Fix clippy lints

15 files changed, 142 insertions, 156 deletions

diff --git a/build_system/src/build.rs b/build_system/src/build.rs
index e98377f15a9..ecc4c1b2fe2 100644
--- a/build_system/src/build.rs
+++ b/build_system/src/build.rs
@@ -33,7 +33,7 @@ impl BuildArg {
                 }
                 arg => {
                     if !build_arg.config_info.parse_argument(arg, &mut args)? {
-                        return Err(format!("Unknown argument `{}`", arg));
+                        return Err(format!("Unknown argument `{arg}`"));
                     }
                 }
             }
@@ -105,14 +105,14 @@ pub fn create_build_sysroot_content(start_dir: &Path) -> Result<(), String> {
     if !start_dir.is_dir() {
         create_dir(start_dir)?;
     }
-    copy_file("build_system/build_sysroot/Cargo.toml", &start_dir.join("Cargo.toml"))?;
-    copy_file("build_system/build_sysroot/Cargo.lock", &start_dir.join("Cargo.lock"))?;
+    copy_file("build_system/build_sysroot/Cargo.toml", start_dir.join("Cargo.toml"))?;
+    copy_file("build_system/build_sysroot/Cargo.lock", start_dir.join("Cargo.lock"))?;
 
     let src_dir = start_dir.join("src");
     if !src_dir.is_dir() {
         create_dir(&src_dir)?;
     }
-    copy_file("build_system/build_sysroot/lib.rs", &start_dir.join("src/lib.rs"))
+    copy_file("build_system/build_sysroot/lib.rs", start_dir.join("src/lib.rs"))
 }
 
 pub fn build_sysroot(env: &HashMap<String, String>, config: &ConfigInfo) -> Result<(), String> {
@@ -169,7 +169,7 @@ pub fn build_sysroot(env: &HashMap<String, String>, config: &ConfigInfo) -> Resu
         run_command(&[&"cp", &"-r", &dir_to_copy, &sysroot_path], None).map(|_| ())
     };
     walk_dir(
-        start_dir.join(&format!("target/{}/{}/deps", config.target_triple, channel)),
+        start_dir.join(format!("target/{}/{}/deps", config.target_triple, channel)),
         &mut copier.clone(),
         &mut copier,
         false,
diff --git a/build_system/src/clean.rs b/build_system/src/clean.rs
index 768a78e789e..a441ed613f9 100644
--- a/build_system/src/clean.rs
+++ b/build_system/src/clean.rs
@@ -17,12 +17,12 @@ enum CleanArg {
 impl CleanArg {
     fn new() -> Result<Self, String> {
         // We skip the binary and the "clean" option.
-        for arg in std::env::args().skip(2) {
+        if let Some(arg) = std::env::args().nth(2) {
             return match arg.as_str() {
                 "all" => Ok(Self::All),
                 "ui-tests" => Ok(Self::UiTests),
                 "--help" => Ok(Self::Help),
-                a => Err(format!("Unknown argument `{}`", a)),
+                a => Err(format!("Unknown argument `{a}`")),
             };
         }
         Ok(Self::default())
diff --git a/build_system/src/clone_gcc.rs b/build_system/src/clone_gcc.rs
index b49dd47f352..ee683df419c 100644
--- a/build_system/src/clone_gcc.rs
+++ b/build_system/src/clone_gcc.rs
@@ -43,7 +43,7 @@ impl Args {
                 }
                 arg => {
                     if !command_args.config_info.parse_argument(arg, &mut args)? {
-                        return Err(format!("Unknown option {}", arg));
+                        return Err(format!("Unknown option {arg}"));
                     }
                 }
             }
@@ -52,7 +52,7 @@ impl Args {
             Some(p) => p.into(),
             None => PathBuf::from("./gcc"),
         };
-        return Ok(Some(command_args));
+        Ok(Some(command_args))
     }
 }
 
@@ -64,7 +64,7 @@ pub fn run() -> Result<(), String> {
     let result = git_clone("https://github.com/rust-lang/gcc", Some(&args.out_path), false)?;
     if result.ran_clone {
         let gcc_commit = args.config_info.get_gcc_commit()?;
-        println!("Checking out GCC commit `{}`...", gcc_commit);
+        println!("Checking out GCC commit `{gcc_commit}`...");
         run_command_with_output(
             &[&"git", &"checkout", &gcc_commit],
             Some(Path::new(&result.repo_dir)),
diff --git a/build_system/src/config.rs b/build_system/src/config.rs
index 4f9fcc97151..650c030ca53 100644
--- a/build_system/src/config.rs
+++ b/build_system/src/config.rs
@@ -66,7 +66,7 @@ impl ConfigFile {
                         "Expected a boolean for `download-gccjit`",
                     );
                 }
-                _ => return failed_config_parsing(config_file, &format!("Unknown key `{}`", key)),
+                _ => return failed_config_parsing(config_file, &format!("Unknown key `{key}`")),
             }
         }
         match (config.gcc_path.as_mut(), config.download_gccjit) {
@@ -86,9 +86,7 @@ impl ConfigFile {
                 let path = Path::new(gcc_path);
                 *gcc_path = path
                     .canonicalize()
-                    .map_err(|err| {
-                        format!("Failed to get absolute path of `{}`: {:?}", gcc_path, err)
-                    })?
+                    .map_err(|err| format!("Failed to get absolute path of `{gcc_path}`: {err:?}"))?
                     .display()
                     .to_string();
             }
@@ -175,7 +173,7 @@ impl ConfigInfo {
             "--sysroot-panic-abort" => self.sysroot_panic_abort = true,
             "--gcc-path" => match args.next() {
                 Some(arg) if !arg.is_empty() => {
-                    self.gcc_path = Some(arg.into());
+                    self.gcc_path = Some(arg);
                 }
                 _ => {
                     return Err("Expected a value after `--gcc-path`, found nothing".to_string());
@@ -244,7 +242,7 @@ impl ConfigInfo {
         let libgccjit_so = output_dir.join(libgccjit_so_name);
         if !libgccjit_so.is_file() && !self.no_download {
             // Download time!
-            let tempfile_name = format!("{}.download", libgccjit_so_name);
+            let tempfile_name = format!("{libgccjit_so_name}.download");
             let tempfile = output_dir.join(&tempfile_name);
             let is_in_ci = std::env::var("GITHUB_ACTIONS").is_ok();
 
@@ -262,14 +260,14 @@ impl ConfigInfo {
                 )
             })?;
 
-            println!("Downloaded libgccjit.so version {} successfully!", commit);
+            println!("Downloaded libgccjit.so version {commit} successfully!");
             // We need to create a link named `libgccjit.so.0` because that's what the linker is
             // looking for.
-            create_symlink(&libgccjit_so, output_dir.join(&format!("{}.0", libgccjit_so_name)))?;
+            create_symlink(&libgccjit_so, output_dir.join(format!("{libgccjit_so_name}.0")))?;
         }
 
         let gcc_path = output_dir.display().to_string();
-        println!("Using `{}` as path for libgccjit", gcc_path);
+        println!("Using `{gcc_path}` as path for libgccjit");
         self.gcc_path = Some(gcc_path);
         Ok(())
     }
@@ -286,8 +284,7 @@ impl ConfigInfo {
         // since we already have everything we need.
         if let Some(gcc_path) = &self.gcc_path {
             println!(
-                "`--gcc-path` was provided, ignoring config file. Using `{}` as path for libgccjit",
-                gcc_path
+                "`--gcc-path` was provided, ignoring config file. Using `{gcc_path}` as path for libgccjit"
             );
             return Ok(());
         }
@@ -343,7 +340,7 @@ impl ConfigInfo {
         self.dylib_ext = match os_name.as_str() {
             "Linux" => "so",
             "Darwin" => "dylib",
-            os => return Err(format!("unsupported OS `{}`", os)),
+            os => return Err(format!("unsupported OS `{os}`")),
         }
         .to_string();
         let rustc = match env.get("RUSTC") {
@@ -355,10 +352,10 @@ impl ConfigInfo {
             None => return Err("no host found".to_string()),
         };
 
-        if self.target_triple.is_empty() {
-            if let Some(overwrite) = env.get("OVERWRITE_TARGET_TRIPLE") {
-                self.target_triple = overwrite.clone();
-            }
+        if self.target_triple.is_empty()
+            && let Some(overwrite) = env.get("OVERWRITE_TARGET_TRIPLE")
+        {
+            self.target_triple = overwrite.clone();
         }
         if self.target_triple.is_empty() {
             self.target_triple = self.host_triple.clone();
@@ -378,7 +375,7 @@ impl ConfigInfo {
         }
 
         let current_dir =
-            std_env::current_dir().map_err(|error| format!("`current_dir` failed: {:?}", error))?;
+            std_env::current_dir().map_err(|error| format!("`current_dir` failed: {error:?}"))?;
         let channel = if self.channel == Channel::Release {
             "release"
         } else if let Some(channel) = env.get("CHANNEL") {
@@ -391,15 +388,15 @@ impl ConfigInfo {
         self.cg_backend_path = current_dir
             .join("target")
             .join(channel)
-            .join(&format!("librustc_codegen_gcc.{}", self.dylib_ext))
+            .join(format!("librustc_codegen_gcc.{}", self.dylib_ext))
             .display()
             .to_string();
         self.sysroot_path =
-            current_dir.join(&get_sysroot_dir()).join("sysroot").display().to_string();
+            current_dir.join(get_sysroot_dir()).join("sysroot").display().to_string();
         if let Some(backend) = &self.backend {
             // This option is only used in the rust compiler testsuite. The sysroot is handled
             // by its build system directly so no need to set it ourselves.
-            rustflags.push(format!("-Zcodegen-backend={}", backend));
+            rustflags.push(format!("-Zcodegen-backend={backend}"));
         } else {
             rustflags.extend_from_slice(&[
                 "--sysroot".to_string(),
@@ -412,10 +409,10 @@ impl ConfigInfo {
         // We have a different environment variable than RUSTFLAGS to make sure those flags are
         // only sent to rustc_codegen_gcc and not the LLVM backend.
         if let Some(cg_rustflags) = env.get("CG_RUSTFLAGS") {
-            rustflags.extend_from_slice(&split_args(&cg_rustflags)?);
+            rustflags.extend_from_slice(&split_args(cg_rustflags)?);
         }
         if let Some(test_flags) = env.get("TEST_FLAGS") {
-            rustflags.extend_from_slice(&split_args(&test_flags)?);
+            rustflags.extend_from_slice(&split_args(test_flags)?);
         }
 
         if let Some(linker) = linker {
@@ -438,8 +435,8 @@ impl ConfigInfo {
         env.insert("RUSTC_LOG".to_string(), "warn".to_string());
 
         let sysroot = current_dir
-            .join(&get_sysroot_dir())
-            .join(&format!("sysroot/lib/rustlib/{}/lib", self.target_triple));
+            .join(get_sysroot_dir())
+            .join(format!("sysroot/lib/rustlib/{}/lib", self.target_triple));
         let ld_library_path = format!(
             "{target}:{sysroot}:{gcc_path}",
             target = self.cargo_target_dir,
@@ -505,7 +502,7 @@ fn download_gccjit(
     with_progress_bar: bool,
 ) -> Result<(), String> {
     let url = if std::env::consts::OS == "linux" && std::env::consts::ARCH == "x86_64" {
-        format!("https://github.com/rust-lang/gcc/releases/download/master-{}/libgccjit.so", commit)
+        format!("https://github.com/rust-lang/gcc/releases/download/master-{commit}/libgccjit.so")
     } else {
         eprintln!(
             "\
@@ -518,7 +515,7 @@ to `download-gccjit = false` and set `gcc-path` to the appropriate directory."
         ));
     };
 
-    println!("Downloading `{}`...", url);
+    println!("Downloading `{url}`...");
 
     // Try curl. If that fails and we are on windows, fallback to PowerShell.
     let mut ret = run_command_with_output(
@@ -538,7 +535,7 @@ to `download-gccjit = false` and set `gcc-path` to the appropriate directory."
             if with_progress_bar { &"--progress-bar" } else { &"-s" },
             &url.as_str(),
         ],
-        Some(&output_dir),
+        Some(output_dir),
     );
     if ret.is_err() && cfg!(windows) {
         eprintln!("Fallback to PowerShell");
@@ -549,12 +546,11 @@ to `download-gccjit = false` and set `gcc-path` to the appropriate directory."
                 &"-Command",
                 &"[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12;",
                 &format!(
-                    "(New-Object System.Net.WebClient).DownloadFile('{}', '{}')",
-                    url, tempfile_name,
+                    "(New-Object System.Net.WebClient).DownloadFile('{url}', '{tempfile_name}')",
                 )
                 .as_str(),
             ],
-            Some(&output_dir),
+            Some(output_dir),
         );
     }
     ret
diff --git a/build_system/src/fmt.rs b/build_system/src/fmt.rs
index de310a6a30f..7e6594f50f9 100644
--- a/build_system/src/fmt.rs
+++ b/build_system/src/fmt.rs
@@ -16,21 +16,21 @@ fn show_usage() {
 pub fn run() -> Result<(), String> {
     let mut check = false;
     // We skip binary name and the `info` command.
-    let mut args = std::env::args().skip(2);
-    while let Some(arg) = args.next() {
+    let args = std::env::args().skip(2);
+    for arg in args {
         match arg.as_str() {
             "--help" => {
                 show_usage();
                 return Ok(());
             }
             "--check" => check = true,
-            _ => return Err(format!("Unknown option {}", arg)),
+            _ => return Err(format!("Unknown option {arg}")),
         }
     }
 
     let cmd: &[&dyn AsRef<OsStr>] =
         if check { &[&"cargo", &"fmt", &"--check"] } else { &[&"cargo", &"fmt"] };
 
-    run_command_with_output(cmd, Some(&Path::new(".")))?;
-    run_command_with_output(cmd, Some(&Path::new("build_system")))
+    run_command_with_output(cmd, Some(Path::new(".")))?;
+    run_command_with_output(cmd, Some(Path::new("build_system")))
 }
diff --git a/build_system/src/fuzz.rs b/build_system/src/fuzz.rs
index f170453bfe4..453211366b3 100644
--- a/build_system/src/fuzz.rs
+++ b/build_system/src/fuzz.rs
@@ -56,7 +56,7 @@ pub fn run() -> Result<(), String> {
                 )
                 .map_err(|err| (format!("Fuzz thread count not a number {err:?}!")))?;
             }
-            _ => return Err(format!("Unknown option {}", arg)),
+            _ => return Err(format!("Unknown option {arg}")),
         }
     }
 
@@ -70,11 +70,11 @@ pub fn run() -> Result<(), String> {
 
     // Ensure that we are on the newest rustlantis commit.
     let cmd: &[&dyn AsRef<OsStr>] = &[&"git", &"pull", &"origin"];
-    run_command_with_output(cmd, Some(&Path::new("clones/rustlantis")))?;
+    run_command_with_output(cmd, Some(Path::new("clones/rustlantis")))?;
 
     // Build the release version of rustlantis
     let cmd: &[&dyn AsRef<OsStr>] = &[&"cargo", &"build", &"--release"];
-    run_command_with_output(cmd, Some(&Path::new("clones/rustlantis")))?;
+    run_command_with_output(cmd, Some(Path::new("clones/rustlantis")))?;
     // Fuzz a given range
     fuzz_range(start, start + count, threads);
     Ok(())
@@ -104,13 +104,13 @@ fn fuzz_range(start: u64, end: u64, threads: usize) {
                 match test(next, false) {
                     Err(err) => {
                         // If the test failed at compile-time...
-                        println!("test({}) failed because {err:?}", next);
+                        println!("test({next}) failed because {err:?}");
                         // ... copy that file to the directory `target/fuzz/compiletime_error`...
                         let mut out_path: std::path::PathBuf =
                             "target/fuzz/compiletime_error".into();
                         std::fs::create_dir_all(&out_path).unwrap();
                         // .. into a file named `fuzz{seed}.rs`.
-                        out_path.push(&format!("fuzz{next}.rs"));
+                        out_path.push(format!("fuzz{next}.rs"));
                         std::fs::copy(err, out_path).unwrap();
                     }
                     Ok(Err(err)) => {
@@ -122,12 +122,12 @@ fn fuzz_range(start: u64, end: u64, threads: usize) {
                         let Ok(Err(tmp_print_err)) = test(next, true) else {
                             // ... if that file does not reproduce the issue...
                             // ... save the original sample in a file named `fuzz{seed}.rs`...
-                            out_path.push(&format!("fuzz{next}.rs"));
+                            out_path.push(format!("fuzz{next}.rs"));
                             std::fs::copy(err, &out_path).unwrap();
                             continue;
                         };
                         // ... if that new file still produces the issue, copy it to `fuzz{seed}.rs`..
-                        out_path.push(&format!("fuzz{next}.rs"));
+                        out_path.push(format!("fuzz{next}.rs"));
                         std::fs::copy(tmp_print_err, &out_path).unwrap();
                         // ... and start reducing it, using some properties of `rustlantis` to speed up the process.
                         reduce::reduce(&out_path);
@@ -240,10 +240,10 @@ fn test_cached(
     cache: &mut ResultCache,
 ) -> Result<Result<(), std::path::PathBuf>, String> {
     //  Test `source_file` with release GCC ...
-    let gcc_res = release_gcc(&source_file)?;
+    let gcc_res = release_gcc(source_file)?;
     if cache.is_none() {
         // ...test `source_file` with debug LLVM ...
-        *cache = Some((debug_llvm(&source_file)?, gcc_res.clone()));
+        *cache = Some((debug_llvm(source_file)?, gcc_res.clone()));
     }
     let (llvm_res, old_gcc) = cache.as_ref().unwrap();
     // ... compare the results ...
@@ -269,12 +269,12 @@ fn test_file(
 fn generate(seed: u64, print_tmp_vars: bool) -> Result<std::path::PathBuf, String> {
     use std::io::Write;
     let mut out_path = std::env::temp_dir();
-    out_path.push(&format!("fuzz{seed}.rs"));
+    out_path.push(format!("fuzz{seed}.rs"));
     // We need to get the command output here.
     let mut generate = std::process::Command::new("cargo");
     generate
         .args(["run", "--release", "--bin", "generate"])
-        .arg(&format!("{seed}"))
+        .arg(format!("{seed}"))
         .current_dir("clones/rustlantis");
     if print_tmp_vars {
         generate.arg("--debug");
diff --git a/build_system/src/fuzz/reduce.rs b/build_system/src/fuzz/reduce.rs
index 24d58b879ed..20715ab0e7c 100644
--- a/build_system/src/fuzz/reduce.rs
+++ b/build_system/src/fuzz/reduce.rs
@@ -4,9 +4,9 @@ use std::path::{Path, PathBuf};
 use super::ResultCache;
 
 /// Saves a reduced file for a given `stage`
-fn save_reduction(lines: &[String], path: &PathBuf, stage: &str) {
-    let mut path = path.clone();
-    path.set_extension(&format!("rs.{stage}"));
+fn save_reduction(lines: &[String], path: &Path, stage: &str) {
+    let mut path = path.to_path_buf();
+    path.set_extension(format!("rs.{stage}"));
     let mut file = std::fs::File::create(&path).expect("Could not create the reduced example file");
     for line in lines {
         file.write_all(line.as_bytes()).expect("Could not save the reduced example");
@@ -14,8 +14,8 @@ fn save_reduction(lines: &[String], path: &PathBuf, stage: &str) {
 }
 
 /// Checks if a given reduction is valid.
-fn test_reduction(lines: &[String], path: &PathBuf, cache: &mut ResultCache) -> bool {
-    let mut path = path.clone();
+fn test_reduction(lines: &[String], path: &Path, cache: &mut ResultCache) -> bool {
+    let mut path = path.to_path_buf();
     path.set_extension("rs_reduced");
     let mut file = std::fs::File::create(&path).expect("Could not create the reduced example file");
     for line in lines {
@@ -25,7 +25,7 @@ fn test_reduction(lines: &[String], path: &PathBuf, cache: &mut ResultCache) ->
     let Ok(Err(_)) = res else {
         return false;
     };
-    return true;
+    true
 }
 
 /// Removes duplicate assignments in bulk.
@@ -73,8 +73,8 @@ fn remove_dup_assign(
         return;
     }
     // Check if the removed lines affected the execution result in any way, shape or form.
-    if test_reduction(&file_copy, &path, cache) {
-        println!("Reduced {path:?} by {} lines `remove_dup_assign`", reduction_count);
+    if test_reduction(&file_copy, path, cache) {
+        println!("Reduced {path:?} by {reduction_count} lines `remove_dup_assign`");
         *file = file_copy;
     } else {
         // The execution result changed.
@@ -110,7 +110,7 @@ fn remove_dump_var(file: &mut Vec<String>, path: &PathBuf) {
         // Not cached - the execution result can change.
         let mut uncached = None;
         // Check if this reduction is valid.
-        if test_reduction(&file_copy, &path, &mut uncached) {
+        if test_reduction(&file_copy, path, &mut uncached) {
             println!("Reduced {path:?} by 3 lines `remove_dump_var`");
             *file = file_copy;
             curr = line;
@@ -160,7 +160,7 @@ fn match_to_goto(file: &mut Vec<String>, path: &PathBuf, cache: &mut ResultCache
             file_copy.remove(match_starts);
         }
         file_copy.insert(match_starts, format!("Goto(bb{bb_ident})\n"));
-        if test_reduction(&file_copy, &path, cache) {
+        if test_reduction(&file_copy, path, cache) {
             println!("Reduced {path:?} by {} lines `match_to_goto`", match_ends - match_starts);
             *file = file_copy;
             curr = match_starts;
@@ -203,11 +203,12 @@ fn block_abort(file: &mut Vec<String>, path: &PathBuf, cache: &mut ResultCache)
         // ..and insert an unconditional call to abort.
         file_copy.insert(
             block_starts,
-            format!("Call(tmp = core::intrinsics::abort(), ReturnTo(bb1), UnwindUnreachable())\n"),
+            "Call(tmp = core::intrinsics::abort(), ReturnTo(bb1), UnwindUnreachable())\n"
+                .to_string(),
         );
-        file_copy.insert(block_starts, format!("let tmp = ();\n"));
+        file_copy.insert(block_starts, "let tmp = ();\n".to_string());
 
-        if test_reduction(&file_copy, &path, cache) {
+        if test_reduction(&file_copy, path, cache) {
             println!("Reduced {path:?} by {} lines `block_abort`", block_ends - block_starts - 2);
             *file = file_copy;
             curr = block_starts;
@@ -248,7 +249,7 @@ fn remove_block(file: &mut Vec<String>, path: &PathBuf, cache: &mut ResultCache)
         }
         let mut file_copy = file.clone();
         file_copy.drain(block_starts..block_ends);
-        if test_reduction(&file_copy, &path, cache) {
+        if test_reduction(&file_copy, path, cache) {
             println!("Reduced {path:?} by {} lines `remove_blocks`", block_ends - block_starts);
             *file = file_copy;
             curr = block_starts;
@@ -295,7 +296,7 @@ fn linearize_cf(file: &mut Vec<String>, path: &PathBuf, cache: &mut ResultCache)
         file_copy.remove(block_starts - 2);
         file_copy.remove(block_starts - 2);
         // Check if this reduction is valid.
-        if test_reduction(&file_copy, &path, cache) {
+        if test_reduction(&file_copy, path, cache) {
             println!("Reduced {path:?} by 3 lines `linearize_cf`");
             *file = file_copy;
             curr = block_starts;
@@ -345,7 +346,7 @@ fn remove_fn_calls(file: &mut Vec<String>, path: &PathBuf, cache: &mut ResultCac
         file_copy.insert(fn_call, format!("Goto({block})\n"));
         file_copy.insert(fn_call, format!("{place} = 0;\n"));
         // Check if this reduction is valid.
-        if test_reduction(&file_copy, &path, cache) {
+        if test_reduction(&file_copy, path, cache) {
             println!("Reduced {path:?} using `remove_fn_calls` {cache:?}");
             *file = file_copy;
             curr = fn_call;
@@ -382,7 +383,7 @@ fn remove_fns(file: &mut Vec<String>, path: &PathBuf, cache: &mut ResultCache) {
         // Remove the function.\\
         file_copy.drain(fn_start..fn_end);
         // Check if this reduction is valid.
-        if test_reduction(&file_copy, &path, cache) {
+        if test_reduction(&file_copy, path, cache) {
             println!("Reduced {path:?} by {} lines `remove_fns`", fn_end - fn_start);
             *file = file_copy;
         } else {
diff --git a/build_system/src/info.rs b/build_system/src/info.rs
index bd891de2eb4..66fdcf88cbb 100644
--- a/build_system/src/info.rs
+++ b/build_system/src/info.rs
@@ -15,7 +15,7 @@ pub fn run() -> Result<(), String> {
     config.no_download = true;
     config.setup_gcc_path()?;
     if let Some(gcc_path) = config.gcc_path {
-        println!("{}", gcc_path);
+        println!("{gcc_path}");
     }
     Ok(())
 }
diff --git a/build_system/src/prepare.rs b/build_system/src/prepare.rs
index d14639afee5..35a6e20fb86 100644
--- a/build_system/src/prepare.rs
+++ b/build_system/src/prepare.rs
@@ -18,9 +18,9 @@ fn prepare_libcore(
     if let Some(path) = sysroot_source {
         rustlib_dir = Path::new(&path)
             .canonicalize()
-            .map_err(|error| format!("Failed to canonicalize path: {:?}", error))?;
+            .map_err(|error| format!("Failed to canonicalize path: {error:?}"))?;
         if !rustlib_dir.is_dir() {
-            return Err(format!("Custom sysroot path {:?} not found", rustlib_dir));
+            return Err(format!("Custom sysroot path {rustlib_dir:?} not found"));
         }
     } else {
         let rustc_path = match get_rustc_path() {
@@ -36,17 +36,17 @@ fn prepare_libcore(
         rustlib_dir = parent
             .join("../lib/rustlib/src/rust")
             .canonicalize()
-            .map_err(|error| format!("Failed to canonicalize path: {:?}", error))?;
+            .map_err(|error| format!("Failed to canonicalize path: {error:?}"))?;
         if !rustlib_dir.is_dir() {
             return Err("Please install `rust-src` component".to_string());
         }
     }
 
     let sysroot_dir = sysroot_path.join("sysroot_src");
-    if sysroot_dir.is_dir() {
-        if let Err(error) = fs::remove_dir_all(&sysroot_dir) {
-            return Err(format!("Failed to remove `{}`: {:?}", sysroot_dir.display(), error,));
-        }
+    if sysroot_dir.is_dir()
+        && let Err(error) = fs::remove_dir_all(&sysroot_dir)
+    {
+        return Err(format!("Failed to remove `{}`: {:?}", sysroot_dir.display(), error,));
     }
 
     let sysroot_library_dir = sysroot_dir.join("library");
@@ -122,7 +122,7 @@ fn prepare_rand() -> Result<(), String> {
     // Apply patch for the rand crate.
     let file_path = "patches/crates/0001-Remove-deny-warnings.patch";
     let rand_dir = Path::new("build/rand");
-    println!("[GIT] apply `{}`", file_path);
+    println!("[GIT] apply `{file_path}`");
     let path = Path::new("../..").join(file_path);
     run_command_with_output(&[&"git", &"apply", &path], Some(rand_dir))?;
     run_command_with_output(&[&"git", &"add", &"-A"], Some(rand_dir))?;
@@ -149,7 +149,7 @@ fn clone_and_setup<F>(repo_url: &str, checkout_commit: &str, extra: Option<F>) -
 where
     F: Fn(&Path) -> Result<(), String>,
 {
-    let clone_result = git_clone_root_dir(repo_url, &Path::new(crate::BUILD_DIR), false)?;
+    let clone_result = git_clone_root_dir(repo_url, Path::new(crate::BUILD_DIR), false)?;
     if !clone_result.ran_clone {
         println!("`{}` has already been cloned", clone_result.repo_name);
     }
diff --git a/build_system/src/rust_tools.rs b/build_system/src/rust_tools.rs
index 7e3e37a30a8..b1faa27acc4 100644
--- a/build_system/src/rust_tools.rs
+++ b/build_system/src/rust_tools.rs
@@ -9,15 +9,14 @@ use crate::utils::{get_toolchain, rustc_toolchain_version_info, rustc_version_in
 
 fn args(command: &str) -> Result<Option<Vec<String>>, String> {
     // We skip the binary and the "cargo"/"rustc" option.
-    if let Some("--help") = std::env::args().skip(2).next().as_deref() {
+    if let Some("--help") = std::env::args().nth(2).as_deref() {
         usage(command);
         return Ok(None);
     }
     let args = std::env::args().skip(2).collect::<Vec<_>>();
     if args.is_empty() {
         return Err(format!(
-            "Expected at least one argument for `{}` subcommand, found none",
-            command
+            "Expected at least one argument for `{command}` subcommand, found none"
         ));
     }
     Ok(Some(args))
@@ -26,12 +25,11 @@ fn args(command: &str) -> Result<Option<Vec<String>>, String> {
 fn usage(command: &str) {
     println!(
         r#"
-`{}` command help:
+`{command}` command help:
 
     [args]     : Arguments to be passed to the cargo command
     --help     : Show this help
 "#,
-        command,
     )
 }
 
@@ -50,10 +48,10 @@ impl RustcTools {
         // expected.
         let current_dir = std::env::current_dir()
             .and_then(|path| path.canonicalize())
-            .map_err(|error| format!("Failed to get current directory path: {:?}", error))?;
+            .map_err(|error| format!("Failed to get current directory path: {error:?}"))?;
         let current_exe = std::env::current_exe()
             .and_then(|path| path.canonicalize())
-            .map_err(|error| format!("Failed to get current exe path: {:?}", error))?;
+            .map_err(|error| format!("Failed to get current exe path: {error:?}"))?;
         let mut parent_dir =
             current_exe.components().map(|comp| comp.as_os_str()).collect::<Vec<_>>();
         // We run this script from "build_system/target/release/y", so we need to remove these elements.
@@ -67,7 +65,7 @@ impl RustcTools {
                 ));
             }
         }
-        let parent_dir = PathBuf::from(parent_dir.join(&OsStr::new("/")));
+        let parent_dir = PathBuf::from(parent_dir.join(OsStr::new("/")));
         std::env::set_current_dir(&parent_dir).map_err(|error| {
             format!("Failed to go to `{}` folder: {:?}", parent_dir.display(), error)
         })?;
@@ -91,7 +89,7 @@ impl RustcTools {
         std::env::set_current_dir(&current_dir).map_err(|error| {
             format!("Failed to go back to `{}` folder: {:?}", current_dir.display(), error)
         })?;
-        let toolchain = format!("+{}", toolchain);
+        let toolchain = format!("+{toolchain}");
         Ok(Some(Self { toolchain, args, env, config }))
     }
 }
diff --git a/build_system/src/test.rs b/build_system/src/test.rs
index 515303a67be..bcaab0fb526 100644
--- a/build_system/src/test.rs
+++ b/build_system/src/test.rs
@@ -53,9 +53,9 @@ fn get_number_after_arg(
     match args.next() {
         Some(nb) if !nb.is_empty() => match usize::from_str(&nb) {
             Ok(nb) => Ok(nb),
-            Err(_) => Err(format!("Expected a number after `{}`, found `{}`", option, nb)),
+            Err(_) => Err(format!("Expected a number after `{option}`, found `{nb}`")),
         },
-        _ => Err(format!("Expected a number after `{}`, found nothing", option)),
+        _ => Err(format!("Expected a number after `{option}`, found nothing")),
     }
 }
 
@@ -76,8 +76,8 @@ fn show_usage() {
     for (option, (doc, _)) in get_runners() {
         // FIXME: Instead of using the hard-coded `23` value, better to compute it instead.
         let needed_spaces = 23_usize.saturating_sub(option.len());
-        let spaces: String = std::iter::repeat(' ').take(needed_spaces).collect();
-        println!("    {}{}: {}", option, spaces, doc);
+        let spaces: String = std::iter::repeat_n(' ', needed_spaces).collect();
+        println!("    {option}{spaces}: {doc}");
     }
     println!("    --help                 : Show this help");
 }
@@ -139,7 +139,7 @@ impl TestArg {
                         test_arg.sysroot_features.push(feature);
                     }
                     _ => {
-                        return Err(format!("Expected an argument after `{}`, found nothing", arg));
+                        return Err(format!("Expected an argument after `{arg}`, found nothing"));
                     }
                 },
                 "--help" => {
@@ -154,7 +154,7 @@ impl TestArg {
                 }
                 arg => {
                     if !test_arg.config_info.parse_argument(arg, &mut args)? {
-                        return Err(format!("Unknown option {}", arg));
+                        return Err(format!("Unknown option {arg}"));
                     }
                 }
             }
@@ -192,7 +192,7 @@ fn build_if_no_backend(env: &Env, args: &TestArg) -> Result<(), String> {
         command.push(&"--release");
         &tmp_env
     } else {
-        &env
+        env
     };
     for flag in args.flags.iter() {
         command.push(flag);
@@ -252,7 +252,7 @@ fn mini_tests(env: &Env, args: &TestArg) -> Result<(), String> {
         &"--target",
         &args.config_info.target_triple,
     ]);
-    run_command_with_output_and_env(&command, None, Some(&env))?;
+    run_command_with_output_and_env(&command, None, Some(env))?;
 
     // FIXME: create a function "display_if_not_quiet" or something along the line.
     println!("[BUILD] example");
@@ -264,7 +264,7 @@ fn mini_tests(env: &Env, args: &TestArg) -> Result<(), String> {
         &"--target",
         &args.config_info.target_triple,
     ]);
-    run_command_with_output_and_env(&command, None, Some(&env))?;
+    run_command_with_output_and_env(&command, None, Some(env))?;
 
     // FIXME: create a function "display_if_not_quiet" or something along the line.
     println!("[AOT] mini_core_hello_world");
@@ -279,14 +279,14 @@ fn mini_tests(env: &Env, args: &TestArg) -> Result<(), String> {
         &"--target",
         &args.config_info.target_triple,
     ]);
-    run_command_with_output_and_env(&command, None, Some(&env))?;
+    run_command_with_output_and_env(&command, None, Some(env))?;
 
     let command: &[&dyn AsRef<OsStr>] = &[
         &Path::new(&args.config_info.cargo_target_dir).join("mini_core_hello_world"),
         &"abc",
         &"bcd",
     ];
-    maybe_run_command_in_vm(&command, env, args)?;
+    maybe_run_command_in_vm(command, env, args)?;
     Ok(())
 }
 
@@ -512,19 +512,19 @@ fn setup_rustc(env: &mut Env, args: &TestArg) -> Result<PathBuf, String> {
     let cargo = String::from_utf8(
         run_command_with_env(&[&"rustup", &"which", &"cargo"], rust_dir, Some(env))?.stdout,
     )
-    .map_err(|error| format!("Failed to retrieve cargo path: {:?}", error))
+    .map_err(|error| format!("Failed to retrieve cargo path: {error:?}"))
     .and_then(|cargo| {
         let cargo = cargo.trim().to_owned();
-        if cargo.is_empty() { Err(format!("`cargo` path is empty")) } else { Ok(cargo) }
+        if cargo.is_empty() { Err("`cargo` path is empty".to_string()) } else { Ok(cargo) }
     })?;
     let rustc = String::from_utf8(
         run_command_with_env(&[&"rustup", &toolchain, &"which", &"rustc"], rust_dir, Some(env))?
             .stdout,
     )
-    .map_err(|error| format!("Failed to retrieve rustc path: {:?}", error))
+    .map_err(|error| format!("Failed to retrieve rustc path: {error:?}"))
     .and_then(|rustc| {
         let rustc = rustc.trim().to_owned();
-        if rustc.is_empty() { Err(format!("`rustc` path is empty")) } else { Ok(rustc) }
+        if rustc.is_empty() { Err("`rustc` path is empty".to_string()) } else { Ok(rustc) }
     })?;
     let llvm_filecheck = match run_command_with_env(
         &[
@@ -551,7 +551,7 @@ fn setup_rustc(env: &mut Env, args: &TestArg) -> Result<PathBuf, String> {
     let file_path = rust_dir_path.join("config.toml");
     std::fs::write(
         &file_path,
-        &format!(
+        format!(
             r#"change-id = 115898
 
 [rust]
@@ -590,7 +590,7 @@ fn asm_tests(env: &Env, args: &TestArg) -> Result<(), String> {
     let codegen_backend_path = format!(
         "{pwd}/target/{channel}/librustc_codegen_gcc.{dylib_ext}",
         pwd = std::env::current_dir()
-            .map_err(|error| format!("`current_dir` failed: {:?}", error))?
+            .map_err(|error| format!("`current_dir` failed: {error:?}"))?
             .display(),
         channel = args.config_info.channel.as_str(),
         dylib_ext = args.config_info.dylib_ext,
@@ -645,11 +645,11 @@ where
     F: Fn(&[&dyn AsRef<OsStr>], Option<&Path>, &Env) -> Result<(), String>,
 {
     let toolchain = get_toolchain()?;
-    let toolchain_arg = format!("+{}", toolchain);
+    let toolchain_arg = format!("+{toolchain}");
     let rustc_version = String::from_utf8(
         run_command_with_env(&[&args.config_info.rustc_command[0], &"-V"], cwd, Some(env))?.stdout,
     )
-    .map_err(|error| format!("Failed to retrieve rustc version: {:?}", error))?;
+    .map_err(|error| format!("Failed to retrieve rustc version: {error:?}"))?;
     let rustc_toolchain_version = String::from_utf8(
         run_command_with_env(
             &[&args.config_info.rustc_command[0], &toolchain_arg, &"-V"],
@@ -658,20 +658,19 @@ where
         )?
         .stdout,
     )
-    .map_err(|error| format!("Failed to retrieve rustc +toolchain version: {:?}", error))?;
+    .map_err(|error| format!("Failed to retrieve rustc +toolchain version: {error:?}"))?;
 
     if rustc_version != rustc_toolchain_version {
         eprintln!(
-            "rustc_codegen_gcc is built for `{}` but the default rustc version is `{}`.",
-            rustc_toolchain_version, rustc_version,
+            "rustc_codegen_gcc is built for `{rustc_toolchain_version}` but the default rustc version is `{rustc_version}`.",
         );
-        eprintln!("Using `{}`.", rustc_toolchain_version);
+        eprintln!("Using `{rustc_toolchain_version}`.");
     }
     let mut env = env.clone();
     let rustflags = env.get("RUSTFLAGS").cloned().unwrap_or_default();
     env.insert("RUSTDOCFLAGS".to_string(), rustflags);
     let mut cargo_command: Vec<&dyn AsRef<OsStr>> = vec![&"cargo", &toolchain_arg];
-    cargo_command.extend_from_slice(&command);
+    cargo_command.extend_from_slice(command);
     callback(&cargo_command, cwd, &env)
 }
 
@@ -884,7 +883,7 @@ fn contains_ui_error_patterns(file_path: &Path, keep_lto_tests: bool) -> Result<
     // Tests generating errors.
     let file = File::open(file_path)
         .map_err(|error| format!("Failed to read `{}`: {:?}", file_path.display(), error))?;
-    for line in BufReader::new(file).lines().filter_map(|line| line.ok()) {
+    for line in BufReader::new(file).lines().map_while(Result::ok) {
         let line = line.trim();
         if line.is_empty() {
             continue;
@@ -953,7 +952,7 @@ where
 
     if !prepare_files_callback(&rust_path)? {
         // FIXME: create a function "display_if_not_quiet" or something along the line.
-        println!("Keeping all {} tests", test_type);
+        println!("Keeping all {test_type} tests");
     }
 
     if test_type == "ui" {
@@ -985,8 +984,7 @@ where
                         "borrowck",
                         "test-attrs",
                     ]
-                    .iter()
-                    .any(|name| *name == dir_name)
+                    .contains(&dir_name)
                     {
                         remove_dir_all(dir).map_err(|error| {
                             format!("Failed to remove folder `{}`: {:?}", dir.display(), error)
@@ -1041,10 +1039,7 @@ where
         if nb_parts > 0 {
             let current_part = args.current_part.unwrap();
             // FIXME: create a function "display_if_not_quiet" or something along the line.
-            println!(
-                "Splitting ui_test into {} parts (and running part {})",
-                nb_parts, current_part
-            );
+            println!("Splitting ui_test into {nb_parts} parts (and running part {current_part})");
             let out = String::from_utf8(
                 run_command(
                     &[
@@ -1062,7 +1057,7 @@ where
                 )?
                 .stdout,
             )
-            .map_err(|error| format!("Failed to retrieve output of find command: {:?}", error))?;
+            .map_err(|error| format!("Failed to retrieve output of find command: {error:?}"))?;
             let mut files = out
                 .split('\n')
                 .map(|line| line.trim())
@@ -1082,7 +1077,7 @@ where
     }
 
     // FIXME: create a function "display_if_not_quiet" or something along the line.
-    println!("[TEST] rustc {} test suite", test_type);
+    println!("[TEST] rustc {test_type} test suite");
     env.insert("COMPILETEST_FORCE_STAGE0".to_string(), "1".to_string());
 
     let extra =
@@ -1106,7 +1101,7 @@ where
             &"always",
             &"--stage",
             &"0",
-            &format!("tests/{}", test_type),
+            &format!("tests/{test_type}"),
             &"--compiletest-rustc-args",
             &rustc_args,
         ],
@@ -1182,7 +1177,7 @@ fn retain_files_callback<'a>(
             run_command(
                 &[
                     &"find",
-                    &format!("tests/{}", test_type),
+                    &format!("tests/{test_type}"),
                     &"-mindepth",
                     &"1",
                     &"-type",
@@ -1201,7 +1196,7 @@ fn retain_files_callback<'a>(
             run_command(
                 &[
                     &"find",
-                    &format!("tests/{}", test_type),
+                    &format!("tests/{test_type}"),
                     &"-type",
                     &"f",
                     &"-name",
@@ -1216,15 +1211,12 @@ fn retain_files_callback<'a>(
         }
 
         // Putting back only the failing ones.
-        if let Ok(files) = std::fs::read_to_string(&file_path) {
+        if let Ok(files) = std::fs::read_to_string(file_path) {
             for file in files.split('\n').map(|line| line.trim()).filter(|line| !line.is_empty()) {
-                run_command(&[&"git", &"checkout", &"--", &file], Some(&rust_path))?;
+                run_command(&[&"git", &"checkout", &"--", &file], Some(rust_path))?;
             }
         } else {
-            println!(
-                "Failed to read `{}`, not putting back failing {} tests",
-                file_path, test_type
-            );
+            println!("Failed to read `{file_path}`, not putting back failing {test_type} tests");
         }
 
         Ok(true)
@@ -1252,8 +1244,7 @@ fn remove_files_callback<'a>(
                 }
             } else {
                 println!(
-                    "Failed to read `{}`, not putting back failing {} tests",
-                    file_path, test_type
+                    "Failed to read `{file_path}`, not putting back failing {test_type} tests"
                 );
             }
         } else {
@@ -1266,7 +1257,7 @@ fn remove_files_callback<'a>(
                     remove_file(&path)?;
                 }
             } else {
-                println!("Failed to read `{}`, not putting back failing ui tests", file_path);
+                println!("Failed to read `{file_path}`, not putting back failing ui tests");
             }
         }
         Ok(true)
diff --git a/build_system/src/utils.rs b/build_system/src/utils.rs
index da91b3a8c29..d77707d5f17 100644
--- a/build_system/src/utils.rs
+++ b/build_system/src/utils.rs
@@ -21,7 +21,7 @@ fn exec_command(
     {
         if let Some(signal) = status.signal() {
             // In case the signal didn't kill the current process.
-            return Err(command_error(input, &cwd, format!("Process received signal {}", signal)));
+            return Err(command_error(input, &cwd, format!("Process received signal {signal}")));
         }
     }
     Ok(status)
@@ -65,18 +65,18 @@ fn check_exit_status(
     );
     let input = input.iter().map(|i| i.as_ref()).collect::<Vec<&OsStr>>();
     if show_err {
-        eprintln!("Command `{:?}` failed", input);
+        eprintln!("Command `{input:?}` failed");
     }
     if let Some(output) = output {
         let stdout = String::from_utf8_lossy(&output.stdout);
         if !stdout.is_empty() {
             error.push_str("\n==== STDOUT ====\n");
-            error.push_str(&*stdout);
+            error.push_str(&stdout);
         }
         let stderr = String::from_utf8_lossy(&output.stderr);
         if !stderr.is_empty() {
             error.push_str("\n==== STDERR ====\n");
-            error.push_str(&*stderr);
+            error.push_str(&stderr);
         }
     }
     Err(error)
@@ -233,7 +233,7 @@ pub fn get_toolchain() -> Result<String, String> {
             if !line.starts_with("channel") {
                 return None;
             }
-            line.split('"').skip(1).next()
+            line.split('"').nth(1)
         })
         .next()
     {
@@ -272,7 +272,7 @@ fn git_clone_inner(
 }
 
 fn get_repo_name(url: &str) -> String {
-    let repo_name = url.split('/').last().unwrap();
+    let repo_name = url.split('/').next_back().unwrap();
     match repo_name.strip_suffix(".git") {
         Some(n) => n.to_string(),
         None => repo_name.to_string(),
diff --git a/src/intrinsic/llvm.rs b/src/intrinsic/llvm.rs
index 97b94428187..0b77694f115 100644
--- a/src/intrinsic/llvm.rs
+++ b/src/intrinsic/llvm.rs
@@ -1012,7 +1012,7 @@ pub fn intrinsic<'gcc, 'tcx>(name: &str, cx: &CodegenCx<'gcc, 'tcx>) -> Function
     };
     let func = cx.context.get_builtin_function(gcc_name);
     cx.functions.borrow_mut().insert(gcc_name.to_string(), func);
-    return func;
+    func
 }
 
 #[cfg(feature = "master")]
diff --git a/src/type_.rs b/src/type_.rs
index 4e0a250b550..15a0206607e 100644
--- a/src/type_.rs
+++ b/src/type_.rs
@@ -302,13 +302,13 @@ impl<'gcc, 'tcx> BaseTypeCodegenMethods for CodegenCx<'gcc, 'tcx> {
     #[cfg_attr(feature = "master", allow(unused_mut))]
     fn type_array(&self, ty: Type<'gcc>, mut len: u64) -> Type<'gcc> {
         #[cfg(not(feature = "master"))]
-        if let Some(struct_type) = ty.is_struct() {
-            if struct_type.get_field_count() == 0 {
-                // NOTE: since gccjit only supports i32 for the array size and libcore's tests uses a
-                // size of usize::MAX in test_binary_search, we workaround this by setting the size to
-                // zero for ZSTs.
-                len = 0;
-            }
+        if let Some(struct_type) = ty.is_struct()
+            && struct_type.get_field_count() == 0
+        {
+            // NOTE: since gccjit only supports i32 for the array size and libcore's tests uses a
+            // size of usize::MAX in test_binary_search, we workaround this by setting the size to
+            // zero for ZSTs.
+            len = 0;
         }
 
         self.context.new_array_type(None, ty, len)
diff --git a/tests/lang_tests_common.rs b/tests/lang_tests_common.rs
index bdcf14b4b26..9abe97b1087 100644
--- a/tests/lang_tests_common.rs
+++ b/tests/lang_tests_common.rs
@@ -57,10 +57,10 @@ pub fn main_inner(profile: Profile) {
 
     #[cfg(not(feature = "master"))]
     fn filter(filename: &Path) -> bool {
-        if let Some(filename) = filename.to_str() {
-            if filename.ends_with("gep.rs") {
-                return false;
-            }
+        if let Some(filename) = filename.to_str()
+            && filename.ends_with("gep.rs")
+        {
+            return false;
         }
         rust_filter(filename)
     }