diff --git a/Cargo.lock b/Cargo.lock
index 34fc0860a4b75..ad8fada320d61 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3354,7 +3354,6 @@ version = "0.0.0"
 dependencies = [
  "rustc_abi",
  "rustc_ast",
- "rustc_ast_pretty",
  "rustc_attr_data_structures",
  "rustc_attr_parsing",
  "rustc_data_structures",
diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index 491a9bbda79b1..8ae5f5fad2061 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -4054,6 +4054,17 @@ impl TryFrom<ItemKind> for ForeignItemKind {
 
 pub type ForeignItem = Item<ForeignItemKind>;
 
+#[derive(Debug)]
+pub enum AstOwner {
+    NonOwner,
+    Synthetic(rustc_span::def_id::LocalDefId),
+    Crate(P<Crate>),
+    Item(P<Item>),
+    TraitItem(P<AssocItem>),
+    ImplItem(P<AssocItem>),
+    ForeignItem(P<ForeignItem>),
+}
+
 // Some nodes are used a lot. Make sure they don't unintentionally get bigger.
 #[cfg(target_pointer_width = "64")]
 mod size_asserts {
diff --git a/compiler/rustc_ast/src/mut_visit.rs b/compiler/rustc_ast/src/mut_visit.rs
index 3eae19f4daa11..f9c018da90992 100644
--- a/compiler/rustc_ast/src/mut_visit.rs
+++ b/compiler/rustc_ast/src/mut_visit.rs
@@ -142,7 +142,10 @@ pub fn walk_flat_map_stmt<T: MutVisitor>(
     stmts
 }
 
-fn walk_flat_map_stmt_kind<T: MutVisitor>(vis: &mut T, kind: StmtKind) -> SmallVec<[StmtKind; 1]> {
+pub fn walk_flat_map_stmt_kind<T: MutVisitor>(
+    vis: &mut T,
+    kind: StmtKind,
+) -> SmallVec<[StmtKind; 1]> {
     match kind {
         StmtKind::Let(mut local) => smallvec![StmtKind::Let({
             vis.visit_local(&mut local);
diff --git a/compiler/rustc_ast_lowering/Cargo.toml b/compiler/rustc_ast_lowering/Cargo.toml
index dc571f5c3671a..6e23549047f1f 100644
--- a/compiler/rustc_ast_lowering/Cargo.toml
+++ b/compiler/rustc_ast_lowering/Cargo.toml
@@ -10,7 +10,6 @@ doctest = false
 # tidy-alphabetical-start
 rustc_abi = { path = "../rustc_abi" }
 rustc_ast = { path = "../rustc_ast" }
-rustc_ast_pretty = { path = "../rustc_ast_pretty" }
 rustc_attr_data_structures = { path = "../rustc_attr_data_structures" }
 rustc_attr_parsing = { path = "../rustc_attr_parsing" }
 rustc_data_structures = { path = "../rustc_data_structures" }
diff --git a/compiler/rustc_ast_lowering/src/asm.rs b/compiler/rustc_ast_lowering/src/asm.rs
index af279e07acc6e..c65860ddd1360 100644
--- a/compiler/rustc_ast_lowering/src/asm.rs
+++ b/compiler/rustc_ast_lowering/src/asm.rs
@@ -20,10 +20,10 @@ use super::errors::{
 };
 use crate::{
     AllowReturnTypeNotation, ImplTraitContext, ImplTraitPosition, ParamMode,
-    ResolverAstLoweringExt, fluent_generated as fluent,
+    fluent_generated as fluent,
 };
 
-impl<'a, 'hir> LoweringContext<'a, 'hir> {
+impl<'hir> LoweringContext<'hir> {
     pub(crate) fn lower_inline_asm(
         &mut self,
         sp: Span,
@@ -200,7 +200,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     },
                     InlineAsmOperand::Sym { sym } => {
                         let static_def_id = self
-                            .resolver
                             .get_partial_res(sym.id)
                             .and_then(|res| res.full_res())
                             .and_then(|res| match res {
diff --git a/compiler/rustc_ast_lowering/src/block.rs b/compiler/rustc_ast_lowering/src/block.rs
index c3222b79e55c9..3bc05b22a408b 100644
--- a/compiler/rustc_ast_lowering/src/block.rs
+++ b/compiler/rustc_ast_lowering/src/block.rs
@@ -5,7 +5,7 @@ use smallvec::SmallVec;
 
 use crate::{ImplTraitContext, ImplTraitPosition, LoweringContext};
 
-impl<'a, 'hir> LoweringContext<'a, 'hir> {
+impl<'hir> LoweringContext<'hir> {
     pub(super) fn lower_block(
         &mut self,
         b: &Block,
@@ -43,17 +43,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     stmts.push(hir::Stmt { hir_id, kind, span });
                 }
                 StmtKind::Item(it) => {
-                    stmts.extend(self.lower_item_ref(it).into_iter().enumerate().map(
-                        |(i, item_id)| {
-                            let hir_id = match i {
-                                0 => self.lower_node_id(s.id),
-                                _ => self.next_id(),
-                            };
-                            let kind = hir::StmtKind::Item(item_id);
-                            let span = self.lower_span(s.span);
-                            hir::Stmt { hir_id, kind, span }
-                        },
-                    ));
+                    let item_id = self.lower_item_ref(it);
+                    let hir_id = self.lower_node_id(s.id);
+                    let kind = hir::StmtKind::Item(item_id);
+                    let span = self.lower_span(s.span);
+                    stmts.push(hir::Stmt { hir_id, kind, span });
                 }
                 StmtKind::Expr(e) => {
                     let e = self.lower_expr(e);
diff --git a/compiler/rustc_ast_lowering/src/delegation.rs b/compiler/rustc_ast_lowering/src/delegation.rs
index 42d25b512f5c9..575c2ff4b38a6 100644
--- a/compiler/rustc_ast_lowering/src/delegation.rs
+++ b/compiler/rustc_ast_lowering/src/delegation.rs
@@ -46,12 +46,15 @@ use rustc_ast::*;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def_id::DefId;
 use rustc_middle::span_bug;
-use rustc_middle::ty::{Asyncness, ResolverAstLowering};
+use rustc_middle::ty::Asyncness;
+use rustc_span::symbol::kw;
 use rustc_span::{Ident, Span, Symbol};
 use {rustc_ast as ast, rustc_hir as hir};
 
-use super::{GenericArgsMode, ImplTraitContext, LoweringContext, ParamMode};
-use crate::{AllowReturnTypeNotation, ImplTraitPosition, ResolverAstLoweringExt};
+use super::{
+    AllowReturnTypeNotation, GenericArgsMode, ImplTraitContext, ImplTraitPosition, LoweringContext,
+    ParamMode,
+};
 
 pub(crate) struct DelegationResults<'hir> {
     pub body_id: hir::BodyId,
@@ -60,22 +63,7 @@ pub(crate) struct DelegationResults<'hir> {
     pub generics: &'hir hir::Generics<'hir>,
 }
 
-impl<'hir> LoweringContext<'_, 'hir> {
-    /// Defines whether the delegatee is an associated function whose first parameter is `self`.
-    pub(crate) fn delegatee_is_method(
-        &self,
-        item_id: NodeId,
-        path_id: NodeId,
-        span: Span,
-        is_in_trait_impl: bool,
-    ) -> bool {
-        let sig_id = self.get_delegation_sig_id(item_id, path_id, span, is_in_trait_impl);
-        let Ok(sig_id) = sig_id else {
-            return false;
-        };
-        self.is_method(sig_id, span)
-    }
-
+impl<'hir> LoweringContext<'hir> {
     fn is_method(&self, def_id: DefId, span: Span) -> bool {
         match self.tcx.def_kind(def_id) {
             DefKind::Fn => false,
@@ -101,10 +89,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
         let sig_id = self.get_delegation_sig_id(item_id, delegation.id, span, is_in_trait_impl);
         match sig_id {
             Ok(sig_id) => {
+                let is_method = self.is_method(sig_id, span);
                 let (param_count, c_variadic) = self.param_count(sig_id);
                 let decl = self.lower_delegation_decl(sig_id, param_count, c_variadic, span);
                 let sig = self.lower_delegation_sig(sig_id, decl, span);
-                let body_id = self.lower_delegation_body(delegation, param_count, span);
+                let body_id = self.lower_delegation_body(delegation, is_method, param_count, span);
                 let ident = self.lower_ident(delegation.ident);
                 let generics = self.lower_delegation_generics(span);
                 DelegationResults { body_id, sig, ident, generics }
@@ -125,8 +114,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
     }
 
     fn get_resolution_id(&self, node_id: NodeId, span: Span) -> Result<DefId, ErrorGuaranteed> {
-        let def_id =
-            self.resolver.get_partial_res(node_id).and_then(|r| r.expect_full_res().opt_def_id());
+        let def_id = self.get_partial_res(node_id).and_then(|r| r.expect_full_res().opt_def_id());
         def_id.ok_or_else(|| {
             self.tcx.dcx().span_delayed_bug(
                 span,
@@ -234,10 +222,21 @@ impl<'hir> LoweringContext<'_, 'hir> {
         hir::FnSig { decl, header, span }
     }
 
-    fn generate_param(&mut self, idx: usize, span: Span) -> (hir::Param<'hir>, NodeId) {
+    fn generate_param(
+        &mut self,
+        is_method: bool,
+        idx: usize,
+        span: Span,
+    ) -> (hir::Param<'hir>, NodeId) {
         let pat_node_id = self.next_node_id();
         let pat_id = self.lower_node_id(pat_node_id);
-        let ident = Ident::with_dummy_span(Symbol::intern(&format!("arg{idx}")));
+        // FIXME(cjgillot) AssocItem currently relies on self parameter being exactly named `self`.
+        let name = if is_method && idx == 0 {
+            kw::SelfLower
+        } else {
+            Symbol::intern(&format!("arg{idx}"))
+        };
+        let ident = Ident::with_dummy_span(name);
         let pat = self.arena.alloc(hir::Pat {
             hir_id: pat_id,
             kind: hir::PatKind::Binding(hir::BindingMode::NONE, pat_id, ident, None),
@@ -248,9 +247,21 @@ impl<'hir> LoweringContext<'_, 'hir> {
         (hir::Param { hir_id: self.next_id(), pat, ty_span: span, span }, pat_node_id)
     }
 
-    fn generate_arg(&mut self, idx: usize, param_id: HirId, span: Span) -> hir::Expr<'hir> {
+    fn generate_arg(
+        &mut self,
+        is_method: bool,
+        idx: usize,
+        param_id: HirId,
+        span: Span,
+    ) -> hir::Expr<'hir> {
+        // FIXME(cjgillot) AssocItem currently relies on self parameter being exactly named `self`.
+        let name = if is_method && idx == 0 {
+            kw::SelfLower
+        } else {
+            Symbol::intern(&format!("arg{idx}"))
+        };
         let segments = self.arena.alloc_from_iter(iter::once(hir::PathSegment {
-            ident: Ident::with_dummy_span(Symbol::intern(&format!("arg{idx}"))),
+            ident: Ident::with_dummy_span(name),
             hir_id: self.next_id(),
             res: Res::Local(param_id),
             args: None,
@@ -264,6 +275,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
     fn lower_delegation_body(
         &mut self,
         delegation: &Delegation,
+        is_method: bool,
         param_count: usize,
         span: Span,
     ) -> BodyId {
@@ -274,14 +286,14 @@ impl<'hir> LoweringContext<'_, 'hir> {
             let mut args: Vec<hir::Expr<'_>> = Vec::with_capacity(param_count);
 
             for idx in 0..param_count {
-                let (param, pat_node_id) = this.generate_param(idx, span);
+                let (param, pat_node_id) = this.generate_param(is_method, idx, span);
                 parameters.push(param);
 
                 let arg = if let Some(block) = block
                     && idx == 0
                 {
                     let mut self_resolver = SelfResolver {
-                        resolver: this.resolver,
+                        ctxt: this,
                         path_id: delegation.id,
                         self_param_id: pat_node_id,
                     };
@@ -290,7 +302,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     this.ident_and_label_to_local_id.insert(pat_node_id, param.pat.hir_id.local_id);
                     this.lower_target_expr(&block)
                 } else {
-                    this.generate_arg(idx, param.pat.hir_id, span)
+                    this.generate_arg(is_method, idx, param.pat.hir_id, span)
                 };
                 args.push(arg);
             }
@@ -427,25 +439,25 @@ impl<'hir> LoweringContext<'_, 'hir> {
     }
 }
 
-struct SelfResolver<'a> {
-    resolver: &'a mut ResolverAstLowering,
+struct SelfResolver<'r, 'hir> {
+    ctxt: &'r mut LoweringContext<'hir>,
     path_id: NodeId,
     self_param_id: NodeId,
 }
 
-impl<'a> SelfResolver<'a> {
+impl SelfResolver<'_, '_> {
     fn try_replace_id(&mut self, id: NodeId) {
-        if let Some(res) = self.resolver.partial_res_map.get(&id)
+        if let Some(res) = self.ctxt.get_partial_res(id)
             && let Some(Res::Local(sig_id)) = res.full_res()
             && sig_id == self.path_id
         {
             let new_res = PartialRes::new(Res::Local(self.self_param_id));
-            self.resolver.partial_res_map.insert(id, new_res);
+            self.ctxt.partial_res_overrides.insert(id, new_res);
         }
     }
 }
 
-impl<'ast, 'a> Visitor<'ast> for SelfResolver<'a> {
+impl<'ast> Visitor<'ast> for SelfResolver<'_, '_> {
     fn visit_id(&mut self, id: NodeId) {
         self.try_replace_id(id);
     }
diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs
index 8747e624a4a9e..58a1192bbb853 100644
--- a/compiler/rustc_ast_lowering/src/expr.rs
+++ b/compiler/rustc_ast_lowering/src/expr.rs
@@ -3,12 +3,12 @@ use std::sync::Arc;
 
 use rustc_ast::ptr::P as AstP;
 use rustc_ast::*;
-use rustc_ast_pretty::pprust::expr_to_string;
 use rustc_attr_data_structures::{AttributeKind, find_attr};
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_hir as hir;
 use rustc_hir::HirId;
 use rustc_hir::def::{DefKind, Res};
+use rustc_hir::definitions::DefPathData;
 use rustc_middle::span_bug;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::errors::report_lit_error;
@@ -52,7 +52,7 @@ impl<'v> rustc_ast::visit::Visitor<'v> for WillCreateDefIdsVisitor {
     }
 }
 
-impl<'hir> LoweringContext<'_, 'hir> {
+impl<'hir> LoweringContext<'hir> {
     fn lower_exprs(&mut self, exprs: &[AstP<Expr>]) -> &'hir [hir::Expr<'hir>] {
         self.arena.alloc_from_iter(exprs.iter().map(|x| self.lower_expr_mut(x)))
     }
@@ -462,13 +462,16 @@ impl<'hir> LoweringContext<'_, 'hir> {
         let mut invalid_expr_error = |tcx: TyCtxt<'_>, span| {
             // Avoid emitting the error multiple times.
             if error.is_none() {
+                let sm = tcx.sess.source_map();
                 let mut const_args = vec![];
                 let mut other_args = vec![];
                 for (idx, arg) in args.iter().enumerate() {
-                    if legacy_args_idx.contains(&idx) {
-                        const_args.push(format!("{{ {} }}", expr_to_string(arg)));
-                    } else {
-                        other_args.push(expr_to_string(arg));
+                    if let Ok(arg) = sm.span_to_snippet(arg.span) {
+                        if legacy_args_idx.contains(&idx) {
+                            const_args.push(format!("{{ {} }}", arg));
+                        } else {
+                            other_args.push(arg);
+                        }
                     }
                 }
                 let suggestion = UseConstGenericArg {
@@ -488,7 +491,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
         for (idx, arg) in args.iter().cloned().enumerate() {
             if legacy_args_idx.contains(&idx) {
                 let node_id = self.next_node_id();
-                self.create_def(node_id, None, DefKind::AnonConst, f.span);
+                self.create_def(
+                    node_id,
+                    None,
+                    DefKind::AnonConst,
+                    DefPathData::LateAnonConst,
+                    f.span,
+                );
                 let mut visitor = WillCreateDefIdsVisitor {};
                 let const_value = if let ControlFlow::Break(span) = visitor.visit_expr(&arg) {
                     AstP(Expr {
@@ -1260,7 +1269,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         whole_span: Span,
     ) -> hir::ExprKind<'hir> {
         // Return early in case of an ordinary assignment.
-        fn is_ordinary(lower_ctx: &mut LoweringContext<'_, '_>, lhs: &Expr) -> bool {
+        fn is_ordinary(lower_ctx: &mut LoweringContext<'_>, lhs: &Expr) -> bool {
             match &lhs.kind {
                 ExprKind::Array(..)
                 | ExprKind::Struct(..)
@@ -1320,7 +1329,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
     ) -> Option<(&'a Option<AstP<QSelf>>, &'a Path)> {
         if let ExprKind::Path(qself, path) = &expr.kind {
             // Does the path resolve to something disallowed in a tuple struct/variant pattern?
-            if let Some(partial_res) = self.resolver.get_partial_res(expr.id) {
+            if let Some(partial_res) = self.get_partial_res(expr.id) {
                 if let Some(res) = partial_res.full_res()
                     && !res.expected_in_tuple_struct_pat()
                 {
@@ -1342,7 +1351,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
     ) -> Option<(&'a Option<AstP<QSelf>>, &'a Path)> {
         if let ExprKind::Path(qself, path) = &expr.kind {
             // Does the path resolve to something disallowed in a unit struct/variant pattern?
-            if let Some(partial_res) = self.resolver.get_partial_res(expr.id) {
+            if let Some(partial_res) = self.get_partial_res(expr.id) {
                 if let Some(res) = partial_res.full_res()
                     && !res.expected_in_unit_struct_pat()
                 {
diff --git a/compiler/rustc_ast_lowering/src/format.rs b/compiler/rustc_ast_lowering/src/format.rs
index 943cde90dd20b..716a356b3954d 100644
--- a/compiler/rustc_ast_lowering/src/format.rs
+++ b/compiler/rustc_ast_lowering/src/format.rs
@@ -8,7 +8,7 @@ use rustc_span::{DesugaringKind, Ident, Span, Symbol, sym};
 
 use super::LoweringContext;
 
-impl<'hir> LoweringContext<'_, 'hir> {
+impl<'hir> LoweringContext<'hir> {
     pub(crate) fn lower_format_args(&mut self, sp: Span, fmt: &FormatArgs) -> hir::ExprKind<'hir> {
         // Never call the const constructor of `fmt::Arguments` if the
         // format_args!() had any arguments _before_ flattening/inlining.
@@ -236,7 +236,7 @@ enum ArgumentType {
 ///     <core::fmt::Argument>::new_…(arg)
 /// ```
 fn make_argument<'hir>(
-    ctx: &mut LoweringContext<'_, 'hir>,
+    ctx: &mut LoweringContext<'hir>,
     sp: Span,
     arg: &'hir hir::Expr<'hir>,
     ty: ArgumentType,
@@ -285,7 +285,7 @@ fn make_argument<'hir>(
 ///     <core::fmt::rt::Count>::Implied
 /// ```
 fn make_count<'hir>(
-    ctx: &mut LoweringContext<'_, 'hir>,
+    ctx: &mut LoweringContext<'hir>,
     sp: Span,
     count: &Option<FormatCount>,
     argmap: &mut FxIndexMap<(usize, ArgumentType), Option<Span>>,
@@ -336,7 +336,7 @@ fn make_count<'hir>(
 ///     }
 /// ```
 fn make_format_spec<'hir>(
-    ctx: &mut LoweringContext<'_, 'hir>,
+    ctx: &mut LoweringContext<'hir>,
     sp: Span,
     placeholder: &FormatPlaceholder,
     argmap: &mut FxIndexMap<(usize, ArgumentType), Option<Span>>,
@@ -397,7 +397,7 @@ fn make_format_spec<'hir>(
 }
 
 fn expand_format_args<'hir>(
-    ctx: &mut LoweringContext<'_, 'hir>,
+    ctx: &mut LoweringContext<'hir>,
     macsp: Span,
     fmt: &FormatArgs,
     allow_const: bool,
diff --git a/compiler/rustc_ast_lowering/src/index.rs b/compiler/rustc_ast_lowering/src/index.rs
index 956cb580d1032..1ef64f5a3526b 100644
--- a/compiler/rustc_ast_lowering/src/index.rs
+++ b/compiler/rustc_ast_lowering/src/index.rs
@@ -381,28 +381,16 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
         })
     }
 
-    fn visit_trait_item_ref(&mut self, ii: &'hir TraitItemRef) {
-        // Do not visit the duplicate information in TraitItemRef. We want to
-        // map the actual nodes, not the duplicate ones in the *Ref.
-        let TraitItemRef { id, ident: _, kind: _, span: _ } = *ii;
-
-        self.visit_nested_trait_item(id);
+    fn visit_trait_item_ref(&mut self, id: &'hir TraitItemId) {
+        self.visit_nested_trait_item(*id);
     }
 
-    fn visit_impl_item_ref(&mut self, ii: &'hir ImplItemRef) {
-        // Do not visit the duplicate information in ImplItemRef. We want to
-        // map the actual nodes, not the duplicate ones in the *Ref.
-        let ImplItemRef { id, ident: _, kind: _, span: _, trait_item_def_id: _ } = *ii;
-
-        self.visit_nested_impl_item(id);
+    fn visit_impl_item_ref(&mut self, id: &'hir ImplItemId) {
+        self.visit_nested_impl_item(*id);
     }
 
-    fn visit_foreign_item_ref(&mut self, fi: &'hir ForeignItemRef) {
-        // Do not visit the duplicate information in ForeignItemRef. We want to
-        // map the actual nodes, not the duplicate ones in the *Ref.
-        let ForeignItemRef { id, ident: _, span: _ } = *fi;
-
-        self.visit_nested_foreign_item(id);
+    fn visit_foreign_item_ref(&mut self, id: &'hir ForeignItemId) {
+        self.visit_nested_foreign_item(*id);
     }
 
     fn visit_where_predicate(&mut self, predicate: &'hir WherePredicate<'hir>) {
diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs
index bdcb750ba260a..caa6f24a6abdf 100644
--- a/compiler/rustc_ast_lowering/src/item.rs
+++ b/compiler/rustc_ast_lowering/src/item.rs
@@ -1,18 +1,16 @@
 use rustc_abi::ExternAbi;
 use rustc_ast::ptr::P;
-use rustc_ast::visit::AssocCtxt;
 use rustc_ast::*;
 use rustc_attr_data_structures::{AttributeKind, find_attr};
 use rustc_errors::{E0570, ErrorGuaranteed, struct_span_code_err};
 use rustc_hir::def::{DefKind, PerNS, Res};
-use rustc_hir::def_id::{CRATE_DEF_ID, LocalDefId};
+use rustc_hir::def_id::CRATE_DEF_ID;
 use rustc_hir::{self as hir, HirId, LifetimeSource, PredicateOrigin};
-use rustc_index::{IndexSlice, IndexVec};
 use rustc_middle::span_bug;
 use rustc_middle::ty::{ResolverAstLowering, TyCtxt};
 use rustc_span::edit_distance::find_best_match_for_name;
-use rustc_span::{DUMMY_SP, DesugaringKind, Ident, Span, Symbol, kw, sym};
-use smallvec::{SmallVec, smallvec};
+use rustc_span::{DesugaringKind, Ident, Span, Symbol, kw, sym};
+use smallvec::SmallVec;
 use thin_vec::ThinVec;
 use tracing::instrument;
 
@@ -22,15 +20,14 @@ use super::errors::{
 };
 use super::stability::{enabled_names, gate_unstable_abi};
 use super::{
-    AstOwner, FnDeclKind, ImplTraitContext, ImplTraitPosition, LoweringContext, ParamMode,
+    FnDeclKind, ImplTraitContext, ImplTraitPosition, LoweringContext, ParamMode,
     ResolverAstLoweringExt,
 };
 
-pub(super) struct ItemLowerer<'a, 'hir> {
+pub(super) struct ItemLowerer<'hir> {
     pub(super) tcx: TyCtxt<'hir>,
-    pub(super) resolver: &'a mut ResolverAstLowering,
-    pub(super) ast_index: &'a IndexSlice<LocalDefId, AstOwner<'a>>,
-    pub(super) owners: &'a mut IndexVec<LocalDefId, hir::MaybeOwner<'hir>>,
+    pub(super) resolver: &'hir ResolverAstLowering,
+    pub(super) next_node_id: NodeId,
 }
 
 /// When we have a ty alias we *may* have two where clauses. To give the best diagnostics, we set the span
@@ -54,55 +51,51 @@ fn add_ty_alias_where_clause(
     generics.where_clause.span = where_clause.span;
 }
 
-impl<'a, 'hir> ItemLowerer<'a, 'hir> {
+impl<'hir> ItemLowerer<'hir> {
     fn with_lctx(
         &mut self,
         owner: NodeId,
-        f: impl FnOnce(&mut LoweringContext<'_, 'hir>) -> hir::OwnerNode<'hir>,
-    ) {
-        let mut lctx = LoweringContext::new(self.tcx, self.resolver);
-        lctx.with_hir_id_owner(owner, |lctx| f(lctx));
-
-        for (def_id, info) in lctx.children {
-            let owner = self.owners.ensure_contains_elem(def_id, || hir::MaybeOwner::Phantom);
-            assert!(
-                matches!(owner, hir::MaybeOwner::Phantom),
-                "duplicate copy of {def_id:?} in lctx.children"
-            );
-            *owner = info;
-        }
+        f: impl FnOnce(&mut LoweringContext<'hir>) -> hir::OwnerNode<'hir>,
+    ) -> hir::MaybeOwner<'hir> {
+        let mut lctx = LoweringContext::new(self.tcx, self.resolver, owner, self.next_node_id);
+
+        let item = f(&mut lctx);
+        debug_assert_eq!(lctx.current_hir_id_owner, item.def_id());
+
+        let info = lctx.make_owner_info(item);
+
+        hir::MaybeOwner::Owner(lctx.arena.alloc(info))
     }
 
-    pub(super) fn lower_node(&mut self, def_id: LocalDefId) {
-        let owner = self.owners.ensure_contains_elem(def_id, || hir::MaybeOwner::Phantom);
-        if let hir::MaybeOwner::Phantom = owner {
-            let node = self.ast_index[def_id];
-            match node {
-                AstOwner::NonOwner => {}
-                AstOwner::Crate(c) => {
-                    assert_eq!(self.resolver.node_id_to_def_id[&CRATE_NODE_ID], CRATE_DEF_ID);
-                    self.with_lctx(CRATE_NODE_ID, |lctx| {
-                        let module = lctx.lower_mod(&c.items, &c.spans);
-                        // FIXME(jdonszelman): is dummy span ever a problem here?
-                        lctx.lower_attrs(hir::CRATE_HIR_ID, &c.attrs, DUMMY_SP);
-                        hir::OwnerNode::Crate(module)
-                    })
-                }
-                AstOwner::Item(item) => {
-                    self.with_lctx(item.id, |lctx| hir::OwnerNode::Item(lctx.lower_item(item)))
-                }
-                AstOwner::AssocItem(item, ctxt) => {
-                    self.with_lctx(item.id, |lctx| lctx.lower_assoc_item(item, ctxt))
-                }
-                AstOwner::ForeignItem(item) => self.with_lctx(item.id, |lctx| {
-                    hir::OwnerNode::ForeignItem(lctx.lower_foreign_item(item))
-                }),
-            }
-        }
+    #[instrument(level = "debug", skip(self, c))]
+    pub(super) fn lower_crate(&mut self, c: &Crate) -> hir::MaybeOwner<'hir> {
+        debug_assert_eq!(self.resolver.node_id_to_def_id[&CRATE_NODE_ID], CRATE_DEF_ID);
+        self.with_lctx(CRATE_NODE_ID, |lctx| {
+            let module = lctx.lower_mod(&c.items, &c.spans);
+            lctx.lower_attrs(hir::CRATE_HIR_ID, &c.attrs, c.spans.inner_span);
+            hir::OwnerNode::Crate(module)
+        })
+    }
+
+    #[instrument(level = "debug", skip(self))]
+    pub(super) fn lower_item(&mut self, item: &Item) -> hir::MaybeOwner<'hir> {
+        self.with_lctx(item.id, |lctx| hir::OwnerNode::Item(lctx.lower_item(item)))
+    }
+
+    pub(super) fn lower_trait_item(&mut self, item: &AssocItem) -> hir::MaybeOwner<'hir> {
+        self.with_lctx(item.id, |lctx| hir::OwnerNode::TraitItem(lctx.lower_trait_item(item)))
+    }
+
+    pub(super) fn lower_impl_item(&mut self, item: &AssocItem) -> hir::MaybeOwner<'hir> {
+        self.with_lctx(item.id, |lctx| hir::OwnerNode::ImplItem(lctx.lower_impl_item(item)))
+    }
+
+    pub(super) fn lower_foreign_item(&mut self, item: &ForeignItem) -> hir::MaybeOwner<'hir> {
+        self.with_lctx(item.id, |lctx| hir::OwnerNode::ForeignItem(lctx.lower_foreign_item(item)))
     }
 }
 
-impl<'hir> LoweringContext<'_, 'hir> {
+impl<'hir> LoweringContext<'hir> {
     pub(super) fn lower_mod(
         &mut self,
         items: &[P<Item>],
@@ -113,37 +106,22 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 inner_span: self.lower_span(spans.inner_span),
                 inject_use_span: self.lower_span(spans.inject_use_span),
             },
-            item_ids: self.arena.alloc_from_iter(items.iter().flat_map(|x| self.lower_item_ref(x))),
+            item_ids: self.arena.alloc_from_iter(items.iter().map(|x| self.lower_item_ref(x))),
         })
     }
 
-    pub(super) fn lower_item_ref(&mut self, i: &Item) -> SmallVec<[hir::ItemId; 1]> {
-        let mut node_ids = smallvec![hir::ItemId { owner_id: self.owner_id(i.id) }];
-        if let ItemKind::Use(use_tree) = &i.kind {
-            self.lower_item_id_use_tree(use_tree, &mut node_ids);
-        }
-        node_ids
-    }
-
-    fn lower_item_id_use_tree(&mut self, tree: &UseTree, vec: &mut SmallVec<[hir::ItemId; 1]>) {
-        match &tree.kind {
-            UseTreeKind::Nested { items, .. } => {
-                for &(ref nested, id) in items {
-                    vec.push(hir::ItemId { owner_id: self.owner_id(id) });
-                    self.lower_item_id_use_tree(nested, vec);
-                }
-            }
-            UseTreeKind::Simple(..) | UseTreeKind::Glob => {}
-        }
+    pub(super) fn lower_item_ref(&mut self, i: &Item) -> hir::ItemId {
+        hir::ItemId { owner_id: self.owner_id(i.id) }
     }
 
     fn lower_item(&mut self, i: &Item) -> &'hir hir::Item<'hir> {
+        let owner_id = self.current_hir_id_owner;
+        let hir_id: HirId = owner_id.into();
         let vis_span = self.lower_span(i.vis.span);
-        let hir_id = hir::HirId::make_owner(self.current_hir_id_owner.def_id);
         let attrs = self.lower_attrs(hir_id, &i.attrs, i.span);
         let kind = self.lower_item_kind(i.span, i.id, hir_id, attrs, vis_span, &i.kind);
         let item = hir::Item {
-            owner_id: hir_id.expect_owner(),
+            owner_id,
             kind,
             vis_span,
             span: self.lower_span(i.span),
@@ -393,11 +371,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         (trait_ref, lowered_ty)
                     });
 
-                let new_impl_items = self.arena.alloc_from_iter(
-                    impl_items
-                        .iter()
-                        .map(|item| self.lower_impl_item_ref(item, trait_ref.is_some())),
-                );
+                let new_impl_items = self
+                    .arena
+                    .alloc_from_iter(impl_items.iter().map(|item| self.lower_impl_item_ref(item)));
 
                 // `defaultness.has_value()` is never called for an `impl`, always `true` in order
                 // to not cause an assertion failure inside the `lower_defaultness` function.
@@ -628,21 +604,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }
     }
 
-    fn lower_assoc_item(&mut self, item: &AssocItem, ctxt: AssocCtxt) -> hir::OwnerNode<'hir> {
-        // Evaluate with the lifetimes in `params` in-scope.
-        // This is used to track which lifetimes have already been defined,
-        // and which need to be replicated when lowering an async fn.
-        match ctxt {
-            AssocCtxt::Trait => hir::OwnerNode::TraitItem(self.lower_trait_item(item)),
-            AssocCtxt::Impl { of_trait } => {
-                hir::OwnerNode::ImplItem(self.lower_impl_item(item, of_trait))
-            }
-        }
-    }
-
     fn lower_foreign_item(&mut self, i: &ForeignItem) -> &'hir hir::ForeignItem<'hir> {
-        let hir_id = hir::HirId::make_owner(self.current_hir_id_owner.def_id);
-        let owner_id = hir_id.expect_owner();
+        let owner_id = self.current_hir_id_owner;
+        let hir_id: HirId = owner_id.into();
         let attrs = self.lower_attrs(hir_id, &i.attrs, i.span);
         let (ident, kind) = match &i.kind {
             ForeignItemKind::Fn(box Fn { sig, ident, generics, define_opaque, .. }) => {
@@ -706,14 +670,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
         self.arena.alloc(item)
     }
 
-    fn lower_foreign_item_ref(&mut self, i: &ForeignItem) -> hir::ForeignItemRef {
-        hir::ForeignItemRef {
-            id: hir::ForeignItemId { owner_id: self.owner_id(i.id) },
-            // `unwrap` is safe because `ForeignItemKind::MacCall` is the only foreign item kind
-            // without an identifier and it cannot reach here.
-            ident: self.lower_ident(i.kind.ident().unwrap()),
-            span: self.lower_span(i.span),
-        }
+    fn lower_foreign_item_ref(&mut self, i: &ForeignItem) -> hir::ForeignItemId {
+        hir::ForeignItemId { owner_id: self.owner_id(i.id) }
     }
 
     fn lower_variant(&mut self, item_kind: &ItemKind, v: &Variant) -> hir::Variant<'hir> {
@@ -819,9 +777,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
     }
 
     fn lower_trait_item(&mut self, i: &AssocItem) -> &'hir hir::TraitItem<'hir> {
-        let hir_id = hir::HirId::make_owner(self.current_hir_id_owner.def_id);
+        let trait_item_def_id = self.current_hir_id_owner;
+        let hir_id: HirId = trait_item_def_id.into();
         let attrs = self.lower_attrs(hir_id, &i.attrs, i.span);
-        let trait_item_def_id = hir_id.expect_owner();
 
         let (ident, generics, kind, has_default) = match &i.kind {
             AssocItemKind::Const(box ConstItem {
@@ -972,32 +930,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
         self.arena.alloc(item)
     }
 
-    fn lower_trait_item_ref(&mut self, i: &AssocItem) -> hir::TraitItemRef {
-        let (ident, kind) = match &i.kind {
-            AssocItemKind::Const(box ConstItem { ident, .. }) => {
-                (*ident, hir::AssocItemKind::Const)
-            }
-            AssocItemKind::Type(box TyAlias { ident, .. }) => (*ident, hir::AssocItemKind::Type),
-            AssocItemKind::Fn(box Fn { ident, sig, .. }) => {
-                (*ident, hir::AssocItemKind::Fn { has_self: sig.decl.has_self() })
-            }
-            AssocItemKind::Delegation(box delegation) => (
-                delegation.ident,
-                hir::AssocItemKind::Fn {
-                    has_self: self.delegatee_is_method(i.id, delegation.id, i.span, false),
-                },
-            ),
-            AssocItemKind::MacCall(..) | AssocItemKind::DelegationMac(..) => {
-                panic!("macros should have been expanded by now")
-            }
-        };
-        let id = hir::TraitItemId { owner_id: self.owner_id(i.id) };
-        hir::TraitItemRef {
-            id,
-            ident: self.lower_ident(ident),
-            span: self.lower_span(i.span),
-            kind,
-        }
+    fn lower_trait_item_ref(&mut self, i: &AssocItem) -> hir::TraitItemId {
+        hir::TraitItemId { owner_id: self.owner_id(i.id) }
     }
 
     /// Construct `ExprKind::Err` for the given `span`.
@@ -1005,15 +939,16 @@ impl<'hir> LoweringContext<'_, 'hir> {
         self.expr(span, hir::ExprKind::Err(guar))
     }
 
-    fn lower_impl_item(
-        &mut self,
-        i: &AssocItem,
-        is_in_trait_impl: bool,
-    ) -> &'hir hir::ImplItem<'hir> {
+    fn lower_impl_item(&mut self, i: &AssocItem) -> &'hir hir::ImplItem<'hir> {
+        let owner_id = self.current_hir_id_owner;
+        let hir_id: HirId = owner_id.into();
+        let parent_id = self.tcx.local_parent(owner_id.def_id);
+        let is_in_trait_impl =
+            matches!(self.tcx.def_kind(parent_id), DefKind::Impl { of_trait: true });
+
         // Since `default impl` is not yet implemented, this is always true in impls.
         let has_value = true;
         let (defaultness, _) = self.lower_defaultness(i.kind.defaultness(), has_value);
-        let hir_id = hir::HirId::make_owner(self.current_hir_id_owner.def_id);
         let attrs = self.lower_attrs(hir_id, &i.attrs, i.span);
 
         let (ident, (generics, kind)) = match &i.kind {
@@ -1120,7 +1055,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         };
 
         let item = hir::ImplItem {
-            owner_id: hir_id.expect_owner(),
+            owner_id,
             ident: self.lower_ident(ident),
             generics,
             kind,
@@ -1128,41 +1063,16 @@ impl<'hir> LoweringContext<'_, 'hir> {
             span: self.lower_span(i.span),
             defaultness,
             has_delayed_lints: !self.delayed_lints.is_empty(),
-        };
-        self.arena.alloc(item)
-    }
-
-    fn lower_impl_item_ref(&mut self, i: &AssocItem, is_in_trait_impl: bool) -> hir::ImplItemRef {
-        hir::ImplItemRef {
-            id: hir::ImplItemId { owner_id: self.owner_id(i.id) },
-            // `unwrap` is safe because `AssocItemKind::{MacCall,DelegationMac}` are the only
-            // assoc item kinds without an identifier and they cannot reach here.
-            ident: self.lower_ident(i.kind.ident().unwrap()),
-            span: self.lower_span(i.span),
-            kind: match &i.kind {
-                AssocItemKind::Const(..) => hir::AssocItemKind::Const,
-                AssocItemKind::Type(..) => hir::AssocItemKind::Type,
-                AssocItemKind::Fn(box Fn { sig, .. }) => {
-                    hir::AssocItemKind::Fn { has_self: sig.decl.has_self() }
-                }
-                AssocItemKind::Delegation(box delegation) => hir::AssocItemKind::Fn {
-                    has_self: self.delegatee_is_method(
-                        i.id,
-                        delegation.id,
-                        i.span,
-                        is_in_trait_impl,
-                    ),
-                },
-                AssocItemKind::MacCall(..) | AssocItemKind::DelegationMac(..) => {
-                    panic!("macros should have been expanded by now")
-                }
-            },
             trait_item_def_id: self
-                .resolver
                 .get_partial_res(i.id)
                 .map(|r| r.expect_full_res().opt_def_id())
                 .unwrap_or(None),
-        }
+        };
+        self.arena.alloc(item)
+    }
+
+    fn lower_impl_item_ref(&mut self, i: &AssocItem) -> hir::ImplItemId {
+        hir::ImplItemId { owner_id: self.owner_id(i.id) }
     }
 
     fn lower_defaultness(
@@ -1396,7 +1306,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
     pub(crate) fn lower_coroutine_body_with_moved_arguments(
         &mut self,
         decl: &FnDecl,
-        lower_body: impl FnOnce(&mut LoweringContext<'_, 'hir>) -> hir::Expr<'hir>,
+        lower_body: impl FnOnce(&mut LoweringContext<'hir>) -> hir::Expr<'hir>,
         fn_decl_span: Span,
         body_span: Span,
         coroutine_kind: CoroutineKind,
@@ -1533,7 +1443,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             parameters.push(new_parameter);
         }
 
-        let mkbody = |this: &mut LoweringContext<'_, 'hir>| {
+        let mkbody = |this: &mut LoweringContext<'hir>| {
             // Create a block from the user's function body:
             let user_body = lower_body(this);
 
@@ -1735,11 +1645,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             };
             let compute_is_param = || {
                 // Check if the where clause type is a plain type parameter.
-                match self
-                    .resolver
-                    .get_partial_res(bound_pred.bounded_ty.id)
-                    .and_then(|r| r.full_res())
-                {
+                match self.get_partial_res(bound_pred.bounded_ty.id).and_then(|r| r.full_res()) {
                     Some(Res::Def(DefKind::TyParam, def_id))
                         if bound_pred.bound_generic_params.is_empty() =>
                     {
@@ -1806,7 +1712,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
         // Introduce extra lifetimes if late resolution tells us to.
         let extra_lifetimes = self.resolver.extra_lifetime_params(parent_node_id);
-        params.extend(extra_lifetimes.into_iter().filter_map(|(ident, node_id, res)| {
+        params.extend(extra_lifetimes.into_iter().filter_map(|&(ident, node_id, res)| {
             self.lifetime_res_to_generic_param(
                 ident,
                 node_id,
@@ -1848,7 +1754,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             return;
         };
         let define_opaque = define_opaque.iter().filter_map(|(id, path)| {
-            let res = self.resolver.get_partial_res(*id);
+            let res = self.get_partial_res(*id);
             let Some(did) = res.and_then(|res| res.expect_full_res().opt_def_id()) else {
                 self.dcx().span_delayed_bug(path.span, "should have errored in resolve");
                 return None;
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 0706bdb119f01..c363ad58d195b 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -40,30 +40,33 @@
 
 use std::sync::Arc;
 
+use rustc_ast::mut_visit::{self, MutVisitor};
 use rustc_ast::node_id::NodeMap;
+use rustc_ast::ptr::P;
 use rustc_ast::{self as ast, *};
 use rustc_attr_parsing::{AttributeParser, OmitDoc};
-use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::sorted_map::SortedMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_data_structures::sync::spawn;
+use rustc_data_structures::steal::Steal;
 use rustc_data_structures::tagged_ptr::TaggedRef;
+use rustc_data_structures::unord::ExtendUnord;
 use rustc_errors::{DiagArgFromDisplay, DiagCtxtHandle};
 use rustc_hir::def::{DefKind, LifetimeRes, Namespace, PartialRes, PerNS, Res};
-use rustc_hir::def_id::{CRATE_DEF_ID, LOCAL_CRATE, LocalDefId};
+use rustc_hir::def_id::{LOCAL_CRATE, LocalDefId, LocalDefIdMap};
+use rustc_hir::definitions::{DefPathData, DisambiguatorState};
 use rustc_hir::lints::DelayedLint;
 use rustc_hir::{
     self as hir, AngleBrackets, ConstArg, GenericArg, HirId, ItemLocalMap, LangItem,
     LifetimeSource, LifetimeSyntax, ParamName, TraitCandidate,
 };
-use rustc_index::{Idx, IndexSlice, IndexVec};
+use rustc_index::{Idx, IndexVec};
 use rustc_macros::extension;
 use rustc_middle::span_bug;
 use rustc_middle::ty::{ResolverAstLowering, TyCtxt};
 use rustc_session::parse::add_feature_diagnostics;
 use rustc_span::symbol::{Ident, Symbol, kw, sym};
 use rustc_span::{DUMMY_SP, DesugaringKind, Span};
-use smallvec::SmallVec;
+use smallvec::{SmallVec, smallvec};
 use thin_vec::ThinVec;
 use tracing::{debug, instrument, trace};
 
@@ -89,9 +92,10 @@ pub mod stability;
 
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
 
-struct LoweringContext<'a, 'hir> {
+struct LoweringContext<'hir> {
     tcx: TyCtxt<'hir>,
-    resolver: &'a mut ResolverAstLowering,
+    resolver: &'hir ResolverAstLowering,
+    disambiguator: DisambiguatorState,
 
     /// Used to allocate HIR nodes.
     arena: &'hir hir::Arena<'hir>,
@@ -103,7 +107,7 @@ struct LoweringContext<'a, 'hir> {
     /// Attributes inside the owner being lowered.
     attrs: SortedMap<hir::ItemLocalId, &'hir [hir::Attribute]>,
     /// Collect items that were created by lowering the current owner.
-    children: Vec<(LocalDefId, hir::MaybeOwner<'hir>)>,
+    children: LocalDefIdMap<hir::MaybeOwner<'hir>>,
 
     contract_ensures: Option<(Span, Ident, HirId)>,
 
@@ -124,7 +128,7 @@ struct LoweringContext<'a, 'hir> {
 
     current_hir_id_owner: hir::OwnerId,
     item_local_id_counter: hir::ItemLocalId,
-    trait_map: ItemLocalMap<Box<[TraitCandidate]>>,
+    trait_map: ItemLocalMap<&'hir [TraitCandidate]>,
 
     impl_trait_defs: Vec<hir::GenericParam<'hir>>,
     impl_trait_bounds: Vec<hir::WherePredicate<'hir>>,
@@ -134,6 +138,14 @@ struct LoweringContext<'a, 'hir> {
     /// NodeIds that are lowered inside the current HIR owner. Only used for duplicate lowering check.
     #[cfg(debug_assertions)]
     node_id_to_local_id: NodeMap<hir::ItemLocalId>,
+    /// The `NodeId` space is split in two.
+    /// `0..resolver.next_node_id` are created by the resolver on the AST.
+    /// The higher part `resolver.next_node_id..next_node_id` are created during lowering.
+    next_node_id: NodeId,
+    /// Maps the `NodeId`s created during lowering to `LocalDefId`s.
+    node_id_to_def_id: NodeMap<LocalDefId>,
+    /// Overlay over resolver's `partial_res_map` used by delegation.
+    partial_res_overrides: NodeMap<PartialRes>,
 
     allow_try_trait: Arc<[Symbol]>,
     allow_gen_future: Arc<[Symbol]>,
@@ -147,27 +159,37 @@ struct LoweringContext<'a, 'hir> {
     attribute_parser: AttributeParser<'hir>,
 }
 
-impl<'a, 'hir> LoweringContext<'a, 'hir> {
-    fn new(tcx: TyCtxt<'hir>, resolver: &'a mut ResolverAstLowering) -> Self {
+impl<'hir> LoweringContext<'hir> {
+    fn new(
+        tcx: TyCtxt<'hir>,
+        resolver: &'hir ResolverAstLowering,
+        owner: NodeId,
+        next_node_id: NodeId,
+    ) -> Self {
         let registered_tools = tcx.registered_tools(()).iter().map(|x| x.name).collect();
+        let current_hir_id_owner = hir::OwnerId { def_id: resolver.node_id_to_def_id[&owner] };
         Self {
             // Pseudo-globals.
             tcx,
             resolver,
+            disambiguator: DisambiguatorState::new(),
             arena: tcx.hir_arena,
 
             // HirId handling.
             bodies: Vec::new(),
             define_opaque: None,
             attrs: SortedMap::default(),
-            children: Vec::default(),
+            children: LocalDefIdMap::default(),
             contract_ensures: None,
-            current_hir_id_owner: hir::CRATE_OWNER_ID,
-            item_local_id_counter: hir::ItemLocalId::ZERO,
+            current_hir_id_owner,
+            item_local_id_counter: hir::ItemLocalId::new(1),
             ident_and_label_to_local_id: Default::default(),
             #[cfg(debug_assertions)]
-            node_id_to_local_id: Default::default(),
+            node_id_to_local_id: [(owner, hir::ItemLocalId::ZERO)].into_iter().collect(),
             trait_map: Default::default(),
+            next_node_id,
+            node_id_to_def_id: NodeMap::default(),
+            partial_res_overrides: NodeMap::default(),
 
             // Lowering state.
             catch_scope: None,
@@ -245,10 +267,6 @@ impl ResolverAstLowering {
         None
     }
 
-    fn get_partial_res(&self, id: NodeId) -> Option<PartialRes> {
-        self.partial_res_map.get(&id).copied()
-    }
-
     /// Obtains per-namespace resolutions for `use` statement with the given `NodeId`.
     fn get_import_res(&self, id: NodeId) -> PerNS<Option<Res<NodeId>>> {
         self.import_res_map.get(&id).copied().unwrap_or_default()
@@ -271,8 +289,8 @@ impl ResolverAstLowering {
     ///
     /// The extra lifetimes that appear from the parenthesized `Fn`-trait desugaring
     /// should appear at the enclosing `PolyTraitRef`.
-    fn extra_lifetime_params(&mut self, id: NodeId) -> Vec<(Ident, NodeId, LifetimeRes)> {
-        self.extra_lifetime_params_map.get(&id).cloned().unwrap_or_default()
+    fn extra_lifetime_params(&self, id: NodeId) -> &[(Ident, NodeId, LifetimeRes)] {
+        self.extra_lifetime_params_map.get(&id).map_or(&[], |v| &v[..])
     }
 }
 
@@ -372,119 +390,200 @@ enum FnDeclKind {
     Impl,
 }
 
-#[derive(Copy, Clone)]
-enum AstOwner<'a> {
-    NonOwner,
-    Crate(&'a ast::Crate),
-    Item(&'a ast::Item),
-    AssocItem(&'a ast::AssocItem, visit::AssocCtxt),
-    ForeignItem(&'a ast::ForeignItem),
-}
+pub fn index_ast<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    (): (),
+) -> (IndexVec<LocalDefId, Steal<AstOwner>>, NodeId) {
+    // Queries that borrow `resolver_for_lowering`.
+    tcx.ensure_done().output_filenames(());
+    tcx.ensure_done().early_lint_checks(());
+    tcx.ensure_done().get_lang_items(());
+    tcx.ensure_done().debugger_visualizers(LOCAL_CRATE);
+
+    let (resolver, krate) = tcx.resolver_for_lowering();
+    let mut krate = krate.steal();
+
+    let mut indexer = Indexer {
+        node_id_to_def_id: &resolver.node_id_to_def_id,
+        index: IndexVec::new(),
+        next_node_id: resolver.next_node_id,
+    };
+    indexer.visit_crate(&mut krate);
+    indexer.insert(CRATE_NODE_ID, AstOwner::Crate(P(krate)));
+    return (indexer.index, indexer.next_node_id);
 
-fn index_crate<'a>(
-    node_id_to_def_id: &NodeMap<LocalDefId>,
-    krate: &'a Crate,
-) -> IndexVec<LocalDefId, AstOwner<'a>> {
-    let mut indexer = Indexer { node_id_to_def_id, index: IndexVec::new() };
-    *indexer.index.ensure_contains_elem(CRATE_DEF_ID, || AstOwner::NonOwner) =
-        AstOwner::Crate(krate);
-    visit::walk_crate(&mut indexer, krate);
-    return indexer.index;
-
-    struct Indexer<'s, 'a> {
+    struct Indexer<'s> {
         node_id_to_def_id: &'s NodeMap<LocalDefId>,
-        index: IndexVec<LocalDefId, AstOwner<'a>>,
+        index: IndexVec<LocalDefId, Steal<AstOwner>>,
+        next_node_id: NodeId,
     }
 
-    impl<'a> visit::Visitor<'a> for Indexer<'_, 'a> {
-        fn visit_attribute(&mut self, _: &'a Attribute) {
+    impl Indexer<'_> {
+        fn insert(&mut self, id: NodeId, node: AstOwner) {
+            let def_id = self.node_id_to_def_id[&id];
+            self.index.ensure_contains_elem(def_id, || Steal::new(AstOwner::NonOwner));
+            self.index[def_id] = Steal::new(node);
+        }
+
+        fn make_dummy<K>(
+            &mut self,
+            id: NodeId,
+            span: Span,
+            dummy: impl FnOnce(P<MacCall>) -> K,
+        ) -> P<Item<K>> {
+            use rustc_ast::token::Delimiter;
+            use rustc_ast::tokenstream::{DelimSpan, TokenStream};
+            use thin_vec::thin_vec;
+
+            P(Item {
+                attrs: AttrVec::default(),
+                id,
+                span,
+                vis: Visibility { kind: VisibilityKind::Public, span, tokens: None },
+                // Lacking a better choice, we replace the contents with a macro call.
+                // Unexpanded macros should never reach lowering, so this is not confusing.
+                kind: dummy(P(MacCall {
+                    path: Path { span, segments: thin_vec![], tokens: None },
+                    args: P(DelimArgs {
+                        dspan: DelimSpan::from_single(span),
+                        delim: Delimiter::Parenthesis,
+                        tokens: TokenStream::new(Vec::new()),
+                    }),
+                })),
+                tokens: None,
+            })
+        }
+
+        fn replace_with_dummy<K>(
+            &mut self,
+            item: &mut ast::Item<K>,
+            dummy: impl FnOnce(P<MacCall>) -> K,
+            node: impl FnOnce(P<Item<K>>) -> AstOwner,
+        ) {
+            let dummy = self.make_dummy(item.id, item.span, dummy);
+            let item = std::mem::replace(item, *dummy);
+            self.insert(item.id, node(P(item)));
+        }
+
+        #[tracing::instrument(level = "trace", skip(self))]
+        fn visit_item_id_use_tree(
+            &mut self,
+            tree: &UseTree,
+            parent: LocalDefId,
+            items: &mut SmallVec<[P<Item>; 1]>,
+        ) {
+            match tree.kind {
+                UseTreeKind::Glob | UseTreeKind::Simple(_) => {}
+                UseTreeKind::Nested { items: ref nested_vec, span } => {
+                    for &(ref nested, id) in nested_vec {
+                        self.insert(id, AstOwner::Synthetic(parent));
+                        items.push(self.make_dummy(id, span, ItemKind::MacCall));
+
+                        let def_id = self.node_id_to_def_id[&id];
+                        self.visit_item_id_use_tree(nested, def_id, items);
+                    }
+                }
+            }
+        }
+    }
+
+    impl MutVisitor for Indexer<'_> {
+        fn visit_attribute(&mut self, _: &mut Attribute) {
             // We do not want to lower expressions that appear in attributes,
             // as they are not accessible to the rest of the HIR.
         }
 
-        fn visit_item(&mut self, item: &'a ast::Item) {
+        fn flat_map_item(&mut self, mut item: P<Item>) -> SmallVec<[P<Item>; 1]> {
             let def_id = self.node_id_to_def_id[&item.id];
-            *self.index.ensure_contains_elem(def_id, || AstOwner::NonOwner) = AstOwner::Item(item);
-            visit::walk_item(self, item)
+            mut_visit::walk_item(self, &mut *item);
+            let dummy = self.make_dummy(item.id, item.span, ItemKind::MacCall);
+            let mut items = smallvec![dummy];
+            if let ItemKind::Use(ref use_tree) = item.kind {
+                self.visit_item_id_use_tree(use_tree, def_id, &mut items);
+            }
+            self.insert(item.id, AstOwner::Item(item));
+            items
         }
 
-        fn visit_assoc_item(&mut self, item: &'a ast::AssocItem, ctxt: visit::AssocCtxt) {
-            let def_id = self.node_id_to_def_id[&item.id];
-            *self.index.ensure_contains_elem(def_id, || AstOwner::NonOwner) =
-                AstOwner::AssocItem(item, ctxt);
-            visit::walk_assoc_item(self, item, ctxt);
+        fn flat_map_stmt(&mut self, stmt: Stmt) -> SmallVec<[Stmt; 1]> {
+            let Stmt { id, span, kind } = stmt;
+            let mut id = Some(id);
+            mut_visit::walk_flat_map_stmt_kind(self, kind)
+                .into_iter()
+                .map(|kind| {
+                    let id = id.take().unwrap_or_else(|| {
+                        let next = self.next_node_id;
+                        self.next_node_id.increment_by(1);
+                        next
+                    });
+                    Stmt { id, kind, span }
+                })
+                .collect()
         }
 
-        fn visit_foreign_item(&mut self, item: &'a ast::ForeignItem) {
-            let def_id = self.node_id_to_def_id[&item.id];
-            *self.index.ensure_contains_elem(def_id, || AstOwner::NonOwner) =
-                AstOwner::ForeignItem(item);
-            visit::walk_item(self, item);
+        fn visit_assoc_item(&mut self, item: &mut AssocItem, ctxt: visit::AssocCtxt) {
+            mut_visit::walk_assoc_item(self, item, ctxt);
+            match ctxt {
+                visit::AssocCtxt::Trait => {
+                    self.replace_with_dummy(item, AssocItemKind::MacCall, AstOwner::TraitItem)
+                }
+                visit::AssocCtxt::Impl { .. } => {
+                    self.replace_with_dummy(item, AssocItemKind::MacCall, AstOwner::ImplItem)
+                }
+            }
         }
-    }
-}
-
-/// Compute the hash for the HIR of the full crate.
-/// This hash will then be part of the crate_hash which is stored in the metadata.
-fn compute_hir_hash(
-    tcx: TyCtxt<'_>,
-    owners: &IndexSlice<LocalDefId, hir::MaybeOwner<'_>>,
-) -> Fingerprint {
-    let mut hir_body_nodes: Vec<_> = owners
-        .iter_enumerated()
-        .filter_map(|(def_id, info)| {
-            let info = info.as_owner()?;
-            let def_path_hash = tcx.hir_def_path_hash(def_id);
-            Some((def_path_hash, info))
-        })
-        .collect();
-    hir_body_nodes.sort_unstable_by_key(|bn| bn.0);
 
-    tcx.with_stable_hashing_context(|mut hcx| {
-        let mut stable_hasher = StableHasher::new();
-        hir_body_nodes.hash_stable(&mut hcx, &mut stable_hasher);
-        stable_hasher.finish()
-    })
+        fn visit_foreign_item(&mut self, item: &mut ForeignItem) {
+            mut_visit::walk_item(self, item);
+            self.replace_with_dummy(item, ForeignItemKind::MacCall, AstOwner::ForeignItem);
+        }
+    }
 }
 
-pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> hir::Crate<'_> {
-    let sess = tcx.sess;
+#[instrument(level = "trace", skip(tcx))]
+pub fn lower_to_hir(tcx: TyCtxt<'_>, def_id: LocalDefId) -> hir::MaybeOwner<'_> {
     // Queries that borrow `resolver_for_lowering`.
     tcx.ensure_done().output_filenames(());
     tcx.ensure_done().early_lint_checks(());
     tcx.ensure_done().debugger_visualizers(LOCAL_CRATE);
     tcx.ensure_done().get_lang_items(());
-    let (mut resolver, krate) = tcx.resolver_for_lowering().steal();
-
-    let ast_index = index_crate(&resolver.node_id_to_def_id, &krate);
-    let mut owners = IndexVec::from_fn_n(
-        |_| hir::MaybeOwner::Phantom,
-        tcx.definitions_untracked().def_index_count(),
-    );
-
-    let mut lowerer = item::ItemLowerer {
-        tcx,
-        resolver: &mut resolver,
-        ast_index: &ast_index,
-        owners: &mut owners,
+    let (resolver, _) = tcx.resolver_for_lowering();
+    let (ast_index, next_node_id) = tcx.index_ast(());
+    let node = ast_index.get(def_id).map(Steal::steal);
+
+    let mut item_lowerer = item::ItemLowerer { tcx, resolver, next_node_id: *next_node_id };
+
+    // The item existed in the AST.
+    let parent_id = match node.as_ref() {
+        Some(AstOwner::Crate(c)) => return item_lowerer.lower_crate(&c),
+        Some(AstOwner::Item(item)) => return item_lowerer.lower_item(&item),
+        Some(AstOwner::TraitItem(item)) => {
+            return item_lowerer.lower_trait_item(&item);
+        }
+        Some(AstOwner::ImplItem(item)) => {
+            return item_lowerer.lower_impl_item(&item);
+        }
+        Some(AstOwner::ForeignItem(item)) => return item_lowerer.lower_foreign_item(&item),
+        Some(AstOwner::Synthetic(parent_id)) => *parent_id,
+        Some(AstOwner::NonOwner) | None => tcx.local_parent(def_id),
     };
-    for def_id in ast_index.indices() {
-        lowerer.lower_node(def_id);
-    }
 
-    drop(ast_index);
+    tcx.sess.time("drop_ast", || std::mem::drop(node));
 
-    // Drop AST to free memory. It can be expensive so try to drop it on a separate thread.
-    let prof = sess.prof.clone();
-    spawn(move || {
-        let _timer = prof.verbose_generic_activity("drop_ast");
-        drop(krate);
-    });
+    // The item did not exist in the AST, it was created by its parent.
+    let mut parent_info = tcx.lower_to_hir(parent_id);
+    if let hir::MaybeOwner::NonOwner(hir_id) = parent_info {
+        parent_info = tcx.lower_to_hir(hir_id.owner);
+    }
 
-    // Don't hash unless necessary, because it's expensive.
-    let opt_hir_hash =
-        if tcx.needs_crate_hash() { Some(compute_hir_hash(tcx, &owners)) } else { None };
-    hir::Crate { owners, opt_hir_hash }
+    let parent_info = parent_info.unwrap();
+    *parent_info.children.get(&def_id).unwrap_or_else(|| {
+        panic!(
+            "{:?} does not appear in children of {:?}",
+            def_id,
+            parent_info.nodes.node().def_id()
+        )
+    })
 }
 
 #[derive(Copy, Clone, PartialEq, Debug)]
@@ -514,12 +613,13 @@ enum GenericArgsMode {
     Silence,
 }
 
-impl<'a, 'hir> LoweringContext<'a, 'hir> {
+impl<'hir> LoweringContext<'hir> {
     fn create_def(
         &mut self,
         node_id: ast::NodeId,
         name: Option<Symbol>,
         def_kind: DefKind,
+        def_path_data: DefPathData,
         span: Span,
     ) -> LocalDefId {
         let parent = self.current_hir_id_owner.def_id;
@@ -535,32 +635,43 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let def_id = self
             .tcx
             .at(span)
-            .create_def(parent, name, def_kind, None, &mut self.resolver.disambiguator)
+            .create_def(parent, name, def_kind, Some(def_path_data), &mut self.disambiguator)
             .def_id();
 
         debug!("create_def: def_id_to_node_id[{:?}] <-> {:?}", def_id, node_id);
-        self.resolver.node_id_to_def_id.insert(node_id, def_id);
+        self.node_id_to_def_id.insert(node_id, def_id);
 
         def_id
     }
 
     fn next_node_id(&mut self) -> NodeId {
-        let start = self.resolver.next_node_id;
+        let start = self.next_node_id;
         let next = start.as_u32().checked_add(1).expect("input too large; ran out of NodeIds");
-        self.resolver.next_node_id = ast::NodeId::from_u32(next);
+        self.next_node_id = ast::NodeId::from_u32(next);
         start
     }
 
     /// Given the id of some node in the AST, finds the `LocalDefId` associated with it by the name
     /// resolver (if any).
+    #[instrument(level = "trace", skip(self), ret)]
     fn opt_local_def_id(&self, node: NodeId) -> Option<LocalDefId> {
-        self.resolver.node_id_to_def_id.get(&node).copied()
+        self.node_id_to_def_id
+            .get(&node)
+            .or_else(|| self.resolver.node_id_to_def_id.get(&node))
+            .copied()
     }
 
     fn local_def_id(&self, node: NodeId) -> LocalDefId {
         self.opt_local_def_id(node).unwrap_or_else(|| panic!("no entry for node id: `{node:?}`"))
     }
 
+    fn get_partial_res(&self, id: NodeId) -> Option<PartialRes> {
+        self.partial_res_overrides
+            .get(&id)
+            .or_else(|| self.resolver.partial_res_map.get(&id))
+            .copied()
+    }
+
     /// Given the id of an owner node in the AST, returns the corresponding `OwnerId`.
     fn owner_id(&self, node: NodeId) -> hir::OwnerId {
         hir::OwnerId { def_id: self.local_def_id(node) }
@@ -594,6 +705,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let current_impl_trait_defs = std::mem::take(&mut self.impl_trait_defs);
         let current_impl_trait_bounds = std::mem::take(&mut self.impl_trait_bounds);
         let current_delayed_lints = std::mem::take(&mut self.delayed_lints);
+        let current_children = std::mem::take(&mut self.children);
 
         // Do not reset `next_node_id` and `node_id_to_def_id`:
         // we want `f` to be able to refer to the `LocalDefId`s that the caller created.
@@ -628,9 +740,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         self.impl_trait_defs = current_impl_trait_defs;
         self.impl_trait_bounds = current_impl_trait_bounds;
         self.delayed_lints = current_delayed_lints;
+        self.children = current_children;
+        self.children.extend_unord(info.children.items().map(|(&def_id, &info)| (def_id, info)));
 
-        debug_assert!(!self.children.iter().any(|(id, _)| id == &owner_id.def_id));
-        self.children.push((owner_id.def_id, hir::MaybeOwner::Owner(info)));
+        debug_assert!(!self.children.contains_key(&owner_id.def_id));
+        self.children.insert(owner_id.def_id, hir::MaybeOwner::Owner(info));
     }
 
     fn make_owner_info(&mut self, node: hir::OwnerNode<'hir>) -> &'hir hir::OwnerInfo<'hir> {
@@ -639,6 +753,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let define_opaque = std::mem::take(&mut self.define_opaque);
         let trait_map = std::mem::take(&mut self.trait_map);
         let delayed_lints = std::mem::take(&mut self.delayed_lints).into_boxed_slice();
+        let children = std::mem::take(&mut self.children);
 
         #[cfg(debug_assertions)]
         for (id, attrs) in attrs.iter() {
@@ -652,16 +767,39 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let bodies = SortedMap::from_presorted_elements(bodies);
 
         // Don't hash unless necessary, because it's expensive.
-        let (opt_hash_including_bodies, attrs_hash, delayed_lints_hash) =
+        let (bodies_hash, attrs_hash, delayed_lints_hash) =
             self.tcx.hash_owner_nodes(node, &bodies, &attrs, &delayed_lints, define_opaque);
         let num_nodes = self.item_local_id_counter.as_usize();
         let (nodes, parenting) = index::index_hir(self.tcx, node, &bodies, num_nodes);
-        let nodes = hir::OwnerNodes { opt_hash_including_bodies, nodes, bodies };
+        let nodes = hir::OwnerNodes { opt_hash: bodies_hash, nodes, bodies };
         let attrs = hir::AttributeMap { map: attrs, opt_hash: attrs_hash, define_opaque };
         let delayed_lints =
             hir::lints::DelayedLints { lints: delayed_lints, opt_hash: delayed_lints_hash };
 
-        self.arena.alloc(hir::OwnerInfo { nodes, parenting, attrs, trait_map, delayed_lints })
+        let opt_hash = if self.tcx.needs_crate_hash() {
+            Some(self.tcx.with_stable_hashing_context(|mut hcx| {
+                let mut stable_hasher = StableHasher::new();
+                nodes.hash_stable(&mut hcx, &mut stable_hasher);
+                parenting.hash_stable(&mut hcx, &mut stable_hasher);
+                attrs.hash_stable(&mut hcx, &mut stable_hasher);
+                trait_map.hash_stable(&mut hcx, &mut stable_hasher);
+                delayed_lints.hash_stable(&mut hcx, &mut stable_hasher);
+                children.hash_stable(&mut hcx, &mut stable_hasher);
+                stable_hasher.finish()
+            }))
+        } else {
+            None
+        };
+
+        self.arena.alloc(hir::OwnerInfo {
+            opt_hash,
+            nodes,
+            parenting,
+            attrs,
+            trait_map,
+            delayed_lints,
+            children,
+        })
     }
 
     /// This method allocates a new `HirId` for the given `NodeId`.
@@ -680,11 +818,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let hir_id = HirId { owner, local_id };
 
         if let Some(def_id) = self.opt_local_def_id(ast_node_id) {
-            self.children.push((def_id, hir::MaybeOwner::NonOwner(hir_id)));
+            self.children.insert(def_id, hir::MaybeOwner::NonOwner(hir_id));
         }
 
-        if let Some(traits) = self.resolver.trait_map.remove(&ast_node_id) {
-            self.trait_map.insert(hir_id.local_id, traits.into_boxed_slice());
+        if let Some(traits) = self.resolver.trait_map.get(&ast_node_id) {
+            self.trait_map.insert(hir_id.local_id, &traits[..]);
         }
 
         // Check whether the same `NodeId` is lowered more than once.
@@ -725,7 +863,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     }
 
     fn expect_full_res(&mut self, id: NodeId) -> Res<NodeId> {
-        self.resolver.get_partial_res(id).map_or(Res::Err, |pr| pr.expect_full_res())
+        self.get_partial_res(id).map_or(Res::Err, |pr| pr.expect_full_res())
     }
 
     fn lower_import_res(&mut self, id: NodeId, span: Span) -> PerNS<Option<Res>> {
@@ -820,6 +958,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     param,
                     Some(kw::UnderscoreLifetime),
                     DefKind::LifetimeParam,
+                    DefPathData::DesugaredAnonymousLifetime,
                     ident.span,
                 );
                 debug!(?_def_id);
@@ -863,7 +1002,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             .collect();
         let extra_lifetimes = self.resolver.extra_lifetime_params(binder);
         debug!(?extra_lifetimes);
-        generic_params.extend(extra_lifetimes.into_iter().filter_map(|(ident, node_id, res)| {
+        generic_params.extend(extra_lifetimes.iter().filter_map(|&(ident, node_id, res)| {
             self.lifetime_res_to_generic_param(ident, node_id, res, hir::GenericParamSource::Binder)
         }));
         let generic_params = self.arena.alloc_from_iter(generic_params);
@@ -1152,7 +1291,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     // FIXME: Should we be handling `(PATH_TO_CONST)`?
                     TyKind::Path(None, path) => {
                         if let Some(res) = self
-                            .resolver
                             .get_partial_res(ty.id)
                             .and_then(|partial_res| partial_res.full_res())
                         {
@@ -1199,7 +1337,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         // The other cases when a qpath should be opportunistically made a trait object are handled
         // by `ty_path`.
         if qself.is_none()
-            && let Some(partial_res) = self.resolver.get_partial_res(t.id)
+            && let Some(partial_res) = self.get_partial_res(t.id)
             && let Some(Res::Def(DefKind::Trait | DefKind::TraitAlias, _)) = partial_res.full_res()
         {
             let (bounds, lifetime_bound) = self.with_dyn_type_scope(true, |this| {
@@ -1540,7 +1678,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 let [segment] = path.segments.as_slice() else {
                     panic!();
                 };
-                let res = self.resolver.get_partial_res(*id).map_or(Res::Err, |partial_res| {
+                let res = self.get_partial_res(*id).map_or(Res::Err, |partial_res| {
                     partial_res.full_res().expect("no partial res expected for precise capture arg")
                 });
                 hir::PreciseCapturingArg::Param(hir::PreciseCapturingNonLifetimeArg {
@@ -2155,7 +2293,13 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             // We're lowering a const argument that was originally thought to be a type argument,
             // so the def collector didn't create the def ahead of time. That's why we have to do
             // it here.
-            let def_id = self.create_def(node_id, None, DefKind::AnonConst, span);
+            let def_id = self.create_def(
+                node_id,
+                None,
+                DefKind::AnonConst,
+                DefPathData::LateAnonConst,
+                span,
+            );
             let hir_id = self.lower_node_id(node_id);
 
             let path_expr = Expr {
@@ -2201,7 +2345,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             &anon.value
         };
         let maybe_res =
-            self.resolver.get_partial_res(expr.id).and_then(|partial_res| partial_res.full_res());
+            self.get_partial_res(expr.id).and_then(|partial_res| partial_res.full_res());
         if let ExprKind::Path(qself, path) = &expr.kind
             && path.is_potential_trivial_const_arg(tcx.features().min_generic_const_args())
             && (tcx.features().min_generic_const_args()
@@ -2495,7 +2639,7 @@ impl<'hir> GenericArgsCtor<'hir> {
             && self.parenthesized == hir::GenericArgsParentheses::No
     }
 
-    fn into_generic_args(self, this: &LoweringContext<'_, 'hir>) -> &'hir hir::GenericArgs<'hir> {
+    fn into_generic_args(self, this: &LoweringContext<'hir>) -> &'hir hir::GenericArgs<'hir> {
         let ga = hir::GenericArgs {
             args: this.arena.alloc_from_iter(self.args),
             constraints: self.constraints,
diff --git a/compiler/rustc_ast_lowering/src/pat.rs b/compiler/rustc_ast_lowering/src/pat.rs
index e444062104813..7b0ab6df232e7 100644
--- a/compiler/rustc_ast_lowering/src/pat.rs
+++ b/compiler/rustc_ast_lowering/src/pat.rs
@@ -4,6 +4,7 @@ use rustc_ast::ptr::P;
 use rustc_ast::*;
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_hir::def::{DefKind, Res};
+use rustc_hir::definitions::DefPathData;
 use rustc_hir::{self as hir, LangItem};
 use rustc_middle::span_bug;
 use rustc_span::source_map::{Spanned, respan};
@@ -12,10 +13,11 @@ use rustc_span::{DesugaringKind, Ident, Span};
 use super::errors::{
     ArbitraryExpressionInPattern, ExtraDoubleDot, MisplacedDoubleDot, SubTupleBinding,
 };
-use super::{ImplTraitContext, LoweringContext, ParamMode, ResolverAstLoweringExt};
-use crate::{AllowReturnTypeNotation, ImplTraitPosition};
+use super::{
+    AllowReturnTypeNotation, ImplTraitContext, ImplTraitPosition, LoweringContext, ParamMode,
+};
 
-impl<'a, 'hir> LoweringContext<'a, 'hir> {
+impl<'hir> LoweringContext<'hir> {
     pub(crate) fn lower_pat(&mut self, pattern: &Pat) -> &'hir hir::Pat<'hir> {
         self.arena.alloc(self.lower_pat_mut(pattern))
     }
@@ -283,7 +285,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         hir_id: hir::HirId,
         lower_sub: impl FnOnce(&mut Self) -> Option<&'hir hir::Pat<'hir>>,
     ) -> hir::PatKind<'hir> {
-        match self.resolver.get_partial_res(p.id).map(|d| d.expect_full_res()) {
+        match self.get_partial_res(p.id).map(|d| d.expect_full_res()) {
             // `None` can occur in body-less function signatures
             res @ (None | Some(Res::Local(_))) => {
                 let binding_id = match res {
@@ -524,7 +526,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         // We're generating a range end that didn't exist in the AST,
         // so the def collector didn't create the def ahead of time. That's why we have to do
         // it here.
-        let def_id = self.create_def(node_id, None, DefKind::AnonConst, span);
+        let def_id =
+            self.create_def(node_id, None, DefKind::AnonConst, DefPathData::LateAnonConst, span);
         let hir_id = self.lower_node_id(node_id);
 
         let unstable_span = self.mark_span_with_reason(
diff --git a/compiler/rustc_ast_lowering/src/path.rs b/compiler/rustc_ast_lowering/src/path.rs
index c80ef275c801a..0969a82784a1f 100644
--- a/compiler/rustc_ast_lowering/src/path.rs
+++ b/compiler/rustc_ast_lowering/src/path.rs
@@ -19,7 +19,7 @@ use super::{
     LifetimeRes, LoweringContext, ParamMode, ResolverAstLoweringExt,
 };
 
-impl<'a, 'hir> LoweringContext<'a, 'hir> {
+impl<'hir> LoweringContext<'hir> {
     #[instrument(level = "trace", skip(self))]
     pub(crate) fn lower_qpath(
         &mut self,
@@ -38,8 +38,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             // Reject cases like `<impl Trait>::Assoc` and `<impl Trait as Trait>::Assoc`.
             .map(|q| self.lower_ty(&q.ty, ImplTraitContext::Disallowed(ImplTraitPosition::Path)));
 
-        let partial_res =
-            self.resolver.get_partial_res(id).unwrap_or_else(|| PartialRes::new(Res::Err));
+        let partial_res = self.get_partial_res(id).unwrap_or_else(|| PartialRes::new(Res::Err));
         let base_res = partial_res.base_res();
         let unresolved_segments = partial_res.unresolved_segments();
 
diff --git a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
index 7c69baba62e8b..a06540f832507 100644
--- a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
@@ -681,46 +681,30 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
             return (false, false, None);
         }
         let my_def = self.body.source.def_id();
-        let my_hir = self.infcx.tcx.local_def_id_to_hir_id(my_def.as_local().unwrap());
         let Some(td) =
             self.infcx.tcx.impl_of_method(my_def).and_then(|x| self.infcx.tcx.trait_id_of_impl(x))
         else {
             return (false, false, None);
         };
+
+        let implemented_trait_item = self.infcx.tcx.associated_item(my_def).trait_item_def_id;
+
         (
             true,
             td.is_local(),
-            td.as_local().and_then(|tld| match self.infcx.tcx.hir_node_by_def_id(tld) {
-                Node::Item(hir::Item {
-                    kind: hir::ItemKind::Trait(_, _, _, _, _, items), ..
-                }) => {
-                    let mut f_in_trait_opt = None;
-                    for hir::TraitItemRef { id: fi, kind: k, .. } in *items {
-                        let hi = fi.hir_id();
-                        if !matches!(k, hir::AssocItemKind::Fn { .. }) {
-                            continue;
-                        }
-                        if self.infcx.tcx.hir_name(hi) != self.infcx.tcx.hir_name(my_hir) {
-                            continue;
-                        }
-                        f_in_trait_opt = Some(hi);
-                        break;
-                    }
-                    f_in_trait_opt.and_then(|f_in_trait| {
-                        if let Node::TraitItem(ti) = self.infcx.tcx.hir_node(f_in_trait)
-                            && let hir::TraitItemKind::Fn(sig, _) = ti.kind
-                            && let Some(ty) = sig.decl.inputs.get(local.index() - 1)
-                            && let hir::TyKind::Ref(_, mut_ty) = ty.kind
-                            && let hir::Mutability::Not = mut_ty.mutbl
-                            && sig.decl.implicit_self.has_implicit_self()
-                        {
-                            Some(ty.span)
-                        } else {
-                            None
-                        }
-                    })
+            implemented_trait_item.and_then(|f_in_trait| {
+                let f_in_trait = f_in_trait.as_local()?;
+                if let Node::TraitItem(ti) = self.infcx.tcx.hir_node_by_def_id(f_in_trait)
+                    && let hir::TraitItemKind::Fn(sig, _) = ti.kind
+                    && let Some(ty) = sig.decl.inputs.get(local.index() - 1)
+                    && let hir::TyKind::Ref(_, mut_ty) = ty.kind
+                    && let hir::Mutability::Not = mut_ty.mutbl
+                    && sig.decl.implicit_self.has_implicit_self()
+                {
+                    Some(ty.span)
+                } else {
+                    None
                 }
-                _ => None,
             }),
         )
     }
diff --git a/compiler/rustc_driver_impl/src/pretty.rs b/compiler/rustc_driver_impl/src/pretty.rs
index 688307a941f30..478b15f516a49 100644
--- a/compiler/rustc_driver_impl/src/pretty.rs
+++ b/compiler/rustc_driver_impl/src/pretty.rs
@@ -211,7 +211,7 @@ impl<'tcx> PrintExtra<'tcx> {
     {
         match self {
             PrintExtra::AfterParsing { krate, .. } => f(krate),
-            PrintExtra::NeedsAstMap { tcx } => f(&tcx.resolver_for_lowering().borrow().1),
+            PrintExtra::NeedsAstMap { tcx } => f(&tcx.resolver_for_lowering().1.borrow()),
         }
     }
 
@@ -261,7 +261,7 @@ pub fn print<'tcx>(sess: &Session, ppm: PpMode, ex: PrintExtra<'tcx>) {
         }
         AstTreeExpanded => {
             debug!("pretty-printing expanded AST");
-            format!("{:#?}", ex.tcx().resolver_for_lowering().borrow().1)
+            format!("{:#?}", ex.tcx().resolver_for_lowering().1.borrow())
         }
         Hir(s) => {
             debug!("pretty printing HIR {:?}", s);
diff --git a/compiler/rustc_hir/src/definitions.rs b/compiler/rustc_hir/src/definitions.rs
index f93b9e5af5345..5127f613cc497 100644
--- a/compiler/rustc_hir/src/definitions.rs
+++ b/compiler/rustc_hir/src/definitions.rs
@@ -306,6 +306,10 @@ pub enum DefPathData {
     Ctor,
     /// A constant expression (see `{ast,hir}::AnonConst`).
     AnonConst,
+    /// A constant expression created during AST->HIR lowering..
+    LateAnonConst,
+    /// A fresh anonymous lifetime created by desugaring elided lifetimes.
+    DesugaredAnonymousLifetime,
     /// An existential `impl Trait` type node.
     /// Argument position `impl Trait` have a `TypeNs` with their pretty-printed name.
     OpaqueTy,
@@ -450,6 +454,8 @@ impl DefPathData {
             TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name)
             | OpaqueLifetime(name) => Some(name),
 
+            DesugaredAnonymousLifetime => Some(kw::UnderscoreLifetime),
+
             Impl
             | ForeignMod
             | CrateRoot
@@ -458,6 +464,7 @@ impl DefPathData {
             | Closure
             | Ctor
             | AnonConst
+            | LateAnonConst
             | OpaqueTy
             | AnonAssocTy(..)
             | SyntheticCoroutineBody
@@ -471,6 +478,8 @@ impl DefPathData {
             TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) | AnonAssocTy(name)
             | OpaqueLifetime(name) => Some(name),
 
+            DesugaredAnonymousLifetime => Some(kw::UnderscoreLifetime),
+
             Impl
             | ForeignMod
             | CrateRoot
@@ -479,6 +488,7 @@ impl DefPathData {
             | Closure
             | Ctor
             | AnonConst
+            | LateAnonConst
             | OpaqueTy
             | SyntheticCoroutineBody
             | NestedStatic => None,
@@ -498,7 +508,8 @@ impl DefPathData {
             GlobalAsm => DefPathDataName::Anon { namespace: sym::global_asm },
             Closure => DefPathDataName::Anon { namespace: sym::closure },
             Ctor => DefPathDataName::Anon { namespace: sym::constructor },
-            AnonConst => DefPathDataName::Anon { namespace: sym::constant },
+            AnonConst | LateAnonConst => DefPathDataName::Anon { namespace: sym::constant },
+            DesugaredAnonymousLifetime => DefPathDataName::Named(kw::UnderscoreLifetime),
             OpaqueTy => DefPathDataName::Anon { namespace: sym::opaque },
             AnonAssocTy(..) => DefPathDataName::Anon { namespace: sym::anon_assoc },
             SyntheticCoroutineBody => DefPathDataName::Anon { namespace: sym::synthetic },
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index ca6405ea20944..1aafe58509e2a 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -18,6 +18,7 @@ use rustc_attr_data_structures::AttributeKind;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::sorted_map::SortedMap;
 use rustc_data_structures::tagged_ptr::TaggedRef;
+use rustc_data_structures::unord::UnordMap;
 use rustc_index::IndexVec;
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_span::def_id::LocalDefId;
@@ -1474,7 +1475,7 @@ impl<'tcx> AttributeMap<'tcx> {
 pub struct OwnerNodes<'tcx> {
     /// Pre-computed hash of the full HIR. Used in the crate hash. Only present
     /// when incr. comp. is enabled.
-    pub opt_hash_including_bodies: Option<Fingerprint>,
+    pub opt_hash: Option<Fingerprint>,
     /// Full HIR for the current owner.
     // The zeroth node's parent should never be accessed: the owner's parent is computed by the
     // hir_owner_parent query. It is set to `ItemLocalId::INVALID` to force an ICE if accidentally
@@ -1507,13 +1508,13 @@ impl fmt::Debug for OwnerNodes<'_> {
                 }),
             )
             .field("bodies", &self.bodies)
-            .field("opt_hash_including_bodies", &self.opt_hash_including_bodies)
+            .field("opt_hash", &self.opt_hash)
             .finish()
     }
 }
 
 /// Full information resulting from lowering an AST node.
-#[derive(Debug, HashStable_Generic)]
+#[derive(Debug)]
 pub struct OwnerInfo<'hir> {
     /// Contents of the HIR.
     pub nodes: OwnerNodes<'hir>,
@@ -1523,11 +1524,14 @@ pub struct OwnerInfo<'hir> {
     pub attrs: AttributeMap<'hir>,
     /// Map indicating what traits are in scope for places where this
     /// is relevant; generated by resolve.
-    pub trait_map: ItemLocalMap<Box<[TraitCandidate]>>,
-
+    pub trait_map: ItemLocalMap<&'hir [TraitCandidate]>,
     /// Lints delayed during ast lowering to be emitted
     /// after hir has completely built
     pub delayed_lints: DelayedLints,
+    /// Owners generated as side-effect by lowering.
+    pub children: UnordMap<LocalDefId, MaybeOwner<'hir>>,
+    // Only present when the crate hash is needed.
+    pub opt_hash: Option<Fingerprint>,
 }
 
 impl<'tcx> OwnerInfo<'tcx> {
@@ -1541,36 +1545,23 @@ impl<'tcx> OwnerInfo<'tcx> {
 pub enum MaybeOwner<'tcx> {
     Owner(&'tcx OwnerInfo<'tcx>),
     NonOwner(HirId),
-    /// Used as a placeholder for unused LocalDefId.
-    Phantom,
 }
 
 impl<'tcx> MaybeOwner<'tcx> {
+    #[inline]
     pub fn as_owner(self) -> Option<&'tcx OwnerInfo<'tcx>> {
         match self {
             MaybeOwner::Owner(i) => Some(i),
-            MaybeOwner::NonOwner(_) | MaybeOwner::Phantom => None,
+            MaybeOwner::NonOwner(_) => None,
         }
     }
 
+    #[inline]
     pub fn unwrap(self) -> &'tcx OwnerInfo<'tcx> {
         self.as_owner().unwrap_or_else(|| panic!("Not a HIR owner"))
     }
 }
 
-/// The top-level data structure that stores the entire contents of
-/// the crate currently being compiled.
-///
-/// For more details, see the [rustc dev guide].
-///
-/// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/hir.html
-#[derive(Debug)]
-pub struct Crate<'hir> {
-    pub owners: IndexVec<LocalDefId, MaybeOwner<'hir>>,
-    // Only present when incr. comp. is enabled.
-    pub opt_hir_hash: Option<Fingerprint>,
-}
-
 #[derive(Debug, Clone, Copy, HashStable_Generic)]
 pub struct Closure<'hir> {
     pub def_id: LocalDefId,
@@ -3171,6 +3162,8 @@ pub struct ImplItem<'hir> {
     pub span: Span,
     pub vis_span: Span,
     pub has_delayed_lints: bool,
+    /// When we are in a trait impl, link to the trait-item's id.
+    pub trait_item_def_id: Option<DefId>,
 }
 
 impl<'hir> ImplItem<'hir> {
@@ -4135,7 +4128,7 @@ impl<'hir> Item<'hir> {
 
         expect_mod, (Ident, &'hir Mod<'hir>), ItemKind::Mod(ident, m), (*ident, m);
 
-        expect_foreign_mod, (ExternAbi, &'hir [ForeignItemRef]),
+        expect_foreign_mod, (ExternAbi, &'hir [ForeignItemId]),
             ItemKind::ForeignMod { abi, items }, (*abi, items);
 
         expect_global_asm, &'hir InlineAsm<'hir>, ItemKind::GlobalAsm { asm, .. }, asm;
@@ -4159,7 +4152,7 @@ impl<'hir> Item<'hir> {
                 Ident,
                 &'hir Generics<'hir>,
                 GenericBounds<'hir>,
-                &'hir [TraitItemRef]
+                &'hir [TraitItemId]
             ),
             ItemKind::Trait(is_auto, safety, ident, generics, bounds, items),
             (*is_auto, *safety, *ident, generics, bounds, items);
@@ -4312,7 +4305,7 @@ pub enum ItemKind<'hir> {
     /// A module.
     Mod(Ident, &'hir Mod<'hir>),
     /// An external module, e.g. `extern { .. }`.
-    ForeignMod { abi: ExternAbi, items: &'hir [ForeignItemRef] },
+    ForeignMod { abi: ExternAbi, items: &'hir [ForeignItemId] },
     /// Module-level inline assembly (from `global_asm!`).
     GlobalAsm {
         asm: &'hir InlineAsm<'hir>,
@@ -4332,7 +4325,7 @@ pub enum ItemKind<'hir> {
     /// A union definition, e.g., `union Foo<A, B> {x: A, y: B}`.
     Union(Ident, &'hir Generics<'hir>, VariantData<'hir>),
     /// A trait definition.
-    Trait(IsAuto, Safety, Ident, &'hir Generics<'hir>, GenericBounds<'hir>, &'hir [TraitItemRef]),
+    Trait(IsAuto, Safety, Ident, &'hir Generics<'hir>, GenericBounds<'hir>, &'hir [TraitItemId]),
     /// A trait alias.
     TraitAlias(Ident, &'hir Generics<'hir>, GenericBounds<'hir>),
 
@@ -4359,7 +4352,7 @@ pub struct Impl<'hir> {
     pub of_trait: Option<TraitRef<'hir>>,
 
     pub self_ty: &'hir Ty<'hir>,
-    pub items: &'hir [ImplItemRef],
+    pub items: &'hir [ImplItemId],
 }
 
 impl ItemKind<'_> {
@@ -4402,43 +4395,6 @@ impl ItemKind<'_> {
     }
 }
 
-/// A reference from an trait to one of its associated items. This
-/// contains the item's id, naturally, but also the item's name and
-/// some other high-level details (like whether it is an associated
-/// type or method, and whether it is public). This allows other
-/// passes to find the impl they want without loading the ID (which
-/// means fewer edges in the incremental compilation graph).
-#[derive(Debug, Clone, Copy, HashStable_Generic)]
-pub struct TraitItemRef {
-    pub id: TraitItemId,
-    pub ident: Ident,
-    pub kind: AssocItemKind,
-    pub span: Span,
-}
-
-/// A reference from an impl to one of its associated items. This
-/// contains the item's ID, naturally, but also the item's name and
-/// some other high-level details (like whether it is an associated
-/// type or method, and whether it is public). This allows other
-/// passes to find the impl they want without loading the ID (which
-/// means fewer edges in the incremental compilation graph).
-#[derive(Debug, Clone, Copy, HashStable_Generic)]
-pub struct ImplItemRef {
-    pub id: ImplItemId,
-    pub ident: Ident,
-    pub kind: AssocItemKind,
-    pub span: Span,
-    /// When we are in a trait impl, link to the trait-item's id.
-    pub trait_item_def_id: Option<DefId>,
-}
-
-#[derive(Copy, Clone, PartialEq, Debug, HashStable_Generic)]
-pub enum AssocItemKind {
-    Const,
-    Fn { has_self: bool },
-    Type,
-}
-
 // The bodies for items are stored "out of line", in a separate
 // hashmap in the `Crate`. Here we just record the hir-id of the item
 // so it can fetched later.
@@ -4455,19 +4411,6 @@ impl ForeignItemId {
     }
 }
 
-/// A reference from a foreign block to one of its items. This
-/// contains the item's ID, naturally, but also the item's name and
-/// some other high-level details (like whether it is an associated
-/// type or method, and whether it is public). This allows other
-/// passes to find the impl they want without loading the ID (which
-/// means fewer edges in the incremental compilation graph).
-#[derive(Debug, Clone, Copy, HashStable_Generic)]
-pub struct ForeignItemRef {
-    pub id: ForeignItemId,
-    pub ident: Ident,
-    pub span: Span,
-}
-
 #[derive(Debug, Clone, Copy, HashStable_Generic)]
 pub struct ForeignItem<'hir> {
     pub ident: Ident,
@@ -4968,7 +4911,7 @@ mod size_asserts {
     static_assert_size!(GenericBound<'_>, 64);
     static_assert_size!(Generics<'_>, 56);
     static_assert_size!(Impl<'_>, 80);
-    static_assert_size!(ImplItem<'_>, 88);
+    static_assert_size!(ImplItem<'_>, 96);
     static_assert_size!(ImplItemKind<'_>, 40);
     static_assert_size!(Item<'_>, 88);
     static_assert_size!(ItemKind<'_>, 64);
diff --git a/compiler/rustc_hir/src/intravisit.rs b/compiler/rustc_hir/src/intravisit.rs
index a0bc318e2ca66..b79519f29186b 100644
--- a/compiler/rustc_hir/src/intravisit.rs
+++ b/compiler/rustc_hir/src/intravisit.rs
@@ -435,17 +435,17 @@ pub trait Visitor<'v>: Sized {
     fn visit_trait_item(&mut self, ti: &'v TraitItem<'v>) -> Self::Result {
         walk_trait_item(self, ti)
     }
-    fn visit_trait_item_ref(&mut self, ii: &'v TraitItemRef) -> Self::Result {
-        walk_trait_item_ref(self, ii)
+    fn visit_trait_item_ref(&mut self, ii: &'v TraitItemId) -> Self::Result {
+        walk_trait_item_ref(self, *ii)
     }
     fn visit_impl_item(&mut self, ii: &'v ImplItem<'v>) -> Self::Result {
         walk_impl_item(self, ii)
     }
-    fn visit_foreign_item_ref(&mut self, ii: &'v ForeignItemRef) -> Self::Result {
-        walk_foreign_item_ref(self, ii)
+    fn visit_foreign_item_ref(&mut self, ii: &'v ForeignItemId) -> Self::Result {
+        walk_foreign_item_ref(self, *ii)
     }
-    fn visit_impl_item_ref(&mut self, ii: &'v ImplItemRef) -> Self::Result {
-        walk_impl_item_ref(self, ii)
+    fn visit_impl_item_ref(&mut self, ii: &'v ImplItemId) -> Self::Result {
+        walk_impl_item_ref(self, *ii)
     }
     fn visit_trait_ref(&mut self, t: &'v TraitRef<'v>) -> Self::Result {
         walk_trait_ref(self, t)
@@ -499,9 +499,6 @@ pub trait Visitor<'v>: Sized {
     fn visit_attribute(&mut self, _attr: &'v Attribute) -> Self::Result {
         Self::Result::output()
     }
-    fn visit_associated_item_kind(&mut self, kind: &'v AssocItemKind) -> Self::Result {
-        walk_associated_item_kind(self, kind)
-    }
     fn visit_defaultness(&mut self, defaultness: &'v Defaultness) -> Self::Result {
         walk_defaultness(self, defaultness)
     }
@@ -1248,14 +1245,8 @@ pub fn walk_trait_item<'v, V: Visitor<'v>>(
     V::Result::output()
 }
 
-pub fn walk_trait_item_ref<'v, V: Visitor<'v>>(
-    visitor: &mut V,
-    trait_item_ref: &'v TraitItemRef,
-) -> V::Result {
-    let TraitItemRef { id, ident, ref kind, span: _ } = *trait_item_ref;
-    try_visit!(visitor.visit_nested_trait_item(id));
-    try_visit!(visitor.visit_ident(ident));
-    visitor.visit_associated_item_kind(kind)
+pub fn walk_trait_item_ref<'v, V: Visitor<'v>>(visitor: &mut V, id: TraitItemId) -> V::Result {
+    visitor.visit_nested_trait_item(id)
 }
 
 pub fn walk_impl_item<'v, V: Visitor<'v>>(
@@ -1271,6 +1262,7 @@ pub fn walk_impl_item<'v, V: Visitor<'v>>(
         span: _,
         vis_span: _,
         has_delayed_lints: _,
+        trait_item_def_id: _,
     } = *impl_item;
 
     try_visit!(visitor.visit_ident(ident));
@@ -1293,23 +1285,12 @@ pub fn walk_impl_item<'v, V: Visitor<'v>>(
     }
 }
 
-pub fn walk_foreign_item_ref<'v, V: Visitor<'v>>(
-    visitor: &mut V,
-    foreign_item_ref: &'v ForeignItemRef,
-) -> V::Result {
-    let ForeignItemRef { id, ident, span: _ } = *foreign_item_ref;
-    try_visit!(visitor.visit_nested_foreign_item(id));
-    visitor.visit_ident(ident)
+pub fn walk_foreign_item_ref<'v, V: Visitor<'v>>(visitor: &mut V, id: ForeignItemId) -> V::Result {
+    visitor.visit_nested_foreign_item(id)
 }
 
-pub fn walk_impl_item_ref<'v, V: Visitor<'v>>(
-    visitor: &mut V,
-    impl_item_ref: &'v ImplItemRef,
-) -> V::Result {
-    let ImplItemRef { id, ident, ref kind, span: _, trait_item_def_id: _ } = *impl_item_ref;
-    try_visit!(visitor.visit_nested_impl_item(id));
-    try_visit!(visitor.visit_ident(ident));
-    visitor.visit_associated_item_kind(kind)
+pub fn walk_impl_item_ref<'v, V: Visitor<'v>>(visitor: &mut V, id: ImplItemId) -> V::Result {
+    visitor.visit_nested_impl_item(id)
 }
 
 pub fn walk_trait_ref<'v, V: Visitor<'v>>(
@@ -1483,13 +1464,6 @@ pub fn walk_assoc_item_constraint<'v, V: Visitor<'v>>(
     V::Result::output()
 }
 
-pub fn walk_associated_item_kind<'v, V: Visitor<'v>>(_: &mut V, _: &'v AssocItemKind) -> V::Result {
-    // No visitable content here: this fn exists so you can call it if
-    // the right thing to do, should content be added in the future,
-    // would be to walk it.
-    V::Result::output()
-}
-
 pub fn walk_defaultness<'v, V: Visitor<'v>>(_: &mut V, _: &'v Defaultness) -> V::Result {
     // No visitable content here: this fn exists so you can call it if
     // the right thing to do, should content be added in the future,
diff --git a/compiler/rustc_hir/src/stable_hash_impls.rs b/compiler/rustc_hir/src/stable_hash_impls.rs
index 6acf1524b608f..c20cb81d6ed2d 100644
--- a/compiler/rustc_hir/src/stable_hash_impls.rs
+++ b/compiler/rustc_hir/src/stable_hash_impls.rs
@@ -3,7 +3,7 @@ use rustc_span::def_id::DefPathHash;
 
 use crate::HashIgnoredAttrId;
 use crate::hir::{
-    AttributeMap, BodyId, Crate, ForeignItemId, ImplItemId, ItemId, OwnerNodes, TraitItemId,
+    AttributeMap, BodyId, ForeignItemId, ImplItemId, ItemId, OwnerInfo, OwnerNodes, TraitItemId,
 };
 use crate::hir_id::{HirId, ItemLocalId};
 use crate::lints::DelayedLints;
@@ -92,18 +92,17 @@ impl<HirCtx: crate::HashStableContext> ToStableHashKey<HirCtx> for ForeignItemId
 // in "DefPath Mode".
 
 impl<'tcx, HirCtx: crate::HashStableContext> HashStable<HirCtx> for OwnerNodes<'tcx> {
+    #[inline]
     fn hash_stable(&self, hcx: &mut HirCtx, hasher: &mut StableHasher) {
-        // We ignore the `nodes` and `bodies` fields since these refer to information included in
-        // `hash` which is hashed in the collector and used for the crate hash.
-        // `local_id_to_def_id` is also ignored because is dependent on the body, then just hashing
-        // the body satisfies the condition of two nodes being different have different
-        // `hash_stable` results.
-        let OwnerNodes { opt_hash_including_bodies, nodes: _, bodies: _ } = *self;
-        opt_hash_including_bodies.unwrap().hash_stable(hcx, hasher);
+        // We ignore the other fields since these refer to information included in
+        // `opt_hash` which is hashed in the collector and used for the crate hash.
+        let OwnerNodes { opt_hash, .. } = *self;
+        opt_hash.unwrap().hash_stable(hcx, hasher);
     }
 }
 
 impl<HirCtx: crate::HashStableContext> HashStable<HirCtx> for DelayedLints {
+    #[inline]
     fn hash_stable(&self, hcx: &mut HirCtx, hasher: &mut StableHasher) {
         let DelayedLints { opt_hash, .. } = *self;
         opt_hash.unwrap().hash_stable(hcx, hasher);
@@ -111,6 +110,7 @@ impl<HirCtx: crate::HashStableContext> HashStable<HirCtx> for DelayedLints {
 }
 
 impl<'tcx, HirCtx: crate::HashStableContext> HashStable<HirCtx> for AttributeMap<'tcx> {
+    #[inline]
     fn hash_stable(&self, hcx: &mut HirCtx, hasher: &mut StableHasher) {
         // We ignore the `map` since it refers to information included in `opt_hash` which is
         // hashed in the collector and used for the crate hash.
@@ -119,10 +119,13 @@ impl<'tcx, HirCtx: crate::HashStableContext> HashStable<HirCtx> for AttributeMap
     }
 }
 
-impl<HirCtx: crate::HashStableContext> HashStable<HirCtx> for Crate<'_> {
+impl<'tcx, HirCtx: crate::HashStableContext> HashStable<HirCtx> for OwnerInfo<'tcx> {
+    #[inline]
     fn hash_stable(&self, hcx: &mut HirCtx, hasher: &mut StableHasher) {
-        let Crate { owners: _, opt_hir_hash } = self;
-        opt_hir_hash.unwrap().hash_stable(hcx, hasher)
+        // We ignore the rest since it refers to information included in `opt_hash` which is
+        // hashed in the collector and used for the crate hash.
+        let OwnerInfo { opt_hash, .. } = *self;
+        opt_hash.unwrap().hash_stable(hcx, hasher);
     }
 }
 
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index f4fcb13b1a126..5f5d3e7cb6ef3 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -931,8 +931,8 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(),
 
             check_abi(tcx, it.hir_id(), it.span, abi);
 
-            for item in items {
-                let def_id = item.id.owner_id.def_id;
+            for &item in items {
+                let def_id = item.owner_id.def_id;
 
                 let generics = tcx.generics_of(def_id);
                 let own_counts = generics.own_counts();
@@ -944,13 +944,14 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(),
                         (0, _) => ("const", "consts", None),
                         _ => ("type or const", "types or consts", None),
                     };
+                    let span = tcx.def_span(def_id);
                     struct_span_code_err!(
                         tcx.dcx(),
-                        item.span,
+                        span,
                         E0044,
                         "foreign items may not have {kinds} parameters",
                     )
-                    .with_span_label(item.span, format!("can't have {kinds} parameters"))
+                    .with_span_label(span, format!("can't have {kinds} parameters"))
                     .with_help(
                         // FIXME: once we start storing spans for type arguments, turn this
                         // into a suggestion.
@@ -964,22 +965,23 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(),
                     .emit();
                 }
 
-                let item = tcx.hir_foreign_item(item.id);
-                tcx.ensure_ok().generics_of(item.owner_id);
-                tcx.ensure_ok().type_of(item.owner_id);
-                tcx.ensure_ok().predicates_of(item.owner_id);
+                tcx.ensure_ok().generics_of(def_id);
+                tcx.ensure_ok().type_of(def_id);
+                tcx.ensure_ok().predicates_of(def_id);
                 if tcx.is_conditionally_const(def_id) {
                     tcx.ensure_ok().explicit_implied_const_bounds(def_id);
                     tcx.ensure_ok().const_conditions(def_id);
                 }
-                match item.kind {
-                    hir::ForeignItemKind::Fn(sig, ..) => {
-                        tcx.ensure_ok().codegen_fn_attrs(item.owner_id);
-                        tcx.ensure_ok().fn_sig(item.owner_id);
+                match tcx.def_kind(def_id) {
+                    DefKind::Fn => {
+                        tcx.ensure_ok().codegen_fn_attrs(def_id);
+                        tcx.ensure_ok().fn_sig(def_id);
+                        let item = tcx.hir_foreign_item(item);
+                        let hir::ForeignItemKind::Fn(sig, ..) = item.kind else { bug!() };
                         require_c_abi_if_c_variadic(tcx, sig.decl, abi, item.span);
                     }
-                    hir::ForeignItemKind::Static(..) => {
-                        tcx.ensure_ok().codegen_fn_attrs(item.owner_id);
+                    DefKind::Static { .. } => {
+                        tcx.ensure_ok().codegen_fn_attrs(def_id);
                     }
                     _ => (),
                 }
diff --git a/compiler/rustc_hir_analysis/src/check/intrinsic.rs b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
index cebf7d1b5324e..396d606599bbf 100644
--- a/compiler/rustc_hir_analysis/src/check/intrinsic.rs
+++ b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
@@ -59,7 +59,7 @@ fn equate_intrinsic_type<'tcx>(
 
 /// Returns the unsafety of the given intrinsic.
 fn intrinsic_operation_unsafety(tcx: TyCtxt<'_>, intrinsic_id: LocalDefId) -> hir::Safety {
-    let is_in_list = match tcx.item_name(intrinsic_id.into()) {
+    let is_in_list = match tcx.item_name(intrinsic_id) {
         // When adding a new intrinsic to this list,
         // it's usually worth updating that intrinsic's documentation
         // to note that it's safe to call, since
@@ -143,7 +143,7 @@ fn intrinsic_operation_unsafety(tcx: TyCtxt<'_>, intrinsic_id: LocalDefId) -> hi
             tcx.def_span(intrinsic_id),
             DiagMessage::from(format!(
                 "intrinsic safety mismatch between list of intrinsics within the compiler and core library intrinsics for intrinsic `{}`",
-                tcx.item_name(intrinsic_id.into())
+                tcx.item_name(intrinsic_id)
             )
         )).emit();
     }
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index 25064c327d051..d36f1761e4902 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -844,11 +844,9 @@ fn adt_def(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::AdtDef<'_> {
 fn trait_def(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::TraitDef {
     let item = tcx.hir_expect_item(def_id);
 
-    let (is_alias, is_auto, safety, items) = match item.kind {
-        hir::ItemKind::Trait(is_auto, safety, .., items) => {
-            (false, is_auto == hir::IsAuto::Yes, safety, items)
-        }
-        hir::ItemKind::TraitAlias(..) => (true, false, hir::Safety::Safe, &[][..]),
+    let (is_alias, is_auto, safety) = match item.kind {
+        hir::ItemKind::Trait(is_auto, safety, ..) => (false, is_auto == hir::IsAuto::Yes, safety),
+        hir::ItemKind::TraitAlias(..) => (true, false, hir::Safety::Safe),
         _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
     };
 
@@ -909,13 +907,16 @@ fn trait_def(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::TraitDef {
         // functions in the trait with default implementations
         .and_then(|(list, attr_span)| {
             let errors = list.iter().filter_map(|ident| {
-                let item = items.iter().find(|item| item.ident == *ident);
+                let item = tcx
+                    .associated_items(def_id)
+                    .filter_by_name_unhygienic(ident.name)
+                    .find(|item| item.ident(tcx) == *ident);
 
                 match item {
-                    Some(item) if matches!(item.kind, hir::AssocItemKind::Fn { .. }) => {
-                        if !tcx.defaultness(item.id.owner_id).has_value() {
+                    Some(item) if matches!(item.kind, ty::AssocKind::Fn { .. }) => {
+                        if !item.defaultness(tcx).has_value() {
                             tcx.dcx().emit_err(errors::FunctionNotHaveDefaultImplementation {
-                                span: item.span,
+                                span: tcx.def_span(item.def_id),
                                 note_span: attr_span,
                             });
 
@@ -926,7 +927,7 @@ fn trait_def(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::TraitDef {
                     }
                     Some(item) => {
                         tcx.dcx().emit_err(errors::MustImplementNotFunction {
-                            span: item.span,
+                            span: tcx.def_span(item.def_id),
                             span_note: errors::MustImplementNotFunctionSpanNote { span: attr_span },
                             note: errors::MustImplementNotFunctionNote {},
                         });
diff --git a/compiler/rustc_hir_pretty/src/lib.rs b/compiler/rustc_hir_pretty/src/lib.rs
index c523a03e012e4..a6d892115481e 100644
--- a/compiler/rustc_hir_pretty/src/lib.rs
+++ b/compiler/rustc_hir_pretty/src/lib.rs
@@ -654,8 +654,8 @@ impl<'a> State<'a> {
                 let (cb, ib) = self.head("extern");
                 self.word_nbsp(abi.to_string());
                 self.bopen(ib);
-                for item in items {
-                    self.ann.nested(self, Nested::ForeignItem(item.id));
+                for &foreign_item in items {
+                    self.ann.nested(self, Nested::ForeignItem(foreign_item));
                 }
                 self.bclose(item.span, cb);
             }
@@ -730,8 +730,8 @@ impl<'a> State<'a> {
 
                 self.space();
                 self.bopen(ib);
-                for impl_item in items {
-                    self.ann.nested(self, Nested::ImplItem(impl_item.id));
+                for &impl_item in items {
+                    self.ann.nested(self, Nested::ImplItem(impl_item));
                 }
                 self.bclose(item.span, cb);
             }
@@ -746,8 +746,8 @@ impl<'a> State<'a> {
                 self.print_where_clause(generics);
                 self.word(" ");
                 self.bopen(ib);
-                for trait_item in trait_items {
-                    self.ann.nested(self, Nested::TraitItem(trait_item.id));
+                for &trait_item in trait_items {
+                    self.ann.nested(self, Nested::TraitItem(trait_item));
                 }
                 self.bclose(item.span, cb);
             }
diff --git a/compiler/rustc_interface/src/passes.rs b/compiler/rustc_interface/src/passes.rs
index a438cde018c63..4308b87da0b1b 100644
--- a/compiler/rustc_interface/src/passes.rs
+++ b/compiler/rustc_interface/src/passes.rs
@@ -387,7 +387,8 @@ fn print_macro_stats(ecx: &ExtCtxt<'_>) {
 
 fn early_lint_checks(tcx: TyCtxt<'_>, (): ()) {
     let sess = tcx.sess;
-    let (resolver, krate) = &*tcx.resolver_for_lowering().borrow();
+    let (resolver, krate) = tcx.resolver_for_lowering();
+    let krate = &*krate.borrow();
     let mut lint_buffer = resolver.lint_buffer.steal();
 
     if sess.opts.unstable_opts.input_stats {
@@ -463,7 +464,7 @@ fn early_lint_checks(tcx: TyCtxt<'_>, (): ()) {
         tcx.registered_tools(()),
         Some(lint_buffer),
         rustc_lint::BuiltinCombinedEarlyLintPass::new(),
-        (&**krate, &*krate.attrs),
+        (&*krate, &*krate.attrs),
     )
 }
 
@@ -773,7 +774,7 @@ fn write_out_deps(tcx: TyCtxt<'_>, outputs: &OutputFilenames, out_filenames: &[P
 fn resolver_for_lowering_raw<'tcx>(
     tcx: TyCtxt<'tcx>,
     (): (),
-) -> (&'tcx Steal<(ty::ResolverAstLowering, Arc<ast::Crate>)>, &'tcx ty::ResolverGlobalCtxt) {
+) -> (&'tcx (ty::ResolverAstLowering, Steal<ast::Crate>), &'tcx ty::ResolverGlobalCtxt) {
     let arenas = Resolver::arenas();
     let _ = tcx.registered_tools(()); // Uses `crate_for_resolver`.
     let (krate, pre_configured_attrs) = tcx.crate_for_resolver(()).steal();
@@ -795,7 +796,7 @@ fn resolver_for_lowering_raw<'tcx>(
     } = resolver.into_outputs();
 
     let resolutions = tcx.arena.alloc(untracked_resolutions);
-    (tcx.arena.alloc(Steal::new((untracked_resolver_for_lowering, Arc::new(krate)))), resolutions)
+    (tcx.arena.alloc((untracked_resolver_for_lowering, Steal::new(krate))), resolutions)
 }
 
 pub fn write_dep_info(tcx: TyCtxt<'_>) {
@@ -852,10 +853,10 @@ pub fn write_interface<'tcx>(tcx: TyCtxt<'tcx>) {
         return;
     }
     let _timer = tcx.sess.timer("write_interface");
-    let (_, krate) = &*tcx.resolver_for_lowering().borrow();
+    let (_, krate) = tcx.resolver_for_lowering();
 
     let krate = rustc_ast_pretty::pprust::print_crate_as_interface(
-        krate,
+        &*krate.borrow(),
         tcx.sess.psess.edition,
         &tcx.sess.psess.attr_id_generator,
     );
@@ -869,7 +870,8 @@ pub fn write_interface<'tcx>(tcx: TyCtxt<'tcx>) {
 pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
     let providers = &mut Providers::default();
     providers.analysis = analysis;
-    providers.hir_crate = rustc_ast_lowering::lower_to_hir;
+    providers.index_ast = rustc_ast_lowering::index_ast;
+    providers.lower_to_hir = rustc_ast_lowering::lower_to_hir;
     providers.resolver_for_lowering_raw = resolver_for_lowering_raw;
     providers.stripped_cfg_items = |tcx, _| &tcx.resolutions(()).stripped_cfg_items[..];
     providers.resolutions = |tcx, ()| tcx.resolver_for_lowering_raw(()).1;
@@ -1021,6 +1023,8 @@ pub fn create_and_enter_global_ctxt<T, F: for<'tcx> FnOnce(TyCtxt<'tcx>) -> T>(
 /// Runs all analyses that we guarantee to run, even if errors were reported in earlier analyses.
 /// This function never fails.
 fn run_required_analyses(tcx: TyCtxt<'_>) {
+    tcx.ensure_done().early_lint_checks(());
+
     if tcx.sess.opts.unstable_opts.input_stats {
         rustc_passes::input_stats::print_hir_stats(tcx);
     }
diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 172f3372483ae..255ff56f62b1d 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -28,7 +28,7 @@ use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{CRATE_DEF_ID, DefId, LocalDefId};
 use rustc_hir::intravisit::FnKind as HirFnKind;
-use rustc_hir::{Body, FnDecl, GenericParamKind, PatKind, PredicateOrigin};
+use rustc_hir::{Body, FnDecl, PatKind, PredicateOrigin};
 use rustc_middle::bug;
 use rustc_middle::lint::LevelAndSource;
 use rustc_middle::ty::layout::LayoutOf;
@@ -952,36 +952,34 @@ declare_lint! {
 
 declare_lint_pass!(InvalidNoMangleItems => [NO_MANGLE_CONST_ITEMS, NO_MANGLE_GENERIC_ITEMS]);
 
+impl InvalidNoMangleItems {
+    fn check_no_mangle_on_generic_fn(
+        &self,
+        cx: &LateContext<'_>,
+        attr_span: Span,
+        def_id: LocalDefId,
+    ) {
+        let generics = cx.tcx.generics_of(def_id);
+        if generics.requires_monomorphization(cx.tcx) {
+            cx.emit_span_lint(
+                NO_MANGLE_GENERIC_ITEMS,
+                cx.tcx.def_span(def_id),
+                BuiltinNoMangleGeneric { suggestion: attr_span },
+            );
+        }
+    }
+}
+
 impl<'tcx> LateLintPass<'tcx> for InvalidNoMangleItems {
     fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
         let attrs = cx.tcx.hir_attrs(it.hir_id());
-        let check_no_mangle_on_generic_fn = |attr_span: Span,
-                                             impl_generics: Option<&hir::Generics<'_>>,
-                                             generics: &hir::Generics<'_>,
-                                             span| {
-            for param in
-                generics.params.iter().chain(impl_generics.map(|g| g.params).into_iter().flatten())
-            {
-                match param.kind {
-                    GenericParamKind::Lifetime { .. } => {}
-                    GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => {
-                        cx.emit_span_lint(
-                            NO_MANGLE_GENERIC_ITEMS,
-                            span,
-                            BuiltinNoMangleGeneric { suggestion: attr_span },
-                        );
-                        break;
-                    }
-                }
-            }
-        };
         match it.kind {
-            hir::ItemKind::Fn { generics, .. } => {
+            hir::ItemKind::Fn { .. } => {
                 if let Some(attr_span) =
                     find_attr!(attrs, AttributeKind::ExportName {span, ..} => *span)
                         .or_else(|| find_attr!(attrs, AttributeKind::NoMangle(span) => *span))
                 {
-                    check_no_mangle_on_generic_fn(attr_span, None, generics, it.span);
+                    self.check_no_mangle_on_generic_fn(cx, attr_span, it.owner_id.def_id);
                 }
             }
             hir::ItemKind::Const(..) => {
@@ -1006,24 +1004,19 @@ impl<'tcx> LateLintPass<'tcx> for InvalidNoMangleItems {
                     );
                 }
             }
-            hir::ItemKind::Impl(hir::Impl { generics, items, .. }) => {
-                for it in *items {
-                    if let hir::AssocItemKind::Fn { .. } = it.kind {
-                        let attrs = cx.tcx.hir_attrs(it.id.hir_id());
-                        if let Some(attr_span) =
-                            find_attr!(attrs, AttributeKind::ExportName {span, ..} => *span)
-                                .or_else(
-                                    || find_attr!(attrs, AttributeKind::NoMangle(span) => *span),
-                                )
-                        {
-                            check_no_mangle_on_generic_fn(
-                                attr_span,
-                                Some(generics),
-                                cx.tcx.hir_get_generics(it.id.owner_id.def_id).unwrap(),
-                                it.span,
-                            );
-                        }
-                    }
+            _ => {}
+        }
+    }
+
+    fn check_impl_item(&mut self, cx: &LateContext<'_>, it: &hir::ImplItem<'_>) {
+        let attrs = cx.tcx.hir_attrs(it.hir_id());
+        match it.kind {
+            hir::ImplItemKind::Fn { .. } => {
+                if let Some(attr_span) =
+                    find_attr!(attrs, AttributeKind::ExportName {span, ..} => *span)
+                        .or_else(|| find_attr!(attrs, AttributeKind::NoMangle(span) => *span))
+                {
+                    self.check_no_mangle_on_generic_fn(cx, attr_span, it.owner_id.def_id);
                 }
             }
             _ => {}
diff --git a/compiler/rustc_lint/src/deref_into_dyn_supertrait.rs b/compiler/rustc_lint/src/deref_into_dyn_supertrait.rs
index 5989ef9519cd7..dd16117db1c5e 100644
--- a/compiler/rustc_lint/src/deref_into_dyn_supertrait.rs
+++ b/compiler/rustc_lint/src/deref_into_dyn_supertrait.rs
@@ -1,7 +1,7 @@
 use rustc_hir::{self as hir, LangItem};
 use rustc_middle::ty;
 use rustc_session::{declare_lint, declare_lint_pass};
-use rustc_span::sym;
+use rustc_span::{Ident, sym};
 use rustc_trait_selection::traits::supertraits;
 
 use crate::lints::{SupertraitAsDerefTarget, SupertraitAsDerefTargetLabel};
@@ -79,11 +79,15 @@ impl<'tcx> LateLintPass<'tcx> for DerefIntoDynSupertrait {
             // erase regions in self type for better diagnostic presentation
             let (self_ty, target_principal, supertrait_principal) =
                 tcx.erase_regions((self_ty, target_principal, supertrait_principal));
-            let label2 = impl_
-                .items
-                .iter()
-                .find_map(|i| (i.ident.name == sym::Target).then_some(i.span))
-                .map(|label| SupertraitAsDerefTargetLabel { label });
+            let label2 = tcx
+                .associated_items(item.owner_id)
+                .find_by_ident_and_kind(
+                    tcx,
+                    Ident::with_dummy_span(sym::Target),
+                    ty::AssocTag::Type,
+                    item.owner_id.to_def_id(),
+                )
+                .map(|label| SupertraitAsDerefTargetLabel { label: tcx.def_span(label.def_id) });
             let span = tcx.def_span(item.owner_id.def_id);
             cx.emit_span_lint(
                 DEREF_INTO_DYN_SUPERTRAIT,
diff --git a/compiler/rustc_metadata/src/foreign_modules.rs b/compiler/rustc_metadata/src/foreign_modules.rs
index 24689ea61d036..8a6b2027083d6 100644
--- a/compiler/rustc_metadata/src/foreign_modules.rs
+++ b/compiler/rustc_metadata/src/foreign_modules.rs
@@ -19,7 +19,7 @@ pub(crate) fn collect(tcx: TyCtxt<'_>, LocalCrate: LocalCrate) -> FxIndexMap<Def
         let item = tcx.hir_item(id);
 
         if let hir::ItemKind::ForeignMod { abi, items } = item.kind {
-            let foreign_items = items.iter().map(|it| it.id.owner_id.to_def_id()).collect();
+            let foreign_items = items.iter().map(|it| it.owner_id.to_def_id()).collect();
             modules.insert(def_id, ForeignModule { def_id, abi, foreign_items });
         }
     }
diff --git a/compiler/rustc_middle/src/arena.rs b/compiler/rustc_middle/src/arena.rs
index a0f4597408939..563f1d7a30a2e 100644
--- a/compiler/rustc_middle/src/arena.rs
+++ b/compiler/rustc_middle/src/arena.rs
@@ -30,10 +30,16 @@ macro_rules! arena_types {
                 >,
             [decode] typeck_results: rustc_middle::ty::TypeckResults<'tcx>,
             [decode] borrowck_result: rustc_middle::mir::ConcreteOpaqueTypes<'tcx>,
-            [] resolver: rustc_data_structures::steal::Steal<(
+            [] resolver: (
                 rustc_middle::ty::ResolverAstLowering,
-                std::sync::Arc<rustc_ast::Crate>,
-            )>,
+                rustc_data_structures::steal::Steal<rustc_ast::Crate>
+            ),
+            [] index_ast: (
+                rustc_index::IndexVec<rustc_span::def_id::LocalDefId,
+                    rustc_data_structures::steal::Steal<rustc_ast::AstOwner>
+                >,
+                rustc_ast::NodeId,
+            ),
             [] crate_for_resolver: rustc_data_structures::steal::Steal<(rustc_ast::Crate, rustc_ast::AttrVec)>,
             [] resolutions: rustc_middle::ty::ResolverGlobalCtxt,
             [] const_allocs: rustc_middle::mir::interpret::Allocation,
diff --git a/compiler/rustc_middle/src/hir/map.rs b/compiler/rustc_middle/src/hir/map.rs
index 291707878a342..ad98a3fc355d2 100644
--- a/compiler/rustc_middle/src/hir/map.rs
+++ b/compiler/rustc_middle/src/hir/map.rs
@@ -1117,11 +1117,8 @@ impl<'tcx> pprust_hir::PpAnn for TyCtxt<'tcx> {
 }
 
 pub(super) fn crate_hash(tcx: TyCtxt<'_>, _: LocalCrate) -> Svh {
-    let krate = tcx.hir_crate(());
-    let hir_body_hash = krate.opt_hir_hash.expect("HIR hash missing while computing crate hash");
-
+    let krate = tcx.hir_crate_items(());
     let upstream_crates = upstream_crates(tcx);
-
     let resolutions = tcx.resolutions(());
 
     // We hash the final, remapped names of all local source files so we
@@ -1156,7 +1153,12 @@ pub(super) fn crate_hash(tcx: TyCtxt<'_>, _: LocalCrate) -> Svh {
 
     let crate_hash: Fingerprint = tcx.with_stable_hashing_context(|mut hcx| {
         let mut stable_hasher = StableHasher::new();
-        hir_body_hash.hash_stable(&mut hcx, &mut stable_hasher);
+        // hir_body_hash
+        for owner in krate.owners() {
+            if let Some(info) = tcx.lower_to_hir(owner.def_id).as_owner() {
+                info.hash_stable(&mut hcx, &mut stable_hasher);
+            }
+        }
         upstream_crates.hash_stable(&mut hcx, &mut stable_hasher);
         source_file_names.hash_stable(&mut hcx, &mut stable_hasher);
         debugger_visualizers.hash_stable(&mut hcx, &mut stable_hasher);
diff --git a/compiler/rustc_middle/src/hir/mod.rs b/compiler/rustc_middle/src/hir/mod.rs
index d7a8dce0536b2..01f80ef2fb339 100644
--- a/compiler/rustc_middle/src/hir/mod.rs
+++ b/compiler/rustc_middle/src/hir/mod.rs
@@ -208,19 +208,18 @@ pub fn provide(providers: &mut Providers) {
     providers.hir_crate_items = map::hir_crate_items;
     providers.crate_hash = map::crate_hash;
     providers.hir_module_items = map::hir_module_items;
-    providers.local_def_id_to_hir_id = |tcx, def_id| match tcx.hir_crate(()).owners[def_id] {
+    providers.local_def_id_to_hir_id = |tcx, def_id| match tcx.lower_to_hir(def_id) {
         MaybeOwner::Owner(_) => HirId::make_owner(def_id),
         MaybeOwner::NonOwner(hir_id) => hir_id,
-        MaybeOwner::Phantom => bug!("No HirId for {:?}", def_id),
     };
-    providers.opt_hir_owner_nodes =
-        |tcx, id| tcx.hir_crate(()).owners.get(id)?.as_owner().map(|i| &i.nodes);
+    providers.opt_hir_owner_nodes = |tcx, id| tcx.lower_to_hir(id).as_owner().map(|i| &i.nodes);
     providers.hir_owner_parent = |tcx, owner_id| {
         tcx.opt_local_parent(owner_id.def_id).map_or(CRATE_HIR_ID, |parent_def_id| {
             let parent_owner_id = tcx.local_def_id_to_hir_id(parent_def_id).owner;
             HirId {
                 owner: parent_owner_id,
-                local_id: tcx.hir_crate(()).owners[parent_owner_id.def_id]
+                local_id: tcx
+                    .lower_to_hir(parent_owner_id)
                     .unwrap()
                     .parenting
                     .get(&owner_id.def_id)
@@ -229,11 +228,10 @@ pub fn provide(providers: &mut Providers) {
             }
         })
     };
-    providers.hir_attr_map = |tcx, id| {
-        tcx.hir_crate(()).owners[id.def_id].as_owner().map_or(AttributeMap::EMPTY, |o| &o.attrs)
-    };
+    providers.hir_attr_map =
+        |tcx, id| tcx.lower_to_hir(id.def_id).as_owner().map_or(AttributeMap::EMPTY, |o| &o.attrs);
     providers.opt_ast_lowering_delayed_lints =
-        |tcx, id| tcx.hir_crate(()).owners[id.def_id].as_owner().map(|o| &o.delayed_lints);
+        |tcx, id| tcx.lower_to_hir(id.def_id).as_owner().map(|o| &o.delayed_lints);
     providers.def_span = |tcx, def_id| tcx.hir_span(tcx.local_def_id_to_hir_id(def_id));
     providers.def_ident_span = |tcx, def_id| {
         let hir_id = tcx.local_def_id_to_hir_id(def_id);
@@ -265,7 +263,6 @@ pub fn provide(providers: &mut Providers) {
         |tcx, trait_id| tcx.resolutions(()).trait_impls.get(&trait_id).map_or(&[], |xs| &xs[..]);
     providers.expn_that_defined =
         |tcx, id| tcx.resolutions(()).expn_that_defined.get(&id).copied().unwrap_or(ExpnId::root());
-    providers.in_scope_traits_map = |tcx, id| {
-        tcx.hir_crate(()).owners[id.def_id].as_owner().map(|owner_info| &owner_info.trait_map)
-    };
+    providers.in_scope_traits_map =
+        |tcx, id| tcx.lower_to_hir(id.def_id).as_owner().map(|owner_info| &owner_info.trait_map);
 }
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 17a29c9ae4b21..be02eb0b4b96f 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -83,7 +83,7 @@ use rustc_hir::def_id::{
     CrateNum, DefId, DefIdMap, LocalDefId, LocalDefIdMap, LocalDefIdSet, LocalModDefId,
 };
 use rustc_hir::lang_items::{LangItem, LanguageItems};
-use rustc_hir::{Crate, ItemLocalId, ItemLocalMap, PreciseCapturingArgKind, TraitCandidate};
+use rustc_hir::{ItemLocalId, ItemLocalMap, PreciseCapturingArgKind, TraitCandidate};
 use rustc_index::IndexVec;
 use rustc_lint_defs::LintId;
 use rustc_macros::rustc_queries;
@@ -198,12 +198,19 @@ rustc_queries! {
         desc { "getting the resolver outputs" }
     }
 
-    query resolver_for_lowering_raw(_: ()) -> (&'tcx Steal<(ty::ResolverAstLowering, Arc<ast::Crate>)>, &'tcx ty::ResolverGlobalCtxt) {
+    query resolver_for_lowering_raw(_: ()) -> (&'tcx (ty::ResolverAstLowering, Steal<ast::Crate>), &'tcx ty::ResolverGlobalCtxt) {
         eval_always
         no_hash
         desc { "getting the resolver for lowering" }
     }
 
+    query index_ast(_: ()) -> &'tcx (IndexVec<LocalDefId, Steal<ast::AstOwner>>, ast::NodeId) {
+        arena_cache
+        eval_always
+        no_hash
+        desc { "getting the AST for lowering" }
+    }
+
     /// Return the span for a definition.
     ///
     /// Contrary to `def_span` below, this query returns the full absolute span of the definition.
@@ -215,17 +222,9 @@ rustc_queries! {
         desc { "getting the source span" }
     }
 
-    /// Represents crate as a whole (as distinct from the top-level crate module).
-    ///
-    /// If you call `tcx.hir_crate(())` we will have to assume that any change
-    /// means that you need to be recompiled. This is because the `hir_crate`
-    /// query gives you access to all other items. To avoid this fate, do not
-    /// call `tcx.hir_crate(())`; instead, prefer wrappers like
-    /// [`TyCtxt::hir_visit_all_item_likes_in_crate`].
-    query hir_crate(key: ()) -> &'tcx Crate<'tcx> {
-        arena_cache
+    query lower_to_hir(key: LocalDefId) -> hir::MaybeOwner<'tcx> {
         eval_always
-        desc { "getting the crate HIR" }
+        desc { |tcx| "lower HIR for `{}`", tcx.def_path_str(key.to_def_id()) }
     }
 
     /// All items in the crate.
@@ -1839,8 +1838,7 @@ rustc_queries! {
     query specializes(_: (DefId, DefId)) -> bool {
         desc { "computing whether impls specialize one another" }
     }
-    query in_scope_traits_map(_: hir::OwnerId)
-        -> Option<&'tcx ItemLocalMap<Box<[TraitCandidate]>>> {
+    query in_scope_traits_map(_: hir::OwnerId) -> Option<&'tcx ItemLocalMap<&'tcx [TraitCandidate]>> {
         desc { "getting traits in scope at a block" }
     }
 
diff --git a/compiler/rustc_middle/src/ty/assoc.rs b/compiler/rustc_middle/src/ty/assoc.rs
index 78b2e265b488c..789c4d0f410a2 100644
--- a/compiler/rustc_middle/src/ty/assoc.rs
+++ b/compiler/rustc_middle/src/ty/assoc.rs
@@ -256,6 +256,16 @@ impl AssocItems {
         self.items.get_by_key(Some(name))
     }
 
+    /// Returns the associated item with the given identifier and `AssocKind`, if one exists.
+    /// The identifier is ignoring hygiene. This is meant to be used for lints and diagnostics.
+    pub fn filter_by_name_unhygienic_and_kind(
+        &self,
+        name: Symbol,
+        assoc_tag: AssocTag,
+    ) -> impl '_ + Iterator<Item = &ty::AssocItem> {
+        self.filter_by_name_unhygienic(name).filter(move |item| item.as_tag() == assoc_tag)
+    }
+
     /// Returns the associated item with the given identifier and `AssocKind`, if one exists.
     /// The identifier is matched hygienically.
     pub fn find_by_ident_and_kind(
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 98b2ce01d89b2..2361538ac7b09 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -1352,11 +1352,11 @@ impl<'tcx> TyCtxtFeed<'tcx, LocalDefId> {
         let bodies = Default::default();
         let attrs = hir::AttributeMap::EMPTY;
 
-        let (opt_hash_including_bodies, _, _) =
+        let (opt_hash, _, _) =
             self.tcx.hash_owner_nodes(node, &bodies, &attrs.map, &[], attrs.define_opaque);
         let node = node.into();
         self.opt_hir_owner_nodes(Some(self.tcx.arena.alloc(hir::OwnerNodes {
-            opt_hash_including_bodies,
+            opt_hash,
             nodes: IndexVec::from_elem_n(
                 hir::ParentedNode { parent: hir::ItemLocalId::INVALID, node },
                 1,
@@ -3357,7 +3357,7 @@ impl<'tcx> TyCtxt<'tcx> {
         self.resolutions(()).module_children.get(&def_id).map_or(&[], |v| &v[..])
     }
 
-    pub fn resolver_for_lowering(self) -> &'tcx Steal<(ty::ResolverAstLowering, Arc<ast::Crate>)> {
+    pub fn resolver_for_lowering(self) -> &'tcx (ty::ResolverAstLowering, Steal<ast::Crate>) {
         self.resolver_for_lowering_raw(()).0
     }
 
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index f1b16ea54e634..e18fc51544fbf 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -38,7 +38,6 @@ use rustc_errors::{Diag, ErrorGuaranteed};
 use rustc_hir::LangItem;
 use rustc_hir::def::{CtorKind, CtorOf, DefKind, DocLinkResMap, LifetimeRes, Res};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, LocalDefIdMap};
-use rustc_hir::definitions::DisambiguatorState;
 use rustc_index::IndexVec;
 use rustc_index::bit_set::BitMatrix;
 use rustc_macros::{
@@ -221,8 +220,6 @@ pub struct ResolverAstLowering {
 
     pub node_id_to_def_id: NodeMap<LocalDefId>,
 
-    pub disambiguator: DisambiguatorState,
-
     pub trait_map: NodeMap<Vec<hir::TraitCandidate>>,
     /// List functions and methods for which lifetime elision was successful.
     pub lifetime_elision_allowed: FxHashSet<ast::NodeId>,
@@ -1593,7 +1590,8 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 
     /// Look up the name of a definition across crates. This does not look at HIR.
-    pub fn opt_item_name(self, def_id: DefId) -> Option<Symbol> {
+    pub fn opt_item_name(self, def_id: impl IntoQueryParam<DefId>) -> Option<Symbol> {
+        let def_id = def_id.into_query_param();
         if let Some(cnum) = def_id.as_crate_root() {
             Some(self.crate_name(cnum))
         } else {
@@ -1613,7 +1611,8 @@ impl<'tcx> TyCtxt<'tcx> {
     /// [`opt_item_name`] instead.
     ///
     /// [`opt_item_name`]: Self::opt_item_name
-    pub fn item_name(self, id: DefId) -> Symbol {
+    pub fn item_name(self, id: impl IntoQueryParam<DefId>) -> Symbol {
+        let id = id.into_query_param();
         self.opt_item_name(id).unwrap_or_else(|| {
             bug!("item_name: no name for {:?}", self.def_path(id));
         })
@@ -1622,7 +1621,8 @@ impl<'tcx> TyCtxt<'tcx> {
     /// Look up the name and span of a definition.
     ///
     /// See [`item_name`][Self::item_name] for more information.
-    pub fn opt_item_ident(self, def_id: DefId) -> Option<Ident> {
+    pub fn opt_item_ident(self, def_id: impl IntoQueryParam<DefId>) -> Option<Ident> {
+        let def_id = def_id.into_query_param();
         let def = self.opt_item_name(def_id)?;
         let span = self
             .def_ident_span(def_id)
@@ -1633,7 +1633,8 @@ impl<'tcx> TyCtxt<'tcx> {
     /// Look up the name and span of a definition.
     ///
     /// See [`item_name`][Self::item_name] for more information.
-    pub fn item_ident(self, def_id: DefId) -> Ident {
+    pub fn item_ident(self, def_id: impl IntoQueryParam<DefId>) -> Ident {
+        let def_id = def_id.into_query_param();
         self.opt_item_ident(def_id).unwrap_or_else(|| {
             bug!("item_ident: no name for {:?}", self.def_path(def_id));
         })
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 1dba4a7b040a7..21f22876a6c03 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -2186,6 +2186,7 @@ fn guess_def_namespace(tcx: TyCtxt<'_>, def_id: DefId) -> Namespace {
 
         DefPathData::ValueNs(..)
         | DefPathData::AnonConst
+        | DefPathData::LateAnonConst
         | DefPathData::Closure
         | DefPathData::Ctor => Namespace::ValueNS,
 
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
index 69b8be3d9cbc3..24833d3138485 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -1681,7 +1681,7 @@ pub fn intrinsic_raw(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<ty::Intrinsi
             _ => true,
         };
         Some(ty::IntrinsicDef {
-            name: tcx.item_name(def_id.into()),
+            name: tcx.item_name(def_id),
             must_be_overridden,
             const_stable: tcx.has_attr(def_id, sym::rustc_intrinsic_const_stable_indirect),
         })
diff --git a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
index b7b160c738d22..fab4434bc3478 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
@@ -1083,7 +1083,7 @@ fn find_fallback_pattern_typo<'tcx>(
                 && infcx.can_eq(param_env, ty, cx.tcx.type_of(item.owner_id).instantiate_identity())
             {
                 // Look for local consts.
-                let item_name = cx.tcx.item_name(item.owner_id.into());
+                let item_name = cx.tcx.item_name(item.owner_id);
                 let vis = cx.tcx.visibility(item.owner_id);
                 if vis.is_accessible_from(parent, cx.tcx) {
                     accessible.push(item_name);
diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index f253d1662cac8..221bd7516732e 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -327,7 +327,7 @@ fn extract_hir_info<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> ExtractedHir
 fn hash_mir_source<'tcx>(tcx: TyCtxt<'tcx>, hir_body: &'tcx hir::Body<'tcx>) -> u64 {
     // FIXME(cjgillot) Stop hashing HIR manually here.
     let owner = hir_body.id().hir_id.owner;
-    tcx.hir_owner_nodes(owner).opt_hash_including_bodies.unwrap().to_smaller_hash().as_u64()
+    tcx.hir_owner_nodes(owner).opt_hash.unwrap().to_smaller_hash().as_u64()
 }
 
 fn extract_hole_spans_from_hir<'tcx>(tcx: TyCtxt<'tcx>, hir_body: &hir::Body<'tcx>) -> Vec<Span> {
diff --git a/compiler/rustc_passes/src/abi_test.rs b/compiler/rustc_passes/src/abi_test.rs
index b139ed6a66c38..0ac42f03eb2f5 100644
--- a/compiler/rustc_passes/src/abi_test.rs
+++ b/compiler/rustc_passes/src/abi_test.rs
@@ -79,7 +79,7 @@ fn dump_abi_of_fn_item(tcx: TyCtxt<'_>, item_def_id: LocalDefId, attr: &Attribut
     for meta_item in meta_items {
         match meta_item.name() {
             Some(sym::debug) => {
-                let fn_name = tcx.item_name(item_def_id.into());
+                let fn_name = tcx.item_name(item_def_id);
                 tcx.dcx().emit_err(AbiOf {
                     span: tcx.def_span(item_def_id),
                     fn_name,
@@ -135,7 +135,7 @@ fn dump_abi_of_fn_type(tcx: TyCtxt<'_>, item_def_id: LocalDefId, attr: &Attribut
                     item_def_id,
                 );
 
-                let fn_name = tcx.item_name(item_def_id.into());
+                let fn_name = tcx.item_name(item_def_id);
                 tcx.dcx().emit_err(AbiOf { span, fn_name, fn_abi: format!("{:#?}", abi) });
             }
             Some(sym::assert_eq) => {
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index c5ced4064140e..874fd4d430e99 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -18,8 +18,8 @@ use rustc_hir::def::DefKind;
 use rustc_hir::def_id::LocalModDefId;
 use rustc_hir::intravisit::{self, Visitor};
 use rustc_hir::{
-    self as hir, self, AssocItemKind, Attribute, CRATE_HIR_ID, CRATE_OWNER_ID, FnSig, ForeignItem,
-    HirId, Item, ItemKind, MethodKind, Safety, Target, TraitItem,
+    self as hir, self, Attribute, CRATE_HIR_ID, CRATE_OWNER_ID, FnSig, ForeignItem, HirId, Item,
+    ItemKind, MethodKind, Safety, Target, TraitItem,
 };
 use rustc_macros::LintDiagnostic;
 use rustc_middle::hir::nested_filter;
@@ -1119,7 +1119,9 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 if generics.params.len() != 0 => {}
             ItemKind::Trait(_, _, _, generics, _, items)
                 if generics.params.len() != 0
-                    || items.iter().any(|item| matches!(item.kind, AssocItemKind::Type)) => {}
+                    || items.iter().any(|item| {
+                        matches!(self.tcx.def_kind(item.owner_id), DefKind::AssocTy)
+                    }) => {}
             ItemKind::TyAlias(_, generics, _) if generics.params.len() != 0 => {}
             _ => {
                 self.dcx().emit_err(errors::DocSearchUnboxInvalid { span: meta.span() });
diff --git a/compiler/rustc_passes/src/dead.rs b/compiler/rustc_passes/src/dead.rs
index cdfd1a2b07e34..948a901e091ed 100644
--- a/compiler/rustc_passes/src/dead.rs
+++ b/compiler/rustc_passes/src/dead.rs
@@ -415,8 +415,8 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
                 hir::ItemKind::Trait(.., trait_item_refs) => {
                     // mark assoc ty live if the trait is live
                     for trait_item in trait_item_refs {
-                        if matches!(trait_item.kind, hir::AssocItemKind::Type) {
-                            self.check_def_id(trait_item.id.owner_id.to_def_id());
+                        if matches!(self.tcx.def_kind(trait_item.owner_id), DefKind::AssocTy) {
+                            self.check_def_id(trait_item.owner_id.to_def_id());
                         }
                     }
                     intravisit::walk_item(self, item)
diff --git a/compiler/rustc_passes/src/debugger_visualizer.rs b/compiler/rustc_passes/src/debugger_visualizer.rs
index 7a7a8175e5569..067b28e141f6a 100644
--- a/compiler/rustc_passes/src/debugger_visualizer.rs
+++ b/compiler/rustc_passes/src/debugger_visualizer.rs
@@ -82,11 +82,10 @@ impl<'ast> rustc_ast::visit::Visitor<'ast> for DebuggerVisualizerCollector<'_> {
 
 /// Traverses and collects the debugger visualizers for a specific crate.
 fn debugger_visualizers(tcx: TyCtxt<'_>, _: LocalCrate) -> Vec<DebuggerVisualizerFile> {
-    let resolver_and_krate = tcx.resolver_for_lowering().borrow();
-    let krate = &*resolver_and_krate.1;
+    let krate = &tcx.resolver_for_lowering().1;
 
     let mut visitor = DebuggerVisualizerCollector { sess: tcx.sess, visualizers: Vec::new() };
-    rustc_ast::visit::Visitor::visit_crate(&mut visitor, krate);
+    rustc_ast::visit::Visitor::visit_crate(&mut visitor, &*krate.borrow());
 
     // We are collecting visualizers in AST-order, which is deterministic,
     // so we don't need to do any explicit sorting in order to get a
diff --git a/compiler/rustc_passes/src/input_stats.rs b/compiler/rustc_passes/src/input_stats.rs
index 40bc18939d636..1719f9867f46a 100644
--- a/compiler/rustc_passes/src/input_stats.rs
+++ b/compiler/rustc_passes/src/input_stats.rs
@@ -467,9 +467,9 @@ impl<'v> hir_visit::Visitor<'v> for StatCollector<'v> {
         hir_visit::walk_trait_item(self, ti)
     }
 
-    fn visit_trait_item_ref(&mut self, ti: &'v hir::TraitItemRef) {
-        self.record("TraitItemRef", Some(ti.id.hir_id()), ti);
-        hir_visit::walk_trait_item_ref(self, ti)
+    fn visit_trait_item_ref(&mut self, ti: &'v hir::TraitItemId) {
+        self.record("TraitItemId", Some(ti.hir_id()), ti);
+        hir_visit::walk_trait_item_ref(self, *ti)
     }
 
     fn visit_impl_item(&mut self, ii: &'v hir::ImplItem<'v>) {
@@ -480,14 +480,14 @@ impl<'v> hir_visit::Visitor<'v> for StatCollector<'v> {
         hir_visit::walk_impl_item(self, ii)
     }
 
-    fn visit_foreign_item_ref(&mut self, fi: &'v hir::ForeignItemRef) {
-        self.record("ForeignItemRef", Some(fi.id.hir_id()), fi);
-        hir_visit::walk_foreign_item_ref(self, fi)
+    fn visit_foreign_item_ref(&mut self, fi: &'v hir::ForeignItemId) {
+        self.record("ForeignItemId", Some(fi.hir_id()), fi);
+        hir_visit::walk_foreign_item_ref(self, *fi)
     }
 
-    fn visit_impl_item_ref(&mut self, ii: &'v hir::ImplItemRef) {
-        self.record("ImplItemRef", Some(ii.id.hir_id()), ii);
-        hir_visit::walk_impl_item_ref(self, ii)
+    fn visit_impl_item_ref(&mut self, ii: &'v hir::ImplItemId) {
+        self.record("ImplItemId", Some(ii.hir_id()), ii);
+        hir_visit::walk_impl_item_ref(self, *ii)
     }
 
     fn visit_param_bound(&mut self, b: &'v hir::GenericBound<'v>) {
diff --git a/compiler/rustc_passes/src/lang_items.rs b/compiler/rustc_passes/src/lang_items.rs
index 3afed9784de51..cb2e702276a13 100644
--- a/compiler/rustc_passes/src/lang_items.rs
+++ b/compiler/rustc_passes/src/lang_items.rs
@@ -247,8 +247,8 @@ impl<'ast, 'tcx> LanguageItemCollector<'ast, 'tcx> {
 
 /// Traverses and collects all the lang items in all crates.
 fn get_lang_items(tcx: TyCtxt<'_>, (): ()) -> LanguageItems {
-    let resolver = tcx.resolver_for_lowering().borrow();
-    let (resolver, krate) = &*resolver;
+    let (resolver, krate) = tcx.resolver_for_lowering();
+    let krate = &*krate.borrow();
 
     // Initialize the collector.
     let mut collector = LanguageItemCollector::new(tcx, resolver);
diff --git a/compiler/rustc_passes/src/stability.rs b/compiler/rustc_passes/src/stability.rs
index 56d9f5bf78577..802cbb9fa2036 100644
--- a/compiler/rustc_passes/src/stability.rs
+++ b/compiler/rustc_passes/src/stability.rs
@@ -880,11 +880,16 @@ impl<'tcx> Visitor<'tcx> for Checker<'tcx> {
                 }
 
                 for impl_item_ref in *items {
-                    let impl_item = self.tcx.associated_item(impl_item_ref.id.owner_id);
+                    let impl_item = self.tcx.associated_item(impl_item_ref.owner_id);
 
                     if let Some(def_id) = impl_item.trait_item_def_id {
                         // Pass `None` to skip deprecation warnings.
-                        self.tcx.check_stability(def_id, None, impl_item_ref.span, None);
+                        self.tcx.check_stability(
+                            def_id,
+                            None,
+                            self.tcx.def_span(impl_item_ref.owner_id),
+                            None,
+                        );
                     }
                 }
             }
diff --git a/compiler/rustc_privacy/src/lib.rs b/compiler/rustc_privacy/src/lib.rs
index 963f4c77d809d..ab2433234aa90 100644
--- a/compiler/rustc_privacy/src/lib.rs
+++ b/compiler/rustc_privacy/src/lib.rs
@@ -26,7 +26,7 @@ use rustc_errors::{MultiSpan, listify};
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{CRATE_DEF_ID, DefId, LocalDefId, LocalModDefId};
 use rustc_hir::intravisit::{self, InferKind, Visitor};
-use rustc_hir::{AmbigArg, AssocItemKind, ForeignItemKind, ItemId, ItemKind, PatKind};
+use rustc_hir::{AmbigArg, ForeignItemKind, ItemId, ItemKind, PatKind};
 use rustc_middle::middle::privacy::{EffectiveVisibilities, EffectiveVisibility, Level};
 use rustc_middle::query::Providers;
 use rustc_middle::ty::print::PrintTraitRefExt as _;
@@ -672,14 +672,14 @@ impl<'tcx> Visitor<'tcx> for EmbargoVisitor<'tcx> {
                     self.reach(item.owner_id.def_id, item_ev).generics().predicates();
 
                     for trait_item_ref in trait_item_refs {
-                        self.update(trait_item_ref.id.owner_id.def_id, item_ev, Level::Reachable);
+                        self.update(trait_item_ref.owner_id.def_id, item_ev, Level::Reachable);
 
                         let tcx = self.tcx;
-                        let mut reach = self.reach(trait_item_ref.id.owner_id.def_id, item_ev);
+                        let mut reach = self.reach(trait_item_ref.owner_id.def_id, item_ev);
                         reach.generics().predicates();
 
-                        if trait_item_ref.kind == AssocItemKind::Type
-                            && !tcx.defaultness(trait_item_ref.id.owner_id).has_value()
+                        if let DefKind::AssocTy = tcx.def_kind(trait_item_ref.owner_id)
+                            && !tcx.defaultness(trait_item_ref.owner_id).has_value()
                         {
                             // No type to visit.
                         } else {
@@ -715,7 +715,7 @@ impl<'tcx> Visitor<'tcx> for EmbargoVisitor<'tcx> {
                 self.reach(item.owner_id.def_id, item_ev).generics().predicates().ty().trait_ref();
 
                 for impl_item_ref in impl_.items {
-                    let def_id = impl_item_ref.id.owner_id.def_id;
+                    let def_id = impl_item_ref.owner_id.def_id;
                     let max_vis =
                         impl_.of_trait.is_none().then(|| self.tcx.local_visibility(def_id));
                     self.update_eff_vis(def_id, item_ev, max_vis, Level::Direct);
@@ -755,8 +755,8 @@ impl<'tcx> Visitor<'tcx> for EmbargoVisitor<'tcx> {
             }
             hir::ItemKind::ForeignMod { items, .. } => {
                 for foreign_item in items {
-                    if let Some(foreign_item_ev) = self.get(foreign_item.id.owner_id.def_id) {
-                        self.reach(foreign_item.id.owner_id.def_id, foreign_item_ev)
+                    if let Some(foreign_item_ev) = self.get(foreign_item.owner_id.def_id) {
+                        self.reach(foreign_item.owner_id.def_id, foreign_item_ev)
                             .generics()
                             .predicates()
                             .ty();
@@ -1576,16 +1576,15 @@ impl<'tcx> PrivateItemsInPublicInterfacesChecker<'_, 'tcx> {
 
     fn check_assoc_item(
         &self,
-        def_id: LocalDefId,
-        assoc_item_kind: AssocItemKind,
+        item: &ty::AssocItem,
         vis: ty::Visibility,
         effective_vis: Option<EffectiveVisibility>,
     ) {
-        let mut check = self.check(def_id, vis, effective_vis);
+        let mut check = self.check(item.def_id.expect_local(), vis, effective_vis);
 
-        let (check_ty, is_assoc_ty) = match assoc_item_kind {
-            AssocItemKind::Const | AssocItemKind::Fn { .. } => (true, false),
-            AssocItemKind::Type => (self.tcx.defaultness(def_id).has_value(), true),
+        let (check_ty, is_assoc_ty) = match item.kind {
+            ty::AssocKind::Const { .. } | ty::AssocKind::Fn { .. } => (true, false),
+            ty::AssocKind::Type { .. } => (item.defaultness(self.tcx).has_value(), true),
         };
 
         check.in_assoc_ty = is_assoc_ty;
@@ -1619,30 +1618,20 @@ impl<'tcx> PrivateItemsInPublicInterfacesChecker<'_, 'tcx> {
                 self.check(def_id, item_visibility, effective_vis).generics().bounds();
             }
             DefKind::Trait => {
-                let item = tcx.hir_item(id);
-                if let hir::ItemKind::Trait(.., trait_item_refs) = item.kind {
-                    self.check_unnameable(item.owner_id.def_id, effective_vis);
+                self.check_unnameable(def_id, effective_vis);
 
-                    self.check(item.owner_id.def_id, item_visibility, effective_vis)
-                        .generics()
-                        .predicates();
+                self.check(def_id, item_visibility, effective_vis).generics().predicates();
 
-                    for trait_item_ref in trait_item_refs {
-                        self.check_assoc_item(
-                            trait_item_ref.id.owner_id.def_id,
-                            trait_item_ref.kind,
+                for assoc_item in tcx.associated_items(id.owner_id).in_definition_order() {
+                    self.check_assoc_item(assoc_item, item_visibility, effective_vis);
+
+                    if assoc_item.is_type() {
+                        self.check(
+                            assoc_item.def_id.expect_local(),
                             item_visibility,
                             effective_vis,
-                        );
-
-                        if let AssocItemKind::Type = trait_item_ref.kind {
-                            self.check(
-                                trait_item_ref.id.owner_id.def_id,
-                                item_visibility,
-                                effective_vis,
-                            )
-                            .bounds();
-                        }
+                        )
+                        .bounds();
                     }
                 }
             }
@@ -1669,8 +1658,8 @@ impl<'tcx> PrivateItemsInPublicInterfacesChecker<'_, 'tcx> {
             DefKind::ForeignMod => {
                 let item = tcx.hir_item(id);
                 if let hir::ItemKind::ForeignMod { items, .. } = item.kind {
-                    for foreign_item in items {
-                        let foreign_item = tcx.hir_foreign_item(foreign_item.id);
+                    for &foreign_item in items {
+                        let foreign_item = tcx.hir_foreign_item(foreign_item);
 
                         let ev = self.get(foreign_item.owner_id.def_id);
                         let vis = tcx.local_visibility(foreign_item.owner_id.def_id);
@@ -1714,69 +1703,52 @@ impl<'tcx> PrivateItemsInPublicInterfacesChecker<'_, 'tcx> {
             // Subitems of inherent impls have their own publicity.
             // A trait impl is public when both its type and its trait are public
             // Subitems of trait impls have inherited publicity.
-            DefKind::Impl { .. } => {
-                let item = tcx.hir_item(id);
-                if let hir::ItemKind::Impl(impl_) = item.kind {
-                    let impl_vis = ty::Visibility::of_impl::<false>(
-                        item.owner_id.def_id,
-                        tcx,
-                        &Default::default(),
-                    );
+            DefKind::Impl { of_trait } => {
+                let impl_vis = ty::Visibility::of_impl::<false>(def_id, tcx, &Default::default());
 
-                    // We are using the non-shallow version here, unlike when building the
-                    // effective visisibilities table to avoid large number of false positives.
-                    // For example in
-                    //
-                    // impl From<Priv> for Pub {
-                    //     fn from(_: Priv) -> Pub {...}
-                    // }
-                    //
-                    // lints shouldn't be emitted even if `from` effective visibility
-                    // is larger than `Priv` nominal visibility and if `Priv` can leak
-                    // in some scenarios due to type inference.
-                    let impl_ev = EffectiveVisibility::of_impl::<false>(
-                        item.owner_id.def_id,
-                        tcx,
-                        self.effective_visibilities,
-                    );
+                // We are using the non-shallow version here, unlike when building the
+                // effective visisibilities table to avoid large number of false positives.
+                // For example in
+                //
+                // impl From<Priv> for Pub {
+                //     fn from(_: Priv) -> Pub {...}
+                // }
+                //
+                // lints shouldn't be emitted even if `from` effective visibility
+                // is larger than `Priv` nominal visibility and if `Priv` can leak
+                // in some scenarios due to type inference.
+                let impl_ev =
+                    EffectiveVisibility::of_impl::<false>(def_id, tcx, self.effective_visibilities);
+
+                let mut check = self.check(def_id, impl_vis, Some(impl_ev));
+
+                // Generics and predicates of trait impls are intentionally not checked
+                // for private components (#90586).
+                if !of_trait {
+                    check.generics().predicates();
+                }
 
-                    let mut check = self.check(item.owner_id.def_id, impl_vis, Some(impl_ev));
-                    // Generics and predicates of trait impls are intentionally not checked
-                    // for private components (#90586).
-                    if impl_.of_trait.is_none() {
-                        check.generics().predicates();
-                    }
-                    // Skip checking private components in associated types, due to lack of full
-                    // normalization they produce very ridiculous false positives.
-                    // FIXME: Remove this when full normalization is implemented.
-                    check.skip_assoc_tys = true;
-                    check.ty().trait_ref();
-
-                    for impl_item_ref in impl_.items {
-                        let impl_item_vis = if impl_.of_trait.is_none() {
-                            min(
-                                tcx.local_visibility(impl_item_ref.id.owner_id.def_id),
-                                impl_vis,
-                                tcx,
-                            )
-                        } else {
-                            impl_vis
-                        };
+                // Skip checking private components in associated types, due to lack of full
+                // normalization they produce very ridiculous false positives.
+                // FIXME: Remove this when full normalization is implemented.
+                check.skip_assoc_tys = true;
+                check.ty().trait_ref();
 
-                        let impl_item_ev = if impl_.of_trait.is_none() {
-                            self.get(impl_item_ref.id.owner_id.def_id)
-                                .map(|ev| ev.min(impl_ev, self.tcx))
-                        } else {
-                            Some(impl_ev)
-                        };
-
-                        self.check_assoc_item(
-                            impl_item_ref.id.owner_id.def_id,
-                            impl_item_ref.kind,
-                            impl_item_vis,
-                            impl_item_ev,
-                        );
-                    }
+                for assoc_item in tcx.associated_items(id.owner_id).in_definition_order() {
+                    let impl_item_vis = if !of_trait {
+                        min(tcx.local_visibility(assoc_item.def_id.expect_local()), impl_vis, tcx)
+                    } else {
+                        impl_vis
+                    };
+
+                    let impl_item_ev = if !of_trait {
+                        self.get(assoc_item.def_id.expect_local())
+                            .map(|ev| ev.min(impl_ev, self.tcx))
+                    } else {
+                        Some(impl_ev)
+                    };
+
+                    self.check_assoc_item(assoc_item, impl_item_vis, impl_item_ev);
                 }
             }
             _ => {}
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 7162f3a77d350..9d8b30ea6fca3 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -1693,7 +1693,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 .into_items()
                 .map(|(k, f)| (k, f.key()))
                 .collect(),
-            disambiguator: self.disambiguator,
             trait_map: self.trait_map,
             lifetime_elision_allowed: self.lifetime_elision_allowed,
             lint_buffer: Steal::new(self.lint_buffer),
diff --git a/compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/encode.rs b/compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/encode.rs
index f4a14b36ce5cf..b85dd73498135 100644
--- a/compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/encode.rs
+++ b/compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/encode.rs
@@ -713,7 +713,8 @@ fn encode_ty_name(tcx: TyCtxt<'_>, def_id: DefId) -> String {
             hir::definitions::DefPathData::ValueNs(..) => "v",
             hir::definitions::DefPathData::Closure => "C",
             hir::definitions::DefPathData::Ctor => "c",
-            hir::definitions::DefPathData::AnonConst => "k",
+            hir::definitions::DefPathData::AnonConst => "K",
+            hir::definitions::DefPathData::LateAnonConst => "k",
             hir::definitions::DefPathData::OpaqueTy => "i",
             hir::definitions::DefPathData::SyntheticCoroutineBody => "s",
             hir::definitions::DefPathData::NestedStatic => "n",
@@ -723,6 +724,7 @@ fn encode_ty_name(tcx: TyCtxt<'_>, def_id: DefId) -> String {
             | hir::definitions::DefPathData::MacroNs(..)
             | hir::definitions::DefPathData::OpaqueLifetime(..)
             | hir::definitions::DefPathData::LifetimeNs(..)
+            | hir::definitions::DefPathData::DesugaredAnonymousLifetime
             | hir::definitions::DefPathData::AnonAssocTy(..) => {
                 bug!("encode_ty_name: unexpected `{:?}`", disambiguated_data.data);
             }
diff --git a/compiler/rustc_span/src/def_id.rs b/compiler/rustc_span/src/def_id.rs
index 641bac88ad025..089042fac3dea 100644
--- a/compiler/rustc_span/src/def_id.rs
+++ b/compiler/rustc_span/src/def_id.rs
@@ -110,6 +110,7 @@ impl DefPathHash {
 
     /// Builds a new [DefPathHash] with the given [StableCrateId] and
     /// `local_hash`, where `local_hash` must be unique within its crate.
+    #[inline]
     pub fn new(stable_crate_id: StableCrateId, local_hash: Hash64) -> DefPathHash {
         DefPathHash(Fingerprint::new(stable_crate_id.0, local_hash))
     }
@@ -404,21 +405,21 @@ rustc_data_structures::define_id_collections!(
 impl<CTX: HashStableContext> HashStable<CTX> for DefId {
     #[inline]
     fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
-        self.to_stable_hash_key(hcx).hash_stable(hcx, hasher);
+        hcx.def_path_hash(*self).hash_stable(hcx, hasher);
     }
 }
 
 impl<CTX: HashStableContext> HashStable<CTX> for LocalDefId {
     #[inline]
     fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
-        self.to_stable_hash_key(hcx).hash_stable(hcx, hasher);
+        hcx.def_path_hash(self.to_def_id()).local_hash().hash_stable(hcx, hasher);
     }
 }
 
 impl<CTX: HashStableContext> HashStable<CTX> for CrateNum {
     #[inline]
     fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
-        self.to_stable_hash_key(hcx).hash_stable(hcx, hasher);
+        self.as_def_id().to_stable_hash_key(hcx).stable_crate_id().hash_stable(hcx, hasher);
     }
 }
 
diff --git a/compiler/rustc_symbol_mangling/src/v0.rs b/compiler/rustc_symbol_mangling/src/v0.rs
index fe0f8e6113ef7..eb679fb59790f 100644
--- a/compiler/rustc_symbol_mangling/src/v0.rs
+++ b/compiler/rustc_symbol_mangling/src/v0.rs
@@ -872,7 +872,8 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
             DefPathData::ValueNs(_) => 'v',
             DefPathData::Closure => 'C',
             DefPathData::Ctor => 'c',
-            DefPathData::AnonConst => 'k',
+            DefPathData::AnonConst => 'K',
+            DefPathData::LateAnonConst => 'k',
             DefPathData::OpaqueTy => 'i',
             DefPathData::SyntheticCoroutineBody => 's',
             DefPathData::NestedStatic => 'n',
@@ -884,6 +885,7 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
             | DefPathData::Impl
             | DefPathData::MacroNs(_)
             | DefPathData::LifetimeNs(_)
+            | DefPathData::DesugaredAnonymousLifetime
             | DefPathData::OpaqueLifetime(_)
             | DefPathData::AnonAssocTy(..) => {
                 bug!("symbol_names: unexpected DefPathData: {:?}", disambiguated_data.data)
diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/note_and_explain.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/note_and_explain.rs
index bff5e9128cbf1..db35c988bf7fa 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/infer/note_and_explain.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/infer/note_and_explain.rs
@@ -841,54 +841,32 @@ fn foo(&self) -> Self::T { String::new() }
 
         let param_env = tcx.param_env(body_owner_def_id);
 
-        match item {
-            hir::Node::Item(hir::Item { kind: hir::ItemKind::Trait(.., items), .. }) => {
-                // FIXME: account for `#![feature(specialization)]`
-                for item in &items[..] {
-                    match item.kind {
-                        hir::AssocItemKind::Type => {
-                            // FIXME: account for returning some type in a trait fn impl that has
-                            // an assoc type as a return type (#72076).
-                            if let hir::Defaultness::Default { has_value: true } =
-                                tcx.defaultness(item.id.owner_id)
-                            {
-                                let assoc_ty = tcx.type_of(item.id.owner_id).instantiate_identity();
-                                if self.infcx.can_eq(param_env, assoc_ty, found) {
-                                    diag.span_label(
-                                        item.span,
-                                        "associated type defaults can't be assumed inside the \
-                                            trait defining them",
-                                    );
-                                    return true;
-                                }
-                            }
+        if let DefKind::Trait | DefKind::Impl { .. } = tcx.def_kind(parent_id) {
+            let assoc_items = tcx.associated_items(parent_id);
+            // FIXME: account for `#![feature(specialization)]`
+            for assoc_item in assoc_items.in_definition_order() {
+                if assoc_item.is_type()
+                    // FIXME: account for returning some type in a trait fn impl that has
+                    // an assoc type as a return type (#72076).
+                    && let hir::Defaultness::Default { has_value: true } = assoc_item.defaultness(tcx)
+                    && let assoc_ty = tcx.type_of(assoc_item.def_id).instantiate_identity()
+                    && self.infcx.can_eq(param_env, assoc_ty, found)
+                {
+                    let msg = match assoc_item.container {
+                        ty::AssocItemContainer::Trait => {
+                            "associated type defaults can't be assumed inside the \
+                                            trait defining them"
                         }
-                        _ => {}
-                    }
-                }
-            }
-            hir::Node::Item(hir::Item {
-                kind: hir::ItemKind::Impl(hir::Impl { items, .. }),
-                ..
-            }) => {
-                for item in &items[..] {
-                    if let hir::AssocItemKind::Type = item.kind {
-                        let assoc_ty = tcx.type_of(item.id.owner_id).instantiate_identity();
-                        if let hir::Defaultness::Default { has_value: true } =
-                            tcx.defaultness(item.id.owner_id)
-                            && self.infcx.can_eq(param_env, assoc_ty, found)
-                        {
-                            diag.span_label(
-                                item.span,
-                                "associated type is `default` and may be overridden",
-                            );
-                            return true;
+                        ty::AssocItemContainer::Impl => {
+                            "associated type is `default` and may be overridden"
                         }
-                    }
+                    };
+                    diag.span_label(tcx.def_span(assoc_item.def_id), msg);
+                    return true;
                 }
             }
-            _ => {}
         }
+
         false
     }
 
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/ambiguity.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/ambiguity.rs
index 39f115ce0cd56..8a7dcb433dc02 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/ambiguity.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/ambiguity.rs
@@ -355,7 +355,8 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                         && self.tcx.trait_of_item(*item_id) == Some(*trait_id)
                         && let None = self.tainted_by_errors()
                     {
-                        let (verb, noun) = match self.tcx.associated_item(item_id).kind {
+                        let assoc_item = self.tcx.associated_item(item_id);
+                        let (verb, noun) = match assoc_item.kind {
                             ty::AssocKind::Const { .. } => ("refer to the", "constant"),
                             ty::AssocKind::Fn { .. } => ("call", "function"),
                             // This is already covered by E0223, but this following single match
@@ -374,17 +375,10 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                         );
                         err.code(E0790);
 
-                        if let Some(local_def_id) = data.trait_ref.def_id.as_local()
-                            && let hir::Node::Item(hir::Item {
-                                kind: hir::ItemKind::Trait(_, _, trait_ident, _, _, trait_item_refs),
-                                ..
-                            }) = self.tcx.hir_node_by_def_id(local_def_id)
-                            && let Some(method_ref) = trait_item_refs
-                                .iter()
-                                .find(|item_ref| item_ref.ident == *assoc_item_ident)
-                        {
+                        if item_id.is_local() {
+                            let trait_ident = self.tcx.item_name(*trait_id);
                             err.span_label(
-                                method_ref.span,
+                                self.tcx.def_span(*item_id),
                                 format!("`{trait_ident}::{assoc_item_ident}` defined here"),
                             );
                         }
diff --git a/compiler/rustc_trait_selection/src/traits/wf.rs b/compiler/rustc_trait_selection/src/traits/wf.rs
index d4e6a23f0eb6b..fed9f254cdf83 100644
--- a/compiler/rustc_trait_selection/src/traits/wf.rs
+++ b/compiler/rustc_trait_selection/src/traits/wf.rs
@@ -288,9 +288,9 @@ fn extend_cause_with_original_assoc_item_obligation<'tcx>(
             && let Some(&impl_item_id) =
                 tcx.impl_item_implementor_ids(impl_def_id).get(&projection_ty.def_id)
             && let Some(impl_item) =
-                items.iter().find(|item| item.id.owner_id.to_def_id() == impl_item_id)
+                items.iter().find(|item| item.owner_id.to_def_id() == impl_item_id)
         {
-            Some(tcx.hir_impl_item(impl_item.id).expect_type().span)
+            Some(tcx.hir_impl_item(*impl_item).expect_type().span)
         } else {
             None
         }
diff --git a/compiler/rustc_ty_utils/src/assoc.rs b/compiler/rustc_ty_utils/src/assoc.rs
index a65f9b347dc6d..648ced61e4df2 100644
--- a/compiler/rustc_ty_utils/src/assoc.rs
+++ b/compiler/rustc_ty_utils/src/assoc.rs
@@ -6,6 +6,8 @@ use rustc_hir::intravisit::{self, Visitor};
 use rustc_middle::query::Providers;
 use rustc_middle::ty::{self, ImplTraitInTraitData, TyCtxt};
 use rustc_middle::{bug, span_bug};
+use rustc_span::Ident;
+use rustc_span::symbol::kw;
 
 pub(crate) fn provide(providers: &mut Providers) {
     *providers = Providers {
@@ -28,15 +30,15 @@ fn associated_item_def_ids(tcx: TyCtxt<'_>, def_id: LocalDefId) -> &[DefId] {
             tcx.arena.alloc_from_iter(
                 trait_item_refs
                     .iter()
-                    .map(|trait_item_ref| trait_item_ref.id.owner_id.to_def_id())
+                    .map(|trait_item_ref| trait_item_ref.owner_id.to_def_id())
                     .chain(
                         trait_item_refs
                             .iter()
                             .filter(|trait_item_ref| {
-                                matches!(trait_item_ref.kind, hir::AssocItemKind::Fn { .. })
+                                matches!(tcx.def_kind(trait_item_ref.owner_id), DefKind::AssocFn)
                             })
                             .flat_map(|trait_item_ref| {
-                                let trait_fn_def_id = trait_item_ref.id.owner_id.def_id.to_def_id();
+                                let trait_fn_def_id = trait_item_ref.owner_id.to_def_id();
                                 tcx.associated_types_for_impl_traits_in_associated_fn(
                                     trait_fn_def_id,
                                 )
@@ -50,25 +52,23 @@ fn associated_item_def_ids(tcx: TyCtxt<'_>, def_id: LocalDefId) -> &[DefId] {
             // create a corresponding associated item using
             // associated_types_for_impl_traits_in_associated_fn query.
             tcx.arena.alloc_from_iter(
-                impl_
-                    .items
-                    .iter()
-                    .map(|impl_item_ref| impl_item_ref.id.owner_id.to_def_id())
-                    .chain(impl_.of_trait.iter().flat_map(|_| {
+                impl_.items.iter().map(|impl_item_ref| impl_item_ref.owner_id.to_def_id()).chain(
+                    impl_.of_trait.iter().flat_map(|_| {
                         impl_
                             .items
                             .iter()
                             .filter(|impl_item_ref| {
-                                matches!(impl_item_ref.kind, hir::AssocItemKind::Fn { .. })
+                                matches!(tcx.def_kind(impl_item_ref.owner_id), DefKind::AssocFn)
                             })
                             .flat_map(|impl_item_ref| {
-                                let impl_fn_def_id = impl_item_ref.id.owner_id.def_id.to_def_id();
+                                let impl_fn_def_id = impl_item_ref.owner_id.to_def_id();
                                 tcx.associated_types_for_impl_traits_in_associated_fn(
                                     impl_fn_def_id,
                                 )
                             })
                             .copied()
-                    })),
+                    }),
+                ),
             )
         }
         _ => span_bug!(item.span, "associated_item_def_ids: not impl or trait"),
@@ -92,46 +92,33 @@ fn impl_item_implementor_ids(tcx: TyCtxt<'_>, impl_id: DefId) -> DefIdMap<DefId>
 }
 
 fn associated_item(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::AssocItem {
-    let id = tcx.local_def_id_to_hir_id(def_id);
-    let parent_def_id = tcx.hir_get_parent_item(id);
-    let parent_item = tcx.hir_expect_item(parent_def_id.def_id);
-    match parent_item.kind {
-        hir::ItemKind::Impl(impl_) => {
-            if let Some(impl_item_ref) = impl_.items.iter().find(|i| i.id.owner_id.def_id == def_id)
-            {
-                let assoc_item = associated_item_from_impl_item_ref(impl_item_ref);
-                debug_assert_eq!(assoc_item.def_id.expect_local(), def_id);
-                return assoc_item;
-            }
-        }
-
-        hir::ItemKind::Trait(.., trait_item_refs) => {
-            if let Some(trait_item_ref) =
-                trait_item_refs.iter().find(|i| i.id.owner_id.def_id == def_id)
-            {
-                let assoc_item = associated_item_from_trait_item_ref(trait_item_ref);
-                debug_assert_eq!(assoc_item.def_id.expect_local(), def_id);
-                return assoc_item;
-            }
-        }
-
-        _ => {}
-    }
+    let assoc_item = match tcx.hir_node_by_def_id(def_id) {
+        hir::Node::TraitItem(ti) => associated_item_from_trait_item(tcx, ti),
+        hir::Node::ImplItem(ii) => associated_item_from_impl_item(tcx, ii),
+        node => span_bug!(tcx.def_span(def_id), "impl item or item not found: {:?}", node,),
+    };
+    debug_assert_eq!(assoc_item.def_id.expect_local(), def_id);
+    assoc_item
+}
 
-    span_bug!(
-        parent_item.span,
-        "unexpected parent of trait or impl item or item not found: {:?}",
-        parent_item.kind
-    )
+fn fn_has_self_parameter(tcx: TyCtxt<'_>, owner_id: hir::OwnerId) -> bool {
+    matches!(tcx.fn_arg_idents(owner_id.def_id), [Some(Ident { name: kw::SelfLower, .. }), ..])
 }
 
-fn associated_item_from_trait_item_ref(trait_item_ref: &hir::TraitItemRef) -> ty::AssocItem {
-    let owner_id = trait_item_ref.id.owner_id;
-    let name = trait_item_ref.ident.name;
-    let kind = match trait_item_ref.kind {
-        hir::AssocItemKind::Const => ty::AssocKind::Const { name },
-        hir::AssocItemKind::Fn { has_self } => ty::AssocKind::Fn { name, has_self },
-        hir::AssocItemKind::Type => ty::AssocKind::Type { data: ty::AssocTypeData::Normal(name) },
+fn associated_item_from_trait_item(
+    tcx: TyCtxt<'_>,
+    trait_item: &hir::TraitItem<'_>,
+) -> ty::AssocItem {
+    let owner_id = trait_item.owner_id;
+    let name = trait_item.ident.name;
+    let kind = match trait_item.kind {
+        hir::TraitItemKind::Const { .. } => ty::AssocKind::Const { name },
+        hir::TraitItemKind::Fn { .. } => {
+            ty::AssocKind::Fn { name, has_self: fn_has_self_parameter(tcx, owner_id) }
+        }
+        hir::TraitItemKind::Type { .. } => {
+            ty::AssocKind::Type { data: ty::AssocTypeData::Normal(name) }
+        }
     };
 
     ty::AssocItem {
@@ -142,22 +129,27 @@ fn associated_item_from_trait_item_ref(trait_item_ref: &hir::TraitItemRef) -> ty
     }
 }
 
-fn associated_item_from_impl_item_ref(impl_item_ref: &hir::ImplItemRef) -> ty::AssocItem {
-    let def_id = impl_item_ref.id.owner_id;
-    let name = impl_item_ref.ident.name;
-    let kind = match impl_item_ref.kind {
-        hir::AssocItemKind::Const => ty::AssocKind::Const { name },
-        hir::AssocItemKind::Fn { has_self } => ty::AssocKind::Fn { name, has_self },
-        hir::AssocItemKind::Type => ty::AssocKind::Type { data: ty::AssocTypeData::Normal(name) },
+fn associated_item_from_impl_item(tcx: TyCtxt<'_>, impl_item: &hir::ImplItem<'_>) -> ty::AssocItem {
+    let owner_id = impl_item.owner_id;
+    let name = impl_item.ident.name;
+    let kind = match impl_item.kind {
+        hir::ImplItemKind::Const { .. } => ty::AssocKind::Const { name },
+        hir::ImplItemKind::Fn { .. } => {
+            ty::AssocKind::Fn { name, has_self: fn_has_self_parameter(tcx, owner_id) }
+        }
+        hir::ImplItemKind::Type { .. } => {
+            ty::AssocKind::Type { data: ty::AssocTypeData::Normal(name) }
+        }
     };
 
     ty::AssocItem {
         kind,
-        def_id: def_id.to_def_id(),
-        trait_item_def_id: impl_item_ref.trait_item_def_id,
+        def_id: owner_id.to_def_id(),
+        trait_item_def_id: impl_item.trait_item_def_id,
         container: ty::AssocItemContainer::Impl,
     }
 }
+
 struct RPITVisitor<'tcx> {
     tcx: TyCtxt<'tcx>,
     synthetics: Vec<LocalDefId>,
diff --git a/src/librustdoc/clean/inline.rs b/src/librustdoc/clean/inline.rs
index 96199cb972a86..5cd6ab6b5e545 100644
--- a/src/librustdoc/clean/inline.rs
+++ b/src/librustdoc/clean/inline.rs
@@ -493,7 +493,7 @@ pub(crate) fn build_impl(
             impl_
                 .items
                 .iter()
-                .map(|item| tcx.hir_impl_item(item.id))
+                .map(|&item| tcx.hir_impl_item(item))
                 .filter(|item| {
                     // Filter out impl items whose corresponding trait item has `doc(hidden)`
                     // not to document such impl items.
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 5cd5c434521c0..8a16e9c37f320 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -2859,7 +2859,7 @@ fn clean_maybe_renamed_item<'tcx>(
             ItemKind::Trait(_, _, _, generics, bounds, item_ids) => {
                 let items = item_ids
                     .iter()
-                    .map(|ti| clean_trait_item(cx.tcx.hir_trait_item(ti.id), cx))
+                    .map(|&ti| clean_trait_item(cx.tcx.hir_trait_item(ti), cx))
                     .collect();
 
                 TraitItem(Box::new(Trait {
@@ -2902,7 +2902,7 @@ fn clean_impl<'tcx>(
     let items = impl_
         .items
         .iter()
-        .map(|ii| clean_impl_item(tcx.hir_impl_item(ii.id), cx))
+        .map(|&ii| clean_impl_item(tcx.hir_impl_item(ii), cx))
         .collect::<Vec<_>>();
 
     // If this impl block is an implementation of the Deref trait, then we
diff --git a/src/librustdoc/visit_ast.rs b/src/librustdoc/visit_ast.rs
index 2889bfae7b000..2f06d5dadc721 100644
--- a/src/librustdoc/visit_ast.rs
+++ b/src/librustdoc/visit_ast.rs
@@ -439,8 +439,8 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
 
         match item.kind {
             hir::ItemKind::ForeignMod { items, .. } => {
-                for item in items {
-                    let item = tcx.hir_foreign_item(item.id);
+                for &item in items {
+                    let item = tcx.hir_foreign_item(item);
                     self.visit_foreign_item_inner(item, None, None);
                 }
             }
diff --git a/src/tools/clippy/clippy_lints/src/arbitrary_source_item_ordering.rs b/src/tools/clippy/clippy_lints/src/arbitrary_source_item_ordering.rs
index b9ae9afe85100..3e41666c7026a 100644
--- a/src/tools/clippy/clippy_lints/src/arbitrary_source_item_ordering.rs
+++ b/src/tools/clippy/clippy_lints/src/arbitrary_source_item_ordering.rs
@@ -8,11 +8,13 @@ use clippy_utils::diagnostics::span_lint_and_note;
 use clippy_utils::is_cfg_test;
 use rustc_attr_data_structures::AttributeKind;
 use rustc_hir::{
-    AssocItemKind, Attribute, FieldDef, HirId, ImplItemRef, IsAuto, Item, ItemKind, Mod, QPath, TraitItemRef, TyKind,
+    Attribute, FieldDef, HirId, IsAuto, ImplItemId, Item, ItemKind, Mod, OwnerId, QPath, TraitItemId, TyKind,
     Variant, VariantData,
 };
+use rustc_middle::ty::AssocKind;
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_session::impl_lint_pass;
+use rustc_span::Ident;
 
 declare_clippy_lint! {
     /// ### What it does
@@ -194,22 +196,22 @@ impl ArbitrarySourceItemOrdering {
     }
 
     /// Produces a linting warning for incorrectly ordered impl items.
-    fn lint_impl_item<T: LintContext>(&self, cx: &T, item: &ImplItemRef, before_item: &ImplItemRef) {
+    fn lint_impl_item(&self, cx: &LateContext<'_>, item: ImplItemId, before_item: ImplItemId) {
         span_lint_and_note(
             cx,
             ARBITRARY_SOURCE_ITEM_ORDERING,
-            item.span,
+            cx.tcx.def_span(item.owner_id),
             format!(
                 "incorrect ordering of impl items (defined order: {:?})",
                 self.assoc_types_order
             ),
-            Some(before_item.span),
-            format!("should be placed before `{}`", before_item.ident.name),
+            Some(cx.tcx.def_span(before_item.owner_id)),
+            format!("should be placed before `{}`", cx.tcx.item_name(before_item.owner_id)),
         );
     }
 
     /// Produces a linting warning for incorrectly ordered item members.
-    fn lint_member_name<T: LintContext>(cx: &T, ident: &rustc_span::Ident, before_ident: &rustc_span::Ident) {
+    fn lint_member_name<T: LintContext>(cx: &T, ident: Ident, before_ident: Ident) {
         span_lint_and_note(
             cx,
             ARBITRARY_SOURCE_ITEM_ORDERING,
@@ -220,7 +222,7 @@ impl ArbitrarySourceItemOrdering {
         );
     }
 
-    fn lint_member_item<T: LintContext>(cx: &T, item: &Item<'_>, before_item: &Item<'_>, msg: &'static str) {
+    fn lint_member_item(cx: &LateContext<'_>, item: &Item<'_>, before_item: &Item<'_>, msg: &'static str) {
         let span = if let Some(ident) = item.kind.ident() {
             ident.span
         } else {
@@ -245,17 +247,17 @@ impl ArbitrarySourceItemOrdering {
     }
 
     /// Produces a linting warning for incorrectly ordered trait items.
-    fn lint_trait_item<T: LintContext>(&self, cx: &T, item: &TraitItemRef, before_item: &TraitItemRef) {
+    fn lint_trait_item(&self, cx: &LateContext<'_>, item: TraitItemId, before_item: TraitItemId) {
         span_lint_and_note(
             cx,
             ARBITRARY_SOURCE_ITEM_ORDERING,
-            item.span,
+            cx.tcx.def_span(item.owner_id),
             format!(
                 "incorrect ordering of trait items (defined order: {:?})",
                 self.assoc_types_order
             ),
-            Some(before_item.span),
-            format!("should be placed before `{}`", before_item.ident.name),
+            Some(cx.tcx.def_span(before_item.owner_id)),
+            format!("should be placed before `{}`", cx.tcx.item_name(before_item.owner_id)),
         );
     }
 }
@@ -283,7 +285,7 @@ impl<'tcx> LateLintPass<'tcx> for ArbitrarySourceItemOrdering {
                         && cur_v.ident.name.as_str() > variant.ident.name.as_str()
                         && cur_v.span != variant.span
                     {
-                        Self::lint_member_name(cx, &variant.ident, &cur_v.ident);
+                        Self::lint_member_name(cx, variant.ident, cur_v.ident);
                     }
                     cur_v = Some(variant);
                 }
@@ -299,7 +301,7 @@ impl<'tcx> LateLintPass<'tcx> for ArbitrarySourceItemOrdering {
                         && cur_f.ident.name.as_str() > field.ident.name.as_str()
                         && cur_f.span != field.span
                     {
-                        Self::lint_member_name(cx, &field.ident, &cur_f.ident);
+                        Self::lint_member_name(cx, field.ident, cur_f.ident);
                     }
                     cur_f = Some(field);
                 }
@@ -307,49 +309,53 @@ impl<'tcx> LateLintPass<'tcx> for ArbitrarySourceItemOrdering {
             ItemKind::Trait(is_auto, _safety, _ident, _generics, _generic_bounds, item_ref)
                 if self.enable_ordering_for_trait && *is_auto == IsAuto::No =>
             {
-                let mut cur_t: Option<&TraitItemRef> = None;
+                let mut cur_t: Option<(TraitItemId, Ident)> = None;
 
-                for item in *item_ref {
-                    if item.span.in_external_macro(cx.sess().source_map()) {
+                for &item in *item_ref {
+                    let span = cx.tcx.def_span(item.owner_id);
+                    let ident = cx.tcx.item_ident(item.owner_id);
+                    if span.in_external_macro(cx.sess().source_map()) {
                         continue;
                     }
 
-                    if let Some(cur_t) = cur_t {
-                        let cur_t_kind = convert_assoc_item_kind(cur_t.kind);
+                    if let Some((cur_t, cur_ident)) = cur_t {
+                        let cur_t_kind = convert_assoc_item_kind(cx, cur_t.owner_id);
                         let cur_t_kind_index = self.assoc_types_order.index_of(&cur_t_kind);
-                        let item_kind = convert_assoc_item_kind(item.kind);
+                        let item_kind = convert_assoc_item_kind(cx, item.owner_id);
                         let item_kind_index = self.assoc_types_order.index_of(&item_kind);
 
-                        if cur_t_kind == item_kind && cur_t.ident.name.as_str() > item.ident.name.as_str() {
-                            Self::lint_member_name(cx, &item.ident, &cur_t.ident);
+                        if cur_t_kind == item_kind && cur_ident.name.as_str() > ident.name.as_str() {
+                            Self::lint_member_name(cx, ident, cur_ident);
                         } else if cur_t_kind_index > item_kind_index {
                             self.lint_trait_item(cx, item, cur_t);
                         }
                     }
-                    cur_t = Some(item);
+                    cur_t = Some((item, ident));
                 }
             },
             ItemKind::Impl(trait_impl) if self.enable_ordering_for_impl => {
-                let mut cur_t: Option<&ImplItemRef> = None;
+                let mut cur_t: Option<(ImplItemId, Ident)> = None;
 
-                for item in trait_impl.items {
-                    if item.span.in_external_macro(cx.sess().source_map()) {
+                for &item in trait_impl.items {
+                    let span = cx.tcx.def_span(item.owner_id);
+                    let ident = cx.tcx.item_ident(item.owner_id);
+                    if span.in_external_macro(cx.sess().source_map()) {
                         continue;
                     }
 
-                    if let Some(cur_t) = cur_t {
-                        let cur_t_kind = convert_assoc_item_kind(cur_t.kind);
+                    if let Some((cur_t, cur_ident)) = cur_t {
+                        let cur_t_kind = convert_assoc_item_kind(cx, cur_t.owner_id);
                         let cur_t_kind_index = self.assoc_types_order.index_of(&cur_t_kind);
-                        let item_kind = convert_assoc_item_kind(item.kind);
+                        let item_kind = convert_assoc_item_kind(cx, item.owner_id);
                         let item_kind_index = self.assoc_types_order.index_of(&item_kind);
 
-                        if cur_t_kind == item_kind && cur_t.ident.name.as_str() > item.ident.name.as_str() {
-                            Self::lint_member_name(cx, &item.ident, &cur_t.ident);
+                        if cur_t_kind == item_kind && cur_ident.name.as_str() > ident.name.as_str() {
+                            Self::lint_member_name(cx, ident, cur_ident);
                         } else if cur_t_kind_index > item_kind_index {
                             self.lint_impl_item(cx, item, cur_t);
                         }
                     }
-                    cur_t = Some(item);
+                    cur_t = Some((item, ident));
                 }
             },
             _ => {}, // Catch-all for `ItemKinds` that don't have fields.
@@ -458,18 +464,19 @@ impl<'tcx> LateLintPass<'tcx> for ArbitrarySourceItemOrdering {
     }
 }
 
-/// Converts a [`rustc_hir::AssocItemKind`] to a
-/// [`SourceItemOrderingTraitAssocItemKind`].
+/// Converts a [`ty::AssocKind`] to a [`SourceItemOrderingTraitAssocItemKind`].
 ///
 /// This is implemented here because `rustc_hir` is not a dependency of
 /// `clippy_config`.
-fn convert_assoc_item_kind(value: AssocItemKind) -> SourceItemOrderingTraitAssocItemKind {
+fn convert_assoc_item_kind(cx: &LateContext<'_>, owner_id: OwnerId) -> SourceItemOrderingTraitAssocItemKind {
+    let kind = cx.tcx.associated_item(owner_id.def_id).kind;
+
     #[allow(clippy::enum_glob_use)] // Very local glob use for legibility.
     use SourceItemOrderingTraitAssocItemKind::*;
-    match value {
-        AssocItemKind::Const => Const,
-        AssocItemKind::Type => Type,
-        AssocItemKind::Fn { .. } => Fn,
+    match kind {
+        AssocKind::Const{..} => Const,
+        AssocKind::Type {..}=> Type,
+        AssocKind::Fn { .. } => Fn,
     }
 }
 
diff --git a/src/tools/clippy/clippy_lints/src/derivable_impls.rs b/src/tools/clippy/clippy_lints/src/derivable_impls.rs
index 10331b3855b84..0a481ddcd12e4 100644
--- a/src/tools/clippy/clippy_lints/src/derivable_impls.rs
+++ b/src/tools/clippy/clippy_lints/src/derivable_impls.rs
@@ -192,7 +192,7 @@ impl<'tcx> LateLintPass<'tcx> for DerivableImpls {
             && !item.span.from_expansion()
             && let Some(def_id) = trait_ref.trait_def_id()
             && cx.tcx.is_diagnostic_item(sym::Default, def_id)
-            && let impl_item_hir = child.id.hir_id()
+            && let impl_item_hir = child.hir_id()
             && let Node::ImplItem(impl_item) = cx.tcx.hir_node(impl_item_hir)
             && let ImplItemKind::Fn(_, b) = &impl_item.kind
             && let Body { value: func_expr, .. } = cx.tcx.hir_body(*b)
diff --git a/src/tools/clippy/clippy_lints/src/empty_drop.rs b/src/tools/clippy/clippy_lints/src/empty_drop.rs
index d557a36c7ac2d..4e948701da4ff 100644
--- a/src/tools/clippy/clippy_lints/src/empty_drop.rs
+++ b/src/tools/clippy/clippy_lints/src/empty_drop.rs
@@ -41,7 +41,7 @@ impl LateLintPass<'_> for EmptyDrop {
             ..
         }) = item.kind
             && trait_ref.trait_def_id() == cx.tcx.lang_items().drop_trait()
-            && let impl_item_hir = child.id.hir_id()
+            && let impl_item_hir = child.hir_id()
             && let Node::ImplItem(impl_item) = cx.tcx.hir_node(impl_item_hir)
             && let ImplItemKind::Fn(_, b) = &impl_item.kind
             && let Body { value: func_expr, .. } = cx.tcx.hir_body(*b)
diff --git a/src/tools/clippy/clippy_lints/src/escape.rs b/src/tools/clippy/clippy_lints/src/escape.rs
index 2cb3b32babe89..db2fea1aae95d 100644
--- a/src/tools/clippy/clippy_lints/src/escape.rs
+++ b/src/tools/clippy/clippy_lints/src/escape.rs
@@ -1,7 +1,8 @@
 use clippy_config::Conf;
 use clippy_utils::diagnostics::span_lint_hir;
 use rustc_abi::ExternAbi;
-use rustc_hir::{AssocItemKind, Body, FnDecl, HirId, HirIdSet, Impl, ItemKind, Node, Pat, PatKind, intravisit};
+use rustc_hir::{Body, FnDecl, HirId, HirIdSet, Node, Pat, PatKind, intravisit};
+use rustc_hir::def::DefKind;
 use rustc_hir_typeck::expr_use_visitor::{Delegate, ExprUseVisitor, PlaceBase, PlaceWithHirId};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::mir::FakeReadCause;
@@ -84,23 +85,18 @@ impl<'tcx> LateLintPass<'tcx> for BoxedLocal {
             .def_id;
 
         let mut trait_self_ty = None;
-        if let Node::Item(item) = cx.tcx.hir_node_by_def_id(parent_id) {
+        match cx.tcx.def_kind(parent_id) {
             // If the method is an impl for a trait, don't warn.
-            if let ItemKind::Impl(Impl { of_trait: Some(_), .. }) = item.kind {
-                return;
+            DefKind::Impl { of_trait: true } => {
+                return
             }
 
             // find `self` ty for this trait if relevant
-            if let ItemKind::Trait(_, _, _, _, _, items) = item.kind {
-                for trait_item in items {
-                    if trait_item.id.owner_id.def_id == fn_def_id
-                        // be sure we have `self` parameter in this function
-                        && trait_item.kind == (AssocItemKind::Fn { has_self: true })
-                    {
-                        trait_self_ty = Some(TraitRef::identity(cx.tcx, trait_item.id.owner_id.to_def_id()).self_ty());
-                    }
-                }
+            DefKind::Trait => {
+                trait_self_ty = Some(TraitRef::identity(cx.tcx, parent_id.to_def_id()).self_ty());
             }
+
+            _ => {}
         }
 
         let mut v = EscapeDelegate {
diff --git a/src/tools/clippy/clippy_lints/src/fallible_impl_from.rs b/src/tools/clippy/clippy_lints/src/fallible_impl_from.rs
index 68d0cd19c8a69..552cd721f4ef9 100644
--- a/src/tools/clippy/clippy_lints/src/fallible_impl_from.rs
+++ b/src/tools/clippy/clippy_lints/src/fallible_impl_from.rs
@@ -52,20 +52,20 @@ declare_lint_pass!(FallibleImplFrom => [FALLIBLE_IMPL_FROM]);
 impl<'tcx> LateLintPass<'tcx> for FallibleImplFrom {
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
         // check for `impl From<???> for ..`
-        if let hir::ItemKind::Impl(impl_) = &item.kind
+        if let hir::ItemKind::Impl(_) = &item.kind
             && let Some(impl_trait_ref) = cx.tcx.impl_trait_ref(item.owner_id)
             && cx
                 .tcx
                 .is_diagnostic_item(sym::From, impl_trait_ref.skip_binder().def_id)
         {
-            lint_impl_body(cx, item.span, impl_.items);
+            lint_impl_body(cx, item.owner_id, item.span);
         }
     }
 }
 
-fn lint_impl_body(cx: &LateContext<'_>, impl_span: Span, impl_items: &[hir::ImplItemRef]) {
+fn lint_impl_body(cx: &LateContext<'_>, item_def_id: hir::OwnerId, impl_span: Span) {
     use rustc_hir::intravisit::{self, Visitor};
-    use rustc_hir::{Expr, ImplItemKind};
+    use rustc_hir::Expr;
 
     struct FindPanicUnwrap<'a, 'tcx> {
         lcx: &'a LateContext<'tcx>,
@@ -96,35 +96,35 @@ fn lint_impl_body(cx: &LateContext<'_>, impl_span: Span, impl_items: &[hir::Impl
         }
     }
 
-    for impl_item in impl_items {
-        if impl_item.ident.name == sym::from
-            && let ImplItemKind::Fn(_, body_id) = cx.tcx.hir_impl_item(impl_item.id).kind
-        {
-            // check the body for `begin_panic` or `unwrap`
-            let body = cx.tcx.hir_body(body_id);
-            let mut fpu = FindPanicUnwrap {
-                lcx: cx,
-                typeck_results: cx.tcx.typeck(impl_item.id.owner_id.def_id),
-                result: Vec::new(),
-            };
-            fpu.visit_expr(body.value);
+    for impl_item in cx.tcx.associated_items(item_def_id)
+        .filter_by_name_unhygienic_and_kind(sym::from, ty::AssocTag::Fn)
+    {
+        let impl_item_def_id= impl_item.def_id.expect_local();
 
-            // if we've found one, lint
-            if !fpu.result.is_empty() {
-                span_lint_and_then(
-                    cx,
-                    FALLIBLE_IMPL_FROM,
-                    impl_span,
-                    "consider implementing `TryFrom` instead",
-                    move |diag| {
-                        diag.help(
-                            "`From` is intended for infallible conversions only. \
-                            Use `TryFrom` if there's a possibility for the conversion to fail",
-                        );
-                        diag.span_note(fpu.result, "potential failure(s)");
-                    },
-                );
-            }
+        // check the body for `begin_panic` or `unwrap`
+        let body = cx.tcx.hir_body_owned_by(impl_item_def_id);
+        let mut fpu = FindPanicUnwrap {
+            lcx: cx,
+            typeck_results: cx.tcx.typeck(impl_item_def_id),
+            result: Vec::new(),
+        };
+        fpu.visit_expr(body.value);
+
+        // if we've found one, lint
+        if !fpu.result.is_empty() {
+            span_lint_and_then(
+                cx,
+                FALLIBLE_IMPL_FROM,
+                impl_span,
+                "consider implementing `TryFrom` instead",
+                move |diag| {
+                    diag.help(
+                        "`From` is intended for infallible conversions only. \
+                        Use `TryFrom` if there's a possibility for the conversion to fail",
+                    );
+                    diag.span_note(fpu.result, "potential failure(s)");
+                },
+            );
         }
     }
 }
diff --git a/src/tools/clippy/clippy_lints/src/from_over_into.rs b/src/tools/clippy/clippy_lints/src/from_over_into.rs
index be887b03ae4b6..85b40ba7419b3 100644
--- a/src/tools/clippy/clippy_lints/src/from_over_into.rs
+++ b/src/tools/clippy/clippy_lints/src/from_over_into.rs
@@ -9,7 +9,7 @@ use clippy_utils::source::SpanRangeExt;
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::{Visitor, walk_path};
 use rustc_hir::{
-    FnRetTy, GenericArg, GenericArgs, HirId, Impl, ImplItemKind, ImplItemRef, Item, ItemKind, PatKind, Path,
+    FnRetTy, GenericArg, GenericArgs, HirId, Impl, ImplItemKind, ImplItemId, Item, ItemKind, PatKind, Path,
     PathSegment, Ty, TyKind,
 };
 use rustc_lint::{LateContext, LateLintPass};
@@ -102,7 +102,7 @@ impl<'tcx> LateLintPass<'tcx> for FromOverInto {
                         middle_trait_ref.self_ty()
                     );
                     if let Some(suggestions) =
-                        convert_to_from(cx, into_trait_seg, target_ty.as_unambig_ty(), self_ty, impl_item_ref)
+                        convert_to_from(cx, into_trait_seg, target_ty.as_unambig_ty(), self_ty, *impl_item_ref)
                     {
                         diag.multipart_suggestion(message, suggestions, Applicability::MachineApplicable);
                     } else {
@@ -164,14 +164,14 @@ fn convert_to_from(
     into_trait_seg: &PathSegment<'_>,
     target_ty: &Ty<'_>,
     self_ty: &Ty<'_>,
-    impl_item_ref: &ImplItemRef,
+    impl_item_ref: ImplItemId,
 ) -> Option<Vec<(Span, String)>> {
     if !target_ty.find_self_aliases().is_empty() {
         // It's tricky to expand self-aliases correctly, we'll ignore it to not cause a
         // bad suggestion/fix.
         return None;
     }
-    let impl_item = cx.tcx.hir_impl_item(impl_item_ref.id);
+    let impl_item = cx.tcx.hir_impl_item(impl_item_ref);
     let ImplItemKind::Fn(ref sig, body_id) = impl_item.kind else {
         return None;
     };
diff --git a/src/tools/clippy/clippy_lints/src/functions/renamed_function_params.rs b/src/tools/clippy/clippy_lints/src/functions/renamed_function_params.rs
index 2d22bb157a93c..0d6191f2c9715 100644
--- a/src/tools/clippy/clippy_lints/src/functions/renamed_function_params.rs
+++ b/src/tools/clippy/clippy_lints/src/functions/renamed_function_params.rs
@@ -2,7 +2,7 @@ use clippy_utils::diagnostics::span_lint_and_then;
 use rustc_errors::{Applicability, MultiSpan};
 use rustc_hir::def_id::{DefId, DefIdSet};
 use rustc_hir::hir_id::OwnerId;
-use rustc_hir::{Impl, ImplItem, ImplItemKind, ImplItemRef, ItemKind, Node, TraitRef};
+use rustc_hir::{Impl, ImplItem, ImplItemKind, ItemKind, Node, TraitRef};
 use rustc_lint::LateContext;
 use rustc_span::Span;
 use rustc_span::symbol::{Ident, kw};
@@ -15,11 +15,10 @@ pub(super) fn check_impl_item(cx: &LateContext<'_>, item: &ImplItem<'_>, ignored
         && let parent_node = cx.tcx.parent_hir_node(item.hir_id())
         && let Node::Item(parent_item) = parent_node
         && let ItemKind::Impl(Impl {
-            items,
             of_trait: Some(trait_ref),
             ..
         }) = &parent_item.kind
-        && let Some(did) = trait_item_def_id_of_impl(items, item.owner_id)
+        && let Some(did) = trait_item_def_id_of_impl(cx, item.owner_id)
         && !is_from_ignored_trait(trait_ref, ignored_traits)
     {
         let mut param_idents_iter = cx.tcx.hir_body_param_idents(body_id);
@@ -93,14 +92,8 @@ impl RenamedFnArgs {
 }
 
 /// Get the [`trait_item_def_id`](ImplItemRef::trait_item_def_id) of a relevant impl item.
-fn trait_item_def_id_of_impl(items: &[ImplItemRef], target: OwnerId) -> Option<DefId> {
-    items.iter().find_map(|item| {
-        if item.id.owner_id == target {
-            item.trait_item_def_id
-        } else {
-            None
-        }
-    })
+fn trait_item_def_id_of_impl(cx: &LateContext<'_>, target: OwnerId) -> Option<DefId> {
+    cx.tcx.associated_item(target).trait_item_def_id
 }
 
 fn is_from_ignored_trait(of_trait: &TraitRef<'_>, ignored_traits: &DefIdSet) -> bool {
diff --git a/src/tools/clippy/clippy_lints/src/implicit_hasher.rs b/src/tools/clippy/clippy_lints/src/implicit_hasher.rs
index cab7a9fb70990..b3c90f364e834 100644
--- a/src/tools/clippy/clippy_lints/src/implicit_hasher.rs
+++ b/src/tools/clippy/clippy_lints/src/implicit_hasher.rs
@@ -130,7 +130,7 @@ impl<'tcx> LateLintPass<'tcx> for ImplicitHasher {
                     });
 
                     let mut ctr_vis = ImplicitHasherConstructorVisitor::new(cx, target);
-                    for item in impl_.items.iter().map(|item| cx.tcx.hir_impl_item(item.id)) {
+                    for item in impl_.items.iter().map(|&item| cx.tcx.hir_impl_item(item)) {
                         ctr_vis.visit_impl_item(item);
                     }
 
diff --git a/src/tools/clippy/clippy_lints/src/infallible_try_from.rs b/src/tools/clippy/clippy_lints/src/infallible_try_from.rs
index b54c289fa7e13..e79fcec6e6acf 100644
--- a/src/tools/clippy/clippy_lints/src/infallible_try_from.rs
+++ b/src/tools/clippy/clippy_lints/src/infallible_try_from.rs
@@ -1,8 +1,9 @@
 use clippy_utils::diagnostics::span_lint;
 use clippy_utils::sym;
 use rustc_errors::MultiSpan;
-use rustc_hir::{AssocItemKind, Item, ItemKind};
+use rustc_hir::{Item, ItemKind};
 use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::AssocTag;
 use rustc_session::declare_lint_pass;
 
 declare_clippy_lint! {
@@ -51,25 +52,23 @@ impl<'tcx> LateLintPass<'tcx> for InfallibleTryFrom {
         if !cx.tcx.is_diagnostic_item(sym::TryFrom, trait_def_id) {
             return;
         }
-        for ii in imp.items {
-            if ii.kind == AssocItemKind::Type {
-                let ii = cx.tcx.hir_impl_item(ii.id);
-                if ii.ident.name != sym::Error {
-                    continue;
-                }
-                let ii_ty = ii.expect_type();
-                let ii_ty_span = ii_ty.span;
-                let ii_ty = clippy_utils::ty::ty_from_hir_ty(cx, ii_ty);
-                if !ii_ty.is_inhabited_from(cx.tcx, ii.owner_id.to_def_id(), cx.typing_env()) {
-                    let mut span = MultiSpan::from_span(cx.tcx.def_span(item.owner_id.to_def_id()));
-                    span.push_span_label(ii_ty_span, "infallible error type");
-                    span_lint(
-                        cx,
-                        INFALLIBLE_TRY_FROM,
-                        span,
-                        "infallible TryFrom impl; consider implementing From, instead",
-                    );
-                }
+        for ii in cx.tcx.associated_items(item.owner_id.def_id)
+            .filter_by_name_unhygienic_and_kind(sym::Error, AssocTag::Type)
+        {
+            let ii_ty = cx.tcx.type_of(ii.def_id).instantiate_identity();
+            if !ii_ty.is_inhabited_from(cx.tcx, ii.def_id, cx.typing_env()) {
+                let mut span = MultiSpan::from_span(cx.tcx.def_span(item.owner_id.to_def_id()));
+                let ii_ty_span = cx.tcx.hir_node_by_def_id(ii.def_id.expect_local())
+                    .expect_impl_item()
+                    .expect_type()
+                    .span;
+                span.push_span_label(ii_ty_span, "infallible error type");
+                span_lint(
+                    cx,
+                    INFALLIBLE_TRY_FROM,
+                    span,
+                    "infallible TryFrom impl; consider implementing From, instead",
+                );
             }
         }
     }
diff --git a/src/tools/clippy/clippy_lints/src/iter_without_into_iter.rs b/src/tools/clippy/clippy_lints/src/iter_without_into_iter.rs
index 900b20aa9cfb7..03038f0ab49c9 100644
--- a/src/tools/clippy/clippy_lints/src/iter_without_into_iter.rs
+++ b/src/tools/clippy/clippy_lints/src/iter_without_into_iter.rs
@@ -139,13 +139,12 @@ impl LateLintPass<'_> for IterWithoutIntoIter {
                 // We can't check inherent impls for slices, but we know that they have an `iter(_mut)` method
                 ty.peel_refs().is_slice() || get_adt_inherent_method(cx, ty, expected_method_name).is_some()
             })
-            && let Some(iter_assoc_span) = imp.items.iter().find_map(|item| {
-                if item.ident.name == sym::IntoIter {
-                    Some(cx.tcx.hir_impl_item(item.id).expect_type().span)
-                } else {
-                    None
-                }
-            })
+            && let Some(iter_assoc_span) = cx.tcx.associated_items(item.owner_id)
+                .filter_by_name_unhygienic_and_kind(sym::IntoIter, ty::AssocTag::Type)
+                .next()
+                .map(|assoc_item| {
+                    cx.tcx.hir_node_by_def_id(assoc_item.def_id.expect_local()).expect_impl_item().expect_type().span
+                })
             && is_ty_exported(cx, ty)
         {
             span_lint_and_then(
diff --git a/src/tools/clippy/clippy_lints/src/len_zero.rs b/src/tools/clippy/clippy_lints/src/len_zero.rs
index aded31971cec0..d32017a8b4144 100644
--- a/src/tools/clippy/clippy_lints/src/len_zero.rs
+++ b/src/tools/clippy/clippy_lints/src/len_zero.rs
@@ -10,14 +10,15 @@ use rustc_errors::Applicability;
 use rustc_hir::def::Res;
 use rustc_hir::def_id::{DefId, DefIdSet};
 use rustc_hir::{
-    AssocItemKind, BinOpKind, Expr, ExprKind, FnRetTy, GenericArg, GenericBound, HirId, ImplItem, ImplItemKind,
+    BinOpKind, Expr, ExprKind, FnRetTy, GenericArg, GenericBound, HirId, ImplItem, ImplItemKind,
     ImplicitSelfKind, Item, ItemKind, Mutability, Node, OpaqueTyOrigin, PatExprKind, PatKind, PathSegment, PrimTy,
-    QPath, TraitItemRef, TyKind,
+    QPath, TraitItemId, TyKind,
 };
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::{self, FnSig, Ty};
 use rustc_session::declare_lint_pass;
 use rustc_span::source_map::Spanned;
+use rustc_span::symbol::kw;
 use rustc_span::{Ident, Span, Symbol};
 use rustc_trait_selection::traits::supertrait_def_ids;
 
@@ -264,22 +265,13 @@ fn span_without_enclosing_paren(cx: &LateContext<'_>, span: Span) -> Span {
     }
 }
 
-fn check_trait_items(cx: &LateContext<'_>, visited_trait: &Item<'_>, ident: Ident, trait_items: &[TraitItemRef]) {
-    fn is_named_self(cx: &LateContext<'_>, item: &TraitItemRef, name: Symbol) -> bool {
-        item.ident.name == name
-            && if let AssocItemKind::Fn { has_self } = item.kind {
-                has_self && {
-                    cx.tcx
-                        .fn_sig(item.id.owner_id)
-                        .skip_binder()
-                        .inputs()
-                        .skip_binder()
-                        .len()
-                        == 1
-                }
-            } else {
-                false
-            }
+fn check_trait_items(cx: &LateContext<'_>, visited_trait: &Item<'_>, ident: Ident, trait_items: &[TraitItemId]) {
+    fn is_named_self(cx: &LateContext<'_>, item: &TraitItemId, name: Symbol) -> bool {
+        cx.tcx.item_name(item.owner_id) == name
+            && matches!(
+                cx.tcx.fn_arg_idents(item.owner_id),
+                [Some(Ident { name: kw::SelfLower, .. })],
+            )
     }
 
     // fill the set with current and super traits
diff --git a/src/tools/clippy/clippy_lints/src/lifetimes.rs b/src/tools/clippy/clippy_lints/src/lifetimes.rs
index 8fe0c9d60f961..e308577e7f87f 100644
--- a/src/tools/clippy/clippy_lints/src/lifetimes.rs
+++ b/src/tools/clippy/clippy_lints/src/lifetimes.rs
@@ -716,7 +716,7 @@ fn report_extra_impl_lifetimes<'tcx>(cx: &LateContext<'tcx>, impl_: &'tcx Impl<'
         walk_trait_ref(&mut checker, trait_ref);
     }
     walk_unambig_ty(&mut checker, impl_.self_ty);
-    for item in impl_.items {
+    for &item in impl_.items {
         walk_impl_item_ref(&mut checker, item);
     }
 
diff --git a/src/tools/clippy/clippy_lints/src/missing_fields_in_debug.rs b/src/tools/clippy/clippy_lints/src/missing_fields_in_debug.rs
index d4d33029dbdb1..760ecf0758921 100644
--- a/src/tools/clippy/clippy_lints/src/missing_fields_in_debug.rs
+++ b/src/tools/clippy/clippy_lints/src/missing_fields_in_debug.rs
@@ -8,7 +8,7 @@ use rustc_ast::LitKind;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::{
-    Block, Expr, ExprKind, Impl, ImplItem, ImplItemKind, Item, ItemKind, LangItem, Node, QPath, TyKind, VariantData,
+    Block, Expr, ExprKind, Impl, Item, ItemKind, LangItem, Node, QPath, TyKind, VariantData,
 };
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::{Ty, TypeckResults};
@@ -200,7 +200,7 @@ fn check_struct<'tcx>(
 impl<'tcx> LateLintPass<'tcx> for MissingFieldsInDebug {
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
         // is this an `impl Debug for X` block?
-        if let ItemKind::Impl(Impl { of_trait: Some(trait_ref), self_ty, items, .. }) = item.kind
+        if let ItemKind::Impl(Impl { of_trait: Some(trait_ref), self_ty, .. }) = item.kind
             && let Res::Def(DefKind::Trait, trait_def_id) = trait_ref.path.res
             && let TyKind::Path(QPath::Resolved(_, self_path)) = &self_ty.kind
             // make sure that the self type is either a struct, an enum or a union
@@ -212,9 +212,8 @@ impl<'tcx> LateLintPass<'tcx> for MissingFieldsInDebug {
             && !cx.tcx.is_automatically_derived(item.owner_id.to_def_id())
             && !item.span.from_expansion()
             // find `Debug::fmt` function
-            && let Some(fmt_item) = items.iter().find(|i| i.ident.name == sym::fmt)
-            && let ImplItem { kind: ImplItemKind::Fn(_, body_id), .. } = cx.tcx.hir_impl_item(fmt_item.id)
-            && let body = cx.tcx.hir_body(*body_id)
+            && let Some(fmt_item) = cx.tcx.associated_items(item.owner_id).filter_by_name_unhygienic(sym::fmt).next()
+            && let body = cx.tcx.hir_body_owned_by(fmt_item.def_id.expect_local())
             && let ExprKind::Block(block, _) = body.value.kind
             // inspect `self`
             && let self_ty = cx.tcx.type_of(self_path_did).skip_binder().peel_refs()
@@ -222,7 +221,7 @@ impl<'tcx> LateLintPass<'tcx> for MissingFieldsInDebug {
             && let Some(self_def_id) = self_adt.did().as_local()
             && let Node::Item(self_item) = cx.tcx.hir_node_by_def_id(self_def_id)
             // NB: can't call cx.typeck_results() as we are not in a body
-            && let typeck_results = cx.tcx.typeck_body(*body_id)
+            && let typeck_results = cx.tcx.typeck_body(body.id())
             && should_lint(cx, typeck_results, block)
             // we intentionally only lint structs, see lint description
             && let ItemKind::Struct(_, _, data) = &self_item.kind
diff --git a/src/tools/clippy/clippy_lints/src/missing_inline.rs b/src/tools/clippy/clippy_lints/src/missing_inline.rs
index 25c95d2343633..329f719343756 100644
--- a/src/tools/clippy/clippy_lints/src/missing_inline.rs
+++ b/src/tools/clippy/clippy_lints/src/missing_inline.rs
@@ -104,16 +104,16 @@ impl<'tcx> LateLintPass<'tcx> for MissingInline {
             hir::ItemKind::Trait(ref _is_auto, ref _unsafe, _ident, _generics, _bounds, trait_items) => {
                 // note: we need to check if the trait is exported so we can't use
                 // `LateLintPass::check_trait_item` here.
-                for tit in trait_items {
-                    let tit_ = cx.tcx.hir_trait_item(tit.id);
+                for &tit in trait_items {
+                    let tit_ = cx.tcx.hir_trait_item(tit);
                     match tit_.kind {
                         hir::TraitItemKind::Const(..) | hir::TraitItemKind::Type(..) => {},
                         hir::TraitItemKind::Fn(..) => {
-                            if cx.tcx.defaultness(tit.id.owner_id).has_value() {
+                            if cx.tcx.defaultness(tit.owner_id).has_value() {
                                 // trait method with default body needs inline in case
                                 // an impl is not provided
                                 let desc = "a default trait method";
-                                let item = cx.tcx.hir_trait_item(tit.id);
+                                let item = cx.tcx.hir_trait_item(tit);
                                 let attrs = cx.tcx.hir_attrs(item.hir_id());
                                 check_missing_inline_attrs(cx, attrs, item.span, desc);
                             }
diff --git a/src/tools/clippy/clippy_lints/src/missing_trait_methods.rs b/src/tools/clippy/clippy_lints/src/missing_trait_methods.rs
index e266c36b6e734..fa61d0fa11afc 100644
--- a/src/tools/clippy/clippy_lints/src/missing_trait_methods.rs
+++ b/src/tools/clippy/clippy_lints/src/missing_trait_methods.rs
@@ -61,15 +61,14 @@ impl<'tcx> LateLintPass<'tcx> for MissingTraitMethods {
         if !is_lint_allowed(cx, MISSING_TRAIT_METHODS, item.hir_id())
             && span_is_local(item.span)
             && let ItemKind::Impl(Impl {
-                items,
                 of_trait: Some(trait_ref),
                 ..
             }) = item.kind
             && let Some(trait_id) = trait_ref.trait_def_id()
         {
-            let trait_item_ids: DefIdSet = items
-                .iter()
-                .filter_map(|impl_item| impl_item.trait_item_def_id)
+            let trait_item_ids: DefIdSet = cx.tcx.associated_items(item.owner_id)
+                .in_definition_order()
+                .filter_map(|assoc_item| assoc_item.trait_item_def_id)
                 .collect();
 
             for assoc in cx
diff --git a/src/tools/clippy/clippy_lints/src/new_without_default.rs b/src/tools/clippy/clippy_lints/src/new_without_default.rs
index 4b73a4455f55b..3b86f1d1f593c 100644
--- a/src/tools/clippy/clippy_lints/src/new_without_default.rs
+++ b/src/tools/clippy/clippy_lints/src/new_without_default.rs
@@ -6,6 +6,7 @@ use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_hir::HirIdSet;
 use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_middle::ty::AssocKind;
 use rustc_session::impl_lint_pass;
 use rustc_span::sym;
 
@@ -61,18 +62,18 @@ impl<'tcx> LateLintPass<'tcx> for NewWithoutDefault {
             of_trait: None,
             generics,
             self_ty: impl_self_ty,
-            items,
             ..
         }) = item.kind
         {
-            for assoc_item in *items {
-                if assoc_item.kind == (hir::AssocItemKind::Fn { has_self: false }) {
-                    let impl_item = cx.tcx.hir_impl_item(assoc_item.id);
+            for assoc_item in cx.tcx.associated_items(item.owner_id.def_id)
+                .filter_by_name_unhygienic(sym::new)
+            {
+                if let AssocKind::Fn { has_self: false, .. } = assoc_item.kind {
+                    let impl_item = cx.tcx.hir_node_by_def_id(assoc_item.def_id.expect_local()).expect_impl_item();
                     if impl_item.span.in_external_macro(cx.sess().source_map()) {
                         return;
                     }
                     if let hir::ImplItemKind::Fn(ref sig, _) = impl_item.kind {
-                        let name = impl_item.ident.name;
                         let id = impl_item.owner_id;
                         if sig.header.is_unsafe() {
                             // can't be implemented for unsafe new
@@ -88,11 +89,9 @@ impl<'tcx> LateLintPass<'tcx> for NewWithoutDefault {
                             return;
                         }
                         if sig.decl.inputs.is_empty()
-                            && name == sym::new
                             && cx.effective_visibilities.is_reachable(impl_item.owner_id.def_id)
-                            && let self_def_id = cx.tcx.hir_get_parent_item(id.into())
-                            && let self_ty = cx.tcx.type_of(self_def_id).instantiate_identity()
-                            && self_ty == return_ty(cx, id)
+                            && let self_ty = cx.tcx.type_of(item.owner_id).instantiate_identity()
+                            && self_ty == return_ty(cx, impl_item.owner_id)
                             && let Some(default_trait_id) = cx.tcx.get_diagnostic_item(sym::Default)
                         {
                             if self.impling_types.is_none() {
@@ -111,7 +110,7 @@ impl<'tcx> LateLintPass<'tcx> for NewWithoutDefault {
                             // Check if a Default implementation exists for the Self type, regardless of
                             // generics
                             if let Some(ref impling_types) = self.impling_types
-                                && let self_def = cx.tcx.type_of(self_def_id).instantiate_identity()
+                                && let self_def = cx.tcx.type_of(item.owner_id).instantiate_identity()
                                 && let Some(self_def) = self_def.ty_adt_def()
                                 && let Some(self_local_did) = self_def.did().as_local()
                                 && let self_id = cx.tcx.local_def_id_to_hir_id(self_local_did)
diff --git a/src/tools/clippy/clippy_lints/src/partialeq_ne_impl.rs b/src/tools/clippy/clippy_lints/src/partialeq_ne_impl.rs
index 8eaf65e63065e..301b2cd4bf2fc 100644
--- a/src/tools/clippy/clippy_lints/src/partialeq_ne_impl.rs
+++ b/src/tools/clippy/clippy_lints/src/partialeq_ne_impl.rs
@@ -43,12 +43,12 @@ impl<'tcx> LateLintPass<'tcx> for PartialEqNeImpl {
             && trait_ref.path.res.def_id() == eq_trait
         {
             for impl_item in *impl_items {
-                if impl_item.ident.name == sym::ne {
+                if cx.tcx.item_name(impl_item.owner_id) == sym::ne {
                     span_lint_hir(
                         cx,
                         PARTIALEQ_NE_IMPL,
-                        impl_item.id.hir_id(),
-                        impl_item.span,
+                        impl_item.hir_id(),
+                        cx.tcx.def_span(impl_item.owner_id),
                         "re-implementing `PartialEq::ne` is unnecessary",
                     );
                 }
diff --git a/src/tools/clippy/clippy_lints/src/same_name_method.rs b/src/tools/clippy/clippy_lints/src/same_name_method.rs
index 226e8ff6adbf5..85fde780e6819 100644
--- a/src/tools/clippy/clippy_lints/src/same_name_method.rs
+++ b/src/tools/clippy/clippy_lints/src/same_name_method.rs
@@ -3,7 +3,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::{HirId, Impl, ItemKind, Node, Path, QPath, TraitRef, TyKind};
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty::AssocItem;
+use rustc_middle::ty::{AssocKind, AssocItem};
 use rustc_session::declare_lint_pass;
 use rustc_span::Span;
 use rustc_span::symbol::Symbol;
@@ -54,7 +54,6 @@ impl<'tcx> LateLintPass<'tcx> for SameNameMethod {
             if matches!(cx.tcx.def_kind(id.owner_id), DefKind::Impl { .. })
                 && let item = cx.tcx.hir_item(id)
                 && let ItemKind::Impl(Impl {
-                    items,
                     of_trait,
                     self_ty,
                     ..
@@ -115,13 +114,11 @@ impl<'tcx> LateLintPass<'tcx> for SameNameMethod {
                             }
                         };
 
-                        for impl_item_ref in (*items)
-                            .iter()
-                            .filter(|impl_item_ref| matches!(impl_item_ref.kind, rustc_hir::AssocItemKind::Fn { .. }))
-                        {
-                            let method_name = impl_item_ref.ident.name;
-                            methods_in_trait.remove(&method_name);
-                            check_trait_method(method_name, impl_item_ref.span);
+                        for assoc_item in cx.tcx.associated_items(id.owner_id).in_definition_order() {
+                            if let AssocKind::Fn { name, .. } = assoc_item.kind {
+                                methods_in_trait.remove(&name);
+                                check_trait_method(name, cx.tcx.def_span(assoc_item.def_id));
+                            }
                         }
 
                         for method_name in methods_in_trait {
@@ -129,14 +126,11 @@ impl<'tcx> LateLintPass<'tcx> for SameNameMethod {
                         }
                     },
                     None => {
-                        for impl_item_ref in (*items)
-                            .iter()
-                            .filter(|impl_item_ref| matches!(impl_item_ref.kind, rustc_hir::AssocItemKind::Fn { .. }))
-                        {
-                            let method_name = impl_item_ref.ident.name;
-                            let impl_span = impl_item_ref.span;
-                            let hir_id = impl_item_ref.id.hir_id();
-                            if let Some(trait_spans) = existing_name.trait_methods.get(&method_name) {
+                        for assoc_item in cx.tcx.associated_items(id.owner_id).in_definition_order() {
+                            let AssocKind::Fn { name, .. } = assoc_item.kind else { continue };
+                            let impl_span = cx.tcx.def_span(assoc_item.def_id);
+                            let hir_id = cx.tcx.local_def_id_to_hir_id(assoc_item.def_id.expect_local());
+                            if let Some(trait_spans) = existing_name.trait_methods.get(&name) {
                                 span_lint_hir_and_then(
                                     cx,
                                     SAME_NAME_METHOD,
@@ -148,12 +142,12 @@ impl<'tcx> LateLintPass<'tcx> for SameNameMethod {
                                         // iterate on trait_spans?
                                         diag.span_note(
                                             trait_spans[0],
-                                            format!("existing `{method_name}` defined here"),
+                                            format!("existing `{name}` defined here"),
                                         );
                                     },
                                 );
                             }
-                            existing_name.impl_methods.insert(method_name, (impl_span, hir_id));
+                            existing_name.impl_methods.insert(name, (impl_span, hir_id));
                         }
                     },
                 }
diff --git a/src/tools/clippy/clippy_lints/src/serde_api.rs b/src/tools/clippy/clippy_lints/src/serde_api.rs
index b36a5d6d502ea..2de22e4b6a360 100644
--- a/src/tools/clippy/clippy_lints/src/serde_api.rs
+++ b/src/tools/clippy/clippy_lints/src/serde_api.rs
@@ -36,9 +36,9 @@ impl<'tcx> LateLintPass<'tcx> for SerdeApi {
                 let mut seen_str = None;
                 let mut seen_string = None;
                 for item in *items {
-                    match item.ident.name {
-                        sym::visit_str => seen_str = Some(item.span),
-                        sym::visit_string => seen_string = Some(item.span),
+                    match cx.tcx.item_name(item.owner_id) {
+                        sym::visit_str => seen_str = Some(cx.tcx.def_span(item.owner_id)),
+                        sym::visit_string => seen_string = Some(cx.tcx.def_span(item.owner_id)),
                         _ => {},
                     }
                 }
diff --git a/src/tools/clippy/clippy_utils/src/paths.rs b/src/tools/clippy/clippy_utils/src/paths.rs
index 8bbcb220210af..c681806517afb 100644
--- a/src/tools/clippy/clippy_utils/src/paths.rs
+++ b/src/tools/clippy/clippy_utils/src/paths.rs
@@ -10,7 +10,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def::Namespace::{MacroNS, TypeNS, ValueNS};
 use rustc_hir::def::{DefKind, Namespace, Res};
 use rustc_hir::def_id::{DefId, LOCAL_CRATE, LocalDefId};
-use rustc_hir::{ImplItemRef, ItemKind, Node, OwnerId, TraitItemRef, UseKind};
+use rustc_hir::{ItemKind, Node, UseKind};
 use rustc_lint::LateContext;
 use rustc_middle::ty::fast_reject::SimplifiedType;
 use rustc_middle::ty::{FloatTy, IntTy, Ty, TyCtxt, UintTy};
@@ -284,14 +284,6 @@ fn local_item_child_by_name(tcx: TyCtxt<'_>, local_id: LocalDefId, ns: PathNS, n
         _ => return None,
     };
 
-    let res = |ident: Ident, owner_id: OwnerId| {
-        if ident.name == name && ns.matches(tcx.def_kind(owner_id).ns()) {
-            Some(owner_id.to_def_id())
-        } else {
-            None
-        }
-    };
-
     match item_kind {
         ItemKind::Mod(_, r#mod) => r#mod.item_ids.iter().find_map(|&item_id| {
             let item = tcx.hir_item(item_id);
@@ -307,17 +299,19 @@ fn local_item_child_by_name(tcx: TyCtxt<'_>, local_id: LocalDefId, ns: PathNS, n
                 } else {
                     None
                 }
+            } else if let Some(ident) = item.kind.ident()
+                && ident.name == name
+                && ns.matches(tcx.def_kind(item.owner_id).ns())
+            {
+                Some(item.owner_id.to_def_id())
             } else {
-                res(item.kind.ident()?, item_id.owner_id)
+                None
             }
         }),
-        ItemKind::Impl(r#impl) => r#impl
-            .items
-            .iter()
-            .find_map(|&ImplItemRef { ident, id, .. }| res(ident, id.owner_id)),
-        ItemKind::Trait(.., trait_item_refs) => trait_item_refs
-            .iter()
-            .find_map(|&TraitItemRef { ident, id, .. }| res(ident, id.owner_id)),
+        ItemKind::Impl(..) | ItemKind::Trait(..)
+            => tcx.associated_items(local_id).filter_by_name_unhygienic(name)
+                .find(|assoc_item| ns.matches(Some(assoc_item.namespace())))
+                .map(|assoc_item| assoc_item.def_id),
         _ => None,
     }
 }
diff --git a/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.default.stderr b/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.default.stderr
index a3c35a31c3314..87e4b0c5c7d0a 100644
--- a/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.default.stderr
+++ b/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.default.stderr
@@ -136,13 +136,13 @@ error: incorrect ordering of trait items (defined order: [Const, Type, Fn])
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.rs:155:5
    |
 LL |     const A: bool;
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
    |
 note: should be placed before `SomeType`
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.rs:153:5
    |
 LL |     type SomeType;
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
 
 error: incorrect ordering of items (must be alphabetically ordered)
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.rs:171:11
@@ -172,13 +172,13 @@ error: incorrect ordering of impl items (defined order: [Const, Type, Fn])
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.rs:189:5
    |
 LL |     const A: bool = false;
-   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
    |
 note: should be placed before `SomeType`
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.rs:187:5
    |
 LL |     type SomeType = ();
-   |     ^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
 
 error: aborting due to 15 previous errors
 
diff --git a/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.default_exp.stderr b/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.default_exp.stderr
index a3c35a31c3314..87e4b0c5c7d0a 100644
--- a/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.default_exp.stderr
+++ b/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.default_exp.stderr
@@ -136,13 +136,13 @@ error: incorrect ordering of trait items (defined order: [Const, Type, Fn])
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.rs:155:5
    |
 LL |     const A: bool;
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
    |
 note: should be placed before `SomeType`
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.rs:153:5
    |
 LL |     type SomeType;
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
 
 error: incorrect ordering of items (must be alphabetically ordered)
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.rs:171:11
@@ -172,13 +172,13 @@ error: incorrect ordering of impl items (defined order: [Const, Type, Fn])
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.rs:189:5
    |
 LL |     const A: bool = false;
-   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
    |
 note: should be placed before `SomeType`
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.rs:187:5
    |
 LL |     type SomeType = ();
-   |     ^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
 
 error: aborting due to 15 previous errors
 
diff --git a/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.ord_within.stderr b/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.ord_within.stderr
index 3fdd706fc627f..40505e2a1c452 100644
--- a/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.ord_within.stderr
+++ b/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.ord_within.stderr
@@ -211,13 +211,13 @@ error: incorrect ordering of trait items (defined order: [Const, Type, Fn])
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.rs:155:5
    |
 LL |     const A: bool;
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
    |
 note: should be placed before `SomeType`
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.rs:153:5
    |
 LL |     type SomeType;
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
 
 error: incorrect ordering of items (must be alphabetically ordered)
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.rs:171:11
@@ -247,13 +247,13 @@ error: incorrect ordering of impl items (defined order: [Const, Type, Fn])
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.rs:189:5
    |
 LL |     const A: bool = false;
-   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
    |
 note: should be placed before `SomeType`
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.rs:187:5
    |
 LL |     type SomeType = ();
-   |     ^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
 
 error: incorrect ordering of items (must be alphabetically ordered)
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed.rs:207:11
diff --git a/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed_var_1.var_1.stderr b/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed_var_1.var_1.stderr
index 730f12c38a0d3..d8db2243d4171 100644
--- a/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed_var_1.var_1.stderr
+++ b/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed_var_1.var_1.stderr
@@ -28,25 +28,25 @@ error: incorrect ordering of impl items (defined order: [Fn, Type, Const])
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed_var_1.rs:119:5
    |
 LL |     type SomeType = ();
-   |     ^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
    |
 note: should be placed before `A`
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed_var_1.rs:117:5
    |
 LL |     const A: bool = false;
-   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
 
 error: incorrect ordering of impl items (defined order: [Fn, Type, Const])
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed_var_1.rs:122:5
    |
 LL |     fn a() {}
-   |     ^^^^^^^^^
+   |     ^^^^^^
    |
 note: should be placed before `SomeType`
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed_var_1.rs:119:5
    |
 LL |     type SomeType = ();
-   |     ^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
 
 error: incorrect ordering of items (must be alphabetically ordered)
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed_var_1.rs:149:8
@@ -76,13 +76,13 @@ error: incorrect ordering of trait items (defined order: [Fn, Type, Const])
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed_var_1.rs:163:5
    |
 LL |     type SomeType;
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
    |
 note: should be placed before `A`
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed_var_1.rs:161:5
    |
 LL |     const A: bool;
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
 
 error: incorrect ordering of trait items (defined order: [Fn, Type, Const])
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed_var_1.rs:166:5
@@ -94,7 +94,7 @@ note: should be placed before `SomeType`
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_mixed_var_1.rs:163:5
    |
 LL |     type SomeType;
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
 
 error: aborting due to 8 previous errors
 
diff --git a/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_only_impl.only_impl.stderr b/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_only_impl.only_impl.stderr
index 77596ba23946d..7f6bddf8005fe 100644
--- a/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_only_impl.only_impl.stderr
+++ b/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_only_impl.only_impl.stderr
@@ -16,25 +16,25 @@ error: incorrect ordering of impl items (defined order: [Const, Type, Fn])
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_only_impl.rs:46:5
    |
 LL |     type SomeType = i8;
-   |     ^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
    |
 note: should be placed before `a`
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_only_impl.rs:43:5
    |
 LL |     fn a() {}
-   |     ^^^^^^^^^
+   |     ^^^^^^
 
 error: incorrect ordering of impl items (defined order: [Const, Type, Fn])
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_only_impl.rs:49:5
    |
 LL |     const A: bool = true;
-   |     ^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
    |
 note: should be placed before `SomeType`
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_only_impl.rs:46:5
    |
 LL |     type SomeType = i8;
-   |     ^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
 
 error: aborting due to 3 previous errors
 
diff --git a/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_only_trait.only_trait.stderr b/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_only_trait.only_trait.stderr
index 3d903330be8f5..a7cff238b785b 100644
--- a/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_only_trait.only_trait.stderr
+++ b/src/tools/clippy/tests/ui-toml/arbitrary_source_item_ordering/ordering_only_trait.only_trait.stderr
@@ -28,13 +28,13 @@ error: incorrect ordering of trait items (defined order: [Const, Type, Fn])
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_only_trait.rs:45:5
    |
 LL |     const A: bool;
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
    |
 note: should be placed before `SomeType`
   --> tests/ui-toml/arbitrary_source_item_ordering/ordering_only_trait.rs:43:5
    |
 LL |     type SomeType;
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^
 
 error: aborting due to 3 previous errors
 
diff --git a/src/tools/clippy/tests/ui/partialeq_ne_impl.stderr b/src/tools/clippy/tests/ui/partialeq_ne_impl.stderr
index dc01a375060b9..0f700654f7ccc 100644
--- a/src/tools/clippy/tests/ui/partialeq_ne_impl.stderr
+++ b/src/tools/clippy/tests/ui/partialeq_ne_impl.stderr
@@ -1,12 +1,8 @@
 error: re-implementing `PartialEq::ne` is unnecessary
   --> tests/ui/partialeq_ne_impl.rs:9:5
    |
-LL | /     fn ne(&self, _: &Foo) -> bool {
-LL | |
-LL | |
-LL | |         false
-LL | |     }
-   | |_____^
+LL |     fn ne(&self, _: &Foo) -> bool {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D clippy::partialeq-ne-impl` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::partialeq_ne_impl)]`
diff --git a/src/tools/clippy/tests/ui/same_name_method.stderr b/src/tools/clippy/tests/ui/same_name_method.stderr
index b2624ac4d2644..bf7456d80e2a3 100644
--- a/src/tools/clippy/tests/ui/same_name_method.stderr
+++ b/src/tools/clippy/tests/ui/same_name_method.stderr
@@ -2,13 +2,13 @@ error: method's name is the same as an existing method in a trait
   --> tests/ui/same_name_method.rs:20:13
    |
 LL |             fn foo() {}
-   |             ^^^^^^^^^^^
+   |             ^^^^^^^^
    |
 note: existing `foo` defined here
   --> tests/ui/same_name_method.rs:25:13
    |
 LL |             fn foo() {}
-   |             ^^^^^^^^^^^
+   |             ^^^^^^^^
    = note: `-D clippy::same-name-method` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::same_name_method)]`
 
@@ -16,7 +16,7 @@ error: method's name is the same as an existing method in a trait
   --> tests/ui/same_name_method.rs:35:13
    |
 LL |             fn clone() {}
-   |             ^^^^^^^^^^^^^
+   |             ^^^^^^^^^^
    |
 note: existing `clone` defined here
   --> tests/ui/same_name_method.rs:31:18
@@ -28,19 +28,19 @@ error: method's name is the same as an existing method in a trait
   --> tests/ui/same_name_method.rs:46:13
    |
 LL |             fn foo() {}
-   |             ^^^^^^^^^^^
+   |             ^^^^^^^^
    |
 note: existing `foo` defined here
   --> tests/ui/same_name_method.rs:51:13
    |
 LL |             fn foo() {}
-   |             ^^^^^^^^^^^
+   |             ^^^^^^^^
 
 error: method's name is the same as an existing method in a trait
   --> tests/ui/same_name_method.rs:61:13
    |
 LL |             fn foo() {}
-   |             ^^^^^^^^^^^
+   |             ^^^^^^^^
    |
 note: existing `foo` defined here
   --> tests/ui/same_name_method.rs:65:9
@@ -52,7 +52,7 @@ error: method's name is the same as an existing method in a trait
   --> tests/ui/same_name_method.rs:74:13
    |
 LL |             fn foo() {}
-   |             ^^^^^^^^^^^
+   |             ^^^^^^^^
    |
 note: existing `foo` defined here
   --> tests/ui/same_name_method.rs:79:9
@@ -64,7 +64,7 @@ error: method's name is the same as an existing method in a trait
   --> tests/ui/same_name_method.rs:74:13
    |
 LL |             fn foo() {}
-   |             ^^^^^^^^^^^
+   |             ^^^^^^^^
    |
 note: existing `foo` defined here
   --> tests/ui/same_name_method.rs:81:9
diff --git a/src/tools/clippy/tests/ui/serde.stderr b/src/tools/clippy/tests/ui/serde.stderr
index eb6b7c6b0c36a..652248e3578c7 100644
--- a/src/tools/clippy/tests/ui/serde.stderr
+++ b/src/tools/clippy/tests/ui/serde.stderr
@@ -5,10 +5,7 @@ LL | /     fn visit_string<E>(self, _v: String) -> Result<Self::Value, E>
 LL | |
 LL | |     where
 LL | |         E: serde::de::Error,
-LL | |     {
-LL | |         unimplemented!()
-LL | |     }
-   | |_____^
+   | |____________________________^
    |
    = note: `-D clippy::serde-api-misuse` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::serde_api_misuse)]`
diff --git a/tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-paths.rs b/tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-paths.rs
index a8ba8db1be3b4..e1527bf1edc2d 100644
--- a/tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-paths.rs
+++ b/tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-paths.rs
@@ -78,9 +78,9 @@ pub fn foo12(_: &Type4, _: &Type4, _: &Type4) {}
 // CHECK: ![[TYPE4]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NtNCNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo11{{[{}][{}]}}closure{{[}][}]}}3FooEE"}
 // CHECK: ![[TYPE5]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NtNCNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo11{{[{}][{}]}}closure{{[}][}]}}3FooES0_E"}
 // CHECK: ![[TYPE6]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NtNCNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo11{{[{}][{}]}}closure{{[}][}]}}3FooES0_S0_E"}
-// CHECK: ![[TYPE7]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NtNkNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo12{{[{}][{}]}}constant{{[}][}]}}3FooEE"}
-// CHECK: ![[TYPE8]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NtNkNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo12{{[{}][{}]}}constant{{[}][}]}}3FooES0_E"}
-// CHECK: ![[TYPE9]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NtNkNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo12{{[{}][{}]}}constant{{[}][}]}}3FooES0_S0_E"}
+// CHECK: ![[TYPE7]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NtNKNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo12{{[{}][{}]}}constant{{[}][}]}}3FooEE"}
+// CHECK: ![[TYPE8]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NtNKNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo12{{[{}][{}]}}constant{{[}][}]}}3FooES0_E"}
+// CHECK: ![[TYPE9]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NtNKNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo12{{[{}][{}]}}constant{{[}][}]}}3FooES0_S0_E"}
 // CHECK: ![[TYPE10]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NvNINvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo8{{[{}][{}]}}impl{{[}][}]}}3barEE"}
 // CHECK: ![[TYPE11]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NvNINvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo8{{[{}][{}]}}impl{{[}][}]}}3barES0_E"}
 // CHECK: ![[TYPE12]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NvNINvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo8{{[{}][{}]}}impl{{[}][}]}}3barES0_S0_E"}
diff --git a/tests/incremental/hashes/inherent_impls.rs b/tests/incremental/hashes/inherent_impls.rs
index caea394977a73..044c3d2b86c13 100644
--- a/tests/incremental/hashes/inherent_impls.rs
+++ b/tests/incremental/hashes/inherent_impls.rs
@@ -150,7 +150,7 @@ impl Foo {
 }
 
 #[cfg(not(any(cfail1,cfail4)))]
-#[rustc_clean(cfg="cfail2", except="opt_hir_owner_nodes")]
+#[rustc_clean(cfg="cfail2")]
 #[rustc_clean(cfg="cfail3")]
 #[rustc_clean(cfg="cfail5", except="opt_hir_owner_nodes")]
 #[rustc_clean(cfg="cfail6")]
diff --git a/tests/incremental/hashes/trait_impls.rs b/tests/incremental/hashes/trait_impls.rs
index 8faf6806b90b4..a89b5b3e78298 100644
--- a/tests/incremental/hashes/trait_impls.rs
+++ b/tests/incremental/hashes/trait_impls.rs
@@ -141,7 +141,7 @@ pub trait ChangeMethodSelfnessTrait {
 }
 
 #[cfg(not(any(cfail1,cfail4)))]
-#[rustc_clean(except="opt_hir_owner_nodes", cfg="cfail2")]
+#[rustc_clean(cfg="cfail2")]
 #[rustc_clean(cfg="cfail3")]
 #[rustc_clean(except="opt_hir_owner_nodes", cfg="cfail5")]
 #[rustc_clean(cfg="cfail6")]
@@ -179,7 +179,7 @@ pub trait RemoveMethodSelfnessTrait {
 }
 
 #[cfg(not(any(cfail1,cfail4)))]
-#[rustc_clean(except="opt_hir_owner_nodes", cfg="cfail2")]
+#[rustc_clean(cfg="cfail2")]
 #[rustc_clean(cfg="cfail3")]
 #[rustc_clean(except="opt_hir_owner_nodes", cfg="cfail5")]
 #[rustc_clean(cfg="cfail6")]
diff --git a/tests/ui/associated-consts/issue-58022.stderr b/tests/ui/associated-consts/issue-58022.stderr
index 37cb162b2b221..5d57e01d6f59c 100644
--- a/tests/ui/associated-consts/issue-58022.stderr
+++ b/tests/ui/associated-consts/issue-58022.stderr
@@ -16,7 +16,7 @@ error[E0790]: cannot refer to the associated constant on trait without specifyin
   --> $DIR/issue-58022.rs:4:25
    |
 LL |     const SIZE: usize;
-   |     ------------------ `Foo::SIZE` defined here
+   |     ----------------- `Foo::SIZE` defined here
 LL |
 LL |     fn new(slice: &[u8; Foo::SIZE]) -> Self;
    |                         ^^^^^^^^^ cannot refer to the associated constant of trait
diff --git a/tests/ui/associated-consts/issue-63496.stderr b/tests/ui/associated-consts/issue-63496.stderr
index f2a4e01adea43..bdd2769afc86a 100644
--- a/tests/ui/associated-consts/issue-63496.stderr
+++ b/tests/ui/associated-consts/issue-63496.stderr
@@ -2,7 +2,7 @@ error[E0790]: cannot refer to the associated constant on trait without specifyin
   --> $DIR/issue-63496.rs:4:21
    |
 LL |     const C: usize;
-   |     --------------- `A::C` defined here
+   |     -------------- `A::C` defined here
 LL |
 LL |     fn f() -> ([u8; A::C], [u8; A::C]);
    |                     ^^^^ cannot refer to the associated constant of trait
@@ -11,7 +11,7 @@ error[E0790]: cannot refer to the associated constant on trait without specifyin
   --> $DIR/issue-63496.rs:4:33
    |
 LL |     const C: usize;
-   |     --------------- `A::C` defined here
+   |     -------------- `A::C` defined here
 LL |
 LL |     fn f() -> ([u8; A::C], [u8; A::C]);
    |                                 ^^^^ cannot refer to the associated constant of trait
diff --git a/tests/ui/associated-item/issue-48027.stderr b/tests/ui/associated-item/issue-48027.stderr
index 513961e2bd0ad..e5c1ced934136 100644
--- a/tests/ui/associated-item/issue-48027.stderr
+++ b/tests/ui/associated-item/issue-48027.stderr
@@ -18,7 +18,7 @@ error[E0790]: cannot refer to the associated constant on trait without specifyin
   --> $DIR/issue-48027.rs:3:32
    |
 LL |     const X: usize;
-   |     --------------- `Bar::X` defined here
+   |     -------------- `Bar::X` defined here
 LL |     fn return_n(&self) -> [u8; Bar::X];
    |                                ^^^^^^ cannot refer to the associated constant of trait
 
diff --git a/tests/ui/associated-types/defaults-in-other-trait-items.stderr b/tests/ui/associated-types/defaults-in-other-trait-items.stderr
index bdcfadd3955d2..56abd6ebf73b2 100644
--- a/tests/ui/associated-types/defaults-in-other-trait-items.stderr
+++ b/tests/ui/associated-types/defaults-in-other-trait-items.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/defaults-in-other-trait-items.rs:9:13
    |
 LL |     type A = ();
-   |     ------------ associated type defaults can't be assumed inside the trait defining them
+   |     ------ associated type defaults can't be assumed inside the trait defining them
 ...
 LL |         let () = p;
    |             ^^   - this expression has type `<Self as Tr>::A`
@@ -16,7 +16,7 @@ error[E0308]: mismatched types
   --> $DIR/defaults-in-other-trait-items.rs:36:25
    |
 LL |     type Ty = u8;
-   |     ------------- associated type defaults can't be assumed inside the trait defining them
+   |     ------- associated type defaults can't be assumed inside the trait defining them
 ...
 LL |     const C: Self::Ty = 0u8;
    |                         ^^^ expected associated type, found `u8`
@@ -28,7 +28,7 @@ error[E0308]: mismatched types
   --> $DIR/defaults-in-other-trait-items.rs:54:9
    |
 LL |     type Res = isize;
-   |     ----------------- associated type defaults can't be assumed inside the trait defining them
+   |     -------- associated type defaults can't be assumed inside the trait defining them
 LL |
 LL |     fn infer_me_correctly() -> Self::Res {
    |                                --------- expected `<Self as Trait>::Res` because of return type
diff --git a/tests/ui/associated-types/defaults-specialization.stderr b/tests/ui/associated-types/defaults-specialization.stderr
index fd2a1a0c2d13a..7d19ac85982a3 100644
--- a/tests/ui/associated-types/defaults-specialization.stderr
+++ b/tests/ui/associated-types/defaults-specialization.stderr
@@ -31,7 +31,7 @@ error[E0053]: method `make` has an incompatible type for trait
   --> $DIR/defaults-specialization.rs:35:18
    |
 LL |     default type Ty = bool;
-   |     ----------------------- associated type is `default` and may be overridden
+   |     --------------- associated type is `default` and may be overridden
 LL |
 LL |     fn make() -> bool { true }
    |                  ^^^^ expected associated type, found `bool`
@@ -53,7 +53,7 @@ error[E0308]: mismatched types
   --> $DIR/defaults-specialization.rs:10:9
    |
 LL |     type Ty = u8;
-   |     ------------- associated type defaults can't be assumed inside the trait defining them
+   |     ------- associated type defaults can't be assumed inside the trait defining them
 LL |
 LL |     fn make() -> Self::Ty {
    |                  -------- expected `<Self as Tr>::Ty` because of return type
@@ -80,7 +80,7 @@ error[E0308]: mismatched types
   --> $DIR/defaults-specialization.rs:44:29
    |
 LL |     default type Ty = bool;
-   |     ----------------------- associated type is `default` and may be overridden
+   |     --------------- associated type is `default` and may be overridden
 LL |
 LL |     fn make() -> Self::Ty { true }
    |                  --------   ^^^^ expected associated type, found `bool`
diff --git a/tests/ui/associated-types/issue-26681.stderr b/tests/ui/associated-types/issue-26681.stderr
index b64bcee07f043..5fb1a4ef3f5f0 100644
--- a/tests/ui/associated-types/issue-26681.stderr
+++ b/tests/ui/associated-types/issue-26681.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/issue-26681.rs:17:39
    |
 LL |     type Fv: Foo = u8;
-   |     ------------------ associated type defaults can't be assumed inside the trait defining them
+   |     ------------ associated type defaults can't be assumed inside the trait defining them
 LL |     const C: <Self::Fv as Foo>::Bar = 6665;
    |                                       ^^^^ expected associated type, found integer
    |
diff --git a/tests/ui/consts/issue-54954.stderr b/tests/ui/consts/issue-54954.stderr
index b8c983eb7b81c..2ef3abcf7603b 100644
--- a/tests/ui/consts/issue-54954.stderr
+++ b/tests/ui/consts/issue-54954.stderr
@@ -10,14 +10,11 @@ LL |     const fn const_val<T: Sized>() -> usize {
 error[E0790]: cannot call associated function on trait without specifying the corresponding `impl` type
   --> $DIR/issue-54954.rs:1:24
    |
-LL |   const ARR_LEN: usize = Tt::const_val::<[i8; 123]>();
-   |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot call associated function of trait
+LL | const ARR_LEN: usize = Tt::const_val::<[i8; 123]>();
+   |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot call associated function of trait
 ...
-LL | /     const fn const_val<T: Sized>() -> usize {
-LL | |
-LL | |         core::mem::size_of::<T>()
-LL | |     }
-   | |_____- `Tt::const_val` defined here
+LL |     const fn const_val<T: Sized>() -> usize {
+   |     --------------------------------------- `Tt::const_val` defined here
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/error-codes/E0790.stderr b/tests/ui/error-codes/E0790.stderr
index 106554b24253e..93c43020768c7 100644
--- a/tests/ui/error-codes/E0790.stderr
+++ b/tests/ui/error-codes/E0790.stderr
@@ -16,7 +16,7 @@ error[E0790]: cannot refer to the associated constant on trait without specifyin
   --> $DIR/E0790.rs:21:17
    |
 LL |         const MY_ASSOC_CONST: ();
-   |         ------------------------- `MyTrait::MY_ASSOC_CONST` defined here
+   |         ------------------------ `MyTrait::MY_ASSOC_CONST` defined here
 ...
 LL |         let _ = MyTrait::MY_ASSOC_CONST;
    |                 ^^^^^^^^^^^^^^^^^^^^^^^ cannot refer to the associated constant of trait
@@ -44,7 +44,7 @@ error[E0790]: cannot refer to the associated constant on trait without specifyin
   --> $DIR/E0790.rs:30:13
    |
 LL |         const MY_ASSOC_CONST: ();
-   |         ------------------------- `MyTrait::MY_ASSOC_CONST` defined here
+   |         ------------------------ `MyTrait::MY_ASSOC_CONST` defined here
 ...
 LL |     let _ = inner::MyTrait::MY_ASSOC_CONST;
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot refer to the associated constant of trait
diff --git a/tests/ui/feature-gates/feature-gate-async-drop.stderr b/tests/ui/feature-gates/feature-gate-async-drop.stderr
index e795c3a342269..80f6228a16fe3 100644
--- a/tests/ui/feature-gates/feature-gate-async-drop.stderr
+++ b/tests/ui/feature-gates/feature-gate-async-drop.stderr
@@ -12,7 +12,7 @@ error[E0658]: use of unstable library feature `async_drop`
   --> $DIR/feature-gate-async-drop.rs:13:5
    |
 LL |     async fn drop(self: Pin<&mut Self>) {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: see issue #126482 <https://github.com/rust-lang/rust/issues/126482> for more information
    = help: add `#![feature(async_drop)]` to the crate attributes to enable
diff --git a/tests/ui/generics/export-name-on-generics.stderr b/tests/ui/generics/export-name-on-generics.stderr
index 7bc7b8ca55931..e08b2b1c8f319 100644
--- a/tests/ui/generics/export-name-on-generics.stderr
+++ b/tests/ui/generics/export-name-on-generics.stderr
@@ -4,7 +4,7 @@ error: functions generic over types or consts must be mangled
 LL | #[export_name = "foo"]
    | ---------------------- help: remove this attribute
 LL | pub fn foo<T>() {}
-   | ^^^^^^^^^^^^^^^^^^
+   | ^^^^^^^^^^^^^^^
    |
 note: the lint level is defined here
   --> $DIR/export-name-on-generics.rs:3:9
@@ -18,7 +18,7 @@ error: functions generic over types or consts must be mangled
 LL | #[export_name = "bar"]
    | ---------------------- help: remove this attribute
 LL | pub extern "C" fn bar<T>() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/export-name-on-generics.rs:21:5
@@ -26,7 +26,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[export_name = "foo"]
    |     ---------------------- help: remove this attribute
 LL |     pub fn foo<T>() {}
-   |     ^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/export-name-on-generics.rs:24:5
@@ -34,7 +34,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[export_name = "bar"]
    |     ---------------------- help: remove this attribute
 LL |     pub extern "C" fn bar<T>() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/export-name-on-generics.rs:42:5
@@ -42,7 +42,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[export_name = "foo"]
    |     ---------------------- help: remove this attribute
 LL |     fn foo<T>() {}
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/export-name-on-generics.rs:45:5
@@ -50,7 +50,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[export_name = "bar"]
    |     ---------------------- help: remove this attribute
 LL |     extern "C" fn bar<T>() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/export-name-on-generics.rs:64:5
@@ -58,7 +58,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[export_name = "foo"]
    |     ---------------------- help: remove this attribute
 LL |     fn foo() {}
-   |     ^^^^^^^^^^^
+   |     ^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/export-name-on-generics.rs:67:5
@@ -66,7 +66,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[export_name = "foo2"]
    |     ----------------------- help: remove this attribute
 LL |     fn foo2<U>() {}
-   |     ^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/export-name-on-generics.rs:70:5
@@ -74,7 +74,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[export_name = "baz"]
    |     ---------------------- help: remove this attribute
 LL |     extern "C" fn bar() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/export-name-on-generics.rs:73:5
@@ -82,7 +82,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[export_name = "baz"]
    |     ---------------------- help: remove this attribute
 LL |     fn baz(x: &i32) -> &i32 { x }
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/export-name-on-generics.rs:76:5
@@ -90,7 +90,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[export_name = "qux"]
    |     ---------------------- help: remove this attribute
 LL |     fn qux<'a>(x: &'a i32) -> &i32 { x }
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/export-name-on-generics.rs:83:5
@@ -98,7 +98,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[export_name = "foo"]
    |     ---------------------- help: remove this attribute
 LL |     pub fn foo() {}
-   |     ^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/export-name-on-generics.rs:86:5
@@ -106,7 +106,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[export_name = "bar"]
    |     ---------------------- help: remove this attribute
 LL |     pub extern "C" fn bar() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/export-name-on-generics.rs:89:5
@@ -114,7 +114,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[export_name = "baz"]
    |     ---------------------- help: remove this attribute
 LL |     pub fn baz<U>() {}
-   |     ^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/export-name-on-generics.rs:105:5
@@ -122,7 +122,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[export_name = "foo"]
    |     ---------------------- help: remove this attribute
 LL |     fn foo() {}
-   |     ^^^^^^^^^^^
+   |     ^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/export-name-on-generics.rs:108:5
@@ -130,7 +130,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[export_name = "bar"]
    |     ---------------------- help: remove this attribute
 LL |     extern "C" fn bar() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/export-name-on-generics.rs:111:5
@@ -138,7 +138,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[export_name = "baz"]
    |     ---------------------- help: remove this attribute
 LL |     fn baz<U>() {}
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^
 
 error: aborting due to 17 previous errors
 
diff --git a/tests/ui/generics/generic-no-mangle.stderr b/tests/ui/generics/generic-no-mangle.stderr
index adfddbe9ca791..39fbe4dd76da1 100644
--- a/tests/ui/generics/generic-no-mangle.stderr
+++ b/tests/ui/generics/generic-no-mangle.stderr
@@ -4,7 +4,7 @@ error: functions generic over types or consts must be mangled
 LL | #[no_mangle]
    | ------------ help: remove this attribute
 LL | pub fn foo<T>() {}
-   | ^^^^^^^^^^^^^^^^^^
+   | ^^^^^^^^^^^^^^^
    |
 note: the lint level is defined here
   --> $DIR/generic-no-mangle.rs:3:9
@@ -18,7 +18,7 @@ error: functions generic over types or consts must be mangled
 LL | #[no_mangle]
    | ------------ help: remove this attribute
 LL | pub extern "C" fn bar<T>() {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/generic-no-mangle.rs:21:5
@@ -26,7 +26,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[no_mangle]
    |     ------------ help: remove this attribute
 LL |     pub fn foo<T>() {}
-   |     ^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/generic-no-mangle.rs:24:5
@@ -34,7 +34,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[no_mangle]
    |     ------------ help: remove this attribute
 LL |     pub extern "C" fn bar<T>() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/generic-no-mangle.rs:42:5
@@ -42,7 +42,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[no_mangle]
    |     ------------ help: remove this attribute
 LL |     fn foo<T>() {}
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/generic-no-mangle.rs:45:5
@@ -50,7 +50,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[no_mangle]
    |     ------------ help: remove this attribute
 LL |     extern "C" fn bar<T>() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/generic-no-mangle.rs:64:5
@@ -58,7 +58,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[no_mangle]
    |     ------------ help: remove this attribute
 LL |     fn foo() {}
-   |     ^^^^^^^^^^^
+   |     ^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/generic-no-mangle.rs:67:5
@@ -66,7 +66,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[no_mangle]
    |     ------------ help: remove this attribute
 LL |     fn foo2<U>() {}
-   |     ^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/generic-no-mangle.rs:70:5
@@ -74,7 +74,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[no_mangle]
    |     ------------ help: remove this attribute
 LL |     extern "C" fn bar() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/generic-no-mangle.rs:73:5
@@ -82,7 +82,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[no_mangle]
    |     ------------ help: remove this attribute
 LL |     fn baz(x: &i32) -> &i32 { x }
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/generic-no-mangle.rs:76:5
@@ -90,7 +90,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[no_mangle]
    |     ------------ help: remove this attribute
 LL |     fn qux<'a>(x: &'a i32) -> &i32 { x }
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/generic-no-mangle.rs:83:5
@@ -98,7 +98,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[no_mangle]
    |     ------------ help: remove this attribute
 LL |     pub fn foo() {}
-   |     ^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/generic-no-mangle.rs:86:5
@@ -106,7 +106,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[no_mangle]
    |     ------------ help: remove this attribute
 LL |     pub extern "C" fn bar() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/generic-no-mangle.rs:89:5
@@ -114,7 +114,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[no_mangle]
    |     ------------ help: remove this attribute
 LL |     pub fn baz<U>() {}
-   |     ^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/generic-no-mangle.rs:105:5
@@ -122,7 +122,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[no_mangle]
    |     ------------ help: remove this attribute
 LL |     fn foo() {}
-   |     ^^^^^^^^^^^
+   |     ^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/generic-no-mangle.rs:108:5
@@ -130,7 +130,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[no_mangle]
    |     ------------ help: remove this attribute
 LL |     extern "C" fn bar() {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^
 
 error: functions generic over types or consts must be mangled
   --> $DIR/generic-no-mangle.rs:111:5
@@ -138,7 +138,7 @@ error: functions generic over types or consts must be mangled
 LL |     #[no_mangle]
    |     ------------ help: remove this attribute
 LL |     fn baz<U>() {}
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^
 
 error: aborting due to 17 previous errors
 
diff --git a/tests/ui/invalid/invalid-rustc_legacy_const_generics-issue-123077.stderr b/tests/ui/invalid/invalid-rustc_legacy_const_generics-issue-123077.stderr
index 6f5d719006d8f..111d6d524e5fb 100644
--- a/tests/ui/invalid/invalid-rustc_legacy_const_generics-issue-123077.stderr
+++ b/tests/ui/invalid/invalid-rustc_legacy_const_generics-issue-123077.stderr
@@ -67,9 +67,10 @@ LL |         struct F();
 help: try using a const generic argument instead
    |
 LL ~     std::arch::x86_64::_mm_blend_ps::<{ {
-LL +     struct F();
-LL +     1
-LL ~ } }>(loop {}, loop {});
+LL +         struct F();
+LL +
+LL +         1
+LL ~     } }>(loop {}, loop {});
    |
 
 error: invalid argument to a legacy const generic: cannot have const blocks, closures, async blocks or items
diff --git a/tests/ui/lint/lint-stability.stderr b/tests/ui/lint/lint-stability.stderr
index a22fce70a4ad5..fd57908a77b53 100644
--- a/tests/ui/lint/lint-stability.stderr
+++ b/tests/ui/lint/lint-stability.stderr
@@ -290,7 +290,7 @@ error[E0658]: use of unstable library feature `unstable_test_feature`
   --> $DIR/lint-stability.rs:179:9
    |
 LL |         fn trait_unstable(&self) {}
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(unstable_test_feature)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
diff --git a/tests/ui/lint/suggestions.stderr b/tests/ui/lint/suggestions.stderr
index a4871ead74b8b..c35e92f59809a 100644
--- a/tests/ui/lint/suggestions.stderr
+++ b/tests/ui/lint/suggestions.stderr
@@ -65,7 +65,7 @@ LL | #[no_mangle]
    | ------------ help: remove this attribute
 LL |
 LL | pub fn defiant<T>(_t: T) {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(no_mangle_generic_items)]` on by default
 
@@ -89,7 +89,7 @@ warning: functions generic over types or consts must be mangled
   --> $DIR/suggestions.rs:26:18
    |
 LL |     #[no_mangle] pub fn val_jean<T>() {}
-   |     ------------ ^^^^^^^^^^^^^^^^^^^^^^^
+   |     ------------ ^^^^^^^^^^^^^^^^^^^^
    |     |
    |     help: remove this attribute
 
@@ -105,7 +105,7 @@ warning: functions generic over types or consts must be mangled
   --> $DIR/suggestions.rs:35:18
    |
 LL |     #[no_mangle] pub(crate) fn crossfield<T>() {}
-   |     ------------ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ------------ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |     |
    |     help: remove this attribute
 
diff --git a/tests/ui/specialization/specialization-default-types.current.stderr b/tests/ui/specialization/specialization-default-types.current.stderr
index 67477f9a6d537..09689681740ff 100644
--- a/tests/ui/specialization/specialization-default-types.current.stderr
+++ b/tests/ui/specialization/specialization-default-types.current.stderr
@@ -12,7 +12,7 @@ error[E0308]: mismatched types
   --> $DIR/specialization-default-types.rs:19:9
    |
 LL |     default type Output = Box<T>;
-   |     ----------------------------- associated type is `default` and may be overridden
+   |     ------------------- associated type is `default` and may be overridden
 LL |     default fn generate(self) -> Self::Output {
    |                                  ------------ expected `<T as Example>::Output` because of return type
 LL |         Box::new(self)
diff --git a/tests/ui/specialization/specialization-default-types.next.stderr b/tests/ui/specialization/specialization-default-types.next.stderr
index 4f7c47654460e..1535c6473bddf 100644
--- a/tests/ui/specialization/specialization-default-types.next.stderr
+++ b/tests/ui/specialization/specialization-default-types.next.stderr
@@ -12,7 +12,7 @@ error[E0308]: mismatched types
   --> $DIR/specialization-default-types.rs:19:9
    |
 LL |     default type Output = Box<T>;
-   |     ----------------------------- associated type is `default` and may be overridden
+   |     ------------------- associated type is `default` and may be overridden
 LL |     default fn generate(self) -> Self::Output {
    |                                  ------------ expected `<T as Example>::Output` because of return type
 LL |         Box::new(self)
diff --git a/tests/ui/stats/input-stats.stderr b/tests/ui/stats/input-stats.stderr
index eb038bbcaf1a2..72a9820bb6431 100644
--- a/tests/ui/stats/input-stats.stderr
+++ b/tests/ui/stats/input-stats.stderr
@@ -107,17 +107,17 @@ hir-stats WherePredicate            72 (NN.N%)             3            24
 hir-stats - BoundPredicate            72 (NN.N%)             3
 hir-stats Local                     72 (NN.N%)             1            72
 hir-stats InlineAsm                 72 (NN.N%)             1            72
-hir-stats ImplItemRef               72 (NN.N%)             2            36
 hir-stats Body                      72 (NN.N%)             3            24
 hir-stats Param                     64 (NN.N%)             2            32
 hir-stats GenericArg                64 (NN.N%)             4            16
 hir-stats - Type                      16 (NN.N%)             1
 hir-stats - Lifetime                  48 (NN.N%)             3
-hir-stats TraitItemRef              56 (NN.N%)             2            28
 hir-stats ExprField                 40 (NN.N%)             1            40
 hir-stats Mod                       32 (NN.N%)             1            32
 hir-stats Lifetime                  28 (NN.N%)             1            28
-hir-stats ForeignItemRef            24 (NN.N%)             1            24
+hir-stats TraitItemId                8 (NN.N%)             2             4
+hir-stats ImplItemId                 8 (NN.N%)             2             4
+hir-stats ForeignItemId              4 (NN.N%)             1             4
 hir-stats ----------------------------------------------------------------
-hir-stats Total                  8_716                   173
+hir-stats Total                  8_584                   173
 hir-stats ================================================================
diff --git a/tests/ui/suggestions/issue-104327.stderr b/tests/ui/suggestions/issue-104327.stderr
index 1bad82d471e04..4515fe223c7d9 100644
--- a/tests/ui/suggestions/issue-104327.stderr
+++ b/tests/ui/suggestions/issue-104327.stderr
@@ -2,7 +2,7 @@ error[E0790]: cannot call associated function on trait without specifying the co
   --> $DIR/issue-104327.rs:10:5
    |
 LL |     fn f() {}
-   |     --------- `Foo::f` defined here
+   |     ------ `Foo::f` defined here
 ...
 LL |     Foo::f();
    |     ^^^^^^^^ cannot call associated function of trait
diff --git a/tests/ui/traits/default-method/rustc_must_implement_one_of_misuse.stderr b/tests/ui/traits/default-method/rustc_must_implement_one_of_misuse.stderr
index 38e692521ca23..cf197d035b38f 100644
--- a/tests/ui/traits/default-method/rustc_must_implement_one_of_misuse.stderr
+++ b/tests/ui/traits/default-method/rustc_must_implement_one_of_misuse.stderr
@@ -50,7 +50,7 @@ error: not a function
   --> $DIR/rustc_must_implement_one_of_misuse.rs:26:5
    |
 LL |     const A: u8 = 1;
-   |     ^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^
    |
 note: required by this annotation
   --> $DIR/rustc_must_implement_one_of_misuse.rs:24:1
@@ -63,7 +63,7 @@ error: not a function
   --> $DIR/rustc_must_implement_one_of_misuse.rs:28:5
    |
 LL |     type B;
-   |     ^^^^^^^
+   |     ^^^^^^
    |
 note: required by this annotation
   --> $DIR/rustc_must_implement_one_of_misuse.rs:24:1
diff --git a/tests/ui/traits/trait-upcasting/deref-upcast-shadowing-lint.stderr b/tests/ui/traits/trait-upcasting/deref-upcast-shadowing-lint.stderr
index 0d7f957a50ebd..6744899e9518f 100644
--- a/tests/ui/traits/trait-upcasting/deref-upcast-shadowing-lint.stderr
+++ b/tests/ui/traits/trait-upcasting/deref-upcast-shadowing-lint.stderr
@@ -5,7 +5,7 @@ LL | impl<'a> Deref for dyn Foo + 'a {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `dyn Foo` implements `Deref<Target = dyn Bar<u32>>` which conflicts with supertrait `Bar<i32>`
 LL |
 LL |     type Target = dyn Bar<u32> + 'a;
-   |     -------------------------------- target type is a supertrait of `dyn Foo`
+   |     ----------- target type is a supertrait of `dyn Foo`
    |
 note: the lint level is defined here
   --> $DIR/deref-upcast-shadowing-lint.rs:2:9
diff --git a/tests/ui/traits/trait-upcasting/migrate-lint-deny-regions.stderr b/tests/ui/traits/trait-upcasting/migrate-lint-deny-regions.stderr
index 806c57e44a2bf..0d43563e1ab78 100644
--- a/tests/ui/traits/trait-upcasting/migrate-lint-deny-regions.stderr
+++ b/tests/ui/traits/trait-upcasting/migrate-lint-deny-regions.stderr
@@ -5,7 +5,7 @@ LL | impl<'a> Deref for dyn Foo<'a> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `dyn Foo<'_>` implements `Deref<Target = dyn Bar<'_>>` which conflicts with supertrait `Bar<'_>`
 LL |
 LL |     type Target = dyn Bar<'a>;
-   |     -------------------------- target type is a supertrait of `dyn Foo<'_>`
+   |     ----------- target type is a supertrait of `dyn Foo<'_>`
    |
 note: the lint level is defined here
   --> $DIR/migrate-lint-deny-regions.rs:2:9
diff --git a/tests/ui/traits/trait-upcasting/migrate-lint-different-substs.stderr b/tests/ui/traits/trait-upcasting/migrate-lint-different-substs.stderr
index 86cff5233ff49..a483e98efea1a 100644
--- a/tests/ui/traits/trait-upcasting/migrate-lint-different-substs.stderr
+++ b/tests/ui/traits/trait-upcasting/migrate-lint-different-substs.stderr
@@ -5,7 +5,7 @@ LL | impl<'a> Deref for dyn Foo + 'a {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `dyn Foo` implements `Deref<Target = dyn Bar<u32>>` which conflicts with supertrait `Bar<i32>`
 LL |
 LL |     type Target = dyn Bar<u32> + 'a;
-   |     -------------------------------- target type is a supertrait of `dyn Foo`
+   |     ----------- target type is a supertrait of `dyn Foo`
    |
 note: the lint level is defined here
   --> $DIR/migrate-lint-different-substs.rs:2:9