Auto merge of #143357 - cjgillot:no-assoc-item-kind, r=compiler-errors

Retire hir::*ItemRef.

This information was kept for various places that iterate on HIR to know about trait-items and impl-items.

This PR replaces them by uses of the `associated_items` query that contain pretty much the same information.

This shortens many spans to just `def_span`, which can be easier to read.

32 files changed, 225 insertions, 261 deletions

diff --git a/src/librustdoc/clean/inline.rs b/src/librustdoc/clean/inline.rs
index 37b012d6d0d..9603399f235 100644
--- a/src/librustdoc/clean/inline.rs
+++ b/src/librustdoc/clean/inline.rs
@@ -499,7 +499,7 @@ 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 e6f7aef02c0..e7a1f4d8397 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -2867,7 +2867,7 @@ 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 {
@@ -2910,7 +2910,7 @@ 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 2784d7c761a..9058277d72e 100644
--- a/src/librustdoc/visit_ast.rs
+++ b/src/librustdoc/visit_ast.rs
@@ -469,8 +469,8 @@ 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 8b6bfaebbe5..3a2bad6187c 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 10331b3855b..0a481ddcd12 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 d557a36c7ac..4e948701da4 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 2cb3b32babe..db2fea1aae9 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 68d0cd19c8a..552cd721f4e 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 be887b03ae4..85b40ba7419 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 2d22bb157a9..0d6191f2c97 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 cab7a9fb709..b3c90f364e8 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 b54c289fa7e..e79fcec6e6a 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 900b20aa9cf..03038f0ab49 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 aded31971ce..d32017a8b41 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 caf17c10484..35c9d2fd4eb 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 d4d33029dbd..760ecf07589 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 25c95d23436..329f7193437 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 e266c36b6e7..fa61d0fa11a 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 4b73a4455f5..3b86f1d1f59 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 8eaf65e6306..301b2cd4bf2 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 226e8ff6adb..85fde780e68 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 b36a5d6d502..2de22e4b6a3 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 8bbcb220210..c681806517a 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 a3c35a31c33..87e4b0c5c7d 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 a3c35a31c33..87e4b0c5c7d 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 3fdd706fc62..40505e2a1c4 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 730f12c38a0..d8db2243d41 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 77596ba2394..7f6bddf8005 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 3d903330be8..a7cff238b78 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 dc01a375060..0f700654f7c 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 b2624ac4d26..bf7456d80e2 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 eb6b7c6b0c3..652248e3578 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)]`