compiler/rustc_middle/src/query/plumbing.rs - rust - Git at Google

 use std::fmt;
 use std::ops::Deref;

 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::hash_table::HashTable;
 use rustc_data_structures::sharded::Sharded;
 use rustc_data_structures::sync::{AtomicU64, WorkerLocal};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::hir_id::OwnerId;
 use rustc_macros::HashStable;
 use rustc_span::{ErrorGuaranteed, Span};
 pub use sealed::IntoQueryParam;

 use crate::dep_graph::{DepKind, DepNodeIndex, SerializedDepNodeIndex};
 use crate::ich::StableHashingContext;
 use crate::queries::{ExternProviders, Providers, QueryArenas, QueryVTables};
 use crate::query::on_disk_cache::OnDiskCache;
 use crate::query::stack::{QueryStackDeferred, QueryStackFrame, QueryStackFrameExtra};
 use crate::query::{QueryCache, QueryInfo, QueryJob};
 use crate::ty::TyCtxt;

 /// For a particular query, keeps track of "active" keys, i.e. keys whose
 /// evaluation has started but has not yet finished successfully.
 ///
 /// (Successful query evaluation for a key is represented by an entry in the
 /// query's in-memory cache.)
 pub struct QueryState<'tcx, K> {
     pub active: Sharded<HashTable<(K, ActiveKeyStatus<'tcx>)>>,
 }

 impl<'tcx, K> Default for QueryState<'tcx, K> {
     fn default() -> QueryState<'tcx, K> {
         QueryState { active: Default::default() }
     }
 }

 /// For a particular query and key, tracks the status of a query evaluation
 /// that has started, but has not yet finished successfully.
 ///
 /// (Successful query evaluation for a key is represented by an entry in the
 /// query's in-memory cache.)
 pub enum ActiveKeyStatus<'tcx> {
     /// Some thread is already evaluating the query for this key.
     ///
     /// The enclosed [`QueryJob`] can be used to wait for it to finish.
     Started(QueryJob<'tcx>),

     /// The query panicked. Queries trying to wait on this will raise a fatal error which will
     /// silently panic.
     Poisoned,
 }

 /// How a particular query deals with query cycle errors.
 ///
 /// Inspected by the code that actually handles cycle errors, to decide what
 /// approach to use.
 #[derive(Copy, Clone)]
 pub enum CycleErrorHandling {
     Error,
     DelayBug,
     Stash,
 }

 #[derive(Clone, Debug)]
 pub struct CycleError<I = QueryStackFrameExtra> {
     /// The query and related span that uses the cycle.
     pub usage: Option<(Span, QueryStackFrame<I>)>,
     pub cycle: Vec<QueryInfo<I>>,
 }

 impl<'tcx> CycleError<QueryStackDeferred<'tcx>> {
     pub fn lift(&self) -> CycleError<QueryStackFrameExtra> {
         CycleError {
             usage: self.usage.as_ref().map(|(span, frame)| (*span, frame.lift())),
             cycle: self.cycle.iter().map(|info| info.lift()).collect(),
         }
     }
 }

 #[derive(Debug)]
 pub enum QueryMode {
     /// This is a normal query call to `tcx.$query(..)` or `tcx.at(span).$query(..)`.
     Get,
     /// This is a call to `tcx.ensure_ok().$query(..)` or `tcx.ensure_done().$query(..)`.
     Ensure { ensure_mode: EnsureMode },
 }

 /// Distinguishes between `tcx.ensure_ok()` and `tcx.ensure_done()` in shared
 /// code paths that handle both modes.
 #[derive(Debug)]
 pub enum EnsureMode {
     /// Corresponds to [`TyCtxt::ensure_ok`].
     Ok,
     /// Corresponds to [`TyCtxt::ensure_done`].
     Done,
 }

 /// Stores data and metadata (e.g. function pointers) for a particular query.
 pub struct QueryVTable<'tcx, C: QueryCache> {
     pub name: &'static str,

     /// True if this query has the `anon` modifier.
     pub anon: bool,
     /// True if this query has the `eval_always` modifier.
     pub eval_always: bool,
     /// True if this query has the `depth_limit` modifier.
     pub depth_limit: bool,
     /// True if this query has the `feedable` modifier.
     pub feedable: bool,

     pub dep_kind: DepKind,
     /// How this query deals with query cycle errors.
     pub cycle_error_handling: CycleErrorHandling,
     pub state: QueryState<'tcx, C::Key>,
     pub cache: C,

     /// Function pointer that actually calls this query's provider.
     /// Also performs some associated secondary tasks; see the macro-defined
     /// implementation in `mod invoke_provider_fn` for more details.
     ///
     /// This should be the only code that calls the provider function.
     pub invoke_provider_fn: fn(tcx: TyCtxt<'tcx>, key: C::Key) -> C::Value,

     pub will_cache_on_disk_for_key_fn: fn(tcx: TyCtxt<'tcx>, key: C::Key) -> bool,

     pub try_load_from_disk_fn: fn(
         tcx: TyCtxt<'tcx>,
         key: C::Key,
         prev_index: SerializedDepNodeIndex,
         index: DepNodeIndex,
     ) -> Option<C::Value>,

     pub is_loadable_from_disk_fn:
         fn(tcx: TyCtxt<'tcx>, key: C::Key, index: SerializedDepNodeIndex) -> bool,

     /// Function pointer that hashes this query's result values.
     ///
     /// For `no_hash` queries, this function pointer is None.
     pub hash_value_fn: Option<fn(&mut StableHashingContext<'_>, &C::Value) -> Fingerprint>,

     pub value_from_cycle_error:
         fn(tcx: TyCtxt<'tcx>, cycle_error: CycleError, guar: ErrorGuaranteed) -> C::Value,
     pub format_value: fn(&C::Value) -> String,

     /// Formats a human-readable description of this query and its key, as
     /// specified by the `desc` query modifier.
     ///
     /// Used when reporting query cycle errors and similar problems.
     pub description_fn: fn(TyCtxt<'tcx>, C::Key) -> String,

     /// Function pointer that is called by the query methods on [`TyCtxt`] and
     /// friends[^1], after they have checked the in-memory cache and found no
     /// existing value for this key.
     ///
     /// Transitive responsibilities include trying to load a disk-cached value
     /// if possible (incremental only), invoking the query provider if necessary,
     /// and putting the obtained value into the in-memory cache.
     ///
     /// [^1]: [`TyCtxt`], [`TyCtxtAt`], [`TyCtxtEnsureOk`], [`TyCtxtEnsureDone`]
     pub execute_query_fn: fn(TyCtxt<'tcx>, Span, C::Key, QueryMode) -> Option<C::Value>,
 }

 impl<'tcx, C: QueryCache> fmt::Debug for QueryVTable<'tcx, C> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         // When debug-printing a query vtable (e.g. for ICE or tracing),
         // just print the query name to know what query we're dealing with.
         // The other fields and flags are probably just unhelpful noise.
         //
         // If there is need for a more detailed dump of all flags and fields,
         // consider writing a separate dump method and calling it explicitly.
         f.write_str(self.name)
     }
 }

 pub struct QuerySystem<'tcx> {
     pub arenas: WorkerLocal<QueryArenas<'tcx>>,
     pub query_vtables: QueryVTables<'tcx>,

     /// This provides access to the incremental compilation on-disk cache for query results.
     /// Do not access this directly. It is only meant to be used by
     /// `DepGraph::try_mark_green()` and the query infrastructure.
     /// This is `None` if we are not incremental compilation mode
     pub on_disk_cache: Option<OnDiskCache>,

     pub local_providers: Providers,
     pub extern_providers: ExternProviders,

     pub jobs: AtomicU64,
 }

 #[derive(Copy, Clone)]
 pub struct TyCtxtAt<'tcx> {
     pub tcx: TyCtxt<'tcx>,
     pub span: Span,
 }

 impl<'tcx> Deref for TyCtxtAt<'tcx> {
     type Target = TyCtxt<'tcx>;
     #[inline(always)]
     fn deref(&self) -> &Self::Target {
         &self.tcx
     }
 }

 #[derive(Copy, Clone)]
 #[must_use]
 pub struct TyCtxtEnsureOk<'tcx> {
     pub tcx: TyCtxt<'tcx>,
 }

 #[derive(Copy, Clone)]
 #[must_use]
 pub struct TyCtxtEnsureResult<'tcx> {
     pub tcx: TyCtxt<'tcx>,
 }

 #[derive(Copy, Clone)]
 #[must_use]
 pub struct TyCtxtEnsureDone<'tcx> {
     pub tcx: TyCtxt<'tcx>,
 }

 impl<'tcx> TyCtxt<'tcx> {
     /// FIXME: `ensure_ok`'s effects are subtle. Is this comment fully accurate?
     ///
     /// Wrapper that calls queries in a special "ensure OK" mode, for callers
     /// that don't need the return value and just want to invoke a query for
     /// its potential side-effect of emitting fatal errors.
     ///
     /// This can be more efficient than a normal query call, because if the
     /// query's inputs are all green, the call can return immediately without
     /// needing to obtain a value (by decoding one from disk or by executing
     /// the query).
     ///
     /// (As with all query calls, execution is also skipped if the query result
     /// is already cached in memory.)
     ///
     /// ## WARNING
     /// A subsequent normal call to the same query might still cause it to be
     /// executed! This can occur when the inputs are all green, but the query's
     /// result is not cached on disk, so the query must be executed to obtain a
     /// return value.
     ///
     /// Therefore, this call mode is not appropriate for callers that want to
     /// ensure that the query is _never_ executed in the future.
     #[inline(always)]
     pub fn ensure_ok(self) -> TyCtxtEnsureOk<'tcx> {
         TyCtxtEnsureOk { tcx: self }
     }

     /// This is a variant of `ensure_ok` only usable with queries that return
     /// `Result<_, ErrorGuaranteed>`. Queries calls through this function will
     /// return `Result<(), ErrorGuaranteed>`. I.e. the error status is returned
     /// but nothing else. As with `ensure_ok`, this can be more efficient than
     /// a normal query call.
     #[inline(always)]
     pub fn ensure_result(self) -> TyCtxtEnsureResult<'tcx> {
         TyCtxtEnsureResult { tcx: self }
     }

     /// Wrapper that calls queries in a special "ensure done" mode, for callers
     /// that don't need the return value and just want to guarantee that the
     /// query won't be executed in the future, by executing it now if necessary.
     ///
     /// This is useful for queries that read from a [`Steal`] value, to ensure
     /// that they are executed before the query that will steal the value.
     ///
     /// Unlike [`Self::ensure_ok`], a query with all-green inputs will only be
     /// skipped if its return value is stored in the disk-cache. This is still
     /// more efficient than a regular query, because in that situation the
     /// return value doesn't necessarily need to be decoded.
     ///
     /// (As with all query calls, execution is also skipped if the query result
     /// is already cached in memory.)
     ///
     /// [`Steal`]: rustc_data_structures::steal::Steal
     #[inline(always)]
     pub fn ensure_done(self) -> TyCtxtEnsureDone<'tcx> {
         TyCtxtEnsureDone { tcx: self }
     }

     /// Returns a transparent wrapper for `TyCtxt` which uses
     /// `span` as the location of queries performed through it.
     #[inline(always)]
     pub fn at(self, span: Span) -> TyCtxtAt<'tcx> {
         TyCtxtAt { tcx: self, span }
     }
 }

 macro_rules! query_helper_param_ty {
     (DefId) => { impl $crate::query::IntoQueryParam<DefId> };
     (LocalDefId) => { impl $crate::query::IntoQueryParam<LocalDefId> };
     ($K:ty) => { $K };
 }

 macro_rules! define_callbacks {
     (
         // You might expect the key to be `$K:ty`, but it needs to be `$($K:tt)*` so that
         // `query_helper_param_ty!` can match on specific type names.
         queries {
             $(
                 $(#[$attr:meta])*
                 fn $name:ident($($K:tt)*) -> $V:ty
                 {
                     // Search for (QMODLIST) to find all occurrences of this query modifier list.
                     anon: $anon:literal,
                     arena_cache: $arena_cache:literal,
                     cache_on_disk: $cache_on_disk:literal,
                     cycle_error_handling: $cycle_error_handling:ident,
                     depth_limit: $depth_limit:literal,
                     eval_always: $eval_always:literal,
                     feedable: $feedable:literal,
                     no_hash: $no_hash:literal,
                     returns_error_guaranteed: $returns_error_guaranteed:literal,
                     separate_provide_extern: $separate_provide_extern:literal,
                 }
             )*
         }
         // Non-queries are unused here.
         non_queries { $($_:tt)* }
     ) => {
         $(
             #[allow(unused_lifetimes)]
             pub mod $name {
                 use super::*;
                 use $crate::query::erase::{self, Erased};

                 pub type Key<'tcx> = $($K)*;
                 pub type Value<'tcx> = $V;

                 /// Key type used by provider functions in `local_providers`.
                 /// This query has the `separate_provide_extern` modifier.
                 #[cfg($separate_provide_extern)]
                 pub type LocalKey<'tcx> =
                     <Key<'tcx> as $crate::query::AsLocalQueryKey>::LocalQueryKey;
                 /// Key type used by provider functions in `local_providers`.
                 #[cfg(not($separate_provide_extern))]
                 pub type LocalKey<'tcx> = Key<'tcx>;

                 /// Type returned from query providers and loaded from disk-cache.
                 #[cfg($arena_cache)]
                 pub type ProvidedValue<'tcx> =
                     <Value<'tcx> as $crate::query::arena_cached::ArenaCached<'tcx>>::Provided;
                 /// Type returned from query providers and loaded from disk-cache.
                 #[cfg(not($arena_cache))]
                 pub type ProvidedValue<'tcx> = Value<'tcx>;

                 /// This helper function takes a value returned by the query provider
                 /// (or loaded from disk, or supplied by query feeding), allocates
                 /// it in an arena if requested by the `arena_cache` modifier, and
                 /// then returns an erased copy of it.
                 #[inline(always)]
                 pub fn provided_to_erased<'tcx>(
                     tcx: TyCtxt<'tcx>,
                     provided_value: ProvidedValue<'tcx>,
                 ) -> Erased<Value<'tcx>> {
                     // For queries with the `arena_cache` modifier, store the
                     // provided value in an arena and get a reference to it.
                     #[cfg($arena_cache)]
                     let value: Value<'tcx> = {
                         use $crate::query::arena_cached::ArenaCached;
                         <Value<'tcx> as ArenaCached>::alloc_in_arena(
                             tcx,
                             &tcx.query_system.arenas.$name,
                             provided_value,
                         )
                     };

                     // Otherwise, the provided value is the value (and `tcx` is unused).
                     #[cfg(not($arena_cache))]
                     let value: Value<'tcx> = {
                         let _ = tcx;
                         provided_value
                     };

                     erase::erase_val(value)
                 }

                 pub type Cache<'tcx> =
                     <Key<'tcx> as $crate::query::QueryKey>::Cache<Erased<Value<'tcx>>>;

                 // Ensure that keys grow no larger than 88 bytes by accident.
                 // Increase this limit if necessary, but do try to keep the size low if possible
                 #[cfg(target_pointer_width = "64")]
                 const _: () = {
                     if size_of::<Key<'static>>() > 88 {
                         panic!("{}", concat!(
                             "the query `",
                             stringify!($name),
                             "` has a key type `",
                             stringify!($($K)*),
                             "` that is too large"
                         ));
                     }
                 };

                 // Ensure that values grow no larger than 64 bytes by accident.
                 // Increase this limit if necessary, but do try to keep the size low if possible
                 #[cfg(target_pointer_width = "64")]
                 #[cfg(not(feature = "rustc_randomized_layouts"))]
                 const _: () = {
                     if size_of::<Value<'static>>() > 64 {
                         panic!("{}", concat!(
                             "the query `",
                             stringify!($name),
                             "` has a value type `",
                             stringify!($V),
                             "` that is too large"
                         ));
                     }
                 };
             }
         )*

         /// Holds per-query arenas for queries with the `arena_cache` modifier.
         #[derive(Default)]
         pub struct QueryArenas<'tcx> {
             $(
                 // Use the `ArenaCached` helper trait to determine the arena's value type.
                 #[cfg($arena_cache)]
                 pub $name: TypedArena<
                     <$V as $crate::query::arena_cached::ArenaCached<'tcx>>::Allocated,
                 >,
             )*
         }

         impl<'tcx> $crate::query::TyCtxtEnsureOk<'tcx> {
             $(
                 $(#[$attr])*
                 #[inline(always)]
                 pub fn $name(self, key: query_helper_param_ty!($($K)*)) {
                     crate::query::inner::query_ensure_ok_or_done(
                         self.tcx,
                         &self.tcx.query_system.query_vtables.$name,
                         $crate::query::IntoQueryParam::into_query_param(key),
                         $crate::query::EnsureMode::Ok,
                     )
                 }
             )*
         }

         // Only defined when the `ensure_result` modifier is present.
         impl<'tcx> $crate::query::TyCtxtEnsureResult<'tcx> {
             $(
                 #[cfg($returns_error_guaranteed)]
                 $(#[$attr])*
                 #[inline(always)]
                 pub fn $name(
                     self,
                     key: query_helper_param_ty!($($K)*),
                 ) -> Result<(), rustc_errors::ErrorGuaranteed> {
                     crate::query::inner::query_ensure_result(
                         self.tcx,
                         &self.tcx.query_system.query_vtables.$name,
                         $crate::query::IntoQueryParam::into_query_param(key),
                     )
                 }
             )*
         }

         impl<'tcx> $crate::query::TyCtxtEnsureDone<'tcx> {
             $(
                 $(#[$attr])*
                 #[inline(always)]
                 pub fn $name(self, key: query_helper_param_ty!($($K)*)) {
                     crate::query::inner::query_ensure_ok_or_done(
                         self.tcx,
                         &self.tcx.query_system.query_vtables.$name,
                         $crate::query::IntoQueryParam::into_query_param(key),
                         $crate::query::EnsureMode::Done,
                     );
                 }
             )*
         }

         impl<'tcx> TyCtxt<'tcx> {
             $(
                 $(#[$attr])*
                 #[inline(always)]
                 #[must_use]
                 pub fn $name(self, key: query_helper_param_ty!($($K)*)) -> $V {
                     self.at(DUMMY_SP).$name(key)
                 }
             )*
         }

         impl<'tcx> $crate::query::TyCtxtAt<'tcx> {
             $(
                 $(#[$attr])*
                 #[inline(always)]
                 pub fn $name(self, key: query_helper_param_ty!($($K)*)) -> $V {
                     use $crate::query::{erase, inner};

                     erase::restore_val::<$V>(inner::query_get_at(
                         self.tcx,
                         self.span,
                         &self.tcx.query_system.query_vtables.$name,
                         $crate::query::IntoQueryParam::into_query_param(key),
                     ))
                 }
             )*
         }

         $(
             #[cfg($feedable)]
             impl<'tcx, K: $crate::query::IntoQueryParam<$name::Key<'tcx>> + Copy>
                 TyCtxtFeed<'tcx, K>
             {
                 $(#[$attr])*
                 #[inline(always)]
                 pub fn $name(self, value: $name::ProvidedValue<'tcx>) {
                     let key = self.key().into_query_param();
                     let erased_value = $name::provided_to_erased(self.tcx, value);
                     $crate::query::inner::query_feed(
                         self.tcx,
                         dep_graph::DepKind::$name,
                         &self.tcx.query_system.query_vtables.$name,
                         key,
                         erased_value,
                     );
                 }
             }
         )*

         /// Holds a `QueryVTable` for each query.
         pub struct QueryVTables<'tcx> {
             $(
                 pub $name: ::rustc_middle::query::plumbing::QueryVTable<'tcx, $name::Cache<'tcx>>,
             )*
         }

         pub struct Providers {
             $(
                 /// This is the provider for the query. Use `Find references` on this to
                 /// navigate between the provider assignment and the query definition.
                 pub $name: for<'tcx> fn(
                     TyCtxt<'tcx>,
                     $name::LocalKey<'tcx>,
                 ) -> $name::ProvidedValue<'tcx>,
             )*
         }

         pub struct ExternProviders {
             $(
                 #[cfg($separate_provide_extern)]
                 pub $name: for<'tcx> fn(
                     TyCtxt<'tcx>,
                     $name::Key<'tcx>,
                 ) -> $name::ProvidedValue<'tcx>,
             )*
         }

         impl Default for Providers {
             fn default() -> Self {
                 Providers {
                     $(
                         $name: |_, key| {
                             $crate::query::plumbing::default_query(stringify!($name), &key)
                         },
                     )*
                 }
             }
         }

         impl Default for ExternProviders {
             fn default() -> Self {
                 ExternProviders {
                     $(
                         #[cfg($separate_provide_extern)]
                         $name: |_, key| $crate::query::plumbing::default_extern_query(
                             stringify!($name),
                             &key,
                         ),
                     )*
                 }
             }
         }

         impl Copy for Providers {}
         impl Clone for Providers {
             fn clone(&self) -> Self { *self }
         }

         impl Copy for ExternProviders {}
         impl Clone for ExternProviders {
             fn clone(&self) -> Self { *self }
         }
     };
 }

 mod sealed {
     use rustc_hir::def_id::{LocalModDefId, ModDefId};

     use super::{DefId, LocalDefId, OwnerId};

     /// An analogue of the `Into` trait that's intended only for query parameters.
     ///
     /// This exists to allow queries to accept either `DefId` or `LocalDefId` while requiring that the
     /// user call `to_def_id` to convert between them everywhere else.
     pub trait IntoQueryParam<P> {
         fn into_query_param(self) -> P;
     }

     impl<P> IntoQueryParam<P> for P {
         #[inline(always)]
         fn into_query_param(self) -> P {
             self
         }
     }

     impl IntoQueryParam<LocalDefId> for OwnerId {
         #[inline(always)]
         fn into_query_param(self) -> LocalDefId {
             self.def_id
         }
     }

     impl IntoQueryParam<DefId> for LocalDefId {
         #[inline(always)]
         fn into_query_param(self) -> DefId {
             self.to_def_id()
         }
     }

     impl IntoQueryParam<DefId> for OwnerId {
         #[inline(always)]
         fn into_query_param(self) -> DefId {
             self.to_def_id()
         }
     }

     impl IntoQueryParam<DefId> for ModDefId {
         #[inline(always)]
         fn into_query_param(self) -> DefId {
             self.to_def_id()
         }
     }

     impl IntoQueryParam<DefId> for LocalModDefId {
         #[inline(always)]
         fn into_query_param(self) -> DefId {
             self.to_def_id()
         }
     }

     impl IntoQueryParam<LocalDefId> for LocalModDefId {
         #[inline(always)]
         fn into_query_param(self) -> LocalDefId {
             self.into()
         }
     }
 }

 #[derive(Copy, Clone, Debug, HashStable)]
 pub struct CyclePlaceholder(pub ErrorGuaranteed);

 #[cold]
 pub(crate) fn default_query(name: &str, key: &dyn std::fmt::Debug) -> ! {
     bug!(
         "`tcx.{name}({key:?})` is not supported for this key;\n\
         hint: Queries can be either made to the local crate, or the external crate. \
         This error means you tried to use it for one that's not supported.\n\
         If that's not the case, {name} was likely never assigned to a provider function.\n",
     )
 }

 #[cold]
 pub(crate) fn default_extern_query(name: &str, key: &dyn std::fmt::Debug) -> ! {
     bug!(
         "`tcx.{name}({key:?})` unsupported by its crate; \
          perhaps the `{name}` query was never assigned a provider function",
     )
 }
	use std::fmt;
	use std::ops::Deref;

	use rustc_data_structures::fingerprint::Fingerprint;
	use rustc_data_structures::hash_table::HashTable;
	use rustc_data_structures::sharded::Sharded;
	use rustc_data_structures::sync::{AtomicU64, WorkerLocal};
	use rustc_hir::def_id::{DefId, LocalDefId};
	use rustc_hir::hir_id::OwnerId;
	use rustc_macros::HashStable;
	use rustc_span::{ErrorGuaranteed, Span};
	pub use sealed::IntoQueryParam;

	use crate::dep_graph::{DepKind, DepNodeIndex, SerializedDepNodeIndex};
	use crate::ich::StableHashingContext;
	use crate::queries::{ExternProviders, Providers, QueryArenas, QueryVTables};
	use crate::query::on_disk_cache::OnDiskCache;
	use crate::query::stack::{QueryStackDeferred, QueryStackFrame, QueryStackFrameExtra};
	use crate::query::{QueryCache, QueryInfo, QueryJob};
	use crate::ty::TyCtxt;

	/// For a particular query, keeps track of "active" keys, i.e. keys whose
	/// evaluation has started but has not yet finished successfully.
	///
	/// (Successful query evaluation for a key is represented by an entry in the
	/// query's in-memory cache.)
	pub struct QueryState<'tcx, K> {
	pub active: Sharded<HashTable<(K, ActiveKeyStatus<'tcx>)>>,
	}

	impl<'tcx, K> Default for QueryState<'tcx, K> {
	fn default() -> QueryState<'tcx, K> {
	QueryState { active: Default::default() }
	}
	}

	/// For a particular query and key, tracks the status of a query evaluation
	/// that has started, but has not yet finished successfully.
	///
	/// (Successful query evaluation for a key is represented by an entry in the
	/// query's in-memory cache.)
	pub enum ActiveKeyStatus<'tcx> {
	/// Some thread is already evaluating the query for this key.
	///
	/// The enclosed [`QueryJob`] can be used to wait for it to finish.
	Started(QueryJob<'tcx>),

	/// The query panicked. Queries trying to wait on this will raise a fatal error which will
	/// silently panic.
	Poisoned,
	}

	/// How a particular query deals with query cycle errors.
	///
	/// Inspected by the code that actually handles cycle errors, to decide what
	/// approach to use.
	#[derive(Copy, Clone)]
	pub enum CycleErrorHandling {
	Error,
	DelayBug,
	Stash,
	}

	#[derive(Clone, Debug)]
	pub struct CycleError<I = QueryStackFrameExtra> {
	/// The query and related span that uses the cycle.
	pub usage: Option<(Span, QueryStackFrame<I>)>,
	pub cycle: Vec<QueryInfo<I>>,
	}

	impl<'tcx> CycleError<QueryStackDeferred<'tcx>> {
	pub fn lift(&self) -> CycleError<QueryStackFrameExtra> {
	CycleError {
	usage: self.usage.as_ref().map(\|(span, frame)\| (*span, frame.lift())),
	cycle: self.cycle.iter().map(\|info\| info.lift()).collect(),
	}
	}
	}

	#[derive(Debug)]
	pub enum QueryMode {
	/// This is a normal query call to `tcx.$query(..)` or `tcx.at(span).$query(..)`.
	Get,
	/// This is a call to `tcx.ensure_ok().$query(..)` or `tcx.ensure_done().$query(..)`.
	Ensure { ensure_mode: EnsureMode },
	}

	/// Distinguishes between `tcx.ensure_ok()` and `tcx.ensure_done()` in shared
	/// code paths that handle both modes.
	#[derive(Debug)]
	pub enum EnsureMode {
	/// Corresponds to [`TyCtxt::ensure_ok`].
	Ok,
	/// Corresponds to [`TyCtxt::ensure_done`].
	Done,
	}

	/// Stores data and metadata (e.g. function pointers) for a particular query.
	pub struct QueryVTable<'tcx, C: QueryCache> {
	pub name: &'static str,

	/// True if this query has the `anon` modifier.
	pub anon: bool,
	/// True if this query has the `eval_always` modifier.
	pub eval_always: bool,
	/// True if this query has the `depth_limit` modifier.
	pub depth_limit: bool,
	/// True if this query has the `feedable` modifier.
	pub feedable: bool,

	pub dep_kind: DepKind,
	/// How this query deals with query cycle errors.
	pub cycle_error_handling: CycleErrorHandling,
	pub state: QueryState<'tcx, C::Key>,
	pub cache: C,

	/// Function pointer that actually calls this query's provider.
	/// Also performs some associated secondary tasks; see the macro-defined
	/// implementation in `mod invoke_provider_fn` for more details.
	///
	/// This should be the only code that calls the provider function.
	pub invoke_provider_fn: fn(tcx: TyCtxt<'tcx>, key: C::Key) -> C::Value,

	pub will_cache_on_disk_for_key_fn: fn(tcx: TyCtxt<'tcx>, key: C::Key) -> bool,

	pub try_load_from_disk_fn: fn(
	tcx: TyCtxt<'tcx>,
	key: C::Key,
	prev_index: SerializedDepNodeIndex,
	index: DepNodeIndex,
	) -> Option<C::Value>,

	pub is_loadable_from_disk_fn:
	fn(tcx: TyCtxt<'tcx>, key: C::Key, index: SerializedDepNodeIndex) -> bool,

	/// Function pointer that hashes this query's result values.
	///
	/// For `no_hash` queries, this function pointer is None.
	pub hash_value_fn: Option<fn(&mut StableHashingContext<'_>, &C::Value) -> Fingerprint>,

	pub value_from_cycle_error:
	fn(tcx: TyCtxt<'tcx>, cycle_error: CycleError, guar: ErrorGuaranteed) -> C::Value,
	pub format_value: fn(&C::Value) -> String,

	/// Formats a human-readable description of this query and its key, as
	/// specified by the `desc` query modifier.
	///
	/// Used when reporting query cycle errors and similar problems.
	pub description_fn: fn(TyCtxt<'tcx>, C::Key) -> String,

	/// Function pointer that is called by the query methods on [`TyCtxt`] and
	/// friends[^1], after they have checked the in-memory cache and found no
	/// existing value for this key.
	///
	/// Transitive responsibilities include trying to load a disk-cached value
	/// if possible (incremental only), invoking the query provider if necessary,
	/// and putting the obtained value into the in-memory cache.
	///
	/// [^1]: [`TyCtxt`], [`TyCtxtAt`], [`TyCtxtEnsureOk`], [`TyCtxtEnsureDone`]
	pub execute_query_fn: fn(TyCtxt<'tcx>, Span, C::Key, QueryMode) -> Option<C::Value>,
	}

	impl<'tcx, C: QueryCache> fmt::Debug for QueryVTable<'tcx, C> {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
	// When debug-printing a query vtable (e.g. for ICE or tracing),
	// just print the query name to know what query we're dealing with.
	// The other fields and flags are probably just unhelpful noise.
	//
	// If there is need for a more detailed dump of all flags and fields,
	// consider writing a separate dump method and calling it explicitly.
	f.write_str(self.name)
	}
	}

	pub struct QuerySystem<'tcx> {
	pub arenas: WorkerLocal<QueryArenas<'tcx>>,
	pub query_vtables: QueryVTables<'tcx>,

	/// This provides access to the incremental compilation on-disk cache for query results.
	/// Do not access this directly. It is only meant to be used by
	/// `DepGraph::try_mark_green()` and the query infrastructure.
	/// This is `None` if we are not incremental compilation mode
	pub on_disk_cache: Option<OnDiskCache>,

	pub local_providers: Providers,
	pub extern_providers: ExternProviders,

	pub jobs: AtomicU64,
	}

	#[derive(Copy, Clone)]
	pub struct TyCtxtAt<'tcx> {
	pub tcx: TyCtxt<'tcx>,
	pub span: Span,
	}

	impl<'tcx> Deref for TyCtxtAt<'tcx> {
	type Target = TyCtxt<'tcx>;
	#[inline(always)]
	fn deref(&self) -> &Self::Target {
	&self.tcx
	}
	}

	#[derive(Copy, Clone)]
	#[must_use]
	pub struct TyCtxtEnsureOk<'tcx> {
	pub tcx: TyCtxt<'tcx>,
	}

	#[derive(Copy, Clone)]
	#[must_use]
	pub struct TyCtxtEnsureResult<'tcx> {
	pub tcx: TyCtxt<'tcx>,
	}

	#[derive(Copy, Clone)]
	#[must_use]
	pub struct TyCtxtEnsureDone<'tcx> {
	pub tcx: TyCtxt<'tcx>,
	}

	impl<'tcx> TyCtxt<'tcx> {
	/// FIXME: `ensure_ok`'s effects are subtle. Is this comment fully accurate?
	///
	/// Wrapper that calls queries in a special "ensure OK" mode, for callers
	/// that don't need the return value and just want to invoke a query for
	/// its potential side-effect of emitting fatal errors.
	///
	/// This can be more efficient than a normal query call, because if the
	/// query's inputs are all green, the call can return immediately without
	/// needing to obtain a value (by decoding one from disk or by executing
	/// the query).
	///
	/// (As with all query calls, execution is also skipped if the query result
	/// is already cached in memory.)
	///
	/// ## WARNING
	/// A subsequent normal call to the same query might still cause it to be
	/// executed! This can occur when the inputs are all green, but the query's
	/// result is not cached on disk, so the query must be executed to obtain a
	/// return value.
	///
	/// Therefore, this call mode is not appropriate for callers that want to
	/// ensure that the query is _never_ executed in the future.
	#[inline(always)]
	pub fn ensure_ok(self) -> TyCtxtEnsureOk<'tcx> {
	TyCtxtEnsureOk { tcx: self }
	}

	/// This is a variant of `ensure_ok` only usable with queries that return
	/// `Result<_, ErrorGuaranteed>`. Queries calls through this function will
	/// return `Result<(), ErrorGuaranteed>`. I.e. the error status is returned
	/// but nothing else. As with `ensure_ok`, this can be more efficient than
	/// a normal query call.
	#[inline(always)]
	pub fn ensure_result(self) -> TyCtxtEnsureResult<'tcx> {
	TyCtxtEnsureResult { tcx: self }
	}

	/// Wrapper that calls queries in a special "ensure done" mode, for callers
	/// that don't need the return value and just want to guarantee that the
	/// query won't be executed in the future, by executing it now if necessary.
	///
	/// This is useful for queries that read from a [`Steal`] value, to ensure
	/// that they are executed before the query that will steal the value.
	///
	/// Unlike [`Self::ensure_ok`], a query with all-green inputs will only be
	/// skipped if its return value is stored in the disk-cache. This is still
	/// more efficient than a regular query, because in that situation the
	/// return value doesn't necessarily need to be decoded.
	///
	/// (As with all query calls, execution is also skipped if the query result
	/// is already cached in memory.)
	///
	/// [`Steal`]: rustc_data_structures::steal::Steal
	#[inline(always)]
	pub fn ensure_done(self) -> TyCtxtEnsureDone<'tcx> {
	TyCtxtEnsureDone { tcx: self }
	}

	/// Returns a transparent wrapper for `TyCtxt` which uses
	/// `span` as the location of queries performed through it.
	#[inline(always)]
	pub fn at(self, span: Span) -> TyCtxtAt<'tcx> {
	TyCtxtAt { tcx: self, span }
	}
	}

	macro_rules! query_helper_param_ty {
	(DefId) => { impl $crate::query::IntoQueryParam<DefId> };
	(LocalDefId) => { impl $crate::query::IntoQueryParam<LocalDefId> };
	($K:ty) => { $K };
	}

	macro_rules! define_callbacks {
	(
	// You might expect the key to be `$K:ty`, but it needs to be `$($K:tt)*` so that
	// `query_helper_param_ty!` can match on specific type names.
	queries {
	$(
	$(#[$attr:meta])*
	fn $name:ident($($K:tt)*) -> $V:ty
	{
	// Search for (QMODLIST) to find all occurrences of this query modifier list.
	anon: $anon:literal,
	arena_cache: $arena_cache:literal,
	cache_on_disk: $cache_on_disk:literal,
	cycle_error_handling: $cycle_error_handling:ident,
	depth_limit: $depth_limit:literal,
	eval_always: $eval_always:literal,
	feedable: $feedable:literal,
	no_hash: $no_hash:literal,
	returns_error_guaranteed: $returns_error_guaranteed:literal,
	separate_provide_extern: $separate_provide_extern:literal,
	}
	)*
	}
	// Non-queries are unused here.
	non_queries { $($_:tt)* }
	) => {
	$(
	#[allow(unused_lifetimes)]
	pub mod $name {
	use super::*;
	use $crate::query::erase::{self, Erased};

	pub type Key<'tcx> = $($K)*;
	pub type Value<'tcx> = $V;

	/// Key type used by provider functions in `local_providers`.
	/// This query has the `separate_provide_extern` modifier.
	#[cfg($separate_provide_extern)]
	pub type LocalKey<'tcx> =
	<Key<'tcx> as $crate::query::AsLocalQueryKey>::LocalQueryKey;
	/// Key type used by provider functions in `local_providers`.
	#[cfg(not($separate_provide_extern))]
	pub type LocalKey<'tcx> = Key<'tcx>;

	/// Type returned from query providers and loaded from disk-cache.
	#[cfg($arena_cache)]
	pub type ProvidedValue<'tcx> =
	<Value<'tcx> as $crate::query::arena_cached::ArenaCached<'tcx>>::Provided;
	/// Type returned from query providers and loaded from disk-cache.
	#[cfg(not($arena_cache))]
	pub type ProvidedValue<'tcx> = Value<'tcx>;

	/// This helper function takes a value returned by the query provider
	/// (or loaded from disk, or supplied by query feeding), allocates
	/// it in an arena if requested by the `arena_cache` modifier, and
	/// then returns an erased copy of it.
	#[inline(always)]
	pub fn provided_to_erased<'tcx>(
	tcx: TyCtxt<'tcx>,
	provided_value: ProvidedValue<'tcx>,
	) -> Erased<Value<'tcx>> {
	// For queries with the `arena_cache` modifier, store the
	// provided value in an arena and get a reference to it.
	#[cfg($arena_cache)]
	let value: Value<'tcx> = {
	use $crate::query::arena_cached::ArenaCached;
	<Value<'tcx> as ArenaCached>::alloc_in_arena(
	tcx,
	&tcx.query_system.arenas.$name,
	provided_value,
	)
	};

	// Otherwise, the provided value is the value (and `tcx` is unused).
	#[cfg(not($arena_cache))]
	let value: Value<'tcx> = {
	let _ = tcx;
	provided_value
	};

	erase::erase_val(value)
	}

	pub type Cache<'tcx> =
	<Key<'tcx> as $crate::query::QueryKey>::Cache<Erased<Value<'tcx>>>;

	// Ensure that keys grow no larger than 88 bytes by accident.
	// Increase this limit if necessary, but do try to keep the size low if possible
	#[cfg(target_pointer_width = "64")]
	const _: () = {
	if size_of::<Key<'static>>() > 88 {
	panic!("{}", concat!(
	"the query `",
	stringify!($name),
	"` has a key type `",
	stringify!($($K)*),
	"` that is too large"
	));
	}
	};

	// Ensure that values grow no larger than 64 bytes by accident.
	// Increase this limit if necessary, but do try to keep the size low if possible
	#[cfg(target_pointer_width = "64")]
	#[cfg(not(feature = "rustc_randomized_layouts"))]
	const _: () = {
	if size_of::<Value<'static>>() > 64 {
	panic!("{}", concat!(
	"the query `",
	stringify!($name),
	"` has a value type `",
	stringify!($V),
	"` that is too large"
	));
	}
	};
	}
	)*

	/// Holds per-query arenas for queries with the `arena_cache` modifier.
	#[derive(Default)]
	pub struct QueryArenas<'tcx> {
	$(
	// Use the `ArenaCached` helper trait to determine the arena's value type.
	#[cfg($arena_cache)]
	pub $name: TypedArena<
	<$V as $crate::query::arena_cached::ArenaCached<'tcx>>::Allocated,
	>,
	)*
	}

	impl<'tcx> $crate::query::TyCtxtEnsureOk<'tcx> {
	$(
	$(#[$attr])*
	#[inline(always)]
	pub fn $name(self, key: query_helper_param_ty!($($K)*)) {
	crate::query::inner::query_ensure_ok_or_done(
	self.tcx,
	&self.tcx.query_system.query_vtables.$name,
	$crate::query::IntoQueryParam::into_query_param(key),
	$crate::query::EnsureMode::Ok,
	)
	}
	)*
	}

	// Only defined when the `ensure_result` modifier is present.
	impl<'tcx> $crate::query::TyCtxtEnsureResult<'tcx> {
	$(
	#[cfg($returns_error_guaranteed)]
	$(#[$attr])*
	#[inline(always)]
	pub fn $name(
	self,
	key: query_helper_param_ty!($($K)*),
	) -> Result<(), rustc_errors::ErrorGuaranteed> {
	crate::query::inner::query_ensure_result(
	self.tcx,
	&self.tcx.query_system.query_vtables.$name,
	$crate::query::IntoQueryParam::into_query_param(key),
	)
	}
	)*
	}

	impl<'tcx> $crate::query::TyCtxtEnsureDone<'tcx> {
	$(
	$(#[$attr])*
	#[inline(always)]
	pub fn $name(self, key: query_helper_param_ty!($($K)*)) {
	crate::query::inner::query_ensure_ok_or_done(
	self.tcx,
	&self.tcx.query_system.query_vtables.$name,
	$crate::query::IntoQueryParam::into_query_param(key),
	$crate::query::EnsureMode::Done,
	);
	}
	)*
	}

	impl<'tcx> TyCtxt<'tcx> {
	$(
	$(#[$attr])*
	#[inline(always)]
	#[must_use]
	pub fn $name(self, key: query_helper_param_ty!($($K)*)) -> $V {
	self.at(DUMMY_SP).$name(key)
	}
	)*
	}

	impl<'tcx> $crate::query::TyCtxtAt<'tcx> {
	$(
	$(#[$attr])*
	#[inline(always)]
	pub fn $name(self, key: query_helper_param_ty!($($K)*)) -> $V {
	use $crate::query::{erase, inner};

	erase::restore_val::<$V>(inner::query_get_at(
	self.tcx,
	self.span,
	&self.tcx.query_system.query_vtables.$name,
	$crate::query::IntoQueryParam::into_query_param(key),
	))
	}
	)*
	}

	$(
	#[cfg($feedable)]
	impl<'tcx, K: $crate::query::IntoQueryParam<$name::Key<'tcx>> + Copy>
	TyCtxtFeed<'tcx, K>
	{
	$(#[$attr])*
	#[inline(always)]
	pub fn $name(self, value: $name::ProvidedValue<'tcx>) {
	let key = self.key().into_query_param();
	let erased_value = $name::provided_to_erased(self.tcx, value);
	$crate::query::inner::query_feed(
	self.tcx,
	dep_graph::DepKind::$name,
	&self.tcx.query_system.query_vtables.$name,
	key,
	erased_value,
	);
	}
	}
	)*

	/// Holds a `QueryVTable` for each query.
	pub struct QueryVTables<'tcx> {
	$(
	pub $name: ::rustc_middle::query::plumbing::QueryVTable<'tcx, $name::Cache<'tcx>>,
	)*
	}

	pub struct Providers {
	$(
	/// This is the provider for the query. Use `Find references` on this to
	/// navigate between the provider assignment and the query definition.
	pub $name: for<'tcx> fn(
	TyCtxt<'tcx>,
	$name::LocalKey<'tcx>,
	) -> $name::ProvidedValue<'tcx>,
	)*
	}

	pub struct ExternProviders {
	$(
	#[cfg($separate_provide_extern)]
	pub $name: for<'tcx> fn(
	TyCtxt<'tcx>,
	$name::Key<'tcx>,
	) -> $name::ProvidedValue<'tcx>,
	)*
	}

	impl Default for Providers {
	fn default() -> Self {
	Providers {
	$(
	$name: \|_, key\| {
	$crate::query::plumbing::default_query(stringify!($name), &key)
	},
	)*
	}
	}
	}

	impl Default for ExternProviders {
	fn default() -> Self {
	ExternProviders {
	$(
	#[cfg($separate_provide_extern)]
	$name: \|_, key\| $crate::query::plumbing::default_extern_query(
	stringify!($name),
	&key,
	),
	)*
	}
	}
	}

	impl Copy for Providers {}
	impl Clone for Providers {
	fn clone(&self) -> Self { *self }
	}

	impl Copy for ExternProviders {}
	impl Clone for ExternProviders {
	fn clone(&self) -> Self { *self }
	}
	};
	}

	mod sealed {
	use rustc_hir::def_id::{LocalModDefId, ModDefId};

	use super::{DefId, LocalDefId, OwnerId};

	/// An analogue of the `Into` trait that's intended only for query parameters.
	///
	/// This exists to allow queries to accept either `DefId` or `LocalDefId` while requiring that the
	/// user call `to_def_id` to convert between them everywhere else.
	pub trait IntoQueryParam<P> {
	fn into_query_param(self) -> P;
	}

	impl<P> IntoQueryParam<P> for P {
	#[inline(always)]
	fn into_query_param(self) -> P {
	self
	}
	}

	impl IntoQueryParam<LocalDefId> for OwnerId {
	#[inline(always)]
	fn into_query_param(self) -> LocalDefId {
	self.def_id
	}
	}

	impl IntoQueryParam<DefId> for LocalDefId {
	#[inline(always)]
	fn into_query_param(self) -> DefId {
	self.to_def_id()
	}
	}

	impl IntoQueryParam<DefId> for OwnerId {
	#[inline(always)]
	fn into_query_param(self) -> DefId {
	self.to_def_id()
	}
	}

	impl IntoQueryParam<DefId> for ModDefId {
	#[inline(always)]
	fn into_query_param(self) -> DefId {
	self.to_def_id()
	}
	}

	impl IntoQueryParam<DefId> for LocalModDefId {
	#[inline(always)]
	fn into_query_param(self) -> DefId {
	self.to_def_id()
	}
	}

	impl IntoQueryParam<LocalDefId> for LocalModDefId {
	#[inline(always)]
	fn into_query_param(self) -> LocalDefId {
	self.into()
	}
	}
	}

	#[derive(Copy, Clone, Debug, HashStable)]
	pub struct CyclePlaceholder(pub ErrorGuaranteed);

	#[cold]
	pub(crate) fn default_query(name: &str, key: &dyn std::fmt::Debug) -> ! {
	bug!(
	"`tcx.{name}({key:?})` is not supported for this key;\n\
	hint: Queries can be either made to the local crate, or the external crate. \
	This error means you tried to use it for one that's not supported.\n\
	If that's not the case, {name} was likely never assigned to a provider function.\n",
	)
	}

	#[cold]
	pub(crate) fn default_extern_query(name: &str, key: &dyn std::fmt::Debug) -> ! {
	bug!(
	"`tcx.{name}({key:?})` unsupported by its crate; \
	perhaps the `{name}` query was never assigned a provider function",
	)
	}