Auto merge of #82868 - petrochenkov:bto, r=estebank

Report missing cases of `bare_trait_objects`

Fixes https://github.com/rust-lang/rust/issues/65371

39 files changed, 192 insertions, 93 deletions

diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index ee7367d408d..7e82d7ff77d 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -1964,7 +1964,7 @@ impl TyKind {
 }
 
 /// Syntax used to declare a trait object.
-#[derive(Clone, Copy, PartialEq, Encodable, Decodable, Debug)]
+#[derive(Clone, Copy, PartialEq, Encodable, Decodable, Debug, HashStable_Generic)]
 pub enum TraitObjectSyntax {
     Dyn,
     None,
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 44f05cbf436..f9872f84e12 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -1396,7 +1396,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 if kind != TraitObjectSyntax::Dyn {
                     self.maybe_lint_bare_trait(t.span, t.id, false);
                 }
-                hir::TyKind::TraitObject(bounds, lifetime_bound)
+                hir::TyKind::TraitObject(bounds, lifetime_bound, kind)
             }
             TyKind::ImplTrait(def_node_id, ref bounds) => {
                 let span = t.span;
@@ -2648,6 +2648,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         hir::TyKind::TraitObject(
                             arena_vec![self; principal],
                             self.elided_dyn_bound(span),
+                            TraitObjectSyntax::None,
                         )
                     }
                     _ => hir::TyKind::Path(hir::QPath::Resolved(None, path)),
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index 2b84d4658f9..d03584d49a5 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -6,7 +6,7 @@ use crate::{itemlikevisit, LangItem};
 
 use rustc_ast::util::parser::ExprPrecedence;
 use rustc_ast::{self as ast, CrateSugar, LlvmAsmDialect};
-use rustc_ast::{Attribute, FloatTy, IntTy, Label, LitKind, StrStyle, UintTy};
+use rustc_ast::{Attribute, FloatTy, IntTy, Label, LitKind, StrStyle, TraitObjectSyntax, UintTy};
 pub use rustc_ast::{BorrowKind, ImplPolarity, IsAuto};
 pub use rustc_ast::{CaptureBy, Movability, Mutability};
 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
@@ -2327,7 +2327,7 @@ pub enum TyKind<'hir> {
     OpaqueDef(ItemId, &'hir [GenericArg<'hir>]),
     /// A trait object type `Bound1 + Bound2 + Bound3`
     /// where `Bound` is a trait or a lifetime.
-    TraitObject(&'hir [PolyTraitRef<'hir>], Lifetime),
+    TraitObject(&'hir [PolyTraitRef<'hir>], Lifetime, TraitObjectSyntax),
     /// Unused for now.
     Typeof(AnonConst),
     /// `TyKind::Infer` means the type should be inferred instead of it having been
diff --git a/compiler/rustc_hir/src/intravisit.rs b/compiler/rustc_hir/src/intravisit.rs
index 1ed8ab044fe..701e4a63293 100644
--- a/compiler/rustc_hir/src/intravisit.rs
+++ b/compiler/rustc_hir/src/intravisit.rs
@@ -709,7 +709,7 @@ pub fn walk_ty<'v, V: Visitor<'v>>(visitor: &mut V, typ: &'v Ty<'v>) {
             visitor.visit_ty(ty);
             visitor.visit_anon_const(length)
         }
-        TyKind::TraitObject(bounds, ref lifetime) => {
+        TyKind::TraitObject(bounds, ref lifetime, _syntax) => {
             for bound in bounds {
                 visitor.visit_poly_trait_ref(bound, TraitBoundModifier::None);
             }
diff --git a/compiler/rustc_hir_pretty/src/lib.rs b/compiler/rustc_hir_pretty/src/lib.rs
index 9eab6cab64d..b37a3e19b84 100644
--- a/compiler/rustc_hir_pretty/src/lib.rs
+++ b/compiler/rustc_hir_pretty/src/lib.rs
@@ -410,7 +410,10 @@ impl<'a> State<'a> {
             }
             hir::TyKind::OpaqueDef(..) => self.s.word("/*impl Trait*/"),
             hir::TyKind::Path(ref qpath) => self.print_qpath(qpath, false),
-            hir::TyKind::TraitObject(bounds, ref lifetime) => {
+            hir::TyKind::TraitObject(bounds, ref lifetime, syntax) => {
+                if syntax == ast::TraitObjectSyntax::Dyn {
+                    self.word_space("dyn");
+                }
                 let mut first = true;
                 for bound in bounds {
                     if first {
diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/find_anon_type.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/find_anon_type.rs
index d9ab8319045..35b9bc96f13 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/find_anon_type.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/find_anon_type.rs
@@ -99,7 +99,7 @@ impl Visitor<'tcx> for FindNestedTypeVisitor<'tcx> {
                 return;
             }
 
-            hir::TyKind::TraitObject(bounds, _) => {
+            hir::TyKind::TraitObject(bounds, ..) => {
                 for bound in bounds {
                     self.current_index.shift_in(1);
                     self.visit_poly_trait_ref(bound, hir::TraitBoundModifier::None);
diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs
index fa0d5b83013..1e926989263 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs
@@ -292,7 +292,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                         );
                     }
                 }
-                TyKind::TraitObject(_, lt) => match lt.name {
+                TyKind::TraitObject(_, lt, _) => match lt.name {
                     LifetimeName::ImplicitObjectLifetimeDefault => {
                         err.span_suggestion_verbose(
                             fn_return.span.shrink_to_hi(),
@@ -498,6 +498,7 @@ impl<'tcx> Visitor<'tcx> for HirTraitObjectVisitor {
         if let TyKind::TraitObject(
             poly_trait_refs,
             Lifetime { name: LifetimeName::ImplicitObjectLifetimeDefault, .. },
+            _,
         ) = t.kind
         {
             for ptr in poly_trait_refs {
diff --git a/compiler/rustc_middle/src/ty/diagnostics.rs b/compiler/rustc_middle/src/ty/diagnostics.rs
index f41bb7e6d63..982c8a354b4 100644
--- a/compiler/rustc_middle/src/ty/diagnostics.rs
+++ b/compiler/rustc_middle/src/ty/diagnostics.rs
@@ -314,6 +314,7 @@ impl<'v> hir::intravisit::Visitor<'v> for TraitObjectVisitor<'v> {
                         hir::LifetimeName::ImplicitObjectLifetimeDefault | hir::LifetimeName::Static,
                     ..
                 },
+                _,
             ) => {
                 self.0.push(ty);
             }
diff --git a/compiler/rustc_resolve/src/late/lifetimes.rs b/compiler/rustc_resolve/src/late/lifetimes.rs
index 4f92532e3a6..2c61c0963ae 100644
--- a/compiler/rustc_resolve/src/late/lifetimes.rs
+++ b/compiler/rustc_resolve/src/late/lifetimes.rs
@@ -540,7 +540,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
                 self.missing_named_lifetime_spots.pop();
                 self.is_in_fn_syntax = was_in_fn_syntax;
             }
-            hir::TyKind::TraitObject(bounds, ref lifetime) => {
+            hir::TyKind::TraitObject(bounds, ref lifetime, _) => {
                 debug!("visit_ty: TraitObject(bounds={:?}, lifetime={:?})", bounds, lifetime);
                 for bound in bounds {
                     self.visit_poly_trait_ref(bound, hir::TraitBoundModifier::None);
@@ -2299,7 +2299,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
                     self.outer_index.shift_in(1);
                 }
                 match ty.kind {
-                    hir::TyKind::TraitObject(bounds, ref lifetime) => {
+                    hir::TyKind::TraitObject(bounds, ref lifetime, _) => {
                         for bound in bounds {
                             self.visit_poly_trait_ref(bound, hir::TraitBoundModifier::None);
                         }
diff --git a/compiler/rustc_trait_selection/src/infer.rs b/compiler/rustc_trait_selection/src/infer.rs
index da66fbc8587..a9ffb5542b6 100644
--- a/compiler/rustc_trait_selection/src/infer.rs
+++ b/compiler/rustc_trait_selection/src/infer.rs
@@ -124,7 +124,7 @@ impl<'tcx> InferCtxtBuilderExt<'tcx> for InferCtxtBuilder<'tcx> {
             DUMMY_SP,
             canonical_key,
             |ref infcx, key, canonical_inference_vars| {
-                let mut fulfill_cx = TraitEngine::new(infcx.tcx);
+                let mut fulfill_cx = <dyn TraitEngine<'_>>::new(infcx.tcx);
                 let value = operation(infcx, &mut *fulfill_cx, key)?;
                 infcx.make_canonicalized_query_response(
                     canonical_inference_vars,
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs
index 68356ce73aa..4f5476ca5d0 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs
@@ -62,7 +62,7 @@ fn scrape_region_constraints<'tcx, R>(
     infcx: &InferCtxt<'_, 'tcx>,
     op: impl FnOnce() -> Fallible<InferOk<'tcx, R>>,
 ) -> Fallible<(R, Option<Rc<QueryRegionConstraints<'tcx>>>)> {
-    let mut fulfill_cx = TraitEngine::new(infcx.tcx);
+    let mut fulfill_cx = <dyn TraitEngine<'_>>::new(infcx.tcx);
     let dummy_body_id = ObligationCause::dummy().body_id;
 
     // During NLL, we expect that nobody will register region
diff --git a/compiler/rustc_traits/src/dropck_outlives.rs b/compiler/rustc_traits/src/dropck_outlives.rs
index cfcbc77c172..9d5b9d7357f 100644
--- a/compiler/rustc_traits/src/dropck_outlives.rs
+++ b/compiler/rustc_traits/src/dropck_outlives.rs
@@ -75,7 +75,7 @@ fn dropck_outlives<'tcx>(
             // Set used to detect infinite recursion.
             let mut ty_set = FxHashSet::default();
 
-            let mut fulfill_cx = TraitEngine::new(infcx.tcx);
+            let mut fulfill_cx = <dyn TraitEngine<'_>>::new(infcx.tcx);
 
             let cause = ObligationCause::dummy();
             let mut constraints = DtorckConstraint::empty();
diff --git a/compiler/rustc_typeck/src/astconv/mod.rs b/compiler/rustc_typeck/src/astconv/mod.rs
index a973b56f7d6..7c5398003f3 100644
--- a/compiler/rustc_typeck/src/astconv/mod.rs
+++ b/compiler/rustc_typeck/src/astconv/mod.rs
@@ -1608,6 +1608,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
     // the whole path.
     // Will fail except for `T::A` and `Self::A`; i.e., if `qself_ty`/`qself_def` are not a type
     // parameter or `Self`.
+    // NOTE: When this function starts resolving `Trait::AssocTy` successfully
+    // it should also start reportint the `BARE_TRAIT_OBJECTS` lint.
     pub fn associated_path_to_ty(
         &self,
         hir_ref_id: hir::HirId,
@@ -2201,7 +2203,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     Some(ast_ty),
                 ))
             }
-            hir::TyKind::TraitObject(ref bounds, ref lifetime) => {
+            hir::TyKind::TraitObject(ref bounds, ref lifetime, _) => {
                 self.conv_object_ty_poly_trait_ref(ast_ty.span, bounds, lifetime, borrowed)
             }
             hir::TyKind::Path(hir::QPath::Resolved(ref maybe_qself, ref path)) => {
diff --git a/compiler/rustc_typeck/src/check/coercion.rs b/compiler/rustc_typeck/src/check/coercion.rs
index 32b3d0b0595..94aee87364a 100644
--- a/compiler/rustc_typeck/src/check/coercion.rs
+++ b/compiler/rustc_typeck/src/check/coercion.rs
@@ -1554,7 +1554,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
         if let hir::FnRetTy::Return(ty) = fn_output {
             // Get the return type.
             if let hir::TyKind::OpaqueDef(..) = ty.kind {
-                let ty = AstConv::ast_ty_to_ty(fcx, ty);
+                let ty = <dyn AstConv<'_>>::ast_ty_to_ty(fcx, ty);
                 // Get the `impl Trait`'s `DefId`.
                 if let ty::Opaque(def_id, _) = ty.kind() {
                     let hir_id = fcx.tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
@@ -1616,7 +1616,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
     fn is_return_ty_unsized(&self, fcx: &FnCtxt<'a, 'tcx>, blk_id: hir::HirId) -> bool {
         if let Some((fn_decl, _)) = fcx.get_fn_decl(blk_id) {
             if let hir::FnRetTy::Return(ty) = fn_decl.output {
-                let ty = AstConv::ast_ty_to_ty(fcx, ty);
+                let ty = <dyn AstConv<'_>>::ast_ty_to_ty(fcx, ty);
                 if let ty::Dynamic(..) = ty.kind() {
                     return true;
                 }
diff --git a/compiler/rustc_typeck/src/check/dropck.rs b/compiler/rustc_typeck/src/check/dropck.rs
index 4c3c4fd4470..4d74962d28e 100644
--- a/compiler/rustc_typeck/src/check/dropck.rs
+++ b/compiler/rustc_typeck/src/check/dropck.rs
@@ -77,7 +77,7 @@ fn ensure_drop_params_and_item_params_correspond<'tcx>(
     tcx.infer_ctxt().enter(|ref infcx| {
         let impl_param_env = tcx.param_env(self_type_did);
         let tcx = infcx.tcx;
-        let mut fulfillment_cx = TraitEngine::new(tcx);
+        let mut fulfillment_cx = <dyn TraitEngine<'_>>::new(tcx);
 
         let named_type = tcx.type_of(self_type_did);
 
diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
index 84ce6964f04..dc8a804bfea 100644
--- a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
+++ b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
@@ -6,6 +6,7 @@ use crate::check::callee::{self, DeferredCallResolution};
 use crate::check::method::{self, MethodCallee, SelfSource};
 use crate::check::{BreakableCtxt, Diverges, Expectation, FallbackMode, FnCtxt, LocalTy};
 
+use rustc_ast::TraitObjectSyntax;
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::{Applicability, DiagnosticBuilder, ErrorReported};
@@ -13,7 +14,7 @@ use rustc_hir as hir;
 use rustc_hir::def::{CtorOf, DefKind, Res};
 use rustc_hir::def_id::DefId;
 use rustc_hir::lang_items::LangItem;
-use rustc_hir::{ExprKind, GenericArg, Node, QPath};
+use rustc_hir::{ExprKind, GenericArg, Node, QPath, TyKind};
 use rustc_infer::infer::canonical::{Canonical, OriginalQueryValues, QueryResponse};
 use rustc_infer::infer::error_reporting::TypeAnnotationNeeded::E0282;
 use rustc_infer::infer::{InferOk, InferResult};
@@ -26,7 +27,9 @@ use rustc_middle::ty::{
     self, AdtKind, CanonicalUserType, DefIdTree, GenericParamDefKind, ToPolyTraitRef, ToPredicate,
     Ty, UserType,
 };
-use rustc_session::{lint, parse::feature_err};
+use rustc_session::lint;
+use rustc_session::lint::builtin::BARE_TRAIT_OBJECTS;
+use rustc_session::parse::feature_err;
 use rustc_span::source_map::{original_sp, DUMMY_SP};
 use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::{self, BytePos, MultiSpan, Span};
@@ -472,7 +475,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     }
 
     pub fn to_ty(&self, ast_t: &hir::Ty<'_>) -> Ty<'tcx> {
-        let t = AstConv::ast_ty_to_ty(self, ast_t);
+        let t = <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_t);
         self.register_wf_obligation(t.into(), ast_t.span, traits::MiscObligation);
         t
     }
@@ -854,7 +857,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         // out unconstrained or ambiguous, as we're
                         // just trying to get hints here.
                         self.save_and_restore_in_snapshot_flag(|_| {
-                            let mut fulfill = TraitEngine::new(self.tcx);
+                            let mut fulfill = <dyn TraitEngine<'_>>::new(self.tcx);
                             for obligation in ok.obligations {
                                 fulfill.register_predicate_obligation(self, obligation);
                             }
@@ -947,6 +950,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             result
         });
 
+        if result.is_ok() {
+            self.maybe_lint_bare_trait(qpath, hir_id);
+        }
+
         // Write back the new resolution.
         self.write_resolution(hir_id, result);
         (
@@ -956,6 +963,29 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         )
     }
 
+    fn maybe_lint_bare_trait(&self, qpath: &QPath<'_>, hir_id: hir::HirId) {
+        if let QPath::TypeRelative(self_ty, _) = qpath {
+            if let TyKind::TraitObject([poly_trait_ref, ..], _, TraitObjectSyntax::None) =
+                self_ty.kind
+            {
+                self.tcx.struct_span_lint_hir(BARE_TRAIT_OBJECTS, hir_id, self_ty.span, |lint| {
+                    let mut db = lint
+                        .build(&format!("trait objects without an explicit `dyn` are deprecated"));
+                    let (sugg, app) = match self.tcx.sess.source_map().span_to_snippet(self_ty.span)
+                    {
+                        Ok(s) if poly_trait_ref.trait_ref.path.is_global() => {
+                            (format!("<dyn ({})>", s), Applicability::MachineApplicable)
+                        }
+                        Ok(s) => (format!("<dyn {}>", s), Applicability::MachineApplicable),
+                        Err(_) => ("<dyn <type>>".to_string(), Applicability::HasPlaceholders),
+                    };
+                    db.span_suggestion(self_ty.span, "use `dyn`", sugg, app);
+                    db.emit()
+                });
+            }
+        }
+    }
+
     /// Given a function `Node`, return its `FnDecl` if it exists, or `None` otherwise.
     pub(in super::super) fn get_node_fn_decl(
         &self,
@@ -1174,9 +1204,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         let path_segs = match res {
             Res::Local(_) | Res::SelfCtor(_) => vec![],
-            Res::Def(kind, def_id) => {
-                AstConv::def_ids_for_value_path_segments(self, segments, self_ty, kind, def_id)
-            }
+            Res::Def(kind, def_id) => <dyn AstConv<'_>>::def_ids_for_value_path_segments(
+                self, segments, self_ty, kind, def_id,
+            ),
             _ => bug!("instantiate_value_path on {:?}", res),
         };
 
@@ -1219,7 +1249,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // errors if type parameters are provided in an inappropriate place.
 
         let generic_segs: FxHashSet<_> = path_segs.iter().map(|PathSeg(_, index)| index).collect();
-        let generics_has_err = AstConv::prohibit_generics(
+        let generics_has_err = <dyn AstConv<'_>>::prohibit_generics(
             self,
             segments.iter().enumerate().filter_map(|(index, seg)| {
                 if !generic_segs.contains(&index) || is_alias_variant_ctor {
@@ -1262,7 +1292,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             if let GenericArgCountResult {
                 correct: Err(GenericArgCountMismatch { reported: Some(_), .. }),
                 ..
-            } = AstConv::check_generic_arg_count_for_call(
+            } = <dyn AstConv<'_>>::check_generic_arg_count_for_call(
                 tcx,
                 span,
                 def_id,
@@ -1370,7 +1400,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             ) -> subst::GenericArg<'tcx> {
                 match (&param.kind, arg) {
                     (GenericParamDefKind::Lifetime, GenericArg::Lifetime(lt)) => {
-                        AstConv::ast_region_to_region(self.fcx, lt, Some(param)).into()
+                        <dyn AstConv<'_>>::ast_region_to_region(self.fcx, lt, Some(param)).into()
                     }
                     (GenericParamDefKind::Type { .. }, GenericArg::Type(ty)) => {
                         self.fcx.to_ty(ty).into()
@@ -1423,7 +1453,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
 
         let substs = self_ctor_substs.unwrap_or_else(|| {
-            AstConv::create_substs_for_generic_args(
+            <dyn AstConv<'_>>::create_substs_for_generic_args(
                 tcx,
                 def_id,
                 &[][..],
diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs b/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
index 528a6d1bd52..c92c7f7ad0b 100644
--- a/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
+++ b/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
@@ -875,7 +875,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         match *qpath {
             QPath::Resolved(ref maybe_qself, ref path) => {
                 let self_ty = maybe_qself.as_ref().map(|qself| self.to_ty(qself));
-                let ty = AstConv::res_to_ty(self, self_ty, path, true);
+                let ty = <dyn AstConv<'_>>::res_to_ty(self, self_ty, path, true);
                 (path.res, ty)
             }
             QPath::TypeRelative(ref qself, ref segment) => {
@@ -886,8 +886,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 } else {
                     Res::Err
                 };
-                let result =
-                    AstConv::associated_path_to_ty(self, hir_id, path_span, ty, res, segment, true);
+                let result = <dyn AstConv<'_>>::associated_path_to_ty(
+                    self, hir_id, path_span, ty, res, segment, true,
+                );
                 let ty = result.map(|(ty, _, _)| ty).unwrap_or_else(|_| self.tcx().ty_error());
                 let result = result.map(|(_, kind, def_id)| (kind, def_id));
 
@@ -1000,7 +1001,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                         // would trigger in `is_send::<T::AssocType>();`
                                         // from `typeck-default-trait-impl-assoc-type.rs`.
                                     } else {
-                                        let ty = AstConv::ast_ty_to_ty(self, hir_ty);
+                                        let ty = <dyn AstConv<'_>>::ast_ty_to_ty(self, hir_ty);
                                         let ty = self.resolve_vars_if_possible(ty);
                                         if ty == predicate.self_ty() {
                                             error.obligation.cause.make_mut().span = hir_ty.span;
diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs b/compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs
index 9f15993e471..f90159efb5c 100644
--- a/compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs
+++ b/compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs
@@ -461,7 +461,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 // are not, the expectation must have been caused by something else.
                 debug!("suggest_missing_return_type: return type {:?} node {:?}", ty, ty.kind);
                 let sp = ty.span;
-                let ty = AstConv::ast_ty_to_ty(self, ty);
+                let ty = <dyn AstConv<'_>>::ast_ty_to_ty(self, ty);
                 debug!("suggest_missing_return_type: return type {:?}", ty);
                 debug!("suggest_missing_return_type: expected type {:?}", ty);
                 if ty.kind() == expected.kind() {
@@ -486,7 +486,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
         let found = self.resolve_vars_with_obligations(found);
         if let hir::FnRetTy::Return(ty) = fn_decl.output {
-            let ty = AstConv::ast_ty_to_ty(self, ty);
+            let ty = <dyn AstConv<'_>>::ast_ty_to_ty(self, ty);
             let ty = self.tcx.erase_late_bound_regions(Binder::bind(ty));
             let ty = self.normalize_associated_types_in(expr.span, ty);
             if self.can_coerce(found, ty) {
diff --git a/compiler/rustc_typeck/src/check/inherited.rs b/compiler/rustc_typeck/src/check/inherited.rs
index 0011a3fc71b..1dacbade1bd 100644
--- a/compiler/rustc_typeck/src/check/inherited.rs
+++ b/compiler/rustc_typeck/src/check/inherited.rs
@@ -117,7 +117,7 @@ impl Inherited<'a, 'tcx> {
                 maybe_typeck_results: infcx.in_progress_typeck_results,
             },
             infcx,
-            fulfillment_cx: RefCell::new(TraitEngine::new(tcx)),
+            fulfillment_cx: RefCell::new(<dyn TraitEngine<'_>>::new(tcx)),
             locals: RefCell::new(Default::default()),
             deferred_sized_obligations: RefCell::new(Vec::new()),
             deferred_call_resolutions: RefCell::new(Default::default()),
diff --git a/compiler/rustc_typeck/src/check/method/confirm.rs b/compiler/rustc_typeck/src/check/method/confirm.rs
index 7a80524f1b7..4a2dd6faf0c 100644
--- a/compiler/rustc_typeck/src/check/method/confirm.rs
+++ b/compiler/rustc_typeck/src/check/method/confirm.rs
@@ -314,7 +314,7 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
         // variables.
         let generics = self.tcx.generics_of(pick.item.def_id);
 
-        let arg_count_correct = AstConv::check_generic_arg_count_for_call(
+        let arg_count_correct = <dyn AstConv<'_>>::check_generic_arg_count_for_call(
             self.tcx,
             self.span,
             pick.item.def_id,
@@ -352,7 +352,8 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
             ) -> subst::GenericArg<'tcx> {
                 match (&param.kind, arg) {
                     (GenericParamDefKind::Lifetime, GenericArg::Lifetime(lt)) => {
-                        AstConv::ast_region_to_region(self.cfcx.fcx, lt, Some(param)).into()
+                        <dyn AstConv<'_>>::ast_region_to_region(self.cfcx.fcx, lt, Some(param))
+                            .into()
                     }
                     (GenericParamDefKind::Type { .. }, GenericArg::Type(ty)) => {
                         self.cfcx.to_ty(ty).into()
@@ -373,7 +374,7 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
                 self.cfcx.var_for_def(self.cfcx.span, param)
             }
         }
-        AstConv::create_substs_for_generic_args(
+        <dyn AstConv<'_>>::create_substs_for_generic_args(
             self.tcx,
             pick.item.def_id,
             parent_substs,
diff --git a/compiler/rustc_typeck/src/check/mod.rs b/compiler/rustc_typeck/src/check/mod.rs
index 85bd45f0ca8..ad9bb703779 100644
--- a/compiler/rustc_typeck/src/check/mod.rs
+++ b/compiler/rustc_typeck/src/check/mod.rs
@@ -495,7 +495,7 @@ fn typeck_with_fallback<'tcx>(
         let fcx = if let (Some(header), Some(decl)) = (fn_header, fn_decl) {
             let fn_sig = if crate::collect::get_infer_ret_ty(&decl.output).is_some() {
                 let fcx = FnCtxt::new(&inh, param_env, body.value.hir_id);
-                AstConv::ty_of_fn(
+                <dyn AstConv<'_>>::ty_of_fn(
                     &fcx,
                     header.unsafety,
                     header.abi,
@@ -527,7 +527,7 @@ fn typeck_with_fallback<'tcx>(
             let fcx = FnCtxt::new(&inh, param_env, body.value.hir_id);
             let expected_type = body_ty
                 .and_then(|ty| match ty.kind {
-                    hir::TyKind::Infer => Some(AstConv::ast_ty_to_ty(&fcx, ty)),
+                    hir::TyKind::Infer => Some(<dyn AstConv<'_>>::ast_ty_to_ty(&fcx, ty)),
                     _ => None,
                 })
                 .unwrap_or_else(|| match tcx.hir().get(id) {
diff --git a/compiler/rustc_typeck/src/coherence/builtin.rs b/compiler/rustc_typeck/src/coherence/builtin.rs
index 5b44cb7eae5..8cae61e8c22 100644
--- a/compiler/rustc_typeck/src/coherence/builtin.rs
+++ b/compiler/rustc_typeck/src/coherence/builtin.rs
@@ -246,7 +246,7 @@ fn visit_implementation_of_dispatch_from_dyn(tcx: TyCtxt<'_>, impl_did: LocalDef
                     ))
                     .emit();
                 } else {
-                    let mut fulfill_cx = TraitEngine::new(infcx.tcx);
+                    let mut fulfill_cx = <dyn TraitEngine<'_>>::new(infcx.tcx);
 
                     for field in coerced_fields {
                         let predicate = predicate_for_trait_def(
@@ -506,7 +506,7 @@ pub fn coerce_unsized_info(tcx: TyCtxt<'tcx>, impl_did: DefId) -> CoerceUnsizedI
             }
         };
 
-        let mut fulfill_cx = TraitEngine::new(infcx.tcx);
+        let mut fulfill_cx = <dyn TraitEngine<'_>>::new(infcx.tcx);
 
         // Register an obligation for `A: Trait<B>`.
         let cause = traits::ObligationCause::misc(span, impl_hir_id);
diff --git a/compiler/rustc_typeck/src/collect.rs b/compiler/rustc_typeck/src/collect.rs
index a175da32706..e5136355ca9 100644
--- a/compiler/rustc_typeck/src/collect.rs
+++ b/compiler/rustc_typeck/src/collect.rs
@@ -310,7 +310,7 @@ impl ItemCtxt<'tcx> {
     }
 
     pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
-        AstConv::ast_ty_to_ty(self, ast_ty)
+        <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_ty)
     }
 
     pub fn hir_id(&self) -> hir::HirId {
@@ -1096,7 +1096,7 @@ fn super_predicates_that_define_assoc_type(
         // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
         let self_param_ty = tcx.types.self_param;
         let superbounds1 = if let Some(assoc_name) = assoc_name {
-            AstConv::compute_bounds_that_match_assoc_type(
+            <dyn AstConv<'_>>::compute_bounds_that_match_assoc_type(
                 &icx,
                 self_param_ty,
                 &bounds,
@@ -1105,7 +1105,13 @@ fn super_predicates_that_define_assoc_type(
                 assoc_name,
             )
         } else {
-            AstConv::compute_bounds(&icx, self_param_ty, &bounds, SizedByDefault::No, item.span)
+            <dyn AstConv<'_>>::compute_bounds(
+                &icx,
+                self_param_ty,
+                &bounds,
+                SizedByDefault::No,
+                item.span,
+            )
         };
 
         let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
@@ -1689,7 +1695,7 @@ fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
 
                     ty::Binder::bind(fn_sig)
                 }
-                None => AstConv::ty_of_fn(
+                None => <dyn AstConv<'_>>::ty_of_fn(
                     &icx,
                     sig.header.unsafety,
                     sig.header.abi,
@@ -1706,7 +1712,7 @@ fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
             ident,
             generics,
             ..
-        }) => AstConv::ty_of_fn(
+        }) => <dyn AstConv<'_>>::ty_of_fn(
             &icx,
             header.unsafety,
             header.abi,
@@ -1767,7 +1773,7 @@ fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
     match tcx.hir().expect_item(hir_id).kind {
         hir::ItemKind::Impl(ref impl_) => impl_.of_trait.as_ref().map(|ast_trait_ref| {
             let selfty = tcx.type_of(def_id);
-            AstConv::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
+            <dyn AstConv<'_>>::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty)
         }),
         _ => bug!(),
     }
@@ -2018,7 +2024,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP
             GenericParamKind::Lifetime { .. } => {
                 param.bounds.iter().for_each(|bound| match bound {
                     hir::GenericBound::Outlives(lt) => {
-                        let bound = AstConv::ast_region_to_region(&icx, &lt, None);
+                        let bound = <dyn AstConv<'_>>::ast_region_to_region(&icx, &lt, None);
                         let outlives = ty::Binder::bind(ty::OutlivesPredicate(region, bound));
                         predicates.insert((outlives.to_predicate(tcx), lt.span));
                     }
@@ -2041,8 +2047,13 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP
                 index += 1;
 
                 let sized = SizedByDefault::Yes;
-                let bounds =
-                    AstConv::compute_bounds(&icx, param_ty, &param.bounds, sized, param.span);
+                let bounds = <dyn AstConv<'_>>::compute_bounds(
+                    &icx,
+                    param_ty,
+                    &param.bounds,
+                    sized,
+                    param.span,
+                );
                 predicates.extend(bounds.predicates(tcx, param_ty));
             }
             GenericParamKind::Const { .. } => {
@@ -2091,7 +2102,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP
                             };
 
                             let mut bounds = Bounds::default();
-                            let _ = AstConv::instantiate_poly_trait_ref(
+                            let _ = <dyn AstConv<'_>>::instantiate_poly_trait_ref(
                                 &icx,
                                 &poly_trait_ref,
                                 constness,
@@ -2103,7 +2114,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP
 
                         &hir::GenericBound::LangItemTrait(lang_item, span, hir_id, args) => {
                             let mut bounds = Bounds::default();
-                            AstConv::instantiate_lang_item_trait_ref(
+                            <dyn AstConv<'_>>::instantiate_lang_item_trait_ref(
                                 &icx,
                                 lang_item,
                                 span,
@@ -2116,7 +2127,8 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP
                         }
 
                         hir::GenericBound::Outlives(lifetime) => {
-                            let region = AstConv::ast_region_to_region(&icx, lifetime, None);
+                            let region =
+                                <dyn AstConv<'_>>::ast_region_to_region(&icx, lifetime, None);
                             predicates.insert((
                                 ty::Binder::bind(ty::PredicateKind::TypeOutlives(
                                     ty::OutlivesPredicate(ty, region),
@@ -2130,11 +2142,11 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP
             }
 
             hir::WherePredicate::RegionPredicate(region_pred) => {
-                let r1 = AstConv::ast_region_to_region(&icx, &region_pred.lifetime, None);
+                let r1 = <dyn AstConv<'_>>::ast_region_to_region(&icx, &region_pred.lifetime, None);
                 predicates.extend(region_pred.bounds.iter().map(|bound| {
                     let (r2, span) = match bound {
                         hir::GenericBound::Outlives(lt) => {
-                            (AstConv::ast_region_to_region(&icx, lt, None), lt.span)
+                            (<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span)
                         }
                         _ => bug!(),
                     };
@@ -2377,7 +2389,7 @@ fn compute_sig_of_foreign_fn_decl<'tcx>(
     } else {
         hir::Unsafety::Unsafe
     };
-    let fty = AstConv::ty_of_fn(
+    let fty = <dyn AstConv<'_>>::ty_of_fn(
         &ItemCtxt::new(tcx, def_id),
         unsafety,
         abi,
diff --git a/compiler/rustc_typeck/src/collect/item_bounds.rs b/compiler/rustc_typeck/src/collect/item_bounds.rs
index fe18dc5ed0c..a5b36445aae 100644
--- a/compiler/rustc_typeck/src/collect/item_bounds.rs
+++ b/compiler/rustc_typeck/src/collect/item_bounds.rs
@@ -25,7 +25,7 @@ fn associated_type_bounds<'tcx>(
         InternalSubsts::identity_for_item(tcx, assoc_item_def_id),
     );
 
-    let bounds = AstConv::compute_bounds(
+    let bounds = <dyn AstConv<'_>>::compute_bounds(
         &ItemCtxt::new(tcx, assoc_item_def_id),
         item_ty,
         &bounds,
@@ -66,7 +66,7 @@ fn opaque_type_bounds<'tcx>(
         let item_ty =
             tcx.mk_opaque(opaque_def_id, InternalSubsts::identity_for_item(tcx, opaque_def_id));
 
-        let bounds = AstConv::compute_bounds(
+        let bounds = <dyn AstConv<'_>>::compute_bounds(
             &ItemCtxt::new(tcx, opaque_def_id),
             item_ty,
             &bounds,
diff --git a/compiler/rustc_typeck/src/lib.rs b/compiler/rustc_typeck/src/lib.rs
index 29d9df61906..88b47bf5b9c 100644
--- a/compiler/rustc_typeck/src/lib.rs
+++ b/compiler/rustc_typeck/src/lib.rs
@@ -142,7 +142,7 @@ fn require_same_types<'tcx>(
 ) -> bool {
     tcx.infer_ctxt().enter(|ref infcx| {
         let param_env = ty::ParamEnv::empty();
-        let mut fulfill_cx = TraitEngine::new(infcx.tcx);
+        let mut fulfill_cx = <dyn TraitEngine<'_>>::new(infcx.tcx);
         match infcx.at(&cause, param_env).eq(expected, actual) {
             Ok(InferOk { obligations, .. }) => {
                 fulfill_cx.register_predicate_obligations(infcx, obligations);
@@ -444,7 +444,7 @@ pub fn hir_trait_to_predicates<'tcx>(
     let env_def_id = tcx.hir().local_def_id(env_hir_id);
     let item_cx = self::collect::ItemCtxt::new(tcx, env_def_id.to_def_id());
     let mut bounds = Bounds::default();
-    let _ = AstConv::instantiate_poly_trait_ref_inner(
+    let _ = <dyn AstConv<'_>>::instantiate_poly_trait_ref_inner(
         &item_cx,
         hir_trait,
         DUMMY_SP,
diff --git a/library/core/src/any.rs b/library/core/src/any.rs
index eef8f2046d3..98c34f34425 100644
--- a/library/core/src/any.rs
+++ b/library/core/src/any.rs
@@ -285,7 +285,7 @@ impl dyn Any + Send {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn is<T: Any>(&self) -> bool {
-        Any::is::<T>(self)
+        <dyn Any>::is::<T>(self)
     }
 
     /// Forwards to the method defined on the type `Any`.
@@ -309,7 +309,7 @@ impl dyn Any + Send {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn downcast_ref<T: Any>(&self) -> Option<&T> {
-        Any::downcast_ref::<T>(self)
+        <dyn Any>::downcast_ref::<T>(self)
     }
 
     /// Forwards to the method defined on the type `Any`.
@@ -337,7 +337,7 @@ impl dyn Any + Send {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn downcast_mut<T: Any>(&mut self) -> Option<&mut T> {
-        Any::downcast_mut::<T>(self)
+        <dyn Any>::downcast_mut::<T>(self)
     }
 }
 
@@ -363,7 +363,7 @@ impl dyn Any + Send + Sync {
     #[stable(feature = "any_send_sync_methods", since = "1.28.0")]
     #[inline]
     pub fn is<T: Any>(&self) -> bool {
-        Any::is::<T>(self)
+        <dyn Any>::is::<T>(self)
     }
 
     /// Forwards to the method defined on the type `Any`.
@@ -387,7 +387,7 @@ impl dyn Any + Send + Sync {
     #[stable(feature = "any_send_sync_methods", since = "1.28.0")]
     #[inline]
     pub fn downcast_ref<T: Any>(&self) -> Option<&T> {
-        Any::downcast_ref::<T>(self)
+        <dyn Any>::downcast_ref::<T>(self)
     }
 
     /// Forwards to the method defined on the type `Any`.
@@ -415,7 +415,7 @@ impl dyn Any + Send + Sync {
     #[stable(feature = "any_send_sync_methods", since = "1.28.0")]
     #[inline]
     pub fn downcast_mut<T: Any>(&mut self) -> Option<&mut T> {
-        Any::downcast_mut::<T>(self)
+        <dyn Any>::downcast_mut::<T>(self)
     }
 }
 
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index ead9d7d6646..17a961a5f66 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -1477,7 +1477,7 @@ impl Clean<Type> for hir::Ty<'_> {
                 }
             }
             TyKind::Path(_) => clean_qpath(&self, cx),
-            TyKind::TraitObject(ref bounds, ref lifetime) => {
+            TyKind::TraitObject(ref bounds, ref lifetime, _) => {
                 match bounds[0].clean(cx).trait_ {
                     ResolvedPath { path, param_names: None, did, is_generic } => {
                         let mut bounds: Vec<self::GenericBound> = bounds[1..]
diff --git a/src/test/ui/lint/bare-trait-objects-path.rs b/src/test/ui/lint/bare-trait-objects-path.rs
new file mode 100644
index 00000000000..4c961e998df
--- /dev/null
+++ b/src/test/ui/lint/bare-trait-objects-path.rs
@@ -0,0 +1,18 @@
+#![feature(associated_type_defaults)]
+
+trait Assoc {
+    fn func() {}
+    const CONST: u8 = 0;
+    type Ty = u8;
+}
+
+trait Dyn {}
+
+impl Assoc for dyn Dyn {}
+
+fn main() {
+    Dyn::func(); //~ WARN trait objects without an explicit `dyn` are deprecated
+    ::Dyn::func(); //~ WARN trait objects without an explicit `dyn` are deprecated
+    Dyn::CONST; //~ WARN trait objects without an explicit `dyn` are deprecated
+    let _: Dyn::Ty; //~ ERROR ambiguous associated type
+}
diff --git a/src/test/ui/lint/bare-trait-objects-path.stderr b/src/test/ui/lint/bare-trait-objects-path.stderr
new file mode 100644
index 00000000000..0a2dc585828
--- /dev/null
+++ b/src/test/ui/lint/bare-trait-objects-path.stderr
@@ -0,0 +1,29 @@
+error[E0223]: ambiguous associated type
+  --> $DIR/bare-trait-objects-path.rs:17:12
+   |
+LL |     let _: Dyn::Ty;
+   |            ^^^^^^^ help: use fully-qualified syntax: `<dyn Dyn as Trait>::Ty`
+
+warning: trait objects without an explicit `dyn` are deprecated
+  --> $DIR/bare-trait-objects-path.rs:14:5
+   |
+LL |     Dyn::func();
+   |     ^^^ help: use `dyn`: `<dyn Dyn>`
+   |
+   = note: `#[warn(bare_trait_objects)]` on by default
+
+warning: trait objects without an explicit `dyn` are deprecated
+  --> $DIR/bare-trait-objects-path.rs:15:5
+   |
+LL |     ::Dyn::func();
+   |     ^^^^^ help: use `dyn`: `<dyn (::Dyn)>`
+
+warning: trait objects without an explicit `dyn` are deprecated
+  --> $DIR/bare-trait-objects-path.rs:16:5
+   |
+LL |     Dyn::CONST;
+   |     ^^^ help: use `dyn`: `<dyn Dyn>`
+
+error: aborting due to previous error; 3 warnings emitted
+
+For more information about this error, try `rustc --explain E0223`.
diff --git a/src/test/ui/traits/impl.rs b/src/test/ui/traits/impl.rs
index 14796ce19c8..f512d91ebeb 100644
--- a/src/test/ui/traits/impl.rs
+++ b/src/test/ui/traits/impl.rs
@@ -30,8 +30,8 @@ fn main() {
     let x: &dyn T = &42;
 
     x.foo();
-    T::foo(x);
-    T::bar();
+    <dyn T>::foo(x);
+    <dyn T>::bar();
 
     unsafe { assert_eq!(COUNT, 12); }
 
diff --git a/src/test/ui/traits/inheritance/repeated-supertrait-ambig.rs b/src/test/ui/traits/inheritance/repeated-supertrait-ambig.rs
index 6aaef8a305b..727897d20cb 100644
--- a/src/test/ui/traits/inheritance/repeated-supertrait-ambig.rs
+++ b/src/test/ui/traits/inheritance/repeated-supertrait-ambig.rs
@@ -31,7 +31,7 @@ fn with_trait<C:CompareToInts>(c: &C) -> bool {
 }
 
 fn with_ufcs1<C:CompareToInts>(c: &C) -> bool {
-    CompareToInts::same_as(c, 22) //~ ERROR `dyn CompareToInts: CompareTo<i32>` is not satisfied
+    <dyn CompareToInts>::same_as(c, 22) //~ ERROR `dyn CompareToInts: CompareTo<i32>` is not satisfi
 }
 
 fn with_ufcs2<C:CompareToInts>(c: &C) -> bool {
diff --git a/src/test/ui/traits/inheritance/repeated-supertrait-ambig.stderr b/src/test/ui/traits/inheritance/repeated-supertrait-ambig.stderr
index 5353b5e2260..bb11f18e545 100644
--- a/src/test/ui/traits/inheritance/repeated-supertrait-ambig.stderr
+++ b/src/test/ui/traits/inheritance/repeated-supertrait-ambig.stderr
@@ -21,8 +21,8 @@ error[E0277]: the trait bound `dyn CompareToInts: CompareTo<i32>` is not satisfi
 LL |     fn same_as(&self, t: T) -> bool;
    |     -------------------------------- required by `CompareTo::same_as`
 ...
-LL |     CompareToInts::same_as(c, 22)
-   |     ^^^^^^^^^^^^^^^^^^^^^^ the trait `CompareTo<i32>` is not implemented for `dyn CompareToInts`
+LL |     <dyn CompareToInts>::same_as(c, 22)
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `CompareTo<i32>` is not implemented for `dyn CompareToInts`
 
 error[E0277]: the trait bound `C: CompareTo<i32>` is not satisfied
   --> $DIR/repeated-supertrait-ambig.rs:38:5
diff --git a/src/test/ui/traits/inheritance/repeated-supertrait.rs b/src/test/ui/traits/inheritance/repeated-supertrait.rs
index 339f9c37eea..cb2581ffa99 100644
--- a/src/test/ui/traits/inheritance/repeated-supertrait.rs
+++ b/src/test/ui/traits/inheritance/repeated-supertrait.rs
@@ -31,7 +31,7 @@ fn with_trait<C:CompareToInts>(c: &C) -> bool {
 }
 
 fn with_ufcs1<C:CompareToInts>(c: &C) -> bool {
-    CompareToInts::same_as(c, 22_i64) && CompareToInts::same_as(c, 22_u64)
+    <dyn CompareToInts>::same_as(c, 22_i64) && <dyn CompareToInts>::same_as(c, 22_u64)
 }
 
 fn with_ufcs2<C:CompareToInts>(c: &C) -> bool {
diff --git a/src/test/ui/traits/item-privacy.rs b/src/test/ui/traits/item-privacy.rs
index 1ea1d65df62..38d06b967bc 100644
--- a/src/test/ui/traits/item-privacy.rs
+++ b/src/test/ui/traits/item-privacy.rs
@@ -81,8 +81,8 @@ fn check_method() {
     //~^ ERROR no function or associated item named `b` found
     S::c(&S); // OK
     // a, b, c are resolved as inherent items, their traits don't need to be in scope
-    C::a(&S); //~ ERROR associated function `a` is private
-    C::b(&S); // OK
+    <dyn C>::a(&S); //~ ERROR associated function `a` is private
+    <dyn C>::b(&S); // OK
     C::c(&S); // OK
 }
 
@@ -98,9 +98,9 @@ fn check_assoc_const() {
     S::B; //~ ERROR no associated item named `B` found
     S::C; // OK
     // A, B, C are resolved as inherent items, their traits don't need to be in scope
-    C::A; //~ ERROR associated constant `A` is private
-          //~^ ERROR the trait `assoc_const::C` cannot be made into an object
-    C::B; // ERROR the trait `assoc_const::C` cannot be made into an object
+    <dyn C>::A; //~ ERROR associated constant `A` is private
+                //~^ ERROR the trait `assoc_const::C` cannot be made into an object
+    <dyn C>::B; // ERROR the trait `assoc_const::C` cannot be made into an object
     C::C; // OK
 }
 
diff --git a/src/test/ui/traits/item-privacy.stderr b/src/test/ui/traits/item-privacy.stderr
index b7dad54a6d3..68d527dc786 100644
--- a/src/test/ui/traits/item-privacy.stderr
+++ b/src/test/ui/traits/item-privacy.stderr
@@ -67,10 +67,10 @@ LL | use method::B;
    |
 
 error[E0624]: associated function `a` is private
-  --> $DIR/item-privacy.rs:84:8
+  --> $DIR/item-privacy.rs:84:14
    |
-LL |     C::a(&S);
-   |        ^ private associated function
+LL |     <dyn C>::a(&S);
+   |              ^ private associated function
 
 error[E0599]: no associated item named `A` found for struct `S` in the current scope
   --> $DIR/item-privacy.rs:97:8
@@ -104,16 +104,16 @@ LL | use assoc_const::B;
    |
 
 error[E0624]: associated constant `A` is private
-  --> $DIR/item-privacy.rs:101:8
+  --> $DIR/item-privacy.rs:101:14
    |
-LL |     C::A;
-   |        ^ private associated constant
+LL |     <dyn C>::A;
+   |              ^ private associated constant
 
 error[E0038]: the trait `assoc_const::C` cannot be made into an object
-  --> $DIR/item-privacy.rs:101:5
+  --> $DIR/item-privacy.rs:101:6
    |
-LL |     C::A;
-   |     ^ `assoc_const::C` cannot be made into an object
+LL |     <dyn C>::A;
+   |      ^^^^^ `assoc_const::C` cannot be made into an object
    |
    = help: consider moving `C` to another trait
    = help: consider moving `B` to another trait
diff --git a/src/tools/clippy/clippy_lints/src/lifetimes.rs b/src/tools/clippy/clippy_lints/src/lifetimes.rs
index 33ff01a30e8..3ac6e6cbbef 100644
--- a/src/tools/clippy/clippy_lints/src/lifetimes.rs
+++ b/src/tools/clippy/clippy_lints/src/lifetimes.rs
@@ -387,7 +387,7 @@ impl<'a, 'tcx> Visitor<'tcx> for RefVisitor<'a, 'tcx> {
                 self.nested_elision_site_lts.append(&mut sub_visitor.all_lts());
                 return;
             },
-            TyKind::TraitObject(bounds, ref lt) => {
+            TyKind::TraitObject(bounds, ref lt, _) => {
                 if !lt.is_elided() {
                     self.unelided_trait_object_lifetime = true;
                 }
diff --git a/src/tools/clippy/clippy_lints/src/types/borrowed_box.rs b/src/tools/clippy/clippy_lints/src/types/borrowed_box.rs
index a7a511b21cf..81090040d92 100644
--- a/src/tools/clippy/clippy_lints/src/types/borrowed_box.rs
+++ b/src/tools/clippy/clippy_lints/src/types/borrowed_box.rs
@@ -50,7 +50,7 @@ pub(super) fn check(cx: &LateContext<'_>, hir_ty: &hir::Ty<'_>, lt: &Lifetime, m
                     // Originally reported as the issue #3128.
                     let inner_snippet = snippet(cx, inner.span, "..");
                     let suggestion = match &inner.kind {
-                        TyKind::TraitObject(bounds, lt_bound) if bounds.len() > 1 || !lt_bound.is_elided() => {
+                        TyKind::TraitObject(bounds, lt_bound, _) if bounds.len() > 1 || !lt_bound.is_elided() => {
                             format!("&{}({})", ltopt, &inner_snippet)
                         },
                         TyKind::Path(qpath)
@@ -86,7 +86,7 @@ pub(super) fn check(cx: &LateContext<'_>, hir_ty: &hir::Ty<'_>, lt: &Lifetime, m
 // Returns true if given type is `Any` trait.
 fn is_any_trait(t: &hir::Ty<'_>) -> bool {
     if_chain! {
-        if let TyKind::TraitObject(ref traits, _) = t.kind;
+        if let TyKind::TraitObject(ref traits, ..) = t.kind;
         if !traits.is_empty();
         // Only Send/Sync can be used as additional traits, so it is enough to
         // check only the first trait.
diff --git a/src/tools/clippy/clippy_lints/src/types/mod.rs b/src/tools/clippy/clippy_lints/src/types/mod.rs
index f7a6399a7f0..4a1a608e8ae 100644
--- a/src/tools/clippy/clippy_lints/src/types/mod.rs
+++ b/src/tools/clippy/clippy_lints/src/types/mod.rs
@@ -911,7 +911,7 @@ impl<'tcx> Visitor<'tcx> for TypeComplexityVisitor {
             // function types bring a lot of overhead
             TyKind::BareFn(ref bare) if bare.abi == Abi::Rust => (50 * self.nest, 1),
 
-            TyKind::TraitObject(ref param_bounds, _) => {
+            TyKind::TraitObject(ref param_bounds, ..) => {
                 let has_lifetime_parameters = param_bounds.iter().any(|bound| {
                     bound
                         .bound_generic_params
diff --git a/src/tools/clippy/clippy_utils/src/hir_utils.rs b/src/tools/clippy/clippy_utils/src/hir_utils.rs
index af82f992d56..7f7d9c5f56a 100644
--- a/src/tools/clippy/clippy_utils/src/hir_utils.rs
+++ b/src/tools/clippy/clippy_utils/src/hir_utils.rs
@@ -892,7 +892,7 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
             TyKind::OpaqueDef(_, arg_list) => {
                 self.hash_generic_args(arg_list);
             },
-            TyKind::TraitObject(_, lifetime) => {
+            TyKind::TraitObject(_, lifetime, _) => {
                 self.hash_lifetime(lifetime);
             },
             TyKind::Typeof(anon_const) => {