Revert "Auto merge of #89709 - clemenswasser:apply_clippy_suggestions_2, r=petrochenkov"

The PR had some unforseen perf regressions that are not as easy to find.
Revert the PR for now.

This reverts commit 6ae8912a3e, reversing
changes made to 86d6d2b738.

compiler/rustc_apfloat/src/ieee.rs

@@ -389,7 +389,6 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let _: Loss = sig::shift_right(&mut sig, &mut exp, trailing_zeros as usize);
 
         // Change the exponent from 2^e to 10^e.
-        #[allow(clippy::comparison_chain)]
         if exp == 0 {
             // Nothing to do.
         } else if exp > 0 {
@@ -2527,7 +2526,6 @@ pub(super) fn add_or_sub(
         if *a_sign ^ b_sign {
             let (reverse, loss);
 
-            #[allow(clippy::comparison_chain)]
             if bits == 0 {
                 reverse = cmp(a_sig, b_sig) == Ordering::Less;
                 loss = Loss::ExactlyZero;

compiler/rustc_data_structures/src/base_n.rs

@@ -14,7 +14,7 @@
 
 #[inline]
 pub fn push_str(mut n: u128, base: usize, output: &mut String) {
-    debug_assert!((2..=MAX_BASE).contains(&base));
+    debug_assert!(base >= 2 && base <= MAX_BASE);
     let mut s = [0u8; 128];
     let mut index = 0;
 

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

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

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

@@ -48,7 +48,7 @@ struct PostOrderFrame<Node, Iter> {
         let node = frame.node;
         visited[node] = true;
 
-        for successor in frame.iter.by_ref() {
+        while let Some(successor) = frame.iter.next() {
             if !visited[successor] {
                 stack.push(PostOrderFrame { node: successor, iter: graph.successors(successor) });
                 continue 'recurse;
@@ -112,7 +112,7 @@ pub fn push_start_node(&mut self, start_node: G::Node) {
     /// This is equivalent to just invoke `next` repeatedly until
     /// you get a `None` result.
     pub fn complete_search(&mut self) {
-        for _ in self {}
+        while let Some(_) = self.next() {}
     }
 
     /// Returns true if node has been visited thus far.

compiler/rustc_data_structures/src/obligation_forest/mod.rs

@@ -390,7 +390,7 @@ pub fn to_errors<E: Clone>(&mut self, error: E) -> Vec<Error<O, E>> {
             .map(|(index, _node)| Error { error: error.clone(), backtrace: self.error_at(index) })
             .collect();
 
-        self.compress(|_| unreachable!());
+        self.compress(|_| assert!(false));
         errors
     }
 
@@ -612,7 +612,7 @@ fn find_cycles_from_node<P>(&self, stack: &mut Vec<usize>, processor: &mut P, in
     fn compress(&mut self, mut outcome_cb: impl FnMut(&O)) {
         let orig_nodes_len = self.nodes.len();
         let mut node_rewrites: Vec<_> = std::mem::take(&mut self.reused_node_vec);
-        assert!(node_rewrites.is_empty());
+        debug_assert!(node_rewrites.is_empty());
         node_rewrites.extend(0..orig_nodes_len);
         let mut dead_nodes = 0;
 
@@ -623,13 +623,13 @@ fn compress(&mut self, mut outcome_cb: impl FnMut(&O)) {
         //     self.nodes[0..index - dead_nodes] are the first remaining nodes
         //     self.nodes[index - dead_nodes..index] are all dead
         //     self.nodes[index..] are unchanged
-        for (index, node_rewrite) in node_rewrites.iter_mut().enumerate() {
+        for index in 0..orig_nodes_len {
             let node = &self.nodes[index];
             match node.state.get() {
                 NodeState::Pending | NodeState::Waiting => {
                     if dead_nodes > 0 {
                         self.nodes.swap(index, index - dead_nodes);
-                        *node_rewrite -= dead_nodes;
+                        node_rewrites[index] -= dead_nodes;
                     }
                 }
                 NodeState::Done => {
@@ -646,7 +646,7 @@ fn compress(&mut self, mut outcome_cb: impl FnMut(&O)) {
                     }
                     // Extract the success stories.
                     outcome_cb(&node.obligation);
-                    *node_rewrite = orig_nodes_len;
+                    node_rewrites[index] = orig_nodes_len;
                     dead_nodes += 1;
                 }
                 NodeState::Error => {
@@ -655,7 +655,7 @@ fn compress(&mut self, mut outcome_cb: impl FnMut(&O)) {
                     // check against.
                     self.active_cache.remove(&node.obligation.as_cache_key());
                     self.insert_into_error_cache(index);
-                    *node_rewrite = orig_nodes_len;
+                    node_rewrites[index] = orig_nodes_len;
                     dead_nodes += 1;
                 }
                 NodeState::Success => unreachable!(),

compiler/rustc_data_structures/src/sorted_map.rs

@@ -205,10 +205,10 @@ fn range_slice_indices<R>(&self, range: R) -> (usize, usize)
         R: RangeBounds<K>,
     {
         let start = match range.start_bound() {
-            Bound::Included(k) => match self.lookup_index_for(k) {
+            Bound::Included(ref k) => match self.lookup_index_for(k) {
                 Ok(index) | Err(index) => index,
             },
-            Bound::Excluded(k) => match self.lookup_index_for(k) {
+            Bound::Excluded(ref k) => match self.lookup_index_for(k) {
                 Ok(index) => index + 1,
                 Err(index) => index,
             },
@@ -216,11 +216,11 @@ fn range_slice_indices<R>(&self, range: R) -> (usize, usize)
         };
 
         let end = match range.end_bound() {
-            Bound::Included(k) => match self.lookup_index_for(k) {
+            Bound::Included(ref k) => match self.lookup_index_for(k) {
                 Ok(index) => index + 1,
                 Err(index) => index,
             },
-            Bound::Excluded(k) => match self.lookup_index_for(k) {
+            Bound::Excluded(ref k) => match self.lookup_index_for(k) {
                 Ok(index) | Err(index) => index,
             },
             Bound::Unbounded => self.data.len(),

compiler/rustc_data_structures/src/sorted_map/index_map.rs

@@ -75,7 +75,7 @@ pub fn get(&self, idx: I) -> Option<&(K, V)> {
     ///
     /// If there are multiple items that are equivalent to `key`, they will be yielded in
     /// insertion order.
-    pub fn get_by_key(&self, key: K) -> impl Iterator<Item = &V> {
+    pub fn get_by_key(&'a self, key: K) -> impl 'a + Iterator<Item = &'a V> {
         self.get_by_key_enumerated(key).map(|(_, v)| v)
     }
 
@@ -84,7 +84,7 @@ pub fn get_by_key(&self, key: K) -> impl Iterator<Item = &V> {
     ///
     /// If there are multiple items that are equivalent to `key`, they will be yielded in
     /// insertion order.
-    pub fn get_by_key_enumerated(&self, key: K) -> impl Iterator<Item = (I, &V)> {
+    pub fn get_by_key_enumerated(&'a self, key: K) -> impl '_ + Iterator<Item = (I, &V)> {
         let lower_bound = self.idx_sorted_by_item_key.partition_point(|&i| self.items[i].0 < key);
         self.idx_sorted_by_item_key[lower_bound..].iter().map_while(move |&i| {
             let (k, v) = &self.items[i];

compiler/rustc_data_structures/src/sso/map.rs

@@ -257,7 +257,11 @@ pub fn insert(&mut self, key: K, value: V) -> Option<V> {
     pub fn remove(&mut self, key: &K) -> Option<V> {
         match self {
             SsoHashMap::Array(array) => {
-                array.iter().position(|(k, _v)| k == key).map(|index| array.swap_remove(index).1)
+                if let Some(index) = array.iter().position(|(k, _v)| k == key) {
+                    Some(array.swap_remove(index).1)
+                } else {
+                    None
+                }
             }
             SsoHashMap::Map(map) => map.remove(key),
         }
@@ -268,7 +272,11 @@ pub fn remove(&mut self, key: &K) -> Option<V> {
     pub fn remove_entry(&mut self, key: &K) -> Option<(K, V)> {
         match self {
             SsoHashMap::Array(array) => {
-                array.iter().position(|(k, _v)| k == key).map(|index| array.swap_remove(index))
+                if let Some(index) = array.iter().position(|(k, _v)| k == key) {
+                    Some(array.swap_remove(index))
+                } else {
+                    None
+                }
             }
             SsoHashMap::Map(map) => map.remove_entry(key),
         }
@@ -415,14 +423,14 @@ fn into_iter(self) -> Self::IntoIter {
 
 /// adapts Item of array reference iterator to Item of hashmap reference iterator.
 #[inline(always)]
-fn adapt_array_ref_it<K, V>(pair: &(K, V)) -> (&K, &V) {
+fn adapt_array_ref_it<K, V>(pair: &'a (K, V)) -> (&'a K, &'a V) {
     let (a, b) = pair;
     (a, b)
 }
 
 /// adapts Item of array mut reference iterator to Item of hashmap mut reference iterator.
 #[inline(always)]
-fn adapt_array_mut_it<K, V>(pair: &mut (K, V)) -> (&K, &mut V) {
+fn adapt_array_mut_it<K, V>(pair: &'a mut (K, V)) -> (&'a K, &'a mut V) {
     let (a, b) = pair;
     (a, b)
 }

compiler/rustc_data_structures/src/sso/set.rs

@@ -75,7 +75,7 @@ pub fn is_empty(&self) -> bool {
     /// An iterator visiting all elements in arbitrary order.
     /// The iterator element type is `&'a T`.
     #[inline]
-    pub fn iter(&self) -> impl Iterator<Item = &T> {
+    pub fn iter(&'a self) -> impl Iterator<Item = &'a T> {
         self.into_iter()
     }
 

compiler/rustc_data_structures/src/stable_hasher.rs

@@ -229,14 +229,14 @@ fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
 
 impl<CTX> HashStable<CTX> for f32 {
     fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
-        let val: u32 = self.to_bits();
+        let val: u32 = unsafe { ::std::mem::transmute(*self) };
         val.hash_stable(ctx, hasher);
     }
 }
 
 impl<CTX> HashStable<CTX> for f64 {
     fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
-        let val: u64 = self.to_bits();
+        let val: u64 = unsafe { ::std::mem::transmute(*self) };
         val.hash_stable(ctx, hasher);
     }
 }

compiler/rustc_data_structures/src/stack.rs

@@ -5,7 +5,6 @@
 
 // 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.
-#[allow(clippy::identity_op)]
 const STACK_PER_RECURSION: usize = 1 * 1024 * 1024; // 1MB
 
 /// Grows the stack on demand to prevent stack overflow. Call this in strategic locations

compiler/rustc_data_structures/src/steal.rs

@@ -34,7 +34,7 @@ pub fn new(value: T) -> Self {
     #[track_caller]
     pub fn borrow(&self) -> MappedReadGuard<'_, T> {
         let borrow = self.value.borrow();
-        if borrow.is_none() {
+        if let None = &*borrow {
             panic!("attempted to read from stolen value: {}", std::any::type_name::<T>());
         }
         ReadGuard::map(borrow, |opt| opt.as_ref().unwrap())

compiler/rustc_data_structures/src/tiny_list.rs

@@ -48,7 +48,7 @@ pub fn remove(&mut self, data: &T) -> bool {
     #[inline]
     pub fn contains(&self, data: &T) -> bool {
         let mut elem = self.head.as_ref();
-        while let Some(e) = elem {
+        while let Some(ref e) = elem {
             if &e.data == data {
                 return true;
             }

compiler/rustc_data_structures/src/vec_linked_list.rs

@@ -2,8 +2,8 @@
 
 pub fn iter<Ls>(
     first: Option<Ls::LinkIndex>,
-    links: &Ls,
-) -> impl Iterator<Item = Ls::LinkIndex> + '_
+    links: &'a Ls,
+) -> impl Iterator<Item = Ls::LinkIndex> + 'a
 where
     Ls: Links,
 {

compiler/rustc_graphviz/src/lib.rs

@@ -512,7 +512,7 @@ fn escape_str(s: &str) -> String {
     pub fn to_dot_string(&self) -> String {
         match *self {
             LabelStr(ref s) => format!("\"{}\"", s.escape_default()),
-            EscStr(ref s) => format!("\"{}\"", LabelText::escape_str(s)),
+            EscStr(ref s) => format!("\"{}\"", LabelText::escape_str(&s)),
             HtmlStr(ref s) => format!("<{}>", s),
         }
     }

compiler/rustc_index/src/bit_set.rs

@@ -990,8 +990,9 @@ pub fn union_row_with(&mut self, with: &BitSet<C>, write: R) -> bool {
     pub fn insert_all_into_row(&mut self, row: R) {
         assert!(row.index() < self.num_rows);
         let (start, end) = self.range(row);
-        for word in self.words[start..end].iter_mut() {
-            *word = !0;
+        let words = &mut self.words[..];
+        for index in start..end {
+            words[index] = !0;
         }
         self.clear_excess_bits(row);
     }
@@ -1143,7 +1144,7 @@ pub fn rows(&self) -> impl Iterator<Item = R> {
 
     /// Iterates through all the columns set to true in a given row of
     /// the matrix.
-    pub fn iter(&self, row: R) -> impl Iterator<Item = C> + '_ {
+    pub fn iter<'a>(&'a self, row: R) -> impl Iterator<Item = C> + 'a {
         self.row(row).into_iter().flat_map(|r| r.iter())
     }
 

compiler/rustc_index/src/vec.rs

@@ -634,15 +634,18 @@ pub fn iter_enumerated_mut(
     }
 
     #[inline]
-    pub fn drain<R: RangeBounds<usize>>(&mut self, range: R) -> impl Iterator<Item = T> + '_ {
+    pub fn drain<'a, R: RangeBounds<usize>>(
+        &'a mut self,
+        range: R,
+    ) -> impl Iterator<Item = T> + 'a {
         self.raw.drain(range)
     }
 
     #[inline]
-    pub fn drain_enumerated<R: RangeBounds<usize>>(
-        &mut self,
+    pub fn drain_enumerated<'a, R: RangeBounds<usize>>(
+        &'a mut self,
         range: R,
-    ) -> impl Iterator<Item = (I, T)> + '_ {
+    ) -> impl Iterator<Item = (I, T)> + 'a {
         self.raw.drain(range).enumerate().map(|(n, t)| (I::new(n), t))
     }
 

compiler/rustc_lexer/src/unescape.rs

@@ -68,10 +68,11 @@ pub enum EscapeError {
 impl EscapeError {
     /// Returns true for actual errors, as opposed to warnings.
     pub fn is_fatal(&self) -> bool {
-        !matches!(
-            self,
-            EscapeError::UnskippedWhitespaceWarning | EscapeError::MultipleSkippedLinesWarning
-        )
+        match self {
+            EscapeError::UnskippedWhitespaceWarning => false,
+            EscapeError::MultipleSkippedLinesWarning => false,
+            _ => true,
+        }
     }
 }
 
@@ -329,7 +330,7 @@ fn skip_ascii_whitespace<F>(chars: &mut Chars<'_>, start: usize, callback: &mut
             callback(start..end, Err(EscapeError::MultipleSkippedLinesWarning));
         }
         let tail = &tail[first_non_space..];
-        if let Some(c) = tail.chars().next() {
+        if let Some(c) = tail.chars().nth(0) {
             // For error reporting, we would like the span to contain the character that was not
             // skipped.  The +1 is necessary to account for the leading \ that started the escape.
             let end = start + first_non_space + c.len_utf8() + 1;

compiler/rustc_macros/src/hash_stable.rs

@@ -24,7 +24,8 @@ fn parse_attributes(field: &syn::Field) -> Attributes {
                         }
                         if meta.path().is_ident("project") {
                             if let Meta::List(list) = meta {
-                                if let Some(NestedMeta::Meta(meta)) = list.nested.iter().next() {
+                                if let Some(nested) = list.nested.iter().next() {
+                                    if let NestedMeta::Meta(meta) = nested {
                                         attrs.project = meta.path().get_ident().cloned();
                                         any_attr = true;
                                     }
@@ -33,6 +34,7 @@ fn parse_attributes(field: &syn::Field) -> Attributes {
                         }
                     }
                 }
+            }
             if !any_attr {
                 panic!("error parsing stable_hasher");
             }

compiler/rustc_macros/src/session_diagnostic.rs

@@ -349,14 +349,14 @@ fn generate_field_code(
     ) -> Result<proc_macro2::TokenStream, SessionDiagnosticDeriveError> {
         let field_binding = &info.binding.binding;
 
-        let option_ty = option_inner_ty(info.ty);
+        let option_ty = option_inner_ty(&info.ty);
 
         let generated_code = self.generate_non_option_field_code(
             attr,
             FieldInfo {
                 vis: info.vis,
                 binding: info.binding,
-                ty: option_ty.unwrap_or(info.ty),
+                ty: option_ty.unwrap_or(&info.ty),
                 span: info.span,
             },
         )?;
@@ -388,7 +388,7 @@ fn generate_non_option_field_code(
                 let formatted_str = self.build_format(&s.value(), attr.span());
                 match name {
                     "message" => {
-                        if type_matches_path(info.ty, &["rustc_span", "Span"]) {
+                        if type_matches_path(&info.ty, &["rustc_span", "Span"]) {
                             quote! {
                                 #diag.set_span(*#field_binding);
                                 #diag.set_primary_message(#formatted_str);
@@ -401,7 +401,7 @@ fn generate_non_option_field_code(
                         }
                     }
                     "label" => {
-                        if type_matches_path(info.ty, &["rustc_span", "Span"]) {
+                        if type_matches_path(&info.ty, &["rustc_span", "Span"]) {
                             quote! {
                                 #diag.span_label(*#field_binding, #formatted_str);
                             }

compiler/rustc_serialize/src/serialize.rs

@@ -500,8 +500,8 @@ fn encode(&self, s: &mut S) -> Result<(), S::Error> {
         d.read_seq(|d, len| {
             assert!(len == N);
             let mut v = [0u8; N];
-            for x in &mut v {
-                *x = d.read_seq_elt(|d| Decodable::decode(d))?;
+            for i in 0..len {
+                v[i] = d.read_seq_elt(|d| Decodable::decode(d))?;
             }
             Ok(v)
         })

library/core/src/num/fmt.rs

@@ -31,10 +31,8 @@ pub fn len(&self) -> usize {
                     } else {
                         3
                     }
-                } else if v < 10_000 {
-                    4
                 } else {
-                    5
+                    if v < 10_000 { 4 } else { 5 }
                 }
             }
             Part::Copy(buf) => buf.len(),