Fix needless_pass_by_value lint

This also gets rid of some unneeded cloning

Author: nyurik

Cargo.toml

@@ -85,7 +85,6 @@ wildcard_imports = "allow"
 # TODO
 borrow_as_ptr = "allow"
 trivially_copy_pass_by_ref = "allow"
-needless_pass_by_value = "allow"
 unused_self = "allow"
 
 # Theese seem to be ok to ignore for now

bindgen-tests/tests/parse_callbacks/item_discovery_callback/mod.rs

@@ -76,10 +76,10 @@ pub fn test_item_discovery_callback() {
         ),
     ]);
 
-    compare_item_caches(info.borrow().clone(), expected);
+    compare_item_caches(&info.borrow(), &expected);
 }
 
-pub fn compare_item_caches(generated: ItemCache, expected: ItemCache) {
+pub fn compare_item_caches(generated: &ItemCache, expected: &ItemCache) {
     // We can't use a simple Eq::eq comparison because of two reasons:
     // - anonymous structs/unions will have a final name generated by bindgen which may change
     //   if the header file or the bindgen logic is altered
@@ -89,8 +89,8 @@ pub fn compare_item_caches(generated: ItemCache, expected: ItemCache) {
             compare_item_info(
                 expected_item,
                 generated_item,
-                &expected,
-                &generated,
+                expected,
+                generated,
             )
         });
 

bindgen-tests/tests/quickchecking/src/lib.rs

@@ -37,7 +37,7 @@ static CONTEXT: Mutex<Context> = Mutex::new(Context { output_path: None });
 // Passes fuzzed header to the `csmith-fuzzing/predicate.py` script, returns
 // output of the associated command.
 fn run_predicate_script(
-    header: fuzzers::HeaderC,
+    header: &fuzzers::HeaderC,
 ) -> Result<Output, Box<dyn Error>> {
     let dir = Builder::new().prefix("bindgen_prop").tempdir()?;
     let header_path = dir.path().join("prop_test.h");
@@ -77,8 +77,9 @@ fn run_predicate_script(
 // Generatable property. Pass generated headers off to run through the
 // `csmith-fuzzing/predicate.py` script. Success is measured by the success
 // status of that command.
+#[allow(clippy::needless_pass_by_value)]
 fn bindgen_prop(header: fuzzers::HeaderC) -> TestResult {
-    match run_predicate_script(header) {
+    match run_predicate_script(&header) {
         Ok(o) => TestResult::from_bool(o.status.success()),
         Err(e) => {
             println!("{e:?}");

bindgen/codegen/dyngen.rs

@@ -75,7 +75,7 @@ impl DynamicItems {
 
     pub(crate) fn get_tokens(
         &self,
-        lib_ident: Ident,
+        lib_ident: &Ident,
         ctx: &BindgenContext,
     ) -> TokenStream {
         let struct_members = &self.struct_members;
@@ -130,15 +130,15 @@ impl DynamicItems {
     #[allow(clippy::too_many_arguments)]
     pub(crate) fn push_func(
         &mut self,
-        ident: Ident,
+        ident: &Ident,
         abi: ClangAbi,
         is_variadic: bool,
         is_required: bool,
-        args: Vec<TokenStream>,
-        args_identifiers: Vec<TokenStream>,
-        ret: TokenStream,
-        ret_ty: TokenStream,
-        attributes: Vec<TokenStream>,
+        args: &[TokenStream],
+        args_identifiers: &[TokenStream],
+        ret: &TokenStream,
+        ret_ty: &TokenStream,
+        attributes: &[TokenStream],
         ctx: &BindgenContext,
     ) {
         if !is_variadic {
@@ -205,8 +205,8 @@ impl DynamicItems {
 
     pub fn push_var(
         &mut self,
-        ident: Ident,
-        ty: TokenStream,
+        ident: &Ident,
+        ty: &TokenStream,
         is_required: bool,
         wrap_unsafe_ops: bool,
     ) {

bindgen/codegen/helpers.rs

@@ -52,7 +52,7 @@ pub(crate) mod attributes {
         }
     }
 
-    pub(crate) fn doc(comment: String) -> TokenStream {
+    pub(crate) fn doc(comment: &str) -> TokenStream {
         if comment.is_empty() {
             quote!()
         } else {

bindgen/codegen/impl_debug.rs

@@ -130,7 +130,7 @@ impl<'a> ImplDebug<'a> for Item {
 
         fn debug_print(
             name: &str,
-            name_ident: proc_macro2::TokenStream,
+            name_ident: &proc_macro2::TokenStream,
         ) -> Option<(String, Vec<proc_macro2::TokenStream>)> {
             Some((
                 format!("{name}: {{:?}}"),
@@ -154,13 +154,13 @@ impl<'a> ImplDebug<'a> for Item {
             TypeKind::ObjCInterface(..) |
             TypeKind::ObjCId |
             TypeKind::Comp(..) |
-            TypeKind::ObjCSel => debug_print(name, quote! { #name_ident }),
+            TypeKind::ObjCSel => debug_print(name, &quote! { #name_ident }),
 
             TypeKind::TemplateInstantiation(ref inst) => {
                 if inst.is_opaque(ctx, self) {
                     Some((format!("{name}: opaque"), vec![]))
                 } else {
-                    debug_print(name, quote! { #name_ident })
+                    debug_print(name, &quote! { #name_ident })
                 }
             }
 
@@ -177,7 +177,7 @@ impl<'a> ImplDebug<'a> for Item {
                     ctx.options().rust_features().larger_arrays
                 {
                     // The simple case
-                    debug_print(name, quote! { #name_ident })
+                    debug_print(name, &quote! { #name_ident })
                 } else if ctx.options().use_core {
                     // There is no String in core; reducing field visibility to avoid breaking
                     // no_std setups.
@@ -233,7 +233,7 @@ impl<'a> ImplDebug<'a> for Item {
                     {
                         Some((format!("{name}: FunctionPointer"), vec![]))
                     }
-                    _ => debug_print(name, quote! { #name_ident }),
+                    _ => debug_print(name, &quote! { #name_ident }),
                 }
             }
 

bindgen/codegen/impl_partialeq.rs

@@ -76,7 +76,7 @@ fn gen_field(
     name: &str,
 ) -> proc_macro2::TokenStream {
     fn quote_equals(
-        name_ident: proc_macro2::Ident,
+        name_ident: &proc_macro2::Ident,
     ) -> proc_macro2::TokenStream {
         quote! { self.#name_ident == other.#name_ident }
     }
@@ -100,23 +100,23 @@ fn gen_field(
         TypeKind::Comp(..) |
         TypeKind::Pointer(_) |
         TypeKind::Function(..) |
-        TypeKind::Opaque => quote_equals(name_ident),
+        TypeKind::Opaque => quote_equals(&name_ident),
 
         TypeKind::TemplateInstantiation(ref inst) => {
             if inst.is_opaque(ctx, ty_item) {
                 quote! {
                     &self. #name_ident [..] == &other. #name_ident [..]
                 }
             } else {
-                quote_equals(name_ident)
+                quote_equals(&name_ident)
             }
         }
 
         TypeKind::Array(_, len) => {
             if len <= RUST_DERIVE_IN_ARRAY_LIMIT ||
                 ctx.options().rust_features().larger_arrays
             {
-                quote_equals(name_ident)
+                quote_equals(&name_ident)
             } else {
                 quote! {
                     &self. #name_ident [..] == &other. #name_ident [..]