Fix most of clippy warnings (#914)

* Fix clippy: cast_lossless

* Fix clippy: match_ref_pats

* Fix clippy: extra_unused_lifetimes

* Fix clippy: needless_lifetimes

* Fix clippy: new_without_default

* Fix clippy: or_fun_call

* Fix clippy: should_implement_trait

* Fix clippy: redundant_closure

* Fix clippy: const_static_lifetime

* Fix clippy: redundant_pattern_matching

* Fix clippy: unused_io_amount

* Fix clippy: string_lit_as_bytes

* Fix clippy: needless_update

* Fix clippy: blacklisted_name

* Fix clippy: collapsible_if

* Fix clippy: match_wild_err_arm

* Fix clippy: single_match

* Fix clippy: useless_vec

* Fix clippy: single_char_pattern

* Fix clippy: float_cmp

* Fix clippy: approx_constant

2 files changed, 15 insertions, 13 deletions

diff --git a/src/book/book.rs b/src/book/book.rs
index 62af2d92..c98c03c2 100644
--- a/src/book/book.rs
+++ b/src/book/book.rs
@@ -116,7 +116,7 @@ where
     I: IntoIterator<Item = &'a mut BookItem>,
 {
     for item in items {
-        if let &mut BookItem::Chapter(ref mut ch) = item {
+        if let BookItem::Chapter(ch) = item {
             for_each_mut(func, &mut ch.sub_items);
         }
 
@@ -301,7 +301,7 @@ mod tests {
     use std::io::Write;
     use tempfile::{Builder as TempFileBuilder, TempDir};
 
-    const DUMMY_SRC: &'static str = "
+    const DUMMY_SRC: &str = "
 # Dummy Chapter
 
 this is some dummy text.
@@ -317,7 +317,7 @@ And here is some \
         let chapter_path = temp.path().join("chapter_1.md");
         File::create(&chapter_path)
             .unwrap()
-            .write(DUMMY_SRC.as_bytes())
+            .write_all(DUMMY_SRC.as_bytes())
             .unwrap();
 
         let link = Link::new("Chapter 1", chapter_path);
@@ -333,7 +333,7 @@ And here is some \
 
         File::create(&second_path)
             .unwrap()
-            .write_all("Hello World!".as_bytes())
+            .write_all(b"Hello World!")
             .unwrap();
 
         let mut second = Link::new("Nested Chapter 1", &second_path);
diff --git a/src/book/mod.rs b/src/book/mod.rs
index 5002c353..41ae50d9 100644
--- a/src/book/mod.rs
+++ b/src/book/mod.rs
@@ -16,6 +16,7 @@ pub use self::summary::{parse_summary, Link, SectionNumber, Summary, SummaryItem
 use std::io::Write;
 use std::path::PathBuf;
 use std::process::Command;
+use std::string::ToString;
 use tempfile::Builder as TempFileBuilder;
 use toml::Value;
 
@@ -346,7 +347,7 @@ impl MDBook {
 fn determine_renderers(config: &Config) -> Vec<Box<Renderer>> {
     let mut renderers: Vec<Box<Renderer>> = Vec::new();
 
-    if let Some(output_table) = config.get("output").and_then(|o| o.as_table()) {
+    if let Some(output_table) = config.get("output").and_then(Value::as_table) {
         for (key, table) in output_table.iter() {
             // the "html" backend has its own Renderer
             if key == "html" {
@@ -386,7 +387,7 @@ fn determine_preprocessors(config: &Config) -> Result<Vec<Box<Preprocessor>>> {
         preprocessors.extend(default_preprocessors());
     }
 
-    if let Some(preprocessor_table) = config.get("preprocessor").and_then(|v| v.as_table()) {
+    if let Some(preprocessor_table) = config.get("preprocessor").and_then(Value::as_table) {
         for key in preprocessor_table.keys() {
             match key.as_ref() {
                 "links" => preprocessors.push(Box::new(LinkPreprocessor::new())),
@@ -405,8 +406,8 @@ fn determine_preprocessors(config: &Config) -> Result<Vec<Box<Preprocessor>>> {
 fn interpret_custom_preprocessor(key: &str, table: &Value) -> Box<CmdPreprocessor> {
     let command = table
         .get("command")
-        .and_then(|c| c.as_str())
-        .map(|s| s.to_string())
+        .and_then(Value::as_str)
+        .map(ToString::to_string)
         .unwrap_or_else(|| format!("mdbook-{}", key));
 
     Box::new(CmdPreprocessor::new(key.to_string(), command.to_string()))
@@ -417,8 +418,8 @@ fn interpret_custom_renderer(key: &str, table: &Value) -> Box<CmdRenderer> {
     // prepended by "mdbook-"
     let table_dot_command = table
         .get("command")
-        .and_then(|c| c.as_str())
-        .map(|s| s.to_string());
+        .and_then(Value::as_str)
+        .map(ToString::to_string);
 
     let command = table_dot_command.unwrap_or_else(|| format!("mdbook-{}", key));
 
@@ -443,7 +444,7 @@ fn preprocessor_should_run(preprocessor: &Preprocessor, renderer: &Renderer, cfg
     if let Some(Value::Array(ref explicit_renderers)) = cfg.get(&key) {
         return explicit_renderers
             .iter()
-            .filter_map(|val| val.as_str())
+            .filter_map(Value::as_str)
             .any(|name| name == renderer_name);
     }
 
@@ -453,6 +454,7 @@ fn preprocessor_should_run(preprocessor: &Preprocessor, renderer: &Renderer, cfg
 #[cfg(test)]
 mod tests {
     use super::*;
+    use std::str::FromStr;
     use toml::value::{Table, Value};
 
     #[test]
@@ -570,9 +572,9 @@ mod tests {
         let html = cfg
             .get_preprocessor("links")
             .and_then(|links| links.get("renderers"))
-            .and_then(|renderers| renderers.as_array())
+            .and_then(Value::as_array)
             .and_then(|renderers| renderers.get(0))
-            .and_then(|renderer| renderer.as_str())
+            .and_then(Value::as_str)
             .unwrap();
         assert_eq!(html, "html");
         let html_renderer = HtmlHandlebars::default();