Reduce generics use in the query system.

`QueryStackFrame<I>` is a generic type, and the `I` parameter leaks out
to many other related types. However, it only has two instantiations in
practice:
- `QueryStackFrame<QueryStackFrameExtra>`
- `QueryStackFrame<QueryStackDeferred<'tcx>>`

And most of the places that currently use `QueryStackFrame<I>` are
actually specific to one of the instantiations. This commit removes the
unneeded genericity.

The following types are only ever used with `QueryStackDeferred<'tcx>`:
- QueryMap
- QueryJobInfo
- QueryJob
- QueryWaiter
- QueryLatchInfo
- QueryLatch
- QueryState
- QueryResult
and their `<I>` parameter is changed to `<'tcx>`.

Also, the `QueryContext::QueryInfo` associated type is removed.

`CycleError<I>` and `QueryInfo<I>` are still generic over type, because
they are used with both instantiations.

This required also adding a `<'tcx>` parameter to the traits
`QueryDispatcher` and `QueryContext`, which is annoying but I can't see
how to avoid it.

Author: nnethercote

compiler/rustc_middle/src/query/mod.rs

@@ -88,7 +88,7 @@ use rustc_index::IndexVec;
 use rustc_lint_defs::LintId;
 use rustc_macros::rustc_queries;
 use rustc_query_system::ich::StableHashingContext;
-use rustc_query_system::query::{QueryMode, QueryStackDeferred, QueryState};
+use rustc_query_system::query::{QueryMode, QueryState};
 use rustc_session::Limits;
 use rustc_session::config::{EntryFnType, OptLevel, OutputFilenames, SymbolManglingVersion};
 use rustc_session::cstore::{

compiler/rustc_middle/src/query/plumbing.rs

@@ -440,7 +440,7 @@ macro_rules! define_callbacks {
         #[derive(Default)]
         pub struct QueryStates<'tcx> {
             $(
-                pub $name: QueryState<$($K)*, QueryStackDeferred<'tcx>>,
+                pub $name: QueryState<'tcx, $($K)*>,
             )*
         }
 

compiler/rustc_query_impl/src/lib.rs

@@ -21,7 +21,7 @@ use rustc_query_system::dep_graph::SerializedDepNodeIndex;
 use rustc_query_system::ich::StableHashingContext;
 use rustc_query_system::query::{
     CycleError, CycleErrorHandling, HashResult, QueryCache, QueryDispatcher, QueryMap, QueryMode,
-    QueryStackDeferred, QueryState, get_query_incr, get_query_non_incr,
+    QueryState, get_query_incr, get_query_non_incr,
 };
 use rustc_span::{ErrorGuaranteed, Span};
 
@@ -66,7 +66,7 @@ impl<'tcx, C: QueryCache, const ANON: bool, const DEPTH_LIMIT: bool, const FEEDA
 
 // This is `impl QueryDispatcher for SemiDynamicQueryDispatcher`.
 impl<'tcx, C: QueryCache, const ANON: bool, const DEPTH_LIMIT: bool, const FEEDABLE: bool>
-    QueryDispatcher for SemiDynamicQueryDispatcher<'tcx, C, ANON, DEPTH_LIMIT, FEEDABLE>
+    QueryDispatcher<'tcx> for SemiDynamicQueryDispatcher<'tcx, C, ANON, DEPTH_LIMIT, FEEDABLE>
 where
     for<'a> C::Key: HashStable<StableHashingContext<'a>>,
 {
@@ -86,10 +86,7 @@ where
     }
 
     #[inline(always)]
-    fn query_state<'a>(
-        self,
-        qcx: QueryCtxt<'tcx>,
-    ) -> &'a QueryState<Self::Key, QueryStackDeferred<'tcx>>
+    fn query_state<'a>(self, qcx: QueryCtxt<'tcx>) -> &'a QueryState<'tcx, Self::Key>
     where
         QueryCtxt<'tcx>: 'a,
     {
@@ -98,7 +95,7 @@ where
         unsafe {
             &*(&qcx.tcx.query_system.states as *const QueryStates<'tcx>)
                 .byte_add(self.vtable.query_state)
-                .cast::<QueryState<Self::Key, QueryStackDeferred<'tcx>>>()
+                .cast::<QueryState<'tcx, Self::Key>>()
         }
     }
 
@@ -211,13 +208,15 @@ where
 /// on the type `rustc_query_impl::query_impl::$name::QueryType`.
 trait QueryDispatcherUnerased<'tcx> {
     type UnerasedValue;
-    type Dispatcher: QueryDispatcher<Qcx = QueryCtxt<'tcx>>;
+    type Dispatcher: QueryDispatcher<'tcx, Qcx = QueryCtxt<'tcx>>;
 
     const NAME: &'static &'static str;
 
     fn query_dispatcher(tcx: TyCtxt<'tcx>) -> Self::Dispatcher;
 
-    fn restore_val(value: <Self::Dispatcher as QueryDispatcher>::Value) -> Self::UnerasedValue;
+    fn restore_val(
+        value: <Self::Dispatcher as QueryDispatcher<'tcx>>::Value,
+    ) -> Self::UnerasedValue;
 }
 
 pub fn query_system<'a>(

compiler/rustc_query_impl/src/plumbing.rs

@@ -60,9 +60,7 @@ impl<'tcx> HasDepContext for QueryCtxt<'tcx> {
     }
 }
 
-impl<'tcx> QueryContext for QueryCtxt<'tcx> {
-    type QueryInfo = QueryStackDeferred<'tcx>;
-
+impl<'tcx> QueryContext<'tcx> for QueryCtxt<'tcx> {
     #[inline]
     fn jobserver_proxy(&self) -> &Proxy {
         &self.tcx.jobserver_proxy
@@ -93,10 +91,7 @@ impl<'tcx> QueryContext for QueryCtxt<'tcx> {
     /// Prefer passing `false` to `require_complete` to avoid potential deadlocks,
     /// especially when called from within a deadlock handler, unless a
     /// complete map is needed and no deadlock is possible at this call site.
-    fn collect_active_jobs(
-        self,
-        require_complete: bool,
-    ) -> Result<QueryMap<QueryStackDeferred<'tcx>>, QueryMap<QueryStackDeferred<'tcx>>> {
+    fn collect_active_jobs(self, require_complete: bool) -> Result<QueryMap<'tcx>, QueryMap<'tcx>> {
         let mut jobs = QueryMap::default();
         let mut complete = true;
 
@@ -415,7 +410,7 @@ pub(crate) fn encode_query_results<'a, 'tcx, Q>(
 }
 
 pub(crate) fn query_key_hash_verify<'tcx>(
-    query: impl QueryDispatcher<Qcx = QueryCtxt<'tcx>>,
+    query: impl QueryDispatcher<'tcx, Qcx = QueryCtxt<'tcx>>,
     qcx: QueryCtxt<'tcx>,
 ) {
     let _timer = qcx.tcx.prof.generic_activity_with_arg("query_key_hash_verify_for", query.name());
@@ -443,7 +438,7 @@ pub(crate) fn query_key_hash_verify<'tcx>(
 
 fn try_load_from_on_disk_cache<'tcx, Q>(query: Q, tcx: TyCtxt<'tcx>, dep_node: DepNode)
 where
-    Q: QueryDispatcher<Qcx = QueryCtxt<'tcx>>,
+    Q: QueryDispatcher<'tcx, Qcx = QueryCtxt<'tcx>>,
 {
     debug_assert!(tcx.dep_graph.is_green(&dep_node));
 
@@ -489,7 +484,7 @@ where
 
 fn force_from_dep_node<'tcx, Q>(query: Q, tcx: TyCtxt<'tcx>, dep_node: DepNode) -> bool
 where
-    Q: QueryDispatcher<Qcx = QueryCtxt<'tcx>>,
+    Q: QueryDispatcher<'tcx, Qcx = QueryCtxt<'tcx>>,
 {
     // We must avoid ever having to call `force_from_dep_node()` for a
     // `DepNode::codegen_unit`:
@@ -732,14 +727,14 @@ macro_rules! define_queries {
                 }
 
                 #[inline(always)]
-                fn restore_val(value: <Self::Dispatcher as QueryDispatcher>::Value) -> Self::UnerasedValue {
+                fn restore_val(value: <Self::Dispatcher as QueryDispatcher<'tcx>>::Value) -> Self::UnerasedValue {
                     erase::restore_val::<queries::$name::Value<'tcx>>(value)
                 }
             }
 
             pub(crate) fn collect_active_jobs<'tcx>(
                 tcx: TyCtxt<'tcx>,
-                qmap: &mut QueryMap<QueryStackDeferred<'tcx>>,
+                qmap: &mut QueryMap<'tcx>,
                 require_complete: bool,
             ) -> Option<()> {
                 let make_query = |tcx, key| {
@@ -823,7 +818,7 @@ macro_rules! define_queries {
         // These arrays are used for iteration and can't be indexed by `DepKind`.
 
         const COLLECT_ACTIVE_JOBS: &[
-            for<'tcx> fn(TyCtxt<'tcx>, &mut QueryMap<QueryStackDeferred<'tcx>>, bool) -> Option<()>
+            for<'tcx> fn(TyCtxt<'tcx>, &mut QueryMap<'tcx>, bool) -> Option<()>
         ] =
             &[$(query_impl::$name::collect_active_jobs),*];
 

compiler/rustc_query_system/src/dep_graph/graph.rs

@@ -519,7 +519,11 @@ impl<D: Deps> DepGraph<D> {
     /// This encodes a diagnostic by creating a node with an unique index and associating
     /// `diagnostic` with it, for use in the next session.
     #[inline]
-    pub fn record_diagnostic<Qcx: QueryContext>(&self, qcx: Qcx, diagnostic: &DiagInner) {
+    pub fn record_diagnostic<'tcx, Qcx: QueryContext<'tcx>>(
+        &self,
+        qcx: Qcx,
+        diagnostic: &DiagInner,
+    ) {
         if let Some(ref data) = self.data {
             D::read_deps(|task_deps| match task_deps {
                 TaskDepsRef::EvalAlways | TaskDepsRef::Ignore => return,
@@ -532,7 +536,7 @@ impl<D: Deps> DepGraph<D> {
     /// This forces a diagnostic node green by running its side effect. `prev_index` would
     /// refer to a node created used `encode_diagnostic` in the previous session.
     #[inline]
-    pub fn force_diagnostic_node<Qcx: QueryContext>(
+    pub fn force_diagnostic_node<'tcx, Qcx: QueryContext<'tcx>>(
         &self,
         qcx: Qcx,
         prev_index: SerializedDepNodeIndex,
@@ -669,7 +673,7 @@ impl<D: Deps> DepGraphData<D> {
     /// This encodes a diagnostic by creating a node with an unique index and associating
     /// `diagnostic` with it, for use in the next session.
     #[inline]
-    fn encode_diagnostic<Qcx: QueryContext>(
+    fn encode_diagnostic<'tcx, Qcx: QueryContext<'tcx>>(
         &self,
         qcx: Qcx,
         diagnostic: &DiagInner,
@@ -693,7 +697,7 @@ impl<D: Deps> DepGraphData<D> {
     /// This forces a diagnostic node green by running its side effect. `prev_index` would
     /// refer to a node created used `encode_diagnostic` in the previous session.
     #[inline]
-    fn force_diagnostic_node<Qcx: QueryContext>(
+    fn force_diagnostic_node<'tcx, Qcx: QueryContext<'tcx>>(
         &self,
         qcx: Qcx,
         prev_index: SerializedDepNodeIndex,
@@ -843,7 +847,7 @@ impl<D: Deps> DepGraph<D> {
         DepNodeColor::Unknown
     }
 
-    pub fn try_mark_green<Qcx: QueryContext<Deps = D>>(
+    pub fn try_mark_green<'tcx, Qcx: QueryContext<'tcx, Deps = D>>(
         &self,
         qcx: Qcx,
         dep_node: &DepNode,
@@ -858,7 +862,7 @@ impl<D: Deps> DepGraphData<D> {
     /// A node will have an index, when it's already been marked green, or when we can mark it
     /// green. This function will mark the current task as a reader of the specified node, when
     /// a node index can be found for that node.
-    pub(crate) fn try_mark_green<Qcx: QueryContext<Deps = D>>(
+    pub(crate) fn try_mark_green<'tcx, Qcx: QueryContext<'tcx, Deps = D>>(
         &self,
         qcx: Qcx,
         dep_node: &DepNode,
@@ -883,7 +887,7 @@ impl<D: Deps> DepGraphData<D> {
     }
 
     #[instrument(skip(self, qcx, parent_dep_node_index, frame), level = "debug")]
-    fn try_mark_parent_green<Qcx: QueryContext<Deps = D>>(
+    fn try_mark_parent_green<'tcx, Qcx: QueryContext<'tcx, Deps = D>>(
         &self,
         qcx: Qcx,
         parent_dep_node_index: SerializedDepNodeIndex,
@@ -973,7 +977,7 @@ impl<D: Deps> DepGraphData<D> {
 
     /// Try to mark a dep-node which existed in the previous compilation session as green.
     #[instrument(skip(self, qcx, prev_dep_node_index, frame), level = "debug")]
-    fn try_mark_previous_green<Qcx: QueryContext<Deps = D>>(
+    fn try_mark_previous_green<'tcx, Qcx: QueryContext<'tcx, Deps = D>>(
         &self,
         qcx: Qcx,
         prev_dep_node_index: SerializedDepNodeIndex,

compiler/rustc_query_system/src/query/dispatcher.rs

@@ -14,8 +14,8 @@ pub type HashResult<V> = Option<fn(&mut StableHashingContext<'_>, &V) -> Fingerp
 
 /// Unambiguous shorthand for `<This::Qcx as HasDepContext>::DepContext`.
 #[expect(type_alias_bounds)]
-type DepContextOf<This: QueryDispatcher> =
-    <<This as QueryDispatcher>::Qcx as HasDepContext>::DepContext;
+type DepContextOf<'tcx, This: QueryDispatcher<'tcx>> =
+    <<This as QueryDispatcher<'tcx>>::Qcx as HasDepContext>::DepContext;
 
 /// Trait that can be used as a vtable for a single query, providing operations
 /// and metadata for that query.
@@ -25,34 +25,31 @@ type DepContextOf<This: QueryDispatcher> =
 /// Those types are not visible from this `rustc_query_system` crate.
 ///
 /// "Dispatcher" should be understood as a near-synonym of "vtable".
-pub trait QueryDispatcher: Copy {
+pub trait QueryDispatcher<'tcx>: Copy {
     fn name(self) -> &'static str;
 
     /// Query context used by this dispatcher, i.e. `rustc_query_impl::QueryCtxt`.
-    type Qcx: QueryContext;
+    type Qcx: QueryContext<'tcx>;
 
     // `Key` and `Value` are `Copy` instead of `Clone` to ensure copying them stays cheap,
     // but it isn't necessary.
-    type Key: DepNodeParams<DepContextOf<Self>> + Eq + Hash + Copy + Debug;
+    type Key: DepNodeParams<DepContextOf<'tcx, Self>> + Eq + Hash + Copy + Debug;
     type Value: Copy;
 
     type Cache: QueryCache<Key = Self::Key, Value = Self::Value>;
 
     fn format_value(self) -> fn(&Self::Value) -> String;
 
     // Don't use this method to access query results, instead use the methods on TyCtxt
-    fn query_state<'a>(
-        self,
-        tcx: Self::Qcx,
-    ) -> &'a QueryState<Self::Key, <Self::Qcx as QueryContext>::QueryInfo>;
+    fn query_state<'a>(self, tcx: Self::Qcx) -> &'a QueryState<'tcx, Self::Key>;
 
     // Don't use this method to access query results, instead use the methods on TyCtxt
     fn query_cache<'a>(self, tcx: Self::Qcx) -> &'a Self::Cache;
 
-    fn cache_on_disk(self, tcx: DepContextOf<Self>, key: &Self::Key) -> bool;
+    fn cache_on_disk(self, tcx: DepContextOf<'tcx, Self>, key: &Self::Key) -> bool;
 
     // Don't use this method to compute query results, instead use the methods on TyCtxt
-    fn execute_query(self, tcx: DepContextOf<Self>, k: Self::Key) -> Self::Value;
+    fn execute_query(self, tcx: DepContextOf<'tcx, Self>, k: Self::Key) -> Self::Value;
 
     fn compute(self, tcx: Self::Qcx, key: Self::Key) -> Self::Value;
 
@@ -74,7 +71,7 @@ pub trait QueryDispatcher: Copy {
     /// Synthesize an error value to let compilation continue after a cycle.
     fn value_from_cycle_error(
         self,
-        tcx: DepContextOf<Self>,
+        tcx: DepContextOf<'tcx, Self>,
         cycle_error: &CycleError<QueryStackFrameExtra>,
         guar: ErrorGuaranteed,
     ) -> Self::Value;
@@ -89,7 +86,7 @@ pub trait QueryDispatcher: Copy {
     fn hash_result(self) -> HashResult<Self::Value>;
 
     // Just here for convenience and checking that the key matches the kind, don't override this.
-    fn construct_dep_node(self, tcx: DepContextOf<Self>, key: &Self::Key) -> DepNode {
+    fn construct_dep_node(self, tcx: DepContextOf<'tcx, Self>, key: &Self::Key) -> DepNode {
         DepNode::construct(tcx, self.dep_kind(), key)
     }
 }