some cleanups in compiler

compiler/rustc_arena/src/tests.rs

@@ -19,8 +19,8 @@ impl<T> TypedArena<T> {
         unsafe {
             // Clear the last chunk, which is partially filled.
             let mut chunks_borrow = self.chunks.borrow_mut();
-            if let Some(mut last_chunk) = chunks_borrow.last_mut() {
-                self.clear_last_chunk(&mut last_chunk);
+            if let Some(last_chunk) = chunks_borrow.last_mut() {
+                self.clear_last_chunk(last_chunk);
                 let len = chunks_borrow.len();
                 // If `T` is ZST, code below has no effect.
                 for mut chunk in chunks_borrow.drain(..len - 1) {

compiler/rustc_fluent_macro/src/fluent.rs

@@ -265,7 +265,7 @@ pub(crate) fn fluent_messages(input: proc_macro::TokenStream) -> proc_macro::Tok
                 Level::Error,
                 format!("referenced message `{mref}` does not exist (in message `{name}`)"),
             )
-            .help(&format!("you may have meant to use a variable reference (`{{${mref}}}`)"))
+            .help(format!("you may have meant to use a variable reference (`{{${mref}}}`)"))
             .emit();
         }
     }

compiler/rustc_graphviz/src/tests.rs

@@ -63,10 +63,10 @@ impl NodeLabels<&'static str> {
     }
 
     fn len(&self) -> usize {
-        match self {
-            &UnlabelledNodes(len) => len,
-            &AllNodesLabelled(ref lbls) => lbls.len(),
-            &SomeNodesLabelled(ref lbls) => lbls.len(),
+        match *self {
+            UnlabelledNodes(len) => len,
+            AllNodesLabelled(ref lbls) => lbls.len(),
+            SomeNodesLabelled(ref lbls) => lbls.len(),
         }
     }
 }

compiler/rustc_hashes/src/lib.rs

@@ -54,7 +54,7 @@ impl FromStableHash for Hash64 {
     type Hash = StableHasherHash;
 
     #[inline]
-    fn from(StableHasherHash([_0, __1]): Self::Hash) -> Self {
+    fn from(StableHasherHash([_0, _]): Self::Hash) -> Self {
         Self { inner: _0 }
     }
 }

compiler/rustc_llvm/build.rs

@@ -197,7 +197,7 @@ fn main() {
 
         // Include path contains host directory, replace it with target
         if is_crossed && flag.starts_with("-I") {
-            cfg.flag(&flag.replace(&host, &target));
+            cfg.flag(flag.replace(&host, &target));
             continue;
         }
 

compiler/rustc_log/src/lib.rs

@@ -73,7 +73,7 @@ impl LoggerConfig {
 
 /// Initialize the logger with the given values for the filter, coloring, and other options env variables.
 pub fn init_logger(cfg: LoggerConfig) -> Result<(), Error> {
-    init_logger_with_additional_layer(cfg, || Registry::default())
+    init_logger_with_additional_layer(cfg, Registry::default)
 }
 
 /// Trait alias for the complex return type of `build_subscriber` in
@@ -145,14 +145,11 @@ where
         .with_thread_ids(verbose_thread_ids)
         .with_thread_names(verbose_thread_ids);
 
-    match cfg.wraptree {
-        Ok(v) => match v.parse::<usize>() {
-            Ok(v) => {
-                layer = layer.with_wraparound(v);
-            }
+    if let Ok(v) = cfg.wraptree {
+        match v.parse::<usize>() {
+            Ok(v) => layer = layer.with_wraparound(v),
             Err(_) => return Err(Error::InvalidWraptree(v)),
-        },
-        Err(_) => {} // no wraptree
+        }
     }
 
     let subscriber = build_subscriber().with(layer.with_filter(filter));

compiler/rustc_thread_pool/src/registry.rs

@@ -808,7 +808,7 @@ impl WorkerThread {
         latch: &L,
         mut all_jobs_started: impl FnMut() -> bool,
         mut is_job: impl FnMut(&JobRef) -> bool,
-        mut execute_job: impl FnMut(JobRef) -> (),
+        mut execute_job: impl FnMut(JobRef),
     ) {
         let mut jobs = SmallVec::<[JobRef; 8]>::new();
         let mut broadcast_jobs = SmallVec::<[JobRef; 8]>::new();

compiler/rustc_thread_pool/src/scope/tests.rs

@@ -168,7 +168,7 @@ fn the_final_countdown<'scope>(
     let top_of_stack = 0;
     let p = bottom_of_stack as *const i32 as usize;
     let q = &top_of_stack as *const i32 as usize;
-    let diff = if p > q { p - q } else { q - p };
+    let diff = p.abs_diff(q);
 
     let mut data = max.lock().unwrap();
     *data = Ord::max(diff, *data);

compiler/rustc_thread_pool/src/thread_pool/tests.rs

@@ -97,7 +97,7 @@ fn failed_thread_stack() {
     // macOS and Windows weren't fazed, or at least didn't fail the way we want.
     // They work with `isize::MAX`, but 32-bit platforms may feasibly allocate a
     // 2GB stack, so it might not fail until the second thread.
-    let stack_size = ::std::isize::MAX as usize;
+    let stack_size = isize::MAX as usize;
 
     let (start_count, start_handler) = count_handler();
     let (exit_count, exit_handler) = count_handler();

compiler/rustc_thread_pool/src/worker_local.rs

@@ -43,7 +43,7 @@ impl<T> WorkerLocal<T> {
         unsafe {
             let worker_thread = WorkerThread::current();
             if worker_thread.is_null()
-                || &*(*worker_thread).registry as *const _ != &*self.registry as *const _
+                || !std::ptr::eq(&*(*worker_thread).registry, &*self.registry)
             {
                 panic!("WorkerLocal can only be used on the thread pool it was created on")
             }
@@ -55,7 +55,7 @@ impl<T> WorkerLocal<T> {
 impl<T> WorkerLocal<Vec<T>> {
     /// Joins the elements of all the worker locals into one Vec
     pub fn join(self) -> Vec<T> {
-        self.into_inner().into_iter().flat_map(|v| v).collect()
+        self.into_inner().into_iter().flatten().collect()
     }
 }
 

compiler/rustc_type_ir_macros/src/lib.rs

@@ -197,12 +197,12 @@ fn lift(mut ty: syn::Type) -> syn::Type {
     impl VisitMut for ItoJ {
         fn visit_type_path_mut(&mut self, i: &mut syn::TypePath) {
             if i.qself.is_none() {
-                if let Some(first) = i.path.segments.first_mut() {
-                    if first.ident == "I" {
+                if let Some(first) = i.path.segments.first_mut()
+                    && first.ident == "I"
+                {
                     *first = parse_quote! { J };
                 }
             }
-            }
             syn::visit_mut::visit_type_path_mut(self, i);
         }
     }