diff --git a/src/compiler/args.rs b/src/compiler/args.rs
index a9c81580..e551c0f8 100644
--- a/src/compiler/args.rs
+++ b/src/compiler/args.rs
@@ -11,7 +11,7 @@ pub type ArgParseResult<T> = StdResult<T, ArgParseError>;
 pub type ArgToStringResult = StdResult<String, ArgToStringError>;
 pub type PathTransformerFn<'a> = &'a mut dyn FnMut(&Path) -> Option<String>;
 
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Eq)]
 pub enum ArgParseError {
     UnexpectedEndOfArgs,
     InvalidUnicode(OsString),
@@ -35,7 +35,7 @@ impl Error for ArgParseError {
     }
 }
 
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Eq)]
 pub enum ArgToStringError {
     FailedPathTransform(PathBuf),
     InvalidUnicode(OsString),
@@ -69,7 +69,7 @@ pub type Delimiter = Option<u8>;
 /// on the different kinds of argument). `Flag`s may contain a simple
 /// variant which influences how to do caching, whereas `WithValue`s could
 /// be a struct variant with parsed data from the value.
-#[derive(PartialEq, Clone, Debug)]
+#[derive(PartialEq, Eq, Clone, Debug)]
 pub enum Argument<T> {
     /// Unknown non-flag argument ; e.g. "foo"
     Raw(OsString),
@@ -83,7 +83,7 @@ pub enum Argument<T> {
 }
 
 /// How a value is passed to an argument with a value.
-#[derive(PartialEq, Clone, Debug)]
+#[derive(PartialEq, Eq, Clone, Debug)]
 pub enum ArgDisposition {
     /// As "-arg value"
     Separated,
@@ -299,7 +299,7 @@ macro_rules! ArgData {
 
     // PartialEq necessary for tests
     { pub $( $tok:tt )+ } => {
-        #[derive(Clone, Debug, PartialEq)]
+        #[derive(Clone, Debug, PartialEq, Eq)]
         pub enum ArgData {
             $($tok)+
         }
@@ -387,7 +387,7 @@ pub fn split_os_string_arg(val: OsString, split: &str) -> ArgParseResult<(String
 }
 
 /// The description of how an argument may be parsed
-#[derive(PartialEq, Clone, Debug)]
+#[derive(PartialEq, Eq, Clone, Debug)]
 pub enum ArgInfo<T> {
     /// An simple flag argument, of the form "-foo"
     Flag(&'static str, T),
diff --git a/src/compiler/c.rs b/src/compiler/c.rs
index bcceca1d..5d39dff2 100644
--- a/src/compiler/c.rs
+++ b/src/compiler/c.rs
@@ -60,7 +60,7 @@ where
     compiler: I,
 }
 
-#[derive(Debug, PartialEq, Clone, Copy)]
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
 pub enum Language {
     C,
     Cxx,
@@ -70,7 +70,7 @@ pub enum Language {
 }
 
 /// Artifact produced by a C/C++ compiler.
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub struct ArtifactDesciptor {
     /// Path to the artifact.
     pub path: PathBuf,
@@ -80,7 +80,7 @@ pub struct ArtifactDesciptor {
 
 /// The results of parsing a compiler commandline.
 #[allow(dead_code)]
-#[derive(Debug, PartialEq, Clone)]
+#[derive(Debug, PartialEq, Eq, Clone)]
 pub struct ParsedArguments {
     /// The input source file.
     pub input: PathBuf,
@@ -166,7 +166,7 @@ struct CCompilation<I: CCompilerImpl> {
 }
 
 /// Supported C compilers.
-#[derive(Debug, PartialEq, Clone)]
+#[derive(Debug, PartialEq, Eq, Clone)]
 pub enum CCompilerKind {
     /// GCC
     Gcc,
diff --git a/src/compiler/compiler.rs b/src/compiler/compiler.rs
index 166f000e..015963d3 100644
--- a/src/compiler/compiler.rs
+++ b/src/compiler/compiler.rs
@@ -79,7 +79,7 @@ impl CompileCommand {
 }
 
 /// Supported compilers.
-#[derive(Debug, PartialEq, Clone)]
+#[derive(Debug, PartialEq, Eq, Clone)]
 pub enum CompilerKind {
     /// A C compiler.
     C(CCompilerKind),
@@ -691,7 +691,7 @@ pub struct HashResult {
 }
 
 /// Possible results of parsing compiler arguments.
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Eq)]
 pub enum CompilerArguments<T> {
     /// Commandline can be handled.
     Ok(T),
@@ -720,7 +720,7 @@ macro_rules! try_or_cannot_cache {
 }
 
 /// Specifics about distributed compilation.
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Eq)]
 pub enum DistType {
     /// Distribution was not enabled.
     NoDist,
@@ -731,7 +731,7 @@ pub enum DistType {
 }
 
 /// Specifics about cache misses.
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Eq)]
 pub enum MissType {
     /// The compilation was not found in the cache, nothing more.
     Normal,
@@ -772,7 +772,7 @@ pub enum CompileResult {
 }
 
 /// The state of `--color` options passed to a compiler.
-#[derive(Clone, Copy, Debug, PartialEq, Serialize, Deserialize)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub enum ColorMode {
     Off,
     On,
@@ -818,14 +818,14 @@ impl PartialEq<CompileResult> for CompileResult {
 }
 
 /// Can this result be stored in cache?
-#[derive(Copy, Clone, Debug, PartialEq)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub enum Cacheable {
     Yes,
     No,
 }
 
 /// Control of caching behavior.
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Eq)]
 pub enum CacheControl {
     /// Default caching behavior.
     Default,
diff --git a/src/compiler/msvc.rs b/src/compiler/msvc.rs
index 60e6e497..4320974a 100644
--- a/src/compiler/msvc.rs
+++ b/src/compiler/msvc.rs
@@ -36,7 +36,7 @@ use crate::errors::*;
 /// A struct on which to implement `CCompilerImpl`.
 ///
 /// Needs a little bit of state just to persist `includes_prefix`.
-#[derive(Debug, PartialEq, Clone)]
+#[derive(Debug, PartialEq, Eq, Clone)]
 pub struct Msvc {
     /// The prefix used in the output of `-showIncludes`.
     pub includes_prefix: String,
diff --git a/src/compiler/rust.rs b/src/compiler/rust.rs
index e9937b57..f18f3161 100644
--- a/src/compiler/rust.rs
+++ b/src/compiler/rust.rs
@@ -180,7 +180,7 @@ pub struct RustCompilation {
 }
 
 // The selection of crate types for this compilation
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub struct CrateTypes {
     rlib: bool,
     staticlib: bool,
@@ -3148,7 +3148,8 @@ proc_macro false
             o => panic!("Got unexpected parse result: {:?}", o),
         };
         // Just use empty files for sources.
-        for src in ["foo.rs"].iter() {
+        {
+            let src = &"foo.rs";
             let s = format!("Failed to create {}", src);
             f.touch(src).expect(&s);
         }
diff --git a/tests/system.rs b/tests/system.rs
index c93e5852..dac6f6d8 100644
--- a/tests/system.rs
+++ b/tests/system.rs
@@ -89,7 +89,7 @@ const OUTPUT: &str = "test.o";
 // Copy the source files into the tempdir so we can compile with relative paths, since the commandline winds up in the hash key.
 fn copy_to_tempdir(inputs: &[&str], tempdir: &Path) {
     for f in inputs {
-        let original_source_file = Path::new(file!()).parent().unwrap().join(&*f);
+        let original_source_file = Path::new(file!()).parent().unwrap().join(f);
         let source_file = tempdir.join(f);
         trace!("fs::copy({:?}, {:?})", original_source_file, source_file);
         fs::copy(&original_source_file, &source_file).unwrap();