diff --git a/compiler/rustc_macros/src/serialize.rs b/compiler/rustc_macros/src/serialize.rs
index 653c728ee42..a39b4413981 100644
--- a/compiler/rustc_macros/src/serialize.rs
+++ b/compiler/rustc_macros/src/serialize.rs
@@ -8,7 +8,7 @@ pub fn type_decodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2:
     if !s.ast().generics.lifetimes().any(|lt| lt.lifetime.ident == "tcx") {
         s.add_impl_generic(parse_quote! { 'tcx });
     }
-    s.add_impl_generic(parse_quote! {#decoder_ty: ::rustc_type_ir::codec::TyDecoder<I = ::rustc_middle::ty::TyInterner<'tcx>>});
+    s.add_impl_generic(parse_quote! {#decoder_ty: ::rustc_type_ir::codec::TyDecoder<I = ::rustc_middle::ty::TyCtxt<'tcx>>});
     s.add_bounds(synstructure::AddBounds::Generics);
 
     decodable_body(s, decoder_ty)
@@ -95,7 +95,7 @@ pub fn type_encodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2:
         s.add_impl_generic(parse_quote! {'tcx});
     }
     let encoder_ty = quote! { __E };
-    s.add_impl_generic(parse_quote! {#encoder_ty: ::rustc_type_ir::codec::TyEncoder<I = ::rustc_middle::ty::TyInterner<'tcx>>});
+    s.add_impl_generic(parse_quote! {#encoder_ty: ::rustc_type_ir::codec::TyEncoder<I = ::rustc_middle::ty::TyCtxt<'tcx>>});
     s.add_bounds(synstructure::AddBounds::Generics);
 
     encodable_body(s, encoder_ty, false)
diff --git a/compiler/rustc_metadata/src/rmeta/decoder.rs b/compiler/rustc_metadata/src/rmeta/decoder.rs
index d9f21fa9bb9..775ebb48402 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder.rs
@@ -24,8 +24,8 @@
 use rustc_middle::thir;
 use rustc_middle::ty::codec::TyDecoder;
 use rustc_middle::ty::fast_reject::SimplifiedType;
+use rustc_middle::ty::GeneratorDiagnosticData;
 use rustc_middle::ty::{self, ParameterizedOverTcx, Ty, TyCtxt, Visibility};
-use rustc_middle::ty::{GeneratorDiagnosticData, TyInterner};
 use rustc_serialize::{opaque, Decodable, Decoder};
 use rustc_session::cstore::{
     CrateSource, ExternCrate, ForeignModule, LinkagePreference, NativeLib,
@@ -380,11 +380,11 @@ pub fn read_raw_bytes(&mut self, len: usize) -> &[u8] {
 impl<'a, 'tcx> TyDecoder for DecodeContext<'a, 'tcx> {
     const CLEAR_CROSS_CRATE: bool = true;
 
-    type I = TyInterner<'tcx>;
+    type I = TyCtxt<'tcx>;
 
     #[inline]
     fn interner(&self) -> Self::I {
-        TyInterner { tcx: self.tcx() }
+        self.tcx()
     }
 
     #[inline]
diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
index 2a862502f38..5a40986307c 100644
--- a/compiler/rustc_metadata/src/rmeta/encoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -26,7 +26,7 @@
 use rustc_middle::ty::codec::TyEncoder;
 use rustc_middle::ty::fast_reject::{self, SimplifiedType, TreatParams};
 use rustc_middle::ty::query::Providers;
-use rustc_middle::ty::{self, SymbolName, Ty, TyCtxt, TyInterner};
+use rustc_middle::ty::{self, SymbolName, Ty, TyCtxt};
 use rustc_serialize::{opaque, Encodable, Encoder};
 use rustc_session::config::CrateType;
 use rustc_session::cstore::{ForeignModule, LinkagePreference, NativeLib};
@@ -316,7 +316,7 @@ fn encode(&self, s: &mut EncodeContext<'a, 'tcx>) -> opaque::EncodeResult {
 impl<'a, 'tcx> TyEncoder for EncodeContext<'a, 'tcx> {
     const CLEAR_CROSS_CRATE: bool = true;
 
-    type I = TyInterner<'tcx>;
+    type I = TyCtxt<'tcx>;
 
     fn position(&self) -> usize {
         self.opaque.position()
diff --git a/compiler/rustc_middle/src/mir/interpret/mod.rs b/compiler/rustc_middle/src/mir/interpret/mod.rs
index 926afa8ccb6..06cd6a66e39 100644
--- a/compiler/rustc_middle/src/mir/interpret/mod.rs
+++ b/compiler/rustc_middle/src/mir/interpret/mod.rs
@@ -115,7 +115,7 @@ macro_rules! throw_machine_stop {
 use crate::mir;
 use crate::ty::codec::{TyDecoder, TyEncoder};
 use crate::ty::subst::GenericArgKind;
-use crate::ty::{self, Instance, Ty, TyCtxt, TyInterner};
+use crate::ty::{self, Instance, Ty, TyCtxt};
 
 pub use self::error::{
     struct_error, CheckInAllocMsg, ErrorHandled, EvalToAllocationRawResult, EvalToConstValueResult,
@@ -203,7 +203,7 @@ enum AllocDiscriminant {
     Static,
 }
 
-pub fn specialized_encode_alloc_id<'tcx, E: TyEncoder<I = TyInterner<'tcx>>>(
+pub fn specialized_encode_alloc_id<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>>(
     encoder: &mut E,
     tcx: TyCtxt<'tcx>,
     alloc_id: AllocId,
@@ -277,7 +277,7 @@ impl<'s> AllocDecodingSession<'s> {
     /// Decodes an `AllocId` in a thread-safe way.
     pub fn decode_alloc_id<'tcx, D>(&self, decoder: &mut D) -> AllocId
     where
-        D: TyDecoder<I = TyInterner<'tcx>>,
+        D: TyDecoder<I = TyCtxt<'tcx>>,
     {
         // Read the index of the allocation.
         let idx = usize::try_from(decoder.read_u32()).unwrap();
@@ -305,7 +305,7 @@ pub fn decode_alloc_id<'tcx, D>(&self, decoder: &mut D) -> AllocId
                         AllocDiscriminant::Alloc => {
                             // If this is an allocation, we need to reserve an
                             // `AllocId` so we can decode cyclic graphs.
-                            let alloc_id = decoder.interner().tcx.reserve_alloc_id();
+                            let alloc_id = decoder.interner().reserve_alloc_id();
                             *entry =
                                 State::InProgress(TinyList::new_single(self.session_id), alloc_id);
                             Some(alloc_id)
@@ -349,7 +349,7 @@ pub fn decode_alloc_id<'tcx, D>(&self, decoder: &mut D) -> AllocId
                     // We already have a reserved `AllocId`.
                     let alloc_id = alloc_id.unwrap();
                     trace!("decoded alloc {:?}: {:#?}", alloc_id, alloc);
-                    decoder.interner().tcx.set_alloc_id_same_memory(alloc_id, alloc);
+                    decoder.interner().set_alloc_id_same_memory(alloc_id, alloc);
                     alloc_id
                 }
                 AllocDiscriminant::Fn => {
@@ -357,7 +357,7 @@ pub fn decode_alloc_id<'tcx, D>(&self, decoder: &mut D) -> AllocId
                     trace!("creating fn alloc ID");
                     let instance = ty::Instance::decode(decoder);
                     trace!("decoded fn alloc instance: {:?}", instance);
-                    let alloc_id = decoder.interner().tcx.create_fn_alloc(instance);
+                    let alloc_id = decoder.interner().create_fn_alloc(instance);
                     alloc_id
                 }
                 AllocDiscriminant::Static => {
@@ -365,7 +365,7 @@ pub fn decode_alloc_id<'tcx, D>(&self, decoder: &mut D) -> AllocId
                     trace!("creating extern static alloc ID");
                     let did = <DefId as Decodable<D>>::decode(decoder);
                     trace!("decoded static def-ID: {:?}", did);
-                    let alloc_id = decoder.interner().tcx.create_static_alloc(did);
+                    let alloc_id = decoder.interner().create_static_alloc(did);
                     alloc_id
                 }
             }
diff --git a/compiler/rustc_middle/src/ty/codec.rs b/compiler/rustc_middle/src/ty/codec.rs
index 2298cb4098b..1e2d1fbeb4b 100644
--- a/compiler/rustc_middle/src/ty/codec.rs
+++ b/compiler/rustc_middle/src/ty/codec.rs
@@ -17,7 +17,7 @@
 use crate::ty::subst::SubstsRef;
 use crate::ty::{self, AdtDef, Ty};
 use rustc_data_structures::fx::FxHashMap;
-use rustc_middle::ty::TyInterner;
+use rustc_middle::ty::TyCtxt;
 use rustc_serialize::{Decodable, Encodable};
 use rustc_span::Span;
 pub use rustc_type_ir::{TyDecoder, TyEncoder};
@@ -36,7 +36,7 @@ pub trait EncodableWithShorthand<E: TyEncoder>: Copy + Eq + Hash {
 }
 
 #[allow(rustc::usage_of_ty_tykind)]
-impl<'tcx, E: TyEncoder<I = TyInterner<'tcx>>> EncodableWithShorthand<E> for Ty<'tcx> {
+impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> EncodableWithShorthand<E> for Ty<'tcx> {
     type Variant = ty::TyKind<'tcx>;
 
     #[inline]
@@ -45,9 +45,7 @@ fn variant(&self) -> &Self::Variant {
     }
 }
 
-impl<'tcx, E: TyEncoder<I = TyInterner<'tcx>>> EncodableWithShorthand<E>
-    for ty::PredicateKind<'tcx>
-{
+impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> EncodableWithShorthand<E> for ty::PredicateKind<'tcx> {
     type Variant = ty::PredicateKind<'tcx>;
 
     #[inline]
@@ -66,7 +64,7 @@ fn variant(&self) -> &Self::Variant {
 ///
 /// `Decodable` can still be implemented in cases where `Decodable` is required
 /// by a trait bound.
-pub trait RefDecodable<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> {
+pub trait RefDecodable<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> {
     fn decode(d: &mut D) -> &'tcx Self;
 }
 
@@ -77,7 +75,7 @@ pub fn encode_with_shorthand<'tcx, E, T, M>(
     cache: M,
 ) -> Result<(), E::Error>
 where
-    E: TyEncoder<I = TyInterner<'tcx>>,
+    E: TyEncoder<I = TyCtxt<'tcx>>,
     M: for<'b> Fn(&'b mut E) -> &'b mut FxHashMap<T, usize>,
     T: EncodableWithShorthand<E>,
     // The discriminant and shorthand must have the same size.
@@ -114,13 +112,13 @@ pub fn encode_with_shorthand<'tcx, E, T, M>(
     Ok(())
 }
 
-impl<'tcx, E: TyEncoder<I = TyInterner<'tcx>>> Encodable<E> for Ty<'tcx> {
+impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for Ty<'tcx> {
     fn encode(&self, e: &mut E) -> Result<(), E::Error> {
         encode_with_shorthand(e, self, TyEncoder::type_shorthands)
     }
 }
 
-impl<'tcx, E: TyEncoder<I = TyInterner<'tcx>>> Encodable<E>
+impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E>
     for ty::Binder<'tcx, ty::PredicateKind<'tcx>>
 {
     fn encode(&self, e: &mut E) -> Result<(), E::Error> {
@@ -129,37 +127,37 @@ fn encode(&self, e: &mut E) -> Result<(), E::Error> {
     }
 }
 
-impl<'tcx, E: TyEncoder<I = TyInterner<'tcx>>> Encodable<E> for ty::Predicate<'tcx> {
+impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for ty::Predicate<'tcx> {
     fn encode(&self, e: &mut E) -> Result<(), E::Error> {
         self.kind().encode(e)
     }
 }
 
-impl<'tcx, E: TyEncoder<I = TyInterner<'tcx>>> Encodable<E> for ty::Region<'tcx> {
+impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for ty::Region<'tcx> {
     fn encode(&self, e: &mut E) -> Result<(), E::Error> {
         self.kind().encode(e)
     }
 }
 
-impl<'tcx, E: TyEncoder<I = TyInterner<'tcx>>> Encodable<E> for ty::Const<'tcx> {
+impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for ty::Const<'tcx> {
     fn encode(&self, e: &mut E) -> Result<(), E::Error> {
         self.0.0.encode(e)
     }
 }
 
-impl<'tcx, E: TyEncoder<I = TyInterner<'tcx>>> Encodable<E> for ConstAllocation<'tcx> {
+impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for ConstAllocation<'tcx> {
     fn encode(&self, e: &mut E) -> Result<(), E::Error> {
         self.inner().encode(e)
     }
 }
 
-impl<'tcx, E: TyEncoder<I = TyInterner<'tcx>>> Encodable<E> for AdtDef<'tcx> {
+impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for AdtDef<'tcx> {
     fn encode(&self, e: &mut E) -> Result<(), E::Error> {
         self.0.0.encode(e)
     }
 }
 
-impl<'tcx, E: TyEncoder<I = TyInterner<'tcx>>> Encodable<E> for AllocId {
+impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for AllocId {
     fn encode(&self, e: &mut E) -> Result<(), E::Error> {
         e.encode_alloc_id(self)
     }
@@ -168,7 +166,7 @@ fn encode(&self, e: &mut E) -> Result<(), E::Error> {
 #[inline]
 fn decode_arena_allocable<
     'tcx,
-    D: TyDecoder<I = TyInterner<'tcx>>,
+    D: TyDecoder<I = TyCtxt<'tcx>>,
     T: ArenaAllocatable<'tcx> + Decodable<D>,
 >(
     decoder: &mut D,
@@ -176,13 +174,13 @@ fn decode_arena_allocable<
 where
     D: TyDecoder,
 {
-    decoder.interner().tcx.arena.alloc(Decodable::decode(decoder))
+    decoder.interner().arena.alloc(Decodable::decode(decoder))
 }
 
 #[inline]
 fn decode_arena_allocable_slice<
     'tcx,
-    D: TyDecoder<I = TyInterner<'tcx>>,
+    D: TyDecoder<I = TyCtxt<'tcx>>,
     T: ArenaAllocatable<'tcx> + Decodable<D>,
 >(
     decoder: &mut D,
@@ -190,10 +188,10 @@ fn decode_arena_allocable_slice<
 where
     D: TyDecoder,
 {
-    decoder.interner().tcx.arena.alloc_from_iter(<Vec<T> as Decodable<D>>::decode(decoder))
+    decoder.interner().arena.alloc_from_iter(<Vec<T> as Decodable<D>>::decode(decoder))
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> Decodable<D> for Ty<'tcx> {
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for Ty<'tcx> {
     #[allow(rustc::usage_of_ty_tykind)]
     fn decode(decoder: &mut D) -> Ty<'tcx> {
         // Handle shorthands first, if we have a usize > 0x80.
@@ -206,13 +204,13 @@ fn decode(decoder: &mut D) -> Ty<'tcx> {
                 decoder.with_position(shorthand, Ty::decode)
             })
         } else {
-            let tcx = decoder.interner().tcx;
+            let tcx = decoder.interner();
             tcx.mk_ty(rustc_type_ir::TyKind::decode(decoder))
         }
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> Decodable<D>
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D>
     for ty::Binder<'tcx, ty::PredicateKind<'tcx>>
 {
     fn decode(decoder: &mut D) -> ty::Binder<'tcx, ty::PredicateKind<'tcx>> {
@@ -233,64 +231,64 @@ fn decode(decoder: &mut D) -> ty::Binder<'tcx, ty::PredicateKind<'tcx>> {
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> Decodable<D> for ty::Predicate<'tcx> {
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for ty::Predicate<'tcx> {
     fn decode(decoder: &mut D) -> ty::Predicate<'tcx> {
         let predicate_kind = Decodable::decode(decoder);
-        decoder.interner().tcx.mk_predicate(predicate_kind)
+        decoder.interner().mk_predicate(predicate_kind)
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> Decodable<D> for SubstsRef<'tcx> {
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for SubstsRef<'tcx> {
     fn decode(decoder: &mut D) -> Self {
         let len = decoder.read_usize();
-        let tcx = decoder.interner().tcx;
+        let tcx = decoder.interner();
         tcx.mk_substs(
             (0..len).map::<ty::subst::GenericArg<'tcx>, _>(|_| Decodable::decode(decoder)),
         )
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> Decodable<D> for mir::Place<'tcx> {
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for mir::Place<'tcx> {
     fn decode(decoder: &mut D) -> Self {
         let local: mir::Local = Decodable::decode(decoder);
         let len = decoder.read_usize();
-        let projection = decoder.interner().tcx.mk_place_elems(
+        let projection = decoder.interner().mk_place_elems(
             (0..len).map::<mir::PlaceElem<'tcx>, _>(|_| Decodable::decode(decoder)),
         );
         mir::Place { local, projection }
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> Decodable<D> for ty::Region<'tcx> {
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for ty::Region<'tcx> {
     fn decode(decoder: &mut D) -> Self {
-        decoder.interner().tcx.mk_region(Decodable::decode(decoder))
+        decoder.interner().mk_region(Decodable::decode(decoder))
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> Decodable<D> for CanonicalVarInfos<'tcx> {
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for CanonicalVarInfos<'tcx> {
     fn decode(decoder: &mut D) -> Self {
         let len = decoder.read_usize();
         let interned: Vec<CanonicalVarInfo<'tcx>> =
             (0..len).map(|_| Decodable::decode(decoder)).collect();
-        decoder.interner().tcx.intern_canonical_var_infos(interned.as_slice())
+        decoder.interner().intern_canonical_var_infos(interned.as_slice())
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> Decodable<D> for AllocId {
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for AllocId {
     fn decode(decoder: &mut D) -> Self {
         decoder.decode_alloc_id()
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> Decodable<D> for ty::SymbolName<'tcx> {
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for ty::SymbolName<'tcx> {
     fn decode(decoder: &mut D) -> Self {
-        ty::SymbolName::new(decoder.interner().tcx, &decoder.read_str())
+        ty::SymbolName::new(decoder.interner(), &decoder.read_str())
     }
 }
 
 macro_rules! impl_decodable_via_ref {
     ($($t:ty),+) => {
-        $(impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> Decodable<D> for $t {
+        $(impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for $t {
             fn decode(decoder: &mut D) -> Self {
                 RefDecodable::decode(decoder)
             }
@@ -298,89 +296,86 @@ fn decode(decoder: &mut D) -> Self {
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> RefDecodable<'tcx, D> for ty::List<Ty<'tcx>> {
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D> for ty::List<Ty<'tcx>> {
     fn decode(decoder: &mut D) -> &'tcx Self {
         let len = decoder.read_usize();
-        decoder
-            .interner()
-            .tcx
-            .mk_type_list((0..len).map::<Ty<'tcx>, _>(|_| Decodable::decode(decoder)))
+        decoder.interner().mk_type_list((0..len).map::<Ty<'tcx>, _>(|_| Decodable::decode(decoder)))
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> RefDecodable<'tcx, D>
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D>
     for ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>
 {
     fn decode(decoder: &mut D) -> &'tcx Self {
         let len = decoder.read_usize();
-        decoder.interner().tcx.mk_poly_existential_predicates(
+        decoder.interner().mk_poly_existential_predicates(
             (0..len).map::<ty::Binder<'tcx, _>, _>(|_| Decodable::decode(decoder)),
         )
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> Decodable<D> for ty::Const<'tcx> {
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for ty::Const<'tcx> {
     fn decode(decoder: &mut D) -> Self {
-        decoder.interner().tcx.mk_const(Decodable::decode(decoder))
+        decoder.interner().mk_const(Decodable::decode(decoder))
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> RefDecodable<'tcx, D> for [ty::ValTree<'tcx>] {
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D> for [ty::ValTree<'tcx>] {
     fn decode(decoder: &mut D) -> &'tcx Self {
-        decoder.interner().tcx.arena.alloc_from_iter(
+        decoder.interner().arena.alloc_from_iter(
             (0..decoder.read_usize()).map(|_| Decodable::decode(decoder)).collect::<Vec<_>>(),
         )
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> Decodable<D> for ConstAllocation<'tcx> {
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for ConstAllocation<'tcx> {
     fn decode(decoder: &mut D) -> Self {
-        decoder.interner().tcx.intern_const_alloc(Decodable::decode(decoder))
+        decoder.interner().intern_const_alloc(Decodable::decode(decoder))
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> Decodable<D> for AdtDef<'tcx> {
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for AdtDef<'tcx> {
     fn decode(decoder: &mut D) -> Self {
-        decoder.interner().tcx.intern_adt_def(Decodable::decode(decoder))
+        decoder.interner().intern_adt_def(Decodable::decode(decoder))
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> RefDecodable<'tcx, D>
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D>
     for [(ty::Predicate<'tcx>, Span)]
 {
     fn decode(decoder: &mut D) -> &'tcx Self {
-        decoder.interner().tcx.arena.alloc_from_iter(
+        decoder.interner().arena.alloc_from_iter(
             (0..decoder.read_usize()).map(|_| Decodable::decode(decoder)).collect::<Vec<_>>(),
         )
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> RefDecodable<'tcx, D>
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D>
     for [thir::abstract_const::Node<'tcx>]
 {
     fn decode(decoder: &mut D) -> &'tcx Self {
-        decoder.interner().tcx.arena.alloc_from_iter(
+        decoder.interner().arena.alloc_from_iter(
             (0..decoder.read_usize()).map(|_| Decodable::decode(decoder)).collect::<Vec<_>>(),
         )
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> RefDecodable<'tcx, D>
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D>
     for [thir::abstract_const::NodeId]
 {
     fn decode(decoder: &mut D) -> &'tcx Self {
-        decoder.interner().tcx.arena.alloc_from_iter(
+        decoder.interner().arena.alloc_from_iter(
             (0..decoder.read_usize()).map(|_| Decodable::decode(decoder)).collect::<Vec<_>>(),
         )
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> RefDecodable<'tcx, D>
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D>
     for ty::List<ty::BoundVariableKind>
 {
     fn decode(decoder: &mut D) -> &'tcx Self {
         let len = decoder.read_usize();
-        decoder.interner().tcx.mk_bound_variable_kinds(
+        decoder.interner().mk_bound_variable_kinds(
             (0..len).map::<ty::BoundVariableKind, _>(|_| Decodable::decode(decoder)),
         )
     }
@@ -414,14 +409,14 @@ macro_rules! impl_arena_allocatable_decoder {
     ([]$args:tt) => {};
     ([decode $(, $attrs:ident)*]
      [$name:ident: $ty:ty]) => {
-        impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> RefDecodable<'tcx, D> for $ty {
+        impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D> for $ty {
             #[inline]
             fn decode(decoder: &mut D) -> &'tcx Self {
                 decode_arena_allocable(decoder)
             }
         }
 
-        impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> RefDecodable<'tcx, D> for [$ty] {
+        impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D> for [$ty] {
             #[inline]
             fn decode(decoder: &mut D) -> &'tcx Self {
                 decode_arena_allocable_slice(decoder)
@@ -443,17 +438,17 @@ macro_rules! impl_arena_allocatable_decoders {
 
 macro_rules! impl_arena_copy_decoder {
     (<$tcx:tt> $($ty:ty,)*) => {
-        $(impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> RefDecodable<'tcx, D> for $ty {
+        $(impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D> for $ty {
             #[inline]
             fn decode(decoder: &mut D) -> &'tcx Self {
-                decoder.interner().tcx.arena.alloc(Decodable::decode(decoder))
+                decoder.interner().arena.alloc(Decodable::decode(decoder))
             }
         }
 
-        impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> RefDecodable<'tcx, D> for [$ty] {
+        impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> RefDecodable<'tcx, D> for [$ty] {
             #[inline]
             fn decode(decoder: &mut D) -> &'tcx Self {
-                decoder.interner().tcx.arena.alloc_from_iter(<Vec<_> as Decodable<D>>::decode(decoder))
+                decoder.interner().arena.alloc_from_iter(<Vec<_> as Decodable<D>>::decode(decoder))
             }
         })*
     };
@@ -512,13 +507,13 @@ fn read_raw_bytes(&mut self, len: usize) -> &[u8] {
 macro_rules! impl_binder_encode_decode {
     ($($t:ty),+ $(,)?) => {
         $(
-            impl<'tcx, E: TyEncoder<I = TyInterner<'tcx>>> Encodable<E> for ty::Binder<'tcx, $t> {
+            impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for ty::Binder<'tcx, $t> {
                 fn encode(&self, e: &mut E) -> Result<(), E::Error> {
                     self.bound_vars().encode(e)?;
                     self.as_ref().skip_binder().encode(e)
                 }
             }
-            impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> Decodable<D> for ty::Binder<'tcx, $t> {
+            impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for ty::Binder<'tcx, $t> {
                 fn decode(decoder: &mut D) -> Self {
                     let bound_vars = Decodable::decode(decoder);
                     ty::Binder::bind_with_vars(Decodable::decode(decoder), bound_vars)
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index c1c7e1389cb..a0d92e2a5dd 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -90,12 +90,8 @@ fn new_empty(source_map: &'tcx SourceMap) -> Self
     fn serialize(&self, tcx: TyCtxt<'tcx>, encoder: &mut FileEncoder) -> FileEncodeResult;
 }
 
-pub struct TyInterner<'tcx> {
-    pub tcx: TyCtxt<'tcx>,
-}
-
 #[allow(rustc::usage_of_ty_tykind)]
-impl<'tcx> Interner for TyInterner<'tcx> {
+impl<'tcx> Interner for TyCtxt<'tcx> {
     type AdtDef = ty::AdtDef<'tcx>;
     type SubstsRef = ty::SubstsRef<'tcx>;
     type DefId = DefId;
@@ -1103,11 +1099,6 @@ pub struct GlobalCtxt<'tcx> {
 }
 
 impl<'tcx> TyCtxt<'tcx> {
-    #[inline]
-    pub fn interner(self) -> TyInterner<'tcx> {
-        TyInterner { tcx: self }
-    }
-
     /// Expects a body and returns its codegen attributes.
     ///
     /// Unlike `codegen_fn_attrs`, this returns `CodegenFnAttrs::EMPTY` for
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 03e8a9cb96c..14e5dc0dd77 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -68,8 +68,8 @@
 pub use self::context::{
     tls, CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,
     CtxtInterners, DelaySpanBugEmitted, FreeRegionInfo, GeneratorDiagnosticData,
-    GeneratorInteriorTypeCause, GlobalCtxt, Lift, OnDiskCache, TyCtxt, TyInterner, TypeckResults,
-    UserType, UserTypeAnnotationIndex,
+    GeneratorInteriorTypeCause, GlobalCtxt, Lift, OnDiskCache, TyCtxt, TypeckResults, UserType,
+    UserTypeAnnotationIndex,
 };
 pub use self::instance::{Instance, InstanceDef};
 pub use self::list::List;
@@ -463,30 +463,17 @@ pub(crate) struct TyS<'tcx> {
 #[rustc_pass_by_value]
 pub struct Ty<'tcx>(Interned<'tcx, WithStableHash<TyS<'tcx>>>);
 
-static LEAKED_BOOL_TY_ALREADY: std::sync::atomic::AtomicBool =
-    std::sync::atomic::AtomicBool::new(false);
-
-/// "Static" bool only used for internal testing.
-///
-/// FIXME(rustc_type_ir): This really should be replaced with something that doesn't leak.
-/// however, since it's used for testing, it's not _that_ bad.
-pub fn leak_bool_ty_for_unit_testing<'tcx>() -> Ty<'tcx> {
-    use std::sync::atomic::*;
-
-    if LEAKED_BOOL_TY_ALREADY.load(Ordering::Acquire) {
-        panic!("Can only leak one bool type, since its equality depends on its address");
-    } else {
-        LEAKED_BOOL_TY_ALREADY.store(true, Ordering::Release);
-    }
-
-    Ty(Interned::new_unchecked(Box::leak(Box::new(WithStableHash {
+impl<'tcx> TyCtxt<'tcx> {
+    /// A "bool" type used in rustc_mir_transform unit tests when we
+    /// have not spun up a TyCtxt.
+    pub const BOOL_TY_FOR_UNIT_TESTING: Ty<'tcx> = Ty(Interned::new_unchecked(&WithStableHash {
         internee: TyS {
             kind: ty::Bool,
             flags: TypeFlags::empty(),
             outer_exclusive_binder: DebruijnIndex::from_usize(0),
         },
         stable_hash: Fingerprint::ZERO,
-    }))))
+    }));
 }
 
 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TyS<'tcx> {
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index 9410166ac20..faeb729c884 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -32,7 +32,7 @@
 
 // Re-export the `TyKind` from `rustc_type_ir` here for convenience
 #[rustc_diagnostic_item = "TyKind"]
-pub type TyKind<'tcx> = IrTyKind<ty::TyInterner<'tcx>>;
+pub type TyKind<'tcx> = IrTyKind<TyCtxt<'tcx>>;
 
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
 #[derive(HashStable, TypeFoldable, Lift)]
diff --git a/compiler/rustc_middle/src/ty/subst.rs b/compiler/rustc_middle/src/ty/subst.rs
index 8494d5c71fe..290485ab5fe 100644
--- a/compiler/rustc_middle/src/ty/subst.rs
+++ b/compiler/rustc_middle/src/ty/subst.rs
@@ -4,7 +4,7 @@
 use crate::ty::codec::{TyDecoder, TyEncoder};
 use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder, TypeVisitor};
 use crate::ty::sty::{ClosureSubsts, GeneratorSubsts, InlineConstSubsts};
-use crate::ty::{self, Lift, List, ParamConst, Ty, TyCtxt, TyInterner};
+use crate::ty::{self, Lift, List, ParamConst, Ty, TyCtxt};
 
 use rustc_data_structures::intern::{Interned, WithStableHash};
 use rustc_hir::def_id::DefId;
@@ -216,13 +216,13 @@ fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow
     }
 }
 
-impl<'tcx, E: TyEncoder<I = TyInterner<'tcx>>> Encodable<E> for GenericArg<'tcx> {
+impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for GenericArg<'tcx> {
     fn encode(&self, e: &mut E) -> Result<(), E::Error> {
         self.unpack().encode(e)
     }
 }
 
-impl<'tcx, D: TyDecoder<I = TyInterner<'tcx>>> Decodable<D> for GenericArg<'tcx> {
+impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for GenericArg<'tcx> {
     fn decode(d: &mut D) -> GenericArg<'tcx> {
         GenericArgKind::decode(d).pack()
     }
diff --git a/compiler/rustc_mir_transform/src/coverage/tests.rs b/compiler/rustc_mir_transform/src/coverage/tests.rs
index 41f004b0c00..213bb6608e1 100644
--- a/compiler/rustc_mir_transform/src/coverage/tests.rs
+++ b/compiler/rustc_mir_transform/src/coverage/tests.rs
@@ -37,7 +37,7 @@
 use rustc_index::vec::{Idx, IndexVec};
 use rustc_middle::mir::coverage::CoverageKind;
 use rustc_middle::mir::*;
-use rustc_middle::ty::{self, Ty};
+use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::{self, BytePos, Pos, Span, DUMMY_SP};
 
 // All `TEMP_BLOCK` targets should be replaced before calling `to_body() -> mir::Body`.
@@ -56,7 +56,7 @@ fn new() -> Self {
             blocks: IndexVec::new(),
             dummy_place: Place { local: RETURN_PLACE, projection: ty::List::empty() },
             next_local: 0,
-            bool_ty: ty::leak_bool_ty_for_unit_testing(),
+            bool_ty: TyCtxt::BOOL_TY_FOR_UNIT_TESTING,
         }
     }
 
diff --git a/compiler/rustc_query_impl/src/on_disk_cache.rs b/compiler/rustc_query_impl/src/on_disk_cache.rs
index 7dc6921a569..8e4b3269402 100644
--- a/compiler/rustc_query_impl/src/on_disk_cache.rs
+++ b/compiler/rustc_query_impl/src/on_disk_cache.rs
@@ -11,7 +11,7 @@
 use rustc_middle::mir::{self, interpret};
 use rustc_middle::thir;
 use rustc_middle::ty::codec::{RefDecodable, TyDecoder, TyEncoder};
-use rustc_middle::ty::{self, Ty, TyCtxt, TyInterner};
+use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_query_system::dep_graph::DepContext;
 use rustc_query_system::query::{QueryCache, QueryContext, QuerySideEffects};
 use rustc_serialize::{
@@ -548,12 +548,12 @@ fn decode_tagged<D, T, V>(decoder: &mut D, expected_tag: T) -> V
 }
 
 impl<'a, 'tcx> TyDecoder for CacheDecoder<'a, 'tcx> {
-    type I = TyInterner<'tcx>;
+    type I = TyCtxt<'tcx>;
     const CLEAR_CROSS_CRATE: bool = false;
 
     #[inline]
-    fn interner(&self) -> TyInterner<'tcx> {
-        TyInterner { tcx: self.tcx }
+    fn interner(&self) -> TyCtxt<'tcx> {
+        self.tcx
     }
 
     #[inline]
@@ -932,7 +932,7 @@ impl<'a, 'tcx, E> TyEncoder for CacheEncoder<'a, 'tcx, E>
 where
     E: 'a + OpaqueEncoder,
 {
-    type I = TyInterner<'tcx>;
+    type I = TyCtxt<'tcx>;
     const CLEAR_CROSS_CRATE: bool = false;
 
     fn position(&self) -> usize {
diff --git a/compiler/rustc_query_system/src/ich/mod.rs b/compiler/rustc_query_system/src/ich/mod.rs
index ddaac1c78a1..0a1c350b2db 100644
--- a/compiler/rustc_query_system/src/ich/mod.rs
+++ b/compiler/rustc_query_system/src/ich/mod.rs
@@ -1,7 +1,6 @@
 //! ICH - Incremental Compilation Hash
 
 pub use self::hcx::StableHashingContext;
-use rustc_data_structures::stable_hasher::HashStable;
 use rustc_span::symbol::{sym, Symbol};
 
 mod hcx;
@@ -18,124 +17,3 @@
     sym::rustc_partition_codegened,
     sym::rustc_expected_cgu_reuse,
 ];
-
-#[allow(rustc::usage_of_ty_tykind)]
-impl<'__ctx, I: rustc_type_ir::Interner> HashStable<StableHashingContext<'__ctx>>
-    for rustc_type_ir::TyKind<I>
-where
-    I::AdtDef: HashStable<StableHashingContext<'__ctx>>,
-    I::DefId: HashStable<StableHashingContext<'__ctx>>,
-    I::SubstsRef: HashStable<StableHashingContext<'__ctx>>,
-    I::Ty: HashStable<StableHashingContext<'__ctx>>,
-    I::Const: HashStable<StableHashingContext<'__ctx>>,
-    I::TypeAndMut: HashStable<StableHashingContext<'__ctx>>,
-    I::PolyFnSig: HashStable<StableHashingContext<'__ctx>>,
-    I::ListBinderExistentialPredicate: HashStable<StableHashingContext<'__ctx>>,
-    I::Region: HashStable<StableHashingContext<'__ctx>>,
-    I::Movability: HashStable<StableHashingContext<'__ctx>>,
-    I::Mutability: HashStable<StableHashingContext<'__ctx>>,
-    I::BinderListTy: HashStable<StableHashingContext<'__ctx>>,
-    I::ListTy: HashStable<StableHashingContext<'__ctx>>,
-    I::ProjectionTy: HashStable<StableHashingContext<'__ctx>>,
-    I::BoundTy: HashStable<StableHashingContext<'__ctx>>,
-    I::ParamTy: HashStable<StableHashingContext<'__ctx>>,
-    I::PlaceholderType: HashStable<StableHashingContext<'__ctx>>,
-    I::InferTy: HashStable<StableHashingContext<'__ctx>>,
-    I::DelaySpanBugEmitted: HashStable<StableHashingContext<'__ctx>>,
-{
-    #[inline]
-    fn hash_stable(
-        &self,
-        __hcx: &mut crate::ich::StableHashingContext<'__ctx>,
-        __hasher: &mut rustc_data_structures::stable_hasher::StableHasher,
-    ) {
-        std::mem::discriminant(self).hash_stable(__hcx, __hasher);
-        use rustc_type_ir::TyKind::*;
-        match self {
-            Bool => {}
-            Char => {}
-            Int(i) => {
-                i.hash_stable(__hcx, __hasher);
-            }
-            Uint(u) => {
-                u.hash_stable(__hcx, __hasher);
-            }
-            Float(f) => {
-                f.hash_stable(__hcx, __hasher);
-            }
-            Adt(adt, substs) => {
-                adt.hash_stable(__hcx, __hasher);
-                substs.hash_stable(__hcx, __hasher);
-            }
-            Foreign(def_id) => {
-                def_id.hash_stable(__hcx, __hasher);
-            }
-            Str => {}
-            Array(t, c) => {
-                t.hash_stable(__hcx, __hasher);
-                c.hash_stable(__hcx, __hasher);
-            }
-            Slice(t) => {
-                t.hash_stable(__hcx, __hasher);
-            }
-            RawPtr(tam) => {
-                tam.hash_stable(__hcx, __hasher);
-            }
-            Ref(r, t, m) => {
-                r.hash_stable(__hcx, __hasher);
-                t.hash_stable(__hcx, __hasher);
-                m.hash_stable(__hcx, __hasher);
-            }
-            FnDef(def_id, substs) => {
-                def_id.hash_stable(__hcx, __hasher);
-                substs.hash_stable(__hcx, __hasher);
-            }
-            FnPtr(polyfnsig) => {
-                polyfnsig.hash_stable(__hcx, __hasher);
-            }
-            Dynamic(l, r) => {
-                l.hash_stable(__hcx, __hasher);
-                r.hash_stable(__hcx, __hasher);
-            }
-            Closure(def_id, substs) => {
-                def_id.hash_stable(__hcx, __hasher);
-                substs.hash_stable(__hcx, __hasher);
-            }
-            Generator(def_id, substs, m) => {
-                def_id.hash_stable(__hcx, __hasher);
-                substs.hash_stable(__hcx, __hasher);
-                m.hash_stable(__hcx, __hasher);
-            }
-            GeneratorWitness(b) => {
-                b.hash_stable(__hcx, __hasher);
-            }
-            Never => {}
-            Tuple(substs) => {
-                substs.hash_stable(__hcx, __hasher);
-            }
-            Projection(p) => {
-                p.hash_stable(__hcx, __hasher);
-            }
-            Opaque(def_id, substs) => {
-                def_id.hash_stable(__hcx, __hasher);
-                substs.hash_stable(__hcx, __hasher);
-            }
-            Param(p) => {
-                p.hash_stable(__hcx, __hasher);
-            }
-            Bound(d, b) => {
-                d.hash_stable(__hcx, __hasher);
-                b.hash_stable(__hcx, __hasher);
-            }
-            Placeholder(p) => {
-                p.hash_stable(__hcx, __hasher);
-            }
-            Infer(i) => {
-                i.hash_stable(__hcx, __hasher);
-            }
-            Error(d) => {
-                d.hash_stable(__hcx, __hasher);
-            }
-        }
-    }
-}
diff --git a/compiler/rustc_type_ir/src/lib.rs b/compiler/rustc_type_ir/src/lib.rs
index 766875dd82b..6380001b57c 100644
--- a/compiler/rustc_type_ir/src/lib.rs
+++ b/compiler/rustc_type_ir/src/lib.rs
@@ -8,7 +8,6 @@
 
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::unify::{EqUnifyValue, UnifyKey};
-//use rustc_serialize::{Decodable, Encodable};
 use smallvec::SmallVec;
 use std::fmt;
 use std::fmt::Debug;
diff --git a/compiler/rustc_type_ir/src/sty.rs b/compiler/rustc_type_ir/src/sty.rs
index 33b3a273f44..650c3519b56 100644
--- a/compiler/rustc_type_ir/src/sty.rs
+++ b/compiler/rustc_type_ir/src/sty.rs
@@ -13,6 +13,7 @@
 
 use self::TyKind::*;
 
+use rustc_data_structures::stable_hasher::HashStable;
 use rustc_serialize::{Decodable, Encodable};
 
 /// Defines the kinds of types used by the type system.
@@ -198,7 +199,10 @@ pub fn is_primitive(&self) -> bool {
     }
 }
 
-fn discriminant<I: Interner>(value: &TyKind<I>) -> usize {
+// This is manually implemented for `TyKind` because `std::mem::discriminant`
+// returns an opaque value that is `PartialEq` but not `PartialOrd`
+#[inline]
+const fn discriminant<I: Interner>(value: &TyKind<I>) -> usize {
     match value {
         Bool => 0,
         Char => 1,
@@ -230,6 +234,7 @@ fn discriminant<I: Interner>(value: &TyKind<I>) -> usize {
     }
 }
 
+// This is manually implemented because a derive would require `I: Clone`
 impl<I: Interner> Clone for TyKind<I> {
     fn clone(&self) -> Self {
         match self {
@@ -264,6 +269,7 @@ fn clone(&self) -> Self {
     }
 }
 
+// This is manually implemented because a derive would require `I: PartialEq`
 impl<I: Interner> PartialEq for TyKind<I> {
     #[inline]
     fn eq(&self, other: &TyKind<I>) -> bool {
@@ -324,8 +330,10 @@ fn eq(&self, other: &TyKind<I>) -> bool {
     }
 }
 
+// This is manually implemented because a derive would require `I: Eq`
 impl<I: Interner> Eq for TyKind<I> {}
 
+// This is manually implemented because a derive would require `I: PartialOrd`
 impl<I: Interner> PartialOrd for TyKind<I> {
     #[inline]
     fn partial_cmp(&self, other: &TyKind<I>) -> Option<Ordering> {
@@ -333,6 +341,7 @@ fn partial_cmp(&self, other: &TyKind<I>) -> Option<Ordering> {
     }
 }
 
+// This is manually implemented because a derive would require `I: Ord`
 impl<I: Interner> Ord for TyKind<I> {
     #[inline]
     fn cmp(&self, other: &TyKind<I>) -> Ordering {
@@ -430,6 +439,7 @@ fn cmp(&self, other: &TyKind<I>) -> Ordering {
     }
 }
 
+// This is manually implemented because a derive would require `I: Hash`
 impl<I: Interner> hash::Hash for TyKind<I> {
     fn hash<__H: hash::Hasher>(&self, state: &mut __H) -> () {
         match (&*self,) {
@@ -541,6 +551,7 @@ fn hash<__H: hash::Hasher>(&self, state: &mut __H) -> () {
     }
 }
 
+// This is manually implemented because a derive would require `I: Debug`
 impl<I: Interner> fmt::Debug for TyKind<I> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match (&*self,) {
@@ -678,6 +689,7 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     }
 }
 
+// This is manually implemented because a derive would require `I: Encodable`
 impl<I: Interner, E: TyEncoder> Encodable<E> for TyKind<I>
 where
     I::DelaySpanBugEmitted: Encodable<E>,
@@ -819,6 +831,7 @@ fn encode(&self, e: &mut E) -> Result<(), <E as rustc_serialize::Encoder>::Error
     }
 }
 
+// This is manually implemented because a derive would require `I: Decodable`
 impl<I: Interner, D: TyDecoder<I = I>> Decodable<D> for TyKind<I>
 where
     I::DelaySpanBugEmitted: Decodable<D>,
@@ -905,3 +918,123 @@ fn decode(d: &mut D) -> Self {
         }
     }
 }
+
+// This is not a derived impl because a derive would require `I: HashStable`
+#[allow(rustc::usage_of_ty_tykind)]
+impl<CTX, I: Interner> HashStable<CTX> for TyKind<I>
+where
+    I::AdtDef: HashStable<CTX>,
+    I::DefId: HashStable<CTX>,
+    I::SubstsRef: HashStable<CTX>,
+    I::Ty: HashStable<CTX>,
+    I::Const: HashStable<CTX>,
+    I::TypeAndMut: HashStable<CTX>,
+    I::PolyFnSig: HashStable<CTX>,
+    I::ListBinderExistentialPredicate: HashStable<CTX>,
+    I::Region: HashStable<CTX>,
+    I::Movability: HashStable<CTX>,
+    I::Mutability: HashStable<CTX>,
+    I::BinderListTy: HashStable<CTX>,
+    I::ListTy: HashStable<CTX>,
+    I::ProjectionTy: HashStable<CTX>,
+    I::BoundTy: HashStable<CTX>,
+    I::ParamTy: HashStable<CTX>,
+    I::PlaceholderType: HashStable<CTX>,
+    I::InferTy: HashStable<CTX>,
+    I::DelaySpanBugEmitted: HashStable<CTX>,
+{
+    #[inline]
+    fn hash_stable(
+        &self,
+        __hcx: &mut CTX,
+        __hasher: &mut rustc_data_structures::stable_hasher::StableHasher,
+    ) {
+        std::mem::discriminant(self).hash_stable(__hcx, __hasher);
+        match self {
+            Bool => {}
+            Char => {}
+            Int(i) => {
+                i.hash_stable(__hcx, __hasher);
+            }
+            Uint(u) => {
+                u.hash_stable(__hcx, __hasher);
+            }
+            Float(f) => {
+                f.hash_stable(__hcx, __hasher);
+            }
+            Adt(adt, substs) => {
+                adt.hash_stable(__hcx, __hasher);
+                substs.hash_stable(__hcx, __hasher);
+            }
+            Foreign(def_id) => {
+                def_id.hash_stable(__hcx, __hasher);
+            }
+            Str => {}
+            Array(t, c) => {
+                t.hash_stable(__hcx, __hasher);
+                c.hash_stable(__hcx, __hasher);
+            }
+            Slice(t) => {
+                t.hash_stable(__hcx, __hasher);
+            }
+            RawPtr(tam) => {
+                tam.hash_stable(__hcx, __hasher);
+            }
+            Ref(r, t, m) => {
+                r.hash_stable(__hcx, __hasher);
+                t.hash_stable(__hcx, __hasher);
+                m.hash_stable(__hcx, __hasher);
+            }
+            FnDef(def_id, substs) => {
+                def_id.hash_stable(__hcx, __hasher);
+                substs.hash_stable(__hcx, __hasher);
+            }
+            FnPtr(polyfnsig) => {
+                polyfnsig.hash_stable(__hcx, __hasher);
+            }
+            Dynamic(l, r) => {
+                l.hash_stable(__hcx, __hasher);
+                r.hash_stable(__hcx, __hasher);
+            }
+            Closure(def_id, substs) => {
+                def_id.hash_stable(__hcx, __hasher);
+                substs.hash_stable(__hcx, __hasher);
+            }
+            Generator(def_id, substs, m) => {
+                def_id.hash_stable(__hcx, __hasher);
+                substs.hash_stable(__hcx, __hasher);
+                m.hash_stable(__hcx, __hasher);
+            }
+            GeneratorWitness(b) => {
+                b.hash_stable(__hcx, __hasher);
+            }
+            Never => {}
+            Tuple(substs) => {
+                substs.hash_stable(__hcx, __hasher);
+            }
+            Projection(p) => {
+                p.hash_stable(__hcx, __hasher);
+            }
+            Opaque(def_id, substs) => {
+                def_id.hash_stable(__hcx, __hasher);
+                substs.hash_stable(__hcx, __hasher);
+            }
+            Param(p) => {
+                p.hash_stable(__hcx, __hasher);
+            }
+            Bound(d, b) => {
+                d.hash_stable(__hcx, __hasher);
+                b.hash_stable(__hcx, __hasher);
+            }
+            Placeholder(p) => {
+                p.hash_stable(__hcx, __hasher);
+            }
+            Infer(i) => {
+                i.hash_stable(__hcx, __hasher);
+            }
+            Error(d) => {
+                d.hash_stable(__hcx, __hasher);
+            }
+        }
+    }
+}
diff --git a/compiler/rustc_typeck/src/check/op.rs b/compiler/rustc_typeck/src/check/op.rs
index 6df9ac5f0a4..3ae04706e4b 100644
--- a/compiler/rustc_typeck/src/check/op.rs
+++ b/compiler/rustc_typeck/src/check/op.rs
@@ -677,8 +677,6 @@ pub fn check_user_unop(
         operand_ty: Ty<'tcx>,
         op: hir::UnOp,
     ) -> Ty<'tcx> {
-        use rustc_type_ir::sty::TyKind::*;
-
         assert!(op.is_by_value());
         match self.lookup_op_method(operand_ty, None, None, Op::Unary(op, ex.span)) {
             Ok(method) => {