diff --git a/src/cargo/core/resolver/dep_cache.rs b/src/cargo/core/resolver/dep_cache.rs
index e20a78a66ae..ccfde1adec1 100644
--- a/src/cargo/core/resolver/dep_cache.rs
+++ b/src/cargo/core/resolver/dep_cache.rs
@@ -353,10 +353,8 @@ fn build_requirements<'a, 'b: 'a>(
         }
     }
 
-    if opts.uses_default_features {
-        if s.features().contains_key("default") {
-            reqs.require_feature(InternedString::new("default"))?;
-        }
+    if opts.uses_default_features && s.features().contains_key("default") {
+        reqs.require_feature(InternedString::new("default"))?;
     }
 
     Ok(reqs)
diff --git a/src/cargo/core/resolver/encode.rs b/src/cargo/core/resolver/encode.rs
index b60b3a20797..04d9ebd38b4 100644
--- a/src/cargo/core/resolver/encode.rs
+++ b/src/cargo/core/resolver/encode.rs
@@ -193,9 +193,9 @@ impl EncodableResolve {
         let mut map = HashMap::new();
         for (id, _) in live_pkgs.values() {
             map.entry(id.name().as_str())
-                .or_insert(HashMap::new())
+                .or_insert_with(HashMap::new)
                 .entry(id.version().to_string())
-                .or_insert(HashMap::new())
+                .or_insert_with(HashMap::new)
                 .insert(id.source_id(), *id);
         }
 
@@ -317,7 +317,7 @@ impl EncodableResolve {
         // If `checksum` was listed in `[metadata]` but we were previously
         // listed as `V2` then assume some sort of bad git merge happened, so
         // discard all checksums and let's regenerate them later.
-        if to_remove.len() > 0 && version == ResolveVersion::V2 {
+        if !to_remove.is_empty() && version == ResolveVersion::V2 {
             checksums.drain();
         }
         for k in to_remove {
@@ -542,7 +542,7 @@ impl<'a> ser::Serialize for Resolve {
                     dependencies: None,
                     replace: None,
                     checksum: match self.version() {
-                        ResolveVersion::V2 => self.checksums().get(&id).and_then(|x| x.clone()),
+                        ResolveVersion::V2 => self.checksums().get(id).and_then(|x| x.clone()),
                         ResolveVersion::V1 => None,
                     },
                 })
diff --git a/src/cargo/core/shell.rs b/src/cargo/core/shell.rs
index c0c9b13907a..0e1d878f518 100644
--- a/src/cargo/core/shell.rs
+++ b/src/cargo/core/shell.rs
@@ -377,6 +377,8 @@ mod imp {
     pub fn stderr_width() -> Option<usize> {
         unsafe {
             let mut winsize: libc::winsize = mem::zeroed();
+            // The .into() here is needed for FreeBSD which defines TIOCGWINSZ
+            // as c_uint but ioctl wants c_ulong.
             if libc::ioctl(libc::STDERR_FILENO, libc::TIOCGWINSZ.into(), &mut winsize) < 0 {
                 return None;
             }
diff --git a/src/cargo/lib.rs b/src/cargo/lib.rs
index 64e1ea2eae5..ac36549a8d6 100644
--- a/src/cargo/lib.rs
+++ b/src/cargo/lib.rs
@@ -24,6 +24,9 @@
 #![allow(clippy::trivially_copy_pass_by_ref)]
 // exhaustively destructuring ensures future fields are handled
 #![allow(clippy::unneeded_field_pattern)]
+// false positives in target-specific code, for details see
+// https://github.com/rust-lang/cargo/pull/7251#pullrequestreview-274914270
+#![allow(clippy::identity_conversion)]
 
 use std::fmt;
 use std::io;
diff --git a/src/cargo/sources/git/utils.rs b/src/cargo/sources/git/utils.rs
index 48933a8fd00..fc4b7e10ef9 100644
--- a/src/cargo/sources/git/utils.rs
+++ b/src/cargo/sources/git/utils.rs
@@ -141,7 +141,7 @@ impl GitRemote {
     fn fetch_into(&self, dst: &mut git2::Repository, cargo_config: &Config) -> CargoResult<()> {
         // Create a local anonymous remote in the repository to fetch the url
         let refspec = "refs/heads/*:refs/heads/*";
-        fetch(dst, &self.url.as_str(), refspec, cargo_config)
+        fetch(dst, self.url.as_str(), refspec, cargo_config)
     }
 
     fn clone_into(&self, dst: &Path, cargo_config: &Config) -> CargoResult<git2::Repository> {
@@ -152,7 +152,7 @@ impl GitRemote {
         let mut repo = init(dst, true)?;
         fetch(
             &mut repo,
-            &self.url.as_str(),
+            self.url.as_str(),
             "refs/heads/*:refs/heads/*",
             cargo_config,
         )?;
@@ -395,7 +395,7 @@ impl<'a> GitCheckout<'a> {
             };
             // Fetch data from origin and reset to the head commit
             let refspec = "refs/heads/*:refs/heads/*";
-            fetch(&mut repo, &url, refspec, cargo_config).chain_err(|| {
+            fetch(&mut repo, url, refspec, cargo_config).chain_err(|| {
                 internal(format!(
                     "failed to fetch submodule `{}` from {}",
                     child.name().unwrap_or(""),
diff --git a/tests/testsuite/support/mod.rs b/tests/testsuite/support/mod.rs
index f1da02e255c..063f82fae10 100644
--- a/tests/testsuite/support/mod.rs
+++ b/tests/testsuite/support/mod.rs
@@ -1157,7 +1157,7 @@ impl Execs {
         // hidden characters
         let matcher = matcher.replace("\t", "<tab>");
 
-        return matcher;
+        matcher
     }
 
     fn match_std(
@@ -1410,7 +1410,7 @@ enum MatchKind {
 /// - `[ROOT]` the path to the test directory's root
 /// - `[CWD]` is the working directory of the process that was run.
 pub fn lines_match(expected: &str, mut actual: &str) -> bool {
-    let expected = substitute_macros(&expected);
+    let expected = substitute_macros(expected);
     for (i, part) in expected.split("[..]").enumerate() {
         match actual.find(part) {
             Some(j) => {