Fix Clippy lints

Also remove `allow(clippy::*)`s where possible

src/book/mod.rs

@@ -386,7 +386,7 @@ fn determine_renderers(config: &Config) -> Vec<Box<dyn Renderer>> {
     renderers
 }
 
-const DEFAULT_PREPROCESSORS: &[&'static str] = &["links", "index"];
+const DEFAULT_PREPROCESSORS: &[&str] = &["links", "index"];
 
 fn is_default_preprocessor(pre: &dyn Preprocessor) -> bool {
     let name = pre.name();
@@ -756,10 +756,9 @@ mod tests {
 
         let preprocessors = determine_preprocessors(&cfg).unwrap();
 
-        assert!(preprocessors
+        assert!(!preprocessors
             .iter()
-            .find(|preprocessor| preprocessor.name() == "random")
-            .is_none());
+            .any(|preprocessor| preprocessor.name() == "random"));
     }
 
     #[test]
@@ -776,10 +775,9 @@ mod tests {
 
         let preprocessors = determine_preprocessors(&cfg).unwrap();
 
-        assert!(preprocessors
+        assert!(!preprocessors
             .iter()
-            .find(|preprocessor| preprocessor.name() == "links")
-            .is_none());
+            .any(|preprocessor| preprocessor.name() == "links"));
     }
 
     #[test]

src/cmd/init.rs

@@ -122,8 +122,5 @@ fn confirm() -> bool {
     io::stdout().flush().unwrap();
     let mut s = String::new();
     io::stdin().read_line(&mut s).ok();
-    match &*s.trim() {
-        "Y" | "y" | "yes" | "Yes" => true,
-        _ => false,
-    }
+    matches!(&*s.trim(), "Y" | "y" | "yes" | "Yes")
 }

src/config.rs

@@ -227,10 +227,10 @@ impl Config {
         let value = Value::try_from(value)
             .with_context(|| "Unable to represent the item as a JSON Value")?;
 
-        if index.starts_with("book.") {
-            self.book.update_value(&index[5..], value);
-        } else if index.starts_with("build.") {
-            self.build.update_value(&index[6..], value);
+        if let Some(key) = index.strip_prefix("book.") {
+            self.book.update_value(key, value);
+        } else if let Some(key) = index.strip_prefix("build.") {
+            self.build.update_value(key, value);
         } else {
             self.rest.insert(index, value);
         }
@@ -371,15 +371,8 @@ impl Serialize for Config {
 }
 
 fn parse_env(key: &str) -> Option<String> {
-    const PREFIX: &str = "MDBOOK_";
-
-    if key.starts_with(PREFIX) {
-        let key = &key[PREFIX.len()..];
-
-        Some(key.to_lowercase().replace("__", ".").replace("_", "-"))
-    } else {
-        None
-    }
+    key.strip_prefix("MDBOOK_")
+        .map(|key| key.to_lowercase().replace("__", ".").replace('_', "-"))
 }
 
 fn is_legacy_format(table: &Value) -> bool {
@@ -828,7 +821,7 @@ mod tests {
         "#;
 
         let got = Config::from_str(src).unwrap();
-        assert_eq!(got.html_config().unwrap().playground.runnable, false);
+        assert!(!got.html_config().unwrap().playground.runnable);
     }
 
     #[test]
@@ -1037,7 +1030,7 @@ mod tests {
     fn encode_env_var(key: &str) -> String {
         format!(
             "MDBOOK_{}",
-            key.to_uppercase().replace('.', "__").replace("-", "_")
+            key.to_uppercase().replace('.', "__").replace('-', "_")
         )
     }
 
@@ -1061,11 +1054,10 @@ mod tests {
     }
 
     #[test]
-    #[allow(clippy::approx_constant)]
     fn update_config_using_env_var_and_complex_value() {
         let mut cfg = Config::default();
         let key = "foo-bar.baz";
-        let value = json!({"array": [1, 2, 3], "number": 3.14});
+        let value = json!({"array": [1, 2, 3], "number": 13.37});
         let value_str = serde_json::to_string(&value).unwrap();
 
         assert!(cfg.get(key).is_none());
@@ -1184,15 +1176,15 @@ mod tests {
         "#;
         let got = Config::from_str(src).unwrap();
         let html_config = got.html_config().unwrap();
-        assert_eq!(html_config.print.enable, false);
-        assert_eq!(html_config.print.page_break, true);
+        assert!(!html_config.print.enable);
+        assert!(html_config.print.page_break);
         let src = r#"
         [output.html.print]
         page-break = false
         "#;
         let got = Config::from_str(src).unwrap();
         let html_config = got.html_config().unwrap();
-        assert_eq!(html_config.print.enable, true);
-        assert_eq!(html_config.print.page_break, false);
+        assert!(html_config.print.enable);
+        assert!(!html_config.print.page_break);
     }
 }

src/lib.rs

@@ -82,7 +82,6 @@
 
 #![deny(missing_docs)]
 #![deny(rust_2018_idioms)]
-#![allow(clippy::comparison_chain)]
 
 #[macro_use]
 extern crate lazy_static;

src/preprocess/links.rs

@@ -146,6 +146,7 @@ enum RangeOrAnchor {
 }
 
 // A range of lines specified with some include directive.
+#[allow(clippy::enum_variant_names)] // The prefix can't be removed, and is meant to mirror the contained type
 #[derive(PartialEq, Debug, Clone)]
 enum LineRange {
     Range(Range<usize>),

src/renderer/html_handlebars/hbs_renderer.rs

@@ -814,7 +814,7 @@ fn fix_code_blocks(html: &str) -> String {
     FIX_CODE_BLOCKS
         .replace_all(html, |caps: &Captures<'_>| {
             let before = &caps[1];
-            let classes = &caps[2].replace(",", " ");
+            let classes = &caps[2].replace(',', " ");
             let after = &caps[3];
 
             format!(

src/renderer/html_handlebars/helpers/navigation.rs

@@ -61,7 +61,7 @@ fn find_chapter(
         .as_json()
         .as_str()
         .ok_or_else(|| RenderError::new("Type error for `path`, string expected"))?
-        .replace("\"", "");
+        .replace('\"', "");
 
     if !rc.evaluate(ctx, "@root/is_index")?.is_missing() {
         // Special case for index.md which may be a synthetic page.
@@ -121,7 +121,7 @@ fn render(
         .as_json()
         .as_str()
         .ok_or_else(|| RenderError::new("Type error for `path`, string expected"))?
-        .replace("\"", "");
+        .replace('\"', "");
 
     context.insert(
         "path_to_root".to_owned(),
@@ -141,7 +141,7 @@ fn render(
                 .with_extension("html")
                 .to_str()
                 .ok_or_else(|| RenderError::new("Link could not be converted to str"))
-                .map(|p| context.insert("link".to_owned(), json!(p.replace("\\", "/"))))
+                .map(|p| context.insert("link".to_owned(), json!(p.replace('\\', "/"))))
         })?;
 
     trace!("Render template");

src/renderer/html_handlebars/helpers/toc.rs

@@ -1,5 +1,5 @@
-use std::collections::BTreeMap;
 use std::path::Path;
+use std::{cmp::Ordering, collections::BTreeMap};
 
 use crate::utils;
 use crate::utils::bracket_escape;
@@ -33,7 +33,7 @@ impl HelperDef for RenderToc {
             .as_json()
             .as_str()
             .ok_or_else(|| RenderError::new("Type error for `path`, string expected"))?
-            .replace("\"", "");
+            .replace('\"', "");
 
         let current_section = rc
             .evaluate(ctx, "@root/section")?
@@ -81,22 +81,26 @@ impl HelperDef for RenderToc {
                     level - 1 < fold_level as usize
                 };
 
-            if level > current_level {
-                while level > current_level {
-                    out.write("<li>")?;
-                    out.write("<ol class=\"section\">")?;
-                    current_level += 1;
+            match level.cmp(&current_level) {
+                Ordering::Greater => {
+                    while level > current_level {
+                        out.write("<li>")?;
+                        out.write("<ol class=\"section\">")?;
+                        current_level += 1;
+                    }
+                    write_li_open_tag(out, is_expanded, false)?;
                 }
-                write_li_open_tag(out, is_expanded, false)?;
-            } else if level < current_level {
-                while level < current_level {
-                    out.write("</ol>")?;
-                    out.write("</li>")?;
-                    current_level -= 1;
+                Ordering::Less => {
+                    while level < current_level {
+                        out.write("</ol>")?;
+                        out.write("</li>")?;
+                        current_level -= 1;
+                    }
+                    write_li_open_tag(out, is_expanded, false)?;
+                }
+                Ordering::Equal => {
+                    write_li_open_tag(out, is_expanded, item.get("section").is_none())?;
                 }
-                write_li_open_tag(out, is_expanded, false)?;
-            } else {
-                write_li_open_tag(out, is_expanded, item.get("section").is_none())?;
             }
 
             // Part title
@@ -119,7 +123,7 @@ impl HelperDef for RenderToc {
                     .to_str()
                     .unwrap()
                     // Hack for windows who tends to use `\` as separator instead of `/`
-                    .replace("\\", "/");
+                    .replace('\\', "/");
 
                 // Add link
                 out.write(&utils::fs::path_to_root(&current_path))?;

src/renderer/html_handlebars/search.rs

@@ -211,12 +211,13 @@ fn write_to_json(index: Index, search_config: &Search, doc_urls: Vec<String>) ->
 
     let mut fields = BTreeMap::new();
     let mut opt = SearchOptionsField::default();
-    opt.boost = Some(search_config.boost_title);
-    fields.insert("title".into(), opt);
-    opt.boost = Some(search_config.boost_paragraph);
-    fields.insert("body".into(), opt);
-    opt.boost = Some(search_config.boost_hierarchy);
-    fields.insert("breadcrumbs".into(), opt);
+    let mut insert_boost = |key: &str, boost| {
+        opt.boost = Some(boost);
+        fields.insert(key.into(), opt);
+    };
+    insert_boost("title", search_config.boost_title);
+    insert_boost("body", search_config.boost_paragraph);
+    insert_boost("breadcrumbs", search_config.boost_hierarchy);
 
     let search_options = SearchOptions {
         bool: if search_config.use_boolean_and {

src/utils/string.rs

@@ -122,6 +122,7 @@ mod tests {
     };
 
     #[test]
+    #[allow(clippy::reversed_empty_ranges)] // Intentionally checking that those are correctly handled
     fn take_lines_test() {
         let s = "Lorem\nipsum\ndolor\nsit\namet";
         assert_eq!(take_lines(s, 1..3), "ipsum\ndolor");
@@ -163,6 +164,7 @@ mod tests {
     }
 
     #[test]
+    #[allow(clippy::reversed_empty_ranges)] // Intentionally checking that those are correctly handled
     fn take_rustdoc_include_lines_test() {
         let s = "Lorem\nipsum\ndolor\nsit\namet";
         assert_eq!(