Fix clippy warnings (#1298)

* Fix clippy warnings

- `clippy::uninlined_format_args`

* Fix clippy warnings

- `clippy::clone_on_copy`
- `clippy::explicit_auto_deref`
- `clippy::iter_cloned_collect`
- `clippy::map_clone`
- `clippy::needless_borrow`
- `clippy::needless_lifetimes`
- `clippy::needless_return`
- `clippy::redundant_clone`
- `clippy::redundant_field_names`
- `clippy::seek_to_start_instead_of_rewind`
- `clippy::unnecessary_cast`
- `clippy::unused_unit`

42 files changed, 151 insertions, 188 deletions

diff --git a/src/align.rs b/src/align.rs
index b2e2bdfe..90491ce2 100644
--- a/src/align.rs
+++ b/src/align.rs
@@ -408,7 +408,7 @@ mod tests {
     }
 
     impl<'a> TestCase<'a> {
-        pub fn run(&self) -> () {
+        pub fn run(&self) {
             self.assert_string_distance_parts();
             assert_eq!(operations(self.before, self.after), self.operations);
         }
diff --git a/src/ansi/mod.rs b/src/ansi/mod.rs
index 2b7b2f60..64b51c8b 100644
--- a/src/ansi/mod.rs
+++ b/src/ansi/mod.rs
@@ -36,7 +36,7 @@ pub fn measure_text_width(s: &str) -> usize {
 //
 // 3. If tail was exhausted, then contribute graphemes and ANSI escape sequences from `s` until the
 //    display_width of the result would exceed `display_width`.
-pub fn truncate_str<'a, 'b>(s: &'a str, display_width: usize, tail: &'b str) -> Cow<'a, str> {
+pub fn truncate_str<'a>(s: &'a str, display_width: usize, tail: &str) -> Cow<'a, str> {
     let items = ansi_strings_iterator(s).collect::<Vec<(&str, bool)>>();
     let width = strip_ansi_codes_from_strings_iterator(items.iter().copied()).width();
     if width <= display_width {
@@ -68,7 +68,7 @@ pub fn truncate_str<'a, 'b>(s: &'a str, display_width: usize, tail: &'b str) ->
         }
     }
 
-    Cow::from(format!("{}{}", result, result_tail))
+    Cow::from(format!("{result}{result_tail}"))
 }
 
 pub fn parse_style_sections(s: &str) -> Vec<(ansi_term::Style, &str)> {
@@ -176,7 +176,7 @@ pub fn explain_ansi(line: &str, colorful: bool) -> String {
             if colorful {
                 format!("({}){}", style.to_painted_string(), style.paint(s))
             } else {
-                format!("({}){}", style, s)
+                format!("({style}){s}")
             }
         })
         .collect()
diff --git a/src/color.rs b/src/color.rs
index 52904b65..a4b96b58 100644
--- a/src/color.rs
+++ b/src/color.rs
@@ -14,7 +14,7 @@ pub fn parse_color(s: &str, true_color: bool, git_config: Option<&GitConfig>) ->
         return None;
     }
     let die = || {
-        fatal(format!("Invalid color or style attribute: {}", s));
+        fatal(format!("Invalid color or style attribute: {s}"));
     };
     let syntect_color = if s.starts_with('#') {
         SyntectColor::from_str(s).unwrap_or_else(|_| die())
@@ -27,7 +27,7 @@ pub fn parse_color(s: &str, true_color: bool, git_config: Option<&GitConfig>) ->
             .or_else(|| utils::syntect::syntect_color_from_name(s));
         if syntect_color.is_none() {
             if let Some(git_config) = git_config {
-                if let Some(val) = git_config.get::<String>(&format!("delta.{}", s)) {
+                if let Some(val) = git_config.get::<String>(&format!("delta.{s}")) {
                     return parse_color(&val, true_color, None);
                 }
             }
@@ -41,8 +41,8 @@ pub fn parse_color(s: &str, true_color: bool, git_config: Option<&GitConfig>) ->
 pub fn color_to_string(color: Color) -> String {
     match color {
         Color::Fixed(n) if n < 16 => ansi_16_color_number_to_name(n).unwrap().to_string(),
-        Color::Fixed(n) => format!("{}", n),
-        Color::RGB(r, g, b) => format!("\"#{:02x?}{:02x?}{:02x?}\"", r, g, b),
+        Color::Fixed(n) => format!("{n}"),
+        Color::RGB(r, g, b) => format!("\"#{r:02x?}{g:02x?}{b:02x?}\""),
         Color::Black => "black".to_string(),
         Color::Red => "red".to_string(),
         Color::Green => "green".to_string(),
diff --git a/src/config.rs b/src/config.rs
index 24e26a47..3856f669 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -390,9 +390,8 @@ pub fn user_supplied_option(option: &str, arg_matches: &clap::ArgMatches) -> boo
 
 pub fn delta_unreachable(message: &str) -> ! {
     fatal(format!(
-        "{} This should not be possible. \
+        "{message} This should not be possible. \
          Please report the bug at https://github.com/dandavison/delta/issues.",
-        message
     ));
 }
 
diff --git a/src/edits.rs b/src/edits.rs
index bcbead11..eb6a310a 100644
--- a/src/edits.rs
+++ b/src/edits.rs
@@ -470,7 +470,7 @@ mod tests {
     }
 
     fn assert_tokenize(text: &str, expected_tokens: &[&str]) {
-        let actual_tokens = tokenize(text, &*DEFAULT_TOKENIZATION_REGEXP);
+        let actual_tokens = tokenize(text, &DEFAULT_TOKENIZATION_REGEXP);
         assert_eq!(text, expected_tokens.iter().join(""));
         // tokenize() guarantees that the first element of the token stream is "".
         // See comment in Alignment::new()
@@ -861,7 +861,7 @@ mod tests {
             Deletion,
             noop_insertions,
             Insertion,
-            &*DEFAULT_TOKENIZATION_REGEXP,
+            &DEFAULT_TOKENIZATION_REGEXP,
             max_line_distance,
             0.0,
         );
diff --git a/src/features/hyperlinks.rs b/src/features/hyperlinks.rs
index b45de0f8..78be83e9 100644
--- a/src/features/hyperlinks.rs
+++ b/src/features/hyperlinks.rs
@@ -31,7 +31,7 @@ pub fn format_commit_line_with_osc8_commit_hyperlink<'a>(
             let suffix = captures.get(3).map(|m| m.as_str()).unwrap_or("");
             let formatted_commit =
                 format_osc8_hyperlink(&commit_link_format.replace("{commit}", commit), commit);
-            format!("{}{}{}", prefix, formatted_commit, suffix)
+            format!("{prefix}{formatted_commit}{suffix}")
         })
     } else if let Some(GitConfigEntry::GitRemote(repo)) =
         config.git_config.as_ref().and_then(get_remote_url)
@@ -74,7 +74,7 @@ where
         .hyperlinks_file_link_format
         .replace("{path}", &absolute_path.as_ref().to_string_lossy());
     if let Some(n) = line_number {
-        url = url.replace("{line}", &format!("{}", n))
+        url = url.replace("{line}", &format!("{n}"))
     } else {
         url = url.replace("{line}", "")
     };
@@ -138,8 +138,7 @@ pub mod tests {
         ] {
             run_test(FilePathsTestCase {
                 name: &format!(
-                    "delta relative_paths={} calling_cmd={:?}",
-                    delta_relative_paths_option, calling_cmd
+                    "delta relative_paths={delta_relative_paths_option} calling_cmd={calling_cmd:?}",
                 ),
                 true_location_of_file_relative_to_repo_root:
                     true_location_of_file_relative_to_repo_root.as_path(),
@@ -452,7 +451,7 @@ __path__:  some matching line
 
     fn run_test(test_case: FilePathsTestCase) {
         let mut config = integration_test_utils::make_config_from_args(
-            &test_case
+            test_case
                 .get_args()
                 .iter()
                 .map(|s| s.as_str())
@@ -483,12 +482,11 @@ __path__:  some matching line
                     test_case.path_in_delta_input,
                     test_case.path_in_grep_output()
                 );
-                delta_test.with_input(
-                    &GIT_GREP_OUTPUT.replace("__path__", &test_case.path_in_delta_input),
-                )
+                delta_test
+                    .with_input(&GIT_GREP_OUTPUT.replace("__path__", test_case.path_in_delta_input))
             }
             CallingProcess::OtherGrep => delta_test
-                .with_input(&GIT_GREP_OUTPUT.replace("__path__", &test_case.path_in_delta_input)),
+                .with_input(&GIT_GREP_OUTPUT.replace("__path__", test_case.path_in_delta_input)),
         };
         let make_expected_hyperlink = |text| {
             format_osc8_hyperlink(
diff --git a/src/features/line_numbers.rs b/src/features/line_numbers.rs
index bbdeb592..99a97775 100644
--- a/src/features/line_numbers.rs
+++ b/src/features/line_numbers.rs
@@ -198,7 +198,7 @@ impl<'a> LineNumbersData<'a> {
             format_data: if insert_center_space_on_odd_width {
                 let format_left = vec![format::FormatStringPlaceholderData::default()];
                 let format_right = vec![format::FormatStringPlaceholderData {
-                    prefix: format!("{}", ODD_PAD_CHAR).into(),
+                    prefix: format!("{ODD_PAD_CHAR}").into(),
                     prefix_len: 1,
                     ..Default::default()
                 }];
@@ -327,9 +327,9 @@ pub mod tests {
 
     use super::*;
 
-    pub fn parse_line_number_format_with_default_regex<'a>(
-        format_string: &'a str,
-    ) -> FormatStringData<'a> {
+    pub fn parse_line_number_format_with_default_regex(
+        format_string: &str,
+    ) -> FormatStringData<'_> {
         format::parse_line_number_format(format_string, &LINE_NUMBERS_PLACEHOLDER_REGEX, false)
     }
 
@@ -460,7 +460,7 @@ pub mod tests {
         assert_eq!(
             format::parse_line_number_format("|{nm:<4}|", &LINE_NUMBERS_PLACEHOLDER_REGEX, true),
             vec![format::FormatStringPlaceholderData {
-                prefix: format!("{}|", ODD_PAD_CHAR).into(),
+                prefix: format!("{ODD_PAD_CHAR}|").into(),
                 placeholder: Some(Placeholder::NumberMinus),
                 alignment_spec: Some(Align::Left),
                 width: Some(4),
@@ -483,7 +483,7 @@ pub mod tests {
             ),
             vec![
                 format::FormatStringPlaceholderData {
-                    prefix: format!("{}|", ODD_PAD_CHAR).into(),
+                    prefix: format!("{ODD_PAD_CHAR}|").into(),
                     placeholder: Some(Placeholder::NumberMinus),
                     alignment_spec: Some(Align::Left),
                     width: Some(4),
@@ -512,7 +512,7 @@ pub mod tests {
         assert_eq!(
             format::parse_line_number_format("|++|", &LINE_NUMBERS_PLACEHOLDER_REGEX, true),
             vec![format::FormatStringPlaceholderData {
-                prefix: format!("{}", ODD_PAD_CHAR).into(),
+                prefix: format!("{ODD_PAD_CHAR}").into(),
                 placeholder: None,
                 alignment_spec: None,
                 width: None,
@@ -530,10 +530,7 @@ pub mod tests {
         let long = "line number format which is too large for SSO";
         assert!(long.len() > std::mem::size_of::<smol_str::SmolStr>());
         assert_eq!(
-            parse_line_number_format_with_default_regex(&format!(
-                "{long}{{nm}}{long}",
-                long = long
-            ),),
+            parse_line_number_format_with_default_regex(&format!("{long}{{nm}}{long}")),
             vec![format::FormatStringPlaceholderData {
                 prefix: long.into(),
                 prefix_len: long.len(),
@@ -615,7 +612,7 @@ pub mod tests {
         assert_eq!(data.formatted_width(), MinusPlus::new(32, 0));
 
         let format = MinusPlus::new("│{np:^3}│ │{nm:<12}│ │{np}│".into(), "".into());
-        let mut data = LineNumbersData::from_format_strings(&format, w.clone());
+        let mut data = LineNumbersData::from_format_strings(&format, w);
 
         data.initialize_hunk(&[(10, 11), (10000, 100001)], "a".into());
         assert_eq!(data.formatted_width(), MinusPlus::new(32, 0));
diff --git a/src/features/mod.rs b/src/features/mod.rs
index 8234d62e..dfc3582d 100644
--- a/src/features/mod.rs
+++ b/src/features/mod.rs
@@ -102,7 +102,7 @@ pub mod tests {
     fn test_builtin_features_have_flags_and_these_set_features() {
         let builtin_features = make_builtin_features();
         let mut args = vec!["delta".to_string()];
-        args.extend(builtin_features.keys().map(|s| format!("--{}", s)));
+        args.extend(builtin_features.keys().map(|s| format!("--{s}")));
         let opt = cli::Opt::from_iter_and_git_config(DeltaEnv::default(), args, None);
         let features: HashSet<&str> = opt
             .features
diff --git a/src/features/navigate.rs b/src/features/navigate.rs
index dc31e4a0..f78a6758 100644
--- a/src/features/navigate.rs
+++ b/src/features/navigate.rs
@@ -77,7 +77,7 @@ pub fn copy_less_hist_file_and_append_navigate_regex(config: &Config) -> std::io
         initial_contents
     };
     if !contents.ends_with(".search\n") {
-        contents = format!("{}.search\n", contents);
+        contents = format!("{contents}.search\n");
     }
     writeln!(
         std::fs::File::create(&delta_less_hist_file)?,
diff --git a/src/features/side_by_side.rs b/src/features/side_by_side.rs
index ac2de08e..02f3eebb 100644
--- a/src/features/side_by_side.rs
+++ b/src/features/side_by_side.rs
@@ -348,10 +348,10 @@ fn paint_right_panel_plus_line<'a>(
 }
 
 #[allow(clippy::too_many_arguments)]
-fn get_right_fill_style_for_panel<'a>(
+fn get_right_fill_style_for_panel(
     line_is_empty: bool,
     line_index: Option<usize>,
-    diff_style_sections: &[LineSections<'a, Style>],
+    diff_style_sections: &[LineSections<'_, Style>],
     lines_have_homolog: Option<&[bool]>,
     state: &State,
     panel_side: PanelSide,
@@ -468,11 +468,11 @@ fn paint_minus_or_plus_panel_line<'a>(
 /// done with spaces. The right panel can be filled with spaces or using ANSI sequences
 /// instructing the terminal emulator to fill the background color rightwards.
 #[allow(clippy::too_many_arguments, clippy::comparison_chain)]
-fn pad_panel_line_to_width<'a>(
+fn pad_panel_line_to_width(
     panel_line: &mut String,
     panel_line_is_empty: bool,
     line_index: Option<usize>,
-    diff_style_sections: &[LineSections<'a, Style>],
+    diff_style_sections: &[LineSections<'_, Style>],
     lines_have_homolog: Option<&[bool]>,
     state: &State,
     panel_side: PanelSide,
diff --git a/src/format.rs b/src/format.rs
index d40e417f..0dc05fa1 100644
--- a/src/format.rs
+++ b/src/format.rs
@@ -35,6 +35,8 @@ pub enum Align {
 impl TryFrom<Option<&str>> for Align {
     type Error = ();
     fn try_from(from: Option<&str>) -> Result<Self, Self::Error> {
+        // inlined format args are not supported for `debug_assert` with edition 2018.
+        #[allow(clippy::uninlined_format_args)]
         match from {
             Some(alignment) if alignment == "<" => Ok(Align::Left),
             Some(alignment) if alignment == ">" => Ok(Align::Right),
@@ -162,7 +164,7 @@ pub fn parse_line_number_format<'a>(
     let mut expand_first_prefix = |prefix: SmolStr| {
         // Only prefix the first placeholder with a space, also see `UseFullPanelWidth`
         if prefix_with_space {
-            let prefix = SmolStr::new(format!("{}{}", ODD_PAD_CHAR, prefix));
+            let prefix = SmolStr::new(format!("{ODD_PAD_CHAR}{prefix}"));
             prefix_with_space = false;
             prefix
         } else {
@@ -300,14 +302,14 @@ pub fn pad<T: std::fmt::Display + CenterRightNumbers>(
     let space = s.center_right_space(alignment, width);
     let mut result = match precision {
         None => match alignment {
-            Align::Left => format!("{0}{1:<2$}", space, s, width),
-            Align::Center => format!("{0}{1:^2$}", space, s, width),
-            Align::Right => format!("{0}{1:>2$}", space, s, width),
+            Align::Left => format!("{space}{s:<width$}"),
+            Align::Center => format!("{space}{s:^width$}"),
+            Align::Right => format!("{space}{s:>width$}"),
         },
         Some(precision) => match alignment {
-            Align::Left => format!("{0}{1:<2$.3$}", space, s, width, precision),
-            Align::Center => format!("{0}{1:^2$.3$}", space, s, width, precision),
-            Align::Right => format!("{0}{1:>2$.3$}", space, s, width, precision),
+            Align::Left => format!("{space}{s:<width$.precision$}"),
+            Align::Center => format!("{space}{s:^width$.precision$}"),
+            Align::Right => format!("{space}{s:>width$.precision$}"),
         },
     };
     if space == " " {
diff --git a/src/git_config/git_config_entry.rs b/src/git_config/git_config_entry.rs
index b7bd6d2f..c07fc0a0 100644
--- a/src/git_config/git_config_entry.rs
+++ b/src/git_config/git_config_entry.rs
@@ -24,16 +24,16 @@ impl GitRemoteRepo {
     pub fn format_commit_url(&self, commit: &str) -> String {
         match self {
             Self::GitHub { slug } => {
-                format!("https://github.com/{}/commit/{}", slug, commit)
+                format!("https://github.com/{slug}/commit/{commit}")
             }
             Self::GitLab { slug } => {
-                format!("https://gitlab.com/{}/-/commit/{}", slug, commit)
+                format!("https://gitlab.com/{slug}/-/commit/{commit}")
             }
             Self::SourceHut { slug } => {
-                format!("https://git.sr.ht/{}/commit/{}", slug, commit)
+                format!("https://git.sr.ht/{slug}/commit/{commit}")
             }
             Self::Codeberg { slug } => {
-                format!("https://codeberg.org/{}/commit/{}", slug, commit)
+                format!("https://codeberg.org/{slug}/commit/{commit}")
             }
         }
     }
@@ -174,7 +174,7 @@ mod tests {
         let commit_hash = "d3b07384d113edec49eaa6238ad5ff00";
         assert_eq!(
             repo.format_commit_url(commit_hash),
-            format!("https://github.com/dandavison/delta/commit/{}", commit_hash)
+            format!("https://github.com/dandavison/delta/commit/{commit_hash}")
         )
     }
 
@@ -219,7 +219,7 @@ mod tests {
         let commit_hash = "d3b07384d113edec49eaa6238ad5ff00";
         assert_eq!(
             repo.format_commit_url(commit_hash),
-            format!("https://gitlab.com/proj/grp/repo/-/commit/{}", commit_hash)
+            format!("https://gitlab.com/proj/grp/repo/-/commit/{commit_hash}")
         )
     }
 
@@ -250,10 +250,7 @@ mod tests {
         let commit_hash = "df41ac86f08a40e64c76062fd67e238522c14990";
         assert_eq!(
             repo.format_commit_url(commit_hash),
-            format!(
-                "https://git.sr.ht/~someuser/somerepo/commit/{}",
-                commit_hash
-            )
+            format!("https://git.sr.ht/~someuser/somerepo/commit/{commit_hash}")
         )
     }
 
@@ -287,7 +284,7 @@ mod tests {
         let commit_hash = "1c072856ebf12419378c5098ad543c497197c6da";
         assert_eq!(
             repo.format_commit_url(commit_hash),
-            format!("https://codeberg.org/dnkl/foot/commit/{}", commit_hash)
+            format!("https://codeberg.org/dnkl/foot/commit/{commit_hash}")
         )
     }
 }
diff --git a/src/git_config/mod.rs b/src/git_config/mod.rs
index 6b87444e..228fd4d0 100644
--- a/src/git_config/mod.rs
+++ b/src/git_config/mod.rs
@@ -51,7 +51,7 @@ impl GitConfig {
         match config {
             Some(mut config) => {
                 let config = config.snapshot().unwrap_or_else(|err| {
-                    fatal(format!("Failed to read git config: {}", err));
+                    fatal(format!("Failed to read git config: {err}"));
                 });
                 Some(Self {
                     config,
diff --git a/src/handlers/blame.rs b/src/handlers/blame.rs
index a1ec97b8..3890b7c6 100644
--- a/src/handlers/blame.rs
+++ b/src/handlers/blame.rs
@@ -363,8 +363,7 @@ pub fn parse_blame_line_numbers(arg: &str) -> BlameLineNumbers {
                 .parse::<usize>()
                 .unwrap_or_else(|err| {
                     fatal(format!(
-                        "Invalid number for blame-line-numbers in every-N argument: {}",
-                        err
+                        "Invalid number for blame-line-numbers in every-N argument: {err}",
                     ))
                 });
 
@@ -375,8 +374,7 @@ pub fn parse_blame_line_numbers(arg: &str) -> BlameLineNumbers {
             }
         }
         t => fatal(format!(
-            "Invalid format type \"{}\" for blame-line-numbers",
-            t
+            "Invalid format type \"{t}\" for blame-line-numbers",
         )),
     }
 }
@@ -529,13 +527,13 @@ mod tests {
     }
 
     fn make_blame_line_with_time(timestamp: &str) -> BlameLine {
-        let time = chrono::DateTime::parse_from_rfc3339(&timestamp).unwrap();
-        return BlameLine {
+        let time = chrono::DateTime::parse_from_rfc3339(timestamp).unwrap();
+        BlameLine {
             commit: "",
             author: "",
-            time: time,
+            time,
             line_number: 0,
             code: "",
-        };
+        }
     }
 }
diff --git a/src/handlers/diff_header.rs b/src/handlers/diff_header.rs
index 77daf843..b07e04c7 100644
--- a/