diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index 5755ae8a8bc47..9d543563c0f96 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -2845,6 +2845,28 @@ impl Item {
     pub fn span_with_attributes(&self) -> Span {
         self.attrs.iter().fold(self.span, |acc, attr| acc.to(attr.span))
     }
+
+    pub fn opt_generics(&self) -> Option<&Generics> {
+        match &self.kind {
+            ItemKind::ExternCrate(_)
+            | ItemKind::Use(_)
+            | ItemKind::Mod(_, _)
+            | ItemKind::ForeignMod(_)
+            | ItemKind::GlobalAsm(_)
+            | ItemKind::MacCall(_)
+            | ItemKind::MacroDef(_) => None,
+            ItemKind::Static(_) => None,
+            ItemKind::Const(i) => Some(&i.generics),
+            ItemKind::Fn(i) => Some(&i.generics),
+            ItemKind::TyAlias(i) => Some(&i.generics),
+            ItemKind::TraitAlias(generics, _)
+            | ItemKind::Enum(_, generics)
+            | ItemKind::Struct(_, generics)
+            | ItemKind::Union(_, generics) => Some(&generics),
+            ItemKind::Trait(i) => Some(&i.generics),
+            ItemKind::Impl(i) => Some(&i.generics),
+        }
+    }
 }
 
 /// `extern` qualifier on a function item or function type.
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index d9663d50c595c..5c9e43f1e064c 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -453,6 +453,7 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> hir::Crate<'_> {
     tcx.ensure_with_value().output_filenames(());
     tcx.ensure_with_value().early_lint_checks(());
     tcx.ensure_with_value().debugger_visualizers(LOCAL_CRATE);
+    tcx.ensure_with_value().get_lang_items(());
     let (mut resolver, krate) = tcx.resolver_for_lowering(()).steal();
 
     let ast_index = index_crate(&resolver.node_id_to_def_id, &krate);
@@ -765,6 +766,28 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         self.resolver.get_import_res(id).present_items()
     }
 
+    fn make_lang_item_path(
+        &mut self,
+        lang_item: hir::LangItem,
+        span: Span,
+        args: Option<&'hir hir::GenericArgs<'hir>>,
+    ) -> &'hir hir::Path<'hir> {
+        let def_id = self.tcx.require_lang_item(lang_item, Some(span));
+        let def_kind = self.tcx.def_kind(def_id);
+        let res = Res::Def(def_kind, def_id);
+        self.arena.alloc(hir::Path {
+            span,
+            res,
+            segments: self.arena.alloc_from_iter([hir::PathSegment {
+                ident: Ident::new(lang_item.name(), span),
+                hir_id: self.next_id(),
+                res,
+                args,
+                infer_args: false,
+            }]),
+        })
+    }
+
     /// Reuses the span but adds information like the kind of the desugaring and features that are
     /// allowed inside this span.
     fn mark_span_with_reason(
@@ -1976,18 +1999,27 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             CoroutineKind::AsyncGen { .. } => (sym::Item, hir::LangItem::AsyncIterator),
         };
 
-        let future_args = self.arena.alloc(hir::GenericArgs {
+        let bound_args = self.arena.alloc(hir::GenericArgs {
             args: &[],
             bindings: arena_vec![self; self.assoc_ty_binding(assoc_ty_name, opaque_ty_span, output_ty)],
             parenthesized: hir::GenericArgsParentheses::No,
             span_ext: DUMMY_SP,
         });
 
-        hir::GenericBound::LangItemTrait(
-            trait_lang_item,
-            opaque_ty_span,
-            self.next_id(),
-            future_args,
+        hir::GenericBound::Trait(
+            hir::PolyTraitRef {
+                bound_generic_params: &[],
+                trait_ref: hir::TraitRef {
+                    path: self.make_lang_item_path(
+                        trait_lang_item,
+                        opaque_ty_span,
+                        Some(bound_args),
+                    ),
+                    hir_ref_id: self.next_id(),
+                },
+                span: opaque_ty_span,
+            },
+            hir::TraitBoundModifier::None,
         )
     }
 
diff --git a/compiler/rustc_borrowck/src/diagnostics/region_name.rs b/compiler/rustc_borrowck/src/diagnostics/region_name.rs
index 4c3cef2e76315..8441dfaa7df28 100644
--- a/compiler/rustc_borrowck/src/diagnostics/region_name.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/region_name.rs
@@ -788,28 +788,18 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
         };
         let opaque_ty = hir.item(id);
         if let hir::ItemKind::OpaqueTy(hir::OpaqueTy {
-            bounds:
-                [
-                    hir::GenericBound::LangItemTrait(
-                        hir::LangItem::Future,
-                        _,
-                        _,
-                        hir::GenericArgs {
-                            bindings:
-                                [
-                                    hir::TypeBinding {
-                                        ident: Ident { name: sym::Output, .. },
-                                        kind:
-                                            hir::TypeBindingKind::Equality { term: hir::Term::Ty(ty) },
-                                        ..
-                                    },
-                                ],
-                            ..
-                        },
-                    ),
-                ],
+            bounds: [hir::GenericBound::Trait(trait_ref, _)],
             ..
         }) = opaque_ty.kind
+            && let Some(segment) = trait_ref.trait_ref.path.segments.last()
+            && let Some(args) = segment.args
+            && let [
+                hir::TypeBinding {
+                    ident: Ident { name: sym::Output, .. },
+                    kind: hir::TypeBindingKind::Equality { term: hir::Term::Ty(ty) },
+                    ..
+                },
+            ] = args.bindings
         {
             ty
         } else {
diff --git a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
index 40a985cf255d5..015ea10d7216c 100644
--- a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
+++ b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
@@ -578,7 +578,9 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
                     hir_id,
                     no_sanitize_span,
                     "`no_sanitize` will have no effect after inlining",
-                    |lint| lint.span_note(inline_span, "inlining requested here"),
+                    |lint| {
+                        lint.span_note(inline_span, "inlining requested here");
+                    },
                 )
             }
         }
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index 5c252c3f9f2ce..d9401fbd2d142 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -435,8 +435,6 @@ pub enum TraitBoundModifier {
 #[derive(Clone, Copy, Debug, HashStable_Generic)]
 pub enum GenericBound<'hir> {
     Trait(PolyTraitRef<'hir>, TraitBoundModifier),
-    // FIXME(davidtwco): Introduce `PolyTraitRef::LangItem`
-    LangItemTrait(LangItem, Span, HirId, &'hir GenericArgs<'hir>),
     Outlives(&'hir Lifetime),
 }
 
@@ -451,7 +449,6 @@ impl GenericBound<'_> {
     pub fn span(&self) -> Span {
         match self {
             GenericBound::Trait(t, ..) => t.span,
-            GenericBound::LangItemTrait(_, span, ..) => *span,
             GenericBound::Outlives(l) => l.ident.span,
         }
     }
diff --git a/compiler/rustc_hir/src/intravisit.rs b/compiler/rustc_hir/src/intravisit.rs
index 9cf1db166a581..67e058a3219ec 100644
--- a/compiler/rustc_hir/src/intravisit.rs
+++ b/compiler/rustc_hir/src/intravisit.rs
@@ -1075,10 +1075,6 @@ pub fn walk_param_bound<'v, V: Visitor<'v>>(visitor: &mut V, bound: &'v GenericB
         GenericBound::Trait(ref typ, _modifier) => {
             visitor.visit_poly_trait_ref(typ);
         }
-        GenericBound::LangItemTrait(_, _span, hir_id, args) => {
-            visitor.visit_id(hir_id);
-            visitor.visit_generic_args(args);
-        }
         GenericBound::Outlives(ref lifetime) => visitor.visit_lifetime(lifetime),
     }
 }
diff --git a/compiler/rustc_hir/src/target.rs b/compiler/rustc_hir/src/target.rs
index 0d65ddb5642af..8948a03e4a6f8 100644
--- a/compiler/rustc_hir/src/target.rs
+++ b/compiler/rustc_hir/src/target.rs
@@ -67,6 +67,42 @@ impl Display for Target {
 }
 
 impl Target {
+    pub fn is_associated_item(self) -> bool {
+        match self {
+            Target::AssocConst | Target::AssocTy | Target::Method(_) => true,
+            Target::ExternCrate
+            | Target::Use
+            | Target::Static
+            | Target::Const
+            | Target::Fn
+            | Target::Closure
+            | Target::Mod
+            | Target::ForeignMod
+            | Target::GlobalAsm
+            | Target::TyAlias
+            | Target::OpaqueTy
+            | Target::Enum
+            | Target::Variant
+            | Target::Struct
+            | Target::Field
+            | Target::Union
+            | Target::Trait
+            | Target::TraitAlias
+            | Target::Impl
+            | Target::Expression
+            | Target::Statement
+            | Target::Arm
+            | Target::ForeignFn
+            | Target::ForeignStatic
+            | Target::ForeignTy
+            | Target::GenericParam(_)
+            | Target::MacroDef
+            | Target::Param
+            | Target::PatField
+            | Target::ExprField => false,
+        }
+    }
+
     pub fn from_item(item: &Item<'_>) -> Target {
         match item.kind {
             ItemKind::ExternCrate(..) => Target::ExternCrate,
diff --git a/compiler/rustc_hir_analysis/src/astconv/bounds.rs b/compiler/rustc_hir_analysis/src/astconv/bounds.rs
index dfec3c5e829a6..0748644cc0ab9 100644
--- a/compiler/rustc_hir_analysis/src/astconv/bounds.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/bounds.rs
@@ -134,17 +134,6 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
                         only_self_bounds,
                     );
                 }
-                &hir::GenericBound::LangItemTrait(lang_item, span, hir_id, args) => {
-                    self.instantiate_lang_item_trait_ref(
-                        lang_item,
-                        span,
-                        hir_id,
-                        args,
-                        param_ty,
-                        bounds,
-                        only_self_bounds,
-                    );
-                }
                 hir::GenericBound::Outlives(lifetime) => {
                     let region = self.ast_region_to_region(lifetime, None);
                     bounds.push_region_bound(
diff --git a/compiler/rustc_hir_analysis/src/astconv/generics.rs b/compiler/rustc_hir_analysis/src/astconv/generics.rs
index 47fbed45b9132..be73c027fdc86 100644
--- a/compiler/rustc_hir_analysis/src/astconv/generics.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/generics.rs
@@ -661,7 +661,7 @@ pub(crate) fn prohibit_explicit_late_bound_lifetimes(
                 args.args[0].hir_id(),
                 multispan,
                 msg,
-                |lint| lint,
+                |_| {},
             );
         }
 
diff --git a/compiler/rustc_hir_analysis/src/astconv/lint.rs b/compiler/rustc_hir_analysis/src/astconv/lint.rs
index 43d4248ab74e2..9afb04b747028 100644
--- a/compiler/rustc_hir_analysis/src/astconv/lint.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/lint.rs
@@ -122,7 +122,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                             Applicability::MachineApplicable,
                         );
                         self.maybe_lint_blanket_trait_impl(self_ty, lint);
-                        lint
                     },
                 );
             }
diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 2ae9f87f296ba..6f8e80172dd26 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -678,36 +678,57 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         )
     }
 
-    fn instantiate_poly_trait_ref_inner(
+    /// Given a trait bound like `Debug`, applies that trait bound the given self-type to construct
+    /// a full trait reference. The resulting trait reference is returned. This may also generate
+    /// auxiliary bounds, which are added to `bounds`.
+    ///
+    /// Example:
+    ///
+    /// ```ignore (illustrative)
+    /// poly_trait_ref = Iterator<Item = u32>
+    /// self_ty = Foo
+    /// ```
+    ///
+    /// this would return `Foo: Iterator` and add `<Foo as Iterator>::Item = u32` into `bounds`.
+    ///
+    /// **A note on binders:** against our usual convention, there is an implied binder around
+    /// the `self_ty` and `poly_trait_ref` parameters here. So they may reference bound regions.
+    /// If for example you had `for<'a> Foo<'a>: Bar<'a>`, then the `self_ty` would be `Foo<'a>`
+    /// where `'a` is a bound region at depth 0. Similarly, the `poly_trait_ref` would be
+    /// `Bar<'a>`. The returned poly-trait-ref will have this binder instantiated explicitly,
+    /// however.
+    #[instrument(level = "debug", skip(self, span, constness, bounds, speculative))]
+    pub(crate) fn instantiate_poly_trait_ref(
         &self,
-        hir_id: hir::HirId,
+        trait_ref: &hir::TraitRef<'_>,
         span: Span,
-        binding_span: Option<Span>,
         constness: ty::BoundConstness,
         polarity: ty::ImplPolarity,
+        self_ty: Ty<'tcx>,
         bounds: &mut Bounds<'tcx>,
         speculative: bool,
-        trait_ref_span: Span,
-        trait_def_id: DefId,
-        trait_segment: &hir::PathSegment<'_>,
-        args: &GenericArgs<'_>,
-        infer_args: bool,
-        self_ty: Ty<'tcx>,
         only_self_bounds: OnlySelfBounds,
     ) -> GenericArgCountResult {
+        let trait_def_id = trait_ref.trait_def_id().unwrap_or_else(|| FatalError.raise());
+        let trait_segment = trait_ref.path.segments.last().unwrap();
+        let args = trait_segment.args();
+
+        self.prohibit_generics(trait_ref.path.segments.split_last().unwrap().1.iter(), |_| {});
+        self.complain_about_internal_fn_trait(span, trait_def_id, trait_segment, false);
+
         let (generic_args, arg_count) = self.create_args_for_ast_path(
-            trait_ref_span,
+            trait_ref.path.span,
             trait_def_id,
             &[],
             trait_segment,
             args,
-            infer_args,
+            trait_segment.infer_args,
             Some(self_ty),
             constness,
         );
 
         let tcx = self.tcx();
-        let bound_vars = tcx.late_bound_vars(hir_id);
+        let bound_vars = tcx.late_bound_vars(trait_ref.hir_ref_id);
         debug!(?bound_vars);
 
         let assoc_bindings = self.create_assoc_bindings_for_generic_args(args);
@@ -735,13 +756,13 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
 
             // Specify type to assert that error was already reported in `Err` case.
             let _: Result<_, ErrorGuaranteed> = self.add_predicates_for_ast_type_binding(
-                hir_id,
+                trait_ref.hir_ref_id,
                 poly_trait_ref,
                 binding,
                 bounds,
                 speculative,
                 &mut dup_bindings,
-                binding_span.unwrap_or(binding.span),
+                binding.span,
                 constness,
                 only_self_bounds,
                 polarity,
@@ -752,102 +773,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         arg_count
     }
 
-    /// Given a trait bound like `Debug`, applies that trait bound the given self-type to construct
-    /// a full trait reference. The resulting trait reference is returned. This may also generate
-    /// auxiliary bounds, which are added to `bounds`.
-    ///
-    /// Example:
-    ///
-    /// ```ignore (illustrative)
-    /// poly_trait_ref = Iterator<Item = u32>
-    /// self_ty = Foo
-    /// ```
-    ///
-    /// this would return `Foo: Iterator` and add `<Foo as Iterator>::Item = u32` into `bounds`.
-    ///
-    /// **A note on binders:** against our usual convention, there is an implied bounder around
-    /// the `self_ty` and `poly_trait_ref` parameters here. So they may reference bound regions.
-    /// If for example you had `for<'a> Foo<'a>: Bar<'a>`, then the `self_ty` would be `Foo<'a>`
-    /// where `'a` is a bound region at depth 0. Similarly, the `poly_trait_ref` would be
-    /// `Bar<'a>`. The returned poly-trait-ref will have this binder instantiated explicitly,
-    /// however.
-    #[instrument(level = "debug", skip(self, span, constness, bounds, speculative))]
-    pub(crate) fn instantiate_poly_trait_ref(
-        &self,
-        trait_ref: &hir::TraitRef<'_>,
-        span: Span,
-        constness: ty::BoundConstness,
-        polarity: ty::ImplPolarity,
-        self_ty: Ty<'tcx>,
-        bounds: &mut Bounds<'tcx>,
-        speculative: bool,
-        only_self_bounds: OnlySelfBounds,
-    ) -> GenericArgCountResult {
-        let hir_id = trait_ref.hir_ref_id;
-        let binding_span = None;
-        let trait_ref_span = trait_ref.path.span;
-        let trait_def_id = trait_ref.trait_def_id().unwrap_or_else(|| FatalError.raise());
-        let trait_segment = trait_ref.path.segments.last().unwrap();
-        let args = trait_segment.args();
-        let infer_args = trait_segment.infer_args;
-
-        self.prohibit_generics(trait_ref.path.segments.split_last().unwrap().1.iter(), |_| {});
-        self.complain_about_internal_fn_trait(span, trait_def_id, trait_segment, false);
-
-        self.instantiate_poly_trait_ref_inner(
-            hir_id,
-            span,
-            binding_span,
-            constness,
-            polarity,
-            bounds,
-            speculative,
-            trait_ref_span,
-            trait_def_id,
-            trait_segment,
-            args,
-            infer_args,
-            self_ty,
-            only_self_bounds,
-        )
-    }
-
-    pub(crate) fn instantiate_lang_item_trait_ref(
-        &self,
-        lang_item: hir::LangItem,
-        span: Span,
-        hir_id: hir::HirId,
-        args: &GenericArgs<'_>,
-        self_ty: Ty<'tcx>,
-        bounds: &mut Bounds<'tcx>,
-        only_self_bounds: OnlySelfBounds,
-    ) {
-        let binding_span = Some(span);
-        let constness = ty::BoundConstness::NotConst;
-        let speculative = false;
-        let trait_ref_span = span;
-        let trait_def_id = self.tcx().require_lang_item(lang_item, Some(span));
-        let trait_segment = &hir::PathSegment::invalid();
-        let infer_args = false;
-
-        self.instantiate_poly_trait_ref_inner(
-            hir_id,
-            span,
-            binding_span,
-            constness,
-            ty::ImplPolarity::Positive,
-            bounds,
-            speculative,
-            trait_ref_span,
-            trait_def_id,
-            trait_segment,
-            args,
-            infer_args,
-            self_ty,
-            only_self_bounds,
-        );
-    }
-
     fn ast_path_to_mono_trait_ref(
         &self,
         span: Span,
@@ -1509,8 +1434,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                         format!("<{} as {}>::{}", qself_ty, tcx.item_name(trait_did), assoc_ident),
                         Applicability::MachineApplicable,
                     );
-
-                    lint
                 },
             );
         }
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index e6245e4d0b146..8413a1cc0dba9 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -51,7 +51,7 @@ pub fn check_abi(tcx: TyCtxt<'_>, hir_id: hir::HirId, span: Span, abi: Abi) {
                 hir_id,
                 span,
                 "use of calling convention not supported on this target",
-                |lint| lint,
+                |_| {},
             );
         }
     }
@@ -190,7 +190,7 @@ fn check_static_inhabited(tcx: TyCtxt<'_>, def_id: LocalDefId) {
             "static of uninhabited type",
             |lint| {
                 lint
-                .note("uninhabited statics cannot be initialized, and any access would be an immediate error")
+                .note("uninhabited statics cannot be initialized, and any access would be an immediate error");
             },
         );
     }
@@ -1093,7 +1093,7 @@ pub(super) fn check_transparent<'tcx>(tcx: TyCtxt<'tcx>, adt: ty::AdtDef<'tcx>)
                             "this {descr} contains `{field_ty}`, which {note}, \
                                 and makes it not a breaking change to become \
                                 non-zero-sized in the future."
-                        ))
+                        ));
                     },
                 )
             } else {
diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
index 4705d9350b0a3..18d9963aaa46b 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
@@ -574,7 +574,6 @@ fn emit_implied_wf_lint<'tcx>(
                     Applicability::MaybeIncorrect,
                 );
             }
-            lint
         },
     );
 }
diff --git a/compiler/rustc_hir_analysis/src/check/intrinsicck.rs b/compiler/rustc_hir_analysis/src/check/intrinsicck.rs
index 7c9624206e539..d86ebc2c9c323 100644
--- a/compiler/rustc_hir_analysis/src/check/intrinsicck.rs
+++ b/compiler/rustc_hir_analysis/src/check/intrinsicck.rs
@@ -276,7 +276,6 @@ impl<'a, 'tcx> InlineAsmCtxt<'a, 'tcx> {
                         lint.help(format!(
                             "or use `{{{idx}:{default_modifier}}}` to keep the default formatting of `{default_result}`",
                         ));
-                        lint
                     },
                 );
             }
diff --git a/compiler/rustc_hir_analysis/src/check_unused.rs b/compiler/rustc_hir_analysis/src/check_unused.rs
index 9ad73eeffc6ae..36cb8f7a20228 100644
--- a/compiler/rustc_hir_analysis/src/check_unused.rs
+++ b/compiler/rustc_hir_analysis/src/check_unused.rs
@@ -45,7 +45,7 @@ fn check_unused_traits(tcx: TyCtxt<'_>, (): ()) {
             item.hir_id(),
             path.span,
             msg,
-            |lint| lint,
+            |_| {},
         );
     }
 }
diff --git a/compiler/rustc_hir_analysis/src/coherence/orphan.rs b/compiler/rustc_hir_analysis/src/coherence/orphan.rs
index 451004576292a..88128d22a3db2 100644
--- a/compiler/rustc_hir_analysis/src/coherence/orphan.rs
+++ b/compiler/rustc_hir_analysis/src/coherence/orphan.rs
@@ -522,7 +522,7 @@ fn lint_auto_trait_impl<'tcx>(
                 format!(
                     "try using the same sequence of generic parameters as the {self_descr} definition",
                 ),
-            )
+            );
         },
     );
 }
diff --git a/compiler/rustc_hir_analysis/src/collect/generics_of.rs b/compiler/rustc_hir_analysis/src/collect/generics_of.rs
index c1c2bb62c66e0..3ee2822edd8eb 100644
--- a/compiler/rustc_hir_analysis/src/collect/generics_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/generics_of.rs
@@ -279,7 +279,7 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
                             param.hir_id,
                             param.span,
                             TYPE_DEFAULT_NOT_ALLOWED,
-                            |lint| lint,
+                            |_| {},
                         );
                     }
                     Defaults::Deny => {
diff --git a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
index 5769fc5fe6408..a1aac4df932e1 100644
--- a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
+++ b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
@@ -925,7 +925,7 @@ impl<'a, 'tcx> Visitor<'tcx> for BoundVarContext<'a, 'tcx> {
                                     "you can use the `'static` lifetime directly, in place of `{}`",
                                     lifetime.ident,
                                 );
-                                lint.help(help)
+                                lint.help(help);
                             },
                         );
                     }
@@ -938,32 +938,6 @@ impl<'a, 'tcx> Visitor<'tcx> for BoundVarContext<'a, 'tcx> {
         }
     }
 
-    fn visit_param_bound(&mut self, bound: &'tcx hir::GenericBound<'tcx>) {
-        match bound {
-            hir::GenericBound::LangItemTrait(_, _, hir_id, _) => {
-                // FIXME(jackh726): This is pretty weird. `LangItemTrait` doesn't go
-                // through the regular poly trait ref code, so we don't get another
-                // chance to introduce a binder. For now, I'm keeping the existing logic
-                // of "if there isn't a Binder scope above us, add one", but I
-                // imagine there's a better way to go about this.
-                let (binders, scope_type) = self.poly_trait_ref_binder_info();
-
-                self.record_late_bound_vars(*hir_id, binders);
-                let scope = Scope::Binder {
-                    hir_id: *hir_id,
-                    bound_vars: FxIndexMap::default(),
-                    s: self.scope,
-                    scope_type,
-                    where_bound_origin: None,
-                };
-                self.with(scope, |this| {
-                    intravisit::walk_param_bound(this, bound);
-                });
-            }
-            _ => intravisit::walk_param_bound(self, bound),
-        }
-    }
-
     fn visit_poly_trait_ref(&mut self, trait_ref: &'tcx hir::PolyTraitRef<'tcx>) {
         self.visit_poly_trait_ref_inner(trait_ref, NonLifetimeBinderAllowed::Allow);
     }
diff --git a/compiler/rustc_hir_pretty/src/lib.rs b/compiler/rustc_hir_pretty/src/lib.rs
index 82e687135eb29..21a50b94a37a8 100644
--- a/compiler/rustc_hir_pretty/src/lib.rs
+++ b/compiler/rustc_hir_pretty/src/lib.rs
@@ -2084,11 +2084,6 @@ impl<'a> State<'a> {
                     }
                     self.print_poly_trait_ref(tref);
                 }
-                GenericBound::LangItemTrait(lang_item, span, ..) => {
-                    self.word("#[lang = \"");
-                    self.print_ident(Ident::new(lang_item.name(), *span));
-                    self.word("\"]");
-                }
                 GenericBound::Outlives(lt) => {
                     self.print_lifetime(lt);
                 }
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
index 7744f75121eec..3bee42eb89cf9 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
@@ -72,7 +72,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             orig_span,
                             custom_note
                                 .unwrap_or("any code following this expression is unreachable"),
-                        )
+                        );
                     },
                 )
             }
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
index 1650aaeb4957a..668e547571f69 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
@@ -825,9 +825,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     && let hir::Node::Item(hir::Item {
                         kind: hir::ItemKind::OpaqueTy(op_ty), ..
                     }) = self.tcx.hir_node(item_id.hir_id())
-                    && let [
-                        hir::GenericBound::LangItemTrait(hir::LangItem::Future, _, _, generic_args),
-                    ] = op_ty.bounds
+                    && let [hir::GenericBound::Trait(trait_ref, _)] = op_ty.bounds
+                    && let Some(hir::PathSegment { args: Some(generic_args), .. }) =
+                        trait_ref.trait_ref.path.segments.last()
                     && let hir::GenericArgs { bindings: [ty_binding], .. } = generic_args
                     && let hir::TypeBindingKind::Equality { term: hir::Term::Ty(term) } =
                         ty_binding.kind
diff --git a/compiler/rustc_hir_typeck/src/method/prelude2021.rs b/compiler/rustc_hir_typeck/src/method/prelude2021.rs
index 3f1dca5b1deaa..43d258de6ca7a 100644
--- a/compiler/rustc_hir_typeck/src/method/prelude2021.rs
+++ b/compiler/rustc_hir_typeck/src/method/prelude2021.rs
@@ -122,8 +122,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             format!("disambiguate the method call with `({self_adjusted})`",),
                         );
                     }
-
-                    lint
                 },
             );
         } else {
@@ -187,8 +185,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             ),
                         );
                     }
-
-                    lint
                 },
             );
         }
@@ -307,8 +303,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     format!("<{} as {}>::{}", self_ty_name, trait_name, method_name.name,),
                     Applicability::MachineApplicable,
                 );
-
-                lint
             },
         );
     }
diff --git a/compiler/rustc_hir_typeck/src/method/probe.rs b/compiler/rustc_hir_typeck/src/method/probe.rs
index 4243bce377fb4..bbcc04af6f3ee 100644
--- a/compiler/rustc_hir_typeck/src/method/probe.rs
+++ b/compiler/rustc_hir_typeck/src/method/probe.rs
@@ -445,7 +445,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         scope_expr_id,
                         span,
                         "type annotations needed",
-                        |lint| lint,
+                        |_| {},
                     );
                 }
             } else {
@@ -1427,8 +1427,6 @@ impl<'tcx> Pick<'tcx> {
                         ));
                     }
                 }
-
-                lint
             },
         );
     }
diff --git a/compiler/rustc_hir_typeck/src/pat.rs b/compiler/rustc_hir_typeck/src/pat.rs
index be21fd5f0a630..56a420fab4fef 100644
--- a/compiler/rustc_hir_typeck/src/pat.rs
+++ b/compiler/rustc_hir_typeck/src/pat.rs
@@ -1849,8 +1849,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         lint.note(format!(
             "the pattern is of type `{ty}` and the `non_exhaustive_omitted_patterns` attribute was found",
         ));
-
-        lint
     });
     }
 
diff --git a/compiler/rustc_hir_typeck/src/upvar.rs b/compiler/rustc_hir_typeck/src/upvar.rs
index 998ee339ae2c4..69d6fb8e2eab7 100644
--- a/compiler/rustc_hir_typeck/src/upvar.rs
+++ b/compiler/rustc_hir_typeck/src/upvar.rs
@@ -912,8 +912,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             Applicability::HasPlaceholders
                         );
                     }
-
-                    lint
                 },
             );
         }
diff --git a/compiler/rustc_infer/src/infer/error_reporting/suggest.rs b/compiler/rustc_infer/src/infer/error_reporting/suggest.rs
index b762778122ba4..bbe07b8ed72b2 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/suggest.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/suggest.rs
@@ -668,26 +668,16 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     (
                         hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds: last_bounds, .. }),
                         hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds: exp_bounds, .. }),
-                    ) if std::iter::zip(*last_bounds, *exp_bounds).all(|(left, right)| {
-                        match (left, right) {
-                            (
-                                hir::GenericBound::Trait(tl, ml),
-                                hir::GenericBound::Trait(tr, mr),
-                            ) if tl.trait_ref.trait_def_id() == tr.trait_ref.trait_def_id()
+                    ) if std::iter::zip(*last_bounds, *exp_bounds).all(|(left, right)| match (
+                        left, right,
+                    ) {
+                        (hir::GenericBound::Trait(tl, ml), hir::GenericBound::Trait(tr, mr))
+                            if tl.trait_ref.trait_def_id() == tr.trait_ref.trait_def_id()
                                 && ml == mr =>
-                            {
-                                true
-                            }
-                            (
-                                hir::GenericBound::LangItemTrait(langl, _, _, argsl),
-                                hir::GenericBound::LangItemTrait(langr, _, _, argsr),
-                            ) if langl == langr => {
-                                // FIXME: consider the bounds!
-                                debug!("{:?} {:?}", argsl, argsr);
-                                true
-                            }
-                            _ => false,
+                        {
+                            true
                         }
+                        _ => false,
                     }) =>
                     {
                         StatementAsExpression::NeedsBoxing
diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 32eb67ba3a114..045ff38c0568c 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -2800,7 +2800,7 @@ impl<'tcx> LateLintPass<'tcx> for NamedAsmLabels {
                             NAMED_ASM_LABELS,
                             Some(target_spans),
                             fluent::lint_builtin_asm_labels,
-                            |lint| lint,
+                            |_| {},
                             BuiltinLintDiagnostics::NamedAsmLabel(
                                 "only local labels of the form `<number>:` should be used in inline asm"
                                     .to_string(),
diff --git a/compiler/rustc_lint/src/context.rs b/compiler/rustc_lint/src/context.rs
index 0911fa70f9725..c7a9d5e80aca6 100644
--- a/compiler/rustc_lint/src/context.rs
+++ b/compiler/rustc_lint/src/context.rs
@@ -520,9 +520,6 @@ pub trait LintContext {
     /// Emit a lint at the appropriate level, with an optional associated span and an existing
     /// diagnostic.
     ///
-    /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed
-    /// explanation.
-    ///
     /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature
     #[rustc_lint_diagnostics]
     fn lookup_with_diagnostics(
@@ -530,9 +527,7 @@ pub trait LintContext {
         lint: &'static Lint,
         span: Option<impl Into<MultiSpan>>,
         msg: impl Into<DiagnosticMessage>,
-        decorate: impl for<'a, 'b> FnOnce(
-            &'b mut DiagnosticBuilder<'a, ()>,
-        ) -> &'b mut DiagnosticBuilder<'a, ()>,
+        decorate: impl for<'a, 'b> FnOnce(&'b mut DiagnosticBuilder<'a, ()>),
         diagnostic: BuiltinLintDiagnostics,
     ) {
         // We first generate a blank diagnostic.
@@ -986,8 +981,6 @@ pub trait LintContext {
     // set the span in their `decorate` function (preferably using set_span).
     /// Emit a lint at the appropriate level, with an optional associated span.
     ///
-    /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation.
-    ///
     /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature
     #[rustc_lint_diagnostics]
     fn lookup<S: Into<MultiSpan>>(
@@ -995,9 +988,7 @@ pub trait LintContext {
         lint: &'static Lint,
         span: Option<S>,
         msg: impl Into<DiagnosticMessage>,
-        decorate: impl for<'a, 'b> FnOnce(
-            &'b mut DiagnosticBuilder<'a, ()>,
-        ) -> &'b mut DiagnosticBuilder<'a, ()>,
+        decorate: impl for<'a, 'b> FnOnce(&'b mut DiagnosticBuilder<'a, ()>),
     );
 
     /// Emit a lint at `span` from a lint struct (some type that implements `DecorateLint`,
@@ -1008,13 +999,13 @@ pub trait LintContext {
         span: S,
         decorator: impl for<'a> DecorateLint<'a, ()>,
     ) {
-        self.lookup(lint, Some(span), decorator.msg(), |diag| decorator.decorate_lint(diag));
+        self.lookup(lint, Some(span), decorator.msg(), |diag| {
+            decorator.decorate_lint(diag);
+        });
     }
 
     /// Emit a lint at the appropriate level, with an associated span.
     ///
-    /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation.
-    ///
     /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature
     #[rustc_lint_diagnostics]
     fn struct_span_lint<S: Into<MultiSpan>>(
@@ -1022,9 +1013,7 @@ pub trait LintContext {
         lint: &'static Lint,
         span: S,
         msg: impl Into<DiagnosticMessage>,
-        decorate: impl for<'a, 'b> FnOnce(
-            &'b mut DiagnosticBuilder<'a, ()>,
-        ) -> &'b mut DiagnosticBuilder<'a, ()>,
+        decorate: impl for<'a, 'b> FnOnce(&'b mut DiagnosticBuilder<'a, ()>),
     ) {
         self.lookup(lint, Some(span), msg, decorate);
     }
@@ -1033,23 +1022,19 @@ pub trait LintContext {
     /// generated by `#[derive(LintDiagnostic)]`).
     fn emit_lint(&self, lint: &'static Lint, decorator: impl for<'a> DecorateLint<'a, ()>) {
         self.lookup(lint, None as Option<Span>, decorator.msg(), |diag| {
-            decorator.decorate_lint(diag)
+            decorator.decorate_lint(diag);
         });
     }
 
     /// Emit a lint at the appropriate level, with no associated span.
     ///
-    /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation.
-    ///
     /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature
     #[rustc_lint_diagnostics]
     fn lint(
         &self,
         lint: &'static Lint,
         msg: impl Into<DiagnosticMessage>,
-        decorate: impl for<'a, 'b> FnOnce(
-            &'b mut DiagnosticBuilder<'a, ()>,
-        ) -> &'b mut DiagnosticBuilder<'a, ()>,
+        decorate: impl for<'a, 'b> FnOnce(&'b mut DiagnosticBuilder<'a, ()>),
     ) {
         self.lookup(lint, None as Option<Span>, msg, decorate);
     }
@@ -1113,9 +1098,7 @@ impl<'tcx> LintContext for LateContext<'tcx> {
         lint: &'static Lint,
         span: Option<S>,
         msg: impl Into<DiagnosticMessage>,
-        decorate: impl for<'a, 'b> FnOnce(
-            &'b mut DiagnosticBuilder<'a, ()>,
-        ) -> &'b mut DiagnosticBuilder<'a, ()>,
+        decorate: impl for<'a, 'b> FnOnce(&'b mut DiagnosticBuilder<'a, ()>),
     ) {
         let hir_id = self.last_node_with_lint_attrs;
 
@@ -1142,9 +1125,7 @@ impl LintContext for EarlyContext<'_> {
         lint: &'static Lint,
         span: Option<S>,
         msg: impl Into<DiagnosticMessage>,
-        decorate: impl for<'a, 'b> FnOnce(
-            &'b mut DiagnosticBuilder<'a, ()>,
-        ) -> &'b mut DiagnosticBuilder<'a, ()>,
+        decorate: impl for<'a, 'b> FnOnce(&'b mut DiagnosticBuilder<'a, ()>),
     ) {
         self.builder.struct_lint(lint, span.map(|s| s.into()), msg, decorate)
     }
diff --git a/compiler/rustc_lint/src/early.rs b/compiler/rustc_lint/src/early.rs
index 4c7f9eeff8c28..b9add9e9f0657 100644
--- a/compiler/rustc_lint/src/early.rs
+++ b/compiler/rustc_lint/src/early.rs
@@ -45,13 +45,7 @@ impl<'a, T: EarlyLintPass> EarlyContextAndPass<'a, T> {
     fn inlined_check_id(&mut self, id: ast::NodeId) {
         for early_lint in self.context.buffered.take(id) {
             let BufferedEarlyLint { span, msg, node_id: _, lint_id, diagnostic } = early_lint;
-            self.context.lookup_with_diagnostics(
-                lint_id.lint,
-                Some(span),
-                msg,
-                |lint| lint,
-                diagnostic,
-            );
+            self.context.lookup_with_diagnostics(lint_id.lint, Some(span), msg, |_| {}, diagnostic);
         }
     }
 
diff --git a/compiler/rustc_lint/src/levels.rs b/compiler/rustc_lint/src/levels.rs
index c1d4ed37627f2..8c8ff3fc65064 100644
--- a/compiler/rustc_lint/src/levels.rs
+++ b/compiler/rustc_lint/src/levels.rs
@@ -1077,7 +1077,6 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
                             GateIssue::Language,
                             lint_from_cli,
                         );
-                        lint
                     },
                 );
                 return false;
@@ -1094,8 +1093,6 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
     /// Used to emit a lint-related diagnostic based on the current state of
     /// this lint context.
     ///
-    /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation.
-    ///
     /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature
     #[rustc_lint_diagnostics]
     #[track_caller]
@@ -1104,9 +1101,7 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
         lint: &'static Lint,
         span: Option<MultiSpan>,
         msg: impl Into<DiagnosticMessage>,
-        decorate: impl for<'a, 'b> FnOnce(
-            &'b mut DiagnosticBuilder<'a, ()>,
-        ) -> &'b mut DiagnosticBuilder<'a, ()>,
+        decorate: impl for<'a, 'b> FnOnce(&'b mut DiagnosticBuilder<'a, ()>),
     ) {
         let (level, src) = self.lint_level(lint);
         struct_lint_level(self.sess, lint, level, src, span, msg, decorate)
@@ -1121,7 +1116,7 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
     ) {
         let (level, src) = self.lint_level(lint);
         struct_lint_level(self.sess, lint, level, src, Some(span), decorate.msg(), |lint| {
-            decorate.decorate_lint(lint)
+            decorate.decorate_lint(lint);
         });
     }
 
@@ -1129,7 +1124,7 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
     pub fn emit_lint(&self, lint: &'static Lint, decorate: impl for<'a> DecorateLint<'a, ()>) {
         let (level, src) = self.lint_level(lint);
         struct_lint_level(self.sess, lint, level, src, None, decorate.msg(), |lint| {
-            decorate.decorate_lint(lint)
+            decorate.decorate_lint(lint);
         });
     }
 }
diff --git a/compiler/rustc_lint/src/non_fmt_panic.rs b/compiler/rustc_lint/src/non_fmt_panic.rs
index f0e415492ae96..9fcd70ba0b569 100644
--- a/compiler/rustc_lint/src/non_fmt_panic.rs
+++ b/compiler/rustc_lint/src/non_fmt_panic.rs
@@ -126,7 +126,7 @@ fn check_panic<'tcx>(cx: &LateContext<'tcx>, f: &'tcx hir::Expr<'tcx>, arg: &'tc
         lint.note(fluent::lint_more_info_note);
         if !is_arg_inside_call(arg_span, span) {
             // No clue where this argument is coming from.
-            return lint;
+            return;
         }
         if arg_macro.is_some_and(|id| cx.tcx.is_diagnostic_item(sym::format_macro, id)) {
             // A case of `panic!(format!(..))`.
@@ -207,7 +207,6 @@ fn check_panic<'tcx>(cx: &LateContext<'tcx>, f: &'tcx hir::Expr<'tcx>, arg: &'tc
                 }
             }
         }
-        lint
     });
 }
 
diff --git a/compiler/rustc_middle/src/lint.rs b/compiler/rustc_middle/src/lint.rs
index eada116f89638..4c4f38d1ad8cf 100644
--- a/compiler/rustc_middle/src/lint.rs
+++ b/compiler/rustc_middle/src/lint.rs
@@ -253,29 +253,10 @@ pub fn explain_lint_level_source(
 /// - [`TyCtxt::struct_lint_node`]
 /// - `LintContext::lookup`
 ///
-/// ## `decorate` signature
+/// ## `decorate`
 ///
-/// The return value of `decorate` is ignored by this function. So what is the
-/// point of returning `&'b mut DiagnosticBuilder<'a, ()>`?
-///
-/// There are 2 reasons for this signature.
-///
-/// First of all, it prevents accidental use of `.emit()` -- it's clear that the
-/// builder will be later used and shouldn't be emitted right away (this is
-/// especially important because the old API expected you to call `.emit()` in
-/// the closure).
-///
-/// Second of all, it makes the most common case of adding just a single label
-/// /suggestion much nicer, since [`DiagnosticBuilder`] methods return
-/// `&mut DiagnosticBuilder`, you can just chain methods, without needed
-/// awkward `{ ...; }`:
-/// ```ignore pseudo-code
-/// struct_lint_level(
-///     ...,
-///     |lint| lint.span_label(sp, "lbl")
-///     //          ^^^^^^^^^^^^^^^^^^^^^ returns `&mut DiagnosticBuilder` by default
-/// )
-/// ```
+/// It is not intended to call `emit`/`cancel` on the `DiagnosticBuilder` passed
+/// in the `decorate` callback.
 #[track_caller]
 pub fn struct_lint_level(
     sess: &Session,
@@ -284,9 +265,7 @@ pub fn struct_lint_level(
     src: LintLevelSource,
     span: Option<MultiSpan>,
     msg: impl Into<DiagnosticMessage>,
-    decorate: impl for<'a, 'b> FnOnce(
-        &'b mut DiagnosticBuilder<'a, ()>,
-    ) -> &'b mut DiagnosticBuilder<'a, ()>,
+    decorate: impl for<'a, 'b> FnOnce(&'b mut DiagnosticBuilder<'a, ()>),
 ) {
     // Avoid codegen bloat from monomorphization by immediately doing dyn dispatch of `decorate` to
     // the "real" work.
@@ -298,12 +277,7 @@ pub fn struct_lint_level(
         src: LintLevelSource,
         span: Option<MultiSpan>,
         msg: impl Into<DiagnosticMessage>,
-        decorate: Box<
-            dyn '_
-                + for<'a, 'b> FnOnce(
-                    &'b mut DiagnosticBuilder<'a, ()>,
-                ) -> &'b mut DiagnosticBuilder<'a, ()>,
-        >,
+        decorate: Box<dyn '_ + for<'a, 'b> FnOnce(&'b mut DiagnosticBuilder<'a, ()>)>,
     ) {
         // Check for future incompatibility lints and issue a stronger warning.
         let future_incompatible = lint.future_incompatible;
diff --git a/compiler/rustc_middle/src/middle/stability.rs b/compiler/rustc_middle/src/middle/stability.rs
index 564a1fad14dad..0cba6d5b52a8f 100644
--- a/compiler/rustc_middle/src/middle/stability.rs
+++ b/compiler/rustc_middle/src/middle/stability.rs
@@ -223,7 +223,6 @@ fn late_report_deprecation(
             let kind = tcx.def_descr(def_id);
             deprecation_suggestion(diag, kind, suggestion, method_span);
         }
-        diag
     });
 }
 
@@ -587,7 +586,7 @@ impl<'tcx> TyCtxt<'tcx> {
         unmarked: impl FnOnce(Span, DefId),
     ) -> bool {
         let soft_handler = |lint, span, msg: String| {
-            self.struct_span_lint_hir(lint, id.unwrap_or(hir::CRATE_HIR_ID), span, msg, |lint| lint)
+            self.struct_span_lint_hir(lint, id.unwrap_or(hir::CRATE_HIR_ID), span, msg, |_| {})
         };
         let eval_result =
             self.eval_stability_allow_unstable(def_id, id, span, method_span, allow_unstable);
diff --git a/compiler/rustc_middle/src/mir/interpret/queries.rs b/compiler/rustc_middle/src/mir/interpret/queries.rs
index 34068a9da37e8..092b59deeff36 100644
--- a/compiler/rustc_middle/src/mir/interpret/queries.rs
+++ b/compiler/rustc_middle/src/mir/interpret/queries.rs
@@ -113,7 +113,7 @@ impl<'tcx> TyCtxt<'tcx> {
                                 self.local_def_id_to_hir_id(local_def_id),
                                 self.def_span(ct.def),
                                 "cannot use constants which depend on generic parameters in types",
-                                |err| err,
+                                |_| {},
                             )
                         }
                     }
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 5e61847a37a0e..6a6ed59fabfa9 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -2030,14 +2030,12 @@ impl<'tcx> TyCtxt<'tcx> {
         let msg = decorator.msg();
         let (level, src) = self.lint_level_at_node(lint, hir_id);
         struct_lint_level(self.sess, lint, level, src, Some(span.into()), msg, |diag| {
-            decorator.decorate_lint(diag)
+            decorator.decorate_lint(diag);
         })
     }
 
     /// Emit a lint at the appropriate level for a hir node, with an associated span.
     ///
-    /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation.
-    ///
     /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature
     #[rustc_lint_diagnostics]
     #[track_caller]
@@ -2047,9 +2045,7 @@ impl<'tcx> TyCtxt<'tcx> {
         hir_id: HirId,
         span: impl Into<MultiSpan>,
         msg: impl Into<DiagnosticMessage>,
-        decorate: impl for<'a, 'b> FnOnce(
-            &'b mut DiagnosticBuilder<'a, ()>,
-        ) -> &'b mut DiagnosticBuilder<'a, ()>,
+        decorate: impl for<'a, 'b> FnOnce(&'b mut DiagnosticBuilder<'a, ()>),
     ) {
         let (level, src) = self.lint_level_at_node(lint, hir_id);
         struct_lint_level(self.sess, lint, level, src, Some(span.into()), msg, decorate);
@@ -2064,13 +2060,13 @@ impl<'tcx> TyCtxt<'tcx> {
         id: HirId,
         decorator: impl for<'a> DecorateLint<'a, ()>,
     ) {
-        self.struct_lint_node(lint, id, decorator.msg(), |diag| decorator.decorate_lint(diag))
+        self.struct_lint_node(lint, id, decorator.msg(), |diag| {
+            decorator.decorate_lint(diag);
+        })
     }
 
     /// Emit a lint at the appropriate level for a hir node.
     ///
-    /// Return value of the `decorate` closure is ignored, see [`struct_lint_level`] for a detailed explanation.
-    ///
     /// [`struct_lint_level`]: rustc_middle::lint::struct_lint_level#decorate-signature
     #[rustc_lint_diagnostics]
     #[track_caller]
@@ -2079,9 +2075,7 @@ impl<'tcx> TyCtxt<'tcx> {
         lint: &'static Lint,
         id: HirId,
         msg: impl Into<DiagnosticMessage>,
-        decorate: impl for<'a, 'b> FnOnce(
-            &'b mut DiagnosticBuilder<'a, ()>,
-        ) -> &'b mut DiagnosticBuilder<'a, ()>,
+        decorate: impl for<'a, 'b> FnOnce(&'b mut DiagnosticBuilder<'a, ()>),
     ) {
         let (level, src) = self.lint_level_at_node(lint, id);
         struct_lint_level(self.sess, lint, level, src, None, msg, decorate);
diff --git a/compiler/rustc_passes/src/hir_stats.rs b/compiler/rustc_passes/src/hir_stats.rs
index 85969b72d2397..c2392620cb285 100644
--- a/compiler/rustc_passes/src/hir_stats.rs
+++ b/compiler/rustc_passes/src/hir_stats.rs
@@ -429,7 +429,7 @@ impl<'v> hir_visit::Visitor<'v> for StatCollector<'v> {
     fn visit_param_bound(&mut self, b: &'v hir::GenericBound<'v>) {
         record_variants!(
             (self, b, b, Id::None, hir, GenericBound, GenericBound),
-            [Trait, LangItemTrait, Outlives]
+            [Trait, Outlives]
         );
         hir_visit::walk_param_bound(self, b)
     }
diff --git a/compiler/rustc_passes/src/lang_items.rs b/compiler/rustc_passes/src/lang_items.rs
index 83b7d8d71bc85..6d14a14096d0b 100644
--- a/compiler/rustc_passes/src/lang_items.rs
+++ b/compiler/rustc_passes/src/lang_items.rs
@@ -7,18 +7,18 @@
 //! * Traits that represent operators; e.g., `Add`, `Sub`, `Index`.
 //! * Functions called by the compiler itself.
 
-use crate::check_attr::target_from_impl_item;
 use crate::errors::{
     DuplicateLangItem, IncorrectTarget, LangItemOnIncorrectTarget, UnknownLangItem,
 };
 use crate::weak_lang_items;
 
-use rustc_hir as hir;
-use rustc_hir::def::DefKind;
+use rustc_ast as ast;
+use rustc_ast::visit;
+use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::lang_items::{extract, GenericRequirement};
-use rustc_hir::{LangItem, LanguageItems, Target};
-use rustc_middle::ty::TyCtxt;
+use rustc_hir::{LangItem, LanguageItems, MethodKind, Target};
+use rustc_middle::ty::{ResolverAstLowering, TyCtxt};
 use rustc_session::cstore::ExternCrate;
 use rustc_span::symbol::kw::Empty;
 use rustc_span::Span;
@@ -31,28 +31,55 @@ pub(crate) enum Duplicate {
     CrateDepends,
 }
 
-struct LanguageItemCollector<'tcx> {
+struct LanguageItemCollector<'ast, 'tcx> {
     items: LanguageItems,
     tcx: TyCtxt<'tcx>,
+    resolver: &'ast ResolverAstLowering,
+    // FIXME(#118552): We should probably feed def_span eagerly on def-id creation
+    // so we can avoid constructing this map for local def-ids.
+    item_spans: FxHashMap<DefId, Span>,
+    parent_item: Option<&'ast ast::Item>,
 }
 
-impl<'tcx> LanguageItemCollector<'tcx> {
-    fn new(tcx: TyCtxt<'tcx>) -> LanguageItemCollector<'tcx> {
-        LanguageItemCollector { tcx, items: LanguageItems::new() }
+impl<'ast, 'tcx> LanguageItemCollector<'ast, 'tcx> {
+    fn new(
+        tcx: TyCtxt<'tcx>,
+        resolver: &'ast ResolverAstLowering,
+    ) -> LanguageItemCollector<'ast, 'tcx> {
+        LanguageItemCollector {
+            tcx,
+            resolver,
+            items: LanguageItems::new(),
+            item_spans: FxHashMap::default(),
+            parent_item: None,
+        }
     }
 
-    fn check_for_lang(&mut self, actual_target: Target, def_id: LocalDefId) {
-        let attrs = self.tcx.hir().attrs(self.tcx.local_def_id_to_hir_id(def_id));
-        if let Some((name, span)) = extract(attrs) {
+    fn check_for_lang(
+        &mut self,
+        actual_target: Target,
+        def_id: LocalDefId,
+        attrs: &'ast [ast::Attribute],
+        item_span: Span,
+        generics: Option<&'ast ast::Generics>,
+    ) {
+        if let Some((name, attr_span)) = extract(attrs) {
             match LangItem::from_name(name) {
                 // Known lang item with attribute on correct target.
                 Some(lang_item) if actual_target == lang_item.target() => {
-                    self.collect_item_extended(lang_item, def_id, span);
+                    self.collect_item_extended(
+                        lang_item,
+                        def_id,
+                        item_span,
+                        attr_span,
+                        generics,
+                        actual_target,
+                    );
                 }
                 // Known lang item with attribute on incorrect target.
                 Some(lang_item) => {
                     self.tcx.sess.emit_err(LangItemOnIncorrectTarget {
-                        span,
+                        span: attr_span,
                         name,
                         expected_target: lang_item.target(),
                         actual_target,
@@ -60,127 +87,131 @@ impl<'tcx> LanguageItemCollector<'tcx> {
                 }
                 // Unknown lang item.
                 _ => {
-                    self.tcx.sess.emit_err(UnknownLangItem { span, name });
+                    self.tcx.sess.emit_err(UnknownLangItem { span: attr_span, name });
                 }
             }
         }
     }
 
-    fn collect_item(&mut self, lang_item: LangItem, item_def_id: DefId) {
+    fn collect_item(&mut self, lang_item: LangItem, item_def_id: DefId, item_span: Option<Span>) {
         // Check for duplicates.
-        if let Some(original_def_id) = self.items.get(lang_item) {
-            if original_def_id != item_def_id {
-                let local_span = self.tcx.hir().span_if_local(item_def_id);
-                let lang_item_name = lang_item.name();
-                let crate_name = self.tcx.crate_name(item_def_id.krate);
-                let mut dependency_of = Empty;
-                let is_local = item_def_id.is_local();
-                let path = if is_local {
-                    String::new()
-                } else {
-                    self.tcx
-                        .crate_extern_paths(item_def_id.krate)
-                        .iter()
-                        .map(|p| p.display().to_string())
-                        .collect::<Vec<_>>()
-                        .join(", ")
-                };
-                let first_defined_span = self.tcx.hir().span_if_local(original_def_id);
-                let mut orig_crate_name = Empty;
-                let mut orig_dependency_of = Empty;
-                let orig_is_local = original_def_id.is_local();
-                let orig_path = if orig_is_local {
-                    String::new()
-                } else {
-                    self.tcx
-                        .crate_extern_paths(original_def_id.krate)
-                        .iter()
-                        .map(|p| p.display().to_string())
-                        .collect::<Vec<_>>()
-                        .join(", ")
-                };
-                if first_defined_span.is_none() {
-                    orig_crate_name = self.tcx.crate_name(original_def_id.krate);
-                    if let Some(ExternCrate { dependency_of: inner_dependency_of, .. }) =
-                        self.tcx.extern_crate(original_def_id)
-                    {
-                        orig_dependency_of = self.tcx.crate_name(*inner_dependency_of);
-                    }
+        if let Some(original_def_id) = self.items.get(lang_item)
+            && original_def_id != item_def_id
+        {
+            let lang_item_name = lang_item.name();
+            let crate_name = self.tcx.crate_name(item_def_id.krate);
+            let mut dependency_of = Empty;
+            let is_local = item_def_id.is_local();
+            let path = if is_local {
+                String::new()
+            } else {
+                self.tcx
+                    .crate_extern_paths(item_def_id.krate)
+                    .iter()
+                    .map(|p| p.display().to_string())
+                    .collect::<Vec<_>>()
+                    .join(", ")
+            };
+
+            let first_defined_span = self.item_spans.get(&original_def_id).copied();
+            let mut orig_crate_name = Empty;
+            let mut orig_dependency_of = Empty;
+            let orig_is_local = original_def_id.is_local();
+            let orig_path = if orig_is_local {
+                String::new()
+            } else {
+                self.tcx
+                    .crate_extern_paths(original_def_id.krate)
+                    .iter()
+                    .map(|p| p.display().to_string())
+                    .collect::<Vec<_>>()
+                    .join(", ")
+            };
+
+            if first_defined_span.is_none() {
+                orig_crate_name = self.tcx.crate_name(original_def_id.krate);
+                if let Some(ExternCrate { dependency_of: inner_dependency_of, .. }) =
+                    self.tcx.extern_crate(original_def_id)
+                {
+                    orig_dependency_of = self.tcx.crate_name(*inner_dependency_of);
                 }
+            }
 
-                let duplicate = if local_span.is_some() {
-                    Duplicate::Plain
-                } else {
-                    match self.tcx.extern_crate(item_def_id) {
-                        Some(ExternCrate { dependency_of: inner_dependency_of, .. }) => {
-                            dependency_of = self.tcx.crate_name(*inner_dependency_of);
-                            Duplicate::CrateDepends
-                        }
-                        _ => Duplicate::Crate,
+            let duplicate = if item_span.is_some() {
+                Duplicate::Plain
+            } else {
+                match self.tcx.extern_crate(item_def_id) {
+                    Some(ExternCrate { dependency_of: inner_dependency_of, .. }) => {
+                        dependency_of = self.tcx.crate_name(*inner_dependency_of);
+                        Duplicate::CrateDepends
                     }
-                };
-
-                self.tcx.sess.emit_err(DuplicateLangItem {
-                    local_span,
-                    lang_item_name,
-                    crate_name,
-                    dependency_of,
-                    is_local,
-                    path,
-                    first_defined_span,
-                    orig_crate_name,
-                    orig_dependency_of,
-                    orig_is_local,
-                    orig_path,
-                    duplicate,
-                });
+                    _ => Duplicate::Crate,
+                }
+            };
+
+            self.tcx.sess.emit_err(DuplicateLangItem {
+                local_span: item_span,
+                lang_item_name,
+                crate_name,
+                dependency_of,
+                is_local,
+                path,
+                first_defined_span,
+                orig_crate_name,
+                orig_dependency_of,
+                orig_is_local,
+                orig_path,
+                duplicate,
+            });
+        } else {
+            // Matched.
+            self.items.set(lang_item, item_def_id);
+            // Collect span for error later
+            if let Some(item_span) = item_span {
+                self.item_spans.insert(item_def_id, item_span);
             }
         }
-
-        // Matched.
-        self.items.set(lang_item, item_def_id);
     }
 
     // Like collect_item() above, but also checks whether the lang item is declared
     // with the right number of generic arguments.
-    fn collect_item_extended(&mut self, lang_item: LangItem, item_def_id: LocalDefId, span: Span) {
+    fn collect_item_extended(
+        &mut self,
+        lang_item: LangItem,
+        item_def_id: LocalDefId,
+        item_span: Span,
+        attr_span: Span,
+        generics: Option<&'ast ast::Generics>,
+        target: Target,
+    ) {
         let name = lang_item.name();
 
-        // Now check whether the lang_item has the expected number of generic
-        // arguments. Generally speaking, binary and indexing operations have
-        // one (for the RHS/index), unary operations have none, the closure
-        // traits have one for the argument list, coroutines have one for the
-        // resume argument, and ordering/equality relations have one for the RHS
-        // Some other types like Box and various functions like drop_in_place
-        // have minimum requirements.
+        if let Some(generics) = generics {
+            // Now check whether the lang_item has the expected number of generic
+            // arguments. Generally speaking, binary and indexing operations have
+            // one (for the RHS/index), unary operations have none, the closure
+            // traits have one for the argument list, coroutines have one for the
+            // resume argument, and ordering/equality relations have one for the RHS
+            // Some other types like Box and various functions like drop_in_place
+            // have minimum requirements.
 
-        if let hir::Node::Item(hir::Item { kind, span: item_span, .. }) =
-            self.tcx.hir_node_by_def_id(item_def_id)
-        {
-            let (actual_num, generics_span) = match kind.generics() {
-                Some(generics) => (
-                    generics
-                        .params
-                        .iter()
-                        .filter(|p| {
-                            !matches!(
-                                p.kind,
-                                hir::GenericParamKind::Const { is_host_effect: true, .. }
-                            )
-                        })
-                        .count(),
-                    generics.span,
-                ),
-                None => (0, *item_span),
-            };
+            // FIXME: This still doesn't count, e.g., elided lifetimes and APITs.
+            let mut actual_num = generics.params.len();
+            if target.is_associated_item() {
+                actual_num += self
+                    .parent_item
+                    .unwrap()
+                    .opt_generics()
+                    .map_or(0, |generics| generics.params.len());
+            }
 
             let mut at_least = false;
             let required = match lang_item.required_generics() {
                 GenericRequirement::Exact(num) if num != actual_num => Some(num),
                 GenericRequirement::Minimum(num) if actual_num < num => {
                     at_least = true;
-                    Some(num)}
-                ,
+                    Some(num)
+                }
                 // If the number matches, or there is no requirement, handle it normally
                 _ => None,
             };
@@ -190,10 +221,10 @@ impl<'tcx> LanguageItemCollector<'tcx> {
                 // item kind of the target is correct, the target is still wrong
                 // because of the wrong number of generic arguments.
                 self.tcx.sess.emit_err(IncorrectTarget {
-                    span,
-                    generics_span,
+                    span: attr_span,
+                    generics_span: generics.span,
                     name: name.as_str(),
-                    kind: kind.descr(),
+                    kind: target.name(),
                     num,
                     actual_num,
                     at_least,
@@ -204,58 +235,117 @@ impl<'tcx> LanguageItemCollector<'tcx> {
             }
         }
 
-        self.collect_item(lang_item, item_def_id.to_def_id());
+        self.collect_item(lang_item, item_def_id.to_def_id(), Some(item_span));
     }
 }
 
 /// 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;
+
     // Initialize the collector.
-    let mut collector = LanguageItemCollector::new(tcx);
+    let mut collector = LanguageItemCollector::new(tcx, resolver);
 
     // Collect lang items in other crates.
     for &cnum in tcx.crates(()).iter() {
         for &(def_id, lang_item) in tcx.defined_lang_items(cnum).iter() {
-            collector.collect_item(lang_item, def_id);
+            collector.collect_item(lang_item, def_id, None);
         }
     }
 
-    // Collect lang items in this crate.
-    let crate_items = tcx.hir_crate_items(());
+    // Collect lang items local to this crate.
+    visit::Visitor::visit_crate(&mut collector, krate);
 
-    for id in crate_items.items() {
-        collector
-            .check_for_lang(Target::from_def_kind(tcx.def_kind(id.owner_id)), id.owner_id.def_id);
+    // Find all required but not-yet-defined lang items.
+    weak_lang_items::check_crate(tcx, &mut collector.items, krate);
 
-        if matches!(tcx.def_kind(id.owner_id), DefKind::Enum) {
-            let item = tcx.hir().item(id);
-            if let hir::ItemKind::Enum(def, ..) = &item.kind {
-                for variant in def.variants {
-                    collector.check_for_lang(Target::Variant, variant.def_id);
-                }
-            }
-        }
-    }
+    // Return all the lang items that were found.
+    collector.items
+}
+
+impl<'ast, 'tcx> visit::Visitor<'ast> for LanguageItemCollector<'ast, 'tcx> {
+    fn visit_item(&mut self, i: &'ast ast::Item) {
+        let target = match &i.kind {
+            ast::ItemKind::ExternCrate(_) => Target::ExternCrate,
+            ast::ItemKind::Use(_) => Target::Use,
+            ast::ItemKind::Static(_) => Target::Static,
+            ast::ItemKind::Const(_) => Target::Const,
+            ast::ItemKind::Fn(_) => Target::Fn,
+            ast::ItemKind::Mod(_, _) => Target::Mod,
+            ast::ItemKind::ForeignMod(_) => Target::ForeignFn,
+            ast::ItemKind::GlobalAsm(_) => Target::GlobalAsm,
+            ast::ItemKind::TyAlias(_) => Target::TyAlias,
+            ast::ItemKind::Enum(_, _) => Target::Enum,
+            ast::ItemKind::Struct(_, _) => Target::Struct,
+            ast::ItemKind::Union(_, _) => Target::Union,
+            ast::ItemKind::Trait(_) => Target::Trait,
+            ast::ItemKind::TraitAlias(_, _) => Target::TraitAlias,
+            ast::ItemKind::Impl(_) => Target::Impl,
+            ast::ItemKind::MacroDef(_) => Target::MacroDef,
+            ast::ItemKind::MacCall(_) => unreachable!("macros should have been expanded"),
+        };
 
-    // FIXME: avoid calling trait_item() when possible
-    for id in crate_items.trait_items() {
-        let item = tcx.hir().trait_item(id);
-        collector.check_for_lang(Target::from_trait_item(item), item.owner_id.def_id)
+        self.check_for_lang(
+            target,
+            self.resolver.node_id_to_def_id[&i.id],
+            &i.attrs,
+            i.span,
+            i.opt_generics(),
+        );
+
+        let parent_item = self.parent_item.replace(i);
+        visit::walk_item(self, i);
+        self.parent_item = parent_item;
     }
 
-    // FIXME: avoid calling impl_item() when possible
-    for id in crate_items.impl_items() {
-        let item = tcx.hir().impl_item(id);
-        collector.check_for_lang(target_from_impl_item(tcx, item), item.owner_id.def_id)
+    fn visit_enum_def(&mut self, enum_definition: &'ast ast::EnumDef) {
+        for variant in &enum_definition.variants {
+            self.check_for_lang(
+                Target::Variant,
+                self.resolver.node_id_to_def_id[&variant.id],
+                &variant.attrs,
+                variant.span,
+                None,
+            );
+        }
+
+        visit::walk_enum_def(self, enum_definition);
     }
 
-    // Extract out the found lang items.
-    let LanguageItemCollector { mut items, .. } = collector;
+    fn visit_assoc_item(&mut self, i: &'ast ast::AssocItem, ctxt: visit::AssocCtxt) {
+        let (target, generics) = match &i.kind {
+            ast::AssocItemKind::Fn(fun) => (
+                match &self.parent_item.unwrap().kind {
+                    ast::ItemKind::Impl(i) => {
+                        if i.of_trait.is_some() {
+                            Target::Method(MethodKind::Trait { body: fun.body.is_some() })
+                        } else {
+                            Target::Method(MethodKind::Inherent)
+                        }
+                    }
+                    ast::ItemKind::Trait(_) => {
+                        Target::Method(MethodKind::Trait { body: fun.body.is_some() })
+                    }
+                    _ => unreachable!(),
+                },
+                &fun.generics,
+            ),
+            ast::AssocItemKind::Const(ct) => (Target::AssocConst, &ct.generics),
+            ast::AssocItemKind::Type(ty) => (Target::AssocTy, &ty.generics),
+            ast::AssocItemKind::MacCall(_) => unreachable!("macros should have been expanded"),
+        };
 
-    // Find all required but not-yet-defined lang items.
-    weak_lang_items::check_crate(tcx, &mut items);
+        self.check_for_lang(
+            target,
+            self.resolver.node_id_to_def_id[&i.id],
+            &i.attrs,
+            i.span,
+            Some(generics),
+        );
 
-    items
+        visit::walk_assoc_item(self, i, ctxt);
+    }
 }
 
 pub fn provide(providers: &mut Providers) {
diff --git a/compiler/rustc_passes/src/weak_lang_items.rs b/compiler/rustc_passes/src/weak_lang_items.rs
index 9a6fb88c28110..b226c65e96c88 100644
--- a/compiler/rustc_passes/src/weak_lang_items.rs
+++ b/compiler/rustc_passes/src/weak_lang_items.rs
@@ -1,5 +1,7 @@
 //! Validity checking for weak lang items
 
+use rustc_ast as ast;
+use rustc_ast::visit;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir::lang_items::{self, LangItem};
 use rustc_hir::weak_lang_items::WEAK_LANG_ITEMS;
@@ -11,7 +13,7 @@ use crate::errors::{MissingLangItem, MissingPanicHandler, UnknownExternLangItem}
 
 /// Checks the crate for usage of weak lang items, returning a vector of all the
 /// language items required by this crate, but not defined yet.
-pub fn check_crate(tcx: TyCtxt<'_>, items: &mut lang_items::LanguageItems) {
+pub fn check_crate(tcx: TyCtxt<'_>, items: &mut lang_items::LanguageItems, krate: &ast::Crate) {
     // These are never called by user code, they're generated by the compiler.
     // They will never implicitly be added to the `missing` array unless we do
     // so here.
@@ -22,24 +24,30 @@ pub fn check_crate(tcx: TyCtxt<'_>, items: &mut lang_items::LanguageItems) {
         items.missing.push(LangItem::EhCatchTypeinfo);
     }
 
-    let crate_items = tcx.hir_crate_items(());
-    for id in crate_items.foreign_items() {
-        let attrs = tcx.hir().attrs(id.hir_id());
-        if let Some((lang_item, _)) = lang_items::extract(attrs) {
+    visit::Visitor::visit_crate(&mut WeakLangItemVisitor { tcx, items }, krate);
+
+    verify(tcx, items);
+}
+
+struct WeakLangItemVisitor<'a, 'tcx> {
+    tcx: TyCtxt<'tcx>,
+    items: &'a mut lang_items::LanguageItems,
+}
+
+impl<'ast> visit::Visitor<'ast> for WeakLangItemVisitor<'_, '_> {
+    fn visit_foreign_item(&mut self, i: &'ast ast::ForeignItem) {
+        if let Some((lang_item, _)) = lang_items::extract(&i.attrs) {
             if let Some(item) = LangItem::from_name(lang_item)
                 && item.is_weak()
             {
-                if items.get(item).is_none() {
-                    items.missing.push(item);
+                if self.items.get(item).is_none() {
+                    self.items.missing.push(item);
                 }
             } else {
-                let span = tcx.def_span(id.owner_id);
-                tcx.sess.emit_err(UnknownExternLangItem { span, lang_item });
+                self.tcx.sess.emit_err(UnknownExternLangItem { span: i.span, lang_item });
             }
         }
     }
-
-    verify(tcx, items);
 }
 
 fn verify(tcx: TyCtxt<'_>, items: &lang_items::LanguageItems) {
diff --git a/compiler/rustc_trait_selection/src/traits/coherence.rs b/compiler/rustc_trait_selection/src/traits/coherence.rs
index 818d14366596c..533fe32f70d87 100644
--- a/compiler/rustc_trait_selection/src/traits/coherence.rs
+++ b/compiler/rustc_trait_selection/src/traits/coherence.rs
@@ -273,7 +273,6 @@ fn overlap<'tcx>(
                                     causing the impls to overlap",
                                 infcx.resolve_vars_if_possible(failing_obligation.predicate)
                             ));
-                            lint
                         },
                     );
                 }
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index 9073cd6ac47a1..a1b896d225125 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -4665,7 +4665,7 @@ pub trait NextTypeParamName {
 impl NextTypeParamName for &[hir::GenericParam<'_>] {
     fn next_type_param_name(&self, name: Option<&str>) -> String {
         // This is the list of possible parameter names that we might suggest.
-        let name = name.and_then(|n| n.chars().next()).map(|c| c.to_string().to_uppercase());
+        let name = name.and_then(|n| n.chars().next()).map(|c| c.to_uppercase().to_string());
         let name = name.as_deref();
         let possible_names = [name.unwrap_or("T"), "T", "U", "V", "X", "Y", "Z", "A", "B", "C"];
         let used_names = self
@@ -4783,8 +4783,14 @@ pub fn suggest_desugaring_async_fn_to_impl_future_in_trait<'tcx>(
     };
 
     let future = tcx.hir_node_by_def_id(opaque_def_id).expect_item().expect_opaque_ty();
-    let Some(hir::GenericBound::LangItemTrait(_, _, _, generics)) = future.bounds.get(0) else {
-        // `async fn` should always lower to a lang item bound... but don't ICE.
+    let [hir::GenericBound::Trait(trait_ref, _)] = future.bounds else {
+        // `async fn` should always lower to a single bound... but don't ICE.
+        return None;
+    };
+    let Some(hir::PathSegment { args: Some(generics), .. }) =
+        trait_ref.trait_ref.path.segments.last()
+    else {
+        // desugaring to a single path segment for `Future<...>`.
         return None;
     };
     let Some(hir::TypeBindingKind::Equality { term: hir::Term::Ty(future_output_ty) }) =
diff --git a/compiler/rustc_trait_selection/src/traits/object_safety.rs b/compiler/rustc_trait_selection/src/traits/object_safety.rs
index fbde7455145c2..e3f89b3f5f699 100644
--- a/compiler/rustc_trait_selection/src/traits/object_safety.rs
+++ b/compiler/rustc_trait_selection/src/traits/object_safety.rs
@@ -194,7 +194,6 @@ fn lint_object_unsafe_trait(
                 // Only provide the help if its a local trait, otherwise it's not
                 violation.solution().add_to(err);
             }
-            err
         },
     );
 }
diff --git a/compiler/rustc_trait_selection/src/traits/specialize/mod.rs b/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
index 39f5ff52eba69..71a88f5f07cb6 100644
--- a/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
@@ -450,7 +450,6 @@ fn report_conflicting_impls<'tcx>(
                 msg,
                 |err| {
                     decorate(tcx, &overlap, impl_span, err);
-                    err
                 },
             );
         }
diff --git a/library/alloc/src/ffi/c_str.rs b/library/alloc/src/ffi/c_str.rs
index 62856fc9a49b5..4a4a3abd47f39 100644
--- a/library/alloc/src/ffi/c_str.rs
+++ b/library/alloc/src/ffi/c_str.rs
@@ -421,7 +421,7 @@ impl CString {
     /// Failure to call [`CString::from_raw`] will lead to a memory leak.
     ///
     /// The C side must **not** modify the length of the string (by writing a
-    /// `null` somewhere inside the string or removing the final one) before
+    /// nul byte somewhere inside the string or removing the final one) before
     /// it makes it back into Rust using [`CString::from_raw`]. See the safety section
     /// in [`CString::from_raw`].
     ///
@@ -797,7 +797,7 @@ impl From<Box<CStr>> for CString {
 #[stable(feature = "cstring_from_vec_of_nonzerou8", since = "1.43.0")]
 impl From<Vec<NonZeroU8>> for CString {
     /// Converts a <code>[Vec]<[NonZeroU8]></code> into a [`CString`] without
-    /// copying nor checking for inner null bytes.
+    /// copying nor checking for inner nul bytes.
     #[inline]
     fn from(v: Vec<NonZeroU8>) -> CString {
         unsafe {
@@ -809,7 +809,7 @@ impl From<Vec<NonZeroU8>> for CString {
                 let (ptr, len, cap): (*mut NonZeroU8, _, _) = Vec::into_raw_parts(v);
                 Vec::from_raw_parts(ptr.cast::<u8>(), len, cap)
             };
-            // SAFETY: `v` cannot contain null bytes, given the type-level
+            // SAFETY: `v` cannot contain nul bytes, given the type-level
             // invariant of `NonZeroU8`.
             Self::_from_vec_unchecked(v)
         }
diff --git a/library/core/src/ffi/c_str.rs b/library/core/src/ffi/c_str.rs
index e7ec1fb73cdb5..bb839a71e90e6 100644
--- a/library/core/src/ffi/c_str.rs
+++ b/library/core/src/ffi/c_str.rs
@@ -205,7 +205,7 @@ impl CStr {
     /// * The memory pointed to by `ptr` must contain a valid nul terminator at the
     ///   end of the string.
     ///
-    /// * `ptr` must be [valid] for reads of bytes up to and including the null terminator.
+    /// * `ptr` must be [valid] for reads of bytes up to and including the nul terminator.
     ///   This means in particular:
     ///
     ///     * The entire memory range of this `CStr` must be contained within a single allocated object!
@@ -415,7 +415,7 @@ impl CStr {
             let mut i = bytes.len().saturating_sub(1);
             assert!(!bytes.is_empty() && bytes[i] == 0, "input was not nul-terminated");
 
-            // Ending null byte exists, skip to the rest.
+            // Ending nul byte exists, skip to the rest.
             while i != 0 {
                 i -= 1;
                 let byte = bytes[i];
diff --git a/library/core/src/net/ip_addr.rs b/library/core/src/net/ip_addr.rs
index dafc58d3a7d91..8bf15c736c34b 100644
--- a/library/core/src/net/ip_addr.rs
+++ b/library/core/src/net/ip_addr.rs
@@ -1437,7 +1437,7 @@ impl Ipv6Addr {
     /// - The [unspecified address] ([`is_unspecified`](Ipv6Addr::is_unspecified))
     /// - The [loopback address] ([`is_loopback`](Ipv6Addr::is_loopback))
     /// - IPv4-mapped addresses
-    /// - Addresses reserved for benchmarking
+    /// - Addresses reserved for benchmarking ([`is_benchmarking`](Ipv6Addr::is_benchmarking))
     /// - Addresses reserved for documentation ([`is_documentation`](Ipv6Addr::is_documentation))
     /// - Unique local addresses ([`is_unique_local`](Ipv6Addr::is_unique_local))
     /// - Unicast addresses with link-local scope ([`is_unicast_link_local`](Ipv6Addr::is_unicast_link_local))
diff --git a/library/std/src/panicking.rs b/library/std/src/panicking.rs
index 55f4917a93705..66b4ec37c8ec5 100644
--- a/library/std/src/panicking.rs
+++ b/library/std/src/panicking.rs
@@ -588,7 +588,7 @@ pub fn panicking() -> bool {
 }
 
 /// Entry point of panics from the core crate (`panic_impl` lang item).
-#[cfg(not(test))]
+#[cfg(not(any(test, doctest)))]
 #[panic_handler]
 pub fn begin_panic_handler(info: &PanicInfo<'_>) -> ! {
     struct FormatStringPayload<'a> {
@@ -669,7 +669,7 @@ pub fn begin_panic_handler(info: &PanicInfo<'_>) -> ! {
 /// panic!() and assert!(). In particular, this is the only entry point that supports
 /// arbitrary payloads, not just format strings.
 #[unstable(feature = "libstd_sys_internals", reason = "used by the panic! macro", issue = "none")]
-#[cfg_attr(not(test), lang = "begin_panic")]
+#[cfg_attr(not(any(test, doctest)), lang = "begin_panic")]
 // lang item for CTFE panic support
 // never inline unless panic_immediate_abort to avoid code
 // bloat at the call sites as much as possible
diff --git a/library/std/src/process.rs b/library/std/src/process.rs
index 6004ed51bd164..4a7f5d8e0bee6 100644
--- a/library/std/src/process.rs
+++ b/library/std/src/process.rs
@@ -2311,7 +2311,7 @@ pub fn id() -> u32 {
 /// of the `main` function, this trait is likely to be available only on
 /// standard library's runtime for convenience. Other runtimes are not required
 /// to provide similar functionality.
-#[cfg_attr(not(test), lang = "termination")]
+#[cfg_attr(not(any(test, doctest)), lang = "termination")]
 #[stable(feature = "termination_trait_lib", since = "1.61.0")]
 #[rustc_on_unimplemented(on(
     cause = "MainFunctionType",
diff --git a/library/std/src/rt.rs b/library/std/src/rt.rs
index f1eeb75be7c4d..335944845ae0b 100644
--- a/library/std/src/rt.rs
+++ b/library/std/src/rt.rs
@@ -154,7 +154,7 @@ fn lang_start_internal(
     ret_code
 }
 
-#[cfg(not(test))]
+#[cfg(not(any(test, doctest)))]
 #[lang = "start"]
 fn lang_start<T: crate::process::Termination + 'static>(
     main: fn() -> T,
diff --git a/library/std/src/sys/personality/mod.rs b/library/std/src/sys/personality/mod.rs
index 0fff53f18875b..d37b8ce634654 100644
--- a/library/std/src/sys/personality/mod.rs
+++ b/library/std/src/sys/personality/mod.rs
@@ -12,7 +12,7 @@
 
 mod dwarf;
 
-#[cfg(not(test))]
+#[cfg(not(any(test, doctest)))]
 cfg_if::cfg_if! {
     if #[cfg(target_os = "emscripten")] {
         mod emcc;
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 6631c42727099..b11bddbbdfe3d 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -184,22 +184,6 @@ fn clean_generic_bound<'tcx>(
 ) -> Option<GenericBound> {
     Some(match *bound {
         hir::GenericBound::Outlives(lt) => GenericBound::Outlives(clean_lifetime(lt, cx)),
-        hir::GenericBound::LangItemTrait(lang_item, span, _, generic_args) => {
-            let def_id = cx.tcx.require_lang_item(lang_item, Some(span));
-
-            let trait_ref = ty::Binder::dummy(ty::TraitRef::identity(cx.tcx, def_id));
-
-            let generic_args = clean_generic_args(generic_args, cx);
-            let GenericArgs::AngleBracketed { bindings, .. } = generic_args else {
-                bug!("clean: parenthesized `GenericBound::LangItemTrait`");
-            };
-
-            let trait_ = clean_trait_ref_with_bindings(cx, trait_ref, bindings);
-            GenericBound::TraitBound(
-                PolyTrait { trait_, generic_params: vec![] },
-                hir::TraitBoundModifier::None,
-            )
-        }
         hir::GenericBound::Trait(ref t, modifier) => {
             // `T: ~const Destruct` is hidden because `T: Destruct` is a no-op.
             if modifier == hir::TraitBoundModifier::MaybeConst
diff --git a/src/librustdoc/core.rs b/src/librustdoc/core.rs
index 8215926ee331f..0150496990d2d 100644
--- a/src/librustdoc/core.rs
+++ b/src/librustdoc/core.rs
@@ -380,7 +380,9 @@ pub(crate) fn run_global_ctxt(
             crate::lint::MISSING_CRATE_LEVEL_DOCS,
             DocContext::as_local_hir_id(tcx, krate.module.item_id).unwrap(),
             "no documentation found for this crate's top-level module",
-            |lint| lint.help(help),
+            |lint| {
+                lint.help(help);
+            },
         );
     }
 
diff --git a/src/librustdoc/html/markdown.rs b/src/librustdoc/html/markdown.rs
index dbd78ea0dc97c..6f667d18e355e 100644
--- a/src/librustdoc/html/markdown.rs
+++ b/src/librustdoc/html/markdown.rs
@@ -835,7 +835,7 @@ impl<'tcx> ExtraInfo<'tcx> {
                 self.tcx.local_def_id_to_hir_id(def_id),
                 self.sp,
                 msg,
-                |l| l,
+                |_| {},
             );
         }
     }
@@ -843,9 +843,7 @@ impl<'tcx> ExtraInfo<'tcx> {
     fn error_invalid_codeblock_attr_with_help(
         &self,
         msg: impl Into<DiagnosticMessage>,
-        f: impl for<'a, 'b> FnOnce(
-            &'b mut DiagnosticBuilder<'a, ()>,
-        ) -> &'b mut DiagnosticBuilder<'a, ()>,
+        f: impl for<'a, 'b> FnOnce(&'b mut DiagnosticBuilder<'a, ()>),
     ) {
         if let Some(def_id) = self.def_id.as_local() {
             self.tcx.struct_span_lint_hir(
@@ -1296,7 +1294,7 @@ impl LangString {
                                     lint.help(format!(
                                         "there is an attribute with a similar name: `edition{}`",
                                         &x[4..],
-                                    ))
+                                    ));
                                 },
                             );
                         }
@@ -1350,7 +1348,7 @@ impl LangString {
                                         lint.help(format!(
                                             "there is an attribute with a similar name: `{flag}`"
                                         ))
-                                        .help(help)
+                                        .help(help);
                                     },
                                 );
                             }
diff --git a/src/librustdoc/passes/check_doc_test_visibility.rs b/src/librustdoc/passes/check_doc_test_visibility.rs
index 8d5b17f43cdcd..a931e8804d9cb 100644
--- a/src/librustdoc/passes/check_doc_test_visibility.rs
+++ b/src/librustdoc/passes/check_doc_test_visibility.rs
@@ -131,7 +131,7 @@ pub(crate) fn look_for_tests<'tcx>(cx: &DocContext<'tcx>, dox: &str, item: &Item
                 hir_id,
                 sp,
                 "missing code example in this documentation",
-                |lint| lint,
+                |_| {},
             );
         }
     } else if tests.found_tests > 0
@@ -142,7 +142,7 @@ pub(crate) fn look_for_tests<'tcx>(cx: &DocContext<'tcx>, dox: &str, item: &Item
             hir_id,
             item.attr_span(cx.tcx),
             "documentation test in private item",
-            |lint| lint,
+            |_| {},
         );
     }
 }
diff --git a/src/librustdoc/passes/collect_intra_doc_links.rs b/src/librustdoc/passes/collect_intra_doc_links.rs
index 6b536e97c43cf..ee185ab98922d 100644
--- a/src/librustdoc/passes/collect_intra_doc_links.rs
+++ b/src/librustdoc/passes/collect_intra_doc_links.rs
@@ -1755,8 +1755,6 @@ fn report_diagnostic(
         }
 
         decorate(lint, span, link_range);
-
-        lint
     });
 }
 
diff --git a/src/librustdoc/passes/lint/bare_urls.rs b/src/librustdoc/passes/lint/bare_urls.rs
index 0c5cfffe1be53..bffa17da3b4c7 100644
--- a/src/librustdoc/passes/lint/bare_urls.rs
+++ b/src/librustdoc/passes/lint/bare_urls.rs
@@ -31,7 +31,7 @@ pub(super) fn visit_item(cx: &DocContext<'_>, item: &Item) {
                             "use an automatic link instead",
                             format!("<{url}>"),
                             Applicability::MachineApplicable,
-                        )
+                        );
                 });
             };
 
diff --git a/src/librustdoc/passes/lint/check_code_block_syntax.rs b/src/librustdoc/passes/lint/check_code_block_syntax.rs
index e9b9e36a53030..b5583ae45209f 100644
--- a/src/librustdoc/passes/lint/check_code_block_syntax.rs
+++ b/src/librustdoc/passes/lint/check_code_block_syntax.rs
@@ -131,8 +131,6 @@ fn check_rust_syntax(
         for message in buffer.messages.iter() {
             lint.note(message.clone());
         }
-
-        lint
     });
 }
 
diff --git a/src/librustdoc/passes/lint/html_tags.rs b/src/librustdoc/passes/lint/html_tags.rs
index 4a80c22ed0851..90874c01102e5 100644
--- a/src/librustdoc/passes/lint/html_tags.rs
+++ b/src/librustdoc/passes/lint/html_tags.rs
@@ -89,7 +89,7 @@ pub(crate) fn visit_item(cx: &DocContext<'_>, item: &Item) {
                     if (generics_start > 0 && dox.as_bytes()[generics_start - 1] == b'<')
                         || (generics_end < dox.len() && dox.as_bytes()[generics_end] == b'>')
                     {
-                        return lint;
+                        return;
                     }
                     // multipart form is chosen here because ``Vec<i32>`` would be confusing.
                     lint.multipart_suggestion(
@@ -101,8 +101,6 @@ pub(crate) fn visit_item(cx: &DocContext<'_>, item: &Item) {
                         Applicability::MaybeIncorrect,
                     );
                 }
-
-                lint
             });
         };
 
diff --git a/src/librustdoc/passes/lint/redundant_explicit_links.rs b/src/librustdoc/passes/lint/redundant_explicit_links.rs
index 472781e7d2294..4491d20b478d0 100644
--- a/src/librustdoc/passes/lint/redundant_explicit_links.rs
+++ b/src/librustdoc/passes/lint/redundant_explicit_links.rs
@@ -181,8 +181,6 @@ fn check_inline_or_reference_unknown_redundancy(
                 .span_label(display_span, "because label contains path that resolves to same destination")
                 .note("when a link's destination is not specified,\nthe label is used to resolve intra-doc links")
                 .span_suggestion_with_style(link_span, "remove explicit link target", format!("[{}]", link_data.display_link), Applicability::MaybeIncorrect, SuggestionStyle::ShowAlways);
-
-            lint
         });
     }
 
@@ -234,8 +232,6 @@ fn check_reference_redundancy(
                 .span_note(def_span, "referenced explicit link target defined here")
                 .note("when a link's destination is not specified,\nthe label is used to resolve intra-doc links")
                 .span_suggestion_with_style(link_span, "remove explicit link target", format!("[{}]", link_data.display_link), Applicability::MaybeIncorrect, SuggestionStyle::ShowAlways);
-
-            lint
         });
     }
 
diff --git a/src/librustdoc/passes/lint/unescaped_backticks.rs b/src/librustdoc/passes/lint/unescaped_backticks.rs
index 8b7fdd6ab1f93..0893cd0b40b52 100644
--- a/src/librustdoc/passes/lint/unescaped_backticks.rs
+++ b/src/librustdoc/passes/lint/unescaped_backticks.rs
@@ -111,8 +111,6 @@ pub(crate) fn visit_item(cx: &DocContext<'_>, item: &Item) {
                     }
 
                     suggest_insertion(cx, item, &dox, lint, backtick_index, '\\', "if you meant to use a literal backtick, escape it");
-
-                    lint
                 });
             }
             Event::Code(_) => {
diff --git a/src/tools/clippy/clippy_lints/src/len_zero.rs b/src/tools/clippy/clippy_lints/src/len_zero.rs
index 83af551fcd3ca..8c032b1702360 100644
--- a/src/tools/clippy/clippy_lints/src/len_zero.rs
+++ b/src/tools/clippy/clippy_lints/src/len_zero.rs
@@ -8,8 +8,8 @@ use rustc_hir::def::Res;
 use rustc_hir::def_id::{DefId, DefIdSet};
 use rustc_hir::{
     AssocItemKind, BinOpKind, Expr, ExprKind, FnRetTy, GenericArg, GenericBound, ImplItem, ImplItemKind,
-    ImplicitSelfKind, Item, ItemKind, LangItem, Mutability, Node, PatKind, PathSegment, PrimTy, QPath, TraitItemRef,
-    TyKind, TypeBindingKind,
+    ImplicitSelfKind, Item, ItemKind, Mutability, Node, PatKind, PathSegment, PrimTy, QPath, TraitItemRef,
+    TyKind, TypeBindingKind, OpaqueTyOrigin,
 };
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::{self, AssocKind, FnSig, Ty};
@@ -289,8 +289,10 @@ fn extract_future_output<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<&
             kind: ItemKind::OpaqueTy(opaque),
             ..
         } = item
-        && opaque.bounds.len() == 1
-        && let GenericBound::LangItemTrait(LangItem::Future, _, _, generic_args) = &opaque.bounds[0]
+        && let OpaqueTyOrigin::AsyncFn(_) = opaque.origin
+        && let [GenericBound::Trait(trait_ref, _)] = &opaque.bounds
+        && let Some(segment) = trait_ref.trait_ref.path.segments.last()
+        && let Some(generic_args) = segment.args
         && generic_args.bindings.len() == 1
         && let TypeBindingKind::Equality {
             term:
diff --git a/src/tools/clippy/clippy_utils/src/diagnostics.rs b/src/tools/clippy/clippy_utils/src/diagnostics.rs
index fa56e5b0ba2bd..7562961538e30 100644
--- a/src/tools/clippy/clippy_utils/src/diagnostics.rs
+++ b/src/tools/clippy/clippy_utils/src/diagnostics.rs
@@ -49,7 +49,6 @@ pub fn span_lint<T: LintContext>(cx: &T, lint: &'static Lint, sp: impl Into<Mult
     #[expect(clippy::disallowed_methods)]
     cx.struct_span_lint(lint, sp, msg.to_string(), |diag| {
         docs_link(diag, lint);
-        diag
     });
 }
 
@@ -90,7 +89,6 @@ pub fn span_lint_and_help<T: LintContext>(
             diag.help(help.to_string());
         }
         docs_link(diag, lint);
-        diag
     });
 }
 
@@ -134,7 +132,6 @@ pub fn span_lint_and_note<T: LintContext>(
             diag.note(note);
         }
         docs_link(diag, lint);
-        diag
     });
 }
 
@@ -152,7 +149,6 @@ where
     cx.struct_span_lint(lint, sp, msg.to_string(), |diag| {
         f(diag);
         docs_link(diag, lint);
-        diag
     });
 }
 
@@ -160,7 +156,6 @@ pub fn span_lint_hir(cx: &LateContext<'_>, lint: &'static Lint, hir_id: HirId, s
     #[expect(clippy::disallowed_methods)]
     cx.tcx.struct_span_lint_hir(lint, hir_id, sp, msg.to_string(), |diag| {
         docs_link(diag, lint);
-        diag
     });
 }
 
@@ -176,7 +171,6 @@ pub fn span_lint_hir_and_then(
     cx.tcx.struct_span_lint_hir(lint, hir_id, sp, msg.to_string(), |diag| {
         f(diag);
         docs_link(diag, lint);
-        diag
     });
 }
 
diff --git a/tests/ui/duplicate_entry_error.stderr b/tests/ui/duplicate_entry_error.stderr
index 592640a884c9a..3b5998df353c4 100644
--- a/tests/ui/duplicate_entry_error.stderr
+++ b/tests/ui/duplicate_entry_error.stderr
@@ -1,8 +1,11 @@
 error[E0152]: found duplicate lang item `panic_impl`
   --> $DIR/duplicate_entry_error.rs:11:1
    |
-LL | fn panic_impl(info: &PanicInfo) -> ! {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | / fn panic_impl(info: &PanicInfo) -> ! {
+LL | |
+LL | |     loop {}
+LL | | }
+   | |_^
    |
    = note: the lang item is first defined in crate `std` (which `duplicate_entry_error` depends on)
    = note: first definition in `std` loaded from SYSROOT/libstd-*.rlib
diff --git a/tests/ui/error-codes/E0152.stderr b/tests/ui/error-codes/E0152.stderr
index 816ba2d569b6b..dbea7e6d27fbe 100644
--- a/tests/ui/error-codes/E0152.stderr
+++ b/tests/ui/error-codes/E0152.stderr
@@ -2,7 +2,7 @@ error[E0152]: found duplicate lang item `owned_box`
   --> $DIR/E0152.rs:5:1
    |
 LL | struct Foo<T>(T);
-   | ^^^^^^^^^^^^^
+   | ^^^^^^^^^^^^^^^^^
    |
    = note: the lang item is first defined in crate `alloc` (which `std` depends on)
    = note: first definition in `alloc` loaded from SYSROOT/liballoc-*.rlib
diff --git a/tests/ui/error-codes/E0264.stderr b/tests/ui/error-codes/E0264.stderr
index 14a4ffbe31666..3503fb229e4f3 100644
--- a/tests/ui/error-codes/E0264.stderr
+++ b/tests/ui/error-codes/E0264.stderr
@@ -2,7 +2,7 @@ error[E0264]: unknown external lang item: `cake`
   --> $DIR/E0264.rs:5:5
    |
 LL |     fn cake();
-   |     ^^^^^^^^^
+   |     ^^^^^^^^^^
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/lang-items/lang-item-generic-requirements.rs b/tests/ui/lang-items/lang-item-generic-requirements.rs
index 3d33adf68316b..21bd7187e15b4 100644
--- a/tests/ui/lang-items/lang-item-generic-requirements.rs
+++ b/tests/ui/lang-items/lang-item-generic-requirements.rs
@@ -22,6 +22,8 @@ trait MyIndex<'a, T> {}
 #[lang = "phantom_data"]
 //~^ ERROR `phantom_data` language item must be applied to a struct with 1 generic argument
 struct MyPhantomData<T, U>;
+//~^ ERROR parameter `T` is never used
+//~| ERROR parameter `U` is never used
 
 #[lang = "owned_box"]
 //~^ ERROR `owned_box` language item must be applied to a struct with at least 1 generic argument
@@ -40,6 +42,7 @@ fn ice() {
     let r = 5;
     let a = 6;
     r + a;
+    //~^ ERROR cannot add `{integer}` to `{integer}`
 
     // Use drop in place
     my_ptr_drop();
diff --git a/tests/ui/lang-items/lang-item-generic-requirements.stderr b/tests/ui/lang-items/lang-item-generic-requirements.stderr
index 4d349a25f9c2a..8072e6797e49c 100644
--- a/tests/ui/lang-items/lang-item-generic-requirements.stderr
+++ b/tests/ui/lang-items/lang-item-generic-requirements.stderr
@@ -33,7 +33,7 @@ LL | struct MyPhantomData<T, U>;
    |                     ------ this struct has 2 generic arguments
 
 error[E0718]: `owned_box` language item must be applied to a struct with at least 1 generic argument
-  --> $DIR/lang-item-generic-requirements.rs:26:1
+  --> $DIR/lang-item-generic-requirements.rs:28:1
    |
 LL | #[lang = "owned_box"]
    | ^^^^^^^^^^^^^^^^^^^^^
@@ -42,7 +42,7 @@ LL | struct Foo;
    |           - this struct has 0 generic arguments
 
 error[E0718]: `start` language item must be applied to a function with 1 generic argument
-  --> $DIR/lang-item-generic-requirements.rs:32:1
+  --> $DIR/lang-item-generic-requirements.rs:34:1
    |
 LL | #[lang = "start"]
    | ^^^^^^^^^^^^^^^^^
@@ -50,6 +50,35 @@ LL |
 LL | fn start(_: *const u8, _: isize, _: *const *const u8) -> isize {
    |         - this function has 0 generic arguments
 
-error: aborting due to 6 previous errors
+error[E0392]: parameter `T` is never used
+  --> $DIR/lang-item-generic-requirements.rs:24:22
+   |
+LL | struct MyPhantomData<T, U>;
+   |                      ^ unused parameter
+   |
+   = help: consider removing `T` or referring to it in a field
+   = help: if you intended `T` to be a const parameter, use `const T: usize` instead
+
+error[E0392]: parameter `U` is never used
+  --> $DIR/lang-item-generic-requirements.rs:24:25
+   |
+LL | struct MyPhantomData<T, U>;
+   |                         ^ unused parameter
+   |
+   = help: consider removing `U` or referring to it in a field
+   = help: if you intended `U` to be a const parameter, use `const U: usize` instead
+
+error[E0369]: cannot add `{integer}` to `{integer}`
+  --> $DIR/lang-item-generic-requirements.rs:44:7
+   |
+LL |     r + a;
+   |     - ^ - {integer}
+   |     |
+   |     {integer}
+
+error: requires `copy` lang_item
+
+error: aborting due to 10 previous errors
 
-For more information about this error, try `rustc --explain E0718`.
+Some errors have detailed explanations: E0369, E0392, E0718.
+For more information about an error, try `rustc --explain E0369`.
diff --git a/tests/ui/panic-handler/panic-handler-duplicate.stderr b/tests/ui/panic-handler/panic-handler-duplicate.stderr
index 5c50b7016b20d..299847474cd58 100644
--- a/tests/ui/panic-handler/panic-handler-duplicate.stderr
+++ b/tests/ui/panic-handler/panic-handler-duplicate.stderr
@@ -1,14 +1,18 @@
 error[E0152]: found duplicate lang item `panic_impl`
   --> $DIR/panic-handler-duplicate.rs:15:1
    |
-LL | fn panic2(info: &PanicInfo) -> ! {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | / fn panic2(info: &PanicInfo) -> ! {
+LL | |     loop {}
+LL | | }
+   | |_^
    |
 note: the lang item is first defined here
   --> $DIR/panic-handler-duplicate.rs:10:1
    |
-LL | fn panic(info: &PanicInfo) -> ! {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | / fn panic(info: &PanicInfo) -> ! {
+LL | |     loop {}
+LL | | }
+   | |_^
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/panic-handler/panic-handler-std.stderr b/tests/ui/panic-handler/panic-handler-std.stderr
index ad9addec8eb4d..48c216ce27ec4 100644
--- a/tests/ui/panic-handler/panic-handler-std.stderr
+++ b/tests/ui/panic-handler/panic-handler-std.stderr
@@ -1,8 +1,10 @@
 error[E0152]: found duplicate lang item `panic_impl`
   --> $DIR/panic-handler-std.rs:8:1
    |
-LL | fn panic(info: PanicInfo) -> ! {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | / fn panic(info: PanicInfo) -> ! {
+LL | |     loop {}
+LL | | }
+   | |_^
    |
    = note: the lang item is first defined in crate `std` (which `panic_handler_std` depends on)
    = note: first definition in `std` loaded from SYSROOT/libstd-*.rlib
diff --git a/tests/ui/traits/issue-102989.rs b/tests/ui/traits/issue-102989.rs
index 216cd78e56f9a..f1ecee0a552a7 100644
--- a/tests/ui/traits/issue-102989.rs
+++ b/tests/ui/traits/issue-102989.rs
@@ -7,6 +7,7 @@ trait Sized { } //~ ERROR found duplicate lang item `sized`
 fn ref_Struct(self: &Struct, f: &u32) -> &u32 {
     //~^ ERROR `self` parameter is only allowed in associated functions
     //~| ERROR cannot find type `Struct` in this scope
+    //~| ERROR mismatched types
     let x = x << 1;
     //~^ ERROR cannot find value `x` in this scope
 }
diff --git a/tests/ui/traits/issue-102989.stderr b/tests/ui/traits/issue-102989.stderr
index 7d0098fe88502..40e49df2b2d96 100644
--- a/tests/ui/traits/issue-102989.stderr
+++ b/tests/ui/traits/issue-102989.stderr
@@ -13,7 +13,7 @@ LL | fn ref_Struct(self: &Struct, f: &u32) -> &u32 {
    |                      ^^^^^^ not found in this scope
 
 error[E0425]: cannot find value `x` in this scope
-  --> $DIR/issue-102989.rs:10:13
+  --> $DIR/issue-102989.rs:11:13
    |
 LL |     let x = x << 1;
    |             ^ help: a local variable with a similar name exists: `f`
@@ -22,13 +22,27 @@ error[E0152]: found duplicate lang item `sized`
   --> $DIR/issue-102989.rs:5:1
    |
 LL | trait Sized { }
-   | ^^^^^^^^^^^
+   | ^^^^^^^^^^^^^^^
    |
    = note: the lang item is first defined in crate `core` (which `std` depends on)
    = note: first definition in `core` loaded from SYSROOT/libcore-*.rlib
    = note: second definition in the local crate (`issue_102989`)
 
-error: aborting due to 4 previous errors
+error[E0308]: mismatched types
+  --> $DIR/issue-102989.rs:7:42
+   |
+LL | fn ref_Struct(self: &Struct, f: &u32) -> &u32 {
+   |    ----------                            ^^^^ expected `&u32`, found `()`
+   |    |
+   |    implicitly returns `()` as its body has no tail or `return` expression
+   |
+help: consider returning the local binding `f`
+   |
+LL ~     let x = x << 1;
+LL +     f
+   |
+
+error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0152, E0412, E0425.
+Some errors have detailed explanations: E0152, E0308, E0412, E0425.
 For more information about an error, try `rustc --explain E0152`.