structopt to clap (#889)

Replace structopt with clap

Fixes #888

* Drop tests of deprecated options
They were failing

1 files changed, 477 insertions, 363 deletions

diff --git a/src/cli.rs b/src/cli.rs
index ed16980..cbc828b 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -2,26 +2,25 @@ use std::collections::{HashMap, HashSet};
 use std::ffi::OsString;
 use std::path::PathBuf;
 
+use clap::{AppSettings, ColorChoice, FromArgMatches, IntoApp, Parser};
 use lazy_static::lazy_static;
-use structopt::clap::AppSettings::{ColorAlways, ColoredHelp, DeriveDisplayOrder};
-use structopt::{clap, StructOpt};
 use syntect::highlighting::Theme as SyntaxTheme;
 use syntect::parsing::SyntaxSet;
 
+use crate::config::delta_unreachable;
 use crate::git_config::{GitConfig, GitConfigEntry};
 use crate::options;
 use crate::utils::bat::assets::HighlightingAssets;
 use crate::utils::bat::output::PagingMode;
 
-// No Default trait as this ignores `default_value = ..`
-#[derive(StructOpt)]
-#[structopt(
+#[derive(Parser)]
+#[clap(
     name = "delta",
     about = "A viewer for git and diff output",
-    setting(ColorAlways),
-    setting(ColoredHelp),
-    setting(DeriveDisplayOrder),
-    after_help = "\
+    version,
+    color = ColorChoice::Always,
+    setting(AppSettings::DeriveDisplayOrder),
+    after_long_help = "\
 GIT CONFIG
 ----------
 
@@ -204,632 +203,746 @@ https://github.com/dandavison/delta/issues.
 "
 )]
 pub struct Opt {
-    /// Use default colors appropriate for a light terminal background. For more control, see the
-    /// style options and --syntax-theme.
-    #[structopt(long = "light")]
+    #[clap(long = "light")]
+    /// Use default colors appropriate for a light terminal background.
+    ///
+    /// For more control, see the style options and --syntax-theme.
     pub light: bool,
 
-    /// Use default colors appropriate for a dark terminal background. For more control, see the
-    /// style options and --syntax-theme.
-    #[structopt(long = "dark")]
+    #[clap(long = "dark")]
+    /// Use default colors appropriate for a dark terminal background.
+    ///
+    /// For more control, see the style options and --syntax-theme.
     pub dark: bool,
 
-    /// Display line numbers next to the diff. See LINE NUMBERS section.
-    #[structopt(short = "n", long = "line-numbers")]
+    #[clap(short = 'n', long = "line-numbers")]
+    /// Display line numbers next to the diff.
+    ///
+    /// See LINE NUMBERS section.
     pub line_numbers: bool,
 
-    /// Display a side-by-side diff view instead of the traditional view.
-    #[structopt(short = "s", long = "side-by-side")]
+    #[clap(short = 's', long = "side-by-side")]
+    /// Display diffs in side-by-side layout.
     pub side_by_side: bool,
 
-    #[structopt(long = "diff-highlight")]
-    /// Emulate diff-highlight (https://github.com/git/git/tree/master/contrib/diff-highlight)
+    #[clap(long = "diff-highlight")]
+    /// Emulate diff-highlight.
+    ///
+    /// (https://github.com/git/git/tree/master/contrib/diff-highlight)
     pub diff_highlight: bool,
 
-    #[structopt(long = "diff-so-fancy")]
-    /// Emulate diff-so-fancy (https://github.com/so-fancy/diff-so-fancy)
+    #[clap(long = "diff-so-fancy")]
+    /// Emulate diff-so-fancy.
+    ///
+    /// (https://github.com/so-fancy/diff-so-fancy)
     pub diff_so_fancy: bool,
 
-    #[structopt(long = "navigate")]
-    /// Activate diff navigation: use n to jump forwards and N to jump backwards. To change the
-    /// file labels used see --file-modified-label, --file-removed-label, --file-added-label,
-    /// --file-renamed-label.
+    #[clap(long = "navigate")]
+    /// Activate diff navigation.
+    ///
+    /// Use n to jump forwards and N to jump backwards. To change the file labels used see
+    /// --file-modified-label, --file-removed-label, --file-added-label, --file-renamed-label.
     pub navigate: bool,
 
-    #[structopt(long = "relative-paths")]
-    /// Output all file paths relative to the current directory so that they
-    /// resolve correctly when clicked on or used in shell commands.
+    #[clap(long = "relative-paths")]
+    /// Output all file paths relative to the current directory.
+    ///
+    /// This means that they will resolve correctly when clicked on or used in shell commands.
     pub relative_paths: bool,
 
-    #[structopt(long = "hyperlinks")]
-    /// Render commit hashes, file names, and line numbers as hyperlinks,
-    /// according to the hyperlink spec for terminal emulators:
-    /// https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda. By
-    /// default, file names and line numbers link to the local file using a file
-    /// URL, whereas commit hashes link to the commit in GitHub, if the remote
-    /// repository is hosted by GitHub. See --hyperlinks-file-link-format for
-    /// full control over the file URLs emitted. Hyperlinks are supported by
-    /// several common terminal emulators. To make them work, you must use less
-    /// version >= 581 with the -R flag (or use -r with older less versions, but
-    /// this will break e.g. --navigate). If you use tmux, then you will also
-    /// need a patched fork of tmux (see https://github.com/dandavison/tmux).
+    #[clap(long = "hyperlinks")]
+    /// Render commit hashes, file names, and line numbers as hyperlinks.
+    ///
+    /// Following the hyperlink spec for terminal emulators:
+    /// https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda. By default, file names
+    /// and line numbers link to the local file using a file URL, whereas commit hashes link to the
+    /// commit in GitHub, if the remote repository is hosted by GitHub. See
+    /// --hyperlinks-file-link-format for full control over the file URLs emitted. Hyperlinks are
+    /// supported by several common terminal emulators. To make them work, you must use less version
+    /// >= 581 with the -R flag (or use -r with older less versions, but this will break e.g.
+    /// --navigate). If you use tmux, then you will also need a patched fork of tmux (see
+    /// https://github.com/dandavison/tmux).
     pub hyperlinks: bool,
 
-    #[structopt(long = "keep-plus-minus-markers")]
-    /// Prefix added/removed lines with a +/- character, exactly as git does. By default, delta
-    /// does not emit any prefix, so code can be copied directly from delta's output.
+    #[clap(long = "keep-plus-minus-markers")]
+    /// Prefix added/removed lines with a +/- character, as git does.
+    ///
+    /// By default, delta does not emit any prefix, so code can be copied directly from delta's
+    /// output.
     pub keep_plus_minus_markers: bool,
 
-    /// Display the active values for all Delta options. Style options are displayed with
-    /// foreground and background colors. This can be used to experiment with colors by combining
-    /// this option with other options such as --minus-style, --zero-style, --plus-style, --light,
-    /// --dark, etc.
-    #[structopt(long = "show-config")]
+    #[clap(long = "show-config")]
+    /// Display the active values for all Delta options.
+    ///
+    /// Style string options are displayed with foreground and background colors. This can be used to
+    /// experiment with colors by combining this option with other options such as --minus-style,
+    /// --zero-style, --plus-style, --light, --dark, etc.
     pub show_config: bool,
 
+    #[clap(long = "list-languages")]
     /// List supported languages and associated file extensions.
-    #[structopt(long = "list-languages")]
     pub list_languages: bool,
 
+    #[clap(long = "list-syntax-themes")]
     /// List available syntax-highlighting color themes.
-    #[structopt(long = "list-syntax-themes")]
     pub list_syntax_themes: bool,
 
-    /// Show all available syntax-highlighting themes, each with an example of highlighted diff output.
+    #[clap(long = "show-syntax-themes")]
+    /// Show example diff for available syntax-highlighting themes.
+    ///
     /// If diff output is supplied on standard input then this will be used for the demo. For
     /// example: `git show | delta --show-syntax-themes`.
-    #[structopt(long = "show-syntax-themes")]
     pub show_syntax_themes: bool,
 
-    /// Show available delta themes, each with an example of highlighted diff
-    /// output. A delta theme is a delta named feature (see --features) that
-    /// sets either `light` or `dark`. See
-    /// https://github.com/dandavison/delta#custom-color-themes. If diff output
-    /// is supplied on standard input then this will be used for the demo. For
-    /// example: `git show | delta --show-themes`. By default shows dark or
-    /// light themes only, according to whether delta is in dark or light mode
-    /// (as set by the user or inferred from BAT_THEME). To control the themes
-    /// shown, use --dark or --light, or both, on the command line together with
-    /// this option.
-    #[structopt(long = "show-themes")]
+    #[clap(long = "show-themes")]
+    /// Show example diff for available delta themes.
+    ///
+    /// A delta theme is a delta named feature (see --features) that sets either `light` or `dark`.
+    /// See https://github.com/dandavison/delta#custom-color-themes. If diff output is supplied on
+    /// standard input then this will be used for the demo. For example: `git show | delta
+    /// --show-themes`. By default shows dark or light themes only, according to whether delta is in
+    /// dark or light mode (as set by the user or inferred from BAT_THEME). To control the themes
+    /// shown, use --dark or --light, or both, on the command line together with this option.
     pub show_themes: bool,
 
-    /// Show available named colors. In addition to named colors, arbitrary
-    /// colors can be specified using RGB hex codes. See COLORS section.
-    #[structopt(long = "show-colors")]
+    #[clap(long = "show-colors")]
+    /// Show available named colors.
+    ///
+    /// In addition to named colors, arbitrary colors can be specified using RGB hex codes. See
+    /// COLORS section.
     pub show_colors: bool,
 
-    /// Parse ANSI color escape sequences in input and display them as git style
-    /// strings. Example usage: git show --color=always | delta --parse-ansi
+    #[clap(long = "parse-ansi")]
+    /// Display ANSI color escape sequences in human-readable form.
+    ///
+    /// Example usage: git show --color=always | delta --parse-ansi
     /// This can be used to help identify input style strings to use with map-styles.
-    #[structopt(long = "parse-ansi")]
     pub parse_ansi: bool,
 
-    #[structopt(long = "no-gitconfig")]
-    /// Do not take any settings from git config. See GIT CONFIG section.
+    #[clap(long = "no-gitconfig")]
+    /// Do not read any settings from git config.
+    ///
+    /// See GIT CONFIG section.
     pub no_gitconfig: bool,
 
-    #[structopt(long = "raw")]
-    /// Do not alter the input in any way. This is mainly intended for testing delta.
+    #[clap(long = "raw")]
+    /// Do not alter the input in any way.
+    ///
+    /// This is mainly intended for testing delta.
     pub raw: bool,
 
-    #[structopt(long = "color-only")]
-    /// Do not alter the input structurally in any way, but color and highlight hunk lines
-    /// according to your delta configuration. This is mainly intended for other tools that use
-    /// delta.
+    #[clap(long = "color-only")]
+    /// Do not alter the input structurally in any way.
+    ///
+    /// But color and highlight hunk lines according to your delta configuration. This is mainly
+    /// intended for other tools that use delta.
     pub color_only: bool,
 
     ////////////////////////////////////////////////////////////////////////////////////////////
-    #[structopt(long = "features")]
-    /// Name of delta features to use (space-separated). A feature is a named collection of delta
-    /// options in ~/.gitconfig. See FEATURES section. The environment variable DELTA_FEATURES can
-    /// be set to a space-separated list of feature names. If this is preceded with a space, the
-    /// features from the environment variable will be added to those specified in git config. E.g.
-    /// DELTA_FEATURES=+side-by-side can be used to activate side-by-side temporarily.
+    #[clap(long = "features")]
+    /// Names of delta features to activate (space-separated).
+    ///
+    /// A feature is a named collection of delta options in ~/.gitconfig. See FEATURES section. The
+    /// environment variable DELTA_FEATURES can be set to a space-separated list of feature names.
+    /// If this is preceded with a space, the features from the environment variable will be added
+    /// to those specified in git config. E.g. DELTA_FEATURES=+side-by-side can be used to activate
+    /// side-by-side temporarily.
     pub features: Option<String>,
 
-    #[structopt(long = "syntax-theme")]
-    /// The code syntax-highlighting theme to use. Use --show-syntax-themes to demo available
-    /// themes. Defaults to the value of the BAT_THEME environment variable, if that contains a
-    /// valid theme name. --syntax-theme=none disables all syntax highlighting.
+    #[clap(long = "syntax-theme")]
+    /// The syntax-highlighting theme to use.
+    ///
+    /// Use --show-syntax-themes to demo available themes. Defaults to the value of the BAT_THEME
+    /// environment variable, if that contains a valid theme name. --syntax-theme=none disables all
+    /// syntax highlighting.
     pub syntax_theme: Option<String>,
 
-    #[structopt(long = "minus-style", default_value = "normal auto")]
-    /// Style (foreground, background, attributes) for removed lines. See STYLES section.
+    #[clap(long = "minus-style", default_value = "normal auto")]
+    /// Style string for removed lines.
+    ///
+    /// See STYLES section.
     pub minus_style: String,
 
-    #[structopt(long = "zero-style", default_value = "syntax normal")]
-    /// Style (foreground, background, attributes) for unchanged lines. See STYLES section.
+    #[clap(long = "zero-style", default_value = "syntax normal")]
+    /// Style string for unchanged lines.
+    ///
+    /// See STYLES section.
     pub zero_style: String,
 
-    #[structopt(long = "plus-style", default_value = "syntax auto")]
-    /// Style (foreground, background, attributes) for added lines. See STYLES section.
+    #[clap(long = "plus-style", default_value = "syntax auto")]
+    /// Style string for added lines.
+    ///
+    /// See STYLES section.
     pub plus_style: String,
 
-    #[structopt(long = "minus-emph-style", default_value = "normal auto")]
-    /// Style (foreground, background, attributes) for emphasized sections of removed lines. See
-    /// STYLES section.
+    #[clap(long = "minus-emph-style", default_value = "normal auto")]
+    /// Style string for emphasized sections of removed lines.
+    ///
+    /// See STYLES section.
     pub minus_emph_style: String,
 
-    #[structopt(long = "minus-non-emph-style", default_value = "minus-style")]
-    /// Style (foreground, background, attributes) for non-emphasized sections of removed lines
-    /// that have an emphasized section. See STYLES section.
+    #[clap(long = "minus-non-emph-style", default_value = "minus-style")]
+    /// Style string for non-emphasized sections of removed lines that have an emphasized section.
+    ///
+    /// See STYLES section.
     pub minus_non_emph_style: String,
 
-    #[structopt(long = "plus-emph-style", default_value = "syntax auto")]
-    /// Style (foreground, background, attributes) for emphasized sections of added lines. See
-    /// STYLES section.
+    #[clap(long = "plus-emph-style", default_value = "syntax auto")]
+    /// Style string for emphasized sections of added lines.
+    ///
+    /// See STYLES section.
     pub plus_emph_style: String,
 
-    #[structopt(long = "plus-non-emph-style", default_value = "plus-style")]
-    /// Style (foreground, background, attributes) for non-emphasized sections of added lines that
-    /// have an emphasized section. See STYLES section.
+    #[clap(long = "plus-non-emph-style", default_value = "plus-style")]
+    /// Style string for non-emphasized sections of added lines that have an emphasized section.
+    ///
+    /// See STYLES section.
     pub plus_non_emph_style: String,
 
-    #[structopt(long = "commit-style", default_value = "raw")]
-    /// Style (foreground, background, attributes) for the commit hash line. See STYLES section.
-    /// The style 'omit' can be used to remove the commit hash line from the output.
+    #[clap(long = "commit-style", default_value = "raw")]
+    /// Style string for the commit hash line.
+    ///
+    /// See STYLES section. The style 'omit' can be used to remove the commit hash line from the
+    /// output.
     pub commit_style: String,
 
-    #[structopt(long = "commit-decoration-style", default_value = "")]
-    /// Style (foreground, background, attributes) for the commit hash decoration. See STYLES
-    /// section. The style string should contain one of the special attributes 'box', 'ul'
-    /// (underline), 'ol' (overline), or the combination 'ul ol'.
+    #[clap(long = "commit-decoration-style", default_value = "")]
+    /// Style string for the commit hash decoration.
+    ///
+    /// See STYLES section. The style string should contain one of the special attributes 'box',
+    /// 'ul' (underline), 'ol' (overline), or the combination 'ul ol'.
     pub commit_decoration_style: String,
 
-    /// The regular expression used to identify the commit line when parsing git output.
-    #[structopt(long = "commit-regex", default_value = r"^commit ")]
+    #[clap(long = "commit-regex", default_value = r"^commit ")]
+    /// Regular expression used to identify the commit line when parsing git output.
     pub commit_regex: String,
 
-    #[structopt(long = "file-style", default_value = "blue")]
-    /// Style (foreground, background, attributes) for the file section. See STYLES section. The
-    /// style 'omit' can be used to remove the file section from the output.
+    #[clap(long = "file-style", default_value = "blue")]
+    /// Style string for the file section.
+    ///
+    /// See STYLES section. The style 'omit' can be used to remove the file section from the output.
     pub file_style: String,
 
-    #[structopt(long = "file-decoration-style", default_value = "blue ul")]
-    /// Style (foreground, background, attributes) for the file decoration. See STYLES section. The
-    /// style string should contain one of the special attributes 'box', 'ul' (underline), 'ol'
-    /// (overline), or the combination 'ul ol'.
+    #[clap(long = "file-decoration-style", default_value = "blue ul")]
+    /// Style string for the file decoration.
+    ///
+    /// See STYLES section. The style string should contain one of the special attributes 'box',
+    /// 'ul' (underline), 'ol' (overline), or the combination 'ul ol'.
     pub file_decoration_style: String,
 
     #[structopt(long = "file-transformation")]
-    /// A sed-style command specifying how file paths should be transformed for display.
+    /// A sed-style command transforming file paths for display.
     pub file_regex_replacement: Option<String>,
 
-    /// Format string for commit hyperlinks (requires --hyperlinks). The
-    /// placeholder "{commit}" will be replaced by the commit hash. For example:
+    #[clap(long = "hyperlinks-commit-link-format")]
+    /// Format string for commit hyperlinks (requires --hyperlinks).
+    ///
+    /// The placeholder "{commit}" will be replaced by the commit hash. For example:
     /// --hyperlinks-commit-link-format='https://mygitrepo/{commit}/'
-    #[structopt(long = "hyperlinks-commit-link-format")]
     pub hyperlinks_commit_link_format: Option<String>,
 
-    /// Format string for file hyperlinks (requires --hyperlinks). The
-    /// placeholders "{path}" and "{line}" will be replaced by the absolute file
-    /// path and the line number, respectively. The default value of this option
-    /// creates hyperlinks using standard file URLs; your operating system
-    /// should open these in the application registered for that file type.
-    /// However, these do not make use of the line number. In order for the link
-    /// to open the file at the correct line number, you could use a custom URL
-    /// format such as "file-line://{path}:{line}" and register an application
-    /// to handle the custom "file-line" URL scheme by opening the file in your
-    /// editor/IDE at the indicated line number. See
+    #[clap(long = "hyperlinks-file-link-format", default_value = "file://{path}")]
+    /// Format string for file hyperlinks (requires --hyperlinks).
+    ///
+    /// The placeholders "{path}" and "{line}" will be replaced by the absolute file path and the
+    /// line number, respectively. The default value of this option creates hyperlinks using
+    /// standard file URLs; your operating system should open these in the application registered
+    /// for that file type. However, these do not make use of the line number. In order for the link
+    /// to open the file at the correct line number, you could use a custom URL format such as
+    /// "file-line://{path}:{line}" and register an application to handle the custom "file-line" URL
+    /// scheme by opening the file in your editor/IDE at the indicated line number. See
     /// https://github.com/dandavison/open-in-editor for an example.
-    #[structopt(long = "hyperlinks-file-link-format", default_value = "file://{path}")]
     pub hyperlinks_file_link_format: String,
 
-    #[structopt(long = "hunk-header-style", default_value = "line-number syntax")]
-    /// Style (foreground, background, attributes) for the hunk-header. See STYLES section. Special
-    /// attributes 'file' and 'line-number' can be used to include the file path, and number of
-    /// first hunk line, in the hunk header. The style 'omit' can be used to remove the hunk header
-    /// section from the output.
+    #[clap(long = "hunk-header-style", default_value = "line-number syntax")]
+    /// Style string for the hunk-header.
+    ///
+    /// See STYLES section. Special attributes 'file' and 'line-number' can be used to include the
+    /// file path, and number of first hunk line, in the hunk header. The style 'omit' can be used
+    /// to remove the hunk header section from the output.
     pub hunk_header_style: String,
 
-    #[structopt(long = "hunk-header-file-style", default_value = "blue")]
-    /// Style (foreground, background, attributes) for the file path part of the hunk-header. See
-    /// STYLES section. The file path will only be displayed if hunk-header-style contains the
+    #[clap(long = "hunk-header-file-style", default_value = "blue")]
+    /// Style string for the file path part of the hunk-header.
+    ///
+    /// See STYLES section. The file path will only be displayed if hunk-header-style contains the
     /// 'file' special attribute.
     pub hunk_header_file_style: String,
 
-    #[structopt(long = "hunk-header-line-number-style", default_value = "blue")]
-    /// Style (foreground, background, attributes) for the line number part of the hunk-header. See
-    /// STYLES section. The line number will only be displayed if hunk-header-style contains the
+    #[clap(long = "hunk-header-line-number-style", default_value = "blue")]
+    /// Style string for the line number part of the hunk-header.
+    ///
+    /// See STYLES section. The line number will only be displayed if hunk-header-style contains the
     /// 'line-number' special attribute.
     pub hunk_header_line_number_style: String,
 
-    #[structopt(long = "hunk-header-decoration-style", default_value = "blue box")]
-    /// Style (foreground, background, attributes) for the hunk-header decoration. See STYLES
-    /// section. The style string should contain one of the special attributes 'box', 'ul'
-    /// (underline), 'ol' (overline), or the combination 'ul ol'.
+    #[clap(long = "hunk-header-decoration-style", default_value = "blue box")]
+    /// Style string for the hunk-header decoration.
+    ///
+    /// See STYLES section. The style string should contain one of the special attributes 'box',
+    /// 'ul' (underline), 'ol' (overline), or the combination 'ul ol'.
     pub hunk_header_decoration_style: String,
 
-    #[structopt(long = "merge-conflict-begin-symbol", default_value = "▼")]
-    /// A string that is repeated to form the line marking the beginning of a merge conflict region.
+    #[clap(long = "merge-conflict-begin-symbol", default_value = "▼")]
+    /// String marking the beginning of a merge conflict region.
+    ///
+    /// The string will be repeated until it reaches the required length.
     pub merge_conflict_begin_symbol: String,
 
-    #[structopt(long = "merge-conflict-end-symbol", default_value = "▲")]
-    /// A string that is repeated to form the line marking the end of a merge conflict region.
+    #[clap(long = "merge-conflict-end-symbol", default_value = "▲")]
+    /// String marking the end of a merge conflict region.
+    ///
+    /// The string will be repeated until it reaches the required length.
     pub merge_conflict_end_symbol: String,
 
-    #[structopt(
+    #[clap(
         long = "merge-conflict-ours-diff-header-style",
         default_value = "normal"
     )]
-    /// Style (foreground, background, attributes) for the header above the diff between the
-    /// ancestral commit and 'our' branch. See STYLES section.
+    /// Style string for the header above the 'ours' branch merge conflict diff.
+    ///
+    /// See STYLES section.
     pub merge_conflict_ours_diff_header_style: String,
 
-    #[structopt(
+    #[clap(
         long = "merge-conflict-ours-diff-header-decoration-style",
         default_value = "box"
     )]
-    /// Style (foreground, background, attributes) for the decoration of the header above the diff
-    /// between the ancestral commit and 'our' branch.  See STYLES section. The style string should
-    /// contain one of the special attributes 'box', 'ul' (underline), 'ol' (overline), or the
-    /// combination 'ul ol'.
+    /// Style string for the decoration of the header above the 'ours' merge conflict diff.
+    ///
+    /// This styles the decoration of the header above the diff between the ancestral commit and the
+    /// 'ours' branch. See STYLES section. The style string should contain one of the special
+    /// attributes 'box', 'ul' (underline), 'ol' (overline), or the combination 'ul ol'.
     pub merge_conflict_ours_diff_header_decoration_style: String,
 
-    #[structopt(
+    #[clap(
         long = "merge-conflict-theirs-diff-header-style",
         default_value = "normal"
     )]
-    /// Style (foreground, background, attributes) for the header above the diff between the
-    /// ancestral commit and 'their' branch. See STYLES section.
+    /// Style string for the header above the 'theirs' branch merge conflict diff.
+    ///
+    /// This styles the header above the diff between the ancestral commit and 'their' branch. See
+    /// STYLES section.
     pub merge_conflict_theirs_diff_header_style: String,
 
-    #[structopt(
+    #[clap(
         long = "merge-conflict-theirs-diff-header-decoration-style",
         default_value = "box"
     )]
-    /// Style (foreground, background, attributes) for the decoration of the header above the diff
-    /// between the ancestral commit and 'their' branch.  See STYLES section. The style string should
-    /// contain one of the special attributes 'box', 'ul' (underline), 'ol' (overline), or the
-    /// combination 'ul ol'.
+    /// Style string for the decoration of the header above the 'theirs' merge conflict diff.
+    ///
+    /// This styles the decoration of the header above the diff between the ancestral commit and
+    /// 'their' branch.  See STYLES section. The style string should contain one of the special
+    /// attributes 'box', 'ul' (underline), 'ol' (overline), or the combination 'ul ol'.
     pub merge_conflict_theirs_diff_header_decoration_style: String,
 
-    #[structopt(long = "map-styles")]
-    /// A string specifying a mapping styles encountered in raw input to desired
-    /// output styles. An example is
-    /// --map-styles='bold purple => red "#eeeeee", bold cyan => syntax "#eeeeee"'
+    #[clap(long = "map-styles")]
+    /// Map styles encountered in raw input to desired output styles.
+    ///
+    /// An example is --map-styles='bold purple => red "#eeeeee", bold cyan => syntax "#eeeeee"'
     pub map_styles: Option<String>,
 
-    /// Format string for git blame commit metadata. Available placeholders are
-    /// "{timestamp}", "{author}", and "{commit}".
-    #[structopt(
+    #[clap(
         long = "blame-format",
         default_value = "{timestamp:<15} {author:<15.14} {commit:<8}"
     )]
+    /// Format string for git blame commit metadata.
+    ///
+    /// Available placeholders are "{timestamp}", "{author}", and "{commit}".
     pub blame_format: String,
 
-    /// Separator between the commit metadata and code sections of a line of git blame output.
-    #[structopt(long = "blame-separator", default_value = "│")]
+    #[clap(long = "blame-separator", default_value = "│")]
+    /// Separator between the commit metadata and code sections of a git blame line.
     pub blame_separator: String,
 
-    #[structopt(long = "blame-separator-style")]
-    /// Style (foreground, background, attributes) for the separator between the commit metadata and
-    /// code sections of a line of `git blame` output.
+    #[clap(long = "blame-separator-style")]
+    /// Style string for the separator between the commit metadata and code sections of a git blame line.
     pub blame_separator_style: Option<String>,
 
-    #[structopt(long = "blame-code-style")]
-    /// Style (foreground, background, attributes) for the code section of a line of `git blame`
-    /// output. By default the code will be syntax-highlighted with the same background color as the
-    /// blame format section of the line (the background color is determined by blame-palette). E.g.
+    #[clap(long = "blame-code-style")]
+    /// Style string for the code section of a git blame line.
+    ///
+    /// By default the code will be syntax-highlighted with the same background color as the blame
+    /// format section of the line (the background color is determined by blame-palette). E.g.
     /// setting this option to 'syntax' will syntax-highlight the code with no background color.
     pub blame_code_style: Option<String>,
 
+    #[clap(long = "blame-palette")]
     /// Background colors used for git blame lines (space-separated string).
-    /// Lines added by the same commit are painted with the same color; colors
-    /// are recycled as needed.
-    #[structopt(long = "blame-palette")]
+    ///
+    /// Lines added by the same commit are painted with the same color; colors are recycled as
+    /// needed.
     pub blame_palette: Option<String>,
 
-    /// Format of `git blame` timestamp in raw git output received by delta.
-    #[structopt(
+    #[clap(
         long = "blame-timestamp-format",
         default_value = "%Y-%m-%d %H:%M:%S %z"
     )]
+    /// Format of `git blame` timestamp in raw git output received by delta.
     pub blame_timestamp_format: String,
 
-    #[structopt(long = "grep-match-line-style")]
-    /// Style (foreground, background, attributes) for matching lines of code in
-    /// grep output. See STYLES section. Defaults to plus-style.
+    #[clap(long = "grep-match-line-style")]
+    /// Style string for matching lines of grep output.
+    ///
+    /// See STYLES section. Defaults to plus-style.
     pub grep_match_line_style: Option<String>,
 
-    #[structopt(long = "grep-match-word-style")]
-    /// Style (foreground, background, attributes) for the specific matching
-    /// substrings within a matching line of code in grep output. See STYLES
-    /// section. Defaults to plus-style.
+    #[clap(long = "grep-match-word-style")]
+    /// Style string for the matching substrings within a matching line of grep output.
+    ///
+    /// See STYLES section. Defaults to plus-style.
     pub grep_match_word_style: Option<String>,
 
-    #[structopt(long = "grep-context-line-style")]
-    /// Style (foreground, background, attributes) for non-matching lines of
-    /// code in grep output. See STYLES section. Defaults to zero-style.
+    #[clap(long = "grep-context-line-style")]
+    /// Style string for non-matching lines of grep output.
+    ///
+    /// See STYLES section. Defaults to zero-style.
     pub grep_context_line_style: Option<String>,
 
-    #[structopt(long = "grep-file-style")]
-    /// Style (foreground, background, attributes) for file paths in grep
-    /// output. See STYLES section. Defaults to hunk-header-file-path-style.
+    #[clap(long = "grep-file-style")]
+    /// Style string for file paths in grep output.
+    ///
+    /// See STYLES section. Defaults to hunk-header-file-path-style.
     pub grep_file_style: Option<String>,
 
-    #[structopt(long = "grep-line-number-style")]
-    /// Style (foreground, background, attributes) for line numbers in grep
-    /// output. See STYLES section. Defaults to hunk-header-line-number-style.
+    #[clap(long = "grep-line-number-style")]
+    /// Style string for line numbers in grep output.
+    ///
+    /// See STYLES section. Defaults to hunk-header-line-number-style.
     pub grep_line_number_style: Option<String>,
 
-    #[structopt(long = "grep-separator-symbol", default_value = ":")]
-    /// Symbol used in grep output to separate file path (and line number) from
-    /// the line of file contents. Defaults to ":" for both match and context
-    /// lines, since many terminal emulators recognize constructs like
-    /// "/path/to/file:7:". However, standard grep output uses "-" for context
+    #[clap(long = "grep-separator-symbol", default_value = ":")]
+    /// Separator symbol printed after the file path and line number in grep output.
+    ///
+    /// Defaults to ":" for both match and context lines, since many terminal emulators recognize
+    /// constructs like "/path/to/file:7:". However, standard grep output uses "-" for context
     /// lines: set this option to "keep" to keep the original separator symbols.
     pub grep_separator_symbol: String,
 
-    /// Default language used for syntax highlighting when this cannot be
-    /// inferred from a filename. It will typically make sense to set this in
-    /// per-repository git config (.git/config)
-    #[structopt(long = "default-language")]
+    #[clap(long = "default-language")]
+    /// Default language used for syntax highlighting.
+    ///
+    /// Used when the language cannot be inferred from a filename. It will typically make sense to
+    /// set this in per-repository git config (.git/config)
     pub default_language: Option<String>,
 
-    #[structopt(long = "inline-hint-style", default_value = "blue")]
-    /// Style (foreground, background, attributes) for content added by delta to
-    /// the original diff such as special characters to highlight tabs, and the
-    /// symbols used to indicate wrapped lines. See STYLES section.
+    #[clap(long = "inline-hint-style", default_value = "blue")]
+    /// Style string for short inline hint text.
+    ///
+    /// This styles certain content added by delta to the original diff such as special characters
+    /// to highlight tabs, and the symbols used to indicate wrapped lines. See STYLES section.
     pub inline_hint_style: String,
 
+    #[clap(long = "word-diff-regex", default_value = r"\w+")]
+    /// Regular expression defining a 'word' in within-line diff algorithm.
+    ///
     /// The regular expression used to decide what a word is for the within-line highlight
     /// algorithm. For less fine-grained matching than the default try --word-diff-regex="\S+"
     /// --max-line-distance=1.0 (this is more similar to `git --word-diff`).
-    #[structopt(long = "word-diff-regex", default_value = r"\w+")]
     pub tokenization_regex: String,
 
-    /// The maximum distance between two lines for them to be inferred to be homologous. Homologous
-    /// line pairs are highlighted according to the deletion and insertion operations transforming
-    /// one into the other.
-    #[structopt(long = "max-line-distance", default_value = "0.6")]
+    #[clap(long = "max-line-distance", default_value = "0.6")]
+    /// Maximum line pair distance parameter in within-line diff algorithm.
+    ///
+    /// This parameter is the maximum distance (0.0 - 1.0) between two lines for them to be inferred
+    /// to be homologous. Homologous line pairs are highlighted according to the deletion and
+    /// insertion operations transforming one into the other.
     pub max_line_distance: f64,
 
-    /// Style (foreground, background, attributes) for line numbers in the old (minus) version of
-    /// the file. See STYLES and LINE NUMBERS sections.
-    #[structopt(long = "line-numbers-minus-style", default_value = "auto")]
+    #[clap(long = "line-numbers-minus-style", default_value = "auto")]
+    /// Style string for line numbers in the old (minus) version of the file.
+    ///
+    /// See STYLES and LINE NUMBERS sections.
     pub line_numbers_minus_style: String,
 
-    /// Style (foreground, background, attributes) for line numbers in unchanged (zero) lines. See
-    /// STYLES and LINE NUMBERS sections.
-    #[structopt(long = "line-numbers-zero-style", default_value = "auto")]
+    #[clap(long = "line-numbers-zero-style", default_value = "auto")]
+    /// Style string for line numbers in unchanged (zero) lines.
+    ///
+    /// See STYLES and LINE NUMBERS sections.
     pub line_numbers_zero_style: String,
 
-    /// Style (foreground, background, attributes) for line numbers in the new (plus) version of
-    /// the file. See STYLES and LINE NUMBERS sections.
-    #[structopt(long = "line-numbers-plus-style", default_value = "auto")]
+    #[clap(long = "line-numbers-plus-style", default_value = "auto")]
+    /// Style string for line numbers in the new (plus) version of the file.
+    ///
+    /// See STYLES and LINE NUMBERS sections.
     pub line_numbers_plus_style: String,
 
-    /// Format string for the left column of line numbers. A typical value would be "{nm:^4}⋮"
-    /// which means to display the line numbers of the minus file (old version), center-aligned,
-    /// padded to a width of 4 characters, followed by a dividing character. See the LINE NUMBERS
-    /// section.
-    #[structopt(long = "line-numbers-left-format", default_value = "{nm:^4}⋮")]
+    #[clap(long = "line-numbers-left-format", default_value = "{nm:^4}⋮")]
+    /// Format string for the left column of line numbers.
+    ///
+    /// A typical value would be "{nm:^4}⋮" which means to display the line numbers of the minus
+    /// file (old version), center-aligned, padded to a width of 4 characters, followed by a
+    /// dividing character. See the LINE NUMBERS section.
     pub line_numbers_left_format: String,
 
-    /// Format string for the right column of line numbers. A typical value would be "{np:^4}│ "
-    /// which means to display the line numbers of the plus file (new version), center-aligned,
-    /// padded to a width of 4 characters, followed by a dividing character, and a space. See the
-    /// LINE NUMBERS section.
-    #[structopt(long = "line-numbers-right-format", default_value = "{np:^4}│")]
+    #[clap(long = "line-numbers-right-format", default_value = "{np:^4}│")]
+    /// Format string for the right column of line numbers.
+    ///
+    /// A typical value would be "{np:^4}│ " which means to display the line numbers of the plus
+    /// file (new version), center-aligned, padded to a width of 4 characters, followed by a
+    /// dividing character, and a space. See the LINE NUMBERS section.
     pub line_numbers_right_format: String,
 
-    /// Style (foreground, background, attributes) for the left column of line numbers. See STYLES
-    /// and LINE NUMBERS sections.
-    #[structopt(long = "line-numbers-left-style", default_value = "auto")]
+    #[clap(long = "line-numbers-left-style", default_value = "auto")]
+    /// Style string for the left column of line numbers.
+    ///
+    /// See STYLES and LINE NUMBERS sections.
     pub line_numbers_left_style: String,
 
-    /// Style (foreground, background, attributes) for the right column of line numbers. See STYLES
-    /// and LINE NUMBERS sections.
-    #[structopt(long = "line-numbers-right-style", default_value = "auto")]
+    #[clap(long = "line-numbers-right-style", default_value = "auto")]
+    /// Style string for the right column of line numbers.
+    ///
+    /// See STYLES and LINE NUMBERS sections.
     pub line_numbers_right_style: String,
 
-    /// How often a line should be wrapped if it does not fit. Zero means to never wrap. Any content
-    /// which does not fit will be truncated. A value of "unlimited" means a line will be wrapped
-    /// as many times as required.
-    #[structopt(long = "wrap-max-lines", default_value = "2")]
+    #[clap(long = "wrap-max-lines", default_value = "2")]
+    /// How often a line should be wrapped if it does not fit.
+    ///
+    /// Zero means to never wrap. Any content which does not fit will be truncated. A value of
+    /// "unlimited" means a line will be wrapped as many times as required.
     pub wrap_max_lines: String,
 
-    /// Symbol added to the end of a line indicating that the content has been wrapped
-    /// onto the next line and continues left-aligned.
-    #[structopt(long = "wrap-left-symbol", default_value = "↵")]
+    #[clap(long = "wrap-left-symbol", default_value = "↵")]
+    /// End-of-line wrapped content symbol (left-aligned).
+    ///
+    /// Symbol added to the end of a line indicating that the content has been wrapped onto the next
+    /// line and continues left-aligned.
     pub wrap_left_symbol: String,
 
-    /// Symbol added to the end of a line indicating that the content has been wrapped
-    /// onto the next line and continues right-aligned.
-    #[structopt(long = "wrap-right-symbol", default_value = "↴")]
+    #[clap(long = "wrap-right-symbol", default_value = "↴")]
+    /// End-of-line wrapped content symbol (right-aligned).
+    ///
+    /// Symbol added to the end of a line indicating that the content has been wrapped onto the next
+    /// line and continues right-aligned.
     pub wrap_right_symbol: String,
 
-    /// Threshold for right-aligning wrapped content. If the length of the remaining wrapped
-    /// content, as a percentage of width, is less than this quantity it will be right-aligned.
-    /// Otherwise it will be left-aligned.
-    #[structopt(long = "wrap-right-percent", default_value = "37.0")]
+    #[clap(long = "wrap-right-percent", default_value = "37.0")]
+    /// Threshold for right-aligning wrapped content.
+    ///
+    /// If the length of the remaining wrapped content, as a percentage of width, is less than this
+    /// quantity it will be right-aligned. Otherwise it will be left-aligned.
     pub wrap_right_percent: String,
 
+    #[clap(long = "wrap-right-prefix-symbol", default_value = "…")]
+    /// Pre-wrapped content symbol (right-aligned).
+    ///
     /// Symbol displayed in front of right-aligned wrapped content.
-    #[structopt(long = "wrap-right-prefix-symbol", default_value = "…")]
     pub wrap_right_prefix_symbol: String,
 
-    #[structopt(long = "navigate-regex")]
-    /// A regexp to use in the less pager when navigating (auto-generated when unspecified)
+    #[clap(long = "navigate-regex")]
+    /// Regular expression defining navigation stop points.
     pub navigate_regex: Option<String>,
 
-    #[structopt(long = "file-modified-label", default_value = "")]
+    #[clap(long = "file-modified-label", default_value = "")]
     /// Text to display in front of a modified file path.
+    ///
+    /// Used in the default value of navigate-regex.
     pub file_modified_label: String,
 
-    #[structopt(long = "file-removed-label", default_value = "removed:")]
+    #[clap(long = "file-removed-label", default_value = "removed:")]
     /// Text to display in front of a removed file path.
+    ///
+    /// Used in the default value of navigate-regex.
     pub file_removed_label: String,
 
-    #[structopt(long = "file-added-label", default_value = "added:")]
-    /// Text to display in front of a added file path.
+    #[clap(long = "file-added-label", default_value = "added:")]
+    /// Text to display in front of an added file path.
+    ///
+    /// Used in the default value of navigate-regex.
     pub file_added_label: String,
 
-    #[structopt(long = "file-copied-label", default_value = "copied:")]
+    #[clap(long = "file-copied-label", default_value = "copied:")]
     /// Text to display in front of a copied file path.
     pub file_copied_label: String,
 
-    #[structopt(long = "file-renamed-label", default_value = "renamed:")]
+    #[clap(long = "file-renamed-label", default_value = "renamed:")]
     /// Text to display in front of a renamed file path.
+    ///
+    /// Used in the default value of navigate-regex.
     pub file_renamed_label: String,
 
-    #[structopt(long = "right-arrow", default_value = "⟶  ")]
-    /// Text to display with a changed value such as a diff heading, a rename, or a chmod.
+    #[clap(long = "right-arrow", default_value = "⟶  ")]
+    /// Text to display with a changed file path.
+    ///
+    /// For example, a unified diff heading, a rename, or a chmod.
     pub right_arrow: String,
 
-    #[structopt(long = "hunk-label", default_value = "")]
+    #[clap(long = "hunk-label", default_value = "")]
     /// Text to display in front of a hunk header.
+    ///
+    /// Used in the default value of navigate-regex.
     pub hunk_label: String,
 
-    #[structopt(long = "max-line-length", default_value = "512")]
-    /// Truncate lines longer than this. To prevent any truncation, set to zero. Note that
-    /// delta will be slow on very long lines (e.g. minified .js) if truncation is disabled.
-    /// When wrapping lines it is automatically set to fit at least all visible characters.
+    #[clap(long = "max-line-length", default_value = "512")]
+    /// Truncate lines longer than this.
+    ///
+    /// To prevent any truncation, set to zero. Note that delta will be slow on very long lines
+    /// (e.g. minified .js) if truncation is disabled. When wrapping lines it is automatically set
+    /// to fit at least all visible characters.
     pub max_line_length: usize,
 
-    /// How to extend the background color to the end of the line in side-by-side mode. Can
-    /// be ansi (default) or spaces (default if output is not to a terminal). Has no effect
-    /// if --width=variable is given.
-    #[structopt(long = "line-fill-method")]
+    #[clap(long = "line-fill-method")]
+    /// Line-fill method in side-by-side mode.
+    ///
+    /// How to extend the background color to the end of the line in side-by-side mode. Can be ansi
+    /// (default) or spaces (default if output is not to a terminal). Has no effect if
+    /// --width=variable is given.
     pub line_fill_method: Option<String>,
 
-    /// The width of underline/overline decorations. Examples: "72" (exactly 72 characters),
-    /// "-2" (auto-detected terminal width minus 2). An expression such as "74-2" is also valid
-    /// (equivalent to 72 but may be useful if the caller has a variable holding the value "74").
-    /// Use --width=variable to extend decorations and background colors to the end of the text
-    /// only. Otherwise background colors extend to the full terminal width.
-    #[structopt(short = "w", long = "width")]
+    #[clap(short = 'w', long = "width")]
+    /// The width of underline/overline decorations.
+    ///
+    /// Examples: "72" (exactly 72 characters), "-2" (auto-detected terminal width minus 2). An
+    /// expression such as "74-2" is also valid (equivalent to 72 but may be useful if the caller
+    /// has a variable holding the value "74"). Use --width=variable to extend decorations and
+    /// background colors to the end of the text only. Otherwise background colors extend to the
+    /// full terminal width.
     pub width: Option<String>,
 
-    /// Width allocated for file paths in a diff stat section. If a relativized
-    /// file path exceeds this width then the diff stat will be misaligned.
-    #[structopt(long = "diff-stat-align-width", default_value = "48")]
+    #[clap(long = "diff-stat-align-width", default_value = "48")]
+    /// Width allocated for file paths in a diff stat section.
+    ///
+    /// If a relativized file path exceeds this width then the diff stat will be misaligned.
     pub diff_stat_align_width: usize,
 
-    /// The number of spaces to replace tab characters with. Use --tabs=0 to pass tab characters
-    /// through directly, but note that in that case delta will calculate line widths assuming tabs
-    /// occupy one character's width on the screen: if your terminal renders tabs as more than than
-    /// one character wide then delta's output will look incorrect.
-    #[structopt(long = "tabs", default_value = "4")]
+    #[clap(long = "tabs", default_value = "4")]
+    /// The number of spaces to replace tab characters with.
+    ///
+    /// Use --tabs=0 to pass tab characters through directly, but note that in that case delta will
+    /// calculate line widths assuming tabs occupy one character's width on the screen: if your
+    /// terminal renders tabs as more than than one character wide then delta's output will look
+    /// incorrect.
     pub tab_width: usize,
 
-    /// Whether to emit 24-bit ("true color") RGB color codes. Options are auto, always, and never.
-    /// "auto" means that delta will emit 24-bit color codes if the environment variable COLORTERM
-    /// has the value "truecolor" or "24bit". If your terminal application (the application you use
-    /// to enter commands at a shell prompt) supports 24 bit colors, then it probably already sets
-    /// this environment variable, in which case you don't need to do anything.
-    #[structopt(long = "true-color", default_value = "auto")]
+    #[clap(long = "true-color", default_value = "auto")]
+    /// Whether to emit 24-bit ("true color") RGB color codes.
+    ///
+    /// Options are auto, always, and never. "auto" means that delta will emit 24-bit color codes if
+    /// the environment variable COLORTERM has the value "truecolor" or "24bit". If your terminal
+    /// application (the application you use to enter commands at a shell prompt) supports 24 bit
+    /// colors, then it probably already sets this environment variable, in which case you don't
+    /// need to do anything.
     pub true_color: String,
 
+    #[clap(long = "24-bit-color")]
     /// Deprecated: use --true-color.
-    #[structopt(long = "24-bit-color")]
     pub _24_bit_color: Option<String>,
 
+    #[clap(long = "inspect-raw-lines", default_value = "true")]
+    /// Kill-switch for --color-moved support.
+    ///
     /// Whether to examine ANSI color escape sequences in raw lines received from Git and handle
     /// lines colored in certain ways specially. This is on by default: it is how Delta supports
     /// Git's --color-moved feature. Set this to "false" to disable this behavior.
-    #[structopt(long = "inspect-raw-lines", default_value = "true")]
     pub inspect_raw_lines: String,
 
-    #[structopt(long)]
-    /// Which pager to use. The default pager is `less`. You can also change pager
-    /// by setting the environment variables DELTA_PAGER, BAT_PAGER, or PAGER
-    /// (and that is their order of priority). This option overrides all environment
-    /// variables above.
+    #[clap(long = "pager")]
+    /// Which pager to use.
+    ///
+    /// The default pager is `less`. You can also change pager by setting the environment variables
+    /// DELTA_PAGER, BAT_PAGER, or PAGER (and that is their order of priority). This option
+    /// overrides all environment variables above.
     pub pager: Option<String>,
 
-    /// Whether to use a pager when displaying output. Options are: auto, always, and never.
-    #[structopt(long = "paging", default_value = "auto")]
+    #[clap(long = "paging", default_value = "auto")]
+    /// Whether to use a pager when displaying output.
+    ///
+    /// Options are: auto, always, and never.
     pub paging_mode: String,
 
-    /// First file to be compared when delta is being used in diff mode: `delta file_1 file_2` is
-    /// equivalent to `diff -u file_1 file_2 | delta`.
-    #[structopt(parse(from_os_str))]
+    #[clap(parse(from_os_str))]
+    /// First file to be compared when delta is being used in diff mode
+    ///
+    /// `delta file_1 file_2` is equivalent to `diff -u file_1 file_2 | delta`.
     pub minus_file: Option<PathBuf>,
 
+    #[clap(parse(from_os_str))]
     /// Second file to be compared when delta is being used in diff mode.
-    #[structopt(parse(from_os_str))]
     pub plus_file: Option<PathBuf>,
 
-    /// Style for removed empty line marker (used only if --minus-style has no background color)
-    #[structopt(
+    #[clap(
         long = "--minus-empty-line-marker-style",
         default_value = "normal auto"
     )]
+    /// Style string for removed empty line marker.
+    ///
+    /// Used only if --minus-style has no background color.
     pub minus_empty_line_marker_style: String,
 
-    /// Style for added empty line marker (used only if --plus-style has no background color)
-    #[structopt(long = "--plus-empty-line-marker-style", default_value = "normal auto")]
+    #[clap(long = "--plus-empty-line-marker-style", default_value = "normal auto")]
+    /// Style string for added empty line marker.
+    ///
+    /// Used only if --plus-style has no background color.
     pub plus_empty_line_marker_style: String,
 
-    /// Style for whitespace errors. Defaults to color.diff.whitespace if that is set in git
-    /// config, or else 'magenta reverse'.
-    #[structopt(long = "whitespace-error-style", default_value = "auto auto")]
+    #[clap(long = "whitespace-error-style", default_value = "auto auto")]
+    /// Style string for whitespace errors.
+    ///
+    /// Defaults to color.diff.whitespace if that is set in git config, or else 'magenta reverse'.
     pub whitespace_error_style: String,
 
-    #[structopt(long = "line-buffer-size", default_value = "32")]
-    /// Size of internal line buffer. Delta compares the added and removed versions of nearby lines
-    /// in order to detect and highlight changes at the level of individual words/tokens.
-    /// Therefore, nearby lines must be buffered internally before they are painted and emitted.
-    /// Increasing this value might improve highlighting of some large diff hunks. However, setting
-    /// this to a high value will adversely affect delta's performance when entire files are
-    /// added/removed.
+    #[clap(long = "line-buffer-size", default_value = "32")]
+    /// Size of internal line buffer.
+    ///
+    /// Delta compares the added and removed versions of nearby lines in order to detect and
+    /// highlight changes at the level of individual words/tokens. Therefore, nearby lines must be
+    /// buffered internally before they are painted and emitted. Increasing this value might improve
+    /// highlighting of some large diff hunks. However, setting this to a high value will adversely
+    /// affect delta's performance when entire files are added/removed.
     pub line_buffer_size: usize,
 
-    #[structopt(long = "minus-color")]
+    #[clap(long = "minus-color")]
     /// Deprecated: use --minus-style='normal my_background_color'.
     pub deprecated_minus_background_color: Option<String>,
 
-    #[structopt(long = "minus-emph-color")]
+    #[clap(long = "minus-emph-color")]
     /// Deprecated: use --minus-emph-style='normal my_background_color'.
     pub deprecated_minus_emph_background_color: Option<String>,
 
-    #[structopt(long = "plus-color")]
+    #[clap(long = "plus-color")]
     /// Deprecated: Use --plus-style='syntax my_background_color' to change the background color
     /// while retaining syntax-highlighting.
     pub deprecated_plus_background_color: Option<String>,
 
-    #[structopt(long = "plus-emph-color")]
+    #[clap(long = "plus-emph-color")]
     /// Deprecated: Use --plus-emph-style='syntax my_background_color' to change the background
     /// color while retaining syntax-highlighting.
     pub deprecated_plus_emph_background_color: Option<String>,
 
-    #[structopt(long = "highlight-removed")]
+    #[clap(long = "highlight-removed")]
     /// Deprecated: use --minus-style='syntax'.
     pub deprecated_highlight_minus_lines: bool,
 
-    #[structopt(long = "commit-color")]
+    #[clap(long = "commit-color")]
     /// Deprecated: use --commit-style='my_foreground_color'
     /// --commit-decoration-style='my_foreground_color'.
     pub deprecated_commit_color: Option<String>,
 
-    #[structopt(long = "file-color")]
+    #[clap(long = "file-color")]
     /// Deprecated: use --file-style='my_foreground_color'
     /// --file-decoration-style='my_foreground_color'.
     pub deprecated_file_color: Option<String>,
 
-    #[structopt(long = "hunk-style")]
+    #[clap(long = "hunk-style")]
     /// Deprecated: synonym of --hunk-header-decoration-style.
     pub deprecated_hunk_style: Option<String>,
 
-    #[structopt(long = "hunk-color")]
+    #[clap(long = "hunk-color")]
     /// Deprecated: use --hunk-header-style='my_foreground_color'
     /// --hunk-header-decoration-style='my_foreground_color'.
     pub deprecated_hunk_color: Option<String>,
 
-    #[structopt(long = "theme")]
+    #[clap(long = "theme")]
     /// Deprecated: use --syntax-theme.
     pub deprecated_theme: Option<String>,
 
-    #[structopt(skip)]
+    #[clap(skip)]
     pub computed: ComputedValues,
 
-    #[structopt(skip)]
+    #[clap(skip)]
     pub git_config: Option<GitConfig>,
 
-    #[structopt(skip)]
+    #[clap(skip)]
     pub git_config_entries: HashMap<String, GitConfigEntry>,
 }
 
@@ -882,7 +995,7 @@ impl Opt {
         git_config: Option<GitConfig>,
         assets: HighlightingAssets,
     ) -> Self {
-        Self::from_clap_and_git_config(Self::clap().get_matches(), git_config, assets)
+        Self::from_clap_and_git_config(Self::into_app().get_matches(), git_config, assets)
     }
 
     pub fn from_iter_and_git_config<I>(iter: I, git_config: Option<GitConfig>) -> Self
@@ -891,7 +1004,7 @@ impl Opt {
         I::Item: Into<OsString> + Clone,
     {
         let assets = HighlightingAssets::new();
-        Self::from_clap_and_git_config(Self::clap().get_matches_from(iter), git_config, assets)
+        Self::from_clap_and_git_config(Self::into_app().get_matches_from(iter), git_config, assets)
     }
 
     fn from_clap_and_git_config(
@@ -899,28 +1012,29 @@ impl Opt {
         mut git_config: Option<GitConfig>,
         assets: HighlightingAssets,
     ) -> Self {
-        let mut opt = Opt::from_clap(&arg_matches);
+        let mut opt = Opt::from_arg_matches(&arg_matches)
+            .unwrap_or_else(|_| delta_unreachable("Opt::from_arg_matches failed"));
         options::rewrite::apply_rewrite_rules(&mut opt, &arg_matches);
         options::set::set_options(&mut opt, &mut git_config, &arg_matches, assets);
         opt.git_config = git_config;
         opt
     }
 
-    #[allow(dead_code)]
-    pub fn get_option_names<'a>() -> HashMap<&'a str, &'a str> {
+    pub fn get_argument_and_option_names<'a>() -> HashMap<&'a str, &'a str> {
         itertools::chain(
-            Self::clap()
-                .p
-                .opts
-                .iter()
-                .map(|opt| (opt.b.name, opt.s.long.unwrap())),
-            Self::clap()
-                .p
-                .flags
-                .iter()
-                .map(|opt| (opt.b.name, opt.s.long.unwrap())),
+            Self::into_app().get_opts(),
+            Self::into_app().get_arguments(),
         )
-        .filter(|(name, _)| !IGNORED_OPTION_NAMES.contains(name))
+        .filter_map(|arg| match (arg.get_name(), arg.get_long()) {
+            (name, Some(long)) => {
+                if IGNORED_OPTION_NAMES.contains(name) {
+                    None
+                } else {
+                    Some((name, long))
+                }
+            }
+            _ => None,
+        })
         .collect()
     }
 }