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skinnyBatlcnr
skinnyBat
authored and
lcnr
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Assume unevaluated consts are equal to the other consts and add ConstEquate obligation. This delays
the need to evaluate consts eagerly and therefore gets around const eval query cycles.
1 parent 09739c2 commit 8b14b84

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36 files changed

+371
-122
lines changed

36 files changed

+371
-122
lines changed

‎src/librustc_infer/infer/canonical/query_response.rs‎

Lines changed: 8 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -25,7 +25,7 @@ use rustc_middle::arena::ArenaAllocatable;
2525
use rustc_middle::ty::fold::TypeFoldable;
2626
use rustc_middle::ty::relate::TypeRelation;
2727
use rustc_middle::ty::subst::{GenericArg, GenericArgKind};
28-
use rustc_middle::ty::{self, BoundVar, Ty, TyCtxt};
28+
use rustc_middle::ty::{self, BoundVar, Const, Ty, TyCtxt};
2929
use std::fmt::Debug;
3030

3131
impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
@@ -671,6 +671,13 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for QueryTypeRelatingDelegate<'_, 'tcx> {
671671
});
672672
}
673673

674+
fn const_equate(&mut self, _a: &'tcx Const<'tcx>, _b: &'tcx Const<'tcx>) {
675+
span_bug!(
676+
self.cause.span(self.infcx.tcx),
677+
"lazy_normalization_consts: unreachable `const_equate`"
678+
);
679+
}
680+
674681
fn normalization() -> NormalizationStrategy {
675682
NormalizationStrategy::Eager
676683
}

‎src/librustc_infer/infer/combine.rs‎

Lines changed: 15 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -164,7 +164,6 @@ impl<'infcx, 'tcx> InferCtxt<'infcx, 'tcx> {
164164
(_, ty::ConstKind::Infer(InferConst::Var(vid))) => {
165165
return self.unify_const_variable(!a_is_expected, vid, a);
166166
}
167-
168167
_ => {}
169168
}
170169

@@ -375,6 +374,20 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
375374
debug!("generalize: success {{ {:?}, {:?} }}", ty, needs_wf);
376375
Ok(Generalization { ty, needs_wf })
377376
}
377+
378+
pub fn add_const_equate_obligation(
379+
&mut self,
380+
a_is_expected: bool,
381+
a: &'tcx ty::Const<'tcx>,
382+
b: &'tcx ty::Const<'tcx>,
383+
) {
384+
let predicate = if a_is_expected {
385+
ty::Predicate::ConstEquate(a, b)
386+
} else {
387+
ty::Predicate::ConstEquate(b, a)
388+
};
389+
self.obligations.push(Obligation::new(self.trace.cause.clone(), self.param_env, predicate));
390+
}
378391
}
379392

380393
struct Generalizer<'cx, 'tcx> {
@@ -637,6 +650,7 @@ impl TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
637650
}
638651
}
639652
}
653+
ty::ConstKind::Unevaluated(..) => Ok(c),
640654
_ => relate::super_relate_consts(self, c, c),
641655
}
642656
}

‎src/librustc_infer/infer/equate.rs‎

Lines changed: 12 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -4,7 +4,7 @@ use super::Subtype;
44
use rustc_middle::ty::relate::{self, Relate, RelateResult, TypeRelation};
55
use rustc_middle::ty::subst::SubstsRef;
66
use rustc_middle::ty::TyVar;
7-
use rustc_middle::ty::{self, Ty, TyCtxt};
7+
use rustc_middle::ty::{self, ConstKind, Ty, TyCtxt};
88

99
use rustc_hir::def_id::DefId;
1010

@@ -119,7 +119,17 @@ impl TypeRelation<'tcx> for Equate<'combine, 'infcx, 'tcx> {
119119
a: &'tcx ty::Const<'tcx>,
120120
b: &'tcx ty::Const<'tcx>,
121121
) -> RelateResult<'tcx, &'tcx ty::Const<'tcx>> {
122-
self.fields.infcx.super_combine_consts(self, a, b)
122+
match (a.val, b.val) {
123+
(ConstKind::Unevaluated(..), _) => {
124+
self.fields.add_const_equate_obligation(self.a_is_expected, a, b);
125+
Ok(b)
126+
}
127+
(_, ConstKind::Unevaluated(..)) => {
128+
self.fields.add_const_equate_obligation(self.a_is_expected, a, b);
129+
Ok(a)
130+
}
131+
_ => self.fields.infcx.super_combine_consts(self, a, b),
132+
}
123133
}
124134

125135
fn binders<T>(

‎src/librustc_infer/infer/glb.rs‎

Lines changed: 11 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -79,7 +79,17 @@ impl TypeRelation<'tcx> for Glb<'combine, 'infcx, 'tcx> {
7979
a: &'tcx ty::Const<'tcx>,
8080
b: &'tcx ty::Const<'tcx>,
8181
) -> RelateResult<'tcx, &'tcx ty::Const<'tcx>> {
82-
self.fields.infcx.super_combine_consts(self, a, b)
82+
match (a.val, b.val) {
83+
(ty::ConstKind::Unevaluated(..), _) => {
84+
self.fields.add_const_equate_obligation(self.a_is_expected, a, b);
85+
Ok(b)
86+
}
87+
(_, ty::ConstKind::Unevaluated(..)) => {
88+
self.fields.add_const_equate_obligation(self.a_is_expected, a, b);
89+
Ok(a)
90+
}
91+
_ => self.fields.infcx.super_combine_consts(self, a, b),
92+
}
8393
}
8494

8595
fn binders<T>(

‎src/librustc_infer/infer/lub.rs‎

Lines changed: 11 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -79,7 +79,17 @@ impl TypeRelation<'tcx> for Lub<'combine, 'infcx, 'tcx> {
7979
a: &'tcx ty::Const<'tcx>,
8080
b: &'tcx ty::Const<'tcx>,
8181
) -> RelateResult<'tcx, &'tcx ty::Const<'tcx>> {
82-
self.fields.infcx.super_combine_consts(self, a, b)
82+
match (a.val, b.val) {
83+
(ty::ConstKind::Unevaluated(..), _) => {
84+
self.fields.add_const_equate_obligation(self.a_is_expected, a, b);
85+
Ok(b)
86+
}
87+
(_, ty::ConstKind::Unevaluated(..)) => {
88+
self.fields.add_const_equate_obligation(self.a_is_expected, a, b);
89+
Ok(a)
90+
}
91+
_ => self.fields.infcx.super_combine_consts(self, a, b),
92+
}
8393
}
8494

8595
fn binders<T>(

‎src/librustc_infer/infer/mod.rs‎

Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1490,6 +1490,17 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
14901490
self.report_and_explain_type_error(trace, &err)
14911491
}
14921492

1493+
pub fn report_mismatched_consts(
1494+
&self,
1495+
cause: &ObligationCause<'tcx>,
1496+
expected: &'tcx ty::Const<'tcx>,
1497+
actual: &'tcx ty::Const<'tcx>,
1498+
err: TypeError<'tcx>,
1499+
) -> DiagnosticBuilder<'tcx> {
1500+
let trace = TypeTrace::consts(cause, true, expected, actual);
1501+
self.report_and_explain_type_error(trace, &err)
1502+
}
1503+
14931504
pub fn replace_bound_vars_with_fresh_vars<T>(
14941505
&self,
14951506
span: Span,
@@ -1777,6 +1788,15 @@ impl<'tcx> TypeTrace<'tcx> {
17771788
TypeTrace { cause: cause.clone(), values: Types(ExpectedFound::new(a_is_expected, a, b)) }
17781789
}
17791790

1791+
pub fn consts(
1792+
cause: &ObligationCause<'tcx>,
1793+
a_is_expected: bool,
1794+
a: &'tcx ty::Const<'tcx>,
1795+
b: &'tcx ty::Const<'tcx>,
1796+
) -> TypeTrace<'tcx> {
1797+
TypeTrace { cause: cause.clone(), values: Consts(ExpectedFound::new(a_is_expected, a, b)) }
1798+
}
1799+
17801800
pub fn dummy(tcx: TyCtxt<'tcx>) -> TypeTrace<'tcx> {
17811801
TypeTrace {
17821802
cause: ObligationCause::dummy(),

‎src/librustc_infer/infer/nll_relate/mod.rs‎

Lines changed: 13 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -77,6 +77,8 @@ pub trait TypeRelatingDelegate<'tcx> {
7777
/// delegate.
7878
fn push_outlives(&mut self, sup: ty::Region<'tcx>, sub: ty::Region<'tcx>);
7979

80+
fn const_equate(&mut self, a: &'tcx ty::Const<'tcx>, b: &'tcx ty::Const<'tcx>);
81+
8082
/// Creates a new universe index. Used when instantiating placeholders.
8183
fn create_next_universe(&mut self) -> ty::UniverseIndex;
8284

@@ -592,8 +594,16 @@ where
592594
b = self.infcx.shallow_resolve(b);
593595
}
594596

595-
match b.val {
596-
ty::ConstKind::Infer(InferConst::Var(_)) if D::forbid_inference_vars() => {
597+
match (a.val, b.val) {
598+
(ty::ConstKind::Unevaluated(..), _) => {
599+
self.delegate.const_equate(a, b);
600+
Ok(b)
601+
}
602+
(_, ty::ConstKind::Unevaluated(..)) => {
603+
self.delegate.const_equate(a, b);
604+
Ok(a)
605+
}
606+
(_, ty::ConstKind::Infer(InferConst::Var(_))) if D::forbid_inference_vars() => {
597607
// Forbid inference variables in the RHS.
598608
bug!("unexpected inference var {:?}", b)
599609
}
@@ -976,6 +986,7 @@ where
976986
}
977987
}
978988
}
989+
ty::ConstKind::Unevaluated(..) => Ok(a),
979990
_ => relate::super_relate_consts(self, a, a),
980991
}
981992
}

‎src/librustc_infer/infer/outlives/mod.rs‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -19,7 +19,8 @@ pub fn explicit_outlives_bounds<'tcx>(
1919
| ty::Predicate::ObjectSafe(..)
2020
| ty::Predicate::ClosureKind(..)
2121
| ty::Predicate::TypeOutlives(..)
22-
| ty::Predicate::ConstEvaluatable(..) => None,
22+
| ty::Predicate::ConstEvaluatable(..)
23+
| ty::Predicate::ConstEquate(..) => None,
2324
ty::Predicate::RegionOutlives(ref data) => data
2425
.no_bound_vars()
2526
.map(|ty::OutlivesPredicate(r_a, r_b)| OutlivesBound::RegionSubRegion(r_b, r_a)),

‎src/librustc_infer/infer/sub.rs‎

Lines changed: 11 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -155,7 +155,17 @@ impl TypeRelation<'tcx> for Sub<'combine, 'infcx, 'tcx> {
155155
a: &'tcx ty::Const<'tcx>,
156156
b: &'tcx ty::Const<'tcx>,
157157
) -> RelateResult<'tcx, &'tcx ty::Const<'tcx>> {
158-
self.fields.infcx.super_combine_consts(self, a, b)
158+
match (a.val, b.val) {
159+
(ty::ConstKind::Unevaluated(..), _) => {
160+
self.fields.add_const_equate_obligation(self.a_is_expected, a, b);
161+
Ok(b)
162+
}
163+
(_, ty::ConstKind::Unevaluated(..)) => {
164+
self.fields.add_const_equate_obligation(self.a_is_expected, a, b);
165+
Ok(a)
166+
}
167+
_ => self.fields.infcx.super_combine_consts(self, a, b),
168+
}
159169
}
160170

161171
fn binders<T>(

‎src/librustc_infer/traits/mod.rs‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@ pub mod util;
1010

1111
use rustc_hir as hir;
1212
use rustc_middle::ty::error::{ExpectedFound, TypeError};
13-
use rustc_middle::ty::{self, Ty};
13+
use rustc_middle::ty::{self, Const, Ty};
1414
use rustc_span::Span;
1515

1616
pub use self::FulfillmentErrorCode::*;
@@ -81,6 +81,7 @@ pub enum FulfillmentErrorCode<'tcx> {
8181
CodeSelectionError(SelectionError<'tcx>),
8282
CodeProjectionError(MismatchedProjectionTypes<'tcx>),
8383
CodeSubtypeError(ExpectedFound<Ty<'tcx>>, TypeError<'tcx>), // always comes from a SubtypePredicate
84+
CodeConstEquateError(ExpectedFound<&'tcx Const<'tcx>>, TypeError<'tcx>),
8485
CodeAmbiguity,
8586
}
8687

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