Some clippy fixes in the compiler

compiler/rustc_abi/src/lib.rs

@@ -1176,7 +1176,7 @@ impl FieldsShape {
 
     /// Gets source indices of the fields by increasing offsets.
     #[inline]
-    pub fn index_by_increasing_offset<'a>(&'a self) -> impl Iterator<Item = usize> + 'a {
+    pub fn index_by_increasing_offset(&self) -> impl Iterator<Item = usize> + '_ {
         let mut inverse_small = [0u8; 64];
         let mut inverse_big = IndexVec::new();
         let use_small = self.count() <= inverse_small.len();

compiler/rustc_arena/src/lib.rs

@@ -22,6 +22,7 @@
 #![feature(strict_provenance)]
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]
+#![allow(clippy::mut_from_ref)] // Arena allocators are one of the places where this pattern is fine.
 
 use smallvec::SmallVec;
 
@@ -568,7 +569,9 @@ pub macro declare_arena([$($a:tt $name:ident: $ty:ty,)*]) {
     }
 
     pub trait ArenaAllocatable<'tcx, C = rustc_arena::IsNotCopy>: Sized {
+        #[allow(clippy::mut_from_ref)]
         fn allocate_on<'a>(self, arena: &'a Arena<'tcx>) -> &'a mut Self;
+        #[allow(clippy::mut_from_ref)]
         fn allocate_from_iter<'a>(
             arena: &'a Arena<'tcx>,
             iter: impl ::std::iter::IntoIterator<Item = Self>,
@@ -578,10 +581,12 @@ pub macro declare_arena([$($a:tt $name:ident: $ty:ty,)*]) {
     // Any type that impls `Copy` can be arena-allocated in the `DroplessArena`.
     impl<'tcx, T: Copy> ArenaAllocatable<'tcx, rustc_arena::IsCopy> for T {
         #[inline]
+        #[allow(clippy::mut_from_ref)]
         fn allocate_on<'a>(self, arena: &'a Arena<'tcx>) -> &'a mut Self {
             arena.dropless.alloc(self)
         }
         #[inline]
+        #[allow(clippy::mut_from_ref)]
         fn allocate_from_iter<'a>(
             arena: &'a Arena<'tcx>,
             iter: impl ::std::iter::IntoIterator<Item = Self>,
@@ -601,6 +606,7 @@ pub macro declare_arena([$($a:tt $name:ident: $ty:ty,)*]) {
             }
 
             #[inline]
+            #[allow(clippy::mut_from_ref)]
             fn allocate_from_iter<'a>(
                 arena: &'a Arena<'tcx>,
                 iter: impl ::std::iter::IntoIterator<Item = Self>,
@@ -616,19 +622,22 @@ pub macro declare_arena([$($a:tt $name:ident: $ty:ty,)*]) {
 
     impl<'tcx> Arena<'tcx> {
         #[inline]
+        #[allow(clippy::mut_from_ref)]
         pub fn alloc<T: ArenaAllocatable<'tcx, C>, C>(&self, value: T) -> &mut T {
             value.allocate_on(self)
         }
 
         // Any type that impls `Copy` can have slices be arena-allocated in the `DroplessArena`.
         #[inline]
+        #[allow(clippy::mut_from_ref)]
         pub fn alloc_slice<T: ::std::marker::Copy>(&self, value: &[T]) -> &mut [T] {
             if value.is_empty() {
                 return &mut [];
             }
             self.dropless.alloc_slice(value)
         }
 
+        #[allow(clippy::mut_from_ref)]
         pub fn alloc_from_iter<'a, T: ArenaAllocatable<'tcx, C>, C>(
             &'a self,
             iter: impl ::std::iter::IntoIterator<Item = T>,

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -691,7 +691,7 @@ fn validate_generic_param_order(
                 GenericParamKind::Lifetime => (),
                 GenericParamKind::Const { ty: _, kw_span: _, default: Some(default) } => {
                     ordered_params += " = ";
-                    ordered_params += &pprust::expr_to_string(&*default.value);
+                    ordered_params += &pprust::expr_to_string(&default.value);
                 }
                 GenericParamKind::Const { ty: _, kw_span: _, default: None } => (),
             }

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -404,11 +404,14 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                     );
                 } else {
                     // And if it isn't, cancel the early-pass warning.
-                    self.sess
+                    if let Some(err) = self
+                        .sess
                         .parse_sess
                         .span_diagnostic
                         .steal_diagnostic(e.span, StashKey::EarlySyntaxWarning)
-                        .map(|err| err.cancel());
+                    {
+                        err.cancel()
+                    }
                 }
             }
             ast::ExprKind::TryBlock(_) => {

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -686,7 +686,7 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
     fn bclose_maybe_open(&mut self, span: rustc_span::Span, empty: bool, close_box: bool) {
         let has_comment = self.maybe_print_comment(span.hi());
         if !empty || has_comment {
-            self.break_offset_if_not_bol(1, -(INDENT_UNIT as isize));
+            self.break_offset_if_not_bol(1, -INDENT_UNIT);
         }
         self.word("}");
         if close_box {
@@ -988,7 +988,9 @@ impl<'a> State<'a> {
 
     pub fn print_assoc_constraint(&mut self, constraint: &ast::AssocConstraint) {
         self.print_ident(constraint.ident);
-        constraint.gen_args.as_ref().map(|args| self.print_generic_args(args, false));
+        if let Some(args) = constraint.gen_args.as_ref() {
+            self.print_generic_args(args, false)
+        }
         self.space();
         match &constraint.kind {
             ast::AssocConstraintKind::Equality { term } => {

compiler/rustc_data_structures/src/graph/implementation/mod.rs

@@ -206,17 +206,11 @@ impl<N: Debug, E: Debug> Graph<N, E> {
         AdjacentEdges { graph: self, direction, next: first_edge }
     }
 
-    pub fn successor_nodes<'a>(
-        &'a self,
-        source: NodeIndex,
-    ) -> impl Iterator<Item = NodeIndex> + 'a {
+    pub fn successor_nodes(&self, source: NodeIndex) -> impl Iterator<Item = NodeIndex> + '_ {
         self.outgoing_edges(source).targets()
     }
 
-    pub fn predecessor_nodes<'a>(
-        &'a self,
-        target: NodeIndex,
-    ) -> impl Iterator<Item = NodeIndex> + 'a {
+    pub fn predecessor_nodes(&self, target: NodeIndex) -> impl Iterator<Item = NodeIndex> + '_ {
         self.incoming_edges(target).sources()
     }
 

compiler/rustc_data_structures/src/memmap.rs

@@ -40,7 +40,7 @@ impl Deref for Mmap {
 
 impl AsRef<[u8]> for Mmap {
     fn as_ref(&self) -> &[u8] {
-        &*self.0
+        &self.0
     }
 }
 

compiler/rustc_data_structures/src/profiling.rs

@@ -778,7 +778,7 @@ pub fn print_time_passes_entry(
                 "rss_start": start_rss,
                 "rss_end": end_rss,
             });
-            eprintln!("time: {}", json.to_string());
+            eprintln!("time: {json}");
             return;
         }
         TimePassesFormat::Text => (),

compiler/rustc_data_structures/src/sharded.rs

@@ -140,6 +140,7 @@ pub fn make_hash<K: Hash + ?Sized>(val: &K) -> u64 {
 /// `hash` can be computed with any hasher, so long as that hasher is used
 /// consistently for each `Sharded` instance.
 #[inline]
+#[allow(clippy::modulo_one)]
 pub fn get_shard_index_by_hash(hash: u64) -> usize {
     let hash_len = mem::size_of::<usize>();
     // Ignore the top 7 bits as hashbrown uses these and get the next SHARD_BITS highest bits.

compiler/rustc_data_structures/src/stable_hasher.rs

@@ -312,14 +312,14 @@ impl<CTX> HashStable<CTX> for ::std::num::NonZeroUsize {
 
 impl<CTX> HashStable<CTX> for f32 {
     fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
-        let val: u32 = unsafe { ::std::mem::transmute(*self) };
+        let val: u32 = self.to_bits();
         val.hash_stable(ctx, hasher);
     }
 }
 
 impl<CTX> HashStable<CTX> for f64 {
     fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
-        let val: u64 = unsafe { ::std::mem::transmute(*self) };
+        let val: u64 = self.to_bits();
         val.hash_stable(ctx, hasher);
     }
 }

compiler/rustc_data_structures/src/stack.rs

@@ -5,7 +5,7 @@ const RED_ZONE: usize = 100 * 1024; // 100k
 
 // Only the first stack that is pushed, grows exponentially (2^n * STACK_PER_RECURSION) from then
 // on. This flag has performance relevant characteristics. Don't set it too high.
-const STACK_PER_RECURSION: usize = 1 * 1024 * 1024; // 1MB
+const STACK_PER_RECURSION: usize = 1024 * 1024; // 1MB
 
 /// Grows the stack on demand to prevent stack overflow. Call this in strategic locations
 /// to "break up" recursive calls. E.g. almost any call to `visit_expr` or equivalent can benefit

compiler/rustc_data_structures/src/sync/vec.rs

@@ -84,7 +84,7 @@ impl<T: Copy> AppendOnlyVec<T> {
     }
 
     pub fn iter(&self) -> impl Iterator<Item = T> + '_ {
-        (0..).map(|i| self.get(i)).take_while(|o| o.is_some()).filter_map(|o| o)
+        (0..).map(|i| self.get(i)).take_while(|o| o.is_some()).flatten()
     }
 }
 

compiler/rustc_data_structures/src/unord.rs

@@ -224,7 +224,7 @@ impl<V: Eq + Hash> UnordSet<V> {
     }
 
     #[inline]
-    pub fn items<'a>(&'a self) -> UnordItems<&'a V, impl Iterator<Item = &'a V>> {
+    pub fn items(&self) -> UnordItems<&V, impl Iterator<Item = &V>> {
         UnordItems(self.inner.iter())
     }
 
@@ -415,7 +415,7 @@ impl<K: Eq + Hash, V> UnordMap<K, V> {
     }
 
     #[inline]
-    pub fn items<'a>(&'a self) -> UnordItems<(&'a K, &'a V), impl Iterator<Item = (&'a K, &'a V)>> {
+    pub fn items(&self) -> UnordItems<(&K, &V), impl Iterator<Item = (&K, &V)>> {
         UnordItems(self.inner.iter())
     }
 

compiler/rustc_errors/src/diagnostic.rs

@@ -956,7 +956,7 @@ impl Diagnostic {
     // Exact iteration order of diagnostic arguments shouldn't make a difference to output because
     // they're only used in interpolation.
     #[allow(rustc::potential_query_instability)]
-    pub fn args<'a>(&'a self) -> impl Iterator<Item = DiagnosticArg<'a, 'static>> {
+    pub fn args(&self) -> impl Iterator<Item = DiagnosticArg<'_, 'static>> {
         self.args.iter()
     }
 

compiler/rustc_errors/src/emitter.rs

@@ -1407,7 +1407,7 @@ impl EmitterWriter {
                 // Account for newlines to align output to its label.
                 for (line, text) in normalize_whitespace(&text).lines().enumerate() {
                     buffer.append(
-                        0 + line,
+                        line,
                         &format!(
                             "{}{}",
                             if line == 0 { String::new() } else { " ".repeat(label_width) },
@@ -1918,7 +1918,7 @@ impl EmitterWriter {
                         let last_line = unhighlighted_lines.pop();
                         let first_line = unhighlighted_lines.drain(..).next();
 
-                        first_line.map(|(p, l)| {
+                        if let Some((p, l)) = first_line {
                             self.draw_code_line(
                                 &mut buffer,
                                 &mut row_num,
@@ -1930,12 +1930,12 @@ impl EmitterWriter {
                                 &file_lines,
                                 is_multiline,
                             )
-                        });
+                        }
 
                         buffer.puts(row_num, max_line_num_len - 1, "...", Style::LineNumber);
                         row_num += 1;
 
-                        last_line.map(|(p, l)| {
+                        if let Some((p, l)) = last_line {
                             self.draw_code_line(
                                 &mut buffer,
                                 &mut row_num,
@@ -1947,7 +1947,7 @@ impl EmitterWriter {
                                 &file_lines,
                                 is_multiline,
                             )
-                        });
+                        }
                     }
                 }
 

compiler/rustc_expand/src/config.rs

@@ -466,7 +466,7 @@ impl<'a> StripUnconfigured<'a> {
         //
         // N.B., this is intentionally not part of the visit_expr() function
         //     in order for filter_map_expr() to be able to avoid this check
-        if let Some(attr) = expr.attrs().iter().find(|a| is_cfg(*a)) {
+        if let Some(attr) = expr.attrs().iter().find(|a| is_cfg(a)) {
             self.sess.emit_err(RemoveExprNotSupported { span: attr.span });
         }
 

compiler/rustc_expand/src/mbe/metavar_expr.rs

@@ -41,7 +41,7 @@ impl MetaVarExpr {
         };
         check_trailing_token(&mut tts, sess)?;
         let mut iter = args.trees();
-        let rslt = match &*ident.as_str() {
+        let rslt = match ident.as_str() {
             "count" => parse_count(&mut iter, sess, ident.span)?,
             "ignore" => MetaVarExpr::Ignore(parse_ident(&mut iter, sess, ident.span)?),
             "index" => MetaVarExpr::Index(parse_depth(&mut iter, sess, ident.span)?),

compiler/rustc_hir/src/lang_items.rs

@@ -49,7 +49,7 @@ impl LanguageItems {
         self.get(it).ok_or_else(|| LangItemError(it))
     }
 
-    pub fn iter<'a>(&'a self) -> impl Iterator<Item = (LangItem, DefId)> + 'a {
+    pub fn iter(&self) -> impl Iterator<Item = (LangItem, DefId)> + '_ {
         self.items
             .iter()
             .enumerate()

compiler/rustc_hir_analysis/src/coherence/inherent_impls_overlap.rs

@@ -302,7 +302,7 @@ impl<'tcx> InherentOverlapChecker<'tcx> {
                         .iter()
                         .flatten()
                         .map(|r| r.impl_blocks.len() as isize - avg as isize)
-                        .map(|v| v.abs() as usize)
+                        .map(|v| v.unsigned_abs())
                         .sum::<usize>();
                     s / connected_regions.len()
                 },

compiler/rustc_hir_pretty/src/lib.rs

@@ -242,7 +242,7 @@ pub fn enum_def_to_string(
 impl<'a> State<'a> {
     pub fn bclose_maybe_open(&mut self, span: rustc_span::Span, close_box: bool) {
         self.maybe_print_comment(span.hi());
-        self.break_offset_if_not_bol(1, -(INDENT_UNIT as isize));
+        self.break_offset_if_not_bol(1, -INDENT_UNIT);
         self.word("}");
         if close_box {
             self.end(); // close the outer-box

compiler/rustc_hir_typeck/src/_match.rs

@@ -538,8 +538,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 // FIXME(rpitit): This will need to be fixed when we move to associated types
                                 assert!(matches!(
                                     *trait_pred.trait_ref.self_ty().kind(),
-                                    ty::Alias(_, ty::AliasTy { def_id, substs, .. })
-                                    if def_id == rpit_def_id && substs == substs
+                                    ty::Alias(_, ty::AliasTy { def_id, substs: alias_substs, .. })
+                                    if def_id == rpit_def_id && substs == alias_substs
                                 ));
                                 ty::PredicateKind::Clause(ty::Clause::Trait(
                                     trait_pred.with_self_ty(self.tcx, ty),
@@ -548,8 +548,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             ty::PredicateKind::Clause(ty::Clause::Projection(mut proj_pred)) => {
                                 assert!(matches!(
                                     *proj_pred.projection_ty.self_ty().kind(),
-                                    ty::Alias(_, ty::AliasTy { def_id, substs, .. })
-                                    if def_id == rpit_def_id && substs == substs
+                                    ty::Alias(_, ty::AliasTy { def_id, substs: alias_substs, .. })
+                                    if def_id == rpit_def_id && substs == alias_substs
                                 ));
                                 proj_pred = proj_pred.with_self_ty(self.tcx, ty);
                                 ty::PredicateKind::Clause(ty::Clause::Projection(proj_pred))

compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs

@@ -242,8 +242,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let Some(arg) = segment
             .args()
             .args
-            .iter()
-            .nth(index) else { return false; };
+            .get(index) else { return false; };
         error.obligation.cause.span = arg
             .span()
             .find_ancestor_in_same_ctxt(error.obligation.cause.span)

compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_build.rs

@@ -526,8 +526,9 @@ impl DropRangesBuilder {
         let mut next = <_>::from(0u32);
         for value in tracked_values {
             for_each_consumable(hir, value, |value| {
-                if !tracked_value_map.contains_key(&value) {
-                    tracked_value_map.insert(value, next);
+                if let std::collections::hash_map::Entry::Vacant(e) = tracked_value_map.entry(value)
+                {
+                    e.insert(next);
                     next = next + 1;
                 }
             });

compiler/rustc_hir_typeck/src/generator_interior/mod.rs

@@ -313,8 +313,7 @@ pub fn resolve_interior<'a, 'tcx>(
     // Extract type components to build the witness type.
     let type_list = fcx.tcx.mk_type_list_from_iter(type_causes.iter().map(|cause| cause.ty));
     let bound_vars = fcx.tcx.mk_bound_variable_kinds(&bound_vars);
-    let witness =
-        fcx.tcx.mk_generator_witness(ty::Binder::bind_with_vars(type_list, bound_vars.clone()));
+    let witness = fcx.tcx.mk_generator_witness(ty::Binder::bind_with_vars(type_list, bound_vars));
 
     drop(typeck_results);
     // Store the generator types and spans into the typeck results for this generator.

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -1755,16 +1755,15 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
     fn probe_for_similar_candidate(&mut self) -> Result<Option<ty::AssocItem>, MethodError<'tcx>> {
         debug!("probing for method names similar to {:?}", self.method_name);
 
-        let steps = self.steps.clone();
         self.probe(|_| {
             let mut pcx = ProbeContext::new(
                 self.fcx,
                 self.span,
                 self.mode,
                 self.method_name,
                 self.return_type,
-                &self.orig_steps_var_values,
-                steps,
+                self.orig_steps_var_values,
+                self.steps,
                 self.scope_expr_id,
             );
             pcx.allow_similar_names = true;

compiler/rustc_index/src/bit_set.rs

@@ -1850,7 +1850,7 @@ impl<R: Idx, C: Idx> SparseBitMatrix<R, C> {
 
     /// Iterates through all the columns set to true in a given row of
     /// the matrix.
-    pub fn iter<'a>(&'a self, row: R) -> impl Iterator<Item = C> + 'a {
+    pub fn iter(&self, row: R) -> impl Iterator<Item = C> + '_ {
         self.row(row).into_iter().flat_map(|r| r.iter())
     }