Auto merge of #111089 - Dylan-DPC:rollup-b8oj6du, r=Dylan-DPC

Rollup of 7 pull requests

Successful merges:

 - #105076 (Refactor core::char::EscapeDefault and co. structures)
 - #108161 (Add `ConstParamTy` trait)
 - #108668 (Stabilize debugger_visualizer)
 - #110512 (Fix elaboration with associated type bounds)
 - #110895 (Remove `all` in target_thread_local cfg)
 - #110955 (uplift `clippy::clone_double_ref` as `suspicious_double_ref_op`)
 - #111048 (Mark`feature(return_position_impl_trait_in_trait)` and`feature(async_fn_in_trait)` as not incomplete)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

134 files changed, 1699 insertions, 1153 deletions

diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index c63e156beae..4baac4b5afc 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -40,7 +40,6 @@ use regex::Regex;
 use tempfile::Builder as TempFileBuilder;
 
 use itertools::Itertools;
-use std::borrow::Borrow;
 use std::cell::OnceCell;
 use std::collections::BTreeSet;
 use std::ffi::OsString;
@@ -576,17 +575,17 @@ fn link_dwarf_object<'a>(
 
     impl<Relocations> ThorinSession<Relocations> {
         fn alloc_mmap(&self, data: Mmap) -> &Mmap {
-            (*self.arena_mmap.alloc(data)).borrow()
+            &*self.arena_mmap.alloc(data)
         }
     }
 
     impl<Relocations> thorin::Session<Relocations> for ThorinSession<Relocations> {
         fn alloc_data(&self, data: Vec<u8>) -> &[u8] {
-            (*self.arena_data.alloc(data)).borrow()
+            &*self.arena_data.alloc(data)
         }
 
         fn alloc_relocation(&self, data: Relocations) -> &Relocations {
-            (*self.arena_relocations.alloc(data)).borrow()
+            &*self.arena_relocations.alloc(data)
         }
 
         fn read_input(&self, path: &Path) -> std::io::Result<&[u8]> {
diff --git a/compiler/rustc_feature/src/accepted.rs b/compiler/rustc_feature/src/accepted.rs
index 3b9fc5e9a51..70d608a5ea4 100644
--- a/compiler/rustc_feature/src/accepted.rs
+++ b/compiler/rustc_feature/src/accepted.rs
@@ -130,6 +130,8 @@ declare_features! (
     (accepted, copy_closures, "1.26.0", Some(44490), None),
     /// Allows `crate` in paths.
     (accepted, crate_in_paths, "1.30.0", Some(45477), None),
+    /// Allows using `#[debugger_visualizer]` attribute.
+    (accepted, debugger_visualizer, "CURRENT_RUSTC_VERSION", Some(95939), None),
     /// Allows rustc to inject a default alloc_error_handler
     (accepted, default_alloc_error_handler, "1.68.0", Some(66741), None),
     /// Allows using assigning a default type to type parameters in algebraic data type definitions.
diff --git a/compiler/rustc_feature/src/active.rs b/compiler/rustc_feature/src/active.rs
index f046022b842..6201e5b619b 100644
--- a/compiler/rustc_feature/src/active.rs
+++ b/compiler/rustc_feature/src/active.rs
@@ -310,7 +310,7 @@ declare_features! (
     /// Allows `async || body` closures.
     (active, async_closure, "1.37.0", Some(62290), None),
     /// Allows async functions to be declared, implemented, and used in traits.
-    (incomplete, async_fn_in_trait, "1.66.0", Some(91611), None),
+    (active, async_fn_in_trait, "1.66.0", Some(91611), None),
     /// Treat `extern "C"` function as nounwind.
     (active, c_unwind, "1.52.0", Some(74990), None),
     /// Allows using C-variadics.
@@ -363,8 +363,6 @@ declare_features! (
     (active, custom_inner_attributes, "1.30.0", Some(54726), None),
     /// Allows custom test frameworks with `#![test_runner]` and `#[test_case]`.
     (active, custom_test_frameworks, "1.30.0", Some(50297), None),
-    /// Allows using `#[debugger_visualizer]`.
-    (active, debugger_visualizer, "1.62.0", Some(95939), None),
     /// Allows declarative macros 2.0 (`macro`).
     (active, decl_macro, "1.17.0", Some(39412), None),
     /// Allows default type parameters to influence type inference.
@@ -496,7 +494,7 @@ declare_features! (
     /// Allows `repr(simd)` and importing the various simd intrinsics.
     (active, repr_simd, "1.4.0", Some(27731), None),
     /// Allows return-position `impl Trait` in traits.
-    (incomplete, return_position_impl_trait_in_trait, "1.65.0", Some(91611), None),
+    (active, return_position_impl_trait_in_trait, "1.65.0", Some(91611), None),
     /// Allows bounding the return type of AFIT/RPITIT.
     (incomplete, return_type_notation, "1.70.0", Some(109417), None),
     /// Allows `extern "rust-cold"`.
diff --git a/compiler/rustc_feature/src/builtin_attrs.rs b/compiler/rustc_feature/src/builtin_attrs.rs
index c77292fdd16..574419440de 100644
--- a/compiler/rustc_feature/src/builtin_attrs.rs
+++ b/compiler/rustc_feature/src/builtin_attrs.rs
@@ -403,16 +403,16 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         doc, Normal, template!(List: "hidden|inline|...", NameValueStr: "string"), DuplicatesOk
     ),
 
+    // Debugging
+    ungated!(
+        debugger_visualizer, Normal,
+        template!(List: r#"natvis_file = "...", gdb_script_file = "...""#), DuplicatesOk
+    ),
+
     // ==========================================================================
     // Unstable attributes:
     // ==========================================================================
 
-    // RFC #3191: #[debugger_visualizer] support
-    gated!(
-        debugger_visualizer, Normal, template!(List: r#"natvis_file = "...", gdb_script_file = "...""#),
-        DuplicatesOk, experimental!(debugger_visualizer)
-    ),
-
     // Linking:
     gated!(
         naked, Normal, template!(Word), WarnFollowing, @only_local: true,
diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs
index 8f91a96f964..e1c030d3e19 100644
--- a/compiler/rustc_hir/src/lang_items.rs
+++ b/compiler/rustc_hir/src/lang_items.rs
@@ -293,6 +293,8 @@ language_item_table! {
 
     PointerLike,             sym::pointer_like,        pointer_like,               Target::Trait,          GenericRequirement::Exact(0);
 
+    ConstParamTy,            sym::const_param_ty,      const_param_ty_trait,       Target::Trait,          GenericRequirement::Exact(0);
+
     Poll,                    sym::Poll,                poll,                       Target::Enum,           GenericRequirement::None;
     PollReady,               sym::Ready,               poll_ready_variant,         Target::Variant,        GenericRequirement::None;
     PollPending,             sym::Pending,             poll_pending_variant,       Target::Variant,        GenericRequirement::None;
diff --git a/compiler/rustc_hir_analysis/messages.ftl b/compiler/rustc_hir_analysis/messages.ftl
index 5d45d09797b..e4f225bdad7 100644
--- a/compiler/rustc_hir_analysis/messages.ftl
+++ b/compiler/rustc_hir_analysis/messages.ftl
@@ -35,6 +35,10 @@ hir_analysis_field_already_declared =
 
 hir_analysis_expected_used_symbol = expected `used`, `used(compiler)` or `used(linker)`
 
+hir_analysis_const_param_ty_impl_on_non_adt =
+    the trait `ConstParamTy` may not be implemented for this type
+    .label = type is not a structure or enumeration
+
 hir_analysis_ambiguous_lifetime_bound =
     ambiguous lifetime bound, explicit lifetime bound required
 
diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 709dea43d84..6cb008bc5f8 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -56,6 +56,9 @@ use std::slice;
 #[derive(Debug)]
 pub struct PathSeg(pub DefId, pub usize);
 
+#[derive(Copy, Clone, Debug)]
+pub struct OnlySelfBounds(pub bool);
+
 pub trait AstConv<'tcx> {
     fn tcx(&self) -> TyCtxt<'tcx>;
 
@@ -670,6 +673,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         args: &GenericArgs<'_>,
         infer_args: bool,
         self_ty: Ty<'tcx>,
+        only_self_bounds: OnlySelfBounds,
     ) -> GenericArgCountResult {
         let (substs, arg_count) = self.create_substs_for_ast_path(
             trait_ref_span,
@@ -706,6 +710,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 &mut dup_bindings,
                 binding_span.unwrap_or(binding.span),
                 constness,
+                only_self_bounds,
             );
             // Okay to ignore `Err` because of `ErrorGuaranteed` (see above).
         }
@@ -741,6 +746,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         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;
@@ -766,6 +772,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
             args,
             infer_args,
             self_ty,
+            only_self_bounds,
         )
     }
 
@@ -777,6 +784,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         args: &GenericArgs<'_>,
         self_ty: Ty<'tcx>,
         bounds: &mut Bounds<'tcx>,
+        only_self_bounds: OnlySelfBounds,
     ) {
         let binding_span = Some(span);
         let constness = ty::BoundConstness::NotConst;
@@ -799,6 +807,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
             args,
             infer_args,
             self_ty,
+            only_self_bounds,
         );
     }
 
@@ -947,6 +956,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         ast_bounds: I,
         bounds: &mut Bounds<'tcx>,
         bound_vars: &'tcx ty::List<ty::BoundVariableKind>,
+        only_self_bounds: OnlySelfBounds,
     ) {
         for ast_bound in ast_bounds {
             match ast_bound {
@@ -964,11 +974,18 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                         param_ty,
                         bounds,
                         false,
+                        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,
+                        lang_item,
+                        span,
+                        hir_id,
+                        args,
+                        param_ty,
+                        bounds,
+                        only_self_bounds,
                     );
                 }
                 hir::GenericBound::Outlives(lifetime) => {
@@ -1006,8 +1023,19 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         &self,
         param_ty: Ty<'tcx>,
         ast_bounds: &[hir::GenericBound<'_>],
+        only_self_bounds: OnlySelfBounds,
     ) -> Bounds<'tcx> {
-        self.compute_bounds_inner(param_ty, ast_bounds)
+        let mut bounds = Bounds::default();
+        self.add_bounds(
+            param_ty,
+            ast_bounds.iter(),
+            &mut bounds,
+            ty::List::empty(),
+            only_self_bounds,
+        );
+        debug!(?bounds);
+
+        bounds
     }
 
     /// Convert the bounds in `ast_bounds` that refer to traits which define an associated type
@@ -1029,17 +1057,14 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
             }
         }
 
-        self.compute_bounds_inner(param_ty, &result)
-    }
-
-    fn compute_bounds_inner(
-        &self,
-        param_ty: Ty<'tcx>,
-        ast_bounds: &[hir::GenericBound<'_>],
-    ) -> Bounds<'tcx> {
         let mut bounds = Bounds::default();
-
-        self.add_bounds(param_ty, ast_bounds.iter(), &mut bounds, ty::List::empty());
+        self.add_bounds(
+            param_ty,
+            result.iter(),
+            &mut bounds,
+            ty::List::empty(),
+            OnlySelfBounds(true),
+        );
         debug!(?bounds);
 
         bounds
@@ -1062,6 +1087,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         dup_bindings: &mut FxHashMap<DefId, Span>,
         path_span: Span,
         constness: ty::BoundConstness,
+        only_self_bounds: OnlySelfBounds,
     ) -> Result<(), ErrorGuaranteed> {
         // Given something like `U: SomeTrait<T = X>`, we want to produce a
         // predicate like `<U as SomeTrait>::T = X`. This is somewhat
@@ -1361,8 +1387,20 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 //
                 // Calling `skip_binder` is okay, because `add_bounds` expects the `param_ty`
                 // parameter to have a skipped binder.
-                let param_ty = tcx.mk_alias(ty::Projection, projection_ty.skip_binder());
-                self.add_bounds(param_ty, ast_bounds.iter(), bounds, projection_ty.bound_vars());
+                //
+                // NOTE: If `only_self_bounds` is true, do NOT expand this associated
+                // type bound into a trait predicate, since we only want to add predicates
+                // for the `Self` type.
+                if !only_self_bounds.0 {
+                    let param_ty = tcx.mk_alias(ty::Projection, projection_ty.skip_binder());
+                    self.add_bounds(
+                        param_ty,
+                        ast_bounds.iter(),
+                        bounds,
+                        projection_ty.bound_vars(),
+                        only_self_bounds,
+                    );
+                }
             }
         }
         Ok(())
@@ -1403,6 +1441,10 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 dummy_self,
                 &mut bounds,
                 false,
+                // FIXME: This should be `true`, but we don't really handle
+                // associated type bounds or type aliases in objects in a way
+                // that makes this meaningful, I think.
+                OnlySelfBounds(false),
             ) {
                 potential_assoc_types.extend(cur_potential_assoc_types);
             }
diff --git a/compiler/rustc_hir_analysis/src/coherence/builtin.rs b/compiler/rustc_hir_analysis/src/coherence/builtin.rs
index 611ce13b739..0f450ae67b7 100644
--- a/compiler/rustc_hir_analysis/src/coherence/builtin.rs
+++ b/compiler/rustc_hir_analysis/src/coherence/builtin.rs
@@ -1,9 +1,11 @@
 //! Check properties that are required by built-in traits and set
 //! up data structures required by type-checking/codegen.
 
-use crate::errors::{CopyImplOnNonAdt, CopyImplOnTypeWithDtor, DropImplOnWrongItem};
+use crate::errors::{
+    ConstParamTyImplOnNonAdt, CopyImplOnNonAdt, CopyImplOnTypeWithDtor, DropImplOnWrongItem,
+};
 use rustc_data_structures::fx::FxHashSet;
-use rustc_errors::{struct_span_err, MultiSpan};
+use rustc_errors::{struct_span_err, ErrorGuaranteed, MultiSpan};
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::lang_items::LangItem;
@@ -14,9 +16,11 @@ use rustc_infer::infer::{DefineOpaqueTypes, TyCtxtInferExt};
 use rustc_infer::traits::Obligation;
 use rustc_middle::ty::adjustment::CoerceUnsizedInfo;
 use rustc_middle::ty::{self, suggest_constraining_type_params, Ty, TyCtxt, TypeVisitableExt};
+use rustc_span::Span;
 use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
 use rustc_trait_selection::traits::misc::{
-    type_allowed_to_implement_copy, CopyImplementationError, InfringingFieldsReason,
+    type_allowed_to_implement_const_param_ty, type_allowed_to_implement_copy,
+    ConstParamTyImplementationError, CopyImplementationError, InfringingFieldsReason,
 };
 use rustc_trait_selection::traits::ObligationCtxt;
 use rustc_trait_selection::traits::{self, ObligationCause};
@@ -27,6 +31,7 @@ pub fn check_trait(tcx: TyCtxt<'_>, trait_def_id: DefId) {
     Checker { tcx, trait_def_id }
         .check(lang_items.drop_trait(), visit_implementation_of_drop)
         .check(lang_items.copy_trait(), visit_implementation_of_copy)
+        .check(lang_items.const_param_ty_trait(), visit_implementation_of_const_param_ty)
         .check(lang_items.coerce_unsized_trait(), visit_implementation_of_coerce_unsized)
         .check(lang_items.dispatch_from_dyn_trait(), visit_implementation_of_dispatch_from_dyn);
 }
@@ -83,110 +88,7 @@ fn visit_implementation_of_copy(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
     match type_allowed_to_implement_copy(tcx, param_env, self_type, cause) {
         Ok(()) => {}
         Err(CopyImplementationError::InfringingFields(fields)) => {
-            let mut err = struct_span_err!(
-                tcx.sess,
-                span,
-                E0204,
-                "the trait `Copy` cannot be implemented for this type"
-            );
-
-            // We'll try to suggest constraining type parameters to fulfill the requirements of
-            // their `Copy` implementation.
-            let mut errors: BTreeMap<_, Vec<_>> = Default::default();
-            let mut bounds = vec![];
-
-            let mut seen_tys = FxHashSet::default();
-
-            for (field, ty, reason) in fields {
-                // Only report an error once per type.
-                if !seen_tys.insert(ty) {
-                    continue;
-                }
-
-                let field_span = tcx.def_span(field.did);
-                err.span_label(field_span, "this field does not implement `Copy`");
-
-                match reason {
-                    InfringingFieldsReason::Fulfill(fulfillment_errors) => {
-                        for error in fulfillment_errors {
-                            let error_predicate = error.obligation.predicate;
-                            // Only note if it's not the root obligation, otherwise it's trivial and
-                            // should be self-explanatory (i.e. a field literally doesn't implement Copy).
-
-                            // FIXME: This error could be more descriptive, especially if the error_predicate
-                            // contains a foreign type or if it's a deeply nested type...
-                            if error_predicate != error.root_obligation.predicate {
-                                errors
-                                    .entry((ty.to_string(), error_predicate.to_string()))
-                                    .or_default()
-                                    .push(error.obligation.cause.span);
-                            }
-                            if let ty::PredicateKind::Clause(ty::Clause::Trait(
-                                ty::TraitPredicate {
-                                    trait_ref,
-                                    polarity: ty::ImplPolarity::Positive,
-                                    ..
-                                },
-                            )) = error_predicate.kind().skip_binder()
-                            {
-                                let ty = trait_ref.self_ty();
-                                if let ty::Param(_) = ty.kind() {
-                                    bounds.push((
-                                        format!("{ty}"),
-                                        trait_ref.print_only_trait_path().to_string(),
-                                        Some(trait_ref.def_id),
-                                    ));
-                                }
-                            }
-                        }
-                    }
-                    InfringingFieldsReason::Regions(region_errors) => {
-                        for error in region_errors {
-                            let ty = ty.to_string();
-                            match error {
-                                RegionResolutionError::ConcreteFailure(origin, a, b) => {
-                                    let predicate = format!("{b}: {a}");
-                                    errors
-                                        .entry((ty.clone(), predicate.clone()))
-                                        .or_default()
-                                        .push(origin.span());
-                                    if let ty::RegionKind::ReEarlyBound(ebr) = *b && ebr.has_name() {
-                                        bounds.push((b.to_string(), a.to_string(), None));
-                                    }
-                                }
-                                RegionResolutionError::GenericBoundFailure(origin, a, b) => {
-                                    let predicate = format!("{a}: {b}");
-                                    errors
-                                        .entry((ty.clone(), predicate.clone()))
-                                        .or_default()
-                                        .push(origin.span());
-                                    if let infer::region_constraints::GenericKind::Param(_) = a {
-                                        bounds.push((a.to_string(), b.to_string(), None));
-                                    }
-                                }
-                                _ => continue,
-                            }
-                        }
-                    }
-                }
-            }
-            for ((ty, error_predicate), spans) in errors {
-                let span: MultiSpan = spans.into();
-                err.span_note(
-                    span,
-                    &format!("the `Copy` impl for `{}` requires that `{}`", ty, error_predicate),
-                );
-            }
-            suggest_constraining_type_params(
-                tcx,
-                tcx.hir().get_generics(impl_did).expect("impls always have generics"),
-                &mut err,
-                bounds.iter().map(|(param, constraint, def_id)| {
-                    (param.as_str(), constraint.as_str(), *def_id)
-                }),
-                None,
-            );
-            err.emit();
+            infringing_fields_error(tcx, fields, LangItem::Copy, impl_did, span);
         }
         Err(CopyImplementationError::NotAnAdt) => {
             tcx.sess.emit_err(CopyImplOnNonAdt { span });
@@ -197,6 +99,29 @@ fn visit_implementation_of_copy(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
     }
 }
 
+fn visit_implementation_of_const_param_ty(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
+    let self_type = tcx.type_of(impl_did).subst_identity();
+    assert!(!self_type.has_escaping_bound_vars());
+
+    let param_env = tcx.param_env(impl_did);
+
+    let span = match tcx.hir().expect_item(impl_did).expect_impl() {
+        hir::Impl { polarity: hir::ImplPolarity::Negative(_), .. } => return,
+        impl_ => impl_.self_ty.span,
+    };
+
+    let cause = traits::ObligationCause::misc(span, impl_did);
+    match type_allowed_to_implement_const_param_ty(tcx, param_env, self_type, cause) {
+        Ok(()) => {}
+        Err(ConstParamTyImplementationError::InfrigingFields(fields)) => {
+            infringing_fields_error(tcx, fields, LangItem::ConstParamTy, impl_did, span);
+        }
+        Err(ConstParamTyImplementationError::NotAnAdtOrBuiltinAllowed) => {
+            tcx.sess.emit_err(ConstParamTyImplOnNonAdt { span });
+        }
+    }
+}
+
 fn visit_implementation_of_coerce_unsized(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
     debug!("visit_implementation_of_coerce_unsized: impl_did={:?}", impl_did);
 
@@ -593,3 +518,119 @@ pub fn coerce_unsized_info<'tcx>(tcx: TyCtxt<'tcx>, impl_did: LocalDefId) -> Coe
 
     CoerceUnsizedInfo { custom_kind: kind }
 }
+
+fn infringing_fields_error(
+    tcx: TyCtxt<'_>,
+    fields: Vec<(&ty::FieldDef, Ty<'_>, InfringingFieldsReason<'_>)>,
+    lang_item: LangItem,
+    impl_did: LocalDefId,
+    impl_span: Span,
+) -> ErrorGuaranteed {
+    let trait_did = tcx.require_lang_item(lang_item, Some(impl_span));
+
+    let trait_name = tcx.def_path_str(trait_did);
+
+    let mut err = struct_span_err!(
+        tcx.sess,
+        impl_span,
+        E0204,
+        "the trait `{trait_name}` cannot be implemented for this type"
+    );
+
+    // We'll try to suggest constraining type parameters to fulfill the requirements of
+    // their `Copy` implementation.
+    let mut errors: BTreeMap<_, Vec<_>> = Default::default();
+    let mut bounds = vec![];
+
+    let mut seen_tys = FxHashSet::default();
+
+    for (field, ty, reason) in fields {
+        // Only report an error once per type.
+        if !seen_tys.insert(ty) {
+            continue;
+        }
+
+        let field_span = tcx.def_span(field.did);
+        err.span_label(field_span, format!("this field does not implement `{trait_name}`"));
+
+        match reason {
+            InfringingFieldsReason::Fulfill(fulfillment_errors) => {
+                for error in fulfillment_errors {
+                    let error_predicate = error.obligation.predicate;
+                    // Only note if it's not the root obligation, otherwise it's trivial and
+                    // should be self-explanatory (i.e. a field literally doesn't implement Copy).
+
+                    // FIXME: This error could be more descriptive, especially if the error_predicate
+                    // contains a foreign type or if it's a deeply nested type...
+                    if error_predicate != error.root_obligation.predicate {
+                        errors
+                            .entry((ty.to_string(), error_predicate.to_string()))
+                            .or_default()
+                            .push(error.obligation.cause.span);
+                    }
+                    if let ty::PredicateKind::Clause(ty::Clause::Trait(ty::TraitPredicate {
+                        trait_ref,
+                        polarity: ty::ImplPolarity::Positive,
+                        ..
+                    })) = error_predicate.kind().skip_binder()
+                    {
+                        let ty = trait_ref.self_ty();
+                        if let ty::Param(_) = ty.kind() {
+                            bounds.push((
+                                format!("{ty}"),
+                                trait_ref.print_only_trait_path().to_string(),
+                                Some(trait_ref.def_id),
+                            ));
+                        }
+                    }
+                }
+            }
+            InfringingFieldsReason::Regions(region_errors) => {
+                for error in region_errors {
+                    let ty = ty.to_string();
+                    match error {
+                        RegionResolutionError::ConcreteFailure(origin, a, b) => {
+                            let predicate = format!("{b}: {a}");
+                            errors
+                                .entry((ty.clone(), predicate.clone()))
+                                .or_default()
+                                .push(origin.span());
+                            if let ty::RegionKind::ReEarlyBound(ebr) = *b && ebr.has_name() {
+                                        bounds.push((b.to_string(), a.to_string(), None));
+                                    }
+                        }
+                        RegionResolutionError::GenericBoundFailure(origin, a, b) => {
+                            let predicate = format!("{a}: {b}");
+                            errors
+                                .entry((ty.clone(), predicate.clone()))
+                                .or_default()
+                                .push(origin.span());
+                            if let infer::region_constraints::GenericKind::Param(_) = a {
+                                bounds.push((a.to_string(), b.to_string(), None));
+                            }
+                        }
+                        _ => continue,
+                    }
+                }
+            }
+        }
+    }
+    for ((ty, error_predicate), spans) in errors {
+        let span: MultiSpan = spans.into();
+        err.span_note(
+            span,
+            format!("the `{trait_name}` impl for `{ty}` requires that `{error_predicate}`"),
+        );
+    }
+    suggest_constraining_type_params(
+        tcx,
+        tcx.hir().get_generics(impl_did).expect("impls always have generics"),
+        &mut err,
+        bounds
+            .iter()
+            .map(|(param, constraint, def_id)| (param.as_str(), constraint.as_str(), *def_id)),
+        None,
+    );
+
+    err.emit()
+}
diff --git a/compiler/rustc_hir_analysis/src/collect/item_bounds.rs b/compiler/rustc_hir_analysis/src/collect/item_bounds.rs
index 80d6bc7db9e..948b903e509 100644
--- a/compiler/rustc_hir_analysis/src/collect/item_bounds.rs
+++ b/compiler/rustc_hir_analysis/src/collect/item_bounds.rs
@@ -1,5 +1,5 @@
 use super::ItemCtxt;
-use crate::astconv::AstConv;
+use crate::astconv::{AstConv, OnlySelfBounds};
 use rustc_hir as hir;
 use rustc_infer::traits::util;
 use rustc_middle::ty::subst::InternalSubsts;
@@ -26,7 +26,7 @@ fn associated_type_bounds<'tcx>(
     );
 
     let icx = ItemCtxt::new(tcx, assoc_item_def_id);
-    let mut bounds = icx.astconv().compute_bounds(item_ty, ast_bounds);
+    let mut bounds = icx.astconv().compute_bounds(item_ty, ast_bounds, OnlySelfBounds(false));
     // Associated types are implicitly sized unless a `?Sized` bound is found
     icx.astconv().add_implicitly_sized(&mut bounds, item_ty, ast_bounds, None, span);
 
@@ -67,7 +67,7 @@ fn opaque_type_bounds<'tcx>(
 ) -> &'tcx [(ty::Predicate<'tcx>, Span)] {
     ty::print::with_no_queries!({
         let icx = ItemCtxt::new(tcx, opaque_def_id);
-        let mut bounds = icx.astconv().compute_bounds(item_ty, ast_bounds);
+        let mut bounds = icx.astconv().compute_bounds(item_ty, ast_bounds, OnlySelfBounds(false));
         // Opaque types are implicitly sized unless a `?Sized` bound is found
         icx.astconv().add_implicitly_sized(&mut bounds, item_ty, ast_bounds, None, span);
         debug!(?bounds);
diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
index 8c414521b76..83470342a76 100644
--- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
@@ -1,4 +1,4 @@
-use crate::astconv::AstConv;
+use crate::astconv::{AstConv, OnlySelfBounds};
 use crate::bounds::Bounds;
 use crate::collect::ItemCtxt;
 use crate::constrained_generic_params as cgp;
@@ -14,9 +14,6 @@ use rustc_middle::ty::{GenericPredicates, ToPredicate};
 use rustc_span::symbol::{sym, Ident};
 use rustc_span::{Span, DUMMY_SP};
 
-#[derive(Debug)]
-struct OnlySelfBounds(bool);
-
 /// Returns a list of all type predicates (explicit and implicit) for the definition with
 /// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
 /// `Self: Trait` predicates for traits.
@@ -99,8 +96,9 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
             | ItemKind::Struct(_, generics)
             | ItemKind::Union(_, generics) => generics,
 
-            ItemKind::Trait(_, _, generics, ..) | ItemKind::TraitAlias(generics, _) => {
-                is_trait = Some(ty::TraitRef::identity(tcx, def_id.to_def_id()));
+            ItemKind::Trait(_, _, generics, self_bounds, ..)
+            | ItemKind::TraitAlias(generics, self_bounds) => {
+                is_trait = Some(self_bounds);
                 generics
             }
             ItemKind::OpaqueTy(OpaqueTy { generics, .. }) => generics,
@@ -122,10 +120,14 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
 
     // Below we'll consider the bounds on the type parameters (including `Self`)
     // and the explicit where-clauses, but to get the full set of predicates
-    // on a trait we need to add in the supertrait bounds and bounds found on
-    // associated types.
-    if let Some(_trait_ref) = is_trait {
-        predicates.extend(tcx.implied_predicates_of(def_id).predicates.iter().cloned());
+    // on a trait we must also consider the bounds that follow the trait's name,
+    // like `trait Foo: A + B + C`.
+    if let Some(self_bounds) = is_trait {
+        predicates.extend(
+            icx.astconv()
+                .compute_bounds(tcx.types.self_param, self_bounds, OnlySelfBounds(false))
+                .predicates(),
+        );
     }
 
     // In default impls, we can assume that the self type implements
@@ -225,7 +227,13 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
                 }
 
                 let mut bounds = Bounds::default();
-                icx.astconv().add_bounds(ty, bound_pred.bounds.iter(), &mut bounds, bound_vars);
+                icx.astconv().add_bounds(
+                    ty,
+                    bound_pred.bounds.iter(),
+                    &mut bounds,
+                    bound_vars,
+                    OnlySelfBounds(false),
+                );
                 predicates.extend(bounds.predicates());
             }
 
@@ -608,7 +616,7 @@ pub(super) fn implied_predicates_with_filter(
     let (superbounds, where_bounds_that_match) = match filter {
         PredicateFilter::All => (
             // Convert the bounds that follow the colon (or equal in trait aliases)
-            icx.astconv().compute_bounds(self_param_ty, bounds),
+            icx.astconv().compute_bounds(self_param_ty, bounds, OnlySelfBounds(false)),
             // Also include all where clause bounds
             icx.type_parameter_bounds_in_generics(
                 generics,
@@ -620,7 +628,7 @@ pub(super) fn implied_predicates_with_filter(
         ),
         PredicateFilter::SelfOnly => (
             // Convert the bounds that follow the colon (or equal in trait aliases)
-            icx.astconv().compute_bounds(self_param_ty, bounds),
+            icx.astconv().compute_bounds(self_param_ty, bounds, OnlySelfBounds(true)),
             // Include where clause bounds for `Self`
             icx.type_parameter_bounds_in_generics(
                 generics,
@@ -774,32 +782,35 @@ impl<'tcx> ItemCtxt<'tcx> {
         only_self_bounds: OnlySelfBounds,
         assoc_name: Option<Ident>,
     ) -> Vec<(ty::Predicate<'tcx>, Span)> {
-        ast_generics
-            .predicates
-            .iter()
-            .filter_map(|wp| match wp {
-                hir::WherePredicate::BoundPredicate(bp) => Some(bp),
-                _ => None,
-            })
-            .flat_map(|bp| {
-                let bt = if bp.is_param_bound(param_def_id.to_def_id()) {
-                    Some(ty)
-                } else if !only_self_bounds.0 {
-                    Some(self.to_ty(bp.bounded_ty))
-                } else {
-                    None
-                };
-                let bvars = self.tcx.late_bound_vars(bp.hir_id);
-
-                bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b, bvars))).filter(
-                    |(_, b, _)| match assoc_name {
-                        Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
-                        None => true,
-                    },
-                )
-            })
-            .flat_map(|(bt, b, bvars)| predicates_from_bound(self, bt, b, bvars))
-            .collect()
+        let mut bounds = Bounds::default();
+
+        for predicate in ast_generics.predicates {
+            let hir::WherePredicate::BoundPredicate(predicate) = predicate else {
+                continue;
+            };
+
+            let bound_ty = if predicate.is_param_bound(param_def_id.to_def_id()) {
+                ty
+            } else if !only_self_bounds.0 {
+                self.to_ty(predicate.bounded_ty)
+            } else {
+                continue;
+            };
+
+            let bound_vars = self.tcx.late_bound_vars(predicate.hir_id);
+            self.astconv().add_bounds(
+                bound_ty,
+                predicate.bounds.iter().filter(|bound| {
+                    assoc_name
+                        .map_or(true, |assoc_name| self.bound_defines_assoc_item(bound, assoc_name))
+                }),
+                &mut bounds,
+                bound_vars,
+                only_self_bounds,
+            );
+        }
+
+        bounds.predicates().collect()
     }
 
     #[instrument(level = "trace", skip(self))]
@@ -817,19 +828,3 @@ impl<'tcx> ItemCtxt<'tcx> {
         }
     }
 }
-
-/// Converts a specific `GenericBound` from the AST into a set of
-/// predicates that apply to the self type. A vector is returned
-/// because this can be anywhere from zero predicates (`T: ?Sized` adds no
-/// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
-/// and `<T as Bar>::X == i32`).
-fn predicates_from_bound<'tcx>(
-    astconv: &dyn AstConv<'tcx>,
-    param_ty: Ty<'tcx>,
-    bound: &'tcx hir::GenericBound<'tcx>,
-    bound_vars: &'tcx ty::List<ty::BoundVariableKind>,
-) -> Vec<(ty::Predicate<'tcx>, Span)> {
-    let mut bounds = Bounds::default();
-    astconv.add_bounds(param_ty, [bound].into_iter(), &mut bounds, bound_vars);
-    bounds.predicates().collect()
-}
diff --git a/compiler/rustc_hir_analysis/src/errors.rs b/compiler/rustc_hir_analysis/src/errors.rs
index f82169dee98..25ad1bed763 100644
--- a/compiler/rustc_hir_analysis/src/errors.rs
+++ b/compiler/rustc_hir_analysis/src/errors.rs
@@ -108,6 +108,14 @@ pub struct CopyImplOnNonAdt {
 }
 
 #[derive(Diagnostic)]
+#[diag(hir_analysis_const_param_ty_impl_on_non_adt)]
+pub struct ConstParamTyImplOnNonAdt {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
 #[diag(hir_analysis_trait_object_declared_with_no_traits, code = "E0224")]
 pub struct TraitObjectDeclaredWithNoTraits {
     #[primary_span]
diff --git a/compiler/rustc_hir_analysis/src/lib.rs b/compiler/rustc_hir_analysis/src/lib.rs
index a4b797f77f7..961457b7579 100644
--- a/compiler/rustc_hir_analysis/src/lib.rs
+++ b/compiler/rustc_hir_analysis/src/lib.rs
@@ -116,7 +116,7 @@ use rustc_trait_selection::traits::{self, ObligationCause, ObligationCauseCode,
 
 use std::ops::Not;
 
-use astconv::AstConv;
+use astconv::{AstConv, OnlySelfBounds};
 use bounds::Bounds;
 
 fluent_messages! { "../messages.ftl" }
@@ -531,6 +531,7 @@ pub fn hir_trait_to_predicates<'tcx>(
         self_ty,
         &mut bounds,
         true,
+        OnlySelfBounds(false),
     );
 
     bounds
diff --git a/compiler/rustc_lint/messages.ftl b/compiler/rustc_lint/messages.ftl
index 3c6dbb466db..71cf644eb50 100644
--- a/compiler/rustc_lint/messages.ftl
+++ b/compiler/rustc_lint/messages.ftl
@@ -50,6 +50,14 @@ lint_deprecated_lint_name =
 lint_renamed_or_removed_lint = {$msg}
     .suggestion = use the new name
 
+lint_suspicious_double_ref_op =
+    using `.{$call}()` on a double reference, which returns `{$ty}` instead of {$op ->
+        *[should_not_happen] [{$op}]
+        [deref] dereferencing
+        [borrow] borrowing
+        [clone] cloning
+    } the inner type
+
 lint_unknown_lint =
     unknown lint: `{$name}`
     .suggestion = did you mean
diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs
index 848f6a9ecb5..d7bacc6485f 100644
--- a/compiler/rustc_lint/src/lints.rs
+++ b/compiler/rustc_lint/src/lints.rs
@@ -1150,6 +1150,14 @@ pub struct NoopMethodCallDiag<'a> {
     pub label: Span,
 }
 
+#[derive(LintDiagnostic)]
+#[diag(lint_suspicious_double_ref_op)]
+pub struct SuspiciousDoubleRefDiag<'a> {
+    pub call: Symbol,
+    pub ty: Ty<'a>,
+    pub op: &'static str,
+}
+
 // pass_by_value.rs
 #[derive(LintDiagnostic)]
 #[diag(lint_pass_by_value)]
diff --git a/compiler/rustc_lint/src/noop_method_call.rs b/compiler/rustc_lint/src/noop_method_call.rs
index d67a00619dd..d054966459d 100644
--- a/compiler/rustc_lint/src/noop_method_call.rs
+++ b/compiler/rustc_lint/src/noop_method_call.rs
@@ -1,10 +1,11 @@
 use crate::context::LintContext;
-use crate::lints::NoopMethodCallDiag;
+use crate::lints::{NoopMethodCallDiag, SuspiciousDoubleRefDiag};
 use crate::LateContext;
 use crate::LateLintPass;
 use rustc_hir::def::DefKind;
 use rustc_hir::{Expr, ExprKind};
 use rustc_middle::ty;
+use rustc_middle::ty::adjustment::Adjust;
 use rustc_span::symbol::sym;
 
 declare_lint! {
@@ -35,14 +36,44 @@ declare_lint! {
     "detects the use of well-known noop methods"
 }
 
-declare_lint_pass!(NoopMethodCall => [NOOP_METHOD_CALL]);
+declare_lint! {
+    /// The `suspicious_double_ref_op` lint checks for usage of `.clone()`/`.borrow()`/`.deref()`
+    /// on an `&&T` when `T: !Deref/Borrow/Clone`, which means the call will return the inner `&T`,
+    /// instead of performing the operation on the underlying `T` and can be confusing.
+    ///
+    /// ### Example
+    ///
+    /// ```rust
+    /// # #![allow(unused)]
+    /// struct Foo;
+    /// let foo = &&Foo;
+    /// let clone: &Foo = foo.clone();
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// Since `Foo` doesn't implement `Clone`, running `.clone()` only dereferences the double
+    /// reference, instead of cloning the inner type which should be what was intended.
+    pub SUSPICIOUS_DOUBLE_REF_OP,
+    Warn,
+    "suspicious call of trait method on `&&T`"
+}
+
+declare_lint_pass!(NoopMethodCall => [NOOP_METHOD_CALL, SUSPICIOUS_DOUBLE_REF_OP]);
 
 impl<'tcx> LateLintPass<'tcx> for NoopMethodCall {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         // We only care about method calls.
-        let ExprKind::MethodCall(call, receiver, ..) = &expr.kind else {
-            return
+        let ExprKind::MethodCall(call, receiver, _, call_span) = &expr.kind else {
+            return;
         };
+
+        if call_span.from_expansion() {
+            return;
+        }
+
         // We only care about method calls corresponding to the `Clone`, `Deref` and `Borrow`
         // traits and ignore any other method call.
         let did = match cx.typeck_results().type_dependent_def(expr.hir_id) {
@@ -70,25 +101,39 @@ impl<'tcx> LateLintPass<'tcx> for NoopMethodCall {
         };
         // (Re)check that it implements the noop diagnostic.
         let Some(name) = cx.tcx.get_diagnostic_name(i.def_id()) else { return };
-        if !matches!(
-            name,
-            sym::noop_method_borrow | sym::noop_method_clone | sym::noop_method_deref
-        ) {
-            return;
-        }
+
+        let op = match name {
+            sym::noop_method_borrow => "borrow",
+            sym::noop_method_clone => "clone",
+            sym::noop_method_deref => "deref",
+            _ => return,
+        };
+
         let receiver_ty = cx.typeck_results().expr_ty(receiver);
         let expr_ty = cx.typeck_results().expr_ty_adjusted(expr);
-        if receiver_ty != expr_ty {
-            // This lint will only trigger if the receiver type and resulting expression \
-            // type are the same, implying that the method call is unnecessary.
+        let arg_adjustments = cx.typeck_results().expr_adjustments(receiver);
+
+        // If there is any user defined auto-deref step, then we don't want to warn.
+        // https://github.com/rust-lang/rust-clippy/issues/9272
+        if arg_adjustments.iter().any(|adj| matches!(adj.kind, Adjust::Deref(Some(_)))) {
             return;
         }
+
         let expr_span = expr.span;
         let span = expr_span.with_lo(receiver.span.hi());
-        cx.emit_spanned_lint(
-            NOOP_METHOD_CALL,
-            span,
-            NoopMethodCallDiag { method: call.ident.name, receiver_ty, label: span },
-        );
+
+        if receiver_ty == expr_ty {
+            cx.emit_spanned_lint(
+                NOOP_METHOD_CALL,
+                span,
+                NoopMethodCallDiag { method: call.ident.name, receiver_ty, label: span },
+            );
+        } else {
+            cx.emit_spanned_lint(
+                SUSPICIOUS_DOUBLE_REF_OP,
+                span,
+                SuspiciousDoubleRefDiag { call: call.ident.name, ty: expr_ty, op },
+            )
+        }
     }
 }
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 31bbdb2a3bc..7969b848fd9 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -531,6 +531,7 @@ symbols! {
         const_mut_refs,
         const_panic,
         const_panic_fmt,
+        const_param_ty,
         const_precise_live_drops,
         const_raw_ptr_deref,
         const_raw_ptr_to_usize_cast,
diff --git a/compiler/rustc_trait_selection/src/traits/misc.rs b/compiler/rustc_trait_selection/src/traits/misc.rs
index 63949843aed..2210ef975e6 100644
--- a/compiler/rustc_trait_selection/src/traits/misc.rs
+++ b/compiler/rustc_trait_selection/src/traits/misc.rs
@@ -2,13 +2,14 @@
 
 use crate::traits::{self, ObligationCause, ObligationCtxt};
 
+use hir::LangItem;
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_hir as hir;
 use rustc_infer::infer::canonical::Canonical;
 use rustc_infer::infer::{RegionResolutionError, TyCtxtInferExt};
 use rustc_infer::traits::query::NoSolution;
 use rustc_infer::{infer::outlives::env::OutlivesEnvironment, traits::FulfillmentError};
-use rustc_middle::ty::{self, ParamEnv, Ty, TyCtxt, TypeVisitableExt};
+use rustc_middle::ty::{self, AdtDef, GenericArg, List, ParamEnv, Ty, TyCtxt, TypeVisitableExt};
 use rustc_span::DUMMY_SP;
 
 use super::outlives_bounds::InferCtxtExt;
@@ -19,6 +20,11 @@ pub enum CopyImplementationError<'tcx> {
     HasDestructor,
 }
 
+pub enum ConstParamTyImplementationError<'tcx> {
+    InfrigingFields(Vec<(&'tcx ty::FieldDef, Ty<'tcx>, InfringingFieldsReason<'tcx>)>),
+    NotAnAdtOrBuiltinAllowed,
+}
+
 pub enum InfringingFieldsReason<'tcx> {
     Fulfill(Vec<FulfillmentError<'tcx>>),
     Regions(Vec<RegionResolutionError<'tcx>>),
@@ -27,7 +33,10 @@ pub enum InfringingFieldsReason<'tcx> {
 /// Checks that the fields of the type (an ADT) all implement copy.
 ///
 /// If fields don't implement copy, return an error containing a list of
-/// those violating fields. If it's not an ADT, returns `Err(NotAnAdt)`.
+/// those violating fields.
+///
+/// If it's not an ADT, int ty, `bool`, float ty, `char`, raw pointer, `!`,
+/// a reference or an array returns `Err(NotAnAdt)`.
 pub fn type_allowed_to_implement_copy<'tcx>(
     tcx: TyCtxt<'tcx>,
     param_env: ty::ParamEnv<'tcx>,
@@ -47,12 +56,82 @@ pub fn type_allowed_to_implement_copy<'tcx>(
         | ty::Ref(_, _, hir::Mutability::Not)
         | ty::Array(..) => return Ok(()),
 
-        ty::Adt(adt, substs) => (adt, substs),
+        &ty::Adt(adt, substs) => (adt, substs),
 
         _ => return Err(CopyImplementationError::NotAnAdt),
     };
 
-    let copy_def_id = tcx.require_lang_item(hir::LangItem::Copy, Some(parent_cause.span));
+    all_fields_implement_trait(
+        tcx,
+        param_env,
+        self_type,
+        adt,
+        substs,
+        parent_cause,
+        hir::LangItem::Copy,
+    )
+    .map_err(CopyImplementationError::InfringingFields)?;
+
+    if adt.has_dtor(tcx) {
+        return Err(CopyImplementationError::HasDestructor);
+    }
+
+    Ok(())
+}
+
+/// Checks that the fields of the type (an ADT) all implement `ConstParamTy`.
+///
+/// If fields don't implement `ConstParamTy`, return an error containing a list of
+/// those violating fields.
+///
+/// If it's not an ADT, int ty, `bool` or `char`, returns `Err(NotAnAdtOrBuiltinAllowed)`.
+pub fn type_allowed_to_implement_const_param_ty<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    param_env: ty::ParamEnv<'tcx>,
+    self_type: Ty<'tcx>,
+    parent_cause: ObligationCause<'tcx>,
+) -> Result<(), ConstParamTyImplementationError<'tcx>> {
+    let (adt, substs) = match self_type.kind() {
+        // `core` provides these impls.
+        ty::Uint(_)
+        | ty::Int(_)
+        | ty::Bool
+        | ty::Char
+        | ty::Str
+        | ty::Array(..)
+        | ty::Slice(_)
+        | ty::Ref(.., hir::Mutability::Not) => return Ok(()),
+
+        &ty::Adt(adt, substs) => (adt, substs),
+
+        _ => return Err(ConstParamTyImplementationError::NotAnAdtOrBuiltinAllowed),
+    };
+
+    all_fields_implement_trait(
+        tcx,
+        param_env,
+        self_type,
+        adt,
+        substs,
+        parent_cause,
+        hir::LangItem::ConstParamTy,
+    )
+    .map_err(ConstParamTyImplementationError::InfrigingFields)?;
+
+    Ok(())
+}
+
+/// Check that all fields of a given `adt` implement `lang_item` trait.
+pub fn all_fields_implement_trait<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    param_env: ty::ParamEnv<'tcx>,
+    self_type: Ty<'tcx>,
+    adt: AdtDef<'tcx>,
+    substs: &'tcx List<GenericArg<'tcx>>,
+    parent_cause: ObligationCause<'tcx>,
+    lang_item: LangItem,
+) -> Result<(), Vec<(&'tcx ty::FieldDef, Ty<'tcx>, InfringingFieldsReason<'tcx>)>> {
+    let trait_def_id = tcx.require_lang_item(lang_item, Some(parent_cause.span));
 
     let mut infringing = Vec::new();
     for variant in adt.variants() {
@@ -93,7 +172,7 @@ pub fn type_allowed_to_implement_copy<'tcx>(
             // between expected and found const-generic types. Don't report an
             // additional copy error here, since it's not typically useful.
             if !normalization_errors.is_empty() || ty.references_error() {
-                tcx.sess.delay_span_bug(field_span, format!("couldn't normalize struct field `{unnormalized_ty}` when checking Copy implementation"));
+                tcx.sess.delay_span_bug(field_span, format!("couldn't normalize struct field `{unnormalized_ty}` when checking {tr} implementation", tr = tcx.def_path_str(trait_def_id)));
                 continue;
             }
 
@@ -101,7 +180,7 @@ pub fn type_allowed_to_implement_copy<'tcx>(
                 ObligationCause::dummy_with_span(field_ty_span),
                 param_env,
                 ty,
-                copy_def_id,
+                trait_def_id,
             );
             let errors = ocx.select_all_or_error();
             if !errors.is_empty() {
@@ -124,15 +203,7 @@ pub fn type_allowed_to_implement_copy<'tcx>(
         }
     }
 
-    if !infringing.is_empty() {
-        return Err(CopyImplementationError::InfringingFields(infringing));
-    }
-
-    if adt.has_dtor(tcx) {
-        return Err(CopyImplementationError::HasDestructor);
-    }
-
-    Ok(())
+    if infringing.is_empty() { Ok(()) } else { Err(infringing) }
 }
 
 pub fn check_tys_might_be_eq<'tcx>(
diff --git a/library/core/src/ascii.rs b/library/core/src/ascii.rs
index 8a4cb78cc7f..065f1b3e70e 100644
--- a/library/core/src/ascii.rs
+++ b/library/core/src/ascii.rs
@@ -9,10 +9,10 @@
 
 #![stable(feature = "core_ascii", since = "1.26.0")]
 
+use crate::escape;
 use crate::fmt;
 use crate::iter::FusedIterator;
-use crate::ops::Range;
-use crate::str::from_utf8_unchecked;
+use crate::num::NonZeroUsize;
 
 /// An iterator over the escaped version of a byte.
 ///
@@ -21,10 +21,7 @@ use crate::str::from_utf8_unchecked;
 #[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[derive(Clone)]
-pub struct EscapeDefault {
-    range: Range<u8>,
-    data: [u8; 4],
-}
+pub struct EscapeDefault(escape::EscapeIterInner<4>);
 
 /// Returns an iterator that produces an escaped version of a `u8`.
 ///
@@ -90,21 +87,9 @@ pub struct EscapeDefault {
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn escape_default(c: u8) -> EscapeDefault {
-    let (data, len) = match c {
-        b'\t' => ([b'\\', b't', 0, 0], 2),
-        b'\r' => ([b'\\', b'r', 0, 0], 2),
-        b'\n' => ([b'\\', b'n', 0, 0], 2),
-        b'\\' => ([b'\\', b'\\', 0, 0], 2),
-        b'\'' => ([b'\\', b'\'', 0, 0], 2),
-        b'"' => ([b'\\', b'"', 0, 0], 2),
-        b'\x20'..=b'\x7e' => ([c, 0, 0, 0], 1),
-        _ => {
-            let hex_digits: &[u8; 16] = b"0123456789abcdef";
-            ([b'\\', b'x', hex_digits[(c >> 4) as usize], hex_digits[(c & 0xf) as usize]], 4)
-        }
-    };
-
-    return EscapeDefault { range: 0..len, data };
+    let mut data = [0; 4];
+    let range = escape::escape_ascii_into(&mut data, c);
+    EscapeDefault(escape::EscapeIterInner::new(data, range))
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -113,33 +98,59 @@ impl Iterator for EscapeDefault {
 
     #[inline]
     fn next(&mut self) -> Option<u8> {
-        self.range.next().map(|i| self.data[i as usize])
+        self.0.next()
     }
+
+    #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
-        self.range.size_hint()
+        let n = self.0.len();
+        (n, Some(n))
+    }
+
+    #[inline]
+    fn count(self) -> usize {
+        self.0.len()
     }
+
+    #[inline]
     fn last(mut self) -> Option<u8> {
-        self.next_back()
+        self.0.next_back()
+    }
+
+    #[inline]
+    fn advance_by(&mut self, n: usize) -> Result<(), NonZeroUsize> {
+        self.0.advance_by(n)
     }
 }
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl DoubleEndedIterator for EscapeDefault {
+    #[inline]
     fn next_back(&mut self) -> Option<u8> {
-        self.range.next_back().map(|i| self.data[i as usize])
+        self.0.next_back()
+    }
+
+    #[inline]
+    fn advance_back_by(&mut self, n: usize) -> Result<(), NonZeroUsize> {
+        self.0.advance_back_by(n)
     }
 }
+
 #[stable(feature = "rust1", since = "1.0.0")]
-impl ExactSizeIterator for EscapeDefault {}
+impl ExactSizeIterator for EscapeDefault {
+    #[inline]
+    fn len(&self) -> usize {
+        self.0.len()
+    }
+}
+
 #[stable(feature = "fused", since = "1.26.0")]
 impl FusedIterator for EscapeDefault {}
 
 #[stable(feature = "ascii_escape_display", since = "1.39.0")]
 impl fmt::Display for EscapeDefault {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        // SAFETY: ok because `escape_default` created only valid utf-8 data
-        f.write_str(unsafe {
-            from_utf8_unchecked(&self.data[(self.range.start as usize)..(self.range.end as usize)])
-        })
+        f.write_str(self.0.as_str())
     }
 }
 
diff --git a/library/core/src/char/methods.rs b/library/core/src/char/methods.rs
index 9bc97ea0bff..2408f178075 100644
--- a/library/core/src/char/methods.rs
+++ b/library/core/src/char/methods.rs
@@ -380,20 +380,7 @@ impl char {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn escape_unicode(self) -> EscapeUnicode {
-        let c = self as u32;
-
-        // or-ing 1 ensures that for c==0 the code computes that one
-        // digit should be printed and (which is the same) avoids the
-        // (31 - 32) underflow
-        let msb = 31 - (c | 1).leading_zeros();
-
-        // the index of the most significant hex digit
-        let ms_hex_digit = msb / 4;
-        EscapeUnicode {
-            c: self,
-            state: EscapeUnicodeState::Backslash,
-            hex_digit_idx: ms_hex_digit as usize,
-        }
+        EscapeUnicode::new(self)
     }
 
     /// An extended version of `escape_debug` that optionally permits escaping
@@ -403,21 +390,20 @@ impl char {
     /// characters, and double quotes in strings.
     #[inline]
     pub(crate) fn escape_debug_ext(self, args: EscapeDebugExtArgs) -> EscapeDebug {
-        let init_state = match self {
-            '\0' => EscapeDefaultState::Backslash('0'),
-            '\t' => EscapeDefaultState::Backslash('t'),
-            '\r' => EscapeDefaultState::Backslash('r'),
-            '\n' => EscapeDefaultState::Backslash('n'),
-            '\\' => EscapeDefaultState::Backslash(self),
-            '"' if args.escape_double_quote => EscapeDefaultState::Backslash(self),
-            '\'' if args.escape_single_quote => EscapeDefaultState::Backslash(self),
+        match self {
+            '\0' => EscapeDebug::backslash(b'0'),
+            '\t' => EscapeDebug::backslash(b't'),
+            '\r' => EscapeDebug::backslash(b'r'),
+            '\n' => EscapeDebug::backslash(b'n'),
+            '\\' => EscapeDebug::backslash(b'\\'),
+            '"' if args.escape_double_quote => EscapeDebug::backslash(b'"'),
+            '\'' if args.escape_single_quote => EscapeDebug::backslash(b'\''),
             _ if args.escape_grapheme_extended && self.is_grapheme_extended() => {
-                EscapeDefaultState::Unicode(self.escape_unicode())
+                EscapeDebug::from_unicode(self.escape_unicode())
             }
-            _ if is_printable(self) => EscapeDefaultState::Char(self),
-            _ => EscapeDefaultState::Unicode(self.escape_unicode()),
-        };
-        EscapeDebug(EscapeDefault { state: init_state })
+            _ if is_printable(self) => EscapeDebug::printable(self),
+            _ => EscapeDebug::from_unicode(self.escape_unicode()),
+        }
     }
 
     /// Returns an iterator that yields the literal escape code of a character
@@ -515,15 +501,14 @@ impl char {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn escape_default(self) -> EscapeDefault {
-        let init_state = match self {
-            '\t' => EscapeDefaultState::Backslash('t'),
-            '\r' => EscapeDefaultState::Backslash('r'),
-            '\n' => EscapeDefaultState::Backslash('n'),
-            '\\' | '\'' | '"' => EscapeDefaultState::Backslash(self),
-            '\x20'..='\x7e' => EscapeDefaultState::Char(self),
-            _ => EscapeDefaultState::Unicode(self.escape_unicode()),
-        };
-        EscapeDefault { state: init_state }
+        match self {
+            '\t' => EscapeDefault::backslash(b't'),
+            '\r' => EscapeDefault::backslash(b'r'),
+            '\n' => EscapeDefault::backslash(b'n'),
+            '\\' | '\'' | '"' => EscapeDefault::backslash(self as u8),
+            '\x20'..='\x7e' => EscapeDefault::printable(self as u8),
+            _ => EscapeDefault::from_unicode(self.escape_unicode()),
+        }
     }
 
     /// Returns the number of bytes this `char` would need if encoded in UTF-8.
diff --git a/library/core/src/char/mod.rs b/library/core/src/char/mod.rs
index 8ec78e88733..e186db7052c 100644
--- a/library/core/src/char/mod.rs
+++ b/library/core/src/char/mod.rs
@@ -39,8 +39,10 @@ pub use self::methods::encode_utf16_raw;
 pub use self::methods::encode_utf8_raw;
 
 use crate::error::Error;
+use crate::escape;
 use crate::fmt::{self, Write};
 use crate::iter::FusedIterator;
+use crate::num::NonZeroUsize;
 
 pub(crate) use self::methods::EscapeDebugExtArgs;
 
@@ -146,86 +148,44 @@ pub const fn from_digit(num: u32, radix: u32) -> Option<char> {
 /// [`escape_unicode`]: char::escape_unicode
 #[derive(Clone, Debug)]
 #[stable(feature = "rust1", since = "1.0.0")]
-pub struct EscapeUnicode {
-    c: char,
-    state: EscapeUnicodeState,
-
-    // The index of the next hex digit to be printed (0 if none),
-    // i.e., the number of remaining hex digits to be printed;
-    // increasing from the least significant digit: 0x543210
-    hex_digit_idx: usize,
-}
+pub struct EscapeUnicode(escape::EscapeIterInner<10>);
 
-// The enum values are ordered so that their representation is the
-// same as the remaining length (besides the hexadecimal digits). This
-// likely makes `len()` a single load from memory) and inline-worth.
-#[derive(Clone, Debug)]
-enum EscapeUnicodeState {
-    Done,
-    RightBrace,
-    Value,
-    LeftBrace,
-    Type,
-    Backslash,
+impl EscapeUnicode {
+    fn new(chr: char) -> Self {
+        let mut data = [0; 10];
+        let range = escape::escape_unicode_into(&mut data, chr);
+        Self(escape::EscapeIterInner::new(data, range))
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Iterator for EscapeUnicode {
     type Item = char;
 
+    #[inline]
     fn next(&mut self) -> Option<char> {
-        match self.state {
-            EscapeUnicodeState::Backslash => {
-                self.state = EscapeUnicodeState::Type;
-                Some('\\')
-            }
-            EscapeUnicodeState::Type => {
-                self.state = EscapeUnicodeState::LeftBrace;
-                Some('u')
-            }
-            EscapeUnicodeState::LeftBrace => {
-                self.state = EscapeUnicodeState::Value;
-                Some('{')
-            }
-            EscapeUnicodeState::Value => {
-                let hex_digit = ((self.c as u32) >> (self.hex_digit_idx * 4)) & 0xf;
-                let c = char::from_digit(hex_digit, 16).unwrap();
-                if self.hex_digit_idx == 0 {
-                    self.state = EscapeUnicodeState::RightBrace;
-                } else {
-                    self.hex_digit_idx -= 1;
-                }
-                Some(c)
-            }
-            EscapeUnicodeState::RightBrace => {
-                self.state = EscapeUnicodeState::Done;
-                Some('}')
-            }
-            EscapeUnicodeState::Done => None,
-        }
+        self.0.next().map(char::from)
     }
 
     #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
-        let n = self.len();
+        let n = self.0.len();
         (n, Some(n))
     }
 
     #[inline]
     fn count(self) -> usize {
-        self.len()
+        self.0.len()
     }
 
-    fn last(self) -> Option<char> {
-        match self.state {
-            EscapeUnicodeState::Done => None,
+    #[inline]
+    fn last(mut self) -> Option<char> {
+        self.0.next_back().map(char::from)
+    }
 
-            EscapeUnicodeState::RightBrace
-            | EscapeUnicodeState::Value
-            | EscapeUnicodeState::LeftBrace
-            | EscapeUnicodeState::Type
-            | EscapeUnicodeState::Backslash => Some('}'),
-        }
+    #[inline]
+    fn advance_by(&mut self, n: usize) -> Result<(), NonZeroUsize> {
+        self.0.advance_by(n)
     }
 }
 
@@ -233,16 +193,7 @@ impl Iterator for EscapeUnicode {
 impl ExactSizeIterator for EscapeUnicode {
     #[inline]
     fn len(&self) -> usize {
-        // The match is a single memory access with no branching
-        self.hex_digit_idx
-            + match self.state {
-                EscapeUnicodeState::Done => 0,
-                EscapeUnicodeState::RightBrace => 1,
-                EscapeUnicodeState::Value => 2,
-                EscapeUnicodeState::LeftBrace => 3,
-                EscapeUnicodeState::Type => 4,
-                EscapeUnicodeState::Backslash => 5,
-            }
+        self.0.len()
     }
 }
 
@@ -252,10 +203,7 @@ impl FusedIterator for EscapeUnicode {}
 #[stable(feature = "char_struct_display", since = "1.16.0")]
 impl fmt::Display for EscapeUnicode {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        for c in self.clone() {
-            f.write_char(c)?;
-        }
-        Ok(())
+        f.write_str(self.0.as_str())
     }
 }
 
@@ -267,90 +215,60 @@ impl fmt::Display for EscapeUnicode {
 /// [`escape_default`]: char::escape_default
 #[derive(Clone, Debug)]
 #[stable(feature = "rust1", since = "1.0.0")]
-pub struct EscapeDefault {
-    state: EscapeDefaultState,
-}
+pub struct EscapeDefault(escape::EscapeIterInner<10>);
 
-#[derive(Clone, Debug)]
-enum EscapeDefaultState {
-    Done,
-    Char(char),
-    Backslash(char),
-    Unicode(EscapeUnicode),
+impl EscapeDefault {
+    fn printable(chr: u8) -> Self {
+        let data = [chr, 0, 0, 0, 0, 0, 0, 0, 0, 0];
+        Self(escape::EscapeIterInner::new(data, 0..1))
+    }
+
+    fn backslash(chr: u8) -> Self {
+        let data = [b'\\', chr, 0, 0, 0, 0, 0, 0, 0, 0];
+        Self(escape::EscapeIterInner::new(data, 0..2))
+    }
+
+    fn from_unicode(esc: EscapeUnicode) -> Self {
+        Self(esc.0)
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Iterator for EscapeDefault {
     type Item = char;
 
+    #[inline]
     fn next(&mut self) -> Option<char> {
-        match self.state {
-            EscapeDefaultState::Backslash(c) => {
-                self.state = EscapeDefaultState::Char(c);
-                Some('\\')
-            }
-            EscapeDefaultState::Char(c) => {
-                self.state = EscapeDefaultState::Done;
-                Some(c)
-            }
-            EscapeDefaultState::Done => None,
-            EscapeDefaultState::Unicode(ref mut iter) => iter.next(),
-        }
+        self.0.next().map(char::from)
     }
 
     #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
-        let n = self.len();
+        let n = self.0.len();
         (n, Some(n))
     }
 
     #[inline]
     fn count(self) -> usize {
-        self.len()
+        self.0.len()
     }
 
-    fn nth(&mut self, n: usize) -> Option<char> {
-        match self.state {
-            EscapeDefaultState::Backslash(c) if n == 0 => {
-                self.state = EscapeDefaultState::Char(c);
-                Some('\\')
-            }
-            EscapeDefaultState::Backslash(c) if n == 1 => {
-                self.state = EscapeDefaultState::Done;
-                Some(c)
-            }
-            EscapeDefaultState::Backslash(_) => {
-                self.state = EscapeDefaultState::Done;
-                None
-            }
-            EscapeDefaultState::Char(c) => {
-                self.state = EscapeDefaultState::Done;
-
-                if n == 0 { Some(c) } else { None }
-            }
-            EscapeDefaultState::Done => None,
-            EscapeDefaultState::Unicode(ref mut i) => i.nth(n),
-        }
+    #[inline]
+    fn last(mut self) -> Option<char> {
+        self.0.next_back().map(char::from)
     }
 
-    fn last(self) -> Option<char> {
-        match self.state {
-            EscapeDefaultState::Unicode(iter) => iter.last(),
-            EscapeDefaultState::Done => None,
-            EscapeDefaultState::Backslash(c) | EscapeDefaultState::Char(c) => Some(c),
-        }
+    #[inline]
+    fn advance_by(&mut self, n: usize) -> Result<(), NonZeroUsize> {
+        self.0.advance_by(n)
     }
 }
 
 #[stable(feature = "exact_size_escape", since = "1.11.0")]
 impl ExactSizeIterator for EscapeDefault {
+    #[inline]
     fn len(&self) -> usize {
-        match self.state {
-            EscapeDefaultState::Done => 0,
-            EscapeDefaultState::Char(_) => 1,
-            EscapeDefaultState::Backslash(_) => 2,
-            EscapeDefaultState::Unicode(ref iter) => iter.len(),
-        }
+        self.0.len()
     }
 }
 
@@ -360,10 +278,7 @@ impl FusedIterator for EscapeDefault {}
 #[stable(feature = "char_struct_display", since = "1.16.0")]
 impl fmt::Display for EscapeDefault {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        for c in self.clone() {
-            f.write_char(c)?;
-        }
-        Ok(())
+        f.write_str(self.0.as_str())
     }
 }
 
@@ -375,21 +290,74 @@ impl fmt::Display for EscapeDefault {
 /// [`escape_debug`]: char::escape_debug
 #[stable(feature = "char_escape_debug", since = "1.20.0")]
 #[derive(Clone, Debug)]
-pub struct EscapeDebug(EscapeDefault);
+pub struct EscapeDebug(EscapeDebugInner);
+
+#[derive(Clone, Debug)]
+// Note: It’s possible to manually encode the EscapeDebugInner inside of
+// EscapeIterInner (e.g. with alive=254..255 indicating that data[0..4] holds
+// a char) which would likely result in a more optimised code.  For now we use
+// the option easier to implement.
+enum EscapeDebugInner {
+    Bytes(escape::EscapeIterInner<10>),
+    Char(char),
+}
+
+impl EscapeDebug {
+    fn printable(chr: char) -> Self {
+        Self(EscapeDebugInner::Char(chr))
+    }
+
+    fn backslash(chr: u8) -> Self {
+        let data = [b'\\', chr, 0, 0, 0, 0, 0, 0, 0, 0];
+        let iter = escape::EscapeIterInner::new(data, 0..2);
+        Self(EscapeDebugInner::Bytes(iter))
+    }
+
+    fn from_unicode(esc: EscapeUnicode) -> Self {
+        Self(EscapeDebugInner::Bytes(esc.0))
+    }
+
+    fn clear(&mut self) {
+        let bytes = escape::EscapeIterInner::new([0; 10], 0..0);
+        self.0 = EscapeDebugInner::Bytes(bytes);
+    }
+}
 
 #[stable(feature = "char_escape_debug", since = "1.20.0")]
 impl Iterator for EscapeDebug {
     type Item = char;
+
+    #[inline]
     fn next(&mut self) -> Option<char> {
-        self.0.next()
+        match self.0 {
+            EscapeDebugInner::Bytes(ref mut bytes) => bytes.next().map(char::from),
+            EscapeDebugInner::Char(chr) => {
+                self.clear();
+                Some(chr)
+            }
+        }
     }
+
     fn size_hint(&self) -> (usize, Option<usize>) {
-        self.0.size_hint()
+        let n = self.len();
+        (n, Some(n))
+    }
+
+    #[inline]
+    fn count(self) -> usize {
+        self.len()
     }
 }
 
 #[stable(feature = "char_escape_debug", since = "1.20.0")]
-impl ExactSizeIterator for EscapeDebug {}
+impl ExactSizeIterator for EscapeDebug {
+    fn len(&self) -> usize {
+        match &self.0 {
+            EscapeDebugInner::Bytes(bytes) => bytes.len(),
+            EscapeDebugInner::Char(_) => 1,
+        }
+    }
+}
 
 #[stable(feature = "fused", since = "1.26.0")]
 impl FusedIterator for EscapeDebug {}
@@ -397,7 +365,10 @@ impl FusedIterator for EscapeDebug {}
 #[stable(feature = "char_escape_debug", since = "1.20.0")]
 impl fmt::Display for EscapeDebug {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Display::fmt(&self.0, f)
+        match &self.0 {
+            EscapeDebugInner::Bytes(bytes) => f.write_str(bytes.as_str()),
+            EscapeDebugInner::Char(chr) => f.write_char(*chr),
+        }
     }
 }
 
diff --git a/library/core/src/escape.rs b/library/core/src/escape.rs
new file mode 100644
index 00000000000..20ac3cf027f
--- /dev/null
+++ b/library/core/src/escape.rs
@@ -0,0 +1,99 @@
+//! Helper code for character escaping.
+
+use crate::num::NonZeroUsize;
+use crate::ops::Range;
+
+const HEX_DIGITS: [u8; 16] = *b"0123456789abcdef";
+
+/// Escapes a byte into provided buffer; returns length of escaped
+/// representation.
+pub(crate) fn escape_ascii_into(output: &mut [u8; 4], byte: u8) -> Range<u8> {
+    let (data, len) = match byte {
+        b'\t' => ([b'\\', b't', 0, 0], 2),
+        b'\r' => ([b'\\', b'r', 0, 0], 2),
+        b'\n' => ([b'\\', b'n', 0, 0], 2),
+        b'\\' => ([b'\\', b'\\', 0, 0], 2),
+        b'\'' => ([b'\\', b'\'', 0, 0], 2),
+        b'"' => ([b'\\', b'"', 0, 0], 2),
+        b'\x20'..=b'\x7e' => ([byte, 0, 0, 0], 1),
+        _ => {
+            let hi = HEX_DIGITS[usize::from(byte >> 4)];
+            let lo = HEX_DIGITS[usize::from(byte & 0xf)];
+            ([b'\\', b'x', hi, lo], 4)
+        }
+    };
+    *output = data;
+    0..(len as u8)
+}
+
+/// Escapes a character into provided buffer using `\u{NNNN}` representation.
+pub(crate) fn escape_unicode_into(output: &mut [u8; 10], ch: char) -> Range<u8> {
+    output[9] = b'}';
+
+    let ch = ch as u32;
+    output[3] = HEX_DIGITS[((ch >> 20) & 15) as usize];
+    output[4] = HEX_DIGITS[((ch >> 16) & 15) as usize];
+    output[5] = HEX_DIGITS[((ch >> 12) & 15) as usize];
+    output[6] = HEX_DIGITS[((ch >> 8) & 15) as usize];
+    output[7] = HEX_DIGITS[((ch >> 4) & 15) as usize];
+    output[8] = HEX_DIGITS[((ch >> 0) & 15) as usize];
+
+    // or-ing 1 ensures that for ch==0 the code computes that one digit should
+    // be printed.
+    let start = (ch | 1).leading_zeros() as usize / 4 - 2;
+    output[start..start + 3].copy_from_slice(b"\\u{");
+
+    (start as u8)..10
+}
+
+/// An iterator over an fixed-size array.
+///
+/// This is essentially equivalent to array’s IntoIter except that indexes are
+/// limited to u8 to reduce size of the structure.
+#[derive(Clone, Debug)]
+pub(crate) struct EscapeIterInner<const N: usize> {
+    // Invariant: data[alive] is all ASCII.
+    pub(crate) data: [u8; N],
+
+    // Invariant: alive.start <= alive.end <= N.
+    pub(crate) alive: Range<u8>,
+}
+
+impl<const N: usize> EscapeIterInner<N> {
+    pub fn new(data: [u8; N], alive: Range<u8>) -> Self {
+        const { assert!(N < 256) };
+        debug_assert!(alive.start <= alive.end && usize::from(alive.end) <= N, "{alive:?}");
+        let this = Self { data, alive };
+        debug_assert!(this.as_bytes().is_ascii(), "Expected ASCII, got {:?}", this.as_bytes());
+        this
+    }
+
+    fn as_bytes(&self) -> &[u8] {
+        &self.data[usize::from(self.alive.start)..usize::from(self.alive.end)]
+    }
+
+    pub fn as_str(&self) -> &str {
+        // SAFETY: self.data[self.alive] is all ASCII characters.
+        unsafe { crate::str::from_utf8_unchecked(self.as_bytes()) }
+    }
+
+    pub fn len(&self) -> usize {
+        usize::from(self.alive.end - self.alive.start)
+    }
+
+    pub fn next(&mut self) -> Option<u8> {
+        self.alive.next().map(|i| self.data[usize::from(i)])
+    }
+
+    pub fn next_back(&mut self) -> Option<u8> {
+        self.alive.next_back().map(|i| self.data[usize::from(i)])
+    }
+
+    pub fn advance_by(&mut self, n: usize) -> Result<(), NonZeroUsize> {
+        self.alive.advance_by(n)
+    }
+
+    pub fn advance_back_by(&mut self, n: usize) -> Result<(), NonZeroUsize> {
+        self.alive.advance_back_by(n)
+    }
+}
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 24a9d81d037..a535a011aaf 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -162,6 +162,7 @@
 #![feature(const_waker)]
 #![feature(core_panic)]
 #![feature(duration_consts_float)]
+#![feature(internal_impls_macro)]
 #![feature(ip)]
 #![feature(is_ascii_octdigit)]
 #![feature(maybe_uninit_uninit_array)]
@@ -376,6 +377,7 @@ pub mod alloc;
 
 // note: does not need to be public
 mod bool;
+mod escape;
 mod tuple;
 mod unit;
 
diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs
index 82e4c648974..52f3d208aba 100644
--- a/library/core/src/marker.rs
+++ b/library/core/src/marker.rs
@@ -12,6 +12,60 @@ use crate::fmt::Debug;
 use crate::hash::Hash;
 use crate::hash::Hasher;
 
+/// Implements a given marker trait for multiple types at the same time.
+///
+/// The basic syntax looks like this:
+/// ```ignore private macro
+/// marker_impls! { MarkerTrait for u8, i8 }
+/// ```
+/// You can also implement `unsafe` traits
+/// ```ignore private macro
+/// marker_impls! { unsafe MarkerTrait for u8, i8 }
+/// ```
+/// Add attributes to all impls:
+/// ```ignore private macro
+/// marker_impls! {
+///     #[allow(lint)]
+///     #[unstable(feature = "marker_trait", issue = "none")]
+///     MarkerTrait for u8, i8
+/// }
+/// ```
+/// And use generics:
+/// ```ignore private macro
+/// marker_impls! {
+///     MarkerTrait for
+///         u8, i8,
+///         {T: ?Sized} *const T,
+///         {T: ?Sized} *mut T,
+///         {T: MarkerTrait} PhantomData<T>,
+///         u32,
+/// }
+/// ```
+#[unstable(feature = "internal_impls_macro", issue = "none")]
+macro marker_impls {
+    ( $(#[$($meta:tt)*])* $Trait:ident for $( $({$($bounds:tt)*})? $T:ty ),+ $(,)?) => {
+        // This inner macro is needed because... idk macros are weird.
+        // It allows repeating `meta` on all impls.
+        #[unstable(feature = "internal_impls_macro", issue = "none")]
+        macro _impl {
+            ( $$({$$($$bounds_:tt)*})? $$T_:ty ) => {
+                $(#[$($meta)*])* impl<$$($$($$bounds_)*)?> $Trait for $$T_ {}
+            }
+        }
+        $( _impl! { $({$($bounds)*})? $T } )+
+    },
+    ( $(#[$($meta:tt)*])* unsafe $Trait:ident for $( $({$($bounds:tt)*})? $T:ty ),+ $(,)?) => {
+        #[unstable(feature = "internal_impls_macro", issue = "none")]
+        macro _impl {
+            ( $$({$$($$bounds_:tt)*})? $$T_:ty ) => {
+                $(#[$($meta)*])* unsafe impl<$$($$($$bounds_)*)?> $Trait for $$T_ {}
+            }
+        }
+
+        $( _impl! { $({$($bounds)*})? $T } )+
+    },
+}
+
 /// Types that can be transferred across thread boundaries.
 ///
 /// This trait is automatically implemented when the compiler determines it's
@@ -214,6 +268,20 @@ pub trait StructuralEq {
     // Empty.
 }
 
+// FIXME: Remove special cases of these types from the compiler pattern checking code and always check `T: StructuralEq` instead
+marker_impls! {
+    #[unstable(feature = "structural_match", issue = "31434")]
+    StructuralEq for
+        usize, u8, u16, u32, u64, u128,
+        isize, i8, i16, i32, i64, i128,
+        bool,
+        char,
+        str /* Technically requires `[u8]: StructuralEq` */,
+        {T, const N: usize} [T; N],
+        {T} [T],
+        {T: ?Sized} &T,
+}
+
 /// Types whose values can be duplicated simply by copying bits.
 ///
 /// By default, variable bindings have 'move semantics.' In other
@@ -401,6 +469,30 @@ pub macro Copy($item:item) {
     /* compiler built-in */
 }
 
+// Implementations of `Copy` for primitive types.
+//
+// Implementations that cannot be described in Rust
+// are implemented in `traits::SelectionContext::copy_clone_conditions()`
+// in `rustc_trait_selection`.
+marker_impls! {
+    #[stable(feature = "rust1", since = "1.0.0")]
+    Copy for
+        usize, u8, u16, u32, u64, u128,
+        isize, i8, i16, i32, i64, i128,
+        f32, f64,
+        bool, char,
+        {T: ?Sized} *const T,
+        {T: ?Sized} *mut T,
+
+}
+
+#[unstable(feature = "never_type", issue = "35121")]
+impl Copy for ! {}
+
+/// Shared references can be copied, but mutable references *cannot*!
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: ?Sized> Copy for &T {}
+
 /// Types for which it is safe to share references between threads.
 ///
 /// This trait is automatically implemented when the compiler determines
@@ -778,11 +870,14 @@ pub trait DiscriminantKind {
 pub(crate) unsafe auto trait Freeze {}
 
 impl<T: ?Sized> !Freeze for UnsafeCell<T> {}
-unsafe impl<T: ?Sized> Freeze for PhantomData<T> {}
-unsafe impl<T: ?Sized> Freeze for *const T {}
-unsafe impl<T: ?Sized> Freeze for *mut T {}
-unsafe impl<T: ?Sized> Freeze for &T {}
-unsafe impl<T: ?Sized> Freeze for &mut T {}
+marker_impls! {
+    unsafe Freeze for
+        {T: ?Sized} PhantomData<T>,
+        {T: ?Sized} *const T,
+        {T: ?Sized} *mut T,
+        {T: ?Sized} &T,
+        {T: ?Sized} &mut T,
+}
 
 /// Types that can be safely moved after being pinned.
 ///
@@ -843,17 +938,19 @@ pub struct PhantomPinned;
 #[stable(feature = "pin", since = "1.33.0")]
 impl !Unpin for PhantomPinned {}
 
-#[stable(feature = "pin", since = "1.33.0")]
-impl<'a, T: ?Sized + 'a> Unpin for &'a T {}
-
-#[stable(feature = "pin", since = "1.33.0")]
-impl<'a, T: ?Sized + 'a> Unpin for &'a mut T {}
-
-#[stable(feature = "pin_raw", since = "1.38.0")]
-impl<T: ?Sized> Unpin for *const T {}
+marker_impls! {
+    #[stable(feature = "pin", since = "1.33.0")]
+    Unpin for
+        {T: ?Sized} &T,
+        {T: ?Sized} &mut T,
+}
 
-#[stable(feature = "pin_raw", since = "1.38.0")]
-impl<T: ?Sized> Unpin for *mut T {}
+marker_impls! {
+    #[stable(feature = "pin_raw", since = "1.38.0")]
+    Unpin for
+        {T: ?Sized} *const T,
+        {T: ?Sized} *mut T,
+}
 
 /// A marker for types that can be dropped.
 ///
@@ -888,43 +985,25 @@ pub trait Tuple {}
 )]
 pub trait PointerLike {}
 
-/// Implementations of `Copy` for primitive types.
-///
-/// Implementations that cannot be described in Rust
-/// are implemented in `traits::SelectionContext::copy_clone_conditions()`
-/// in `rustc_trait_selection`.
-mod copy_impls {
-
-    use super::Copy;
-
-    macro_rules! impl_copy {
-        ($($t:ty)*) => {
-            $(
-                #[stable(feature = "rust1", since = "1.0.0")]
-                impl Copy for $t {}
-            )*
-        }
-    }
-
-    impl_copy! {
-        usize u8 u16 u32 u64 u128
-        isize i8 i16 i32 i64 i128
-        f32 f64
-        bool char
-    }
-
-    #[unstable(feature = "never_type", issue = "35121")]
-    impl Copy for ! {}
-
-    #[stable(feature = "rust1", since = "1.0.0")]
-    impl<T: ?Sized> Copy for *const T {}
-
-    #[stable(feature = "rust1", since = "1.0.0")]
-    impl<T: ?Sized> Copy for *mut T {}
-
-    /// Shared references can be copied, but mutable references *cannot*!
-    #[stable(feature = "rust1", since = "1.0.0")]
-    impl<T: ?Sized> Copy for &T {}
+/// A marker for types which can be used as types of `const` generic parameters.
+#[cfg_attr(not(bootstrap), lang = "const_param_ty")]
+#[unstable(feature = "adt_const_params", issue = "95174")]
+#[rustc_on_unimplemented(message = "`{Self}` can't be used as a const parameter type")]
+pub trait ConstParamTy: StructuralEq {}
+
+// FIXME(generic_const_parameter_types): handle `ty::FnDef`/`ty::Closure`
+// FIXME(generic_const_parameter_types): handle `ty::Tuple`
+marker_impls! {
+    #[unstable(feature = "adt_const_params", issue = "95174")]
+    ConstParamTy for
+        usize, u8, u16, u32, u64, u128,
+        isize, i8, i16, i32, i64, i128,
+        bool,
+        char,
+        str /* Technically requires `[u8]: ConstParamTy` */,
+        {T: ConstParamTy, const N: usize} [T; N],
+        {T: ConstParamTy} [T],
+        {T: ?Sized + ConstParamTy} &T,
 }
 
 /// A common trait implemented by all function pointers.
diff --git a/library/core/tests/clone.rs b/library/core/tests/clone.rs
index 33ca9f2c6a3..aafe5ced2e9 100644
--- a/library/core/tests/clone.rs
+++ b/library/core/tests/clone.rs
@@ -1,4 +1,5 @@
 #[test]
+#[cfg_attr(not(bootstrap), allow(suspicious_double_ref_op))]
 fn test_borrowed_clone() {
     let x = 5;
     let y: &i32 = &x;
diff --git a/library/std/src/sys/common/thread_local/mod.rs b/library/std/src/sys/common/thread_local/mod.rs
index a7528c06c9d..951d509ec95 100644
--- a/library/std/src/sys/common/thread_local/mod.rs
+++ b/library/std/src/sys/common/thread_local/mod.rs
@@ -6,7 +6,7 @@ cfg_if::cfg_if! {
         mod static_local;
         #[doc(hidden)]
         pub use static_local::{Key, thread_local_inner};
-    } else if #[cfg(all(target_thread_local))] {
+    } else if #[cfg(target_thread_local)] {
         #[doc(hidden)]
         mod fast_local;
         #[doc(hidden)]
diff --git a/src/doc/unstable-book/src/language-features/debugger-visualizer.md b/src/doc/unstable-book/src/language-features/debugger-visualizer.md
deleted file mode 100644
index c7a0414b676..00000000000
--- a/src/doc/unstable-book/src/language-features/debugger-visualizer.md
+++ /dev/null
@@ -1,27 +0,0 @@
-# `debugger_visualizer`
-
-The tracking issue for this feature is: [#95939]
-
-[#95939]: https://github.com/rust-lang/rust/issues/95939
-
-------------------------
-
-The `debugger_visualizer` attribute can be used to instruct the compiler
-to embed a debugger visualizer file into the PDB/ELF generated by `rustc`.
-
-## Examples
-
-``` rust,ignore (partial-example)
-#![feature(debugger_visualizer)]
-#![debugger_visualizer(natvis_file = "foo.natvis")]
-#![debugger_visualizer(gdb_script_file = "foo.py")]
-struct Foo {
-
-}
-```
-
-## Limitations
-
-Currently, this feature only supports embedding Natvis files on `-windows-msvc`
-targets via the `natvis_file` meta item. `-windows-gnu` targets are not currently
-supported.
diff --git a/src/librustdoc/html/format.rs b/src/librustdoc/html/format.rs
index 1b445b8981e..297120da284 100644
--- a/src/librustdoc/html/format.rs
+++ b/src/librustdoc/html/format.rs
@@ -167,7 +167,7 @@ pub(crate) fn print_generic_bounds<'a, 'tcx: 'a>(
     display_fn(move |f| {
         let mut bounds_dup = FxHashSet::default();
 
-        for (i, bound) in bounds.iter().filter(|b| bounds_dup.insert(b.clone())).enumerate() {
+        for (i, bound) in bounds.iter().filter(|b| bounds_dup.insert(*b)).enumerate() {
             if i > 0 {
                 f.write_str(" + ")?;
             }
diff --git a/src/tools/clippy/clippy_lints/src/declared_lints.rs b/src/tools/clippy/clippy_lints/src/declared_lints.rs
index 0c66d36a1d6..fa726a64937 100644
--- a/src/tools/clippy/clippy_lints/src/declared_lints.rs
+++ b/src/tools/clippy/clippy_lints/src/declared_lints.rs
@@ -313,7 +313,6 @@ pub(crate) static LINTS: &[&crate::LintInfo] = &[
     crate::methods::CHARS_NEXT_CMP_INFO,
     crate::methods::CLEAR_WITH_DRAIN_INFO,
     crate::methods::CLONED_INSTEAD_OF_COPIED_INFO,
-    crate::methods::CLONE_DOUBLE_REF_INFO,
     crate::methods::CLONE_ON_COPY_INFO,
     crate::methods::CLONE_ON_REF_PTR_INFO,
     crate::methods::COLLAPSIBLE_STR_REPLACE_INFO,
diff --git a/src/tools/clippy/clippy_lints/src/methods/clone_on_copy.rs b/src/tools/clippy/clippy_lints/src/methods/clone_on_copy.rs
index 3795c0ec250..65fd50dff58 100644
--- a/src/tools/clippy/clippy_lints/src/methods/clone_on_copy.rs
+++ b/src/tools/clippy/clippy_lints/src/methods/clone_on_copy.rs
@@ -1,7 +1,6 @@
-use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
+use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::get_parent_node;
 use clippy_utils::source::snippet_with_context;
-use clippy_utils::sugg;
 use clippy_utils::ty::is_copy;
 use rustc_errors::Applicability;
 use rustc_hir::{BindingAnnotation, ByRef, Expr, ExprKind, MatchSource, Node, PatKind, QPath};
@@ -9,7 +8,6 @@ use rustc_lint::LateContext;
 use rustc_middle::ty::{self, adjustment::Adjust, print::with_forced_trimmed_paths};
 use rustc_span::symbol::{sym, Symbol};
 
-use super::CLONE_DOUBLE_REF;
 use super::CLONE_ON_COPY;
 
 /// Checks for the `CLONE_ON_COPY` lint.
@@ -42,41 +40,7 @@ pub(super) fn check(
 
     let ty = cx.typeck_results().expr_ty(expr);
     if let ty::Ref(_, inner, _) = arg_ty.kind() {
-        if let ty::Ref(_, innermost, _) = inner.kind() {
-            span_lint_and_then(
-                cx,
-                CLONE_DOUBLE_REF,
-                expr.span,
-                &with_forced_trimmed_paths!(format!(
-                    "using `clone` on a double-reference; \
-                    this will copy the reference of type `{ty}` instead of cloning the inner type"
-                )),
-                |diag| {
-                    if let Some(snip) = sugg::Sugg::hir_opt(cx, arg) {
-                        let mut ty = innermost;
-                        let mut n = 0;
-                        while let ty::Ref(_, inner, _) = ty.kind() {
-                            ty = inner;
-                            n += 1;
-                        }
-                        let refs = "&".repeat(n + 1);
-                        let derefs = "*".repeat(n);
-                        let explicit = with_forced_trimmed_paths!(format!("<{refs}{ty}>::clone({snip})"));
-                        diag.span_suggestion(
-                            expr.span,
-                            "try dereferencing it",
-                            with_forced_trimmed_paths!(format!("{refs}({derefs}{}).clone()", snip.deref())),
-                            Applicability::MaybeIncorrect,
-                        );
-                        diag.span_suggestion(
-                            expr.span,
-                            "or try being explicit if you are sure, that you want to clone a reference",
-                            explicit,
-                            Applicability::MaybeIncorrect,
-                        );
-                    }
-                },
-            );
+        if let ty::Ref(..) = inner.kind() {
             return; // don't report clone_on_copy
         }
     }
diff --git a/src/tools/clippy/clippy_lints/src/methods/mod.rs b/src/tools/clippy/clippy_lints/src/methods/mod.rs
index 9cafbc2e5f5..e4a659d3ce7 100644
--- a/src/tools/clippy/clippy_lints/src/methods/mod.rs
+++ b/src/tools/clippy/clippy_lints/src/methods/mod.rs
@@ -986,29 +986,6 @@ declare_clippy_lint! {
 
 declare_clippy_lint! {
     /// ### What it does
-    /// Checks for usage of `.clone()` on an `&&T`.
-    ///
-    /// ### Why is this bad?
-    /// Cloning an `&&T` copies the inner `&T`, instead of
-    /// cloning the underlying `T`.
-    ///
-    /// ### Example
-    /// ```rust
-    /// fn main() {
-    ///     let x = vec![1];
-    ///     let y = &&x;
-    ///     let z = y.clone();
-    ///     println!("{:p} {:p}", *y, z); // prints out the same pointer
-    /// }
-    /// ```
-    #[clippy::version = "pre 1.29.0"]
-    pub CLONE_DOUBLE_REF,
-    correctness,
-    "using `clone` on `&&T`"
-}
-
-declare_clippy_lint! {
-    /// ### What it does
     /// Checks for usage of `.to_string()` on an `&&T` where
     /// `T` implements `ToString` directly (like `&&str` or `&&String`).
     ///
@@ -3258,7 +3235,6 @@ impl_lint_pass!(Methods => [
     CHARS_LAST_CMP,
     CLONE_ON_COPY,
     CLONE_ON_REF_PTR,
-    CLONE_DOUBLE_REF,
     COLLAPSIBLE_STR_REPLACE,
     ITER_OVEREAGER_CLONED,
     CLONED_INSTEAD_OF_COPIED,
diff --git a/src/tools/clippy/clippy_lints/src/renamed_lints.rs b/src/tools/clippy/clippy_lints/src/renamed_lints.rs
index 9f487dedb8c..5e81a01a461 100644
--- a/src/tools/clippy/clippy_lints/src/renamed_lints.rs
+++ b/src/tools/clippy/clippy_lints/src/renamed_lints.rs
@@ -30,6 +30,7 @@ pub static RENAMED_LINTS: &[(&str, &str)] = &[
     ("clippy::stutter", "clippy::module_name_repetitions"),
     ("clippy::to_string_in_display", "clippy::recursive_format_impl"),
     ("clippy::zero_width_space", "clippy::invisible_characters"),
+    ("clippy::clone_double_ref", "suspicious_double_ref_op"),
     ("clippy::drop_bounds", "drop_bounds"),
     ("clippy::for_loop_over_option", "for_loops_over_fallibles"),
     ("clippy::for_loop_over_result", "for_loops_over_fallibles"),
diff --git a/src/tools/clippy/tests/ui/explicit_deref_methods.fixed b/src/tools/clippy/tests/ui/explicit_deref_methods.fixed
index 77e9f5fc1fd..60482c66da7 100644
--- a/src/tools/clippy/tests/ui/explicit_deref_methods.fixed
+++ b/src/tools/clippy/tests/ui/explicit_deref_methods.fixed
@@ -3,7 +3,7 @@
 #![allow(unused_variables)]
 #![allow(
     clippy::borrow_deref_ref,
-    clippy::clone_double_ref,
+    suspicious_double_ref_op,
     clippy::explicit_auto_deref,
     clippy::needless_borrow,
     clippy::uninlined_format_args
diff --git a/src/tools/clippy/tests/ui/explicit_deref_methods.rs b/src/tools/clippy/tests/ui/explicit_deref_methods.rs
index 0c2cc7c2c3a..e3613e216bb 100644
--- a/src/tools/clippy/tests/ui/explicit_deref_methods.rs
+++ b/src/tools/clippy/tests/ui/explicit_deref_methods.rs
@@ -3,7 +3,7 @@
 #![allow(unused_variables)]
 #![allow(
     clippy::borrow_deref_ref,
-    clippy::clone_double_ref,
+    suspicious_double_ref_op,
     clippy::explicit_auto_deref,
     clippy::needless_borrow,
     clippy::uninlined_format_args
diff --git a/src/tools/clippy/tests/ui/rename.fixed b/src/tools/clippy/tests/ui/rename.fixed
index e8a00a9e7f7..ff19a042825 100644
--- a/src/tools/clippy/tests/ui/rename.fixed
+++ b/src/tools/clippy/tests/ui/rename.fixed
@@ -36,6 +36,7 @@
 #![allow(enum_intrinsics_non_enums)]
 #![allow(non_fmt_panics)]
 #![allow(named_arguments_used_positionally)]
+#![allow(suspicious_double_ref_op)]
 #![allow(temporary_cstring_as_ptr)]
 #![allow(unknown_lints)]
 #![allow(unused_labels)]
@@ -67,6 +68,7 @@
 #![warn(clippy::module_name_repetitions)]
 #![warn(clippy::recursive_format_impl)]
 #![warn(clippy::invisible_characters)]
+#![warn(suspicious_double_ref_op)]
 #![warn(drop_bounds)]
 #![warn(for_loops_over_fallibles)]
 #![warn(for_loops_over_fallibles)]
diff --git a/src/tools/clippy/tests/ui/rename.rs b/src/tools/clippy/tests/ui/rename.rs
index c8ea70c2bcb..38b1647c0cc 100644
--- a/src/tools/clippy/tests/ui/rename.rs
+++ b/src/tools/clippy/tests/ui/rename.rs
@@ -36,6 +36,7 @@
 #![allow(enum_intrinsics_non_enums)]
 #![allow(non_fmt_panics)]
 #![allow(named_arguments_used_positionally)]
+#![allow(suspicious_double_ref_op)]
 #![allow(temporary_cstring_as_ptr)]
 #![allow(unknown_lints)]
 #![allow(unused_labels)]
@@ -67,6 +68,7 @@
 #![warn(clippy::stutter)]
 #![warn(clippy::to_string_in_display)]
 #![warn(clippy::zero_width_space)]
+#![warn(clippy::clone_double_ref)]
 #![warn(clippy::drop_bounds)]
 #![warn(clippy::for_loop_over_option)]
 #![warn(clippy::for_loop_over_result)]
diff --git a/src/tools/clippy/tests/ui/rename.stderr b/src/tools/clippy/tests/ui/rename.stderr
index 27a0263292e..70d15408b9f 100644
--- a/src/tools/clippy/tests/ui/rename.stderr
+++ b/src/tools/clippy/tests/ui/rename.stderr
@@ -1,5 +1,5 @@
 error: lint `clippy::almost_complete_letter_range` has been renamed to `clippy::almost_complete_range`
-  --> $DIR/rename.rs:42:9
+  --> $DIR/rename.rs:43:9
    |
 LL | #![warn(clippy::almost_complete_letter_range)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::almost_complete_range`
@@ -7,250 +7,256 @@ LL | #![warn(clippy::almost_complete_letter_range)]
    = note: `-D renamed-and-removed-lints` implied by `-D warnings`
 
 error: lint `clippy::blacklisted_name` has been renamed to `clippy::disallowed_names`
-  --> $DIR/rename.rs:43:9
+  --> $DIR/rename.rs:44:9
    |
 LL | #![warn(clippy::blacklisted_name)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::disallowed_names`
 
 error: lint `clippy::block_in_if_condition_expr` has been renamed to `clippy::blocks_in_if_conditions`
-  --> $DIR/rename.rs:44:9
+  --> $DIR/rename.rs:45:9
    |
 LL | #![warn(clippy::block_in_if_condition_expr)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::blocks_in_if_conditions`
 
 error: lint `clippy::block_in_if_condition_stmt` has been renamed to `clippy::blocks_in_if_conditions`
-  --> $DIR/rename.rs:45:9
+  --> $DIR/rename.rs:46:9
    |
 LL | #![warn(clippy::block_in_if_condition_stmt)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::blocks_in_if_conditions`
 
 error: lint `clippy::box_vec` has been renamed to `clippy::box_collection`
-  --> $DIR/rename.rs:46:9
+  --> $DIR/rename.rs:47:9
    |
 LL | #![warn(clippy::box_vec)]
    |         ^^^^^^^^^^^^^^^ help: use the new name: `clippy::box_collection`
 
 error: lint `clippy::const_static_lifetime` has been renamed to `clippy::redundant_static_lifetimes`
-  --> $DIR/rename.rs:47:9
+  --> $DIR/rename.rs:48:9
    |
 LL | #![warn(clippy::const_static_lifetime)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::redundant_static_lifetimes`
 
 error: lint `clippy::cyclomatic_complexity` has been renamed to `clippy::cognitive_complexity`
-  --> $DIR/rename.rs:48:9
+  --> $DIR/rename.rs:49:9
    |
 LL | #![warn(clippy::cyclomatic_complexity)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::cognitive_complexity`
 
 error: lint `clippy::derive_hash_xor_eq` has been renamed to `clippy::derived_hash_with_manual_eq`
-  --> $DIR/rename.rs:49:9
+  --> $DIR/rename.rs:50:9
    |
 LL | #![warn(clippy::derive_hash_xor_eq)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::derived_hash_with_manual_eq`
 
 error: lint `clippy::disallowed_method` has been renamed to `clippy::disallowed_methods`
-  --> $DIR/rename.rs:50:9
+  --> $DIR/rename.rs:51:9
    |
 LL | #![warn(clippy::disallowed_method)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::disallowed_methods`
 
 error: lint `clippy::disallowed_type` has been renamed to `clippy::disallowed_types`
-  --> $DIR/rename.rs:51:9
+  --> $DIR/rename.rs:52:9
    |
 LL | #![warn(clippy::disallowed_type)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::disallowed_types`
 
 error: lint `clippy::eval_order_dependence` has been renamed to `clippy::mixed_read_write_in_expression`
-  --> $DIR/rename.rs:52:9
+  --> $DIR/rename.rs:53:9
    |
 LL | #![warn(clippy::eval_order_dependence)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::mixed_read_write_in_expression`
 
 error: lint `clippy::identity_conversion` has been renamed to `clippy::useless_conversion`
-  --> $DIR/rename.rs:53:9
+  --> $DIR/rename.rs:54:9
    |
 LL | #![warn(clippy::identity_conversion)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::useless_conversion`
 
 error: lint `clippy::if_let_some_result` has been renamed to `clippy::match_result_ok`
-  --> $DIR/rename.rs:54:9
+  --> $DIR/rename.rs:55:9
    |
 LL | #![warn(clippy::if_let_some_result)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::match_result_ok`
 
 error: lint `clippy::logic_bug` has been renamed to `clippy::overly_complex_bool_expr`
-  --> $DIR/rename.rs:55:9
+  --> $DIR/rename.rs:56:9
    |
 LL | #![warn(clippy::logic_bug)]
    |         ^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::overly_complex_bool_expr`
 
 error: lint `clippy::new_without_default_derive` has been renamed to `clippy::new_without_default`
-  --> $DIR/rename.rs:56:9
+  --> $DIR/rename.rs:57:9
    |
 LL | #![warn(clippy::new_without_default_derive)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::new_without_default`
 
 error: lint `clippy::option_and_then_some` has been renamed to `clippy::bind_instead_of_map`
-  --> $DIR/rename.rs:57:9
+  --> $DIR/rename.rs:58:9
    |
 LL | #![warn(clippy::option_and_then_some)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::bind_instead_of_map`
 
 error: lint `clippy::option_expect_used` has been renamed to `clippy::expect_used`
-  --> $DIR/rename.rs:58:9
+  --> $DIR/rename.rs:59:9
    |
 LL | #![warn(clippy::option_expect_used)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::expect_used`
 
 error: lint `clippy::option_map_unwrap_or` has been renamed to `clippy::map_unwrap_or`
-  --> $DIR/rename.rs:59:9
+  --> $DIR/rename.rs:60:9
    |
 LL | #![warn(clippy::option_map_unwrap_or)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::map_unwrap_or`
 
 error: lint `clippy::option_map_unwrap_or_else` has been renamed to `clippy::map_unwrap_or`
-  --> $DIR/rename.rs:60:9
+  --> $DIR/rename.rs:61:9
    |
 LL | #![warn(clippy::option_map_unwrap_or_else)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::map_unwrap_or`
 
 error: lint `clippy::option_unwrap_used` has been renamed to `clippy::unwrap_used`
-  --> $DIR/rename.rs:61:9
+  --> $DIR/rename.rs:62:9
    |
 LL | #![warn(clippy::option_unwrap_used)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::unwrap_used`
 
 error: lint `clippy::ref_in_deref` has been renamed to `clippy::needless_borrow`
-  --> $DIR/rename.rs:62:9
+  --> $DIR/rename.rs:63:9
    |
 LL | #![warn(clippy::ref_in_deref)]
    |         ^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::needless_borrow`
 
 error: lint `clippy::result_expect_used` has been renamed to `clippy::expect_used`
-  --> $DIR/rename.rs:63:9
+  --> $DIR/rename.rs:64:9
    |
 LL | #![warn(clippy::result_expect_used)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::expect_used`
 
 error: lint `clippy::result_map_unwrap_or_else` has been renamed to `clippy::map_unwrap_or`
-  --> $DIR/rename.rs:64:9
+  --> $DIR/rename.rs:65:9
    |
 LL | #![warn(clippy::result_map_unwrap_or_else)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::map_unwrap_or`
 
 error: lint `clippy::result_unwrap_used` has been renamed to `clippy::unwrap_used`
-  --> $DIR/rename.rs:65:9
+  --> $DIR/rename.rs:66:9
    |
 LL | #![warn(clippy::result_unwrap_used)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::unwrap_used`
 
 error: lint `clippy::single_char_push_str` has been renamed to `clippy::single_char_add_str`
-  --> $DIR/rename.rs:66:9
+  --> $DIR/rename.rs:67:9
    |
 LL | #![warn(clippy::single_char_push_str)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::single_char_add_str`
 
 error: lint `clippy::stutter` has been renamed to `clippy::module_name_repetitions`
-  --> $DIR/rename.rs:67:9
+  --> $DIR/rename.rs:68:9
    |
 LL | #![warn(clippy::stutter)]
    |         ^^^^^^^^^^^^^^^ help: use the new name: `clippy::module_name_repetitions`
 
 error: lint `clippy::to_string_in_display` has been renamed to `clippy::recursive_format_impl`
-  --> $DIR/rename.rs:68:9
+  --> $DIR/rename.rs:69:9
    |
 LL | #![warn(clippy::to_string_in_display)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::recursive_format_impl`
 
 error: lint `clippy::zero_width_space` has been renamed to `clippy::invisible_characters`
-  --> $DIR/rename.rs:69:9
+  --> $DIR/rename.rs:70:9
    |
 LL | #![warn(clippy::zero_width_space)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::invisible_characters`
 
+error: lint `clippy::clone_double_ref` has been renamed to `suspicious_double_ref_op`
+  --> $DIR/rename.rs:71:9
+   |
+LL | #![warn(clippy::clone_double_ref)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `suspicious_double_ref_op`
+
 error: lint `clippy::drop_bounds` has been renamed to `drop_bounds`
-  --> $DIR/rename.rs:70:9
+  --> $DIR/rename.rs:72:9
    |
 LL | #![warn(clippy::drop_bounds)]
    |         ^^^^^^^^^^^^^^^^^^^ help: use the new name: `drop_bounds`
 
 error: lint `clippy::for_loop_over_option` has been renamed to `for_loops_over_fallibles`
-  --> $DIR/rename.rs:71:9
+  --> $DIR/rename.rs:73:9
    |
 LL | #![warn(clippy::for_loop_over_option)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `for_loops_over_fallibles`
 
 error: lint `clippy::for_loop_over_result` has been renamed to `for_loops_over_fallibles`
-  --> $DIR/rename.rs:72:9
+  --> $DIR/rename.rs:74:9
    |
 LL | #![warn(clippy::for_loop_over_result)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `for_loops_over_fallibles`
 
 error: lint `clippy::for_loops_over_fallibles` has been renamed to `for_loops_over_fallibles`
-  --> $DIR/rename.rs:73:9
+  --> $DIR/rename.rs:75:9
    |
 LL | #![warn(clippy::for_loops_over_fallibles)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `for_loops_over_fallibles`
 
 error: lint `clippy::into_iter_on_array` has been renamed to `array_into_iter`
-  --> $DIR/rename.rs:74:9
+  --> $DIR/rename.rs:76:9
    |
 LL | #![warn(clippy::into_iter_on_array)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `array_into_iter`
 
 error: lint `clippy::invalid_atomic_ordering` has been renamed to `invalid_atomic_ordering`
-  --> $DIR/rename.rs:75:9
+  --> $DIR/rename.rs:77:9
    |
 LL | #![warn(clippy::invalid_atomic_ordering)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `invalid_atomic_ordering`
 
 error: lint `clippy::invalid_ref` has been renamed to `invalid_value`
-  --> $DIR/rename.rs:76:9
+  --> $DIR/rename.rs:78:9
    |
 LL | #![warn(clippy::invalid_ref)]
    |         ^^^^^^^^^^^^^^^^^^^ help: use the new name: `invalid_value`
 
 error: lint `clippy::let_underscore_drop` has been renamed to `let_underscore_drop`
-  --> $DIR/rename.rs:77:9
+  --> $DIR/rename.rs:79:9
    |
 LL | #![warn(clippy::let_underscore_drop)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `let_underscore_drop`
 
 error: lint `clippy::mem_discriminant_non_enum` has been renamed to `enum_intrinsics_non_enums`
-  --> $DIR/rename.rs:78:9
+  --> $DIR/rename.rs:80:9
    |
 LL | #![warn(clippy::mem_discriminant_non_enum)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `enum_intrinsics_non_enums`
 
 error: lint `clippy::panic_params` has been renamed to `non_fmt_panics`
-  --> $DIR/rename.rs:79:9
+  --> $DIR/rename.rs:81:9
    |
 LL | #![warn(clippy::panic_params)]
    |         ^^^^^^^^^^^^^^^^^^^^ help: use the new name: `non_fmt_panics`
 
 error: lint `clippy::positional_named_format_parameters` has been renamed to `named_arguments_used_positionally`
-  --> $DIR/rename.rs:80:9
+  --> $DIR/rename.rs:82:9
    |
 LL | #![warn(clippy::positional_named_format_parameters)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `named_arguments_used_positionally`
 
 error: lint `clippy::temporary_cstring_as_ptr` has been renamed to `temporary_cstring_as_ptr`
-  --> $DIR/rename.rs:81:9
+  --> $DIR/rename.rs:83:9
    |
 LL | #![warn(clippy::temporary_cstring_as_ptr)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `temporary_cstring_as_ptr`
 
 error: lint `clippy::unknown_clippy_lints` has been renamed to `unknown_lints`
-  --> $DIR/rename.rs:82:9
+  --> $DIR/rename.rs:84:9
    |
 LL | #![warn(clippy::unknown_clippy_lints)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `unknown_lints`
 
 error: lint `clippy::unused_label` has been renamed to `unused_labels`
-  --> $DIR/rename.rs:83:9
+  --> $DIR/rename.rs:85:9
    |
 LL | #![warn(clippy::unused_label)]
    |         ^^^^^^^^^^^^^^^^^^^^ help: use the new name: `unused_labels`
 
-error: aborting due to 42 previous errors
+error: aborting due to 43 previous errors
 
diff --git a/src/tools/clippy/tests/ui/unnecessary_clone.rs b/src/tools/clippy/tests/ui/unnecessary_clone.rs
index 8b1629b19a7..7ceed3c75fd 100644
--- a/src/tools/clippy/tests/ui/unnecessary_clone.rs
+++ b/src/tools/clippy/tests/ui/unnecessary_clone.rs
@@ -42,14 +42,6 @@ fn clone_on_copy_generic<T: Copy>(t: T) {
     Some(t).clone();
 }
 
-fn clone_on_double_ref() {
-    let x = vec![1];
-    let y = &&x;
-    let z: &Vec<_> = y.clone();
-
-    println!("{:p} {:p}", *y, z);
-}
-
 mod many_derefs {
     struct A;
     struct B;
@@ -84,11 +76,6 @@ mod many_derefs {
         let _: E = a.clone();
         let _: E = *****a;
     }
-
-    fn check(mut encoded: &[u8]) {
-        let _ = &mut encoded.clone();
-        let _ = &encoded.clone();
-    }
 }
 
 mod issue2076 {
diff --git a/src/tools/clippy/tests/ui/unnecessary_clone.stderr b/src/tools/clippy/tests/ui/unnecessary_clone.stderr
index 6022d9fa4c5..5686ab6b453 100644
--- a/src/tools/clippy/tests/ui/unnecessary_clone.stderr
+++ b/src/tools/clippy/tests/ui/unnecessary_clone.stderr
@@ -44,63 +44,17 @@ error: using `clone` on type `Option<T>` which implements the `Copy` trait
 LL |     Some(t).clone();
    |     ^^^^^^^^^^^^^^^ help: try removing the `clone` call: `Some(t)`
 
-error: using `clone` on a double-reference; this will copy the reference of type `&Vec<i32>` instead of cloning the inner type
-  --> $DIR/unnecessary_clone.rs:48:22
-   |
-LL |     let z: &Vec<_> = y.clone();
-   |                      ^^^^^^^^^
-   |
-   = note: `#[deny(clippy::clone_double_ref)]` on by default
-help: try dereferencing it
-   |
-LL |     let z: &Vec<_> = &(*y).clone();
-   |                      ~~~~~~~~~~~~~
-help: or try being explicit if you are sure, that you want to clone a reference
-   |
-LL |     let z: &Vec<_> = <&Vec<i32>>::clone(y);
-   |                      ~~~~~~~~~~~~~~~~~~~~~
-
 error: using `clone` on type `E` which implements the `Copy` trait
-  --> $DIR/unnecessary_clone.rs:84:20
+  --> $DIR/unnecessary_clone.rs:76:20
    |
 LL |         let _: E = a.clone();
    |                    ^^^^^^^^^ help: try dereferencing it: `*****a`
 
-error: using `clone` on a double-reference; this will copy the reference of type `&[u8]` instead of cloning the inner type
-  --> $DIR/unnecessary_clone.rs:89:22
-   |
-LL |         let _ = &mut encoded.clone();
-   |                      ^^^^^^^^^^^^^^^
-   |
-help: try dereferencing it
-   |
-LL |         let _ = &mut &(*encoded).clone();
-   |                      ~~~~~~~~~~~~~~~~~~~
-help: or try being explicit if you are sure, that you want to clone a reference
-   |
-LL |         let _ = &mut <&[u8]>::clone(encoded);
-   |                      ~~~~~~~~~~~~~~~~~~~~~~~
-
-error: using `clone` on a double-reference; this will copy the reference of type `&[u8]` instead of cloning the inner type
-  --> $DIR/unnecessary_clone.rs:90:18
-   |
-LL |         let _ = &encoded.clone();
-   |                  ^^^^^^^^^^^^^^^
-   |
-help: try dereferencing it
-   |
-LL |         let _ = &&(*encoded).clone();
-   |                  ~~~~~~~~~~~~~~~~~~~
-help: or try being explicit if you are sure, that you want to clone a reference
-   |
-LL |         let _ = &<&[u8]>::clone(encoded);
-   |                  ~~~~~~~~~~~~~~~~~~~~~~~
-
 error: using `.clone()` on a ref-counted pointer
-  --> $DIR/unnecessary_clone.rs:108:14
+  --> $DIR/unnecessary_clone.rs:95:14
    |
 LL |         Some(try_opt!(Some(rc)).clone())
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `Rc::<u8>::clone(&try_opt!(Some(rc)))`
 
-error: aborting due to 12 previous errors
+error: aborting due to 9 previous errors
 
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index 0fd9f3ae3f4..a4be7af886b 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -1385,7 +1385,9 @@ impl<'test> TestCx<'test> {
         let actual_errors = json::parse_output(&diagnostic_file_name, &proc_res.stderr, proc_res);
         let mut unexpected = Vec::new();
         let mut found = vec![false; expected_errors.len()];
-        for actual_error in &actual_errors {
+        for mut actual_error in actual_errors {
+            actual_error.msg = self.normalize_output(&actual_error.msg, &[]);
+
             let opt_index =
                 expected_errors.iter().enumerate().position(|(index, expected_error)| {
                     !found[index]
@@ -1404,7 +1406,8 @@ impl<'test> TestCx<'test> {
 
                 None => {
                     // If the test is a known bug, don't require that the error is annotated
-                    if self.is_unexpected_compiler_message(actual_error, expect_help, expect_note) {
+                    if self.is_unexpected_compiler_message(&actual_error, expect_help, expect_note)
+                    {
                         self.error(&format!(
                             "{}:{}: unexpected {}: '{}'",
                             file_name,
diff --git a/tests/debuginfo/auxiliary/dependency-with-embedded-visualizers.rs b/tests/debuginfo/auxiliary/dependency-with-embedded-visualizers.rs
index 327515b10af..c187df637fd 100644
--- a/tests/debuginfo/auxiliary/dependency-with-embedded-visualizers.rs
+++ b/tests/debuginfo/auxiliary/dependency-with-embedded-visualizers.rs
@@ -2,7 +2,6 @@
 // ignore-lldb
 // no-prefer-dynamic
 
-#![feature(debugger_visualizer)]
 #![debugger_visualizer(natvis_file = "dependency-with-embedded-visualizers.natvis")]
 #![debugger_visualizer(gdb_script_file = "dependency-with-embedded-visualizers.py")]
 #![crate_type = "rlib"]
diff --git a/tests/debuginfo/embedded-visualizer.rs b/tests/debuginfo/embedded-visualizer.rs
index 2898e75e0ee..ac421092839 100644
--- a/tests/debuginfo/embedded-visualizer.rs
+++ b/tests/debuginfo/embedded-visualizer.rs
@@ -60,7 +60,6 @@
 // gdb-check:$4 = "Person A" is 10 years old.
 
 #![allow(unused_variables)]
-#![feature(debugger_visualizer)]
 #![debugger_visualizer(natvis_file = "embedded-visualizer.natvis")]
 #![debugger_visualizer(gdb_script_file = "embedded-visualizer.py")]
 
diff --git a/tests/rustdoc-ui/issues/issue-105742.rs b/tests/rustdoc-ui/issues/issue-105742.rs
index 8f4172c0cbb..1fbb70c7808 100644
--- a/tests/rustdoc-ui/issues/issue-105742.rs
+++ b/tests/rustdoc-ui/issues/issue-105742.rs
@@ -19,6 +19,8 @@ pub trait SVec: Index<
     //~| missing generics for associated type `SVec::Item`
     //~| missing generics for associated type `SVec::Item`
     //~| missing generics for associated type `SVec::Item`
+    //~| missing generics for associated type `SVec::Item`
+    //~| missing generics for associated type `SVec::Item`
     Output = <Index<<Self as SVec>::Item,
     //~^ expected 1 lifetime argument
     //~| expected 1 generic argument
@@ -26,6 +28,8 @@ pub trait SVec: Index<
     //~| missing generics for associated type `SVec::Item`
     //~| missing generics for associated type `SVec::Item`
     //~| missing generics for associated type `SVec::Item`
+    //~| missing generics for associated type `SVec::Item`
+    //~| missing generics for associated type `SVec::Item`
     Output = <Self as SVec>::Item> as SVec>::Item,
     //~^ expected 1 lifetime argument
     //~| expected 1 generic argument
@@ -34,11 +38,15 @@ pub trait SVec: Index<
     //~| missing generics for associated type `SVec::Item`
     //~| missing generics for associated type `SVec::Item`
     //~| missing generics for associated type `SVec::Item`
+    //~| missing generics for associated type `SVec::Item`
+    //~| missing generics for associated type `SVec::Item`
     //~| expected 1 generic argument
     //~| missing generics for associated type `SVec::Item`
     //~| missing generics for associated type `SVec::Item`
     //~| missing generics for associated type `SVec::Item`
     //~| missing generics for associated type `SVec::Item`
+    //~| missing generics for associated type `SVec::Item`
+    //~| missing generics for associated type `SVec::Item`
 > {
     type Item<'a, T>;
 
diff --git a/tests/rustdoc-ui/issues/issue-105742.stderr b/tests/rustdoc-ui/issues/issue-105742.stderr
index cd53762ef9b..b63176c9149 100644
--- a/tests/rustdoc-ui/issues/issue-105742.stderr
+++ b/tests/rustdoc-ui/issues/issue-105742.stderr
@@ -5,7 +5,7 @@ LL |     <Self as SVec>::Item,
    |                     ^^^^ expected 1 lifetime argument
    |
 note: associated type defined here, with 1 lifetime parameter: `'a`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
@@ -21,7 +21,7 @@ LL |     <Self as SVec>::Item,
    |                     ^^^^ expected 1 generic argument
    |
 note: associated type defined here, with 1 generic parameter: `T`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
@@ -31,13 +31,13 @@ LL |     <Self as SVec>::Item<T>,
    |                         +++
 
 error[E0107]: missing generics for associated type `SVec::Item`
-  --> $DIR/issue-105742.rs:22:37
+  --> $DIR/issue-105742.rs:24:37
    |
 LL |     Output = <Index<<Self as SVec>::Item,
    |                                     ^^^^ expected 1 lifetime argument
    |
 note: associated type defined here, with 1 lifetime parameter: `'a`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
@@ -47,13 +47,13 @@ LL |     Output = <Index<<Self as SVec>::Item<'a>,
    |                                         ++++
 
 error[E0107]: missing generics for associated type `SVec::Item`
-  --> $DIR/issue-105742.rs:22:37
+  --> $DIR/issue-105742.rs:24:37
    |
 LL |     Output = <Index<<Self as SVec>::Item,
    |                                     ^^^^ expected 1 generic argument
    |
 note: associated type defined here, with 1 generic parameter: `T`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
@@ -63,13 +63,13 @@ LL |     Output = <Index<<Self as SVec>::Item<T>,
    |                                         +++
 
 error[E0107]: missing generics for associated type `SVec::Item`
-  --> $DIR/issue-105742.rs:29:30
+  --> $DIR/issue-105742.rs:33:30
    |
 LL |     Output = <Self as SVec>::Item> as SVec>::Item,
    |                              ^^^^ expected 1 lifetime argument
    |
 note: associated type defined here, with 1 lifetime parameter: `'a`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
@@ -79,13 +79,13 @@ LL |     Output = <Self as SVec>::Item<'a>> as SVec>::Item,
    |                                  ++++
 
 error[E0107]: missing generics for associated type `SVec::Item`
-  --> $DIR/issue-105742.rs:29:30
+  --> $DIR/issue-105742.rs:33:30
    |
 LL |     Output = <Self as SVec>::Item> as SVec>::Item,
    |                              ^^^^ expected 1 generic argument
    |
 note: associated type defined here, with 1 generic parameter: `T`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
@@ -95,13 +95,13 @@ LL |     Output = <Self as SVec>::Item<T>> as SVec>::Item,
    |                                  +++
 
 error[E0107]: missing generics for associated type `SVec::Item`
-  --> $DIR/issue-105742.rs:29:46
+  --> $DIR/issue-105742.rs:33:46
    |
 LL |     Output = <Self as SVec>::Item> as SVec>::Item,
    |                                              ^^^^ expected 1 lifetime argument
    |
 note: associated type defined here, with 1 lifetime parameter: `'a`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
@@ -111,13 +111,13 @@ LL |     Output = <Self as SVec>::Item> as SVec>::Item<'a>,
    |                                                  ++++
 
 error[E0107]: missing generics for associated type `SVec::Item`
-  --> $DIR/issue-105742.rs:29:46
+  --> $DIR/issue-105742.rs:33:46
    |
 LL |     Output = <Self as SVec>::Item> as SVec>::Item,
    |                                              ^^^^ expected 1 generic argument
    |
 note: associated type defined here, with 1 generic parameter: `T`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
@@ -133,7 +133,7 @@ LL | pub fn next<'a, T>(s: &'a mut dyn SVec<Item = T, Output = T>) {
    |                                        ^^^^ expected 1 lifetime argument
    |
 note: associated type defined here, with 1 lifetime parameter: `'a`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
@@ -149,7 +149,7 @@ LL | pub fn next<'a, T>(s: &'a mut dyn SVec<Item = T, Output = T>) {
    |                                        ^^^^ expected 1 generic argument
    |
 note: associated type defined here, with 1 generic parameter: `T`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
@@ -165,7 +165,7 @@ LL |     <Self as SVec>::Item,
    |                     ^^^^ expected 1 lifetime argument
    |
 note: associated type defined here, with 1 lifetime parameter: `'a`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
@@ -181,7 +181,7 @@ LL |     <Self as SVec>::Item,
    |                     ^^^^ expected 1 generic argument
    |
 note: associated type defined here, with 1 generic parameter: `T`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
@@ -191,13 +191,13 @@ LL |     <Self as SVec>::Item<T>,
    |                         +++
 
 error[E0107]: missing generics for associated type `SVec::Item`
-  --> $DIR/issue-105742.rs:22:37
+  --> $DIR/issue-105742.rs:24:37
    |
 LL |     Output = <Index<<Self as SVec>::Item,
    |                                     ^^^^ expected 1 lifetime argument
    |
 note: associated type defined here, with 1 lifetime parameter: `'a`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
@@ -207,13 +207,13 @@ LL |     Output = <Index<<Self as SVec>::Item<'a>,
    |                                         ++++
 
 error[E0107]: missing generics for associated type `SVec::Item`
-  --> $DIR/issue-105742.rs:22:37
+  --> $DIR/issue-105742.rs:24:37
    |
 LL |     Output = <Index<<Self as SVec>::Item,
    |                                     ^^^^ expected 1 generic argument
    |
 note: associated type defined here, with 1 generic parameter: `T`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
@@ -223,13 +223,13 @@ LL |     Output = <Index<<Self as SVec>::Item<T>,
    |                                         +++
 
 error[E0107]: missing generics for associated type `SVec::Item`
-  --> $DIR/issue-105742.rs:29:30
+  --> $DIR/issue-105742.rs:33:30
    |
 LL |     Output = <Self as SVec>::Item> as SVec>::Item,
    |                              ^^^^ expected 1 lifetime argument
    |
 note: associated type defined here, with 1 lifetime parameter: `'a`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
@@ -239,13 +239,13 @@ LL |     Output = <Self as SVec>::Item<'a>> as SVec>::Item,
    |                                  ++++
 
 error[E0107]: missing generics for associated type `SVec::Item`
-  --> $DIR/issue-105742.rs:29:30
+  --> $DIR/issue-105742.rs:33:30
    |
 LL |     Output = <Self as SVec>::Item> as SVec>::Item,
    |                              ^^^^ expected 1 generic argument
    |
 note: associated type defined here, with 1 generic parameter: `T`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
@@ -255,13 +255,13 @@ LL |     Output = <Self as SVec>::Item<T>> as SVec>::Item,
    |                                  +++
 
 error[E0107]: missing generics for associated type `SVec::Item`
-  --> $DIR/issue-105742.rs:29:46
+  --> $DIR/issue-105742.rs:33:46
    |
 LL |     Output = <Self as SVec>::Item> as SVec>::Item,
    |                                              ^^^^ expected 1 lifetime argument
    |
 note: associated type defined here, with 1 lifetime parameter: `'a`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
@@ -271,13 +271,13 @@ LL |     Output = <Self as SVec>::Item> as SVec>::Item<'a>,
    |                                                  ++++
 
 error[E0107]: missing generics for associated type `SVec::Item`
-  --> $DIR/issue-105742.rs:29:46
+  --> $DIR/issue-105742.rs:33:46
    |
 LL |     Output = <Self as SVec>::Item> as SVec>::Item,
    |                                              ^^^^ expected 1 generic argument
    |
 note: associated type defined here, with 1 generic parameter: `T`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
@@ -317,13 +317,141 @@ LL | |  > {
    | |__^ ...because it uses `Self` as a type parameter
 
 error[E0107]: missing generics for associated type `SVec::Item`
-  --> $DIR/issue-105742.rs:45:38
+  --> $DIR/issue-105742.rs:15:21
+   |
+LL |     <Self as SVec>::Item,
+   |                     ^^^^ expected 1 lifetime argument
+   |
+note: associated type defined here, with 1 lifetime parameter: `'a`
+  --> $DIR/issue-105742.rs:51:10
+   |
+LL |     type Item<'a, T>;
+   |          ^^^^ --
+help: add missing lifetime argument
+   |
+LL |     <Self as SVec>::Item<'a>,
+   |                         ++++
+
+error[E0107]: missing generics for associated type `SVec::Item`
+  --> $DIR/issue-105742.rs:15:21
+   |
+LL |     <Self as SVec>::Item,
+   |                     ^^^^ expected 1 generic argument
+   |
+note: associated type defined here, with 1 generic parameter: `T`
+  --> $DIR/issue-105742.rs:51:10
+   |
+LL |     type Item<'a, T>;
+   |          ^^^^     -
+help: add missing generic argument
+   |
+LL |     <Self as SVec>::Item<T>,
+   |                         +++
+
+error[E0107]: missing generics for associated type `SVec::Item`
+  --> $DIR/issue-105742.rs:24:37
+   |
+LL |     Output = <Index<<Self as SVec>::Item,
+   |                                     ^^^^ expected 1 lifetime argument
+   |
+note: associated type defined here, with 1 lifetime parameter: `'a`
+  --> $DIR/issue-105742.rs:51:10
+   |
+LL |     type Item<'a, T>;
+   |          ^^^^ --
+help: add missing lifetime argument
+   |
+LL |     Output = <Index<<Self as SVec>::Item<'a>,
+   |                                         ++++
+
+error[E0107]: missing generics for associated type `SVec::Item`
+  --> $DIR/issue-105742.rs:24:37
+   |
+LL |     Output = <Index<<Self as SVec>::Item,
+   |                                     ^^^^ expected 1 generic argument
+   |
+note: associated type defined here, with 1 generic parameter: `T`
+  --> $DIR/issue-105742.rs:51:10
+   |
+LL |     type Item<'a, T>;
+   |          ^^^^     -
+help: add missing generic argument
+   |
+LL |     Output = <Index<<Self as SVec>::Item<T>,
+   |                                         +++
+
+error[E0107]: missing generics for associated type `SVec::Item`
+  --> $DIR/issue-105742.rs:33:30
+   |
+LL |     Output = <Self as SVec>::Item> as SVec>::Item,
+   |                              ^^^^ expected 1 lifetime argument
+   |
+note: associated type defined here, with 1 lifetime parameter: `'a`
+  --> $DIR/issue-105742.rs:51:10
+   |
+LL |     type Item<'a, T>;
+   |          ^^^^ --
+help: add missing lifetime argument
+   |
+LL |     Output = <Self as SVec>::Item<'a>> as SVec>::Item,
+   |                                  ++++
+
+error[E0107]: missing generics for associated type `SVec::Item`
+  --> $DIR/issue-105742.rs:33:30
+   |
+LL |     Output = <Self as SVec>::Item> as SVec>::Item,
+   |                              ^^^^ expected 1 generic argument
+   |
+note: associated type defined here, with 1 generic parameter: `T`
+  --> $DIR/issue-105742.rs:51:10
+   |
+LL |     type Item<'a, T>;
+   |          ^^^^     -
+help: add missing generic argument
+   |
+LL |     Output = <Self as SVec>::Item<T>> as SVec>::Item,
+   |                                  +++
+
+error[E0107]: missing generics for associated type `SVec::Item`
+  --> $DIR/issue-105742.rs:33:46
+   |
+LL |     Output = <Self as SVec>::Item> as SVec>::Item,
+   |                                              ^^^^ expected 1 lifetime argument
+   |
+note: associated type defined here, with 1 lifetime parameter: `'a`
+  --> $DIR/issue-105742.rs:51:10
+   |
+LL |     type Item<'a, T>;
+   |          ^^^^ --
+help: add missing lifetime argument
+   |
+LL |     Output = <Self as SVec>::Item> as SVec>::Item<'a>,
+   |                                                  ++++
+
+error[E0107]: missing generics for associated type `SVec::Item`
+  --> $DIR/issue-105742.rs:33:46
+   |
+LL |     Output = <Self as SVec>::Item> as SVec>::Item,
+   |                                              ^^^^ expected 1 generic argument
+   |
+note: associated type defined here, with 1 generic parameter: `T`
+  --> $DIR/issue-105742.rs:51:10
+   |
+LL |     type Item<'a, T>;
+   |          ^^^^     -
+help: add missing generic argument
+   |
+LL |     Output = <Self as SVec>::Item> as SVec>::Item<T>,
+   |                                                  +++
+
+error[E0107]: missing generics for associated type `SVec::Item`
+  --> $DIR/issue-105742.rs:53:38
    |
 LL |     fn len(&self) -> <Self as SVec>::Item;
    |                                      ^^^^ expected 1 lifetime argument
    |
 note: associated type defined here, with 1 lifetime parameter: `'a`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^ --
@@ -333,13 +461,13 @@ LL |     fn len(&self) -> <Self as SVec>::Item<'_>;
    |                                          ++++
 
 error[E0107]: missing generics for associated type `SVec::Item`
-  --> $DIR/issue-105742.rs:45:38
+  --> $DIR/issue-105742.rs:53:38
    |
 LL |     fn len(&self) -> <Self as SVec>::Item;
    |                                      ^^^^ expected 1 generic argument
    |
 note: associated type defined here, with 1 generic parameter: `T`
-  --> $DIR/issue-105742.rs:43:10
+  --> $DIR/issue-105742.rs:51:10
    |
 LL |     type Item<'a, T>;
    |          ^^^^     -
@@ -348,7 +476,7 @@ help: add missing generic argument
 LL |     fn len(&self) -> <Self as SVec>::Item<T>;
    |                                          +++
 
-error: aborting due to 21 previous errors
+error: aborting due to 29 previous errors
 
 Some errors have detailed explanations: E0038, E0107.
 For more information about an error, try `rustc --explain E0038`.
diff --git a/tests/ui/associated-type-bounds/duplicate.rs b/tests/ui/associated-type-bounds/duplicate.rs
index f67410986e5..4b8bf52c374 100644
--- a/tests/ui/associated-type-bounds/duplicate.rs
+++ b/tests/ui/associated-type-bounds/duplicate.rs
@@ -193,10 +193,13 @@ trait TRI3<T: Iterator<Item: 'static, Item: 'static>> {}
 //~^ ERROR the value of the associated type `Item` (from trait `Iterator`) is already specified [E0719]
 trait TRS1: Iterator<Item: Copy, Item: Send> {}
 //~^ ERROR the value of the associated type `Item` (from trait `Iterator`) is already specified [E0719]
+//~| ERROR the value of the associated type `Item` (from trait `Iterator`) is already specified [E0719]
 trait TRS2: Iterator<Item: Copy, Item: Copy> {}
 //~^ ERROR the value of the associated type `Item` (from trait `Iterator`) is already specified [E0719]
+//~| ERROR the value of the associated type `Item` (from trait `Iterator`) is already specified [E0719]
 trait TRS3: Iterator<Item: 'static, Item: 'static> {}
 //~^ ERROR the value of the associated type `Item` (from trait `Iterator`) is already specified [E0719]
+//~| ERROR the value of the associated type `Item` (from trait `Iterator`) is already specified [E0719]
 trait TRW1<T>
 where
     T: Iterator<Item: Copy, Item: Send>,
diff --git a/tests/ui/associated-type-bounds/duplicate.stderr b/tests/ui/associated-type-bounds/duplicate.stderr
index c3061327f56..08721eff7b0 100644
--- a/tests/ui/associated-type-bounds/duplicate.stderr
+++ b/tests/ui/associated-type-bounds/duplicate.stderr
@@ -367,7 +367,23 @@ LL | trait TRS1: Iterator<Item: Copy, Item: Send> {}
    |                      `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:196:34
+  --> $DIR/duplicate.rs:194:34
+   |
+LL | trait TRS1: Iterator<Item: Copy, Item: Send> {}
+   |                      ----------  ^^^^^^^^^^ re-bound here
+   |                      |
+   |                      `Item` bound here first
+
+error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
+  --> $DIR/duplicate.rs:197:34
+   |
+LL | trait TRS2: Iterator<Item: Copy, Item: Copy> {}
+   |                      ----------  ^^^^^^^^^^ re-bound here
+   |                      |
+   |                      `Item` bound here first
+
+error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
+  --> $DIR/duplicate.rs:197:34
    |
 LL | trait TRS2: Iterator<Item: Copy, Item: Copy> {}
    |                      ----------  ^^^^^^^^^^ re-bound here
@@ -375,7 +391,15 @@ LL | trait TRS2: Iterator<Item: Copy, Item: Copy> {}
    |                      `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:198:37
+  --> $DIR/duplicate.rs:200:37
+   |
+LL | trait TRS3: Iterator<Item: 'static, Item: 'static> {}
+   |                      -------------  ^^^^^^^^^^^^^ re-bound here
+   |                      |
+   |                      `Item` bound here first
+
+error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
+  --> $DIR/duplicate.rs:200:37
    |
 LL | trait TRS3: Iterator<Item: 'static, Item: 'static> {}
    |                      -------------  ^^^^^^^^^^^^^ re-bound here
@@ -383,7 +407,7 @@ LL | trait TRS3: Iterator<Item: 'static, Item: 'static> {}
    |                      `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:202:29
+  --> $DIR/duplicate.rs:205:29
    |
 LL |     T: Iterator<Item: Copy, Item: Send>,
    |                 ----------  ^^^^^^^^^^ re-bound here
@@ -391,7 +415,7 @@ LL |     T: Iterator<Item: Copy, Item: Send>,
    |                 `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:208:29
+  --> $DIR/duplicate.rs:211:29
    |
 LL |     T: Iterator<Item: Copy, Item: Copy>,
    |                 ----------  ^^^^^^^^^^ re-bound here
@@ -399,7 +423,7 @@ LL |     T: Iterator<Item: Copy, Item: Copy>,
    |                 `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:214:32
+  --> $DIR/duplicate.rs:217:32
    |
 LL |     T: Iterator<Item: 'static, Item: 'static>,
    |                 -------------  ^^^^^^^^^^^^^ re-bound here
@@ -407,7 +431,7 @@ LL |     T: Iterator<Item: 'static, Item: 'static>,
    |                 `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:220:32
+  --> $DIR/duplicate.rs:223:32
    |
 LL |     Self: Iterator<Item: Copy, Item: Send>,
    |                    ----------  ^^^^^^^^^^ re-bound here
@@ -415,7 +439,7 @@ LL |     Self: Iterator<Item: Copy, Item: Send>,
    |                    `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:220:32
+  --> $DIR/duplicate.rs:223:32
    |
 LL |     Self: Iterator<Item: Copy, Item: Send>,
    |                    ----------  ^^^^^^^^^^ re-bound here
@@ -423,7 +447,7 @@ LL |     Self: Iterator<Item: Copy, Item: Send>,
    |                    `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:227:32
+  --> $DIR/duplicate.rs:230:32
    |
 LL |     Self: Iterator<Item: Copy, Item: Copy>,
    |                    ----------  ^^^^^^^^^^ re-bound here
@@ -431,7 +455,7 @@ LL |     Self: Iterator<Item: Copy, Item: Copy>,
    |                    `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:227:32
+  --> $DIR/duplicate.rs:230:32
    |
 LL |     Self: Iterator<Item: Copy, Item: Copy>,
    |                    ----------  ^^^^^^^^^^ re-bound here
@@ -439,7 +463,7 @@ LL |     Self: Iterator<Item: Copy, Item: Copy>,
    |                    `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:234:35
+  --> $DIR/duplicate.rs:237:35
    |
 LL |     Self: Iterator<Item: 'static, Item: 'static>,
    |                    -------------  ^^^^^^^^^^^^^ re-bound here
@@ -447,7 +471,7 @@ LL |     Self: Iterator<Item: 'static, Item: 'static>,
    |                    `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:234:35
+  --> $DIR/duplicate.rs:237:35
    |
 LL |     Self: Iterator<Item: 'static, Item: 'static>,
    |                    -------------  ^^^^^^^^^^^^^ re-bound here
@@ -455,7 +479,7 @@ LL |     Self: Iterator<Item: 'static, Item: 'static>,
    |                    `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:252:40
+  --> $DIR/duplicate.rs:255:40
    |
 LL | type TADyn1 = dyn Iterator<Item: Copy, Item: Send>;
    |                            ----------  ^^^^^^^^^^ re-bound here
@@ -463,7 +487,7 @@ LL | type TADyn1 = dyn Iterator<Item: Copy, Item: Send>;
    |                            `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:254:44
+  --> $DIR/duplicate.rs:257:44
    |
 LL | type TADyn2 = Box<dyn Iterator<Item: Copy, Item: Copy>>;
    |                                ----------  ^^^^^^^^^^ re-bound here
@@ -471,7 +495,7 @@ LL | type TADyn2 = Box<dyn Iterator<Item: Copy, Item: Copy>>;
    |                                `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:256:43
+  --> $DIR/duplicate.rs:259:43
    |
 LL | type TADyn3 = dyn Iterator<Item: 'static, Item: 'static>;
    |                            -------------  ^^^^^^^^^^^^^ re-bound here
@@ -479,7 +503,7 @@ LL | type TADyn3 = dyn Iterator<Item: 'static, Item: 'static>;
    |                            `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:240:34
+  --> $DIR/duplicate.rs:243:34
    |
 LL |     type A: Iterator<Item: Copy, Item: Send>;
    |                      ----------  ^^^^^^^^^^ re-bound here
@@ -487,7 +511,7 @@ LL |     type A: Iterator<Item: Copy, Item: Send>;
    |                      `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:244:34
+  --> $DIR/duplicate.rs:247:34
    |
 LL |     type A: Iterator<Item: Copy, Item: Copy>;
    |                      ----------  ^^^^^^^^^^ re-bound here
@@ -495,13 +519,13 @@ LL |     type A: Iterator<Item: Copy, Item: Copy>;
    |                      `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/duplicate.rs:248:37
+  --> $DIR/duplicate.rs:251:37
    |
 LL |     type A: Iterator<Item: 'static, Item: 'static>;
    |                      -------------  ^^^^^^^^^^^^^ re-bound here
    |                      |
    |                      `Item` bound here first
 
-error: aborting due to 63 previous errors
+error: aborting due to 66 previous errors
 
 For more information about this error, try `rustc --explain E0719`.
diff --git a/tests/ui/associated-type-bounds/return-type-notation/bad-inputs-and-output.rs b/tests/ui/associated-type-bounds/return-type-notation/bad-inputs-and-output.rs
index 79cee55177b..58ce41d1a89 100644
--- a/tests/ui/associated-type-bounds/return-type-notation/bad-inputs-and-output.rs
+++ b/tests/ui/associated-type-bounds/return-type-notation/bad-inputs-and-output.rs
@@ -2,7 +2,6 @@
 
 #![feature(return_type_notation, async_fn_in_trait)]
 //~^ WARN the feature `return_type_notation` is incomplete
-//~| WARN the feature `async_fn_in_trait` is incomplete
 
 trait Trait {
     async fn method() {}
diff --git a/tests/ui/associated-type-bounds/return-type-notation/bad-inputs-and-output.stderr b/tests/ui/associated-type-bounds/return-type-notation/bad-inputs-and-output.stderr
index b23e0f791ea..95ef7d82fca 100644
--- a/tests/ui/associated-type-bounds/return-type-notation/bad-inputs-and-output.stderr
+++ b/tests/ui/associated-type-bounds/return-type-notation/bad-inputs-and-output.stderr
@@ -1,11 +1,11 @@
 error: return type notation uses `()` instead of `(..)` for elided arguments
-  --> $DIR/bad-inputs-and-output.rs:19:24
+  --> $DIR/bad-inputs-and-output.rs:18:24
    |
 LL | fn baz<T: Trait<method(..): Send>>() {}
    |                        ^^ help: remove the `..`
 
 error[E0658]: associated type bounds are unstable
-  --> $DIR/bad-inputs-and-output.rs:11:17
+  --> $DIR/bad-inputs-and-output.rs:10:17
    |
 LL | fn foo<T: Trait<method(i32): Send>>() {}
    |                 ^^^^^^^^^^^^^^^^^
@@ -14,7 +14,7 @@ LL | fn foo<T: Trait<method(i32): Send>>() {}
    = help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
 
 error[E0658]: associated type bounds are unstable
-  --> $DIR/bad-inputs-and-output.rs:15:17
+  --> $DIR/bad-inputs-and-output.rs:14:17
    |
 LL | fn bar<T: Trait<method() -> (): Send>>() {}
    |                 ^^^^^^^^^^^^^^^^^^^^
@@ -31,26 +31,18 @@ LL | #![feature(return_type_notation, async_fn_in_trait)]
    = note: see issue #109417 <https://github.com/rust-lang/rust/issues/109417> for more information
    = note: `#[warn(incomplete_features)]` on by default
 
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/bad-inputs-and-output.rs:3:34
-   |
-LL | #![feature(return_type_notation, async_fn_in_trait)]
-   |                                  ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-
 error: argument types not allowed with return type notation
-  --> $DIR/bad-inputs-and-output.rs:11:23
+  --> $DIR/bad-inputs-and-output.rs:10:23
    |
 LL | fn foo<T: Trait<method(i32): Send>>() {}
    |                       ^^^^^ help: remove the input types: `()`
 
 error: return type not allowed with return type notation
-  --> $DIR/bad-inputs-and-output.rs:15:25
+  --> $DIR/bad-inputs-and-output.rs:14:25
    |
 LL | fn bar<T: Trait<method() -> (): Send>>() {}
    |                         ^^^^^^ help: remove the return type
 
-error: aborting due to 5 previous errors; 2 warnings emitted
+error: aborting due to 5 previous errors; 1 warning emitted
 
 For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/associated-type-bounds/return-type-notation/basic.rs b/tests/ui/associated-type-bounds/return-type-notation/basic.rs
index 0b7530b65d7..edc6a8e4caf 100644
--- a/tests/ui/associated-type-bounds/return-type-notation/basic.rs
+++ b/tests/ui/associated-type-bounds/return-type-notation/basic.rs
@@ -4,7 +4,6 @@
 
 #![feature(return_type_notation, async_fn_in_trait)]
 //~^ WARN the feature `return_type_notation` is incomplete
-//~| WARN the feature `async_fn_in_trait` is incomplete
 
 trait Foo {
     async fn method() -> Result<(), ()>;
diff --git a/tests/ui/associated-type-bounds/return-type-notation/basic.with.stderr b/tests/ui/associated-type-bounds/return-type-notation/basic.with.stderr
index 722c774cb33..9962f4706b3 100644
--- a/tests/ui/associated-type-bounds/return-type-notation/basic.with.stderr
+++ b/tests/ui/associated-type-bounds/return-type-notation/basic.with.stderr
@@ -7,13 +7,5 @@ LL | #![feature(return_type_notation, async_fn_in_trait)]
    = note: see issue #109417 <https://github.com/rust-lang/rust/issues/109417> for more information
    = note: `#[warn(incomplete_features)]` on by default
 
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/basic.rs:5:34
-   |
-LL | #![feature(return_type_notation, async_fn_in_trait)]
-   |                                  ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-
-warning: 2 warnings emitted
+warning: 1 warning emitted
 
diff --git a/tests/ui/associated-type-bounds/return-type-notation/basic.without.stderr b/tests/ui/associated-type-bounds/return-type-notation/basic.without.stderr
index 1645d8c2650..c2da4f57696 100644
--- a/tests/ui/associated-type-bounds/return-type-notation/basic.without.stderr
+++ b/tests/ui/associated-type-bounds/return-type-notation/basic.without.stderr
@@ -7,31 +7,23 @@ LL | #![feature(return_type_notation, async_fn_in_trait)]
    = note: see issue #109417 <https://github.com/rust-lang/rust/issues/109417> for more information
    = note: `#[warn(incomplete_features)]` on by default
 
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/basic.rs:5:34
-   |
-LL | #![feature(return_type_notation, async_fn_in_trait)]
-   |                                  ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-
 error: future cannot be sent between threads safely
-  --> $DIR/basic.rs:24:13
+  --> $DIR/basic.rs:23:13
    |
 LL |     is_send(foo::<T>());
    |             ^^^^^^^^^^ future returned by `foo` is not `Send`
    |
    = help: within `impl Future<Output = Result<(), ()>>`, the trait `Send` is not implemented for `impl Future<Output = Result<(), ()>>`
 note: future is not `Send` as it awaits another future which is not `Send`
-  --> $DIR/basic.rs:14:5
+  --> $DIR/basic.rs:13:5
    |
 LL |     T::method().await?;
    |     ^^^^^^^^^^^ await occurs here on type `impl Future<Output = Result<(), ()>>`, which is not `Send`
 note: required by a bound in `is_send`
-  --> $DIR/basic.rs:18:20
+  --> $DIR/basic.rs:17:20
    |
 LL | fn is_send(_: impl Send) {}
    |                    ^^^^ required by this bound in `is_send`
 
-error: aborting due to previous error; 2 warnings emitted
+error: aborting due to previous error; 1 warning emitted
 
diff --git a/tests/ui/associated-type-bounds/return-type-notation/equality.rs b/tests/ui/associated-type-bounds/return-type-notation/equality.rs
index 75f757e9025..6884305d7b3 100644
--- a/tests/ui/associated-type-bounds/return-type-notation/equality.rs
+++ b/tests/ui/associated-type-bounds/return-type-notation/equality.rs
@@ -2,7 +2,6 @@
 
 #![feature(return_type_notation, async_fn_in_trait)]
 //~^ WARN the feature `return_type_notation` is incomplete
-//~| WARN the feature `async_fn_in_trait` is incomplete
 
 use std::future::Future;
 
diff --git a/tests/ui/associated-type-bounds/return-type-notation/equality.stderr b/tests/ui/associated-type-bounds/return-type-notation/equality.stderr
index c5b2e5710d4..490bfdc4c3c 100644
--- a/tests/ui/associated-type-bounds/return-type-notation/equality.stderr
+++ b/tests/ui/associated-type-bounds/return-type-notation/equality.stderr
@@ -7,19 +7,11 @@ LL | #![feature(return_type_notation, async_fn_in_trait)]
    = note: see issue #109417 <https://github.com/rust-lang/rust/issues/109417> for more information
    = note: `#[warn(incomplete_features)]` on by default
 
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/equality.rs:3:34
-   |
-LL | #![feature(return_type_notation, async_fn_in_trait)]
-   |                                  ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-
 error: return type notation is not allowed to use type equality
-  --> $DIR/equality.rs:13:18
+  --> $DIR/equality.rs:12:18
    |
 LL | fn test<T: Trait<method() = Box<dyn Future<Output = ()>>>>() {}
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to previous error; 2 warnings emitted
+error: aborting due to previous error; 1 warning emitted
 
diff --git a/tests/ui/associated-type-bounds/return-type-notation/missing.rs b/tests/ui/associated-type-bounds/return-type-notation/missing.rs
index 7b98a5cdafd..b84b5a717b7 100644
--- a/tests/ui/associated-type-bounds/return-type-notation/missing.rs
+++ b/tests/ui/associated-type-bounds/return-type-notation/missing.rs
@@ -2,7 +2,6 @@
 
 #![feature(return_type_notation, async_fn_in_trait)]
 //~^ WARN the feature `return_type_notation` is incomplete
-//~| WARN the feature `async_fn_in_trait` is incomplete
 
 trait Trait {
     async fn method() {}
diff --git a/tests/ui/associated-type-bounds/return-type-notation/missing.stderr b/tests/ui/associated-type-bounds/return-type-notation/missing.stderr
index 34f5bda884d..954d9f74767 100644
--- a/tests/ui/associated-type-bounds/return-type-notation/missing.stderr
+++ b/tests/ui/associated-type-bounds/return-type-notation/missing.stderr
@@ -7,19 +7,11 @@ LL | #![feature(return_type_notation, async_fn_in_trait)]
    = note: see issue #109417 <https://github.com/rust-lang/rust/issues/109417> for more information
    = note: `#[warn(incomplete_features)]` on by default
 
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/missing.rs:3:34
-   |
-LL | #![feature(return_type_notation, async_fn_in_trait)]
-   |                                  ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-
 error: cannot find associated function `methid` in trait `Trait`
-  --> $DIR/missing.rs:11:17
+  --> $DIR/missing.rs:10:17
    |
 LL | fn bar<T: Trait<methid(): Send>>() {}
    |                 ^^^^^^^^^^^^^^
 
-error: aborting due to previous error; 2 warnings emitted
+error: aborting due to previous error; 1 warning emitted
 
diff --git a/tests/ui/associated-type-bounds/supertrait-defines-ty.rs b/tests/ui/associated-type-bounds/supertrait-defines-ty.rs
new file mode 100644
index 00000000000..b6f37cb908e
--- /dev/null
+++ b/tests/ui/associated-type-bounds/supertrait-defines-ty.rs
@@ -0,0 +1,26 @@
+// check-pass
+
+// Make sure that we don't look into associated type bounds when looking for
+// supertraits that define an associated type. Fixes #76593.
+
+#![feature(associated_type_bounds)]
+
+trait Load: Sized {
+    type Blob;
+}
+
+trait Primitive: Load<Blob = Self> {}
+
+trait BlobPtr: Primitive {}
+
+trait CleanPtr: Load<Blob: BlobPtr> {
+    fn to_blob(&self) -> Self::Blob;
+}
+
+impl Load for () {
+    type Blob = Self;
+}
+impl Primitive for () {}
+impl BlobPtr for () {}
+
+fn main() {}
diff --git a/tests/ui/async-await/in-trait/async-default-fn-overridden.current.stderr b/tests/ui/async-await/in-trait/async-default-fn-overridden.current.stderr
deleted file mode 100644
index 2142ee232ca..00000000000
--- a/tests/ui/async-await/in-trait/async-default-fn-overridden.current.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/async-default-fn-overridden.rs:6:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-warning: 1 warning emitted
-
diff --git a/tests/ui/async-await/in-trait/async-default-fn-overridden.next.stderr b/tests/ui/async-await/in-trait/async-default-fn-overridden.next.stderr
deleted file mode 100644
index 2142ee232ca..00000000000
--- a/tests/ui/async-await/in-trait/async-default-fn-overridden.next.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/async-default-fn-overridden.rs:6:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-warning: 1 warning emitted
-
diff --git a/tests/ui/async-await/in-trait/async-default-fn-overridden.rs b/tests/ui/async-await/in-trait/async-default-fn-overridden.rs
index dd1af93d706..99c3ba6a3c2 100644
--- a/tests/ui/async-await/in-trait/async-default-fn-overridden.rs
+++ b/tests/ui/async-await/in-trait/async-default-fn-overridden.rs
@@ -4,7 +4,6 @@
 // revisions: current next
 
 #![feature(async_fn_in_trait)]
-//~^ WARN the feature `async_fn_in_trait` is incomplete and may not be safe to use
 
 use std::future::Future;
 
diff --git a/tests/ui/async-await/in-trait/bad-signatures.current.stderr b/tests/ui/async-await/in-trait/bad-signatures.current.stderr
index 5a05b080c3e..ae590fb057f 100644
--- a/tests/ui/async-await/in-trait/bad-signatures.current.stderr
+++ b/tests/ui/async-await/in-trait/bad-signatures.current.stderr
@@ -1,11 +1,11 @@
 error: expected identifier, found keyword `self`
-  --> $DIR/bad-signatures.rs:9:23
+  --> $DIR/bad-signatures.rs:8:23
    |
 LL |     async fn bar(&abc self);
    |                       ^^^^ expected identifier, found keyword
 
 error: expected one of `:`, `@`, or `|`, found keyword `self`
-  --> $DIR/bad-signatures.rs:9:23
+  --> $DIR/bad-signatures.rs:8:23
    |
 LL |     async fn bar(&abc self);
    |                  -----^^^^
@@ -13,14 +13,5 @@ LL |     async fn bar(&abc self);
    |                  |    expected one of `:`, `@`, or `|`
    |                  help: declare the type after the parameter binding: `<identifier>: <type>`
 
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/bad-signatures.rs:5:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-error: aborting due to 2 previous errors; 1 warning emitted
+error: aborting due to 2 previous errors
 
diff --git a/tests/ui/async-await/in-trait/bad-signatures.next.stderr b/tests/ui/async-await/in-trait/bad-signatures.next.stderr
index 5a05b080c3e..ae590fb057f 100644
--- a/tests/ui/async-await/in-trait/bad-signatures.next.stderr
+++ b/tests/ui/async-await/in-trait/bad-signatures.next.stderr
@@ -1,11 +1,11 @@
 error: expected identifier, found keyword `self`
-  --> $DIR/bad-signatures.rs:9:23
+  --> $DIR/bad-signatures.rs:8:23
    |
 LL |     async fn bar(&abc self);
    |                       ^^^^ expected identifier, found keyword
 
 error: expected one of `:`, `@`, or `|`, found keyword `self`
-  --> $DIR/bad-signatures.rs:9:23
+  --> $DIR/bad-signatures.rs:8:23
    |
 LL |     async fn bar(&abc self);
    |                  -----^^^^
@@ -13,14 +13,5 @@ LL |     async fn bar(&abc self);
    |                  |    expected one of `:`, `@`, or `|`
    |                  help: declare the type after the parameter binding: `<identifier>: <type>`
 
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/bad-signatures.rs:5:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-error: aborting due to 2 previous errors; 1 warning emitted
+error: aborting due to 2 previous errors
 
diff --git a/tests/ui/async-await/in-trait/bad-signatures.rs b/tests/ui/async-await/in-trait/bad-signatures.rs
index e0093be8cb3..4baddd8ccb8 100644
--- a/tests/ui/async-await/in-trait/bad-signatures.rs
+++ b/tests/ui/async-await/in-trait/bad-signatures.rs
@@ -3,7 +3,6 @@
 // revisions: current next
 
 #![feature(async_fn_in_trait)]
-//~^ WARN the feature `async_fn_in_trait` is incomplete
 
 trait MyTrait {
     async fn bar(&abc self);
diff --git a/tests/ui/async-await/in-trait/dont-project-to-specializable-projection.current.stderr b/tests/ui/async-await/in-trait/dont-project-to-specializable-projection.current.stderr
index 1e67cdca248..eec5ab06539 100644
--- a/tests/ui/async-await/in-trait/dont-project-to-specializable-projection.current.stderr
+++ b/tests/ui/async-await/in-trait/dont-project-to-specializable-projection.current.stderr
@@ -1,12 +1,3 @@
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/dont-project-to-specializable-projection.rs:6:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 error: async associated function in trait cannot be specialized
   --> $DIR/dont-project-to-specializable-projection.rs:16:5
    |
@@ -15,5 +6,5 @@ LL |     default async fn foo(_: T) -> &'static str {
    |
    = note: specialization behaves in inconsistent and surprising ways with `#![feature(async_fn_in_trait)]`, and for now is disallowed
 
-error: aborting due to previous error; 1 warning emitted
+error: aborting due to previous error
 
diff --git a/tests/ui/async-await/in-trait/dont-project-to-specializable-projection.next.stderr b/tests/ui/async-await/in-trait/dont-project-to-specializable-projection.next.stderr
index fa89c6b77e0..25a7f3bb56a 100644
--- a/tests/ui/async-await/in-trait/dont-project-to-specializable-projection.next.stderr
+++ b/tests/ui/async-await/in-trait/dont-project-to-specializable-projection.next.stderr
@@ -1,12 +1,3 @@
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/dont-project-to-specializable-projection.rs:6:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0053]: method `foo` has an incompatible type for trait
   --> $DIR/dont-project-to-specializable-projection.rs:16:35
    |
@@ -29,6 +20,6 @@ LL |     default async fn foo(_: T) -> &'static str {
    |
    = note: specialization behaves in inconsistent and surprising ways with `#![feature(async_fn_in_trait)]`, and for now is disallowed
 
-error: aborting due to 2 previous errors; 1 warning emitted
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0053`.
diff --git a/tests/ui/async-await/in-trait/lifetime-mismatch.current.stderr b/tests/ui/async-await/in-trait/lifetime-mismatch.current.stderr
index 0e9477544a4..69e7c65ee3e 100644
--- a/tests/ui/async-await/in-trait/lifetime-mismatch.current.stderr
+++ b/tests/ui/async-await/in-trait/lifetime-mismatch.current.stderr
@@ -1,14 +1,5 @@
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/lifetime-mismatch.rs:5:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0195]: lifetime parameters or bounds on method `foo` do not match the trait declaration
-  --> $DIR/lifetime-mismatch.rs:14:17
+  --> $DIR/lifetime-mismatch.rs:13:17
    |
 LL |     async fn foo<'a>(&self);
    |                 ---- lifetimes in impl do not match this method in trait
@@ -16,6 +7,6 @@ LL |     async fn foo<'a>(&self);
 LL |     async fn foo(&self) {}
    |                 ^ lifetimes do not match method in trait
 
-error: aborting due to previous error; 1 warning emitted
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0195`.
diff --git a/tests/ui/async-await/in-trait/lifetime-mismatch.next.stderr b/tests/ui/async-await/in-trait/lifetime-mismatch.next.stderr
index 0e9477544a4..69e7c65ee3e 100644
--- a/tests/ui/async-await/in-trait/lifetime-mismatch.next.stderr
+++ b/tests/ui/async-await/in-trait/lifetime-mismatch.next.stderr
@@ -1,14 +1,5 @@
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/lifetime-mismatch.rs:5:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0195]: lifetime parameters or bounds on method `foo` do not match the trait declaration
-  --> $DIR/lifetime-mismatch.rs:14:17
+  --> $DIR/lifetime-mismatch.rs:13:17
    |
 LL |     async fn foo<'a>(&self);
    |                 ---- lifetimes in impl do not match this method in trait
@@ -16,6 +7,6 @@ LL |     async fn foo<'a>(&self);
 LL |     async fn foo(&self) {}
    |                 ^ lifetimes do not match method in trait
 
-error: aborting due to previous error; 1 warning emitted
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0195`.
diff --git a/tests/ui/async-await/in-trait/lifetime-mismatch.rs b/tests/ui/async-await/in-trait/lifetime-mismatch.rs
index 5ff5a01a1ee..46183f72bce 100644
--- a/tests/ui/async-await/in-trait/lifetime-mismatch.rs
+++ b/tests/ui/async-await/in-trait/lifetime-mismatch.rs
@@ -3,7 +3,6 @@
 // revisions: current next
 
 #![feature(async_fn_in_trait)]
-//~^ WARN the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
 
 trait MyTrait {
     async fn foo<'a>(&self);
diff --git a/tests/ui/async-await/in-trait/missing-send-bound.current.stderr b/tests/ui/async-await/in-trait/missing-send-bound.current.stderr
index 319ed582e27..9aa37f7437e 100644
--- a/tests/ui/async-await/in-trait/missing-send-bound.current.stderr
+++ b/tests/ui/async-await/in-trait/missing-send-bound.current.stderr
@@ -1,29 +1,20 @@
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/missing-send-bound.rs:5:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 error: future cannot be sent between threads safely
-  --> $DIR/missing-send-bound.rs:17:20
+  --> $DIR/missing-send-bound.rs:16:20
    |
 LL |     assert_is_send(test::<T>());
    |                    ^^^^^^^^^^^ future returned by `test` is not `Send`
    |
    = help: within `impl Future<Output = ()>`, the trait `Send` is not implemented for `impl Future<Output = ()>`
 note: future is not `Send` as it awaits another future which is not `Send`
-  --> $DIR/missing-send-bound.rs:13:5
+  --> $DIR/missing-send-bound.rs:12:5
    |
 LL |     T::bar().await;
    |     ^^^^^^^^ await occurs here on type `impl Future<Output = ()>`, which is not `Send`
 note: required by a bound in `assert_is_send`
-  --> $DIR/missing-send-bound.rs:21:27
+  --> $DIR/missing-send-bound.rs:20:27
    |
 LL | fn assert_is_send(_: impl Send) {}
    |                           ^^^^ required by this bound in `assert_is_send`
 
-error: aborting due to previous error; 1 warning emitted
+error: aborting due to previous error
 
diff --git a/tests/ui/async-await/in-trait/missing-send-bound.next.stderr b/tests/ui/async-await/in-trait/missing-send-bound.next.stderr
index 319ed582e27..9aa37f7437e 100644
--- a/tests/ui/async-await/in-trait/missing-send-bound.next.stderr
+++ b/tests/ui/async-await/in-trait/missing-send-bound.next.stderr
@@ -1,29 +1,20 @@
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/missing-send-bound.rs:5:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 error: future cannot be sent between threads safely
-  --> $DIR/missing-send-bound.rs:17:20
+  --> $DIR/missing-send-bound.rs:16:20
    |
 LL |     assert_is_send(test::<T>());
    |                    ^^^^^^^^^^^ future returned by `test` is not `Send`
    |
    = help: within `impl Future<Output = ()>`, the trait `Send` is not implemented for `impl Future<Output = ()>`
 note: future is not `Send` as it awaits another future which is not `Send`
-  --> $DIR/missing-send-bound.rs:13:5
+  --> $DIR/missing-send-bound.rs:12:5
    |
 LL |     T::bar().await;
    |     ^^^^^^^^ await occurs here on type `impl Future<Output = ()>`, which is not `Send`
 note: required by a bound in `assert_is_send`
-  --> $DIR/missing-send-bound.rs:21:27
+  --> $DIR/missing-send-bound.rs:20:27
    |
 LL | fn assert_is_send(_: impl Send) {}
    |                           ^^^^ required by this bound in `assert_is_send`
 
-error: aborting due to previous error; 1 warning emitted
+error: aborting due to previous error
 
diff --git a/tests/ui/async-await/in-trait/missing-send-bound.rs b/tests/ui/async-await/in-trait/missing-send-bound.rs
index 705fcf322f9..b602865cbb1 100644
--- a/tests/ui/async-await/in-trait/missing-send-bound.rs
+++ b/tests/ui/async-await/in-trait/missing-send-bound.rs
@@ -3,7 +3,6 @@
 // revisions: current next
 
 #![feature(async_fn_in_trait)]
-//~^ WARN the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
 
 trait Foo {
     async fn bar();
diff --git a/tests/ui/async-await/in-trait/object-safety.current.stderr b/tests/ui/async-await/in-trait/object-safety.current.stderr
index 90e049a9960..7f7ec39142c 100644
--- a/tests/ui/async-await/in-trait/object-safety.current.stderr
+++ b/tests/ui/async-await/in-trait/object-safety.current.stderr
@@ -1,20 +1,11 @@
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/object-safety.rs:5:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0038]: the trait `Foo` cannot be made into an object
-  --> $DIR/object-safety.rs:13:12
+  --> $DIR/object-safety.rs:12:12
    |
 LL |     let x: &dyn Foo = todo!();
    |            ^^^^^^^^ `Foo` cannot be made into an object
    |
 note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
-  --> $DIR/object-safety.rs:9:14
+  --> $DIR/object-safety.rs:8:14
    |
 LL | trait Foo {
    |       --- this trait cannot be made into an object...
@@ -22,6 +13,6 @@ LL |     async fn foo(&self);
    |              ^^^ ...because method `foo` is `async`
    = help: consider moving `foo` to another trait
 
-error: aborting due to previous error; 1 warning emitted
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/async-await/in-trait/object-safety.next.stderr b/tests/ui/async-await/in-trait/object-safety.next.stderr
index 90e049a9960..7f7ec39142c 100644
--- a/tests/ui/async-await/in-trait/object-safety.next.stderr
+++ b/tests/ui/async-await/in-trait/object-safety.next.stderr
@@ -1,20 +1,11 @@
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/object-safety.rs:5:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0038]: the trait `Foo` cannot be made into an object
-  --> $DIR/object-safety.rs:13:12
+  --> $DIR/object-safety.rs:12:12
    |
 LL |     let x: &dyn Foo = todo!();
    |            ^^^^^^^^ `Foo` cannot be made into an object
    |
 note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
-  --> $DIR/object-safety.rs:9:14
+  --> $DIR/object-safety.rs:8:14
    |
 LL | trait Foo {
    |       --- this trait cannot be made into an object...
@@ -22,6 +13,6 @@ LL |     async fn foo(&self);
    |              ^^^ ...because method `foo` is `async`
    = help: consider moving `foo` to another trait
 
-error: aborting due to previous error; 1 warning emitted
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/async-await/in-trait/object-safety.rs b/tests/ui/async-await/in-trait/object-safety.rs
index f67286a20a2..4edad1512e9 100644
--- a/tests/ui/async-await/in-trait/object-safety.rs
+++ b/tests/ui/async-await/in-trait/object-safety.rs
@@ -3,7 +3,6 @@
 // revisions: current next
 
 #![feature(async_fn_in_trait)]
-//~^ WARN the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
 
 trait Foo {
     async fn foo(&self);
diff --git a/tests/ui/async-await/in-trait/return-type-suggestion.current.stderr b/tests/ui/async-await/in-trait/return-type-suggestion.current.stderr
index a5efc757156..6a107d7beb8 100644
--- a/tests/ui/async-await/in-trait/return-type-suggestion.current.stderr
+++ b/tests/ui/async-await/in-trait/return-type-suggestion.current.stderr
@@ -1,14 +1,5 @@
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/return-type-suggestion.rs:5:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0308]: mismatched types
-  --> $DIR/return-type-suggestion.rs:10:9
+  --> $DIR/return-type-suggestion.rs:9:9
    |
 LL |         Ok(())
    |         ^^^^^^- help: consider using a semicolon here: `;`
@@ -18,6 +9,6 @@ LL |         Ok(())
    = note: expected unit type `()`
                    found enum `Result<(), _>`
 
-error: aborting due to previous error; 1 warning emitted
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/async-await/in-trait/return-type-suggestion.next.stderr b/tests/ui/async-await/in-trait/return-type-suggestion.next.stderr
index a5efc757156..6a107d7beb8 100644
--- a/tests/ui/async-await/in-trait/return-type-suggestion.next.stderr
+++ b/tests/ui/async-await/in-trait/return-type-suggestion.next.stderr
@@ -1,14 +1,5 @@
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/return-type-suggestion.rs:5:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0308]: mismatched types
-  --> $DIR/return-type-suggestion.rs:10:9
+  --> $DIR/return-type-suggestion.rs:9:9
    |
 LL |         Ok(())
    |         ^^^^^^- help: consider using a semicolon here: `;`
@@ -18,6 +9,6 @@ LL |         Ok(())
    = note: expected unit type `()`
                    found enum `Result<(), _>`
 
-error: aborting due to previous error; 1 warning emitted
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/async-await/in-trait/return-type-suggestion.rs b/tests/ui/async-await/in-trait/return-type-suggestion.rs
index 3de66306d9a..d63bccefa9f 100644
--- a/tests/ui/async-await/in-trait/return-type-suggestion.rs
+++ b/tests/ui/async-await/in-trait/return-type-suggestion.rs
@@ -3,7 +3,6 @@
 // revisions: current next
 
 #![feature(async_fn_in_trait)]
-//~^ WARN the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
 
 trait A {
     async fn e() {
diff --git a/tests/ui/async-await/return-type-notation/issue-110963-early.stderr b/tests/ui/async-await/return-type-notation/issue-110963-early.stderr
index b4a3924d8da..33e22dec3f7 100644
--- a/tests/ui/async-await/return-type-notation/issue-110963-early.stderr
+++ b/tests/ui/async-await/return-type-notation/issue-110963-early.stderr
@@ -7,14 +7,6 @@ LL | #![feature(return_type_notation)]
    = note: see issue #109417 <https://github.com/rust-lang/rust/issues/109417> for more information
    = note: `#[warn(incomplete_features)]` on by default
 
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/issue-110963-early.rs:5:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-
 error: higher-ranked lifetime error
   --> $DIR/issue-110963-early.rs:15:5
    |
@@ -41,5 +33,5 @@ LL | |     });
    |
    = note: could not prove `[async block@$DIR/issue-110963-early.rs:15:11: 20:6]: Send`
 
-error: aborting due to 2 previous errors; 2 warnings emitted
+error: aborting due to 2 previous errors; 1 warning emitted
 
diff --git a/tests/ui/async-await/return-type-notation/issue-110963-late.rs b/tests/ui/async-await/return-type-notation/issue-110963-late.rs
index 2a35922eaa1..17b5d775d44 100644
--- a/tests/ui/async-await/return-type-notation/issue-110963-late.rs
+++ b/tests/ui/async-await/return-type-notation/issue-110963-late.rs
@@ -4,7 +4,6 @@
 #![feature(return_type_notation)]
 //~^ WARN the feature `return_type_notation` is incomplete
 #![feature(async_fn_in_trait)]
-//~^ WARN the feature `async_fn_in_trait` is incomplete
 
 trait HealthCheck {
     async fn check(&mut self) -> bool;
diff --git a/tests/ui/async-await/return-type-notation/issue-110963-late.stderr b/tests/ui/async-await/return-type-notation/issue-110963-late.stderr
index 36ef3ad0a4c..9c6966537a7 100644
--- a/tests/ui/async-await/return-type-notation/issue-110963-late.stderr
+++ b/tests/ui/async-await/return-type-notation/issue-110963-late.stderr
@@ -7,13 +7,5 @@ LL | #![feature(return_type_notation)]
    = note: see issue #109417 <https://github.com/rust-lang/rust/issues/109417> for more information
    = note: `#[warn(incomplete_features)]` on by default
 
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/issue-110963-late.rs:6:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-
-warning: 2 warnings emitted
+warning: 1 warning emitted
 
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_bad.rs b/tests/ui/const-generics/adt_const_params/const_param_ty_bad.rs
new file mode 100644
index 00000000000..0da68ae7573
--- /dev/null
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_bad.rs
@@ -0,0 +1,13 @@
+#![allow(incomplete_features)]
+#![feature(adt_const_params)]
+
+fn check(_: impl std::marker::ConstParamTy) {}
+
+fn main() {
+    check(main);               //~ error: `fn() {main}` can't be used as a const parameter type
+    check(|| {});              //~ error: `[closure@$DIR/const_param_ty_bad.rs:8:11: 8:13]` can't be used as a const parameter type
+    check(main as fn());       //~ error: `fn()` can't be used as a const parameter type
+    check(&mut ());            //~ error: `&mut ()` can't be used as a const parameter type
+    check(&mut () as *mut ()); //~ error: `*mut ()` can't be used as a const parameter type
+    check(&() as *const ());   //~ error: `*const ()` can't be used as a const parameter type
+}
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_bad.stderr b/tests/ui/const-generics/adt_const_params/const_param_ty_bad.stderr
new file mode 100644
index 00000000000..de5704ee429
--- /dev/null
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_bad.stderr
@@ -0,0 +1,87 @@
+error[E0277]: `fn() {main}` can't be used as a const parameter type
+  --> $DIR/const_param_ty_bad.rs:7:11
+   |
+LL |     check(main);
+   |     ----- ^^^^ the trait `ConstParamTy` is not implemented for fn item `fn() {main}`
+   |     |
+   |     required by a bound introduced by this call
+   |
+note: required by a bound in `check`
+  --> $DIR/const_param_ty_bad.rs:4:18
+   |
+LL | fn check(_: impl std::marker::ConstParamTy) {}
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+
+error[E0277]: `[closure@$DIR/const_param_ty_bad.rs:8:11: 8:13]` can't be used as a const parameter type
+  --> $DIR/const_param_ty_bad.rs:8:11
+   |
+LL |     check(|| {});
+   |     ----- ^^^^^ the trait `ConstParamTy` is not implemented for closure `[closure@$DIR/const_param_ty_bad.rs:8:11: 8:13]`
+   |     |
+   |     required by a bound introduced by this call
+   |
+note: required by a bound in `check`
+  --> $DIR/const_param_ty_bad.rs:4:18
+   |
+LL | fn check(_: impl std::marker::ConstParamTy) {}
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+
+error[E0277]: `fn()` can't be used as a const parameter type
+  --> $DIR/const_param_ty_bad.rs:9:11
+   |
+LL |     check(main as fn());
+   |     ----- ^^^^^^^^^^^^ the trait `ConstParamTy` is not implemented for `fn()`
+   |     |
+   |     required by a bound introduced by this call
+   |
+note: required by a bound in `check`
+  --> $DIR/const_param_ty_bad.rs:4:18
+   |
+LL | fn check(_: impl std::marker::ConstParamTy) {}
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+
+error[E0277]: `&mut ()` can't be used as a const parameter type
+  --> $DIR/const_param_ty_bad.rs:10:11
+   |
+LL |     check(&mut ());
+   |     ----- ^^^^^^^ the trait `ConstParamTy` is not implemented for `&mut ()`
+   |     |
+   |     required by a bound introduced by this call
+   |
+note: required by a bound in `check`
+  --> $DIR/const_param_ty_bad.rs:4:18
+   |
+LL | fn check(_: impl std::marker::ConstParamTy) {}
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+
+error[E0277]: `*mut ()` can't be used as a const parameter type
+  --> $DIR/const_param_ty_bad.rs:11:11
+   |
+LL |     check(&mut () as *mut ());
+   |     ----- ^^^^^^^^^^^^^^^^^^ the trait `ConstParamTy` is not implemented for `*mut ()`
+   |     |
+   |     required by a bound introduced by this call
+   |
+note: required by a bound in `check`
+  --> $DIR/const_param_ty_bad.rs:4:18
+   |
+LL | fn check(_: impl std::marker::ConstParamTy) {}
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+
+error[E0277]: `*const ()` can't be used as a const parameter type
+  --> $DIR/const_param_ty_bad.rs:12:11
+   |
+LL |     check(&() as *const ());
+   |     ----- ^^^^^^^^^^^^^^^^ the trait `ConstParamTy` is not implemented for `*const ()`
+   |     |
+   |     required by a bound introduced by this call
+   |
+note: required by a bound in `check`
+  --> $DIR/const_param_ty_bad.rs:4:18
+   |
+LL | fn check(_: impl std::marker::ConstParamTy) {}
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+
+error: aborting due to 6 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_bad_empty_array.rs b/tests/ui/const-generics/adt_const_params/const_param_ty_bad_empty_array.rs
new file mode 100644
index 00000000000..b0e3b13cc1e
--- /dev/null
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_bad_empty_array.rs
@@ -0,0 +1,12 @@
+#![allow(incomplete_features)]
+#![feature(adt_const_params)]
+
+#[derive(PartialEq, Eq)]
+struct NotParam;
+
+fn check<T: std::marker::ConstParamTy>() {}
+
+fn main() {
+    check::<[NotParam; 0]>();
+    //~^ error: `NotParam` can't be used as a const parameter type
+}
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_bad_empty_array.stderr b/tests/ui/const-generics/adt_const_params/const_param_ty_bad_empty_array.stderr
new file mode 100644
index 00000000000..ef55242df87
--- /dev/null
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_bad_empty_array.stderr
@@ -0,0 +1,16 @@
+error[E0277]: `NotParam` can't be used as a const parameter type
+  --> $DIR/const_param_ty_bad_empty_array.rs:10:13
+   |
+LL |     check::<[NotParam; 0]>();
+   |             ^^^^^^^^^^^^^ the trait `ConstParamTy` is not implemented for `NotParam`
+   |
+   = note: required for `[NotParam; 0]` to implement `ConstParamTy`
+note: required by a bound in `check`
+  --> $DIR/const_param_ty_bad_empty_array.rs:7:13
+   |
+LL | fn check<T: std::marker::ConstParamTy>() {}
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_generic_bounds_do_not_hold.rs b/tests/ui/const-generics/adt_const_params/const_param_ty_generic_bounds_do_not_hold.rs
new file mode 100644
index 00000000000..e4dc76703a2
--- /dev/null
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_generic_bounds_do_not_hold.rs
@@ -0,0 +1,13 @@
+#![allow(incomplete_features)]
+#![feature(adt_const_params)]
+
+#[derive(PartialEq, Eq)]
+struct NotParam;
+
+fn check<T: std::marker::ConstParamTy + ?Sized>() {}
+
+fn main() {
+    check::<&NotParam>();      //~ error: `NotParam` can't be used as a const parameter type
+    check::<[NotParam]>();     //~ error: `NotParam` can't be used as a const parameter type
+    check::<[NotParam; 17]>(); //~ error: `NotParam` can't be used as a const parameter type
+}
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_generic_bounds_do_not_hold.stderr b/tests/ui/const-generics/adt_const_params/const_param_ty_generic_bounds_do_not_hold.stderr
new file mode 100644
index 00000000000..86d1c94e87f
--- /dev/null
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_generic_bounds_do_not_hold.stderr
@@ -0,0 +1,42 @@
+error[E0277]: `NotParam` can't be used as a const parameter type
+  --> $DIR/const_param_ty_generic_bounds_do_not_hold.rs:10:13
+   |
+LL |     check::<&NotParam>();
+   |             ^^^^^^^^^ the trait `ConstParamTy` is not implemented for `NotParam`
+   |
+   = note: required for `&NotParam` to implement `ConstParamTy`
+note: required by a bound in `check`
+  --> $DIR/const_param_ty_generic_bounds_do_not_hold.rs:7:13
+   |
+LL | fn check<T: std::marker::ConstParamTy + ?Sized>() {}
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+
+error[E0277]: `NotParam` can't be used as a const parameter type
+  --> $DIR/const_param_ty_generic_bounds_do_not_hold.rs:11:13
+   |
+LL |     check::<[NotParam]>();
+   |             ^^^^^^^^^^ the trait `ConstParamTy` is not implemented for `NotParam`
+   |
+   = note: required for `[NotParam]` to implement `ConstParamTy`
+note: required by a bound in `check`
+  --> $DIR/const_param_ty_generic_bounds_do_not_hold.rs:7:13
+   |
+LL | fn check<T: std::marker::ConstParamTy + ?Sized>() {}
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+
+error[E0277]: `NotParam` can't be used as a const parameter type
+  --> $DIR/const_param_ty_generic_bounds_do_not_hold.rs:12:13
+   |
+LL |     check::<[NotParam; 17]>();
+   |             ^^^^^^^^^^^^^^ the trait `ConstParamTy` is not implemented for `NotParam`
+   |
+   = note: required for `[NotParam; 17]` to implement `ConstParamTy`
+note: required by a bound in `check`
+  --> $DIR/const_param_ty_generic_bounds_do_not_hold.rs:7:13
+   |
+LL | fn check<T: std::marker::ConstParamTy + ?Sized>() {}
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_good.rs b/tests/ui/const-generics/adt_const_params/const_param_ty_good.rs
new file mode 100644
index 00000000000..a1b711a3024
--- /dev/null
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_good.rs
@@ -0,0 +1,43 @@
+// check-pass
+#![allow(incomplete_features)]
+#![feature(adt_const_params)]
+use std::marker::ConstParamTy;
+
+#[derive(PartialEq, Eq)]
+struct S<T> {
+    field: u8,
+    gen: T,
+}
+
+impl<T: ConstParamTy> ConstParamTy for S<T> {}
+
+fn check<T: ConstParamTy + ?Sized>() {}
+
+fn main() {
+    check::<u8>();
+    check::<u16>();
+    check::<u32>();
+    check::<u64>();
+    check::<u128>();
+
+    check::<i8>();
+    check::<i16>();
+    check::<i32>();
+    check::<i64>();
+    check::<i128>();
+
+    check::<char>();
+    check::<bool>();
+    check::<str>();
+
+    check::<&u8>();
+    check::<&str>();
+    check::<[usize]>();
+    check::<[u16; 0]>();
+    check::<[u8; 42]>();
+
+    check::<S<u8>>();
+    check::<S<[&[bool]; 8]>>();
+
+    // FIXME: test tuples
+}
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_bad_field.rs b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_bad_field.rs
new file mode 100644
index 00000000000..07fd243737e
--- /dev/null
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_bad_field.rs
@@ -0,0 +1,13 @@
+#![allow(incomplete_features)]
+#![feature(adt_const_params)]
+
+#[derive(PartialEq, Eq)]
+struct NotParam;
+
+#[derive(PartialEq, Eq)]
+struct CantParam(NotParam);
+
+impl std::marker::ConstParamTy for CantParam {}
+//~^ error: the trait `ConstParamTy` cannot be implemented for this type
+
+fn main() {}
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_bad_field.stderr b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_bad_field.stderr
new file mode 100644
index 00000000000..c8e065848b1
--- /dev/null
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_bad_field.stderr
@@ -0,0 +1,12 @@
+error[E0204]: the trait `ConstParamTy` cannot be implemented for this type
+  --> $DIR/const_param_ty_impl_bad_field.rs:10:36
+   |
+LL | struct CantParam(NotParam);
+   |                  -------- this field does not implement `ConstParamTy`
+LL |
+LL | impl std::marker::ConstParamTy for CantParam {}
+   |                                    ^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0204`.
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_no_structural_eq.rs b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_no_structural_eq.rs
new file mode 100644
index 00000000000..17ef396164e
--- /dev/null
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_no_structural_eq.rs
@@ -0,0 +1,17 @@
+#![allow(incomplete_features)]
+#![feature(adt_const_params)]
+
+#[derive(PartialEq, Eq)]
+struct ImplementsConstParamTy;
+impl std::marker::ConstParamTy for ImplementsConstParamTy {}
+
+struct CantParam(ImplementsConstParamTy);
+
+impl std::marker::ConstParamTy for CantParam {}
+//~^ error: the type `CantParam` does not `#[derive(Eq)]`
+
+fn check<T: std::marker::ConstParamTy>() {}
+
+fn main() {
+    check::<ImplementsConstParamTy>();
+}
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_no_structural_eq.stderr b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_no_structural_eq.stderr
new file mode 100644
index 00000000000..ca5abf5e254
--- /dev/null
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_no_structural_eq.stderr
@@ -0,0 +1,12 @@
+error[E0277]: the type `CantParam` does not `#[derive(Eq)]`
+  --> $DIR/const_param_ty_impl_no_structural_eq.rs:10:36
+   |
+LL | impl std::marker::ConstParamTy for CantParam {}
+   |                                    ^^^^^^^^^ the trait `StructuralEq` is not implemented for `CantParam`
+   |
+note: required by a bound in `ConstParamTy`
+  --> $SRC_DIR/core/src/marker.rs:LL:COL
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/const-generics/assoc_const_eq_diagnostic.rs b/tests/ui/const-generics/assoc_const_eq_diagnostic.rs
index 4d0aaf88e40..bf8202ac152 100644
--- a/tests/ui/const-generics/assoc_const_eq_diagnostic.rs
+++ b/tests/ui/const-generics/assoc_const_eq_diagnostic.rs
@@ -10,6 +10,7 @@ pub trait Parse {
 
 pub trait CoolStuff: Parse<MODE = Mode::Cool> {}
 //~^ ERROR expected associated constant bound
+//~| ERROR expected associated constant bound
 //~| ERROR expected type
 
 fn no_help() -> Mode::Cool {}
diff --git a/tests/ui/const-generics/assoc_const_eq_diagnostic.stderr b/tests/ui/const-generics/assoc_const_eq_diagnostic.stderr
index ba727ee0ea3..d7e5e50cba8 100644
--- a/tests/ui/const-generics/assoc_const_eq_diagnostic.stderr
+++ b/tests/ui/const-generics/assoc_const_eq_diagnostic.stderr
@@ -8,7 +8,7 @@ LL | pub trait CoolStuff: Parse<MODE = Mode::Cool> {}
    |                                   help: try using the variant's enum: `Mode`
 
 error[E0573]: expected type, found variant `Mode::Cool`
-  --> $DIR/assoc_const_eq_diagnostic.rs:15:17
+  --> $DIR/assoc_const_eq_diagnostic.rs:16:17
    |
 LL | fn no_help() -> Mode::Cool {}
    |                 ^^^^^^^^^^
@@ -28,6 +28,18 @@ note: associated constant defined here
 LL |     const MODE: Mode;
    |     ^^^^^^^^^^^^^^^^
 
-error: aborting due to 3 previous errors
+error: expected associated constant bound, found type
+  --> $DIR/assoc_const_eq_diagnostic.rs:11:28
+   |
+LL | pub trait CoolStuff: Parse<MODE = Mode::Cool> {}
+   |                            ^^^^^^^^^^^^^^^^^ help: if equating a const, try wrapping with braces: `MODE = { const }`
+   |
+note: associated constant defined here
+  --> $DIR/assoc_const_eq_diagnostic.rs:8:5
+   |
+LL |     const MODE: Mode;
+   |     ^^^^^^^^^^^^^^^^
+
+error: aborting due to 4 previous errors
 
 For more information about this error, try `rustc --explain E0573`.
diff --git a/tests/ui/const-generics/nested-type.rs b/tests/ui/const-generics/nested-type.rs
index 5240f5c3b0b..ff95018065a 100644
--- a/tests/ui/const-generics/nested-type.rs
+++ b/tests/ui/const-generics/nested-type.rs
@@ -3,7 +3,7 @@
 #![cfg_attr(full, feature(adt_const_params))]
 #![cfg_attr(full, allow(incomplete_features))]
 
-struct Foo<const N: [u8; { //[min]~ ERROR `[u8; _]` is forbidden
+struct Foo<const N: [u8; {
     struct Foo<const N: usize>;
 
     impl<const N: usize> Foo<N> {
@@ -15,5 +15,9 @@ struct Foo<const N: [u8; { //[min]~ ERROR `[u8; _]` is forbidden
     Foo::<17>::value()
     //~^ ERROR cannot call non-const fn
 }]>;
+//[min]~^^^^^^^^^^^^ ERROR `[u8; {
+
+// N.B. it is important that the comment above is not inside the array length,
+//      otherwise it may check for itself, instead of the actual error
 
 fn main() {}
diff --git a/tests/ui/error-codes/E0719.rs b/tests/ui/error-codes/E0719.rs
index 3311e190937..cbf1bb219a0 100644
--- a/tests/ui/error-codes/E0719.rs
+++ b/tests/ui/error-codes/E0719.rs
@@ -1,5 +1,6 @@
 trait Foo: Iterator<Item = i32, Item = i32> {}
 //~^ ERROR is already specified
+//~| ERROR is already specified
 
 type Unit = ();
 
diff --git a/tests/ui/error-codes/E0719.stderr b/tests/ui/error-codes/E0719.stderr
index b342d634334..e302f406d02 100644
--- a/tests/ui/error-codes/E0719.stderr
+++ b/tests/ui/error-codes/E0719.stderr
@@ -7,13 +7,21 @@ LL | trait Foo: Iterator<Item = i32, Item = i32> {}
    |                     `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
-  --> $DIR/E0719.rs:6:42
+  --> $DIR/E0719.rs:1:33
+   |
+LL | trait Foo: Iterator<Item = i32, Item = i32> {}
+   |                     ----------  ^^^^^^^^^^ re-bound here
+   |                     |
+   |                     `Item` bound here first
+
+error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
+  --> $DIR/E0719.rs:7:42
    |
 LL | fn test() -> Box<dyn Iterator<Item = (), Item = Unit>> {
    |                               ---------  ^^^^^^^^^^^ re-bound here
    |                               |
    |                               `Item` bound here first
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors
 
 For more information about this error, try `rustc --explain E0719`.
diff --git a/tests/ui/feature-gates/feature-gate-debugger-visualizer.rs b/tests/ui/feature-gates/feature-gate-debugger-visualizer.rs
deleted file mode 100644
index 4c4dc450d18..00000000000
--- a/tests/ui/feature-gates/feature-gate-debugger-visualizer.rs
+++ /dev/null
@@ -1,3 +0,0 @@
-#![debugger_visualizer(natvis_file = "auxiliary/debugger-visualizer.natvis")] //~ ERROR the `#[debugger_visualizer]` attribute is an experimental feature
-
-fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-debugger-visualizer.stderr b/tests/ui/feature-gates/feature-gate-debugger-visualizer.stderr
deleted file mode 100644
index e9367fbc6c9..00000000000
--- a/tests/ui/feature-gates/feature-gate-debugger-visualizer.stderr
+++ /dev/null
@@ -1,12 +0,0 @@
-error[E0658]: the `#[debugger_visualizer]` attribute is an experimental feature
-  --> $DIR/feature-gate-debugger-visualizer.rs:1:1
-   |
-LL | #![debugger_visualizer(natvis_file = "auxiliary/debugger-visualizer.natvis")]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #95939 <https://github.com/rust-lang/rust/issues/95939> for more information
-   = help: add `#![feature(debugger_visualizer)]` to the crate attributes to enable
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-return_type_notation.cfg.stderr b/tests/ui/feature-gates/feature-gate-return_type_notation.cfg.stderr
index c3a371e25e8..1bdb2574ead 100644
--- a/tests/ui/feature-gates/feature-gate-return_type_notation.cfg.stderr
+++ b/tests/ui/feature-gates/feature-gate-return_type_notation.cfg.stderr
@@ -1,5 +1,5 @@
 error[E0658]: return type notation is experimental
-  --> $DIR/feature-gate-return_type_notation.rs:15:17
+  --> $DIR/feature-gate-return_type_notation.rs:14:17
    |
 LL | fn foo<T: Trait<m(): Send>>() {}
    |                 ^^^^^^^^^
@@ -7,17 +7,8 @@ LL | fn foo<T: Trait<m(): Send>>() {}
    = note: see issue #109417 <https://github.com/rust-lang/rust/issues/109417> for more information
    = help: add `#![feature(return_type_notation)]` to the crate attributes to enable
 
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/feature-gate-return_type_notation.rs:7:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 error: parenthesized generic arguments cannot be used in associated type constraints
-  --> $DIR/feature-gate-return_type_notation.rs:15:17
+  --> $DIR/feature-gate-return_type_notation.rs:14:17
    |
 LL | fn foo<T: Trait<m(): Send>>() {}
    |                 ^--
@@ -25,12 +16,12 @@ LL | fn foo<T: Trait<m(): Send>>() {}
    |                  help: remove these parentheses
 
 error[E0220]: associated type `m` not found for `Trait`
-  --> $DIR/feature-gate-return_type_notation.rs:15:17
+  --> $DIR/feature-gate-return_type_notation.rs:14:17
    |
 LL | fn foo<T: Trait<m(): Send>>() {}
    |                 ^ associated type `m` not found
 
-error: aborting due to 3 previous errors; 1 warning emitted
+error: aborting due to 3 previous errors
 
 Some errors have detailed explanations: E0220, E0658.
 For more information about an error, try `rustc --explain E0220`.
diff --git a/tests/ui/feature-gates/feature-gate-return_type_notation.no.stderr b/tests/ui/feature-gates/feature-gate-return_type_notation.no.stderr
index 52c90c1565c..dd6ebb61038 100644
--- a/tests/ui/feature-gates/feature-gate-return_type_notation.no.stderr
+++ b/tests/ui/feature-gates/feature-gate-return_type_notation.no.stderr
@@ -1,14 +1,5 @@
-warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/feature-gate-return_type_notation.rs:7:12
-   |
-LL | #![feature(async_fn_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 warning: return type notation is experimental
-  --> $DIR/feature-gate-return_type_notation.rs:15:17
+  --> $DIR/feature-gate-return_type_notation.rs:14:17
    |
 LL | fn foo<T: Trait<m(): Send>>() {}
    |                 ^^^^^^^^^
@@ -18,5 +9,5 @@ LL | fn foo<T: Trait<m(): Send>>() {}
    = warning: unstable syntax can change at any point in the future, causing a hard error!
    = note: for more information, see issue #65860 <https://github.com/rust-lang/rust/issues/65860>
 
-warning: 2 warnings emitted
+warning: 1 warning emitted
 
diff --git a/tests/ui/feature-gates/feature-gate-return_type_notation.rs b/tests/ui/feature-gates/feature-gate-return_type_notation.rs
index 5028b9ec9e3..d9bcb65feba 100644
--- a/tests/ui/feature-gates/feature-gate-return_type_notation.rs
+++ b/tests/ui/feature-gates/feature-gate-return_type_notation.rs
@@ -5,7 +5,6 @@
 // Since we're not adding new syntax, `cfg`'d out RTN must pass.
 
 #![feature(async_fn_in_trait)]
-//~^ WARN the feature `async_fn_in_trait` is incomplete
 
 trait Trait {
     async fn m();
diff --git a/tests/ui/fmt/format-string-error.rs b/tests/ui/fmt/format-string-error.rs
index eae4f3cb547..9b436e2c479 100644
--- a/tests/ui/fmt/format-string-error.rs
+++ b/tests/ui/fmt/format-string-error.rs
@@ -17,7 +17,7 @@ fn main() {
     let _ = format!("}");
     //~^ ERROR invalid format string: unmatched `}` found
     let _ = format!("{\\}");
-    //~^ ERROR invalid format string: expected `'}'`, found `'\\'`
+    //~^ ERROR invalid format string: expected `'}'`, found `'\'`
     let _ = format!("\n\n\n{\n\n\n");
     //~^ ERROR invalid format string
     let _ = format!(r###"
diff --git a/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.current.stderr b/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.current.stderr
deleted file mode 100644
index 05c025cc169..00000000000
--- a/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.current.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/box-coerce-span-in-default.rs:5:12
-   |
-LL | #![feature(return_position_impl_trait_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-warning: 1 warning emitted
-
diff --git a/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.next.stderr b/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.next.stderr
deleted file mode 100644
index 05c025cc169..00000000000
--- a/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.next.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/box-coerce-span-in-default.rs:5:12
-   |
-LL | #![feature(return_position_impl_trait_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-warning: 1 warning emitted
-
diff --git a/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.rs b/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.rs
index 163bb4fcf77..f5290a5f4af 100644
--- a/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.rs
+++ b/tests/ui/impl-trait/in-trait/box-coerce-span-in-default.rs
@@ -3,7 +3,6 @@
 // revisions: current next
 
 #![feature(return_position_impl_trait_in_trait)]
-//~^ WARN the feature `return_position_impl_trait_in_trait` is incomplete
 
 struct TestA {}
 struct TestB {}
diff --git a/tests/ui/impl-trait/in-trait/default-method-binder-shifting.current.stderr b/tests/ui/impl-trait/in-trait/default-method-binder-shifting.current.stderr
deleted file mode 100644
index a0c0589b9a1..00000000000
--- a/tests/ui/impl-trait/in-trait/default-method-binder-shifting.current.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/default-method-binder-shifting.rs:5:12
-   |
-LL | #![feature(return_position_impl_trait_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-warning: 1 warning emitted
-
diff --git a/tests/ui/impl-trait/in-trait/default-method-binder-shifting.next.stderr b/tests/ui/impl-trait/in-trait/default-method-binder-shifting.next.stderr
deleted file mode 100644
index a0c0589b9a1..00000000000
--- a/tests/ui/impl-trait/in-trait/default-method-binder-shifting.next.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/default-method-binder-shifting.rs:5:12
-   |
-LL | #![feature(return_position_impl_trait_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-warning: 1 warning emitted
-
diff --git a/tests/ui/impl-trait/in-trait/default-method-binder-shifting.rs b/tests/ui/impl-trait/in-trait/default-method-binder-shifting.rs
index de82544f293..187039f449c 100644
--- a/tests/ui/impl-trait/in-trait/default-method-binder-shifting.rs
+++ b/tests/ui/impl-trait/in-trait/default-method-binder-shifting.rs
@@ -3,7 +3,6 @@
 // revisions: current next
 
 #![feature(return_position_impl_trait_in_trait)]
-//~^ WARN the feature `return_position_impl_trait_in_trait` is incomplete
 
 trait Trait {
     type Type;
diff --git a/tests/ui/impl-trait/in-trait/default-method-constraint.current.stderr b/tests/ui/impl-trait/in-trait/default-method-constraint.current.stderr
deleted file mode 100644
index 7bb79911f56..00000000000
--- a/tests/ui/impl-trait/in-trait/default-method-constraint.current.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/default-method-constraint.rs:7:12
-   |
-LL | #![feature(return_position_impl_trait_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-warning: 1 warning emitted
-
diff --git a/tests/ui/impl-trait/in-trait/default-method-constraint.next.stderr b/tests/ui/impl-trait/in-trait/default-method-constraint.next.stderr
deleted file mode 100644
index 7bb79911f56..00000000000
--- a/tests/ui/impl-trait/in-trait/default-method-constraint.next.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/default-method-constraint.rs:7:12
-   |
-LL | #![feature(return_position_impl_trait_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-warning: 1 warning emitted
-
diff --git a/tests/ui/impl-trait/in-trait/default-method-constraint.rs b/tests/ui/impl-trait/in-trait/default-method-constraint.rs
index e85fe3c8626..4f0bf2e7dfe 100644
--- a/tests/ui/impl-trait/in-trait/default-method-constraint.rs
+++ b/tests/ui/impl-trait/in-trait/default-method-constraint.rs
@@ -5,7 +5,6 @@
 // This didn't work in the previous default RPITIT method hack attempt
 
 #![feature(return_position_impl_trait_in_trait)]
-//~^ WARN the feature `return_position_impl_trait_in_trait` is incomplete
 
 trait Foo {
     fn bar(x: bool) -> impl Sized {
diff --git a/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.current.stderr b/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.current.stderr
index b8a793e1a7b..d4d0124a659 100644
--- a/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.current.stderr
+++ b/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.current.stderr
@@ -1,14 +1,5 @@
-warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/dont-project-to-rpitit-with-no-value.rs:4:12
-   |
-LL | #![feature(return_position_impl_trait_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0046]: not all trait items implemented, missing: `foo`
-  --> $DIR/dont-project-to-rpitit-with-no-value.rs:12:1
+  --> $DIR/dont-project-to-rpitit-with-no-value.rs:11:1
    |
 LL |     fn foo(&self) -> impl Sized;
    |     ---------------------------- `foo` from trait
@@ -16,6 +7,6 @@ LL |     fn foo(&self) -> impl Sized;
 LL | impl MyTrait for i32 {
    | ^^^^^^^^^^^^^^^^^^^^ missing `foo` in implementation
 
-error: aborting due to previous error; 1 warning emitted
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0046`.
diff --git a/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.next.stderr b/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.next.stderr
index b8a793e1a7b..d4d0124a659 100644
--- a/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.next.stderr
+++ b/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.next.stderr
@@ -1,14 +1,5 @@
-warning: the feature `return_position_impl_trait_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/dont-project-to-rpitit-with-no-value.rs:4:12
-   |
-LL | #![feature(return_position_impl_trait_in_trait)]
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0046]: not all trait items implemented, missing: `foo`
-  --> $DIR/dont-project-to-rpitit-with-no-value.rs:12:1
+  --> $DIR/dont-project-to-rpitit-with-no-value.rs:11:1
    |
 LL |     fn foo(&self) -> impl Sized;
    |     ---------------------------- `foo` from trait
@@ -16,6 +7,6 @@ LL |     fn foo(&self) -> impl Sized;
 LL | impl MyTrait for i32 {
    | ^^^^^^^^^^^^^^^^^^^^ missing `foo` in implementation
 
-error: aborting due to previous error; 1 warning emitted
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0046`.
diff --git a/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.rs b/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.rs
index 8329ce1f835..4d50b8c9278 100644
--- a/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.rs
+++ b/tests/ui/impl-trait/in-trait/dont-project-to-rpitit-with-no-value.rs
@@ -2,7 +2,6 @@
 // revisions: current next
 
 #![feature(return_position_impl_trait_in_trait)]
-//~^ WARN the feature `return_position_impl_trait_in_trait` is incomplete
 
 trait MyTrait {
     fn foo(&self) -> impl Sized;
diff --git a/tests/ui/invalid/invalid-debugger-visualizer-option.rs b/tests/ui/invalid/invalid-debugger-visualizer-option.rs
index 5645a30ccee..150723898bd 100644
--- a/tests/ui/invalid/invalid-debugger-visualizer-option.rs
+++ b/tests/ui/invalid/invalid-debugger-visualizer-option.rs
@@ -1,7 +1,6 @@
 // normalize-stderr-test: "foo.random:.*\(" -> "foo.random: $$FILE_NOT_FOUND_MSG ("
 // normalize-stderr-test: "os error \d+" -> "os error $$FILE_NOT_FOUND_CODE"
 
-#![feature(debugger_visualizer)]
 #![debugger_visualizer(random_file = "../foo.random")] //~ ERROR invalid argument
 #![debugger_visualizer(natvis_file = "../foo.random")] //~ ERROR
 fn main() {}
diff --git a/tests/ui/invalid/invalid-debugger-visualizer-option.stderr b/tests/ui/invalid/invalid-debugger-visualizer-option.stderr
index afb8d16ee96..6fbb4d641e6 100644
--- a/tests/ui/invalid/invalid-debugger-visualizer-option.stderr
+++ b/tests/ui/invalid/invalid-debugger-visualizer-option.stderr
@@ -1,5 +1,5 @@
 error: invalid argument
-  --> $DIR/invalid-debugger-visualizer-option.rs:5:24
+  --> $DIR/invalid-debugger-visualizer-option.rs:4:24
    |
 LL | #![debugger_visualizer(random_file = "../foo.random")]
    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -9,7 +9,7 @@ LL | #![debugger_visualizer(random_file = "../foo.random")]
    = note: expected: `gdb_script_file = "..."`
 
 error: couldn't read $DIR/../foo.random: $FILE_NOT_FOUND_MSG (os error $FILE_NOT_FOUND_CODE)
-  --> $DIR/invalid-debugger-visualizer-option.rs:6:24
+  --> $DIR/invalid-debugger-visualizer-option.rs:5:24
    |
 LL | #![debugger_visualizer(natvis_file = "../foo.random")]
    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/invalid/invalid-debugger-visualizer-target.rs b/tests/ui/invalid/invalid-debugger-visualizer-target.rs
index f0aba6a75c4..f9dd20dbfed 100644
--- a/tests/ui/invalid/invalid-debugger-visualizer-target.rs
+++ b/tests/ui/invalid/invalid-debugger-visualizer-target.rs
@@ -1,4 +1,2 @@
-#![feature(debugger_visualizer)]
-
 #[debugger_visualizer(natvis_file = "../foo.natvis")] //~ ERROR attribute should be applied to a module
 fn main() {}
diff --git a/tests/ui/invalid/invalid-debugger-visualizer-target.stderr b/tests/ui/invalid/invalid-debugger-visualizer-target.stderr
index 3555bbb169b..7944f751859 100644
--- a/tests/ui/invalid/invalid-debugger-visualizer-target.stderr
+++ b/tests/ui/invalid/invalid-debugger-visualizer-target.stderr
@@ -1,5 +1,5 @@
 error: attribute should be applied to a module
-  --> $DIR/invalid-debugger-visualizer-target.rs:3:1
+  --> $DIR/invalid-debugger-visualizer-target.rs:1:1
    |
 LL | #[debugger_visualizer(natvis_file = "../foo.natvis")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/lint/noop-method-call.rs b/tests/ui/lint/noop-method-call.rs
index 89b29663595..dbcf2a5131b 100644
--- a/tests/ui/lint/noop-method-call.rs
+++ b/tests/ui/lint/noop-method-call.rs
@@ -19,18 +19,17 @@ fn main() {
     let clone_type_ref = &CloneType(1u32);
     let clone_type_ref_clone: CloneType<u32> = clone_type_ref.clone();
 
-    // Calling clone on a double reference doesn't warn since the method call itself
-    // peels the outer reference off
     let clone_type_ref = &&CloneType(1u32);
     let clone_type_ref_clone: &CloneType<u32> = clone_type_ref.clone();
+    //~^ WARNING using `.clone()` on a double reference, which returns `&CloneType<u32>`
 
     let non_deref_type = &PlainType(1u32);
     let non_deref_type_deref: &PlainType<u32> = non_deref_type.deref();
     //~^ WARNING call to `.deref()` on a reference in this situation does nothing
 
-    // Dereferencing a &&T does not warn since it has collapsed the double reference
     let non_deref_type = &&PlainType(1u32);
     let non_deref_type_deref: &PlainType<u32> = non_deref_type.deref();
+    //~^ WARNING using `.deref()` on a double reference, which returns `&PlainType<u32>`
 
     let non_borrow_type = &PlainType(1u32);
     let non_borrow_type_borrow: &PlainType<u32> = non_borrow_type.borrow();
@@ -41,7 +40,8 @@ fn main() {
     let non_borrow_type_borrow: &PlainType<u32> = non_borrow_type.borrow();
 
     let xs = ["a", "b", "c"];
-    let _v: Vec<&str> = xs.iter().map(|x| x.clone()).collect(); // ok, but could use `*x` instead
+    let _v: Vec<&str> = xs.iter().map(|x| x.clone()).collect(); // could use `*x` instead
+    //~^ WARNING using `.clone()` on a double reference, which returns `&str`
 }
 
 fn generic<T>(non_clone_type: &PlainType<T>) {
diff --git a/tests/ui/lint/noop-method-call.stderr b/tests/ui/lint/noop-method-call.stderr
index 6a904d01abc..37cd1a0fc18 100644
--- a/tests/ui/lint/noop-method-call.stderr
+++ b/tests/ui/lint/noop-method-call.stderr
@@ -11,22 +11,42 @@ note: the lint level is defined here
 LL | #![warn(noop_method_call)]
    |         ^^^^^^^^^^^^^^^^
 
+warning: using `.clone()` on a double reference, which returns `&CloneType<u32>` instead of cloning the inner type
+  --> $DIR/noop-method-call.rs:23:63
+   |
+LL |     let clone_type_ref_clone: &CloneType<u32> = clone_type_ref.clone();
+   |                                                               ^^^^^^^^
+   |
+   = note: `#[warn(suspicious_double_ref_op)]` on by default
+
 warning: call to `.deref()` on a reference in this situation does nothing
-  --> $DIR/noop-method-call.rs:28:63
+  --> $DIR/noop-method-call.rs:27:63
    |
 LL |     let non_deref_type_deref: &PlainType<u32> = non_deref_type.deref();
    |                                                               ^^^^^^^^ unnecessary method call
    |
    = note: the type `&PlainType<u32>` which `deref` is being called on is the same as the type returned from `deref`, so the method call does not do anything and can be removed
 
+warning: using `.deref()` on a double reference, which returns `&PlainType<u32>` instead of dereferencing the inner type
+  --> $DIR/noop-method-call.rs:31:63
+   |
+LL |     let non_deref_type_deref: &PlainType<u32> = non_deref_type.deref();
+   |                                                               ^^^^^^^^
+
 warning: call to `.borrow()` on a reference in this situation does nothing
-  --> $DIR/noop-method-call.rs:36:66
+  --> $DIR/noop-method-call.rs:35:66
    |
 LL |     let non_borrow_type_borrow: &PlainType<u32> = non_borrow_type.borrow();
    |                                                                  ^^^^^^^^^ unnecessary method call
    |
    = note: the type `&PlainType<u32>` which `borrow` is being called on is the same as the type returned from `borrow`, so the method call does not do anything and can be removed
 
+warning: using `.clone()` on a double reference, which returns `&str` instead of cloning the inner type
+  --> $DIR/noop-method-call.rs:43:44
+   |
+LL |     let _v: Vec<&str> = xs.iter().map(|x| x.clone()).collect(); // could use `*x` instead
+   |                                            ^^^^^^^^
+
 warning: call to `.clone()` on a reference in this situation does nothing
   --> $DIR/noop-method-call.rs:48:19
    |
@@ -43,5 +63,5 @@ LL |     non_clone_type.clone();
    |
    = note: the type `&PlainType<u32>` which `clone` is being called on is the same as the type returned from `clone`, so the method call does not do anything and can be removed
 
-warning: 5 warnings emitted
+warning: 8 warnings emitted
 
diff --git a/tests/ui/lint/suspicious-double-ref-op.rs b/tests/ui/lint/suspicious-double-ref-op.rs
new file mode 100644
index 00000000000..b9bcd31c2a8
--- /dev/null
+++ b/tests/ui/lint/suspicious-double-ref-op.rs
@@ -0,0 +1,30 @@
+#![feature(lazy_cell)]
+#![deny(suspicious_double_ref_op, noop_method_call)]
+
+pub fn clone_on_double_ref() {
+    let x = vec![1];
+    let y = &&x;
+    let z: &Vec<_> = y.clone();
+    //~^ ERROR using `.clone()` on a double reference, which returns `&Vec<i32>`
+
+    println!("{:p} {:p}", *y, z);
+}
+
+use std::sync::LazyLock;
+
+pub static STRS: LazyLock<&str> = LazyLock::new(|| "First");
+
+// https://github.com/rust-lang/rust-clippy/issues/9272
+fn rust_clippy_issue_9272() {
+    let str = STRS.clone();
+    println!("{str}")
+}
+
+fn check(mut encoded: &[u8]) {
+    let _ = &mut encoded.clone();
+    //~^ ERROR call to `.clone()` on a reference in this situation does nothing
+    let _ = &encoded.clone();
+    //~^ ERROR call to `.clone()` on a reference in this situation does nothing
+}
+
+fn main() {}
diff --git a/tests/ui/lint/suspicious-double-ref-op.stderr b/tests/ui/lint/suspicious-double-ref-op.stderr
new file mode 100644
index 00000000000..d15487ca238
--- /dev/null
+++ b/tests/ui/lint/suspicious-double-ref-op.stderr
@@ -0,0 +1,35 @@
+error: using `.clone()` on a double reference, which returns `&Vec<i32>` instead of cloning the inner type
+  --> $DIR/suspicious-double-ref-op.rs:7:23
+   |
+LL |     let z: &Vec<_> = y.clone();
+   |                       ^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/suspicious-double-ref-op.rs:2:9
+   |
+LL | #![deny(suspicious_double_ref_op, noop_method_call)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: call to `.clone()` on a reference in this situation does nothing
+  --> $DIR/suspicious-double-ref-op.rs:24:25
+   |
+LL |     let _ = &mut encoded.clone();
+   |                         ^^^^^^^^ unnecessary method call
+   |
+   = note: the type `&[u8]` which `clone` is being called on is the same as the type returned from `clone`, so the method call does not do anything and can be removed
+note: the lint level is defined here
+  --> $DIR/suspicious-double-ref-op.rs:2:35
+   |
+LL | #![deny(suspicious_double_ref_op, noop_method_call)]
+   |                                   ^^^^^^^^^^^^^^^^
+
+error: call to `.clone()` on a reference in this situation does nothing
+  --> $DIR/suspicious-double-ref-op.rs:26:21
+   |
+LL |     let _ = &encoded.clone();
+   |                     ^^^^^^^^ unnecessary method call
+   |
+   = note: the type `&[u8]` which `clone` is being called on is the same as the type returned from `clone`, so the method call does not do anything and can be removed
+
+error: aborting due to 3 previous errors
+
diff --git a/tests/ui/parser/issues/issue-62913.rs b/tests/ui/parser/issues/issue-62913.rs
index 0db06f636c3..a55ef5ac710 100644
--- a/tests/ui/parser/issues/issue-62913.rs
+++ b/tests/ui/parser/issues/issue-62913.rs
@@ -1,4 +1,4 @@
 "\u\\"
 //~^ ERROR incorrect unicode escape sequence
 //~| ERROR invalid trailing slash in literal
-//~| ERROR expected item, found `"\u\\"`
+//~| ERROR expected item, found `"\u\"`
diff --git a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.nn.stderr b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.nn.stderr
index d4f42b787e4..97f346e8c1d 100644
--- a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.nn.stderr
+++ b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.nn.stderr
@@ -4,5 +4,11 @@ error: ~const can only be applied to `#[const_trait]` traits
 LL | trait Bar: ~const Foo {}
    |                   ^^^
 
-error: aborting due to previous error
+error: ~const can only be applied to `#[const_trait]` traits
+  --> $DIR/super-traits-fail-2.rs:11:19
+   |
+LL | trait Bar: ~const Foo {}
+   |                   ^^^
+
+error: aborting due to 2 previous errors
 
diff --git a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.ny.stderr b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.ny.stderr
index d4f42b787e4..97f346e8c1d 100644
--- a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.ny.stderr
+++ b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.ny.stderr
@@ -4,5 +4,11 @@ error: ~const can only be applied to `#[const_trait]` traits
 LL | trait Bar: ~const Foo {}
    |                   ^^^
 
-error: aborting due to previous error
+error: ~const can only be applied to `#[const_trait]` traits
+  --> $DIR/super-traits-fail-2.rs:11:19
+   |
+LL | trait Bar: ~const Foo {}
+   |                   ^^^
+
+error: aborting due to 2 previous errors
 
diff --git a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.rs b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.rs
index d183efde2df..ecb06271cd9 100644
--- a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.rs
+++ b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.rs
@@ -10,6 +10,7 @@ trait Foo {
 #[cfg_attr(any(yy, ny), const_trait)]
 trait Bar: ~const Foo {}
 //[ny,nn]~^ ERROR: ~const can only be applied to `#[const_trait]`
+//[ny,nn]~| ERROR: ~const can only be applied to `#[const_trait]`
 
 const fn foo<T: Bar>(x: &T) {
     x.a();
diff --git a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yn.stderr b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yn.stderr
index 13fc719f28c..c9fa1955498 100644
--- a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yn.stderr
+++ b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yn.stderr
@@ -1,11 +1,11 @@
 error[E0277]: the trait bound `T: ~const Foo` is not satisfied
-  --> $DIR/super-traits-fail-2.rs:15:7
+  --> $DIR/super-traits-fail-2.rs:16:7
    |
 LL |     x.a();
    |       ^ the trait `~const Foo` is not implemented for `T`
    |
 note: the trait `Foo` is implemented for `T`, but that implementation is not `const`
-  --> $DIR/super-traits-fail-2.rs:15:5
+  --> $DIR/super-traits-fail-2.rs:16:5
    |
 LL |     x.a();
    |     ^
diff --git a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yy.stderr b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yy.stderr
index 13fc719f28c..c9fa1955498 100644
--- a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yy.stderr
+++ b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-2.yy.stderr
@@ -1,11 +1,11 @@
 error[E0277]: the trait bound `T: ~const Foo` is not satisfied
-  --> $DIR/super-traits-fail-2.rs:15:7
+  --> $DIR/super-traits-fail-2.rs:16:7
    |
 LL |     x.a();
    |       ^ the trait `~const Foo` is not implemented for `T`
    |
 note: the trait `Foo` is implemented for `T`, but that implementation is not `const`
-  --> $DIR/super-traits-fail-2.rs:15:5
+  --> $DIR/super-traits-fail-2.rs:16:5
    |
 LL |     x.a();
    |     ^
diff --git a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-3.nn.stderr b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-3.nn.stderr
index d433e1cfa69..fdc6b805889 100644
--- a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-3.nn.stderr
+++ b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-3.nn.stderr
@@ -5,10 +5,16 @@ LL | trait Bar: ~const Foo {}
    |                   ^^^
 
 error: ~const can only be applied to `#[const_trait]` traits
-  --> $DIR/super-traits-fail-3.rs:15:24
+  --> $DIR/super-traits-fail-3.rs:12:19
+   |
+LL | trait Bar: ~const Foo {}
+   |                   ^^^
+
+error: ~const can only be applied to `#[const_trait]` traits
+  --> $DIR/super-traits-fail-3.rs:16:24
    |
 LL | const fn foo<T: ~const Bar>(x: &T) {
    |                        ^^^
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors
 
diff --git a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-3.ny.stderr b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-3.ny.stderr
index 2a7e8e00bc7..7375b8c819c 100644
--- a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-3.ny.stderr
+++ b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-3.ny.stderr
@@ -4,5 +4,11 @@ error: ~const can only be applied to `#[const_trait]` traits
 LL | trait Bar: ~const Foo {}
    |                   ^^^
 
-error: aborting due to previous error
+error: ~const can only be applied to `#[const_trait]` traits
+  --> $DIR/super-traits-fail-3.rs:12:19
+   |
+LL | trait Bar: ~const Foo {}
+   |                   ^^^
+
+error: aborting due to 2 previous errors
 
diff --git a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-3.rs b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-3.rs
index 70d2936d3b2..8cf64944ac1 100644
--- a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-3.rs
+++ b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-3.rs
@@ -11,6 +11,7 @@ trait Foo {
 #[cfg_attr(any(yy, ny), const_trait)]
 trait Bar: ~const Foo {}
 //[ny,nn]~^ ERROR: ~const can only be applied to `#[const_trait]`
+//[ny,nn]~| ERROR: ~const can only be applied to `#[const_trait]`
 
 const fn foo<T: ~const Bar>(x: &T) {
     //[yn,nn]~^ ERROR: ~const can only be applied to `#[const_trait]`
diff --git a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-3.yn.stderr b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-3.yn.stderr
index e5978c12a09..7a152914b69 100644
--- a/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-3.yn.stderr
+++ b/tests/ui/rfc-2632-const-trait-impl/super-traits-fail-3.yn.stderr
@@ -1,5 +1,5 @@
 error: ~const can only be applied to `#[const_trait]` traits
-  --> $DIR/super-traits-fail-3.rs:15:24
+  --> $DIR/super-traits-fail-3.rs:16:24
    |
 LL | const fn foo<T: ~const Bar>(x: &T) {
    |                        ^^^
diff --git a/tests/ui/traits/issue-38404.rs b/tests/ui/traits/issue-38404.rs
index 1a92acc3404..05921b2c36e 100644
--- a/tests/ui/traits/issue-38404.rs
+++ b/tests/ui/traits/issue-38404.rs
@@ -2,5 +2,6 @@ trait A<T>: std::ops::Add<Self> + Sized {}
 trait B<T>: A<T> {}
 trait C<T>: A<dyn B<T, Output=usize>> {}
 //~^ ERROR the trait `B` cannot be made into an object
+//~| ERROR the trait `B` cannot be made into an object
 
 fn main() {}
diff --git a/tests/ui/traits/issue-38404.stderr b/tests/ui/traits/issue-38404.stderr
index d7721d7e69c..f8625f53b78 100644
--- a/tests/ui/traits/issue-38404.stderr
+++ b/tests/ui/traits/issue-38404.stderr
@@ -12,6 +12,20 @@ LL | trait A<T>: std::ops::Add<Self> + Sized {}
 LL | trait B<T>: A<T> {}
    |       - this trait cannot be made into an object...
 
-error: aborting due to previous error
+error[E0038]: the trait `B` cannot be made into an object
+  --> $DIR/issue-38404.rs:3:15
+   |
+LL | trait C<T>: A<dyn B<T, Output=usize>> {}
+   |               ^^^^^^^^^^^^^^^^^^^^^^ `B` cannot be made into an object
+   |
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/issue-38404.rs:1:13
+   |
+LL | trait A<T>: std::ops::Add<Self> + Sized {}
+   |             ^^^^^^^^^^^^^^^^^^^ ...because it uses `Self` as a type parameter
+LL | trait B<T>: A<T> {}
+   |       - this trait cannot be made into an object...
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/typeck/typeck-builtin-bound-type-parameters.rs b/tests/ui/typeck/typeck-builtin-bound-type-parameters.rs
index 7ff9199f63c..e7e62c07739 100644
--- a/tests/ui/typeck/typeck-builtin-bound-type-parameters.rs
+++ b/tests/ui/typeck/typeck-builtin-bound-type-parameters.rs
@@ -3,6 +3,7 @@ fn foo1<T:Copy<U>, U>(x: T) {}
 
 trait Trait: Copy<dyn Send> {}
 //~^ ERROR trait takes 0 generic arguments but 1 generic argument was supplied
+//~| ERROR trait takes 0 generic arguments but 1 generic argument was supplied
 
 struct MyStruct1<T: Copy<T>>;
 //~^ ERROR trait takes 0 generic arguments but 1 generic argument was supplied
diff --git a/tests/ui/typeck/typeck-builtin-bound-type-parameters.stderr b/tests/ui/typeck/typeck-builtin-bound-type-parameters.stderr
index a71fd953658..a3517af877c 100644
--- a/tests/ui/typeck/typeck-builtin-bound-type-parameters.stderr
+++ b/tests/ui/typeck/typeck-builtin-bound-type-parameters.stderr
@@ -15,7 +15,15 @@ LL | trait Trait: Copy<dyn Send> {}
    |              expected 0 generic arguments
 
 error[E0107]: trait takes 0 generic arguments but 1 generic argument was supplied
-  --> $DIR/typeck-builtin-bound-type-parameters.rs:7:21
+  --> $DIR/typeck-builtin-bound-type-parameters.rs:4:14
+   |
+LL | trait Trait: Copy<dyn Send> {}
+   |              ^^^^---------- help: remove these generics
+   |              |
+   |              expected 0 generic arguments
+
+error[E0107]: trait takes 0 generic arguments but 1 generic argument was supplied
+  --> $DIR/typeck-builtin-bound-type-parameters.rs:8:21
    |
 LL | struct MyStruct1<T: Copy<T>>;
    |                     ^^^^--- help: remove these generics
@@ -23,7 +31,7 @@ LL | struct MyStruct1<T: Copy<T>>;
    |                     expected 0 generic arguments
 
 error[E0107]: trait takes 0 lifetime arguments but 1 lifetime argument was supplied
-  --> $DIR/typeck-builtin-bound-type-parameters.rs:10:25
+  --> $DIR/typeck-builtin-bound-type-parameters.rs:11:25
    |
 LL | struct MyStruct2<'a, T: Copy<'a>>;
    |                         ^^^^---- help: remove these generics
@@ -31,7 +39,7 @@ LL | struct MyStruct2<'a, T: Copy<'a>>;
    |                         expected 0 lifetime arguments
 
 error[E0107]: trait takes 0 lifetime arguments but 1 lifetime argument was supplied
-  --> $DIR/typeck-builtin-bound-type-parameters.rs:13:15
+  --> $DIR/typeck-builtin-bound-type-parameters.rs:14:15
    |
 LL | fn foo2<'a, T:Copy<'a, U>, U>(x: T) {}
    |               ^^^^ -- help: remove this lifetime argument
@@ -39,13 +47,13 @@ LL | fn foo2<'a, T:Copy<'a, U>, U>(x: T) {}
    |               expected 0 lifetime arguments
 
 error[E0107]: trait takes 0 generic arguments but 1 generic argument was supplied
-  --> $DIR/typeck-builtin-bound-type-parameters.rs:13:15
+  --> $DIR/typeck-builtin-bound-type-parameters.rs:14:15
    |
 LL | fn foo2<'a, T:Copy<'a, U>, U>(x: T) {}
    |               ^^^^     - help: remove this generic argument
    |               |
    |               expected 0 generic arguments
 
-error: aborting due to 6 previous errors
+error: aborting due to 7 previous errors
 
 For more information about this error, try `rustc --explain E0107`.