Address clippy warnings (rust-lang#2807)

Versions of clippy that come with newer toolchains report a large number
of needless_borrows_for_generic_args. We can address these now so that
we don't have to make these changes as part of a toolchain update.

Author: tautschnig

cprover_bindings/src/goto_program/builtin.rs

@@ -329,7 +329,7 @@ impl BuiltinFn {
 /// Converters: build symbols and expressions from Builtins
 impl BuiltinFn {
     pub fn as_symbol(&self) -> Symbol {
-        Symbol::builtin_function(&self.to_string(), self.param_types(), self.return_type())
+        Symbol::builtin_function(self.to_string(), self.param_types(), self.return_type())
     }
 
     pub fn as_expr(&self) -> Expr {

kani-compiler/src/codegen_cprover_gotoc/codegen/operand.rs

@@ -561,7 +561,7 @@ impl<'tcx> GotocCtx<'tcx> {
         }
 
         let mem_place =
-            self.symbol_table.lookup(&self.alloc_map.get(&alloc).unwrap()).unwrap().to_expr();
+            self.symbol_table.lookup(self.alloc_map.get(&alloc).unwrap()).unwrap().to_expr();
         mem_place.address_of()
     }
 
@@ -579,16 +579,16 @@ impl<'tcx> GotocCtx<'tcx> {
         // initializers. For example, for a boolean static variable, the variable will have type
         // CBool and the initializer will be a single byte (a one-character array) representing the
         // bit pattern for the boolean value.
-        let alloc_typ_ref = self.ensure_struct(&struct_name, &struct_name, |ctx, _| {
+        let alloc_typ_ref = self.ensure_struct(struct_name, struct_name, |ctx, _| {
             ctx.codegen_allocation_data(alloc)
                 .iter()
                 .enumerate()
                 .map(|(i, d)| match d {
                     AllocData::Bytes(bytes) => DatatypeComponent::field(
-                        &i.to_string(),
+                        i.to_string(),
                         Type::unsigned_int(8).array_of(bytes.len()),
                     ),
-                    AllocData::Expr(e) => DatatypeComponent::field(&i.to_string(), e.typ().clone()),
+                    AllocData::Expr(e) => DatatypeComponent::field(i.to_string(), e.typ().clone()),
                 })
                 .collect()
         });

kani-compiler/src/codegen_cprover_gotoc/codegen/place.rs

@@ -268,8 +268,10 @@ impl<'tcx> GotocCtx<'tcx> {
                     | ty::Param(_)
                     | ty::Infer(_)
                     | ty::Error(_) => unreachable!("type {parent_ty:?} does not have a field"),
-                    ty::Tuple(_) => Ok(parent_expr
-                        .member(&Self::tuple_fld_name(field.index()), &self.symbol_table)),
+                    ty::Tuple(_) => {
+                        Ok(parent_expr
+                            .member(Self::tuple_fld_name(field.index()), &self.symbol_table))
+                    }
                     ty::Adt(def, _) if def.repr().simd() => Ok(self.codegen_simd_field(
                         parent_expr,
                         *field,
@@ -278,10 +280,10 @@ impl<'tcx> GotocCtx<'tcx> {
                     // if we fall here, then we are handling either a struct or a union
                     ty::Adt(def, _) => {
                         let field = &def.variants().raw[0].fields[*field];
-                        Ok(parent_expr.member(&field.name.to_string(), &self.symbol_table))
+                        Ok(parent_expr.member(field.name.to_string(), &self.symbol_table))
                     }
                     ty::Closure(..) => {
-                        Ok(parent_expr.member(&field.index().to_string(), &self.symbol_table))
+                        Ok(parent_expr.member(field.index().to_string(), &self.symbol_table))
                     }
                     ty::Generator(..) => {
                         let field_name = self.generator_field_name(field.as_usize());
@@ -299,7 +301,7 @@ impl<'tcx> GotocCtx<'tcx> {
             // if we fall here, then we are handling an enum
             TypeOrVariant::Variant(parent_var) => {
                 let field = &parent_var.fields[*field];
-                Ok(parent_expr.member(&field.name.to_string(), &self.symbol_table))
+                Ok(parent_expr.member(field.name.to_string(), &self.symbol_table))
             }
             TypeOrVariant::GeneratorVariant(_var_idx) => {
                 let field_name = self.generator_field_name(field.index());

kani-compiler/src/codegen_cprover_gotoc/codegen/typ.rs

@@ -864,7 +864,7 @@ impl<'tcx> GotocCtx<'tcx> {
             // We need to pad to the next offset
             let padding_size = next_offset - current_offset;
             let name = format!("$pad{idx}");
-            Some(DatatypeComponent::padding(&name, padding_size.bits()))
+            Some(DatatypeComponent::padding(name, padding_size.bits()))
         } else {
             None
         }
@@ -1378,7 +1378,7 @@ impl<'tcx> GotocCtx<'tcx> {
                 .iter()
                 .map(|f| {
                     DatatypeComponent::field(
-                        &f.name.to_string(),
+                        f.name.to_string(),
                         ctx.codegen_ty(f.ty(ctx.tcx, subst)),
                     )
                 })
@@ -1641,7 +1641,7 @@ impl<'tcx> GotocCtx<'tcx> {
                     None
                 } else {
                     Some(DatatypeComponent::field(
-                        &case.name.to_string(),
+                        case.name.to_string(),
                         self.codegen_enum_case_struct(
                             name,
                             pretty_name,

kani-compiler/src/codegen_cprover_gotoc/compiler_interface.rs

@@ -271,7 +271,7 @@ impl CodegenBackend for GotocCodegenBackend {
                         if let MonoItem::Fn(instance) = test_fn { instance } else { continue };
                     let metadata = gen_test_metadata(tcx, *test_desc, *instance, &base_filename);
                     let test_model_path = &metadata.goto_file.as_ref().unwrap();
-                    std::fs::copy(&model_path, &test_model_path).expect(&format!(
+                    std::fs::copy(&model_path, test_model_path).expect(&format!(
                         "Failed to copy {} to {}",
                         model_path.display(),
                         test_model_path.display()

kani-compiler/src/kani_compiler.rs

@@ -352,7 +352,7 @@ impl KaniCompiler {
     /// Write the metadata to a file
     fn store_metadata(&self, metadata: &KaniMetadata, filename: &Path) {
         debug!(?filename, "write_metadata");
-        let out_file = File::create(&filename).unwrap();
+        let out_file = File::create(filename).unwrap();
         let writer = BufWriter::new(out_file);
         if self.queries.lock().unwrap().args().output_pretty_json {
             serde_json::to_writer_pretty(writer, &metadata).unwrap();

kani-compiler/src/kani_middle/reachability.rs

@@ -725,7 +725,7 @@ mod debug {
                 debug!(?target, "dump_dot");
                 let outputs = tcx.output_filenames(());
                 let path = outputs.output_path(OutputType::Metadata).with_extension("dot");
-                let out_file = File::create(&path)?;
+                let out_file = File::create(path)?;
                 let mut writer = BufWriter::new(out_file);
                 writeln!(writer, "digraph ReachabilityGraph {{")?;
                 if target.is_empty() {

kani-driver/src/args/mod.rs

@@ -427,7 +427,7 @@ fn check_no_cargo_opt(is_set: bool, name: &str) -> Result<(), Error> {
     if is_set {
         Err(Error::raw(
             ErrorKind::UnknownArgument,
-            &format!("argument `{}` cannot be used with standalone Kani.", name),
+            format!("argument `{}` cannot be used with standalone Kani.", name),
         ))
     } else {
         Ok(())
@@ -453,7 +453,7 @@ impl ValidateArgs for StandaloneArgs {
             if !input.is_file() {
                 return Err(Error::raw(
                     ErrorKind::InvalidValue,
-                    &format!(
+                    format!(
                         "Invalid argument: Input invalid. `{}` is not a regular file.",
                         input.display()
                     ),
@@ -583,7 +583,7 @@ impl ValidateArgs for VerificationArgs {
             if out_dir.exists() && !out_dir.is_dir() {
                 return Err(Error::raw(
                     ErrorKind::InvalidValue,
-                    &format!(
+                    format!(
                         "Invalid argument: `--target-dir` argument `{}` is not a directory",
                         out_dir.display()
                     ),

kani-driver/src/args/playback_args.rs

@@ -74,7 +74,7 @@ impl ValidateArgs for KaniPlaybackArgs {
         if !self.input.is_file() {
             return Err(Error::raw(
                 ErrorKind::InvalidValue,
-                &format!(
+                format!(
                     "Invalid argument: Input invalid. `{}` is not a regular file.",
                     self.input.display()
                 ),

kani-driver/src/assess/metadata.rs

@@ -88,7 +88,7 @@ pub struct SessionError {
 /// If given the argument to so do, write the assess metadata to the target file.
 pub(crate) fn write_metadata(args: &AssessArgs, metadata: AssessMetadata) -> Result<()> {
     if let Some(path) = &args.emit_metadata {
-        let out_file = File::create(&path)?;
+        let out_file = File::create(path)?;
         let writer = BufWriter::new(out_file);
         // use pretty for now to keep things readable and debuggable, but this should change eventually
         serde_json::to_writer_pretty(writer, &metadata)?;

kani-driver/src/assess/scan.rs

@@ -179,7 +179,7 @@ fn invoke_assess(
     // Additionally, this should be `--manifest-path` but `cargo kani` doesn't support that yet.
     cmd.arg("-p").arg(package);
     cmd.arg("--enable-unstable"); // This has to be after `-p` due to an argument parsing bug in kani-driver
-    cmd.args(&["assess", "--emit-metadata"])
+    cmd.args(["assess", "--emit-metadata"])
         .arg(outfile)
         .current_dir(dir)
         .stdout(log.try_clone()?)

kani-driver/src/concrete_playback/playback.rs

@@ -84,7 +84,7 @@ fn build_test(install: &InstallType, args: &KaniPlaybackArgs) -> Result<PathBuf>
         rustc_args.push("--error-format=json".into());
     }
 
-    let mut cmd = Command::new(&install.kani_compiler()?);
+    let mut cmd = Command::new(install.kani_compiler()?);
     cmd.args(rustc_args);
 
     session::run_terminal(&args.playback.common_opts, cmd)?;

kani-driver/src/project.rs

@@ -364,6 +364,6 @@ fn metadata_with_function(
 // Note: `out_dir` is already on canonical form, so no need to invoke `try_new()`.
 fn standalone_artifact(out_dir: &Path, crate_name: &String, typ: ArtifactType) -> Artifact {
     let mut path = out_dir.join(crate_name);
-    let _ = path.set_extension(&typ);
+    let _ = path.set_extension(typ);
     Artifact { path, typ }
 }

kani-driver/src/session.rs

@@ -216,7 +216,7 @@ pub fn run_redirect(
             stdout.display()
         );
     }
-    let output_file = std::fs::File::create(&stdout)?;
+    let output_file = std::fs::File::create(stdout)?;
     cmd.stdout(output_file);
 
     let program = cmd.get_program().to_string_lossy().to_string();

kani_metadata/src/artifact.rs

@@ -56,7 +56,7 @@ pub fn convert_type(path: &Path, from: ArtifactType, to: ArtifactType) -> PathBu
     match from {
         // Artifact types that has only one extension.
         ArtifactType::Goto => {
-            result.set_extension(&to);
+            result.set_extension(to);
         }
         // Artifact types that has two extensions.
         ArtifactType::Metadata
@@ -66,7 +66,7 @@ pub fn convert_type(path: &Path, from: ArtifactType, to: ArtifactType) -> PathBu
         | ArtifactType::VTableRestriction
         | ArtifactType::PrettyNameMap => {
             result.set_extension("");
-            result.set_extension(&to);
+            result.set_extension(to);
         }
     }
     result

src/os_hacks.rs

@@ -61,8 +61,8 @@ pub fn setup_python_deps_on_ubuntu_18_04(pyroot: &Path, pkg_versions: &[&str]) -
 
     // Step 1: use `--system --prefix pyroot`. This disables the broken behavior, and creates `bin` but...
     Command::new("python3")
-        .args(&["-m", "pip", "install", "--system", "--prefix"])
-        .arg(&pyroot)
+        .args(["-m", "pip", "install", "--system", "--prefix"])
+        .arg(pyroot)
         .args(pkg_versions)
         .run()?;
 
@@ -128,7 +128,7 @@ fn setup_nixos_patchelf(kani_dir: &Path) -> Result<()> {
     // Find the correct path to link C++ stdlib:
     // `rpath=$(nix-instantiate --eval -E "(import <nixpkgs> {}).stdenv.cc.cc.lib.outPath")/lib`
     let rpath_output = Command::new("nix-instantiate")
-        .args(&["--eval", "-E", "(import <nixpkgs> {}).stdenv.cc.cc.lib.outPath"])
+        .args(["--eval", "-E", "(import <nixpkgs> {}).stdenv.cc.cc.lib.outPath"])
         .output()?;
     if !rpath_output.status.success() {
         bail!("Failed to find C++ standard library with `nix-instantiate`");
@@ -139,10 +139,10 @@ fn setup_nixos_patchelf(kani_dir: &Path) -> Result<()> {
     let rpath = format!("{rpath_prefix}/lib");
 
     let patch_interp = |file: &Path| -> Result<()> {
-        Command::new("patchelf").args(&["--set-interpreter", interp]).arg(file).run()
+        Command::new("patchelf").args(["--set-interpreter", interp]).arg(file).run()
     };
     let patch_rpath = |file: &Path| -> Result<()> {
-        Command::new("patchelf").args(&["--set-rpath", &rpath]).arg(file).run()
+        Command::new("patchelf").args(["--set-rpath", &rpath]).arg(file).run()
     };
 
     let bin = kani_dir.join("bin");

src/setup.rs

@@ -107,7 +107,7 @@ fn setup_kani_bundle(kani_dir: &Path, use_local_bundle: Option<OsString>) -> Res
             .arg("--strip-components=1")
             .arg("-zxf")
             .arg(&path)
-            .current_dir(&kani_dir)
+            .current_dir(kani_dir)
             .run()
             .context(
                 "Failed to extract tar file, try removing Kani setup located in .kani in your home directory and restarting",
@@ -118,7 +118,7 @@ fn setup_kani_bundle(kani_dir: &Path, use_local_bundle: Option<OsString>) -> Res
         fail_if_unsupported_target()?;
         let bundle = base_dir.join(filename);
         Command::new("curl")
-            .args(&["-sSLf", "-o"])
+            .args(["-sSLf", "-o"])
             .arg(&bundle)
             .arg(download_url())
             .run()
@@ -143,7 +143,7 @@ fn setup_rust_toolchain(kani_dir: &Path) -> Result<String> {
     // Currently this means we require the bundle to have been unpacked first!
     let toolchain_version = get_rust_toolchain_version(kani_dir)?;
     println!("[3/5] Installing rust toolchain version: {}", &toolchain_version);
-    Command::new("rustup").args(&["toolchain", "install", &toolchain_version]).run()?;
+    Command::new("rustup").args(["toolchain", "install", &toolchain_version]).run()?;
 
     let toolchain = home::rustup_home()?.join("toolchains").join(&toolchain_version);
 
@@ -165,7 +165,7 @@ fn setup_python_deps(kani_dir: &Path, os: &os_info::Info) -> Result<()> {
     }
 
     Command::new("python3")
-        .args(&["-m", "pip", "install", "--target"])
+        .args(["-m", "pip", "install", "--target"])
         .arg(&pyroot)
         .args(pkg_versions)
         .run()?;

tools/bookrunner/src/books.rs

@@ -88,7 +88,7 @@ impl Book {
         let summary_dir = summary_path.parent().unwrap().to_path_buf();
         let summary = fs::read_to_string(summary_path.clone()).unwrap();
         assert!(
-            summary.starts_with(&summary_start.as_str()),
+            summary.starts_with(summary_start.as_str()),
             "Error: The start of {} summary file changed.",
             self.name
         );
@@ -409,7 +409,7 @@ fn extract(
     config_paths: &mut HashSet<PathBuf>,
     default_edition: Edition,
 ) {
-    let code = fs::read_to_string(&par_from).unwrap();
+    let code = fs::read_to_string(par_from).unwrap();
     let mut examples = Examples(Vec::new());
     find_testable_code(&code, &mut examples, ErrorCodes::No, false, None);
     for mut example in examples.0 {
@@ -514,7 +514,7 @@ fn generate_text_bookrunner(bookrunner: bookrunner::Tree, path: &Path) {
         bookrunner.data.num_fail,
         bookrunner
     );
-    fs::write(&path, bookrunner_str).expect("Error: Unable to write bookrunner results");
+    fs::write(path, bookrunner_str).expect("Error: Unable to write bookrunner results");
 }
 
 /// Runs examples using Litani build.

tools/bookrunner/src/util.rs

@@ -206,7 +206,7 @@ pub fn add_verification_job(litani: &mut Litani, test_props: &TestProps) {
     // Add `--function main` so we can run these without having to amend them to add `#[kani::proof]`.
     // Some of test_props.kani_args will contains `--cbmc-args` so we should always put that last.
     kani.arg(&test_props.path)
-        .args(&["--enable-unstable", "--function", "main"])
+        .args(["--enable-unstable", "--function", "main"])
         .args(&test_props.kani_args);
     if !test_props.rustc_args.is_empty() {
         kani.env("RUSTFLAGS", test_props.rustc_args.join(" "));

tools/build-kani/src/main.rs

@@ -83,7 +83,7 @@ fn bundle_kani(dir: &Path) -> Result<()> {
 
     // 2. Kani scripts
     let scripts = dir.join("scripts");
-    std::fs::create_dir(&scripts)?;
+    std::fs::create_dir(scripts)?;
 
     // 3. Kani libraries
     let library = dir.join("library");
@@ -148,7 +148,7 @@ fn bundle_kissat(dir: &Path) -> Result<()> {
 /// This should include all files as `dir/<path>` in the tarball.
 /// e.g. `kani-1.0/bin/kani-compiler` not just `bin/kani-compiler`.
 fn create_release_bundle(dir: &Path, bundle: &str) -> Result<()> {
-    Command::new("tar").args(&["zcf", bundle]).arg(dir).run()
+    Command::new("tar").args(["zcf", bundle]).arg(dir).run()
 }
 
 /// Helper trait to fallibly run commands

tools/build-kani/src/sysroot.rs

@@ -151,7 +151,7 @@ fn build_kani_lib(
 /// Copy all the artifacts to their correct place to generate a valid sysroot.
 fn copy_artifacts(artifacts: &[Artifact], sysroot_lib: &Path, target: &str) -> Result<()> {
     // Create sysroot folder hierarchy.
-    sysroot_lib.exists().then(|| fs::remove_dir_all(&sysroot_lib));
+    sysroot_lib.exists().then(|| fs::remove_dir_all(sysroot_lib));
     let std_path = path_buf!(&sysroot_lib, "rustlib", target, "lib");
     fs::create_dir_all(&std_path).expect(&format!("Failed to create {std_path:?}"));
 

tools/compiletest/src/json.rs

@@ -63,7 +63,7 @@ pub fn extract_rendered(output: &str) -> String {
                                 String::new(),
                                 |mut output, item| {
                                     use std::fmt::Write;
-                                    let _ = write!(output, "Future breakage diagnostic:\n");
+                                    let _ = writeln!(output, "Future breakage diagnostic:");
                                     let s = item
                                         .diagnostic
                                         .rendered

tools/compiletest/src/main.rs

@@ -467,7 +467,7 @@ fn collect_rs_tests_from_dir(
     // tests themselves, they race for the privilege of
     // creating the directories and sometimes fail randomly.
     let build_dir = output_relative_path(config, relative_dir_path);
-    fs::create_dir_all(&build_dir).unwrap();
+    fs::create_dir_all(build_dir).unwrap();
 
     // Add each `.rs` file as a test, and recurse further on any
     // subdirectories we find, except for `aux` directories.
@@ -571,7 +571,7 @@ fn make_test_name(config: &Config, testpaths: &TestPaths) -> test::TestName {
     //    ui/foo/bar/baz.rs
     let path = PathBuf::from(config.src_base.file_name().unwrap())
         .join(&testpaths.relative_dir)
-        .join(&testpaths.file.file_name().unwrap());
+        .join(testpaths.file.file_name().unwrap());
 
     test::DynTestName(format!("[{}] {}", config.mode, path.display()))
 }