    diff_style_sections: &[Vec<(Style, &str)>],
     state: &State,
     background_color_extends_to_terminal_width: Option<bool>,
     config: &Config,
diff --git a/src/main.rs b/src/main.rs
index a691c331..bd65956d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -29,8 +29,6 @@ use std::io::{self, ErrorKind, Read, Write};
 use std::path::PathBuf;
 use std::process;
 
-use ansi_term;
-use atty;
 use bytelines::ByteLinesReader;
 use itertools::Itertools;
 use structopt::StructOpt;
@@ -237,8 +235,8 @@ fn show_config(config: &config::Config) {
         syntax_theme = config
             .syntax_theme
             .clone()
-            .map(|t| t.name.unwrap_or("none".to_string()))
-            .unwrap_or("none".to_string()),
+            .map(|t| t.name.unwrap_or_else(|| "none".to_string()))
+            .unwrap_or_else(|| "none".to_string()),
         width = match config.decorations_width {
             cli::Width::Fixed(width) => width.to_string(),
             cli::Width::Variable => "variable".to_string(),
@@ -255,8 +253,8 @@ where
     S: AsRef<str>,
 {
     let s = s.as_ref();
-    if s.ends_with(" ")
-        || s.starts_with(" ")
+    if s.ends_with(' ')
+        || s.starts_with(' ')
         || s.contains(&['\\', '{', '}', ':'][..])
         || s.is_empty()
     {
@@ -345,9 +343,9 @@ index f38589a..0f1bb83 100644
 
 pub fn list_syntax_themes() -> std::io::Result<()> {
     if atty::is(atty::Stream::Stdout) {
-        return _list_syntax_themes_for_humans();
+        _list_syntax_themes_for_humans()
     } else {
-        return _list_syntax_themes_for_machines();
+        _list_syntax_themes_for_machines()
     }
 }
 
diff --git a/src/options/rewrite.rs b/src/options/rewrite.rs
index c1f349d7..12597756 100644
--- a/src/options/rewrite.rs
+++ b/src/options/rewrite.rs
@@ -49,7 +49,7 @@ fn rewrite_style_strings_to_honor_deprecated_minus_plus_options(opt: &mut cli::O
         ),
         "minus",
     ) {
-        opt.minus_style = rewritten.to_string();
+        opt.minus_style = rewritten;
     }
     if let Some(rewritten) = _get_rewritten_minus_plus_style_string(
         &opt.minus_emph_style,
@@ -60,7 +60,7 @@ fn rewrite_style_strings_to_honor_deprecated_minus_plus_options(opt: &mut cli::O
         ),
         "minus-emph",
     ) {
-        opt.minus_emph_style = rewritten.to_string();
+        opt.minus_emph_style = rewritten;
     }
     if let Some(rewritten) = _get_rewritten_minus_plus_style_string(
         &opt.plus_style,
@@ -68,7 +68,7 @@ fn rewrite_style_strings_to_honor_deprecated_minus_plus_options(opt: &mut cli::O
         (None, opt.deprecated_plus_background_color.as_deref()),
         "plus",
     ) {
-        opt.plus_style = rewritten.to_string();
+        opt.plus_style = rewritten;
     }
     if let Some(rewritten) = _get_rewritten_minus_plus_style_string(
         &opt.plus_emph_style,
@@ -76,7 +76,7 @@ fn rewrite_style_strings_to_honor_deprecated_minus_plus_options(opt: &mut cli::O
         (None, opt.deprecated_plus_emph_background_color.as_deref()),
         "plus-emph",
     ) {
-        opt.plus_emph_style = rewritten.to_string();
+        opt.plus_emph_style = rewritten;
     }
 }
 
diff --git a/src/options/set.rs b/src/options/set.rs
index a9ca6be7..3683c657 100644
--- a/src/options/set.rs
+++ b/src/options/set.rs
@@ -311,7 +311,7 @@ fn set__light__dark__syntax_theme__options(
 ///
 /// [delta "d"]
 ///     features = f e
-fn gather_features<'a>(
+fn gather_features(
     opt: &cli::Opt,
     builtin_features: &HashMap<String, features::BuiltinFeature>,
     git_config: &Option<git_config::GitConfig>,
@@ -364,7 +364,7 @@ fn gather_features<'a>(
     if let Some(git_config) = git_config {
         // Gather features from [delta] section if --features was not passed.
         if opt.features.is_empty() {
-            if let Some(feature_string) = git_config.get::<String>(&format!("delta.features")) {
+            if let Some(feature_string) = git_config.get::<String>("delta.features") {
                 for feature in split_feature_string(&feature_string.to_lowercase()) {
                     gather_features_recursively(
                         feature,
@@ -390,7 +390,7 @@ fn gather_features<'a>(
 }
 
 /// Add to feature list `features` all features in the tree rooted at `feature`.
-fn gather_features_recursively<'a>(
+fn gather_features_recursively(
     feature: &str,
     features: &mut VecDeque<String>,
     builtin_features: &HashMap<String, features::BuiltinFeature>,
@@ -426,7 +426,7 @@ fn gather_features_recursively<'a>(
 
 /// Look for builtin features requested via boolean feature flags (as opposed to via a "features"
 /// list) in a custom feature section in git config and add them to the features list.
-fn gather_builtin_features_from_flags_in_gitconfig<'a>(
+fn gather_builtin_features_from_flags_in_gitconfig(
     git_config_key: &str,
     features: &mut VecDeque<String>,
     builtin_features: &HashMap<String, features::BuiltinFeature>,
@@ -450,7 +450,7 @@ fn gather_builtin_features_from_flags_in_gitconfig<'a>(
 /// children of a node in the tree are features in (a) and (b). (In both cases the features
 /// referenced will be other builtin features, since a builtin feature is determined at compile
 /// time and therefore cannot know of the existence of a non-builtin custom features in gitconfig).
-fn gather_builtin_features_recursively<'a>(
+fn gather_builtin_features_recursively(
     feature: &str,
     features: &mut VecDeque<String>,
     builtin_features: &HashMap<String, features::BuiltinFeature>,
diff --git a/src/paint.rs b/src/paint.rs
index e69ebeee..c35ba5a5 100644
--- a/src/paint.rs
+++ b/src/paint.rs
@@ -2,7 +2,6 @@ use lazy_static::lazy_static;
 use regex::Regex;
 use std::io::Write;
 
-use ansi_term;
 use itertools::Itertools;
 use syntect::easy::HighlightLines;
 use syntect::highlighting::Style as SyntectStyle;
@@ -65,11 +64,9 @@ impl<'a> Painter<'a> {
                 return syntax;
             }
         }
-        return syntax_set
+        syntax_set
             .find_syntax_by_extension("txt")
-            .unwrap_or_else(|| {
-                delta_unreachable("Failed to find any language syntax definitions.")
-            });
+            .unwrap_or_else(|| delta_unreachable("Failed to find any language syntax definitions."))
     }
 
     pub fn set_highlighter(&mut self) {
@@ -302,7 +299,7 @@ impl<'a> Painter<'a> {
     /// Determine whether the terminal should fill the line rightwards with a background color, and
     /// the style for doing so.
     pub fn get_should_right_fill_background_color_and_fill_style(
-        diff_sections: &Vec<(Style, &str)>,
+        diff_sections: &[(Style, &str)],
         state: &State,
         background_color_extends_to_terminal_width: Option<bool>,
         config: &config::Config,
@@ -379,8 +376,8 @@ impl<'a> Painter<'a> {
 
     /// Return painted line (maybe prefixed with line numbers field) and an is_empty? boolean.
     pub fn paint_line(
-        syntax_sections: &Vec<(SyntectStyle, &str)>,
-        diff_sections: &Vec<(Style, &str)>,
+        syntax_sections: &[(SyntectStyle, &str)],
+        diff_sections: &[(Style, &str)],
         state: &State,
         line_numbers_data: &mut Option<&mut line_numbers::LineNumbersData>,
         side_by_side_panel: Option<side_by_side::PanelSide>,
@@ -424,7 +421,7 @@ impl<'a> Painter<'a> {
                 if prefix != "" {
                     ansi_strings.push(section_style.paint(prefix));
                 }
-                if text.len() > 0 {
+                if !text.is_empty() {
                     text.remove(0);
                 }
                 handled_prefix = true;
@@ -468,7 +465,7 @@ impl<'a> Painter<'a> {
     }
 
     pub fn get_syntax_style_sections_for_lines<'s>(
-        lines: &'s Vec<(String, State)>,
+        lines: &'s [(String, State)],
         state: &State,
         highlighter: &mut HighlightLines,
         config: &config::Config,
@@ -491,8 +488,8 @@ impl<'a> Painter<'a> {
 
     /// Set background styles to represent diff for minus and plus lines in buffer.
     fn get_diff_style_sections<'b>(
-        minus_lines: &'b Vec<(String, State)>,
-        plus_lines: &'b Vec<(String, State)>,
+        minus_lines: &'b [(String, State)],
+        plus_lines: &'b [(String, State)],
         config: &config::Config,
     ) -> (
         Vec<Vec<(Style, &'b str)>>,
@@ -578,7 +575,7 @@ impl<'a> Painter<'a> {
 
 // edits::annotate doesn't return "coalesced" annotations (see comment there), so we can't assume
 // that `sections.len() > 1 <=> (multiple styles)`.
-fn style_sections_contain_more_than_one_style(sections: &Vec<(Style, &str)>) -> bool {
+fn style_sections_contain_more_than_one_style(sections: &[(Style, &str)]) -> bool {
     if sections.len() > 1 {
         let (first_style, _) = sections[0];
         sections
@@ -599,7 +596,7 @@ lazy_static! {
 // TODO: Git recognizes blank lines at end of file (blank-at-eof) as a whitespace error but delta
 // does not yet.
 // https://git-scm.com/docs/git-config#Documentation/git-config.txt-corewhitespace
-fn is_whitespace_error(sections: &Vec<(Style, &str)>) -> bool {
+fn is_whitespace_error(sections: &[(Style, &str)]) -> bool {
     !sections
         .iter()
         .any(|(_, s)| NON_WHITESPACE_REGEX.is_match(s))
@@ -692,7 +689,7 @@ mod superimpose_style_sections {
             }
 
             // TODO: This is not the ideal location for the following code.
-            if current_string.ends_with("\n") {
+            if current_string.ends_with('\n') {
                 // Remove the terminating newline whose presence was necessary for the syntax
                 // highlighter to work correctly.
                 current_string.truncate(current_string.len() - 1);
diff --git a/src/parse.rs b/src/parse.rs
index cc259e37..6188117d 100644
--- a/src/parse.rs
+++ b/src/parse.rs
@@ -63,7 +63,7 @@ pub fn get_file_change_description_from_file_paths(
         format!("comparing: {} ⟶   {}", minus_file, plus_file)
     } else {
         let format_label = |label: &str| {
-            if label.len() > 0 {
+            if !label.is_empty() {
                 format!("{} ", label)
             } else {
                 "".to_string()
@@ -143,7 +143,7 @@ pub fn parse_hunk_header(line: &str) -> (String, Vec<(usize, usize)>) {
         })
         .collect();
     let code_fragment = &caps[2];
-    return (code_fragment.to_string(), line_numbers_and_hunk_lengths);
+    (code_fragment.to_string(), line_numbers_and_hunk_lengths)
 }
 
 /// Attempt to parse input as a file path and return extension as a &str.
diff --git a/src/style.rs b/src/style.rs
index 7bf56c71..d25fc2f7 100644
--- a/src/style.rs
+++ b/src/style.rs
@@ -1,7 +1,6 @@
 use std::borrow::Cow;
 use std::fmt;
 
-use ansi_term;
 use lazy_static::lazy_static;
 
 use crate::ansi;
@@ -135,9 +134,8 @@ impl Style {
             }
             (false, None) => words.push("normal".to_string()),
         }
-        match self.ansi_term_style.background {
-            Some(color) => words.push(color::color_to_string(color)),
-            None => {}
+        if let Some(color) = self.ansi_term_style.background {
+            words.push(color::color_to_string(color))
         }
         words.join(" ")
     }
@@ -155,10 +153,10 @@ pub fn ansi_term_style_equality(a: ansi_term::Style, b: ansi_term::Style) -> boo
         ..b
     };
     if a_attrs != b_attrs {
-        return false;
+        false
     } else {
-        return ansi_term_color_equality(a.foreground, b.foreground)
-            & ansi_term_color_equality(a.background, b.background);
+        ansi_term_color_equality(a.foreground, b.foreground)
+            & ansi_term_color_equality(a.background, b.background)
     }
 }
 
@@ -211,7 +209,7 @@ pub fn line_has_style_other_than<'a>(line: &str, styles: impl Iterator<Item = &'
             return false;
         }
     }
-    return true;
+    true
 }
 
 #[cfg(test)]