Fix some clippy::complexity

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_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

@@ -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/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_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())
     }
 

compiler/rustc_index/src/vec.rs

@@ -201,18 +201,15 @@ impl<I: Idx, T> IndexVec<I, T> {
     }
 
     #[inline]
-    pub fn drain<'a, R: RangeBounds<usize>>(
-        &'a mut self,
-        range: R,
-    ) -> impl Iterator<Item = T> + 'a {
+    pub fn drain<R: RangeBounds<usize>>(&mut self, range: R) -> impl Iterator<Item = T> + '_ {
         self.raw.drain(range)
     }
 
     #[inline]
-    pub fn drain_enumerated<'a, R: RangeBounds<usize>>(
-        &'a mut self,
+    pub fn drain_enumerated<R: RangeBounds<usize>>(
+        &mut self,
         range: R,
-    ) -> impl Iterator<Item = (I, T)> + 'a {
+    ) -> impl Iterator<Item = (I, T)> + '_ {
         let begin = match range.start_bound() {
             std::ops::Bound::Included(i) => *i,
             std::ops::Bound::Excluded(i) => i.checked_add(1).unwrap(),

compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs

@@ -119,7 +119,7 @@ impl DiagnosticDeriveBuilder {
 impl<'a> DiagnosticDeriveVariantBuilder<'a> {
     /// Generates calls to `code` and similar functions based on the attributes on the type or
     /// variant.
-    pub fn preamble<'s>(&mut self, variant: &VariantInfo<'s>) -> TokenStream {
+    pub fn preamble(&mut self, variant: &VariantInfo<'_>) -> TokenStream {
         let ast = variant.ast();
         let attrs = &ast.attrs;
         let preamble = attrs.iter().map(|attr| {
@@ -133,7 +133,7 @@ impl<'a> DiagnosticDeriveVariantBuilder<'a> {
 
     /// Generates calls to `span_label` and similar functions based on the attributes on fields or
     /// calls to `set_arg` when no attributes are present.
-    pub fn body<'s>(&mut self, variant: &VariantInfo<'s>) -> TokenStream {
+    pub fn body(&mut self, variant: &VariantInfo<'_>) -> TokenStream {
         let mut body = quote! {};
         // Generate `set_arg` calls first..
         for binding in variant.bindings().iter().filter(|bi| should_generate_set_arg(bi.ast())) {

compiler/rustc_middle/src/mir/mod.rs

@@ -915,7 +915,7 @@ pub enum LocalInfo<'tcx> {
 
 impl<'tcx> LocalDecl<'tcx> {
     pub fn local_info(&self) -> &LocalInfo<'tcx> {
-        &**self.local_info.as_ref().assert_crate_local()
+        &self.local_info.as_ref().assert_crate_local()
     }
 
     /// Returns `true` only if local is a binding that can itself be

compiler/rustc_middle/src/traits/mod.rs

@@ -923,7 +923,7 @@ impl ObjectSafetyViolation {
                 }
             }
             ObjectSafetyViolation::SupertraitNonLifetimeBinder(_) => {
-                format!("where clause cannot reference non-lifetime `for<...>` variables").into()
+                "where clause cannot reference non-lifetime `for<...>` variables".into()
             }
             ObjectSafetyViolation::Method(name, MethodViolationCode::StaticMethod(_), _) => {
                 format!("associated function `{}` has no `self` parameter", name).into()

compiler/rustc_middle/src/traits/solve.rs

@@ -105,7 +105,7 @@ impl<'tcx> std::ops::Deref for ExternalConstraints<'tcx> {
     type Target = ExternalConstraintsData<'tcx>;
 
     fn deref(&self) -> &Self::Target {
-        &*self.0
+        &self.0
     }
 }
 

compiler/rustc_middle/src/ty/context.rs

@@ -924,7 +924,7 @@ impl<'tcx> TyCtxt<'tcx> {
             crate_name,
             // Don't print the whole stable crate id. That's just
             // annoying in debug output.
-            stable_crate_id.to_u64() >> 8 * 6,
+            stable_crate_id.to_u64() >> (8 * 6),
             self.def_path(def_id).to_string_no_crate_verbose()
         )
     }
@@ -2379,7 +2379,7 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn in_scope_traits(self, id: HirId) -> Option<&'tcx [TraitCandidate]> {
         let map = self.in_scope_traits_map(id.owner)?;
         let candidates = map.get(&id.local_id)?;
-        Some(&*candidates)
+        Some(candidates)
     }
 
     pub fn named_bound_var(self, id: HirId) -> Option<resolve_bound_vars::ResolvedArg> {

compiler/rustc_parse/src/lexer/unicode_chars.rs

@@ -336,8 +336,8 @@ const ASCII_ARRAY: &[(&str, &str, Option<token::TokenKind>)] = &[
     ("\"", "Quotation Mark", None),
 ];
 
-pub(super) fn check_for_substitution<'a>(
-    reader: &StringReader<'a>,
+pub(super) fn check_for_substitution(
+    reader: &StringReader<'_>,
     pos: BytePos,
     ch: char,
     count: usize,

compiler/rustc_parse/src/parser/generics.rs

@@ -53,7 +53,7 @@ impl<'a> Parser<'a> {
                 let snapshot = self.create_snapshot_for_diagnostic();
                 match self.parse_ty() {
                     Ok(p) => {
-                        if let TyKind::ImplTrait(_, bounds) = &(*p).kind {
+                        if let TyKind::ImplTrait(_, bounds) = &p.kind {
                             let span = impl_span.to(self.token.span.shrink_to_lo());
                             let mut err = self.struct_span_err(
                                 span,

compiler/rustc_query_system/src/query/caches.rs

@@ -136,7 +136,9 @@ where
     }
 
     fn iter(&self, f: &mut dyn FnMut(&Self::Key, &Self::Value, DepNodeIndex)) {
-        self.cache.lock().as_ref().map(|value| f(&(), &value.0, value.1));
+        if let Some(value) = self.cache.lock().as_ref() {
+            f(&(), &value.0, value.1)
+        }
     }
 }
 

compiler/rustc_session/src/config.rs

@@ -1426,7 +1426,7 @@ pub fn rustc_short_optgroups() -> Vec<RustcOptGroup> {
         opt::opt_s(
             "",
             "edition",
-            &*EDITION_STRING,
+            &EDITION_STRING,
             EDITION_NAME_LIST,
         ),
         opt::multi_s(

compiler/rustc_session/src/parse.rs

@@ -84,12 +84,12 @@ impl SymbolGallery {
 
 /// Construct a diagnostic for a language feature error due to the given `span`.
 /// The `feature`'s `Symbol` is the one you used in `active.rs` and `rustc_span::symbols`.
-pub fn feature_err<'a>(
-    sess: &'a ParseSess,
+pub fn feature_err(
+    sess: &ParseSess,
     feature: Symbol,
     span: impl Into<MultiSpan>,
     explain: impl Into<DiagnosticMessage>,
-) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
+) -> DiagnosticBuilder<'_, ErrorGuaranteed> {
     feature_err_issue(sess, feature, span, GateIssue::Language, explain)
 }
 
@@ -98,20 +98,21 @@ pub fn feature_err<'a>(
 /// This variant allows you to control whether it is a library or language feature.
 /// Almost always, you want to use this for a language feature. If so, prefer `feature_err`.
 #[track_caller]
-pub fn feature_err_issue<'a>(
-    sess: &'a ParseSess,
+pub fn feature_err_issue(
+    sess: &ParseSess,
     feature: Symbol,
     span: impl Into<MultiSpan>,
     issue: GateIssue,
     explain: impl Into<DiagnosticMessage>,
-) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
+) -> DiagnosticBuilder<'_, ErrorGuaranteed> {
     let span = span.into();
 
     // Cancel an earlier warning for this same error, if it exists.
     if let Some(span) = span.primary_span() {
-        sess.span_diagnostic
-            .steal_diagnostic(span, StashKey::EarlySyntaxWarning)
-            .map(|err| err.cancel());
+        if let Some(err) = sess.span_diagnostic.steal_diagnostic(span, StashKey::EarlySyntaxWarning)
+        {
+            err.cancel()
+        }
     }
 
     let mut err = sess.create_err(FeatureGateError { span, explain: explain.into() });

compiler/rustc_span/src/lib.rs

@@ -1353,16 +1353,16 @@ impl Clone for SourceFile {
         Self {
             name: self.name.clone(),
             src: self.src.clone(),
-            src_hash: self.src_hash.clone(),
+            src_hash: self.src_hash,
             external_src: Lock::new(self.external_src.borrow().clone()),
-            start_pos: self.start_pos.clone(),
-            end_pos: self.end_pos.clone(),
+            start_pos: self.start_pos,
+            end_pos: self.end_pos,
             lines: Lock::new(self.lines.borrow().clone()),
             multibyte_chars: self.multibyte_chars.clone(),
             non_narrow_chars: self.non_narrow_chars.clone(),
             normalized_pos: self.normalized_pos.clone(),
-            name_hash: self.name_hash.clone(),
-            cnum: self.cnum.clone(),
+            name_hash: self.name_hash,
+            cnum: self.cnum,
         }
     }
 }