Remove `CacheSelector` trait now that we can use GATs

5 files changed, 57 insertions, 102 deletions

diff --git a/compiler/rustc_middle/src/query/keys.rs b/compiler/rustc_middle/src/query/keys.rs
index 3b1d1a04d6f..9cbc4d10146 100644
--- a/compiler/rustc_middle/src/query/keys.rs
+++ b/compiler/rustc_middle/src/query/keys.rs
@@ -9,8 +9,7 @@ use crate::ty::{self, Ty, TyCtxt};
 use crate::ty::{GenericArg, GenericArgsRef};
 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LocalModDefId, ModDefId, LOCAL_CRATE};
 use rustc_hir::hir_id::{HirId, OwnerId};
-use rustc_query_system::query::DefIdCacheSelector;
-use rustc_query_system::query::{DefaultCacheSelector, SingleCacheSelector, VecCacheSelector};
+use rustc_query_system::query::{DefIdCache, DefaultCache, SingleCache, VecCache};
 use rustc_span::symbol::{Ident, Symbol};
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::abi;
@@ -22,7 +21,7 @@ pub struct LocalCrate;
 /// The `Key` trait controls what types can legally be used as the key
 /// for a query.
 pub trait Key: Sized {
-    // N.B. Most of the keys down below have `type CacheSelector = DefaultCacheSelector<Self>;`,
+    // N.B. Most of the keys down below have `type Cache<V> = DefaultCache<Self, V>;`,
     //      it would be reasonable to use associated type defaults, to remove the duplication...
     //
     //      ...But r-a doesn't support them yet and using a default here causes r-a to not infer
@@ -30,7 +29,7 @@ pub trait Key: Sized {
     //      type defaults, please restrain from using them here <3
     //
     //      r-a issue: <https://github.com/rust-lang/rust-analyzer/issues/13693>
-    type CacheSelector;
+    type Cache<V>;
 
     /// In the event that a cycle occurs, if no explicit span has been
     /// given for a query with key `self`, what span should we use?
@@ -56,7 +55,7 @@ pub trait AsLocalKey: Key {
 }
 
 impl Key for () {
-    type CacheSelector = SingleCacheSelector;
+    type Cache<V> = SingleCache<V>;
 
     fn default_span(&self, _: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -64,7 +63,7 @@ impl Key for () {
 }
 
 impl<'tcx> Key for ty::InstanceDef<'tcx> {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         tcx.def_span(self.def_id())
@@ -81,7 +80,7 @@ impl<'tcx> AsLocalKey for ty::InstanceDef<'tcx> {
 }
 
 impl<'tcx> Key for ty::Instance<'tcx> {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         tcx.def_span(self.def_id())
@@ -89,7 +88,7 @@ impl<'tcx> Key for ty::Instance<'tcx> {
 }
 
 impl<'tcx> Key for mir::interpret::GlobalId<'tcx> {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         self.instance.default_span(tcx)
@@ -97,7 +96,7 @@ impl<'tcx> Key for mir::interpret::GlobalId<'tcx> {
 }
 
 impl<'tcx> Key for (Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -105,7 +104,7 @@ impl<'tcx> Key for (Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>) {
 }
 
 impl<'tcx> Key for mir::interpret::LitToConstInput<'tcx> {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -113,7 +112,7 @@ impl<'tcx> Key for mir::interpret::LitToConstInput<'tcx> {
 }
 
 impl Key for CrateNum {
-    type CacheSelector = VecCacheSelector<Self>;
+    type Cache<V> = VecCache<Self, V>;
 
     fn default_span(&self, _: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -130,7 +129,7 @@ impl AsLocalKey for CrateNum {
 }
 
 impl Key for OwnerId {
-    type CacheSelector = VecCacheSelector<Self>;
+    type Cache<V> = VecCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         self.to_def_id().default_span(tcx)
@@ -142,7 +141,7 @@ impl Key for OwnerId {
 }
 
 impl Key for LocalDefId {
-    type CacheSelector = VecCacheSelector<Self>;
+    type Cache<V> = VecCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         self.to_def_id().default_span(tcx)
@@ -154,7 +153,7 @@ impl Key for LocalDefId {
 }
 
 impl Key for DefId {
-    type CacheSelector = DefIdCacheSelector;
+    type Cache<V> = DefIdCache<V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         tcx.def_span(*self)
@@ -176,7 +175,7 @@ impl AsLocalKey for DefId {
 }
 
 impl Key for LocalModDefId {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         tcx.def_span(*self)
@@ -189,7 +188,7 @@ impl Key for LocalModDefId {
 }
 
 impl Key for ModDefId {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         tcx.def_span(*self)
@@ -211,7 +210,7 @@ impl AsLocalKey for ModDefId {
 }
 
 impl Key for SimplifiedType {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -219,7 +218,7 @@ impl Key for SimplifiedType {
 }
 
 impl Key for (DefId, DefId) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         self.1.default_span(tcx)
@@ -227,7 +226,7 @@ impl Key for (DefId, DefId) {
 }
 
 impl<'tcx> Key for (ty::Instance<'tcx>, LocalDefId) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         self.0.default_span(tcx)
@@ -235,7 +234,7 @@ impl<'tcx> Key for (ty::Instance<'tcx>, LocalDefId) {
 }
 
 impl Key for (DefId, LocalDefId) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         self.1.default_span(tcx)
@@ -243,7 +242,7 @@ impl Key for (DefId, LocalDefId) {
 }
 
 impl Key for (LocalDefId, DefId) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         self.0.default_span(tcx)
@@ -251,7 +250,7 @@ impl Key for (LocalDefId, DefId) {
 }
 
 impl Key for (LocalDefId, LocalDefId) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         self.0.default_span(tcx)
@@ -259,7 +258,7 @@ impl Key for (LocalDefId, LocalDefId) {
 }
 
 impl Key for (DefId, Ident) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         tcx.def_span(self.0)
@@ -272,7 +271,7 @@ impl Key for (DefId, Ident) {
 }
 
 impl Key for (LocalDefId, LocalDefId, Ident) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         self.1.default_span(tcx)
@@ -280,7 +279,7 @@ impl Key for (LocalDefId, LocalDefId, Ident) {
 }
 
 impl Key for (CrateNum, DefId) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         self.1.default_span(tcx)
@@ -297,7 +296,7 @@ impl AsLocalKey for (CrateNum, DefId) {
 }
 
 impl Key for (CrateNum, SimplifiedType) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -314,7 +313,7 @@ impl AsLocalKey for (CrateNum, SimplifiedType) {
 }
 
 impl Key for (DefId, SimplifiedType) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         self.0.default_span(tcx)
@@ -322,7 +321,7 @@ impl Key for (DefId, SimplifiedType) {
 }
 
 impl<'tcx> Key for GenericArgsRef<'tcx> {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -330,7 +329,7 @@ impl<'tcx> Key for GenericArgsRef<'tcx> {
 }
 
 impl<'tcx> Key for (DefId, GenericArgsRef<'tcx>) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         self.0.default_span(tcx)
@@ -338,7 +337,7 @@ impl<'tcx> Key for (DefId, GenericArgsRef<'tcx>) {
 }
 
 impl<'tcx> Key for (ty::UnevaluatedConst<'tcx>, ty::UnevaluatedConst<'tcx>) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         (self.0).def.default_span(tcx)
@@ -346,7 +345,7 @@ impl<'tcx> Key for (ty::UnevaluatedConst<'tcx>, ty::UnevaluatedConst<'tcx>) {
 }
 
 impl<'tcx> Key for (LocalDefId, DefId, GenericArgsRef<'tcx>) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         self.0.default_span(tcx)
@@ -354,7 +353,7 @@ impl<'tcx> Key for (LocalDefId, DefId, GenericArgsRef<'tcx>) {
 }
 
 impl<'tcx> Key for (ty::ParamEnv<'tcx>, ty::TraitRef<'tcx>) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         tcx.def_span(self.1.def_id)
@@ -362,7 +361,7 @@ impl<'tcx> Key for (ty::ParamEnv<'tcx>, ty::TraitRef<'tcx>) {
 }
 
 impl<'tcx> Key for ty::PolyTraitRef<'tcx> {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         tcx.def_span(self.def_id())
@@ -370,7 +369,7 @@ impl<'tcx> Key for ty::PolyTraitRef<'tcx> {
 }
 
 impl<'tcx> Key for ty::PolyExistentialTraitRef<'tcx> {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         tcx.def_span(self.def_id())
@@ -378,7 +377,7 @@ impl<'tcx> Key for ty::PolyExistentialTraitRef<'tcx> {
 }
 
 impl<'tcx> Key for (ty::PolyTraitRef<'tcx>, ty::PolyTraitRef<'tcx>) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         tcx.def_span(self.0.def_id())
@@ -386,7 +385,7 @@ impl<'tcx> Key for (ty::PolyTraitRef<'tcx>, ty::PolyTraitRef<'tcx>) {
 }
 
 impl<'tcx> Key for GenericArg<'tcx> {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -394,7 +393,7 @@ impl<'tcx> Key for GenericArg<'tcx> {
 }
 
 impl<'tcx> Key for ty::Const<'tcx> {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -402,7 +401,7 @@ impl<'tcx> Key for ty::Const<'tcx> {
 }
 
 impl<'tcx> Key for Ty<'tcx> {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -418,7 +417,7 @@ impl<'tcx> Key for Ty<'tcx> {
 }
 
 impl<'tcx> Key for TyAndLayout<'tcx> {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -426,7 +425,7 @@ impl<'tcx> Key for TyAndLayout<'tcx> {
 }
 
 impl<'tcx> Key for (Ty<'tcx>, Ty<'tcx>) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -434,7 +433,7 @@ impl<'tcx> Key for (Ty<'tcx>, Ty<'tcx>) {
 }
 
 impl<'tcx> Key for &'tcx ty::List<ty::Clause<'tcx>> {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -442,7 +441,7 @@ impl<'tcx> Key for &'tcx ty::List<ty::Clause<'tcx>> {
 }
 
 impl<'tcx> Key for ty::ParamEnv<'tcx> {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -450,7 +449,7 @@ impl<'tcx> Key for ty::ParamEnv<'tcx> {
 }
 
 impl<'tcx, T: Key> Key for ty::ParamEnvAnd<'tcx, T> {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         self.value.default_span(tcx)
@@ -462,7 +461,7 @@ impl<'tcx, T: Key> Key for ty::ParamEnvAnd<'tcx, T> {
 }
 
 impl Key for Symbol {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -470,7 +469,7 @@ impl Key for Symbol {
 }
 
 impl Key for Option<Symbol> {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -480,7 +479,7 @@ impl Key for Option<Symbol> {
 /// Canonical query goals correspond to abstract trait operations that
 /// are not tied to any crate in particular.
 impl<'tcx, T: Clone> Key for Canonical<'tcx, T> {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -488,7 +487,7 @@ impl<'tcx, T: Clone> Key for Canonical<'tcx, T> {
 }
 
 impl Key for (Symbol, u32, u32) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -496,7 +495,7 @@ impl Key for (Symbol, u32, u32) {
 }
 
 impl<'tcx> Key for (DefId, Ty<'tcx>, GenericArgsRef<'tcx>, ty::ParamEnv<'tcx>) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -504,7 +503,7 @@ impl<'tcx> Key for (DefId, Ty<'tcx>, GenericArgsRef<'tcx>, ty::ParamEnv<'tcx>) {
 }
 
 impl<'tcx> Key for (Ty<'tcx>, abi::VariantIdx) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -512,7 +511,7 @@ impl<'tcx> Key for (Ty<'tcx>, abi::VariantIdx) {
 }
 
 impl<'tcx> Key for (ty::Predicate<'tcx>, traits::WellFormedLoc) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -520,7 +519,7 @@ impl<'tcx> Key for (ty::Predicate<'tcx>, traits::WellFormedLoc) {
 }
 
 impl<'tcx> Key for (ty::PolyFnSig<'tcx>, &'tcx ty::List<Ty<'tcx>>) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -528,7 +527,7 @@ impl<'tcx> Key for (ty::PolyFnSig<'tcx>, &'tcx ty::List<Ty<'tcx>>) {
 }
 
 impl<'tcx> Key for (ty::Instance<'tcx>, &'tcx ty::List<Ty<'tcx>>) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         self.0.default_span(tcx)
@@ -536,7 +535,7 @@ impl<'tcx> Key for (ty::Instance<'tcx>, &'tcx ty::List<Ty<'tcx>>) {
 }
 
 impl<'tcx> Key for (Ty<'tcx>, ty::ValTree<'tcx>) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, _: TyCtxt<'_>) -> Span {
         DUMMY_SP
@@ -544,7 +543,7 @@ impl<'tcx> Key for (Ty<'tcx>, ty::ValTree<'tcx>) {
 }
 
 impl Key for HirId {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
         tcx.hir().span(*self)
@@ -557,7 +556,7 @@ impl Key for HirId {
 }
 
 impl<'tcx> Key for (ValidityRequirement, ty::ParamEnvAnd<'tcx, Ty<'tcx>>) {
-    type CacheSelector = DefaultCacheSelector<Self>;
+    type Cache<V> = DefaultCache<Self, V>;
 
     // Just forward to `Ty<'tcx>`
 
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 38cfd11a016..5e4454db3e2 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -73,7 +73,7 @@ use rustc_hir::lang_items::{LangItem, LanguageItems};
 use rustc_hir::{Crate, ItemLocalId, ItemLocalMap, TraitCandidate};
 use rustc_index::IndexVec;
 use rustc_query_system::ich::StableHashingContext;
-use rustc_query_system::query::{try_get_cached, CacheSelector, QueryCache, QueryMode, QueryState};
+use rustc_query_system::query::{try_get_cached, QueryCache, QueryMode, QueryState};
 use rustc_session::config::{EntryFnType, OptLevel, OutputFilenames, SymbolManglingVersion};
 use rustc_session::cstore::{CrateDepKind, CrateSource};
 use rustc_session::cstore::{ExternCrate, ForeignModule, LinkagePreference, NativeLib};
diff --git a/compiler/rustc_middle/src/query/plumbing.rs b/compiler/rustc_middle/src/query/plumbing.rs
index 8d88488e167..e3588a7afdc 100644
--- a/compiler/rustc_middle/src/query/plumbing.rs
+++ b/compiler/rustc_middle/src/query/plumbing.rs
@@ -336,9 +336,7 @@ macro_rules! define_callbacks {
                     ))
                 }
 
-                pub type Storage<'tcx> = <
-                    <$($K)* as keys::Key>::CacheSelector as CacheSelector<'tcx, Erase<$V>>
-                >::Cache;
+                pub type Storage<'tcx> = <$($K)* as keys::Key>::Cache<Erase<$V>>;
 
                 // Ensure that keys grow no larger than 64 bytes
                 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
diff --git a/compiler/rustc_query_system/src/query/caches.rs b/compiler/rustc_query_system/src/query/caches.rs
index 674a0984ae9..c3fc036aed3 100644
--- a/compiler/rustc_query_system/src/query/caches.rs
+++ b/compiler/rustc_query_system/src/query/caches.rs
@@ -9,13 +9,6 @@ use rustc_span::def_id::DefId;
 use rustc_span::def_id::DefIndex;
 use std::fmt::Debug;
 use std::hash::Hash;
-use std::marker::PhantomData;
-
-pub trait CacheSelector<'tcx, V> {
-    type Cache
-    where
-        V: Copy;
-}
 
 pub trait QueryCache: Sized {
     type Key: Hash + Eq + Copy + Debug;
@@ -29,14 +22,6 @@ pub trait QueryCache: Sized {
     fn iter(&self, f: &mut dyn FnMut(&Self::Key, &Self::Value, DepNodeIndex));
 }
 
-pub struct DefaultCacheSelector<K>(PhantomData<K>);
-
-impl<'tcx, K: Eq + Hash, V: 'tcx> CacheSelector<'tcx, V> for DefaultCacheSelector<K> {
-    type Cache = DefaultCache<K, V>
-    where
-        V: Copy;
-}
-
 pub struct DefaultCache<K, V> {
     cache: Sharded<FxHashMap<K, (V, DepNodeIndex)>>,
 }
@@ -81,14 +66,6 @@ where
     }
 }
 
-pub struct SingleCacheSelector;
-
-impl<'tcx, V: 'tcx> CacheSelector<'tcx, V> for SingleCacheSelector {
-    type Cache = SingleCache<V>
-    where
-        V: Copy;
-}
-
 pub struct SingleCache<V> {
     cache: OnceLock<(V, DepNodeIndex)>,
 }
@@ -123,14 +100,6 @@ where
     }
 }
 
-pub struct VecCacheSelector<K>(PhantomData<K>);
-
-impl<'tcx, K: Idx, V: 'tcx> CacheSelector<'tcx, V> for VecCacheSelector<K> {
-    type Cache = VecCache<K, V>
-    where
-        V: Copy;
-}
-
 pub struct VecCache<K: Idx, V> {
     cache: Sharded<IndexVec<K, Option<(V, DepNodeIndex)>>>,
 }
@@ -174,14 +143,6 @@ where
     }
 }
 
-pub struct DefIdCacheSelector;
-
-impl<'tcx, V: 'tcx> CacheSelector<'tcx, V> for DefIdCacheSelector {
-    type Cache = DefIdCache<V>
-    where
-        V: Copy;
-}
-
 pub struct DefIdCache<V> {
     /// Stores the local DefIds in a dense map. Local queries are much more often dense, so this is
     /// a win over hashing query keys at marginal memory cost (~5% at most) compared to FxHashMap.
diff --git a/compiler/rustc_query_system/src/query/mod.rs b/compiler/rustc_query_system/src/query/mod.rs
index 01b9d458f1e..91a0026f281 100644
--- a/compiler/rustc_query_system/src/query/mod.rs
+++ b/compiler/rustc_query_system/src/query/mod.rs
@@ -9,10 +9,7 @@ pub use self::job::{
 };
 
 mod caches;
-pub use self::caches::{
-    CacheSelector, DefIdCacheSelector, DefaultCacheSelector, QueryCache, SingleCacheSelector,
-    VecCacheSelector,
-};
+pub use self::caches::{DefIdCache, DefaultCache, QueryCache, SingleCache, VecCache};
 
 mod config;
 pub use self::config::{HashResult, QueryConfig};