Auto merge of #103723 - CastilloDel:master, r=jackh726

Remove allow(rustc::potential_query_instability) in rustc_trait_selection

Related to https://github.com/rust-lang/rust/issues/84447

This PR needs to be benchmarked to check for regressions.

compiler/rustc_trait_selection/src/lib.rs

@@ -10,7 +10,6 @@
 //!
 //! This API is completely unstable and subject to change.
 
-#![allow(rustc::potential_query_instability)]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(box_patterns)]
 #![feature(control_flow_enum)]

compiler/rustc_trait_selection/src/traits/auto_trait.rs

@@ -12,7 +12,7 @@ use rustc_middle::ty::fold::{TypeFolder, TypeSuperFoldable};
 use rustc_middle::ty::visit::TypeVisitable;
 use rustc_middle::ty::{PolyTraitRef, Region, RegionVid};
 
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
 
 use std::collections::hash_map::Entry;
 use std::collections::VecDeque;
@@ -27,8 +27,8 @@ pub enum RegionTarget<'tcx> {
 
 #[derive(Default, Debug, Clone)]
 pub struct RegionDeps<'tcx> {
-    larger: FxHashSet<RegionTarget<'tcx>>,
-    smaller: FxHashSet<RegionTarget<'tcx>>,
+    larger: FxIndexSet<RegionTarget<'tcx>>,
+    smaller: FxIndexSet<RegionTarget<'tcx>>,
 }
 
 pub enum AutoTraitResult<A> {
@@ -266,7 +266,7 @@ impl<'tcx> AutoTraitFinder<'tcx> {
         }));
 
         let computed_preds = param_env.caller_bounds().iter();
-        let mut user_computed_preds: FxHashSet<_> = user_env.caller_bounds().iter().collect();
+        let mut user_computed_preds: FxIndexSet<_> = user_env.caller_bounds().iter().collect();
 
         let mut new_env = param_env;
         let dummy_cause = ObligationCause::dummy();
@@ -389,7 +389,7 @@ impl<'tcx> AutoTraitFinder<'tcx> {
     /// not just one specific lifetime (e.g., `'static`).
     fn add_user_pred(
         &self,
-        user_computed_preds: &mut FxHashSet<ty::Predicate<'tcx>>,
+        user_computed_preds: &mut FxIndexSet<ty::Predicate<'tcx>>,
         new_pred: ty::Predicate<'tcx>,
     ) {
         let mut should_add_new = true;
@@ -585,7 +585,7 @@ impl<'tcx> AutoTraitFinder<'tcx> {
         &self,
         ty: Ty<'_>,
         nested: impl Iterator<Item = Obligation<'tcx, ty::Predicate<'tcx>>>,
-        computed_preds: &mut FxHashSet<ty::Predicate<'tcx>>,
+        computed_preds: &mut FxIndexSet<ty::Predicate<'tcx>>,
         fresh_preds: &mut FxHashSet<ty::Predicate<'tcx>>,
         predicates: &mut VecDeque<ty::PolyTraitPredicate<'tcx>>,
         select: &mut SelectionContext<'_, 'tcx>,

compiler/rustc_trait_selection/src/traits/engine.rs

@@ -4,7 +4,7 @@ use std::fmt::Debug;
 use super::TraitEngine;
 use super::{ChalkFulfillmentContext, FulfillmentContext};
 use crate::infer::InferCtxtExt;
-use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::fx::FxIndexSet;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_infer::infer::at::ToTrace;
 use rustc_infer::infer::canonical::{
@@ -154,10 +154,10 @@ impl<'a, 'tcx> ObligationCtxt<'a, 'tcx> {
         param_env: ty::ParamEnv<'tcx>,
         span: Span,
         def_id: LocalDefId,
-    ) -> FxHashSet<Ty<'tcx>> {
+    ) -> FxIndexSet<Ty<'tcx>> {
         let tcx = self.infcx.tcx;
         let assumed_wf_types = tcx.assumed_wf_types(def_id);
-        let mut implied_bounds = FxHashSet::default();
+        let mut implied_bounds = FxIndexSet::default();
         let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
         let cause = ObligationCause::misc(span, hir_id);
         for ty in assumed_wf_types {

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -15,7 +15,7 @@ use crate::traits::query::normalize::AtExt as _;
 use crate::traits::specialize::to_pretty_impl_header;
 use on_unimplemented::OnUnimplementedNote;
 use on_unimplemented::TypeErrCtxtExt as _;
-use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
 use rustc_errors::{
     pluralize, struct_span_err, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed,
     MultiSpan, Style,
@@ -379,7 +379,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             index: Option<usize>, // None if this is an old error
         }
 
-        let mut error_map: FxHashMap<_, Vec<_>> = self
+        let mut error_map: FxIndexMap<_, Vec<_>> = self
             .reported_trait_errors
             .borrow()
             .iter()

compiler/rustc_trait_selection/src/traits/outlives_bounds.rs

@@ -2,7 +2,7 @@ use crate::infer::InferCtxt;
 use crate::traits::query::type_op::{self, TypeOp, TypeOpOutput};
 use crate::traits::query::NoSolution;
 use crate::traits::ObligationCause;
-use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::fx::FxIndexSet;
 use rustc_hir as hir;
 use rustc_hir::HirId;
 use rustc_middle::ty::{self, ParamEnv, Ty};
@@ -22,7 +22,7 @@ pub trait InferCtxtExt<'a, 'tcx> {
         &'a self,
         param_env: ty::ParamEnv<'tcx>,
         body_id: hir::HirId,
-        tys: FxHashSet<Ty<'tcx>>,
+        tys: FxIndexSet<Ty<'tcx>>,
     ) -> Bounds<'a, 'tcx>;
 }
 
@@ -103,7 +103,7 @@ impl<'a, 'tcx: 'a> InferCtxtExt<'a, 'tcx> for InferCtxt<'tcx> {
         &'a self,
         param_env: ParamEnv<'tcx>,
         body_id: HirId,
-        tys: FxHashSet<Ty<'tcx>>,
+        tys: FxIndexSet<Ty<'tcx>>,
     ) -> Bounds<'a, 'tcx> {
         tys.into_iter()
             .map(move |ty| {

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -2,6 +2,12 @@
 //!
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/resolution.html#selection
 
+// FIXME: The `map` field in ProvisionalEvaluationCache should be changed to
+// a `FxIndexMap` to avoid query instability, but right now it causes a perf regression. This would be
+// fixed or at least lightened by the addition of the `drain_filter` method to `FxIndexMap`
+// Relevant: https://github.com/rust-lang/rust/pull/103723 and https://github.com/bluss/indexmap/issues/242
+#![allow(rustc::potential_query_instability)]
+
 use self::EvaluationResult::*;
 use self::SelectionCandidate::*;
 
@@ -24,7 +30,8 @@ use crate::traits::error_reporting::TypeErrCtxtExt;
 use crate::traits::project::ProjectAndUnifyResult;
 use crate::traits::project::ProjectionCacheKeyExt;
 use crate::traits::ProjectionCacheKey;
-use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
+use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_errors::{Diagnostic, ErrorGuaranteed};
 use rustc_hir as hir;

compiler/rustc_trait_selection/src/traits/specialize/mod.rs

@@ -16,7 +16,7 @@ use crate::errors::NegativePositiveConflict;
 use crate::infer::{InferCtxt, InferOk, TyCtxtInferExt};
 use crate::traits::select::IntercrateAmbiguityCause;
 use crate::traits::{self, coherence, FutureCompatOverlapErrorKind, ObligationCause};
-use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
+use rustc_data_structures::fx::FxIndexSet;
 use rustc_errors::{struct_span_err, DiagnosticBuilder, EmissionGuarantee};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::ty::{self, ImplSubject, TyCtxt};
@@ -435,7 +435,7 @@ pub(crate) fn to_pretty_impl_header(tcx: TyCtxt<'_>, impl_def_id: DefId) -> Opti
 
     // FIXME: Currently only handles ?Sized.
     //        Needs to support ?Move and ?DynSized when they are implemented.
-    let mut types_without_default_bounds = FxHashSet::default();
+    let mut types_without_default_bounds = FxIndexSet::default();
     let sized_trait = tcx.lang_items().sized_trait();
 
     if !substs.is_empty() {