diff --git a/crates/cargo-test-support/src/lib.rs b/crates/cargo-test-support/src/lib.rs
index 0ee88e8d4b4..d43bc96d498 100644
--- a/crates/cargo-test-support/src/lib.rs
+++ b/crates/cargo-test-support/src/lib.rs
@@ -1158,9 +1158,7 @@ impl Execs {
 
         // It's easier to read tabs in outputs if they don't show up as literal
         // hidden characters
-        let matcher = matcher.replace("\t", "<tab>");
-
-        matcher
+        matcher.replace("\t", "<tab>")
     }
 
     fn match_std(
diff --git a/src/cargo/core/compiler/context/compilation_files.rs b/src/cargo/core/compiler/context/compilation_files.rs
index 743d7d821c5..0178034e3ee 100644
--- a/src/cargo/core/compiler/context/compilation_files.rs
+++ b/src/cargo/core/compiler/context/compilation_files.rs
@@ -372,9 +372,9 @@ impl<'a, 'cfg: 'a> CompilationFiles<'a, 'cfg> {
                             None
                         } else {
                             self.export_dir.as_ref().and_then(|export_dir| {
-                                hardlink.as_ref().and_then(|hardlink| {
-                                    Some(export_dir.join(hardlink.file_name().unwrap()))
-                                })
+                                hardlink
+                                    .as_ref()
+                                    .map(|hardlink| export_dir.join(hardlink.file_name().unwrap()))
                             })
                         };
                         ret.push(OutputFile {
diff --git a/src/cargo/core/compiler/custom_build.rs b/src/cargo/core/compiler/custom_build.rs
index f727087ccfa..e5f7157dc4c 100644
--- a/src/cargo/core/compiler/custom_build.rs
+++ b/src/cargo/core/compiler/custom_build.rs
@@ -518,7 +518,7 @@ impl BuildOutput {
                 // common with tools like pkg-config
                 // e.g. -L/some/dir/local/lib or -licui18n
                 let (flag, mut value) = flag.split_at(2);
-                if value.len() == 0 {
+                if value.is_empty() {
                     value = match flags_iter.next() {
                         Some(v) => v,
                         None => failure::bail! {
diff --git a/src/cargo/core/compiler/layout.rs b/src/cargo/core/compiler/layout.rs
index b24c1b58e8f..14b7d17a107 100644
--- a/src/cargo/core/compiler/layout.rs
+++ b/src/cargo/core/compiler/layout.rs
@@ -217,7 +217,7 @@ impl Layout {
         paths::create_dir_all(&self.examples)?;
         paths::create_dir_all(&self.build)?;
 
-        return Ok(());
+        Ok(())
     }
 
     /// Fetch the destination path for final artifacts  (`/…/target/debug`).
diff --git a/src/cargo/core/resolver/errors.rs b/src/cargo/core/resolver/errors.rs
index 6d56cb33ca8..823120e167b 100644
--- a/src/cargo/core/resolver/errors.rs
+++ b/src/cargo/core/resolver/errors.rs
@@ -252,7 +252,7 @@ pub(super) fn activation_error(
             // Maybe the user mistyped the name? Like `dep-thing` when `Dep_Thing`
             // was meant. So we try asking the registry for a `fuzzy` search for suggestions.
             let mut candidates = Vec::new();
-            if let Err(e) = registry.query(&new_dep, &mut |s| candidates.push(s.clone()), true) {
+            if let Err(e) = registry.query(&new_dep, &mut |s| candidates.push(s), true) {
                 return to_resolve_err(e);
             };
             candidates.sort_unstable_by(|a, b| a.name().cmp(&b.name()));
diff --git a/src/cargo/sources/registry/mod.rs b/src/cargo/sources/registry/mod.rs
index 7b28e9ae5a3..533f987998b 100644
--- a/src/cargo/sources/registry/mod.rs
+++ b/src/cargo/sources/registry/mod.rs
@@ -604,7 +604,7 @@ impl<'cfg> Source for RegistrySource<'cfg> {
 
     fn download(&mut self, package: PackageId) -> CargoResult<MaybePackage> {
         let hash = self.index.hash(package, &mut *self.ops)?;
-        match self.ops.download(package, &hash)? {
+        match self.ops.download(package, hash)? {
             MaybeLock::Ready(file) => self.get_pkg(package, &file).map(MaybePackage::Ready),
             MaybeLock::Download { url, descriptor } => {
                 Ok(MaybePackage::Download { url, descriptor })
@@ -614,7 +614,7 @@ impl<'cfg> Source for RegistrySource<'cfg> {
 
     fn finish_download(&mut self, package: PackageId, data: Vec<u8>) -> CargoResult<Package> {
         let hash = self.index.hash(package, &mut *self.ops)?;
-        let file = self.ops.finish_download(package, &hash, &data)?;
+        let file = self.ops.finish_download(package, hash, &data)?;
         self.get_pkg(package, &file)
     }
 
diff --git a/src/cargo/util/dependency_queue.rs b/src/cargo/util/dependency_queue.rs
index 94654950785..d0bc3da9df7 100644
--- a/src/cargo/util/dependency_queue.rs
+++ b/src/cargo/util/dependency_queue.rs
@@ -107,14 +107,14 @@ impl<N: Hash + Eq + Clone, E: Eq + Hash + Clone, V> DependencyQueue<N, E, V> {
                 .get(key)
                 .into_iter()
                 .flat_map(|it| it.values())
-                .flat_map(|set| set)
+                .flatten()
             {
                 set.extend(depth(dep, map, results).iter().cloned())
             }
 
             let slot = results.get_mut(key).unwrap();
             *slot = set;
-            return &*slot;
+            &*slot
         }
     }
 
diff --git a/src/cargo/util/toml/mod.rs b/src/cargo/util/toml/mod.rs
index ff3eedaec6e..922ff7959f0 100644
--- a/src/cargo/util/toml/mod.rs
+++ b/src/cargo/util/toml/mod.rs
@@ -954,7 +954,7 @@ impl TomlManifest {
                 .or_else(|| me.build_dependencies2.as_ref());
             process_dependencies(&mut cx, build_deps, Some(Kind::Build))?;
 
-            for (name, platform) in me.target.iter().flat_map(|t| t) {
+            for (name, platform) in me.target.iter().flatten() {
                 cx.platform = Some(name.parse()?);
                 process_dependencies(&mut cx, platform.dependencies.as_ref(), None)?;
                 let build_deps = platform
@@ -1210,7 +1210,7 @@ impl TomlManifest {
             bail!("cannot specify both [replace] and [patch]");
         }
         let mut replace = Vec::new();
-        for (spec, replacement) in self.replace.iter().flat_map(|x| x) {
+        for (spec, replacement) in self.replace.iter().flatten() {
             let mut spec = PackageIdSpec::parse(spec).chain_err(|| {
                 format!(
                     "replacements must specify a valid semver \
@@ -1252,7 +1252,7 @@ impl TomlManifest {
 
     fn patch(&self, cx: &mut Context<'_, '_>) -> CargoResult<HashMap<Url, Vec<Dependency>>> {
         let mut patch = HashMap::new();
-        for (url, deps) in self.patch.iter().flat_map(|x| x) {
+        for (url, deps) in self.patch.iter().flatten() {
             let url = match &url[..] {
                 CRATES_IO_REGISTRY => CRATES_IO_INDEX.parse().unwrap(),
                 _ => cx
@@ -1469,7 +1469,7 @@ impl DetailedTomlDependency {
             Some(id) => Dependency::parse(pkg_name, version, new_source_id, id, cx.config)?,
             None => Dependency::parse_no_deprecated(pkg_name, version, new_source_id)?,
         };
-        dep.set_features(self.features.iter().flat_map(|x| x))
+        dep.set_features(self.features.iter().flatten())
             .set_default_features(
                 self.default_features
                     .or(self.default_features2)
diff --git a/tests/testsuite/standard_lib.rs b/tests/testsuite/standard_lib.rs
index 5e6ae6126c1..6df837bd0ea 100644
--- a/tests/testsuite/standard_lib.rs
+++ b/tests/testsuite/standard_lib.rs
@@ -104,10 +104,10 @@ fn setup() -> Option<Setup> {
         .build();
     p.cargo("build").run();
 
-    return Some(Setup {
+    Some(Setup {
         rustc_wrapper: p.bin("foo"),
         real_sysroot: paths::sysroot(),
-    });
+    })
 }
 
 fn enable_build_std(e: &mut Execs, setup: &Setup, arg: Option<&str>) {