1 files changed, 559 insertions, 0 deletions
diff --git a/compiler/rustc_middle/src/query/keys.rs b/compiler/rustc_middle/src/query/keys.rs
new file mode 100644
index 00000000000..11376345052
--- /dev/null
+++ b/compiler/rustc_middle/src/query/keys.rs
@@ -0,0 +1,559 @@
+//! Defines the set of legal keys that can be used in queries.
+
+use crate::infer::canonical::Canonical;
+use crate::mir;
+use crate::traits;
+use crate::ty::fast_reject::SimplifiedType;
+use crate::ty::layout::{TyAndLayout, ValidityRequirement};
+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::{DefaultCacheSelector, SingleCacheSelector, VecCacheSelector};
+use rustc_span::symbol::{Ident, Symbol};
+use rustc_span::{Span, DUMMY_SP};
+
+/// Placeholder for `CrateNum`'s "local" counterpart
+#[derive(Copy, Clone, Debug)]
+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>;`,
+    //      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
+    //      return types of queries which is very annoying. Thus, until r-a support associated
+    //      type defaults, please restrain from using them here <3
+    //
+    //      r-a issue: <https://github.com/rust-lang/rust-analyzer/issues/13693>
+    type CacheSelector;
+
+    /// 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?
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span;
+
+    /// If the key is a [`DefId`] or `DefId`--equivalent, return that `DefId`.
+    /// Otherwise, return `None`.
+    fn key_as_def_id(&self) -> Option<DefId> {
+        None
+    }
+
+    fn ty_adt_id(&self) -> Option<DefId> {
+        None
+    }
+}
+
+pub trait AsLocalKey: Key {
+    type LocalKey;
+
+    /// Given an instance of this key, what crate is it referring to?
+    /// This is used to find the provider.
+    fn as_local_key(&self) -> Option<Self::LocalKey>;
+}
+
+impl Key for () {
+    type CacheSelector = SingleCacheSelector;
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl<'tcx> Key for ty::InstanceDef<'tcx> {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        tcx.def_span(self.def_id())
+    }
+}
+
+impl<'tcx> AsLocalKey for ty::InstanceDef<'tcx> {
+    type LocalKey = Self;
+
+    #[inline(always)]
+    fn as_local_key(&self) -> Option<Self::LocalKey> {
+        self.def_id().is_local().then(|| *self)
+    }
+}
+
+impl<'tcx> Key for ty::Instance<'tcx> {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        tcx.def_span(self.def_id())
+    }
+}
+
+impl<'tcx> Key for mir::interpret::GlobalId<'tcx> {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        self.instance.default_span(tcx)
+    }
+}
+
+impl<'tcx> Key for (Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl<'tcx> Key for mir::interpret::LitToConstInput<'tcx> {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl Key for CrateNum {
+    type CacheSelector = VecCacheSelector<Self>;
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl AsLocalKey for CrateNum {
+    type LocalKey = LocalCrate;
+
+    #[inline(always)]
+    fn as_local_key(&self) -> Option<Self::LocalKey> {
+        (*self == LOCAL_CRATE).then_some(LocalCrate)
+    }
+}
+
+impl Key for OwnerId {
+    type CacheSelector = VecCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        self.to_def_id().default_span(tcx)
+    }
+
+    fn key_as_def_id(&self) -> Option<DefId> {
+        Some(self.to_def_id())
+    }
+}
+
+impl Key for LocalDefId {
+    type CacheSelector = VecCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        self.to_def_id().default_span(tcx)
+    }
+
+    fn key_as_def_id(&self) -> Option<DefId> {
+        Some(self.to_def_id())
+    }
+}
+
+impl Key for DefId {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        tcx.def_span(*self)
+    }
+
+    #[inline(always)]
+    fn key_as_def_id(&self) -> Option<DefId> {
+        Some(*self)
+    }
+}
+
+impl AsLocalKey for DefId {
+    type LocalKey = LocalDefId;
+
+    #[inline(always)]
+    fn as_local_key(&self) -> Option<Self::LocalKey> {
+        self.as_local()
+    }
+}
+
+impl Key for LocalModDefId {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        tcx.def_span(*self)
+    }
+
+    #[inline(always)]
+    fn key_as_def_id(&self) -> Option<DefId> {
+        Some(self.to_def_id())
+    }
+}
+
+impl Key for ModDefId {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        tcx.def_span(*self)
+    }
+
+    #[inline(always)]
+    fn key_as_def_id(&self) -> Option<DefId> {
+        Some(self.to_def_id())
+    }
+}
+
+impl AsLocalKey for ModDefId {
+    type LocalKey = LocalModDefId;
+
+    #[inline(always)]
+    fn as_local_key(&self) -> Option<Self::LocalKey> {
+        self.as_local()
+    }
+}
+
+impl Key for SimplifiedType {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl Key for (DefId, DefId) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        self.1.default_span(tcx)
+    }
+}
+
+impl<'tcx> Key for (ty::Instance<'tcx>, LocalDefId) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        self.0.default_span(tcx)
+    }
+}
+
+impl Key for (DefId, LocalDefId) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        self.1.default_span(tcx)
+    }
+}
+
+impl Key for (LocalDefId, DefId) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        self.0.default_span(tcx)
+    }
+}
+
+impl Key for (LocalDefId, LocalDefId) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        self.0.default_span(tcx)
+    }
+}
+
+impl Key for (DefId, Ident) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        tcx.def_span(self.0)
+    }
+
+    #[inline(always)]
+    fn key_as_def_id(&self) -> Option<DefId> {
+        Some(self.0)
+    }
+}
+
+impl Key for (LocalDefId, LocalDefId, Ident) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        self.1.default_span(tcx)
+    }
+}
+
+impl Key for (CrateNum, DefId) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        self.1.default_span(tcx)
+    }
+}
+
+impl AsLocalKey for (CrateNum, DefId) {
+    type LocalKey = DefId;
+
+    #[inline(always)]
+    fn as_local_key(&self) -> Option<Self::LocalKey> {
+        (self.0 == LOCAL_CRATE).then(|| self.1)
+    }
+}
+
+impl Key for (CrateNum, SimplifiedType) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl AsLocalKey for (CrateNum, SimplifiedType) {
+    type LocalKey = SimplifiedType;
+
+    #[inline(always)]
+    fn as_local_key(&self) -> Option<Self::LocalKey> {
+        (self.0 == LOCAL_CRATE).then(|| self.1)
+    }
+}
+
+impl Key for (DefId, SimplifiedType) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        self.0.default_span(tcx)
+    }
+}
+
+impl<'tcx> Key for GenericArgsRef<'tcx> {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl<'tcx> Key for (DefId, GenericArgsRef<'tcx>) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        self.0.default_span(tcx)
+    }
+}
+
+impl<'tcx> Key for (ty::UnevaluatedConst<'tcx>, ty::UnevaluatedConst<'tcx>) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        (self.0).def.default_span(tcx)
+    }
+}
+
+impl<'tcx> Key for (LocalDefId, DefId, GenericArgsRef<'tcx>) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        self.0.default_span(tcx)
+    }
+}
+
+impl<'tcx> Key for (ty::ParamEnv<'tcx>, ty::TraitRef<'tcx>) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        tcx.def_span(self.1.def_id)
+    }
+}
+
+impl<'tcx> Key for ty::PolyTraitRef<'tcx> {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        tcx.def_span(self.def_id())
+    }
+}
+
+impl<'tcx> Key for ty::PolyExistentialTraitRef<'tcx> {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        tcx.def_span(self.def_id())
+    }
+}
+
+impl<'tcx> Key for (ty::PolyTraitRef<'tcx>, ty::PolyTraitRef<'tcx>) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        tcx.def_span(self.0.def_id())
+    }
+}
+
+impl<'tcx> Key for GenericArg<'tcx> {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl<'tcx> Key for ty::Const<'tcx> {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl<'tcx> Key for Ty<'tcx> {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+
+    fn ty_adt_id(&self) -> Option<DefId> {
+        match self.kind() {
+            ty::Adt(adt, _) => Some(adt.did()),
+            _ => None,
+        }
+    }
+}
+
+impl<'tcx> Key for TyAndLayout<'tcx> {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl<'tcx> Key for (Ty<'tcx>, Ty<'tcx>) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl<'tcx> Key for &'tcx ty::List<ty::Clause<'tcx>> {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl<'tcx> Key for ty::ParamEnv<'tcx> {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl<'tcx, T: Key> Key for ty::ParamEnvAnd<'tcx, T> {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        self.value.default_span(tcx)
+    }
+}
+
+impl Key for Symbol {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl Key for Option<Symbol> {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+/// 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>;
+
+    fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl Key for (Symbol, u32, u32) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl<'tcx> Key for (DefId, Ty<'tcx>, GenericArgsRef<'tcx>, ty::ParamEnv<'tcx>) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl<'tcx> Key for (ty::Predicate<'tcx>, traits::WellFormedLoc) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _tcx: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl<'tcx> Key for (ty::PolyFnSig<'tcx>, &'tcx ty::List<Ty<'tcx>>) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl<'tcx> Key for (ty::Instance<'tcx>, &'tcx ty::List<Ty<'tcx>>) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        self.0.default_span(tcx)
+    }
+}
+
+impl<'tcx> Key for (Ty<'tcx>, ty::ValTree<'tcx>) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl Key for HirId {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        tcx.hir().span(*self)
+    }
+
+    #[inline(always)]
+    fn key_as_def_id(&self) -> Option<DefId> {
+        None
+    }
+}
+
+impl<'tcx> Key for (ValidityRequirement, ty::ParamEnvAnd<'tcx, Ty<'tcx>>) {
+    type CacheSelector = DefaultCacheSelector<Self>;
+
+    // Just forward to `Ty<'tcx>`
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+
+    fn ty_adt_id(&self) -> Option<DefId> {
+        match self.1.value.kind() {
+            ty::Adt(adt, _) => Some(adt.did()),
+            _ => None,
+        }
+    }
+}