use expect instead of allow

This is more useful than `allow` as compiler will force us to remove rules
that are no longer valid (we already got 2 of them in this change).

Signed-off-by: onur-ozkan <work@onurozkan.dev>

src/bootstrap/src/core/build_steps/compile.rs

@@ -67,7 +67,7 @@ impl Std {
         self
     }
 
-    #[allow(clippy::wrong_self_convention)]
+    #[expect(clippy::wrong_self_convention)]
     pub fn is_for_mir_opt_tests(mut self, is_for_mir_opt_tests: bool) -> Self {
         self.is_for_mir_opt_tests = is_for_mir_opt_tests;
         self

src/bootstrap/src/core/build_steps/suggest.rs

@@ -1,7 +1,5 @@
 //! Attempt to magically identify good tests to run
 
-#![cfg_attr(feature = "build-metrics", allow(unused))]
-
 use std::path::PathBuf;
 use std::str::FromStr;
 

src/bootstrap/src/core/build_steps/test.rs

@@ -3377,7 +3377,7 @@ impl Step for CodegenCranelift {
         /*
         let mut prepare_cargo = build_cargo();
         prepare_cargo.arg("--").arg("prepare").arg("--download-dir").arg(&download_dir);
-        #[allow(deprecated)]
+        #[expect(deprecated)]
         builder.config.try_run(&mut prepare_cargo.into()).unwrap();
         */
 
@@ -3508,7 +3508,7 @@ impl Step for CodegenGCC {
         /*
         let mut prepare_cargo = build_cargo();
         prepare_cargo.arg("--").arg("prepare");
-        #[allow(deprecated)]
+        #[expect(deprecated)]
         builder.config.try_run(&mut prepare_cargo.into()).unwrap();
         */
 

src/bootstrap/src/core/build_steps/tool.rs

@@ -209,7 +209,7 @@ impl Step for ToolBuild {
     }
 }
 
-#[allow(clippy::too_many_arguments)] // FIXME: reduce the number of args and remove this.
+#[expect(clippy::too_many_arguments)] // FIXME: reduce the number of args and remove this.
 pub fn prepare_tool_cargo(
     builder: &Builder<'_>,
     compiler: Compiler,
@@ -1025,7 +1025,7 @@ pub struct LibcxxVersionTool {
     pub target: TargetSelection,
 }
 
-#[allow(dead_code)]
+#[expect(dead_code)]
 #[derive(Debug, Clone)]
 pub enum LibcxxVersion {
     Gnu(usize),

src/bootstrap/src/core/builder/mod.rs

@@ -1289,7 +1289,6 @@ impl<'a> Builder<'a> {
         host: TargetSelection,
         target: TargetSelection,
     ) -> Compiler {
-        #![allow(clippy::let_and_return)]
         let mut resolved_compiler = if self.build.force_use_stage2(stage) {
             trace!(target: "COMPILER_FOR", ?stage, "force_use_stage2");
             self.compiler(2, self.config.build)

src/bootstrap/src/core/config/mod.rs

@@ -1,4 +1,4 @@
-#[allow(clippy::module_inception)]
+#[expect(clippy::module_inception)]
 mod config;
 pub mod flags;
 #[cfg(test)]

src/bootstrap/src/core/download.rs

@@ -19,7 +19,7 @@ static SHOULD_FIX_BINS_AND_DYLIBS: OnceLock<bool> = OnceLock::new();
 
 /// `Config::try_run` wrapper for this module to avoid warnings on `try_run`, since we don't have access to a `builder` yet.
 fn try_run(config: &Config, cmd: &mut Command) -> Result<(), ()> {
-    #[allow(deprecated)]
+    #[expect(deprecated)]
     config.try_run(cmd)
 }
 

src/bootstrap/src/lib.rs

@@ -74,7 +74,7 @@ const LLD_FILE_NAMES: &[&str] = &["ld.lld", "ld64.lld", "lld-link", "wasm-ld"];
 
 /// Extra `--check-cfg` to add when building the compiler or tools
 /// (Mode restriction, config name, config values (if any))
-#[allow(clippy::type_complexity)] // It's fine for hard-coded list and type is explained above.
+#[expect(clippy::type_complexity)] // It's fine for hard-coded list and type is explained above.
 const EXTRA_CHECK_CFGS: &[(Option<Mode>, &str, Option<&[&'static str]>)] = &[
     (None, "bootstrap", None),
     (Some(Mode::Rustc), "llvm_enzyme", None),

src/bootstrap/src/utils/exec.rs

@@ -125,7 +125,7 @@ impl BootstrapCommand {
         Self { failure_behavior: BehaviorOnFailure::DelayFail, ..self }
     }
 
-    #[allow(dead_code)]
+    #[expect(dead_code)]
     pub fn fail_fast(self) -> Self {
         Self { failure_behavior: BehaviorOnFailure::Exit, ..self }
     }
@@ -280,7 +280,7 @@ impl CommandOutput {
         !self.is_success()
     }
 
-    #[allow(dead_code)]
+    #[expect(dead_code)]
     pub fn status(&self) -> Option<ExitStatus> {
         match self.status {
             CommandStatus::Finished(status) => Some(status),
@@ -332,7 +332,6 @@ impl Default for CommandOutput {
 
 /// Helper trait to format both Command and BootstrapCommand as a short execution line,
 /// without all the other details (e.g. environment variables).
-#[allow(unused)]
 pub trait FormatShortCmd {
     fn format_short_cmd(&self) -> String;
 }

src/bootstrap/src/utils/metrics.rs

@@ -76,7 +76,7 @@ impl BuildMetrics {
 
         // Consider all the stats gathered so far as the parent's.
         if !state.running_steps.is_empty() {
-            self.collect_stats(&mut *state);
+            self.collect_stats(&mut state);
         }
 
         state.system_info.refresh_cpu_usage();
@@ -102,7 +102,7 @@ impl BuildMetrics {
 
         let mut state = self.state.borrow_mut();
 
-        self.collect_stats(&mut *state);
+        self.collect_stats(&mut state);
 
         let step = state.running_steps.pop().unwrap();
         if state.running_steps.is_empty() {
@@ -224,6 +224,7 @@ impl BuildMetrics {
         t!(serde_json::to_writer(&mut file, &json));
     }
 
+    #[expect(clippy::only_used_in_recursion)]
     fn prepare_json_step(&self, step: StepMetrics) -> JsonNode {
         let mut children = Vec::new();
         children.extend(step.children.into_iter().map(|child| self.prepare_json_step(child)));