diff --git a/compiler/rustc_borrowck/src/region_infer/mod.rs b/compiler/rustc_borrowck/src/region_infer/mod.rs
index 2ae13990a4589..70124dba80951 100644
--- a/compiler/rustc_borrowck/src/region_infer/mod.rs
+++ b/compiler/rustc_borrowck/src/region_infer/mod.rs
@@ -17,7 +17,7 @@ use rustc_middle::mir::{
 };
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::traits::ObligationCauseCode;
-use rustc_middle::ty::{self, RegionVid, Ty, TyCtxt, TypeFoldable, TypeVisitable};
+use rustc_middle::ty::{self, RegionVid, Ty, TyCtxt, TypeFoldable};
 use rustc_span::Span;
 
 use crate::{
diff --git a/compiler/rustc_codegen_cranelift/src/lib.rs b/compiler/rustc_codegen_cranelift/src/lib.rs
index d3868730557b7..c7fe382bac4e3 100644
--- a/compiler/rustc_codegen_cranelift/src/lib.rs
+++ b/compiler/rustc_codegen_cranelift/src/lib.rs
@@ -86,7 +86,7 @@ mod prelude {
     pub(crate) use rustc_middle::ty::layout::{self, LayoutOf, TyAndLayout};
     pub(crate) use rustc_middle::ty::{
         self, FloatTy, Instance, InstanceDef, IntTy, ParamEnv, Ty, TyCtxt, TypeAndMut,
-        TypeFoldable, TypeVisitable, UintTy,
+        TypeFoldable, UintTy,
     };
     pub(crate) use rustc_target::abi::{Abi, Scalar, Size, VariantIdx};
 
diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs
index bb265b8289ed9..de1734332d448 100644
--- a/compiler/rustc_codegen_ssa/src/mir/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs
@@ -3,7 +3,7 @@ use crate::traits::*;
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::ErrorHandled;
 use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, TyAndLayout};
-use rustc_middle::ty::{self, Instance, Ty, TypeFoldable, TypeVisitable};
+use rustc_middle::ty::{self, Instance, Ty, TypeFoldable};
 use rustc_target::abi::call::{FnAbi, PassMode};
 
 use std::iter;
diff --git a/compiler/rustc_const_eval/src/interpret/util.rs b/compiler/rustc_const_eval/src/interpret/util.rs
index cabc65e2c077e..59c4b92c0e81b 100644
--- a/compiler/rustc_const_eval/src/interpret/util.rs
+++ b/compiler/rustc_const_eval/src/interpret/util.rs
@@ -1,5 +1,5 @@
 use rustc_middle::mir::interpret::InterpResult;
-use rustc_middle::ty::{self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor};
+use rustc_middle::ty::{self, ir::TypeVisitor, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable};
 use std::ops::ControlFlow;
 
 /// Checks whether a type contains generic parameters which require substitution.
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index 5e3601efbbe8e..00dea77bad9c0 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -261,7 +261,7 @@ pub(super) fn check_opaque_for_inheriting_lifetimes(
         selftys: Vec<(Span, Option<String>)>,
     }
 
-    impl<'tcx> ty::visit::TypeVisitor<'tcx> for ProhibitOpaqueVisitor<'tcx> {
+    impl<'tcx> ty::visit::ir::TypeVisitor<'tcx> for ProhibitOpaqueVisitor<'tcx> {
         type BreakTy = Ty<'tcx>;
 
         fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
@@ -1447,7 +1447,7 @@ fn opaque_type_cycle_error(
                     opaques: Vec<DefId>,
                     closures: Vec<DefId>,
                 }
-                impl<'tcx> ty::visit::TypeVisitor<'tcx> for OpaqueTypeCollector {
+                impl<'tcx> ty::visit::ir::TypeVisitor<'tcx> for OpaqueTypeCollector {
                     fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
                         match *t.kind() {
                             ty::Alias(ty::Opaque, ty::AliasTy { def_id: def, .. }) => {
diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
index c86af6a379bfa..cdc3216e26c74 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
@@ -16,7 +16,7 @@ use rustc_infer::traits::util;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
 use rustc_middle::ty::util::ExplicitSelf;
 use rustc_middle::ty::{
-    self, DefIdTree, InternalSubsts, Ty, TypeFoldable, TypeFolder, TypeSuperFoldable, TypeVisitable,
+    self, ir::TypeFolder, DefIdTree, InternalSubsts, Ty, TypeFoldable, TypeSuperFoldable,
 };
 use rustc_middle::ty::{GenericParamDefKind, ToPredicate, TyCtxt};
 use rustc_span::Span;
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index 5f95622883b8f..3ad7e4f130b63 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -16,8 +16,8 @@ use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::trait_def::TraitSpecializationKind;
 use rustc_middle::ty::{
-    self, AdtKind, DefIdTree, GenericParamDefKind, Ty, TyCtxt, TypeFoldable, TypeSuperVisitable,
-    TypeVisitable, TypeVisitor,
+    self, ir::TypeVisitor, AdtKind, DefIdTree, GenericParamDefKind, Ty, TyCtxt, TypeFoldable,
+    TypeSuperVisitable,
 };
 use rustc_middle::ty::{GenericArgKind, InternalSubsts};
 use rustc_session::parse::feature_err;
@@ -1435,7 +1435,7 @@ fn check_where_clauses<'tcx>(wfcx: &WfCheckingCtxt<'_, 'tcx>, span: Span, def_id
             struct CountParams {
                 params: FxHashSet<u32>,
             }
-            impl<'tcx> ty::visit::TypeVisitor<'tcx> for CountParams {
+            impl<'tcx> ty::visit::ir::TypeVisitor<'tcx> for CountParams {
                 type BreakTy = ();
 
                 fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
diff --git a/compiler/rustc_hir_analysis/src/coherence/orphan.rs b/compiler/rustc_hir_analysis/src/coherence/orphan.rs
index 7d381d8902ac2..a4f7bd9351371 100644
--- a/compiler/rustc_hir_analysis/src/coherence/orphan.rs
+++ b/compiler/rustc_hir_analysis/src/coherence/orphan.rs
@@ -8,7 +8,7 @@ use rustc_hir as hir;
 use rustc_middle::ty::subst::InternalSubsts;
 use rustc_middle::ty::util::IgnoreRegions;
 use rustc_middle::ty::{
-    self, AliasKind, ImplPolarity, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor,
+    self, ir::TypeVisitor, AliasKind, ImplPolarity, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable,
 };
 use rustc_session::lint;
 use rustc_span::def_id::{DefId, LocalDefId};
diff --git a/compiler/rustc_hir_analysis/src/collect/lifetimes.rs b/compiler/rustc_hir_analysis/src/collect/lifetimes.rs
index 3c67722b637bf..4d296c845f479 100644
--- a/compiler/rustc_hir_analysis/src/collect/lifetimes.rs
+++ b/compiler/rustc_hir_analysis/src/collect/lifetimes.rs
@@ -17,7 +17,7 @@ use rustc_hir::{GenericArg, GenericParam, GenericParamKind, HirIdMap, LifetimeNa
 use rustc_middle::bug;
 use rustc_middle::hir::nested_filter;
 use rustc_middle::middle::resolve_lifetime::*;
-use rustc_middle::ty::{self, DefIdTree, TyCtxt, TypeSuperVisitable, TypeVisitor};
+use rustc_middle::ty::{self, ir::TypeVisitor, DefIdTree, TyCtxt, TypeSuperVisitable};
 use rustc_span::def_id::DefId;
 use rustc_span::symbol::{sym, Ident};
 use rustc_span::Span;
diff --git a/compiler/rustc_hir_analysis/src/collect/type_of.rs b/compiler/rustc_hir_analysis/src/collect/type_of.rs
index c5522c94874dd..5741d9db31d49 100644
--- a/compiler/rustc_hir_analysis/src/collect/type_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/type_of.rs
@@ -9,7 +9,7 @@ use rustc_middle::ty::print::with_forced_trimmed_paths;
 use rustc_middle::ty::subst::InternalSubsts;
 use rustc_middle::ty::util::IntTypeExt;
 use rustc_middle::ty::{
-    self, DefIdTree, IsSuggestable, Ty, TyCtxt, TypeFolder, TypeSuperFoldable, TypeVisitable,
+    self, ir::TypeFolder, DefIdTree, IsSuggestable, Ty, TyCtxt, TypeSuperFoldable, TypeVisitable,
 };
 use rustc_span::symbol::Ident;
 use rustc_span::{Span, DUMMY_SP};
diff --git a/compiler/rustc_hir_analysis/src/constrained_generic_params.rs b/compiler/rustc_hir_analysis/src/constrained_generic_params.rs
index 56cc1d8fadc00..e5509318283c5 100644
--- a/compiler/rustc_hir_analysis/src/constrained_generic_params.rs
+++ b/compiler/rustc_hir_analysis/src/constrained_generic_params.rs
@@ -1,5 +1,5 @@
 use rustc_data_structures::fx::FxHashSet;
-use rustc_middle::ty::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
+use rustc_middle::ty::visit::{ir::TypeVisitor, TypeSuperVisitable, TypeVisitable};
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::source_map::Span;
 use std::ops::ControlFlow;
diff --git a/compiler/rustc_hir_analysis/src/hir_wf_check.rs b/compiler/rustc_hir_analysis/src/hir_wf_check.rs
index 9cf82b39ec947..cb9499712e45b 100644
--- a/compiler/rustc_hir_analysis/src/hir_wf_check.rs
+++ b/compiler/rustc_hir_analysis/src/hir_wf_check.rs
@@ -5,7 +5,7 @@ use rustc_hir::{ForeignItem, ForeignItemKind};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_infer::traits::{ObligationCause, WellFormedLoc};
 use rustc_middle::ty::query::Providers;
-use rustc_middle::ty::{self, Region, TyCtxt, TypeFoldable, TypeFolder};
+use rustc_middle::ty::{self, ir::TypeFolder, Region, TyCtxt, TypeFoldable};
 use rustc_span::def_id::LocalDefId;
 use rustc_trait_selection::traits;
 
diff --git a/compiler/rustc_hir_analysis/src/variance/mod.rs b/compiler/rustc_hir_analysis/src/variance/mod.rs
index 079070be27983..981bf87db0f46 100644
--- a/compiler/rustc_hir_analysis/src/variance/mod.rs
+++ b/compiler/rustc_hir_analysis/src/variance/mod.rs
@@ -99,7 +99,7 @@ fn variance_of_opaque(tcx: TyCtxt<'_>, item_def_id: LocalDefId) -> &[ty::Varianc
         }
     }
 
-    impl<'tcx> ty::TypeVisitor<'tcx> for OpaqueTypeLifetimeCollector<'tcx> {
+    impl<'tcx> ty::ir::TypeVisitor<'tcx> for OpaqueTypeLifetimeCollector<'tcx> {
         #[instrument(level = "trace", skip(self), ret)]
         fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
             if let ty::RegionKind::ReEarlyBound(ebr) = r.kind() {
diff --git a/compiler/rustc_hir_typeck/src/closure.rs b/compiler/rustc_hir_typeck/src/closure.rs
index 211fe477a2d8d..c0e4440ef3ad6 100644
--- a/compiler/rustc_hir_typeck/src/closure.rs
+++ b/compiler/rustc_hir_typeck/src/closure.rs
@@ -12,7 +12,7 @@ use rustc_infer::infer::{InferOk, InferResult};
 use rustc_macros::{TypeFoldable, TypeVisitable};
 use rustc_middle::ty::subst::InternalSubsts;
 use rustc_middle::ty::visit::TypeVisitable;
-use rustc_middle::ty::{self, Ty, TypeSuperVisitable, TypeVisitor};
+use rustc_middle::ty::{self, ir::TypeVisitor, Ty, TypeSuperVisitable};
 use rustc_span::def_id::LocalDefId;
 use rustc_span::source_map::Span;
 use rustc_span::sym;
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs
index b220a87bc658a..c8ee8fc698f7b 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs
@@ -3,7 +3,7 @@ use rustc_hir as hir;
 use rustc_hir::def::Res;
 use rustc_hir::def_id::DefId;
 use rustc_infer::traits::ObligationCauseCode;
-use rustc_middle::ty::{self, DefIdTree, Ty, TypeSuperVisitable, TypeVisitable, TypeVisitor};
+use rustc_middle::ty::{self, ir::TypeVisitor, DefIdTree, Ty, TypeSuperVisitable, TypeVisitable};
 use rustc_span::{self, Span};
 use rustc_trait_selection::traits;
 
diff --git a/compiler/rustc_hir_typeck/src/mem_categorization.rs b/compiler/rustc_hir_typeck/src/mem_categorization.rs
index 92240b66eb1d4..60e0ce3494d43 100644
--- a/compiler/rustc_hir_typeck/src/mem_categorization.rs
+++ b/compiler/rustc_hir_typeck/src/mem_categorization.rs
@@ -51,7 +51,6 @@
 use rustc_middle::hir::place::*;
 use rustc_middle::ty::adjustment;
 use rustc_middle::ty::fold::TypeFoldable;
-use rustc_middle::ty::visit::TypeVisitable;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 
 use rustc_data_structures::fx::FxIndexMap;
diff --git a/compiler/rustc_hir_typeck/src/method/probe.rs b/compiler/rustc_hir_typeck/src/method/probe.rs
index 16b0d48002efc..b5e6727bfbadf 100644
--- a/compiler/rustc_hir_typeck/src/method/probe.rs
+++ b/compiler/rustc_hir_typeck/src/method/probe.rs
@@ -20,7 +20,7 @@ use rustc_middle::ty::fast_reject::{simplify_type, TreatParams};
 use rustc_middle::ty::AssocItem;
 use rustc_middle::ty::GenericParamDefKind;
 use rustc_middle::ty::ToPredicate;
-use rustc_middle::ty::{self, ParamEnvAnd, Ty, TyCtxt, TypeFoldable, TypeVisitable};
+use rustc_middle::ty::{self, ParamEnvAnd, Ty, TyCtxt, TypeFoldable};
 use rustc_middle::ty::{InternalSubsts, SubstsRef};
 use rustc_session::lint;
 use rustc_span::def_id::DefId;
diff --git a/compiler/rustc_hir_typeck/src/op.rs b/compiler/rustc_hir_typeck/src/op.rs
index ba72aefe39c16..ffaf58cd7b67b 100644
--- a/compiler/rustc_hir_typeck/src/op.rs
+++ b/compiler/rustc_hir_typeck/src/op.rs
@@ -13,7 +13,7 @@ use rustc_middle::ty::adjustment::{
 };
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::{
-    self, DefIdTree, IsSuggestable, Ty, TyCtxt, TypeFolder, TypeSuperFoldable, TypeVisitable,
+    self, ir::TypeFolder, DefIdTree, IsSuggestable, Ty, TyCtxt, TypeSuperFoldable, TypeVisitable,
 };
 use rustc_session::errors::ExprParenthesesNeeded;
 use rustc_span::source_map::Spanned;
diff --git a/compiler/rustc_hir_typeck/src/writeback.rs b/compiler/rustc_hir_typeck/src/writeback.rs
index 0aa34f9dd7072..f0ce5c28dd4a9 100644
--- a/compiler/rustc_hir_typeck/src/writeback.rs
+++ b/compiler/rustc_hir_typeck/src/writeback.rs
@@ -13,8 +13,8 @@ use rustc_infer::infer::InferCtxt;
 use rustc_middle::hir::place::Place as HirPlace;
 use rustc_middle::mir::FakeReadCause;
 use rustc_middle::ty::adjustment::{Adjust, Adjustment, PointerCast};
-use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
-use rustc_middle::ty::visit::{TypeSuperVisitable, TypeVisitable};
+use rustc_middle::ty::fold::{ir::TypeFolder, TypeFoldable, TypeSuperFoldable};
+use rustc_middle::ty::visit::TypeSuperVisitable;
 use rustc_middle::ty::TypeckResults;
 use rustc_middle::ty::{self, ClosureSizeProfileData, Ty, TyCtxt};
 use rustc_span::symbol::sym;
@@ -561,7 +561,7 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
             struct RecursionChecker {
                 def_id: LocalDefId,
             }
-            impl<'tcx> ty::TypeVisitor<'tcx> for RecursionChecker {
+            impl<'tcx> ty::ir::TypeVisitor<'tcx> for RecursionChecker {
                 type BreakTy = ();
                 fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
                     if let ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }) = *t.kind() {
diff --git a/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs b/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
index c11dcc8587b5d..b0d1d158a3c58 100644
--- a/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
+++ b/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
@@ -10,7 +10,7 @@ use crate::infer::canonical::{
 };
 use crate::infer::InferCtxt;
 use rustc_middle::ty::flags::FlagComputation;
-use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
+use rustc_middle::ty::fold::{ir::TypeFolder, TypeFoldable, TypeSuperFoldable};
 use rustc_middle::ty::subst::GenericArg;
 use rustc_middle::ty::{self, BoundVar, InferConst, List, Ty, TyCtxt, TypeFlags};
 use std::sync::atomic::Ordering;
diff --git a/compiler/rustc_infer/src/infer/combine.rs b/compiler/rustc_infer/src/infer/combine.rs
index 4da2a67414498..b1dfc23f02ec5 100644
--- a/compiler/rustc_infer/src/infer/combine.rs
+++ b/compiler/rustc_infer/src/infer/combine.rs
@@ -38,8 +38,8 @@ use rustc_middle::ty::error::{ExpectedFound, TypeError};
 use rustc_middle::ty::relate::{self, Relate, RelateResult, TypeRelation};
 use rustc_middle::ty::subst::SubstsRef;
 use rustc_middle::ty::{
-    self, AliasKind, FallibleTypeFolder, InferConst, ToPredicate, Ty, TyCtxt, TypeFoldable,
-    TypeSuperFoldable, TypeVisitable,
+    self, ir::FallibleTypeFolder, AliasKind, InferConst, ToPredicate, Ty, TyCtxt, TypeFoldable,
+    TypeSuperFoldable,
 };
 use rustc_middle::ty::{IntType, UintType};
 use rustc_span::{Span, DUMMY_SP};
diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
index 88a0d6def5ec2..083af0e570f25 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
@@ -1491,7 +1491,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             }
         }
 
-        impl<'tcx> ty::visit::TypeVisitor<'tcx> for OpaqueTypesVisitor<'tcx> {
+        impl<'tcx> ty::visit::ir::TypeVisitor<'tcx> for OpaqueTypesVisitor<'tcx> {
             fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
                 if let Some((kind, def_id)) = TyCategory::from_ty(self.tcx, t) {
                     let span = self.tcx.def_span(def_id);
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 6a463583dfb0f..e444485426e20 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
@@ -17,7 +17,8 @@ use rustc_hir::{
     TyKind,
 };
 use rustc_middle::ty::{
-    self, AssocItemContainer, StaticLifetimeVisitor, Ty, TyCtxt, TypeSuperVisitable, TypeVisitor,
+    self, ir::TypeVisitor, AssocItemContainer, StaticLifetimeVisitor, Ty, TyCtxt,
+    TypeSuperVisitable,
 };
 use rustc_span::symbol::Ident;
 use rustc_span::Span;
diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs
index 40c0c806e1ff8..4d6bd6e8e4bea 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs
@@ -75,7 +75,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
             }
         }
 
-        impl<'tcx> ty::visit::TypeVisitor<'tcx> for HighlightBuilder<'tcx> {
+        impl<'tcx> ty::visit::ir::TypeVisitor<'tcx> for HighlightBuilder<'tcx> {
             fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
                 if !r.has_name() && self.counter <= 3 {
                     self.highlight.highlighting_region(r, self.counter);
diff --git a/compiler/rustc_infer/src/infer/freshen.rs b/compiler/rustc_infer/src/infer/freshen.rs
index 073a2b0753dc4..37da037f91657 100644
--- a/compiler/rustc_infer/src/infer/freshen.rs
+++ b/compiler/rustc_infer/src/infer/freshen.rs
@@ -33,8 +33,8 @@
 use super::InferCtxt;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_middle::infer::unify_key::ToType;
-use rustc_middle::ty::fold::TypeFolder;
-use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable, TypeVisitable};
+use rustc_middle::ty::fold::ir::TypeFolder;
+use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable};
 use std::collections::hash_map::Entry;
 
 pub struct TypeFreshener<'a, 'tcx> {
diff --git a/compiler/rustc_infer/src/infer/fudge.rs b/compiler/rustc_infer/src/infer/fudge.rs
index 6dd6c4e1f5ee8..aa126814fb5b5 100644
--- a/compiler/rustc_infer/src/infer/fudge.rs
+++ b/compiler/rustc_infer/src/infer/fudge.rs
@@ -1,4 +1,4 @@
-use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
+use rustc_middle::ty::fold::{ir::TypeFolder, TypeFoldable, TypeSuperFoldable};
 use rustc_middle::ty::{self, ConstVid, FloatVid, IntVid, RegionVid, Ty, TyCtxt, TyVid};
 
 use super::type_variable::TypeVariableOrigin;
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index ae196a7133cae..6a178801306d5 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -26,7 +26,7 @@ use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::traits::select;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
 use rustc_middle::ty::fold::BoundVarReplacerDelegate;
-use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
+use rustc_middle::ty::fold::{ir::TypeFolder, TypeFoldable, TypeSuperFoldable};
 use rustc_middle::ty::relate::RelateResult;
 use rustc_middle::ty::subst::{GenericArg, GenericArgKind, InternalSubsts, SubstsRef};
 use rustc_middle::ty::visit::TypeVisitable;
diff --git a/compiler/rustc_infer/src/infer/nll_relate/mod.rs b/compiler/rustc_infer/src/infer/nll_relate/mod.rs
index 1dd5062acaf05..696cc5f35c950 100644
--- a/compiler/rustc_infer/src/infer/nll_relate/mod.rs
+++ b/compiler/rustc_infer/src/infer/nll_relate/mod.rs
@@ -29,7 +29,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::relate::{self, Relate, RelateResult, TypeRelation};
-use rustc_middle::ty::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
+use rustc_middle::ty::visit::{ir::TypeVisitor, TypeSuperVisitable, TypeVisitable};
 use rustc_middle::ty::{self, InferConst, Ty, TyCtxt};
 use rustc_span::Span;
 use std::fmt::Debug;
diff --git a/compiler/rustc_infer/src/infer/opaque_types.rs b/compiler/rustc_infer/src/infer/opaque_types.rs
index b68b0baaa4062..4105a180eb3ba 100644
--- a/compiler/rustc_infer/src/infer/opaque_types.rs
+++ b/compiler/rustc_infer/src/infer/opaque_types.rs
@@ -12,8 +12,8 @@ use rustc_middle::ty::error::{ExpectedFound, TypeError};
 use rustc_middle::ty::fold::BottomUpFolder;
 use rustc_middle::ty::GenericArgKind;
 use rustc_middle::ty::{
-    self, OpaqueHiddenType, OpaqueTypeKey, Ty, TyCtxt, TypeFoldable, TypeSuperVisitable,
-    TypeVisitable, TypeVisitor,
+    self, ir::TypeVisitor, OpaqueHiddenType, OpaqueTypeKey, Ty, TyCtxt, TypeFoldable,
+    TypeSuperVisitable, TypeVisitable,
 };
 use rustc_span::Span;
 
diff --git a/compiler/rustc_infer/src/infer/resolve.rs b/compiler/rustc_infer/src/infer/resolve.rs
index a39a40cf9abe2..1011306b7edfd 100644
--- a/compiler/rustc_infer/src/infer/resolve.rs
+++ b/compiler/rustc_infer/src/infer/resolve.rs
@@ -1,9 +1,12 @@
 use super::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use super::{FixupError, FixupResult, InferCtxt, Span};
 use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
-use rustc_middle::ty::fold::{FallibleTypeFolder, TypeFolder, TypeSuperFoldable};
-use rustc_middle::ty::visit::{TypeSuperVisitable, TypeVisitor};
-use rustc_middle::ty::{self, Const, InferConst, Ty, TyCtxt, TypeFoldable, TypeVisitable};
+use rustc_middle::ty::fold::{
+    ir::{FallibleTypeFolder, TypeFolder},
+    TypeSuperFoldable,
+};
+use rustc_middle::ty::visit::{ir::TypeVisitor, TypeSuperVisitable};
+use rustc_middle::ty::{self, Const, InferConst, Ty, TyCtxt, TypeFoldable};
 
 use std::ops::ControlFlow;
 
diff --git a/compiler/rustc_infer/src/traits/structural_impls.rs b/compiler/rustc_infer/src/traits/structural_impls.rs
index 1c6ab6a082b99..f0187e8541ef2 100644
--- a/compiler/rustc_infer/src/traits/structural_impls.rs
+++ b/compiler/rustc_infer/src/traits/structural_impls.rs
@@ -1,8 +1,8 @@
 use crate::traits;
 use crate::traits::project::Normalized;
-use rustc_middle::ty;
 use rustc_middle::ty::fold::{FallibleTypeFolder, TypeFoldable};
 use rustc_middle::ty::visit::{TypeVisitable, TypeVisitor};
+use rustc_middle::ty::{self, ir};
 
 use std::fmt;
 use std::ops::ControlFlow;
@@ -61,7 +61,7 @@ impl<'tcx> fmt::Debug for traits::MismatchedProjectionTypes<'tcx> {
 ///////////////////////////////////////////////////////////////////////////
 // TypeFoldable implementations.
 
-impl<'tcx, O: TypeFoldable<'tcx>> TypeFoldable<'tcx> for traits::Obligation<'tcx, O> {
+impl<'tcx, O: TypeFoldable<'tcx>> ir::TypeFoldable<'tcx> for traits::Obligation<'tcx, O> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         Ok(traits::Obligation {
             cause: self.cause,
@@ -72,7 +72,7 @@ impl<'tcx, O: TypeFoldable<'tcx>> TypeFoldable<'tcx> for traits::Obligation<'tcx
     }
 }
 
-impl<'tcx, O: TypeVisitable<'tcx>> TypeVisitable<'tcx> for traits::Obligation<'tcx, O> {
+impl<'tcx, O: TypeVisitable<'tcx>> ir::TypeVisitable<'tcx> for traits::Obligation<'tcx, O> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         self.predicate.visit_with(visitor)?;
         self.param_env.visit_with(visitor)
diff --git a/compiler/rustc_lint/src/types.rs b/compiler/rustc_lint/src/types.rs
index b0a5d3674ad27..997f22c0b6727 100644
--- a/compiler/rustc_lint/src/types.rs
+++ b/compiler/rustc_lint/src/types.rs
@@ -1144,7 +1144,7 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
 
     fn check_for_opaque_ty(&mut self, sp: Span, ty: Ty<'tcx>) -> bool {
         struct ProhibitOpaqueTypes;
-        impl<'tcx> ty::visit::TypeVisitor<'tcx> for ProhibitOpaqueTypes {
+        impl<'tcx> ty::visit::ir::TypeVisitor<'tcx> for ProhibitOpaqueTypes {
             type BreakTy = Ty<'tcx>;
 
             fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
diff --git a/compiler/rustc_macros/src/type_foldable.rs b/compiler/rustc_macros/src/type_foldable.rs
index 23e619221aab7..257b353e17c30 100644
--- a/compiler/rustc_macros/src/type_foldable.rs
+++ b/compiler/rustc_macros/src/type_foldable.rs
@@ -17,13 +17,13 @@ pub fn type_foldable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::
         vi.construct(|_, index| {
             let bind = &bindings[index];
             quote! {
-                ::rustc_middle::ty::fold::TypeFoldable::try_fold_with(#bind, __folder)?
+                ::rustc_middle::ty::fold::ir::TypeFoldable::try_fold_with(#bind, __folder)?
             }
         })
     });
 
     s.bound_impl(
-        quote!(::rustc_middle::ty::fold::TypeFoldable<'tcx>),
+        quote!(::rustc_middle::ty::fold::ir::TypeFoldable<'tcx>),
         quote! {
             fn try_fold_with<__F: ::rustc_middle::ty::fold::FallibleTypeFolder<'tcx>>(
                 self,
diff --git a/compiler/rustc_macros/src/type_visitable.rs b/compiler/rustc_macros/src/type_visitable.rs
index 1f95661ce9d5f..d164dd3cb98e5 100644
--- a/compiler/rustc_macros/src/type_visitable.rs
+++ b/compiler/rustc_macros/src/type_visitable.rs
@@ -13,13 +13,13 @@ pub fn type_visitable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2:
     s.add_bounds(synstructure::AddBounds::Generics);
     let body_visit = s.each(|bind| {
         quote! {
-            ::rustc_middle::ty::visit::TypeVisitable::visit_with(#bind, __visitor)?;
+            ::rustc_middle::ty::visit::ir::TypeVisitable::visit_with(#bind, __visitor)?;
         }
     });
     s.bind_with(|_| synstructure::BindStyle::Move);
 
     s.bound_impl(
-        quote!(::rustc_middle::ty::visit::TypeVisitable<'tcx>),
+        quote!(::rustc_middle::ty::visit::ir::TypeVisitable<'tcx>),
         quote! {
             fn visit_with<__V: ::rustc_middle::ty::visit::TypeVisitor<'tcx>>(
                 &self,
diff --git a/compiler/rustc_middle/src/infer/canonical.rs b/compiler/rustc_middle/src/infer/canonical.rs
index e6e4545d9c3fb..c6d67342cadff 100644
--- a/compiler/rustc_middle/src/infer/canonical.rs
+++ b/compiler/rustc_middle/src/infer/canonical.rs
@@ -42,7 +42,7 @@ pub struct Canonical<'tcx, V> {
 
 pub type CanonicalVarInfos<'tcx> = &'tcx List<CanonicalVarInfo<'tcx>>;
 
-impl<'tcx> ty::TypeFoldable<'tcx> for CanonicalVarInfos<'tcx> {
+impl<'tcx> ty::ir::TypeFoldable<'tcx> for CanonicalVarInfos<'tcx> {
     fn try_fold_with<F: ty::FallibleTypeFolder<'tcx>>(
         self,
         folder: &mut F,
diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs
index 56df1a66f9d29..ea57f7079f99e 100644
--- a/compiler/rustc_middle/src/lib.rs
+++ b/compiler/rustc_middle/src/lib.rs
@@ -60,6 +60,7 @@
 #![feature(yeet_expr)]
 #![feature(result_option_inspect)]
 #![feature(const_option)]
+#![feature(trait_alias)]
 #![recursion_limit = "512"]
 #![allow(rustc::potential_query_instability)]
 
diff --git a/compiler/rustc_middle/src/macros.rs b/compiler/rustc_middle/src/macros.rs
index 250f3d0797eb5..3e387d89d5f9f 100644
--- a/compiler/rustc_middle/src/macros.rs
+++ b/compiler/rustc_middle/src/macros.rs
@@ -69,7 +69,7 @@ macro_rules! CloneLiftImpls {
 macro_rules! TrivialTypeTraversalImpls {
     (for <$tcx:lifetime> { $($ty:ty,)+ }) => {
         $(
-            impl<$tcx> $crate::ty::fold::TypeFoldable<$tcx> for $ty {
+            impl<$tcx> $crate::ty::fold::ir::TypeFoldable<$tcx> for $ty {
                 fn try_fold_with<F: $crate::ty::fold::FallibleTypeFolder<$tcx>>(
                     self,
                     _: &mut F,
@@ -86,7 +86,7 @@ macro_rules! TrivialTypeTraversalImpls {
                 }
             }
 
-            impl<$tcx> $crate::ty::visit::TypeVisitable<$tcx> for $ty {
+            impl<$tcx> $crate::ty::visit::ir::TypeVisitable<$tcx> for $ty {
                 #[inline]
                 fn visit_with<F: $crate::ty::visit::TypeVisitor<$tcx>>(
                     &self,
@@ -121,7 +121,7 @@ macro_rules! EnumTypeTraversalImpl {
     (impl<$($p:tt),*> TypeFoldable<$tcx:tt> for $s:path {
         $($variants:tt)*
     } $(where $($wc:tt)*)*) => {
-        impl<$($p),*> $crate::ty::fold::TypeFoldable<$tcx> for $s
+        impl<$($p),*> $crate::ty::fold::ir::TypeFoldable<$tcx> for $s
             $(where $($wc)*)*
         {
             fn try_fold_with<V: $crate::ty::fold::FallibleTypeFolder<$tcx>>(
@@ -136,7 +136,7 @@ macro_rules! EnumTypeTraversalImpl {
     (impl<$($p:tt),*> TypeVisitable<$tcx:tt> for $s:path {
         $($variants:tt)*
     } $(where $($wc:tt)*)*) => {
-        impl<$($p),*> $crate::ty::visit::TypeVisitable<$tcx> for $s
+        impl<$($p),*> $crate::ty::visit::ir::TypeVisitable<$tcx> for $s
             $(where $($wc)*)*
         {
             fn visit_with<V: $crate::ty::visit::TypeVisitor<$tcx>>(
@@ -163,7 +163,7 @@ macro_rules! EnumTypeTraversalImpl {
                 output(
                     $variant ( $($variant_arg),* ) => {
                         $variant (
-                            $($crate::ty::fold::TypeFoldable::try_fold_with($variant_arg, $folder)?),*
+                            $($crate::ty::fold::ir::TypeFoldable::try_fold_with($variant_arg, $folder)?),*
                         )
                     }
                     $($output)*
@@ -180,7 +180,7 @@ macro_rules! EnumTypeTraversalImpl {
                 output(
                     $variant { $($variant_arg),* } => {
                         $variant {
-                            $($variant_arg: $crate::ty::fold::TypeFoldable::fold_with(
+                            $($variant_arg: $crate::ty::fold::ir::TypeFoldable::fold_with(
                                 $variant_arg, $folder
                             )?),* }
                     }
@@ -216,7 +216,7 @@ macro_rules! EnumTypeTraversalImpl {
                 input($($input)*)
                 output(
                     $variant ( $($variant_arg),* ) => {
-                        $($crate::ty::visit::TypeVisitable::visit_with(
+                        $($crate::ty::visit::ir::TypeVisitable::visit_with(
                             $variant_arg, $visitor
                         )?;)*
                         ::std::ops::ControlFlow::Continue(())
@@ -234,7 +234,7 @@ macro_rules! EnumTypeTraversalImpl {
                 input($($input)*)
                 output(
                     $variant { $($variant_arg),* } => {
-                        $($crate::ty::visit::TypeVisitable::visit_with(
+                        $($crate::ty::visit::ir::TypeVisitable::visit_with(
                             $variant_arg, $visitor
                         )?;)*
                         ::std::ops::ControlFlow::Continue(())
diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs
index 10ac7e0d39af6..1955866cb43ca 100644
--- a/compiler/rustc_middle/src/mir/mod.rs
+++ b/compiler/rustc_middle/src/mir/mod.rs
@@ -7,10 +7,10 @@ use crate::mir::interpret::{
 };
 use crate::mir::visit::MirVisitable;
 use crate::ty::codec::{TyDecoder, TyEncoder};
-use crate::ty::fold::{FallibleTypeFolder, TypeFoldable};
+use crate::ty::fold::{ir::TypeFoldable, FallibleTypeFolder};
 use crate::ty::print::{FmtPrinter, Printer};
 use crate::ty::visit::{TypeVisitable, TypeVisitor};
-use crate::ty::{self, DefIdTree, List, Ty, TyCtxt};
+use crate::ty::{self, ir, DefIdTree, List, Ty, TyCtxt};
 use crate::ty::{AdtDef, InstanceDef, ScalarInt, UserTypeAnnotationIndex};
 use crate::ty::{GenericArg, InternalSubsts, SubstsRef};
 
@@ -2751,7 +2751,7 @@ impl<'tcx> TypeFoldable<'tcx> for UserTypeProjection {
     }
 }
 
-impl<'tcx> TypeVisitable<'tcx> for UserTypeProjection {
+impl<'tcx> ir::TypeVisitable<'tcx> for UserTypeProjection {
     fn visit_with<Vs: TypeVisitor<'tcx>>(&self, visitor: &mut Vs) -> ControlFlow<Vs::BreakTy> {
         self.base.visit_with(visitor)
         // Note: there's nothing in `self.proj` to visit.
diff --git a/compiler/rustc_middle/src/mir/type_visitable.rs b/compiler/rustc_middle/src/mir/type_visitable.rs
index d44c6809bd830..4b6c4d57c626a 100644
--- a/compiler/rustc_middle/src/mir/type_visitable.rs
+++ b/compiler/rustc_middle/src/mir/type_visitable.rs
@@ -2,7 +2,7 @@
 
 use super::*;
 
-impl<'tcx, R: Idx, C: Idx> TypeVisitable<'tcx> for BitMatrix<R, C> {
+impl<'tcx, R: Idx, C: Idx> ir::TypeVisitable<'tcx> for BitMatrix<R, C> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> ControlFlow<V::BreakTy> {
         ControlFlow::Continue(())
     }
diff --git a/compiler/rustc_middle/src/traits/solve.rs b/compiler/rustc_middle/src/traits/solve.rs
index 63f9c32f0a74b..df2fe5f03c81f 100644
--- a/compiler/rustc_middle/src/traits/solve.rs
+++ b/compiler/rustc_middle/src/traits/solve.rs
@@ -2,7 +2,10 @@ use std::ops::ControlFlow;
 
 use rustc_data_structures::intern::Interned;
 
-use crate::ty::{FallibleTypeFolder, Ty, TypeFoldable, TypeFolder, TypeVisitable, TypeVisitor};
+use crate::ty::{
+    ir::{self, TypeFoldable, TypeVisitable},
+    FallibleTypeFolder, Ty, TypeFolder, TypeVisitor,
+};
 
 #[derive(Debug, PartialEq, Eq, Copy, Clone, Hash)]
 pub struct ExternalConstraints<'tcx>(pub(crate) Interned<'tcx, ExternalConstraintsData<'tcx>>);
@@ -25,18 +28,20 @@ pub struct ExternalConstraintsData<'tcx> {
 
 impl<'tcx> TypeFoldable<'tcx> for ExternalConstraints<'tcx> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
-        Ok(FallibleTypeFolder::tcx(folder).intern_external_constraints(ExternalConstraintsData {
-            regions: (),
-            opaque_types: self
-                .opaque_types
-                .iter()
-                .map(|opaque| opaque.try_fold_with(folder))
-                .collect::<Result<_, F::Error>>()?,
-        }))
+        Ok(ir::FallibleTypeFolder::tcx(folder).intern_external_constraints(
+            ExternalConstraintsData {
+                regions: (),
+                opaque_types: self
+                    .opaque_types
+                    .iter()
+                    .map(|opaque| opaque.try_fold_with(folder))
+                    .collect::<Result<_, F::Error>>()?,
+            },
+        ))
     }
 
     fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
-        TypeFolder::tcx(folder).intern_external_constraints(ExternalConstraintsData {
+        ir::TypeFolder::tcx(folder).intern_external_constraints(ExternalConstraintsData {
             regions: (),
             opaque_types: self.opaque_types.iter().map(|opaque| opaque.fold_with(folder)).collect(),
         })
diff --git a/compiler/rustc_middle/src/ty/abstract_const.rs b/compiler/rustc_middle/src/ty/abstract_const.rs
index 5de758ad9babd..0f4a97d8aed82 100644
--- a/compiler/rustc_middle/src/ty/abstract_const.rs
+++ b/compiler/rustc_middle/src/ty/abstract_const.rs
@@ -1,7 +1,6 @@
 //! A subset of a mir body used for const evaluatability checking.
 use crate::ty::{
-    self, Const, EarlyBinder, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable,
-    TypeVisitable,
+    self, ir::TypeFolder, Const, EarlyBinder, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable,
 };
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def_id::DefId;
diff --git a/compiler/rustc_middle/src/ty/diagnostics.rs b/compiler/rustc_middle/src/ty/diagnostics.rs
index 0a30ae9d0aa78..eda801f352120 100644
--- a/compiler/rustc_middle/src/ty/diagnostics.rs
+++ b/compiler/rustc_middle/src/ty/diagnostics.rs
@@ -3,9 +3,10 @@
 use std::ops::ControlFlow;
 
 use crate::ty::{
-    visit::TypeVisitable, AliasTy, Const, ConstKind, DefIdTree, FallibleTypeFolder, InferConst,
-    InferTy, Opaque, PolyTraitPredicate, Projection, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable,
-    TypeSuperVisitable, TypeVisitor,
+    ir::{FallibleTypeFolder, TypeVisitor},
+    visit::TypeVisitable,
+    AliasTy, Const, ConstKind, DefIdTree, InferConst, InferTy, Opaque, PolyTraitPredicate,
+    Projection, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable, TypeSuperVisitable,
 };
 
 use rustc_data_structures::fx::FxHashMap;
diff --git a/compiler/rustc_middle/src/ty/erase_regions.rs b/compiler/rustc_middle/src/ty/erase_regions.rs
index 9e4f90caab0b5..25df0ee5560d5 100644
--- a/compiler/rustc_middle/src/ty/erase_regions.rs
+++ b/compiler/rustc_middle/src/ty/erase_regions.rs
@@ -1,5 +1,4 @@
-use crate::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
-use crate::ty::visit::TypeVisitable;
+use crate::ty::fold::{ir::TypeFolder, TypeFoldable, TypeSuperFoldable};
 use crate::ty::{self, Ty, TyCtxt, TypeFlags};
 
 pub(super) fn provide(providers: &mut ty::query::Providers) {
diff --git a/compiler/rustc_middle/src/ty/fold.rs b/compiler/rustc_middle/src/ty/fold.rs
index 1b8f6e12c3fe9..50222c6d70a92 100644
--- a/compiler/rustc_middle/src/ty/fold.rs
+++ b/compiler/rustc_middle/src/ty/fold.rs
@@ -48,7 +48,10 @@ use rustc_hir::def_id::DefId;
 
 use std::collections::BTreeMap;
 
-pub use ir::{FallibleTypeFolder, TypeFoldable, TypeFolder, TypeSuperFoldable};
+pub trait TypeFoldable<'tcx> = ir::TypeFoldable<'tcx> + TypeVisitable<'tcx>;
+pub trait TypeSuperFoldable<'tcx> = ir::TypeSuperFoldable<'tcx>;
+pub trait TypeFolder<'tcx> = ir::TypeFolder<'tcx>;
+pub trait FallibleTypeFolder<'tcx> = ir::FallibleTypeFolder<'tcx>;
 
 pub mod ir {
     use crate::ty::{self, ir::TypeVisitable, Binder, Ty, TyCtxt};
@@ -233,7 +236,7 @@ where
     pub ct_op: H,
 }
 
-impl<'tcx, F, G, H> TypeFolder<'tcx> for BottomUpFolder<'tcx, F, G, H>
+impl<'tcx, F, G, H> ir::TypeFolder<'tcx> for BottomUpFolder<'tcx, F, G, H>
 where
     F: FnMut(Ty<'tcx>) -> Ty<'tcx>,
     G: FnMut(ty::Region<'tcx>) -> ty::Region<'tcx>,
@@ -323,7 +326,7 @@ impl<'a, 'tcx> RegionFolder<'a, 'tcx> {
     }
 }
 
-impl<'a, 'tcx> TypeFolder<'tcx> for RegionFolder<'a, 'tcx> {
+impl<'a, 'tcx> ir::TypeFolder<'tcx> for RegionFolder<'a, 'tcx> {
     fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
         self.tcx
     }
@@ -397,7 +400,7 @@ impl<'tcx, D: BoundVarReplacerDelegate<'tcx>> BoundVarReplacer<'tcx, D> {
     }
 }
 
-impl<'tcx, D> TypeFolder<'tcx> for BoundVarReplacer<'tcx, D>
+impl<'tcx, D> ir::TypeFolder<'tcx> for BoundVarReplacer<'tcx, D>
 where
     D: BoundVarReplacerDelegate<'tcx>,
 {
@@ -663,7 +666,7 @@ impl<'tcx> Shifter<'tcx> {
     }
 }
 
-impl<'tcx> TypeFolder<'tcx> for Shifter<'tcx> {
+impl<'tcx> ir::TypeFolder<'tcx> for Shifter<'tcx> {
     fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
         self.tcx
     }
diff --git a/compiler/rustc_middle/src/ty/instance.rs b/compiler/rustc_middle/src/ty/instance.rs
index 8b4fccc58bd44..6c2c11aa5612d 100644
--- a/compiler/rustc_middle/src/ty/instance.rs
+++ b/compiler/rustc_middle/src/ty/instance.rs
@@ -1,6 +1,6 @@
 use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use crate::ty::print::{FmtPrinter, Printer};
-use crate::ty::{self, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable, TypeVisitable};
+use crate::ty::{self, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable};
 use crate::ty::{EarlyBinder, InternalSubsts, SubstsRef};
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def::Namespace;
@@ -674,7 +674,7 @@ fn polymorphize<'tcx>(
         tcx: TyCtxt<'tcx>,
     }
 
-    impl<'tcx> ty::TypeFolder<'tcx> for PolymorphizationFolder<'tcx> {
+    impl<'tcx> ty::ir::TypeFolder<'tcx> for PolymorphizationFolder<'tcx> {
         fn tcx<'a>(&'a self) -> TyCtxt<'tcx> {
             self.tcx
         }
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index f378c6fd8adf3..5d6bcb3de26e0 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -917,13 +917,13 @@ impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Term<'tcx> {
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for Term<'tcx> {
+impl<'tcx> ir::TypeFoldable<'tcx> for Term<'tcx> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         Ok(self.unpack().try_fold_with(folder)?.pack())
     }
 }
 
-impl<'tcx> TypeVisitable<'tcx> for Term<'tcx> {
+impl<'tcx> ir::TypeVisitable<'tcx> for Term<'tcx> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         self.unpack().visit_with(visitor)
     }
@@ -1619,7 +1619,7 @@ impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
+impl<'tcx> ir::TypeFoldable<'tcx> for ParamEnv<'tcx> {
     fn try_fold_with<F: ty::fold::FallibleTypeFolder<'tcx>>(
         self,
         folder: &mut F,
@@ -1632,7 +1632,7 @@ impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
     }
 }
 
-impl<'tcx> TypeVisitable<'tcx> for ParamEnv<'tcx> {
+impl<'tcx> ir::TypeVisitable<'tcx> for ParamEnv<'tcx> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         self.caller_bounds().visit_with(visitor)?;
         self.reveal().visit_with(visitor)
diff --git a/compiler/rustc_middle/src/ty/normalize_erasing_regions.rs b/compiler/rustc_middle/src/ty/normalize_erasing_regions.rs
index ee13920d52edd..7967534f96ab4 100644
--- a/compiler/rustc_middle/src/ty/normalize_erasing_regions.rs
+++ b/compiler/rustc_middle/src/ty/normalize_erasing_regions.rs
@@ -9,7 +9,10 @@
 
 use crate::mir;
 use crate::traits::query::NoSolution;
-use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder};
+use crate::ty::fold::{
+    ir::{FallibleTypeFolder, TypeFolder},
+    TypeFoldable,
+};
 use crate::ty::{self, EarlyBinder, SubstsRef, Ty, TyCtxt};
 
 #[derive(Debug, Copy, Clone, HashStable, TyEncodable, TyDecodable)]
diff --git a/compiler/rustc_middle/src/ty/opaque_types.rs b/compiler/rustc_middle/src/ty/opaque_types.rs
index a5ebdbc8792fb..db8f9c82dc3f3 100644
--- a/compiler/rustc_middle/src/ty/opaque_types.rs
+++ b/compiler/rustc_middle/src/ty/opaque_types.rs
@@ -1,5 +1,5 @@
 use crate::error::ConstNotUsedTraitAlias;
-use crate::ty::fold::{TypeFolder, TypeSuperFoldable};
+use crate::ty::fold::{ir::TypeFolder, TypeSuperFoldable};
 use crate::ty::subst::{GenericArg, GenericArgKind};
 use crate::ty::{self, Ty, TyCtxt, TypeFoldable};
 use rustc_data_structures::fx::FxHashMap;
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index c4a95ddacbfb1..06dd2595c09c3 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -2221,7 +2221,7 @@ struct RegionFolder<'a, 'tcx> {
             ),
 }
 
-impl<'a, 'tcx> ty::TypeFolder<'tcx> for RegionFolder<'a, 'tcx> {
+impl<'a, 'tcx> ty::ir::TypeFolder<'tcx> for RegionFolder<'a, 'tcx> {
     fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
         self.tcx
     }
@@ -2493,7 +2493,7 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
             }
         }
 
-        impl<'tcx> ty::visit::TypeVisitor<'tcx> for RegionNameCollector<'tcx> {
+        impl<'tcx> ty::visit::ir::TypeVisitor<'tcx> for RegionNameCollector<'tcx> {
             type BreakTy = ();
 
             fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
diff --git a/compiler/rustc_middle/src/ty/structural_impls.rs b/compiler/rustc_middle/src/ty/structural_impls.rs
index 1ef66b01ea0c6..590342a69523d 100644
--- a/compiler/rustc_middle/src/ty/structural_impls.rs
+++ b/compiler/rustc_middle/src/ty/structural_impls.rs
@@ -4,10 +4,10 @@
 
 use crate::mir::interpret;
 use crate::mir::{Field, ProjectionKind};
-use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeSuperFoldable};
+use crate::ty::fold::{ir::TypeSuperFoldable, FallibleTypeFolder, TypeFoldable};
 use crate::ty::print::{with_no_trimmed_paths, FmtPrinter, Printer};
-use crate::ty::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
-use crate::ty::{self, AliasTy, InferConst, Lift, Term, TermKind, Ty, TyCtxt};
+use crate::ty::visit::{ir::TypeSuperVisitable, TypeVisitable, TypeVisitor};
+use crate::ty::{self, ir, AliasTy, InferConst, Lift, Term, TermKind, Ty, TyCtxt};
 use rustc_data_structures::functor::IdFunctor;
 use rustc_hir::def::Namespace;
 use rustc_index::vec::{Idx, IndexVec};
@@ -363,19 +363,19 @@ impl<'a, 'tcx> Lift<'tcx> for ty::ParamEnv<'a> {
 // TypeFoldable implementations.
 
 /// AdtDefs are basically the same as a DefId.
-impl<'tcx> TypeFoldable<'tcx> for ty::AdtDef<'tcx> {
+impl<'tcx> ir::TypeFoldable<'tcx> for ty::AdtDef<'tcx> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, _folder: &mut F) -> Result<Self, F::Error> {
         Ok(self)
     }
 }
 
-impl<'tcx> TypeVisitable<'tcx> for ty::AdtDef<'tcx> {
+impl<'tcx> ir::TypeVisitable<'tcx> for ty::AdtDef<'tcx> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
         ControlFlow::Continue(())
     }
 }
 
-impl<'tcx, T: TypeFoldable<'tcx>, U: TypeFoldable<'tcx>> TypeFoldable<'tcx> for (T, U) {
+impl<'tcx, T: TypeFoldable<'tcx>, U: TypeFoldable<'tcx>> ir::TypeFoldable<'tcx> for (T, U) {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(
         self,
         folder: &mut F,
@@ -384,15 +384,15 @@ impl<'tcx, T: TypeFoldable<'tcx>, U: TypeFoldable<'tcx>> TypeFoldable<'tcx> for
     }
 }
 
-impl<'tcx, T: TypeVisitable<'tcx>, U: TypeVisitable<'tcx>> TypeVisitable<'tcx> for (T, U) {
+impl<'tcx, T: TypeVisitable<'tcx>, U: TypeVisitable<'tcx>> ir::TypeVisitable<'tcx> for (T, U) {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         self.0.visit_with(visitor)?;
         self.1.visit_with(visitor)
     }
 }
 
-impl<'tcx, A: TypeFoldable<'tcx>, B: TypeFoldable<'tcx>, C: TypeFoldable<'tcx>> TypeFoldable<'tcx>
-    for (A, B, C)
+impl<'tcx, A: TypeFoldable<'tcx>, B: TypeFoldable<'tcx>, C: TypeFoldable<'tcx>>
+    ir::TypeFoldable<'tcx> for (A, B, C)
 {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(
         self,
@@ -407,7 +407,7 @@ impl<'tcx, A: TypeFoldable<'tcx>, B: TypeFoldable<'tcx>, C: TypeFoldable<'tcx>>
 }
 
 impl<'tcx, A: TypeVisitable<'tcx>, B: TypeVisitable<'tcx>, C: TypeVisitable<'tcx>>
-    TypeVisitable<'tcx> for (A, B, C)
+    ir::TypeVisitable<'tcx> for (A, B, C)
 {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         self.0.visit_with(visitor)?;
@@ -442,7 +442,7 @@ EnumTypeTraversalImpl! {
     } where T: TypeVisitable<'tcx>, E: TypeVisitable<'tcx>,
 }
 
-impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Rc<T> {
+impl<'tcx, T: TypeFoldable<'tcx>> ir::TypeFoldable<'tcx> for Rc<T> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(
         mut self,
         folder: &mut F,
@@ -482,13 +482,13 @@ impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Rc<T> {
     }
 }
 
-impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Rc<T> {
+impl<'tcx, T: TypeVisitable<'tcx>> ir::TypeVisitable<'tcx> for Rc<T> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         (**self).visit_with(visitor)
     }
 }
 
-impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Arc<T> {
+impl<'tcx, T: TypeFoldable<'tcx>> ir::TypeFoldable<'tcx> for Arc<T> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(
         mut self,
         folder: &mut F,
@@ -528,61 +528,61 @@ impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Arc<T> {
     }
 }
 
-impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Arc<T> {
+impl<'tcx, T: TypeVisitable<'tcx>> ir::TypeVisitable<'tcx> for Arc<T> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         (**self).visit_with(visitor)
     }
 }
 
-impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<T> {
+impl<'tcx, T: TypeFoldable<'tcx>> ir::TypeFoldable<'tcx> for Box<T> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         self.try_map_id(|value| value.try_fold_with(folder))
     }
 }
 
-impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Box<T> {
+impl<'tcx, T: TypeVisitable<'tcx>> ir::TypeVisitable<'tcx> for Box<T> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         (**self).visit_with(visitor)
     }
 }
 
-impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Vec<T> {
+impl<'tcx, T: TypeFoldable<'tcx>> ir::TypeFoldable<'tcx> for Vec<T> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         self.try_map_id(|t| t.try_fold_with(folder))
     }
 }
 
-impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Vec<T> {
+impl<'tcx, T: TypeVisitable<'tcx>> ir::TypeVisitable<'tcx> for Vec<T> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         self.iter().try_for_each(|t| t.visit_with(visitor))
     }
 }
 
-impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for &[T] {
+impl<'tcx, T: TypeVisitable<'tcx>> ir::TypeVisitable<'tcx> for &[T] {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         self.iter().try_for_each(|t| t.visit_with(visitor))
     }
 }
 
-impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<[T]> {
+impl<'tcx, T: TypeFoldable<'tcx>> ir::TypeFoldable<'tcx> for Box<[T]> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         self.try_map_id(|t| t.try_fold_with(folder))
     }
 }
 
-impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Box<[T]> {
+impl<'tcx, T: TypeVisitable<'tcx>> ir::TypeVisitable<'tcx> for Box<[T]> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         self.iter().try_for_each(|t| t.visit_with(visitor))
     }
 }
 
-impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<'tcx, T> {
+impl<'tcx, T: TypeFoldable<'tcx>> ir::TypeFoldable<'tcx> for ty::Binder<'tcx, T> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         folder.try_fold_binder(self)
     }
 }
 
-impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for ty::Binder<'tcx, T> {
+impl<'tcx, T: TypeVisitable<'tcx>> ir::TypeVisitable<'tcx> for ty::Binder<'tcx, T> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         visitor.visit_binder(self)
     }
@@ -603,31 +603,31 @@ impl<'tcx, T: TypeVisitable<'tcx>> TypeSuperVisitable<'tcx> for ty::Binder<'tcx,
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>> {
+impl<'tcx> ir::TypeFoldable<'tcx> for &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_poly_existential_predicates(v))
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Const<'tcx>> {
+impl<'tcx> ir::TypeFoldable<'tcx> for &'tcx ty::List<ty::Const<'tcx>> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         ty::util::fold_list(self, folder, |tcx, v| tcx.mk_const_list(v.iter()))
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ProjectionKind> {
+impl<'tcx> ir::TypeFoldable<'tcx> for &'tcx ty::List<ProjectionKind> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_projs(v))
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for Ty<'tcx> {
+impl<'tcx> ir::TypeFoldable<'tcx> for Ty<'tcx> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         folder.try_fold_ty(self)
     }
 }
 
-impl<'tcx> TypeVisitable<'tcx> for Ty<'tcx> {
+impl<'tcx> ir::TypeVisitable<'tcx> for Ty<'tcx> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         visitor.visit_ty(*self)
     }
@@ -727,13 +727,13 @@ impl<'tcx> TypeSuperVisitable<'tcx> for Ty<'tcx> {
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for ty::Region<'tcx> {
+impl<'tcx> ir::TypeFoldable<'tcx> for ty::Region<'tcx> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         folder.try_fold_region(self)
     }
 }
 
-impl<'tcx> TypeVisitable<'tcx> for ty::Region<'tcx> {
+impl<'tcx> ir::TypeVisitable<'tcx> for ty::Region<'tcx> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         visitor.visit_region(*self)
     }
@@ -754,13 +754,13 @@ impl<'tcx> TypeSuperVisitable<'tcx> for ty::Region<'tcx> {
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for ty::Predicate<'tcx> {
+impl<'tcx> ir::TypeFoldable<'tcx> for ty::Predicate<'tcx> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         folder.try_fold_predicate(self)
     }
 }
 
-impl<'tcx> TypeVisitable<'tcx> for ty::Predicate<'tcx> {
+impl<'tcx> ir::TypeVisitable<'tcx> for ty::Predicate<'tcx> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         visitor.visit_predicate(*self)
     }
@@ -792,31 +792,31 @@ impl<'tcx> TypeSuperVisitable<'tcx> for ty::Predicate<'tcx> {
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Predicate<'tcx>> {
+impl<'tcx> ir::TypeFoldable<'tcx> for &'tcx ty::List<ty::Predicate<'tcx>> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_predicates(v))
     }
 }
 
-impl<'tcx, T: TypeFoldable<'tcx>, I: Idx> TypeFoldable<'tcx> for IndexVec<I, T> {
+impl<'tcx, T: TypeFoldable<'tcx>, I: Idx> ir::TypeFoldable<'tcx> for IndexVec<I, T> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         self.try_map_id(|x| x.try_fold_with(folder))
     }
 }
 
-impl<'tcx, T: TypeVisitable<'tcx>, I: Idx> TypeVisitable<'tcx> for IndexVec<I, T> {
+impl<'tcx, T: TypeVisitable<'tcx>, I: Idx> ir::TypeVisitable<'tcx> for IndexVec<I, T> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         self.iter().try_for_each(|t| t.visit_with(visitor))
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for ty::Const<'tcx> {
+impl<'tcx> ir::TypeFoldable<'tcx> for ty::Const<'tcx> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         folder.try_fold_const(self)
     }
 }
 
-impl<'tcx> TypeVisitable<'tcx> for ty::Const<'tcx> {
+impl<'tcx> ir::TypeVisitable<'tcx> for ty::Const<'tcx> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         visitor.visit_const(*self)
     }
@@ -844,13 +844,13 @@ impl<'tcx> TypeSuperVisitable<'tcx> for ty::Const<'tcx> {
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for InferConst<'tcx> {
+impl<'tcx> ir::TypeFoldable<'tcx> for InferConst<'tcx> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, _folder: &mut F) -> Result<Self, F::Error> {
         Ok(self)
     }
 }
 
-impl<'tcx> TypeVisitable<'tcx> for InferConst<'tcx> {
+impl<'tcx> ir::TypeVisitable<'tcx> for InferConst<'tcx> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
         ControlFlow::Continue(())
     }
@@ -862,7 +862,7 @@ impl<'tcx> TypeSuperVisitable<'tcx> for ty::UnevaluatedConst<'tcx> {
     }
 }
 
-impl<'tcx> TypeVisitable<'tcx> for TyAndLayout<'tcx, Ty<'tcx>> {
+impl<'tcx> ir::TypeVisitable<'tcx> for TyAndLayout<'tcx, Ty<'tcx>> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         visitor.visit_ty(self.ty)
     }
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index 89cde91e755e1..1976c7875f3b5 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -7,8 +7,10 @@ use crate::ty::subst::{GenericArg, InternalSubsts, SubstsRef};
 use crate::ty::visit::ValidateBoundVars;
 use crate::ty::InferTy::*;
 use crate::ty::{
-    self, AdtDef, DefIdTree, Discr, FallibleTypeFolder, Term, Ty, TyCtxt, TypeFlags, TypeFoldable,
-    TypeSuperFoldable, TypeSuperVisitable, TypeVisitable, TypeVisitor,
+    self,
+    ir::{FallibleTypeFolder, TypeVisitor},
+    AdtDef, DefIdTree, Discr, Term, Ty, TyCtxt, TypeFlags, TypeFoldable, TypeSuperFoldable,
+    TypeSuperVisitable, TypeVisitable,
 };
 use crate::ty::{List, ParamEnv};
 use hir::def::DefKind;
diff --git a/compiler/rustc_middle/src/ty/subst.rs b/compiler/rustc_middle/src/ty/subst.rs
index cf1bb5f8ac8db..195befe39f843 100644
--- a/compiler/rustc_middle/src/ty/subst.rs
+++ b/compiler/rustc_middle/src/ty/subst.rs
@@ -1,10 +1,10 @@
 // Type substitutions.
 
 use crate::ty::codec::{TyDecoder, TyEncoder};
-use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder, TypeSuperFoldable};
+use crate::ty::fold::{ir::TypeFolder, FallibleTypeFolder, TypeFoldable, TypeSuperFoldable};
 use crate::ty::sty::{ClosureSubsts, GeneratorSubsts, InlineConstSubsts};
 use crate::ty::visit::{TypeVisitable, TypeVisitor};
-use crate::ty::{self, Lift, List, ParamConst, Ty, TyCtxt};
+use crate::ty::{self, ir, Lift, List, ParamConst, Ty, TyCtxt};
 
 use rustc_data_structures::intern::Interned;
 use rustc_errors::{DiagnosticArgValue, IntoDiagnosticArg};
@@ -227,7 +227,7 @@ impl<'a, 'tcx> Lift<'tcx> for GenericArg<'a> {
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for GenericArg<'tcx> {
+impl<'tcx> ir::TypeFoldable<'tcx> for GenericArg<'tcx> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         match self.unpack() {
             GenericArgKind::Lifetime(lt) => lt.try_fold_with(folder).map(Into::into),
@@ -237,7 +237,7 @@ impl<'tcx> TypeFoldable<'tcx> for GenericArg<'tcx> {
     }
 }
 
-impl<'tcx> TypeVisitable<'tcx> for GenericArg<'tcx> {
+impl<'tcx> ir::TypeVisitable<'tcx> for GenericArg<'tcx> {
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         match self.unpack() {
             GenericArgKind::Lifetime(lt) => lt.visit_with(visitor),
@@ -475,7 +475,7 @@ impl<'tcx> InternalSubsts<'tcx> {
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for SubstsRef<'tcx> {
+impl<'tcx> ir::TypeFoldable<'tcx> for SubstsRef<'tcx> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         // This code is hot enough that it's worth specializing for the most
         // common length lists, to avoid the overhead of `SmallVec` creation.
@@ -503,7 +503,7 @@ impl<'tcx> TypeFoldable<'tcx> for SubstsRef<'tcx> {
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<Ty<'tcx>> {
+impl<'tcx> ir::TypeFoldable<'tcx> for &'tcx ty::List<Ty<'tcx>> {
     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
         // This code is fairly hot, though not as hot as `SubstsRef`.
         //
@@ -535,7 +535,7 @@ impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<Ty<'tcx>> {
     }
 }
 
-impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for &'tcx ty::List<T> {
+impl<'tcx, T: TypeVisitable<'tcx>> ir::TypeVisitable<'tcx> for &'tcx ty::List<T> {
     #[inline]
     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
         self.iter().try_for_each(|t| t.visit_with(visitor))
@@ -553,8 +553,8 @@ impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for &'tcx ty::List<T> {
 pub struct EarlyBinder<T>(pub T);
 
 /// For early binders, you should first call `subst` before using any visitors.
-impl<'tcx, T> !TypeFoldable<'tcx> for ty::EarlyBinder<T> {}
-impl<'tcx, T> !TypeVisitable<'tcx> for ty::EarlyBinder<T> {}
+impl<'tcx, T> !ir::TypeFoldable<'tcx> for ty::EarlyBinder<T> {}
+impl<'tcx, T> !ir::TypeVisitable<'tcx> for ty::EarlyBinder<T> {}
 
 impl<T> EarlyBinder<T> {
     pub fn as_ref(&self) -> EarlyBinder<&T> {
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
index 796164b0d6af3..5ce6a21137656 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -4,8 +4,8 @@ use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use crate::mir;
 use crate::ty::layout::IntegerExt;
 use crate::ty::{
-    self, DefIdTree, FallibleTypeFolder, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable,
-    TypeVisitable,
+    self, ir::TypeFolder, DefIdTree, FallibleTypeFolder, Ty, TyCtxt, TypeFoldable,
+    TypeSuperFoldable,
 };
 use crate::ty::{GenericArgKind, SubstsRef};
 use rustc_apfloat::Float as _;
diff --git a/compiler/rustc_middle/src/ty/visit.rs b/compiler/rustc_middle/src/ty/visit.rs
index fe3fc4c88c577..c292dc4272042 100644
--- a/compiler/rustc_middle/src/ty/visit.rs
+++ b/compiler/rustc_middle/src/ty/visit.rs
@@ -44,7 +44,9 @@ use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::sso::SsoHashSet;
 use std::ops::ControlFlow;
 
-pub use ir::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
+pub trait TypeVisitable<'tcx> = ir::TypeVisitable<'tcx>;
+pub trait TypeSuperVisitable<'tcx> = ir::TypeSuperVisitable<'tcx>;
+pub trait TypeVisitor<'tcx> = ir::TypeVisitor<'tcx>;
 
 pub mod ir {
     use crate::ty::{self, Binder, Ty, TypeFlags};
@@ -292,7 +294,7 @@ impl<'tcx> TyCtxt<'tcx> {
             callback: F,
         }
 
-        impl<'tcx, F> TypeVisitor<'tcx> for RegionVisitor<F>
+        impl<'tcx, F> ir::TypeVisitor<'tcx> for RegionVisitor<F>
         where
             F: FnMut(ty::Region<'tcx>) -> bool,
         {
@@ -394,7 +396,7 @@ impl<'tcx> ValidateBoundVars<'tcx> {
     }
 }
 
-impl<'tcx> TypeVisitor<'tcx> for ValidateBoundVars<'tcx> {
+impl<'tcx> ir::TypeVisitor<'tcx> for ValidateBoundVars<'tcx> {
     type BreakTy = ();
 
     fn visit_binder<T: TypeVisitable<'tcx>>(
@@ -506,7 +508,7 @@ struct HasEscapingVarsVisitor {
     outer_index: ty::DebruijnIndex,
 }
 
-impl<'tcx> TypeVisitor<'tcx> for HasEscapingVarsVisitor {
+impl<'tcx> ir::TypeVisitor<'tcx> for HasEscapingVarsVisitor {
     type BreakTy = FoundEscapingVars;
 
     fn visit_binder<T: TypeVisitable<'tcx>>(
@@ -583,7 +585,7 @@ impl std::fmt::Debug for HasTypeFlagsVisitor {
     }
 }
 
-impl<'tcx> TypeVisitor<'tcx> for HasTypeFlagsVisitor {
+impl<'tcx> ir::TypeVisitor<'tcx> for HasTypeFlagsVisitor {
     type BreakTy = FoundFlags;
 
     #[inline]
@@ -653,7 +655,7 @@ impl LateBoundRegionsCollector {
     }
 }
 
-impl<'tcx> TypeVisitor<'tcx> for LateBoundRegionsCollector {
+impl<'tcx> ir::TypeVisitor<'tcx> for LateBoundRegionsCollector {
     fn visit_binder<T: TypeVisitable<'tcx>>(
         &mut self,
         t: &Binder<'tcx, T>,
@@ -715,7 +717,7 @@ impl MaxUniverse {
     }
 }
 
-impl<'tcx> TypeVisitor<'tcx> for MaxUniverse {
+impl<'tcx> ir::TypeVisitor<'tcx> for MaxUniverse {
     fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
         if let ty::Placeholder(placeholder) = t.kind() {
             self.max_universe = ty::UniverseIndex::from_u32(
diff --git a/compiler/rustc_monomorphize/src/collector.rs b/compiler/rustc_monomorphize/src/collector.rs
index 31a3ffbb1d891..83b8988cecaf8 100644
--- a/compiler/rustc_monomorphize/src/collector.rs
+++ b/compiler/rustc_monomorphize/src/collector.rs
@@ -189,9 +189,7 @@ use rustc_middle::ty::adjustment::{CustomCoerceUnsized, PointerCast};
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::query::TyCtxtAt;
 use rustc_middle::ty::subst::{GenericArgKind, InternalSubsts};
-use rustc_middle::ty::{
-    self, GenericParamDefKind, Instance, Ty, TyCtxt, TypeFoldable, TypeVisitable, VtblEntry,
-};
+use rustc_middle::ty::{self, GenericParamDefKind, Instance, Ty, TyCtxt, TypeFoldable, VtblEntry};
 use rustc_middle::{middle::codegen_fn_attrs::CodegenFnAttrFlags, mir::visit::TyContext};
 use rustc_session::config::EntryFnType;
 use rustc_session::lint::builtin::LARGE_ASSIGNMENTS;
diff --git a/compiler/rustc_monomorphize/src/polymorphize.rs b/compiler/rustc_monomorphize/src/polymorphize.rs
index cf13d4584a124..8589af89e860f 100644
--- a/compiler/rustc_monomorphize/src/polymorphize.rs
+++ b/compiler/rustc_monomorphize/src/polymorphize.rs
@@ -15,7 +15,7 @@ use rustc_middle::ty::{
     self,
     query::Providers,
     subst::SubstsRef,
-    visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor},
+    visit::{ir::TypeVisitor, TypeSuperVisitable, TypeVisitable},
     Const, Ty, TyCtxt, UnusedGenericParams,
 };
 use rustc_span::symbol::sym;
diff --git a/compiler/rustc_privacy/src/lib.rs b/compiler/rustc_privacy/src/lib.rs
index 4355286153223..b27f02686b0f0 100644
--- a/compiler/rustc_privacy/src/lib.rs
+++ b/compiler/rustc_privacy/src/lib.rs
@@ -28,7 +28,7 @@ use rustc_middle::span_bug;
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::subst::InternalSubsts;
 use rustc_middle::ty::{self, Const, DefIdTree, GenericParamDefKind};
-use rustc_middle::ty::{TraitRef, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor};
+use rustc_middle::ty::{ir::TypeVisitor, TraitRef, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable};
 use rustc_session::lint;
 use rustc_span::hygiene::Transparency;
 use rustc_span::symbol::{kw, sym, Ident};
diff --git a/compiler/rustc_trait_selection/src/infer.rs b/compiler/rustc_trait_selection/src/infer.rs
index 50c1787ef8c3d..c0bfe152a1e8c 100644
--- a/compiler/rustc_trait_selection/src/infer.rs
+++ b/compiler/rustc_trait_selection/src/infer.rs
@@ -6,7 +6,7 @@ use rustc_hir::lang_items::LangItem;
 use rustc_middle::arena::ArenaAllocatable;
 use rustc_middle::infer::canonical::{Canonical, CanonicalQueryResponse, QueryResponse};
 use rustc_middle::traits::query::Fallible;
-use rustc_middle::ty::{self, Ty, TypeFoldable, TypeVisitable};
+use rustc_middle::ty::{self, Ty, TypeFoldable};
 use rustc_middle::ty::{GenericArg, ToPredicate};
 use rustc_span::{Span, DUMMY_SP};
 
diff --git a/compiler/rustc_trait_selection/src/solve/project_goals.rs b/compiler/rustc_trait_selection/src/solve/project_goals.rs
index 4fea49893a6c6..3c74224c71b3b 100644
--- a/compiler/rustc_trait_selection/src/solve/project_goals.rs
+++ b/compiler/rustc_trait_selection/src/solve/project_goals.rs
@@ -14,7 +14,7 @@ use rustc_infer::traits::specialization_graph::LeafDef;
 use rustc_infer::traits::Reveal;
 use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
 use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_middle::ty::{ProjectionPredicate, TypeSuperVisitable, TypeVisitor};
+use rustc_middle::ty::{ir::TypeVisitor, ProjectionPredicate, TypeSuperVisitable};
 use rustc_middle::ty::{ToPredicate, TypeVisitable};
 use rustc_span::{sym, DUMMY_SP};
 use std::iter;
diff --git a/compiler/rustc_trait_selection/src/traits/auto_trait.rs b/compiler/rustc_trait_selection/src/traits/auto_trait.rs
index 6a840704e8637..d134722e89932 100644
--- a/compiler/rustc_trait_selection/src/traits/auto_trait.rs
+++ b/compiler/rustc_trait_selection/src/traits/auto_trait.rs
@@ -8,7 +8,7 @@ use crate::infer::region_constraints::{Constraint, RegionConstraintData};
 use crate::infer::InferCtxt;
 use crate::traits::project::ProjectAndUnifyResult;
 use rustc_middle::mir::interpret::ErrorHandled;
-use rustc_middle::ty::fold::{TypeFolder, TypeSuperFoldable};
+use rustc_middle::ty::fold::{ir::TypeFolder, TypeSuperFoldable};
 use rustc_middle::ty::visit::TypeVisitable;
 use rustc_middle::ty::{ImplPolarity, Region, RegionVid};
 
diff --git a/compiler/rustc_trait_selection/src/traits/coherence.rs b/compiler/rustc_trait_selection/src/traits/coherence.rs
index 61f508a7a0750..9f69492863157 100644
--- a/compiler/rustc_trait_selection/src/traits/coherence.rs
+++ b/compiler/rustc_trait_selection/src/traits/coherence.rs
@@ -22,7 +22,7 @@ use rustc_infer::traits::util;
 use rustc_middle::traits::specialization_graph::OverlapMode;
 use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
 use rustc_middle::ty::visit::TypeVisitable;
-use rustc_middle::ty::{self, ImplSubject, Ty, TyCtxt, TypeVisitor};
+use rustc_middle::ty::{self, ir::TypeVisitor, ImplSubject, Ty, TyCtxt};
 use rustc_span::symbol::sym;
 use rustc_span::DUMMY_SP;
 use std::fmt::Debug;
diff --git a/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs b/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
index 786473457ae43..3a23e2eefc28f 100644
--- a/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
+++ b/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
@@ -14,7 +14,7 @@ use rustc_middle::mir::interpret::ErrorHandled;
 
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::abstract_const::NotConstEvaluatable;
-use rustc_middle::ty::{self, TyCtxt, TypeVisitable, TypeVisitor};
+use rustc_middle::ty::{self, ir::TypeVisitor, TyCtxt, TypeVisitable};
 
 use rustc_span::Span;
 use std::ops::ControlFlow;
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
index 4867855c2ae95..68b2f36d15e59 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
@@ -34,11 +34,10 @@ use rustc_infer::infer::{InferOk, TypeTrace};
 use rustc_middle::traits::select::OverflowError;
 use rustc_middle::ty::abstract_const::NotConstEvaluatable;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
-use rustc_middle::ty::fold::{TypeFolder, TypeSuperFoldable};
+use rustc_middle::ty::fold::{ir::TypeFolder, TypeSuperFoldable};
 use rustc_middle::ty::print::{with_forced_trimmed_paths, FmtPrinter, Print};
 use rustc_middle::ty::{
     self, SubtypePredicate, ToPolyTraitRef, ToPredicate, TraitRef, Ty, TyCtxt, TypeFoldable,
-    TypeVisitable,
 };
 use rustc_session::config::TraitSolver;
 use rustc_session::Limit;
@@ -2964,7 +2963,7 @@ impl ArgKind {
 
 struct HasNumericInferVisitor;
 
-impl<'tcx> ty::TypeVisitor<'tcx> for HasNumericInferVisitor {
+impl<'tcx> ty::ir::TypeVisitor<'tcx> for HasNumericInferVisitor {
     type BreakTy = ();
 
     fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index cca178299df11..5b98375cdd815 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -30,10 +30,10 @@ use rustc_middle::hir::map;
 use rustc_middle::ty::error::TypeError::{self, Sorts};
 use rustc_middle::ty::relate::TypeRelation;
 use rustc_middle::ty::{
-    self, suggest_arbitrary_trait_bound, suggest_constraining_type_param, AdtKind, DefIdTree,
-    GeneratorDiagnosticData, GeneratorInteriorTypeCause, Infer, InferTy, InternalSubsts,
-    IsSuggestable, ToPredicate, Ty, TyCtxt, TypeAndMut, TypeFoldable, TypeFolder,
-    TypeSuperFoldable, TypeVisitable, TypeckResults,
+    self, ir::TypeFolder, suggest_arbitrary_trait_bound, suggest_constraining_type_param, AdtKind,
+    DefIdTree, GeneratorDiagnosticData, GeneratorInteriorTypeCause, Infer, InferTy, InternalSubsts,
+    IsSuggestable, ToPredicate, Ty, TyCtxt, TypeAndMut, TypeFoldable, TypeSuperFoldable,
+    TypeckResults,
 };
 use rustc_span::def_id::LocalDefId;
 use rustc_span::symbol::{sym, Ident, Symbol};
diff --git a/compiler/rustc_trait_selection/src/traits/mod.rs b/compiler/rustc_trait_selection/src/traits/mod.rs
index 83458017e00f0..490261dcf5f8d 100644
--- a/compiler/rustc_trait_selection/src/traits/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/mod.rs
@@ -481,7 +481,7 @@ fn is_impossible_method(tcx: TyCtxt<'_>, (impl_def_id, trait_item_def_id): (DefI
         generics: &'tcx ty::Generics,
         trait_item_def_id: DefId,
     }
-    impl<'tcx> ty::TypeVisitor<'tcx> for ReferencesOnlyParentGenerics<'tcx> {
+    impl<'tcx> ty::ir::TypeVisitor<'tcx> for ReferencesOnlyParentGenerics<'tcx> {
         type BreakTy = ();
         fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
             // If this is a parameter from the trait item's own generics, then bail
diff --git a/compiler/rustc_trait_selection/src/traits/object_safety.rs b/compiler/rustc_trait_selection/src/traits/object_safety.rs
index 977446894e770..428dcbf6ea734 100644
--- a/compiler/rustc_trait_selection/src/traits/object_safety.rs
+++ b/compiler/rustc_trait_selection/src/traits/object_safety.rs
@@ -19,7 +19,7 @@ use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_middle::ty::subst::{GenericArg, InternalSubsts};
 use rustc_middle::ty::{
-    self, EarlyBinder, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor,
+    self, ir::TypeVisitor, EarlyBinder, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable,
 };
 use rustc_middle::ty::{Predicate, ToPredicate};
 use rustc_session::lint::builtin::WHERE_CLAUSES_OBJECT_SAFETY;
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index c2bce774bb531..b16fb819466b0 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -30,7 +30,7 @@ use rustc_infer::infer::at::At;
 use rustc_infer::infer::resolve::OpportunisticRegionResolver;
 use rustc_infer::traits::ImplSourceBuiltinData;
 use rustc_middle::traits::select::OverflowError;
-use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
+use rustc_middle::ty::fold::{ir::TypeFolder, TypeFoldable, TypeSuperFoldable};
 use rustc_middle::ty::visit::{MaxUniverse, TypeVisitable};
 use rustc_middle::ty::DefIdTree;
 use rustc_middle::ty::{self, Term, ToPredicate, Ty, TyCtxt};
diff --git a/compiler/rustc_trait_selection/src/traits/query/normalize.rs b/compiler/rustc_trait_selection/src/traits/query/normalize.rs
index 1b2533a5cf649..30fa473eb0611 100644
--- a/compiler/rustc_trait_selection/src/traits/query/normalize.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/normalize.rs
@@ -11,9 +11,9 @@ use crate::traits::{ObligationCause, PredicateObligation, Reveal};
 use rustc_data_structures::sso::SsoHashMap;
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_infer::traits::Normalized;
-use rustc_middle::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeSuperFoldable};
+use rustc_middle::ty::fold::{ir::FallibleTypeFolder, TypeFoldable, TypeSuperFoldable};
 use rustc_middle::ty::visit::{TypeSuperVisitable, TypeVisitable};
-use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitor};
+use rustc_middle::ty::{self, ir::TypeVisitor, Ty, TyCtxt};
 use rustc_span::DUMMY_SP;
 
 use std::ops::ControlFlow;
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index 45c4811321a01..302adb7976689 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -48,7 +48,7 @@ use rustc_middle::ty::fold::BottomUpFolder;
 use rustc_middle::ty::relate::TypeRelation;
 use rustc_middle::ty::SubstsRef;
 use rustc_middle::ty::{self, EarlyBinder, PolyProjectionPredicate, ToPolyTraitRef, ToPredicate};
-use rustc_middle::ty::{Ty, TyCtxt, TypeFoldable, TypeVisitable};
+use rustc_middle::ty::{Ty, TyCtxt, TypeFoldable};
 use rustc_session::config::TraitSolver;
 use rustc_span::symbol::sym;
 
diff --git a/compiler/rustc_trait_selection/src/traits/structural_match.rs b/compiler/rustc_trait_selection/src/traits/structural_match.rs
index 69b965f3a389a..53570295d8b82 100644
--- a/compiler/rustc_trait_selection/src/traits/structural_match.rs
+++ b/compiler/rustc_trait_selection/src/traits/structural_match.rs
@@ -1,6 +1,6 @@
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
-use rustc_middle::ty::{self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor};
+use rustc_middle::ty::{self, ir::TypeVisitor, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable};
 use rustc_span::Span;
 use std::ops::ControlFlow;
 
diff --git a/compiler/rustc_traits/src/chalk/db.rs b/compiler/rustc_traits/src/chalk/db.rs
index 7101f4042694f..5e32b23fdcaae 100644
--- a/compiler/rustc_traits/src/chalk/db.rs
+++ b/compiler/rustc_traits/src/chalk/db.rs
@@ -769,7 +769,7 @@ struct ReplaceOpaqueTyFolder<'tcx> {
     binder_index: ty::DebruijnIndex,
 }
 
-impl<'tcx> ty::TypeFolder<'tcx> for ReplaceOpaqueTyFolder<'tcx> {
+impl<'tcx> ty::ir::TypeFolder<'tcx> for ReplaceOpaqueTyFolder<'tcx> {
     fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
         self.tcx
     }
diff --git a/compiler/rustc_traits/src/chalk/lowering.rs b/compiler/rustc_traits/src/chalk/lowering.rs
index 4f71dcde81878..743320e248d96 100644
--- a/compiler/rustc_traits/src/chalk/lowering.rs
+++ b/compiler/rustc_traits/src/chalk/lowering.rs
@@ -35,8 +35,9 @@ use rustc_ast::ast;
 use rustc_middle::traits::{ChalkEnvironmentAndGoal, ChalkRustInterner as RustInterner};
 use rustc_middle::ty::subst::{GenericArg, GenericArgKind, SubstsRef};
 use rustc_middle::ty::{
-    self, Binder, Region, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable,
-    TypeSuperVisitable, TypeVisitable, TypeVisitor,
+    self,
+    ir::{TypeFolder, TypeVisitor},
+    Binder, Region, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable, TypeSuperVisitable, TypeVisitable,
 };
 use rustc_span::def_id::DefId;
 
diff --git a/compiler/rustc_traits/src/chalk/mod.rs b/compiler/rustc_traits/src/chalk/mod.rs
index 5855a8e28dd1d..f33f9edd6279e 100644
--- a/compiler/rustc_traits/src/chalk/mod.rs
+++ b/compiler/rustc_traits/src/chalk/mod.rs
@@ -9,7 +9,7 @@ pub(crate) mod lowering;
 use rustc_middle::infer::canonical::{CanonicalTyVarKind, CanonicalVarKind};
 use rustc_middle::traits::ChalkRustInterner;
 use rustc_middle::ty::query::Providers;
-use rustc_middle::ty::{self, TyCtxt, TypeFoldable, TypeVisitable};
+use rustc_middle::ty::{self, TyCtxt, TypeFoldable};
 
 use rustc_infer::infer::canonical::{
     Canonical, CanonicalVarValues, Certainty, QueryRegionConstraints, QueryResponse,
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 42bdbddbce617..bf3bbeb2dd133 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -20,7 +20,7 @@ use rustc_hir::PredicateOrigin;
 use rustc_hir_analysis::hir_ty_to_ty;
 use rustc_infer::infer::region_constraints::{Constraint, RegionConstraintData};
 use rustc_middle::middle::resolve_lifetime as rl;
-use rustc_middle::ty::fold::TypeFolder;
+use rustc_middle::ty::fold::ir::TypeFolder;
 use rustc_middle::ty::InternalSubsts;
 use rustc_middle::ty::TypeVisitable;
 use rustc_middle::ty::{self, AdtKind, DefIdTree, EarlyBinder, Ty, TyCtxt};
diff --git a/src/tools/clippy/clippy_utils/src/mir/possible_borrower.rs b/src/tools/clippy/clippy_utils/src/mir/possible_borrower.rs
index 5836eb73bd94c..fd9c83759a9c2 100644
--- a/src/tools/clippy/clippy_utils/src/mir/possible_borrower.rs
+++ b/src/tools/clippy/clippy_utils/src/mir/possible_borrower.rs
@@ -4,7 +4,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_index::bit_set::{BitSet, HybridBitSet};
 use rustc_lint::LateContext;
 use rustc_middle::mir::{self, visit::Visitor as _, Mutability};
-use rustc_middle::ty::{self, visit::TypeVisitor};
+use rustc_middle::ty::{self, visit::ir::TypeVisitor};
 use rustc_mir_dataflow::{impls::MaybeStorageLive, Analysis, ResultsCursor};
 use std::borrow::Cow;
 use std::ops::ControlFlow;
diff --git a/src/tools/clippy/clippy_utils/src/ty.rs b/src/tools/clippy/clippy_utils/src/ty.rs
index c48d27b05f045..1635b75f718f2 100644
--- a/src/tools/clippy/clippy_utils/src/ty.rs
+++ b/src/tools/clippy/clippy_utils/src/ty.rs
@@ -17,7 +17,7 @@ use rustc_lint::LateContext;
 use rustc_middle::mir::interpret::{ConstValue, Scalar};
 use rustc_middle::ty::{
     self, AdtDef, AliasTy, AssocKind, Binder, BoundRegion, DefIdTree, FnSig, IntTy, List, ParamEnv, Predicate,
-    PredicateKind, Region, RegionKind, SubstsRef, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor, UintTy,
+    PredicateKind, Region, RegionKind, SubstsRef, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, ir::TypeVisitor, UintTy,
     VariantDef, VariantDiscr,
 };
 use rustc_middle::ty::{GenericArg, GenericArgKind};
diff --git a/tests/ui/impl-trait/normalize-tait-in-const.stderr b/tests/ui/impl-trait/normalize-tait-in-const.stderr
index b9fc8726ffc0b..99eed29207b4a 100644
--- a/tests/ui/impl-trait/normalize-tait-in-const.stderr
+++ b/tests/ui/impl-trait/normalize-tait-in-const.stderr
@@ -1,4 +1,4 @@
-error: internal compiler error: compiler/rustc_middle/src/ty/normalize_erasing_regions.rs:198:90: Failed to normalize <for<'a, 'b> fn(&'a Alias<'b>) {foo} as std::ops::FnOnce<(&&S,)>>::Output, maybe try to call `try_normalize_erasing_regions` instead
+error: internal compiler error: compiler/rustc_middle/src/ty/normalize_erasing_regions.rs:201:90: Failed to normalize <for<'a, 'b> fn(&'a Alias<'b>) {foo} as std::ops::FnOnce<(&&S,)>>::Output, maybe try to call `try_normalize_erasing_regions` instead
 
 query stack during panic:
 #0 [eval_to_allocation_raw] const-evaluating + checking `BAR`