Fix clippy warning (1.40 -> 1.54)

The clippy.toml suppresses warnings added in newer rust versions,
so fixing the documented MSRV also shows new warnings.

src/bindgen/cdecl.rs

@@ -296,7 +296,7 @@ impl CDecl {
                     ) {
                         let align_length = out.line_length_for_align();
                         out.push_set_spaces(align_length);
-                        for (i, &(ref arg_ident, ref arg_ty)) in args.iter().enumerate() {
+                        for (i, (arg_ident, arg_ty)) in args.iter().enumerate() {
                             if i != 0 {
                                 out.write(",");
                                 out.new_line();
@@ -315,7 +315,7 @@ impl CDecl {
                         config: &Config,
                         args: &[(Option<String>, CDecl)],
                     ) {
-                        for (i, &(ref arg_ident, ref arg_ty)) in args.iter().enumerate() {
+                        for (i, (arg_ident, arg_ty)) in args.iter().enumerate() {
                             if i != 0 {
                                 out.write(", ");
                             }

src/bindgen/dependencies.rs

@@ -26,17 +26,15 @@ impl Dependencies {
         // Sort untagged enums and opaque structs into their own layers because they don't
         // depend on each other or anything else.
         let ordering = |a: &ItemContainer, b: &ItemContainer| match (a, b) {
-            (&ItemContainer::Enum(ref x), &ItemContainer::Enum(ref y))
+            (ItemContainer::Enum(x), ItemContainer::Enum(y))
                 if x.tag.is_none() && y.tag.is_none() =>
             {
                 x.path.cmp(&y.path)
             }
-            (&ItemContainer::Enum(ref x), _) if x.tag.is_none() => Ordering::Less,
+            (ItemContainer::Enum(x), _) if x.tag.is_none() => Ordering::Less,
-            (_, &ItemContainer::Enum(ref x)) if x.tag.is_none() => Ordering::Greater,
+            (_, ItemContainer::Enum(x)) if x.tag.is_none() => Ordering::Greater,
 
-            (&ItemContainer::OpaqueItem(ref x), &ItemContainer::OpaqueItem(ref y)) => {
+            (ItemContainer::OpaqueItem(x), ItemContainer::OpaqueItem(y)) => x.path.cmp(&y.path),
-                x.path.cmp(&y.path)
-            }
             (&ItemContainer::OpaqueItem(_), _) => Ordering::Less,
             (_, &ItemContainer::OpaqueItem(_)) => Ordering::Greater,
 

src/bindgen/ir/annotation.rs

@@ -130,19 +130,19 @@ impl AnnotationSet {
 
     pub fn list(&self, name: &str) -> Option<Vec<String>> {
         match self.annotations.get(name) {
-            Some(&AnnotationValue::List(ref x)) => Some(x.clone()),
+            Some(AnnotationValue::List(x)) => Some(x.clone()),
             _ => None,
         }
     }
     pub fn atom(&self, name: &str) -> Option<Option<String>> {
         match self.annotations.get(name) {
-            Some(&AnnotationValue::Atom(ref x)) => Some(x.clone()),
+            Some(AnnotationValue::Atom(x)) => Some(x.clone()),
             _ => None,
         }
     }
     pub fn bool(&self, name: &str) -> Option<bool> {
         match self.annotations.get(name) {
-            Some(&AnnotationValue::Bool(ref x)) => Some(*x),
+            Some(AnnotationValue::Bool(x)) => Some(*x),
             _ => None,
         }
     }
@@ -152,7 +152,7 @@ impl AnnotationSet {
         T: Default + FromStr,
     {
         match self.annotations.get(name) {
-            Some(&AnnotationValue::Atom(ref x)) => Some(
+            Some(AnnotationValue::Atom(x)) => Some(
                 x.as_ref()
                     .map_or(T::default(), |y| y.parse::<T>().ok().unwrap()),
             ),

src/bindgen/ir/item.rs

@@ -219,12 +219,12 @@ impl<T: Item + Clone> ItemMap<T> {
         F: FnMut(&T),
     {
         match self.data.get(path) {
-            Some(&ItemValue::Cfg(ref items)) => {
+            Some(ItemValue::Cfg(items)) => {
                 for item in items {
                     callback(item);
                 }
             }
-            Some(&ItemValue::Single(ref item)) => {
+            Some(ItemValue::Single(item)) => {
                 callback(item);
             }
             None => {}

src/main.rs

@@ -157,7 +157,7 @@ fn main() {
                 .long("lang")
                 .value_name("LANGUAGE")
                 .help("Specify the language to output bindings in")
-                .possible_values(&["c++", "C++", "c", "C", "cython", "Cython"]),
+                .possible_values(["c++", "C++", "c", "C", "cython", "Cython"]),
         )
         .arg(
             Arg::new("cpp-compat")
@@ -176,7 +176,7 @@ fn main() {
                 .long("style")
                 .value_name("STYLE")
                 .help("Specify the declaration style to use for bindings")
-                .possible_values(&["Both", "both", "Tag", "tag", "Type", "type"]),
+                .possible_values(["Both", "both", "Tag", "tag", "Type", "type"]),
         )
         .arg(
             Arg::new("d")
@@ -253,7 +253,7 @@ fn main() {
                     "Specify the profile to use when expanding macros. \
                      Has no effect otherwise."
                 )
-                .possible_values(&["Debug", "debug", "Release", "release"]),
+                .possible_values(["Debug", "debug", "Release", "release"]),
         )
         .arg(
             Arg::new("quiet")

tests/tests.rs

@@ -23,7 +23,7 @@ fn run_cbindgen(
     style: Option<Style>,
 ) -> Vec<u8> {
     let program = Path::new(cbindgen_path);
-    let mut command = Command::new(&program);
+    let mut command = Command::new(program);
     match language {
         Language::Cxx => {}
         Language::C => {