refactor: fix clippy warnings (#165)

Author: Sven

src/filter/mod.rs

@@ -312,7 +312,7 @@ fn parse_spec(spec: &str) -> (Vec<Directive>, Option<inner::Filter>) {
     }
     mods.map(|m| {
         for s in m.split(',') {
-            if s.len() == 0 {
+            if s.is_empty() {
                 continue;
             }
             let mut parts = s.split('=');
@@ -354,15 +354,15 @@ fn parse_spec(spec: &str) -> (Vec<Directive>, Option<inner::Filter>) {
         }
     });
 
-    let filter = filter.map_or(None, |filter| match inner::Filter::new(filter) {
+    let filter = filter.and_then(|filter| match inner::Filter::new(filter) {
         Ok(re) => Some(re),
         Err(e) => {
             eprintln!("warning: invalid regex filter - {}", e);
             None
         }
     });
 
-    return (dirs, filter);
+    (dirs, filter)
 }
 
 // Check whether a level and target are enabled by the set of directives.

src/fmt/writer/atty.rs

@@ -9,8 +9,6 @@ from being printed.
 
 #[cfg(feature = "atty")]
 mod imp {
-    use atty;
-
     pub(in crate::fmt) fn is_stdout() -> bool {
         atty::is(atty::Stream::Stdout)
     }

src/lib.rs

@@ -245,6 +245,7 @@
 #![cfg_attr(rustbuild, feature(staged_api, rustc_private))]
 #![cfg_attr(rustbuild, unstable(feature = "rustc_private", issue = "27812"))]
 #![deny(missing_debug_implementations, missing_docs, warnings)]
+#![allow(clippy::needless_doctest_main)]
 
 use std::{borrow::Cow, cell::RefCell, env, io};
 
@@ -260,10 +261,10 @@ use self::fmt::writer::{self, Writer};
 use self::fmt::Formatter;
 
 /// The default name for the environment variable to read filters from.
-pub const DEFAULT_FILTER_ENV: &'static str = "RUST_LOG";
+pub const DEFAULT_FILTER_ENV: &str = "RUST_LOG";
 
 /// The default name for the environment variable to read style preferences from.
-pub const DEFAULT_WRITE_STYLE_ENV: &'static str = "RUST_LOG_STYLE";
+pub const DEFAULT_WRITE_STYLE_ENV: &str = "RUST_LOG_STYLE";
 
 /// Set of environment variables to configure from.
 ///