diff --git a/src/tools/tidy/src/cargo.rs b/src/tools/tidy/src/cargo.rs
index f40fea60f40a8..69f61bc248dbb 100644
--- a/src/tools/tidy/src/cargo.rs
+++ b/src/tools/tidy/src/cargo.rs
@@ -65,9 +65,8 @@ fn verify(tomlfile: &Path, libfile: &Path, bad: &mut bool) {
         Some(i) => &toml[i+1..],
         None => return,
     };
-    let mut lines = deps.lines().peekable();
-    while let Some(line) = lines.next() {
-        if line.starts_with("[") {
+    for line in deps.lines() {
+        if line.starts_with('[') {
             break
         }
 
diff --git a/src/tools/tidy/src/deps.rs b/src/tools/tidy/src/deps.rs
index 68a4b7898575d..7278bbf3595c8 100644
--- a/src/tools/tidy/src/deps.rs
+++ b/src/tools/tidy/src/deps.rs
@@ -18,7 +18,7 @@ use std::process::Command;
 
 use serde_json;
 
-static LICENSES: &'static [&'static str] = &[
+const LICENSES: &[&str] = &[
     "MIT/Apache-2.0",
     "MIT / Apache-2.0",
     "Apache-2.0/MIT",
@@ -33,7 +33,7 @@ static LICENSES: &'static [&'static str] = &[
 /// should be considered bugs. Exceptions are only allowed in Rust
 /// tooling. It is _crucial_ that no exception crates be dependencies
 /// of the Rust runtime (std / test).
-static EXCEPTIONS: &'static [&'static str] = &[
+const EXCEPTIONS: &[&str] = &[
     "mdbook",             // MPL2, mdbook
     "openssl",            // BSD+advertising clause, cargo, mdbook
     "pest",               // MPL2, mdbook via handlebars
@@ -54,13 +54,13 @@ static EXCEPTIONS: &'static [&'static str] = &[
 ];
 
 /// Which crates to check against the whitelist?
-static WHITELIST_CRATES: &'static [CrateVersion] = &[
+const WHITELIST_CRATES: &[CrateVersion] = &[
     CrateVersion("rustc", "0.0.0"),
     CrateVersion("rustc_codegen_llvm", "0.0.0"),
 ];
 
 /// Whitelist of crates rustc is allowed to depend on. Avoid adding to the list if possible.
-static WHITELIST: &'static [Crate] = &[
+const WHITELIST: &[Crate] = &[
     Crate("aho-corasick"),
     Crate("arrayvec"),
     Crate("atty"),
@@ -205,12 +205,13 @@ pub fn check(path: &Path, bad: &mut bool) {
         let dir = t!(dir);
 
         // skip our exceptions
-        if EXCEPTIONS.iter().any(|exception| {
+        let is_exception = EXCEPTIONS.iter().any(|exception| {
             dir.path()
                 .to_str()
                 .unwrap()
                 .contains(&format!("src/vendor/{}", exception))
-        }) {
+        });
+        if is_exception {
             continue;
         }
 
@@ -239,7 +240,7 @@ pub fn check_whitelist(path: &Path, cargo: &Path, bad: &mut bool) {
         unapproved.append(&mut bad);
     }
 
-    if unapproved.len() > 0 {
+    if !unapproved.is_empty() {
         println!("Dependencies not on the whitelist:");
         for dep in unapproved {
             println!("* {}", dep.id_str());
diff --git a/src/tools/tidy/src/errors.rs b/src/tools/tidy/src/errors.rs
index 3dccffddf9388..9f55d6f9ad636 100644
--- a/src/tools/tidy/src/errors.rs
+++ b/src/tools/tidy/src/errors.rs
@@ -50,7 +50,7 @@ pub fn check(path: &Path, bad: &mut bool) {
             }
 
             let mut search = line;
-            while let Some(i) = search.find("E") {
+            while let Some(i) = search.find('E') {
                 search = &search[i + 1..];
                 let code = if search.len() > 4 {
                     search[..4].parse::<u32>()
diff --git a/src/tools/tidy/src/extdeps.rs b/src/tools/tidy/src/extdeps.rs
index 761803a45b8b3..7f58b440a833e 100644
--- a/src/tools/tidy/src/extdeps.rs
+++ b/src/tools/tidy/src/extdeps.rs
@@ -15,7 +15,7 @@ use std::io::Read;
 use std::path::Path;
 
 /// List of whitelisted sources for packages
-static WHITELISTED_SOURCES: &'static [&'static str] = &[
+const WHITELISTED_SOURCES: &[&str] = &[
     "\"registry+https://github.com/rust-lang/crates.io-index\"",
 ];
 
@@ -29,8 +29,7 @@ pub fn check(path: &Path, bad: &mut bool) {
     t!(t!(File::open(path)).read_to_string(&mut cargo_lock));
 
     // process each line
-    let mut lines = cargo_lock.lines();
-    while let Some(line) = lines.next() {
+    for line in cargo_lock.lines() {
 
         // consider only source entries
         if ! line.starts_with("source = ") {
@@ -38,8 +37,7 @@ pub fn check(path: &Path, bad: &mut bool) {
         }
 
         // extract source value
-        let parts: Vec<&str> = line.splitn(2, "=").collect();
-        let source = parts[1].trim();
+        let source = line.splitn(2, '=').nth(1).unwrap().trim();
 
         // ensure source is whitelisted
         if !WHITELISTED_SOURCES.contains(&&*source) {
diff --git a/src/tools/tidy/src/features.rs b/src/tools/tidy/src/features.rs
index 74f66c0a05169..85b123e4af51f 100644
--- a/src/tools/tidy/src/features.rs
+++ b/src/tools/tidy/src/features.rs
@@ -75,7 +75,7 @@ pub fn check(path: &Path, bad: &mut bool, quiet: bool) {
             return;
         }
 
-        let filen_underscore = filename.replace("-","_").replace(".rs","");
+        let filen_underscore = filename.replace('-',"_").replace(".rs","");
         let filename_is_gate_test = test_filen_gate(&filen_underscore, &mut features);
 
         contents.truncate(0);
@@ -88,13 +88,9 @@ pub fn check(path: &Path, bad: &mut bool, quiet: bool) {
 
             let gate_test_str = "gate-test-";
 
-            if !line.contains(gate_test_str) {
-                continue;
-            }
-
             let feature_name = match line.find(gate_test_str) {
                 Some(i) => {
-                    &line[i+gate_test_str.len()..line[i+1..].find(' ').unwrap_or(line.len())]
+                    line[i+gate_test_str.len()..].splitn(2, ' ').next().unwrap()
                 },
                 None => continue,
             };
@@ -133,7 +129,7 @@ pub fn check(path: &Path, bad: &mut bool, quiet: bool) {
                  name);
     }
 
-    if gate_untested.len() > 0 {
+    if !gate_untested.is_empty() {
         tidy_error!(bad, "Found {} features without a gate test.", gate_untested.len());
     }
 
@@ -259,14 +255,11 @@ pub fn collect_lib_features(base_src_path: &Path) -> Features {
 
     map_lib_features(base_src_path,
                      &mut |res, _, _| {
-        match res {
-            Ok((name, feature)) => {
-                if lib_features.get(name).is_some() {
-                    return;
-                }
-                lib_features.insert(name.to_owned(), feature);
-            },
-            Err(_) => (),
+        if let Ok((name, feature)) = res {
+            if lib_features.contains_key(name) {
+                return;
+            }
+            lib_features.insert(name.to_owned(), feature);
         }
     });
    lib_features
@@ -332,11 +325,11 @@ fn map_lib_features(base_src_path: &Path,
                     f.tracking_issue = find_attr_val(line, "issue")
                     .map(|s| s.parse().unwrap());
                 }
-                if line.ends_with("]") {
+                if line.ends_with(']') {
                     mf(Ok((name, f.clone())), file, i + 1);
-                } else if !line.ends_with(",") && !line.ends_with("\\") {
+                } else if !line.ends_with(',') && !line.ends_with('\\') {
                     // We need to bail here because we might have missed the
-                    // end of a stability attribute above because the "]"
+                    // end of a stability attribute above because the ']'
                     // might not have been at the end of the line.
                     // We could then get into the very unfortunate situation that
                     // we continue parsing the file assuming the current stability
@@ -394,7 +387,7 @@ fn map_lib_features(base_src_path: &Path,
                 has_gate_test: false,
                 tracking_issue,
             };
-            if line.contains("]") {
+            if line.contains(']') {
                 mf(Ok((feature_name, feature)), file, i + 1);
             } else {
                 becoming_feature = Some((feature_name.to_owned(), feature));
diff --git a/src/tools/tidy/src/main.rs b/src/tools/tidy/src/main.rs
index 4fe77f8b58feb..22fa954e5fa55 100644
--- a/src/tools/tidy/src/main.rs
+++ b/src/tools/tidy/src/main.rs
@@ -24,11 +24,8 @@ use std::path::PathBuf;
 use std::env;
 
 fn main() {
-    let path = env::args_os().skip(1).next().expect("need path to src");
-    let path = PathBuf::from(path);
-
-    let cargo = env::args_os().skip(2).next().expect("need path to cargo");
-    let cargo = PathBuf::from(cargo);
+    let path: PathBuf = env::args_os().nth(1).expect("need path to src").into();
+    let cargo: PathBuf = env::args_os().nth(2).expect("need path to cargo").into();
 
     let args: Vec<String> = env::args().skip(1).collect();
 
diff --git a/src/tools/tidy/src/pal.rs b/src/tools/tidy/src/pal.rs
index 8071f07d81195..69a4c09c2285d 100644
--- a/src/tools/tidy/src/pal.rs
+++ b/src/tools/tidy/src/pal.rs
@@ -50,7 +50,7 @@ use std::path::Path;
 use std::iter::Iterator;
 
 // Paths that may contain platform-specific code
-const EXCEPTION_PATHS: &'static [&'static str] = &[
+const EXCEPTION_PATHS: &[&str] = &[
     // std crates
     "src/liballoc_jemalloc",
     "src/liballoc_system",
@@ -88,10 +88,10 @@ const EXCEPTION_PATHS: &'static [&'static str] = &[
 ];
 
 pub fn check(path: &Path, bad: &mut bool) {
-    let ref mut contents = String::new();
+    let mut contents = String::new();
     // Sanity check that the complex parsing here works
-    let ref mut saw_target_arch = false;
-    let ref mut saw_cfg_bang = false;
+    let mut saw_target_arch = false;
+    let mut saw_cfg_bang = false;
     super::walk(path, &mut super::filter_dirs, &mut |file| {
         let filestr = file.to_string_lossy().replace("\\", "/");
         if !filestr.ends_with(".rs") { return }
@@ -99,11 +99,11 @@ pub fn check(path: &Path, bad: &mut bool) {
         let is_exception_path = EXCEPTION_PATHS.iter().any(|s| filestr.contains(&**s));
         if is_exception_path { return }
 
-        check_cfgs(contents, &file, bad, saw_target_arch, saw_cfg_bang);
+        check_cfgs(&mut contents, &file, bad, &mut saw_target_arch, &mut saw_cfg_bang);
     });
 
-    assert!(*saw_target_arch);
-    assert!(*saw_cfg_bang);
+    assert!(saw_target_arch);
+    assert!(saw_cfg_bang);
 }
 
 fn check_cfgs(contents: &mut String, file: &Path,
@@ -130,7 +130,7 @@ fn check_cfgs(contents: &mut String, file: &Path,
         tidy_error!(bad, "{}:{}: platform-specific cfg: {}", file.display(), line, cfg);
     };
 
-    for (idx, cfg) in cfgs.into_iter() {
+    for (idx, cfg) in cfgs {
         // Sanity check that the parsing here works
         if !*saw_target_arch && cfg.contains("target_arch") { *saw_target_arch = true }
         if !*saw_cfg_bang && cfg.contains("cfg!") { *saw_cfg_bang = true }
@@ -216,7 +216,7 @@ fn parse_cfgs<'a>(contents: &'a str) -> Vec<(usize, &'a str)> {
                 b')' => {
                     depth -= 1;
                     if depth == 0 {
-                        return (i, &contents_from[.. j + 1]);
+                        return (i, &contents_from[..=j]);
                     }
                 }
                 _ => { }
diff --git a/src/tools/tidy/src/style.rs b/src/tools/tidy/src/style.rs
index 6b431ccda0883..33cd8b5dcd9ab 100644
--- a/src/tools/tidy/src/style.rs
+++ b/src/tools/tidy/src/style.rs
@@ -69,7 +69,7 @@ fn line_is_url(line: &str) -> bool {
             (EXP_COMMENT_START, "//!") => state = EXP_LINK_LABEL_OR_URL,
 
             (EXP_LINK_LABEL_OR_URL, w)
-                if w.len() >= 4 && w.starts_with("[") && w.ends_with("]:")
+                if w.len() >= 4 && w.starts_with('[') && w.ends_with("]:")
                 => state = EXP_URL,
 
             (EXP_LINK_LABEL_OR_URL, w)
@@ -128,13 +128,13 @@ pub fn check(path: &Path, bad: &mut bool) {
                 && !long_line_is_ok(line) {
                     err(&format!("line longer than {} chars", COLS));
             }
-            if line.contains("\t") && !skip_tab {
+            if line.contains('\t') && !skip_tab {
                 err("tab character");
             }
-            if !skip_end_whitespace && (line.ends_with(" ") || line.ends_with("\t")) {
+            if !skip_end_whitespace && (line.ends_with(' ') || line.ends_with('\t')) {
                 err("trailing whitespace");
             }
-            if line.contains("\r") && !skip_cr {
+            if line.contains('\r') && !skip_cr {
                 err("CR character");
             }
             if filename != "style.rs" {
diff --git a/src/tools/tidy/src/unstable_book.rs b/src/tools/tidy/src/unstable_book.rs
index 62296f73f016b..520879df620ee 100644
--- a/src/tools/tidy/src/unstable_book.rs
+++ b/src/tools/tidy/src/unstable_book.rs
@@ -56,12 +56,11 @@ pub fn collect_unstable_feature_names(features: &Features) -> BTreeSet<String> {
 pub fn collect_unstable_book_section_file_names(dir: &path::Path) -> BTreeSet<String> {
     fs::read_dir(dir)
         .expect("could not read directory")
-        .into_iter()
         .map(|entry| entry.expect("could not read directory entry"))
         .filter(dir_entry_is_file)
-        .map(|entry| entry.file_name().into_string().unwrap())
-        .filter(|n| n.ends_with(".md"))
-        .map(|n| n.trim_right_matches(".md").to_owned())
+        .map(|entry| entry.path())
+        .filter(|path| path.extension().map(|e| e.to_str().unwrap()) == Some("md"))
+        .map(|path| path.file_stem().unwrap().to_str().unwrap().into())
         .collect()
 }