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Auto merge of rust-lang#124203 - lukas-code:delete-deleting-caches, r=compiler-errors
fix normalizing in different `ParamEnv`s with the same `InferCtxt` This PR changes the key of the projection cache from just `AliasTy` to `(AliasTy, ParamEnv)` to allow normalizing in different `ParamEnv`s without resetting caches. Previously, normalizing the same alias in different param envs would always reuse the cached result from the first normalization, which is incorrect if the projection clauses in the param env have changed. Fixing this bug allows us to get rid of `InferCtxt::clear_caches`, which was only used by the `AutoTraitFinder`, because it requires normalizing in different param envs. r? `@fmease`
2 parents f22a0c2 + 5a2b335 commit 1b3fba0

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8 files changed

+25
-29
lines changed

8 files changed

+25
-29
lines changed

‎compiler/rustc_hir_analysis/src/collect/item_bounds.rs

+2-2
Original file line numberDiff line numberDiff line change
@@ -4,7 +4,7 @@ use rustc_data_structures::fx::FxIndexSet;
44
use rustc_hir as hir;
55
use rustc_infer::traits::util;
66
use rustc_middle::ty::GenericArgs;
7-
use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeFolder};
7+
use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable};
88
use rustc_span::def_id::{DefId, LocalDefId};
99
use rustc_span::Span;
1010

@@ -214,7 +214,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for AssocTyToOpaque<'tcx> {
214214
{
215215
self.tcx.type_of(projection_ty.def_id).instantiate(self.tcx, projection_ty.args)
216216
} else {
217-
ty
217+
ty.super_fold_with(self)
218218
}
219219
}
220220
}

‎compiler/rustc_infer/src/infer/mod.rs

-9
Original file line numberDiff line numberDiff line change
@@ -1521,15 +1521,6 @@ impl<'tcx> InferCtxt<'tcx> {
15211521
closure_kind_ty.to_opt_closure_kind()
15221522
}
15231523

1524-
/// Clears the selection, evaluation, and projection caches. This is useful when
1525-
/// repeatedly attempting to select an `Obligation` while changing only
1526-
/// its `ParamEnv`, since `FulfillmentContext` doesn't use probing.
1527-
pub fn clear_caches(&self) {
1528-
self.selection_cache.clear();
1529-
self.evaluation_cache.clear();
1530-
self.inner.borrow_mut().projection_cache().clear();
1531-
}
1532-
15331524
pub fn universe(&self) -> ty::UniverseIndex {
15341525
self.universe.get()
15351526
}

‎compiler/rustc_infer/src/traits/project.rs

+3-2
Original file line numberDiff line numberDiff line change
@@ -78,11 +78,12 @@ pub struct ProjectionCacheStorage<'tcx> {
7878
#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
7979
pub struct ProjectionCacheKey<'tcx> {
8080
ty: ty::AliasTy<'tcx>,
81+
param_env: ty::ParamEnv<'tcx>,
8182
}
8283

8384
impl<'tcx> ProjectionCacheKey<'tcx> {
84-
pub fn new(ty: ty::AliasTy<'tcx>) -> Self {
85-
Self { ty }
85+
pub fn new(ty: ty::AliasTy<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Self {
86+
Self { ty, param_env }
8687
}
8788
}
8889

‎compiler/rustc_trait_selection/src/traits/auto_trait.rs

-5
Original file line numberDiff line numberDiff line change
@@ -152,7 +152,6 @@ impl<'tcx> AutoTraitFinder<'tcx> {
152152
with {:?}",
153153
trait_ref, full_env
154154
);
155-
infcx.clear_caches();
156155

157156
// At this point, we already have all of the bounds we need. FulfillmentContext is used
158157
// to store all of the necessary region/lifetime bounds in the InferContext, as well as
@@ -176,9 +175,7 @@ impl<'tcx> AutoTraitFinder<'tcx> {
176175

177176
AutoTraitResult::PositiveImpl(auto_trait_callback(info))
178177
}
179-
}
180178

181-
impl<'tcx> AutoTraitFinder<'tcx> {
182179
/// The core logic responsible for computing the bounds for our synthesized impl.
183180
///
184181
/// To calculate the bounds, we call `SelectionContext.select` in a loop. Like
@@ -255,8 +252,6 @@ impl<'tcx> AutoTraitFinder<'tcx> {
255252
let dummy_cause = ObligationCause::dummy();
256253

257254
while let Some(pred) = predicates.pop_front() {
258-
infcx.clear_caches();
259-
260255
if !already_visited.insert(pred) {
261256
continue;
262257
}

‎compiler/rustc_trait_selection/src/traits/fulfill.rs

+2-2
Original file line numberDiff line numberDiff line change
@@ -758,9 +758,9 @@ impl<'a, 'tcx> FulfillProcessor<'a, 'tcx> {
758758
// no type variables present, can use evaluation for better caching.
759759
// FIXME: consider caching errors too.
760760
if self.selcx.infcx.predicate_must_hold_considering_regions(obligation) {
761-
if let Some(key) = ProjectionCacheKey::from_poly_projection_predicate(
761+
if let Some(key) = ProjectionCacheKey::from_poly_projection_obligation(
762762
&mut self.selcx,
763-
project_obligation.predicate,
763+
&project_obligation,
764764
) {
765765
// If `predicate_must_hold_considering_regions` succeeds, then we've
766766
// evaluated all sub-obligations. We can therefore mark the 'root'

‎compiler/rustc_trait_selection/src/traits/project.rs

+7-6
Original file line numberDiff line numberDiff line change
@@ -344,7 +344,7 @@ pub(super) fn opt_normalize_projection_type<'a, 'b, 'tcx>(
344344
let use_cache = !selcx.is_intercrate();
345345

346346
let projection_ty = infcx.resolve_vars_if_possible(projection_ty);
347-
let cache_key = ProjectionCacheKey::new(projection_ty);
347+
let cache_key = ProjectionCacheKey::new(projection_ty, param_env);
348348

349349
// FIXME(#20304) For now, I am caching here, which is good, but it
350350
// means we don't capture the type variables that are created in
@@ -2105,27 +2105,28 @@ fn assoc_ty_own_obligations<'cx, 'tcx>(
21052105
}
21062106

21072107
pub(crate) trait ProjectionCacheKeyExt<'cx, 'tcx>: Sized {
2108-
fn from_poly_projection_predicate(
2108+
fn from_poly_projection_obligation(
21092109
selcx: &mut SelectionContext<'cx, 'tcx>,
2110-
predicate: ty::PolyProjectionPredicate<'tcx>,
2110+
obligation: &PolyProjectionObligation<'tcx>,
21112111
) -> Option<Self>;
21122112
}
21132113

21142114
impl<'cx, 'tcx> ProjectionCacheKeyExt<'cx, 'tcx> for ProjectionCacheKey<'tcx> {
2115-
fn from_poly_projection_predicate(
2115+
fn from_poly_projection_obligation(
21162116
selcx: &mut SelectionContext<'cx, 'tcx>,
2117-
predicate: ty::PolyProjectionPredicate<'tcx>,
2117+
obligation: &PolyProjectionObligation<'tcx>,
21182118
) -> Option<Self> {
21192119
let infcx = selcx.infcx;
21202120
// We don't do cross-snapshot caching of obligations with escaping regions,
21212121
// so there's no cache key to use
2122-
predicate.no_bound_vars().map(|predicate| {
2122+
obligation.predicate.no_bound_vars().map(|predicate| {
21232123
ProjectionCacheKey::new(
21242124
// We don't attempt to match up with a specific type-variable state
21252125
// from a specific call to `opt_normalize_projection_type` - if
21262126
// there's no precise match, the original cache entry is "stranded"
21272127
// anyway.
21282128
infcx.resolve_vars_if_possible(predicate.projection_ty),
2129+
obligation.param_env,
21292130
)
21302131
})
21312132
}

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

+7-3
Original file line numberDiff line numberDiff line change
@@ -815,7 +815,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
815815
// `EvaluatedToOkModuloRegions`), and skip re-evaluating the
816816
// sub-obligations.
817817
if let Some(key) =
818-
ProjectionCacheKey::from_poly_projection_predicate(self, data)
818+
ProjectionCacheKey::from_poly_projection_obligation(
819+
self,
820+
&project_obligation,
821+
)
819822
{
820823
if let Some(cached_res) = self
821824
.infcx
@@ -844,8 +847,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
844847
&& (eval_rslt == EvaluatedToOk
845848
|| eval_rslt == EvaluatedToOkModuloRegions)
846849
&& let Some(key) =
847-
ProjectionCacheKey::from_poly_projection_predicate(
848-
self, data,
850+
ProjectionCacheKey::from_poly_projection_obligation(
851+
self,
852+
&project_obligation,
849853
)
850854
{
851855
// If the result is something that we can cache, then mark this

‎tests/ui/impl-trait/in-trait/nested-rpitit-bounds.rs

+4
Original file line numberDiff line numberDiff line change
@@ -6,6 +6,10 @@ trait Foo {
66
fn foo() -> impl Deref<Target = impl Deref<Target = impl Sized>> {
77
&&()
88
}
9+
10+
fn bar() -> impl Deref<Target = Option<impl Sized>> {
11+
&Some(())
12+
}
913
}
1014

1115
fn main() {}

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