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varkorvarkor
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Implement fold_const for BoundVarReplacer
1 parent fa394c2 commit cf1a719

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4 files changed

+81
-18
lines changed

4 files changed

+81
-18
lines changed

‎src/librustc/infer/canonical/substitute.rs‎

Lines changed: 8 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -70,6 +70,13 @@ where
7070
}
7171
};
7272

73-
tcx.replace_escaping_bound_vars(value, fld_r, fld_t).0
73+
let fld_c = |bound_ct: ty::BoundVar, _| {
74+
match var_values.var_values[bound_ct].unpack() {
75+
UnpackedKind::Const(ct) => ct,
76+
c => bug!("{:?} is a const but value is {:?}", bound_ct, c),
77+
}
78+
};
79+
80+
tcx.replace_escaping_bound_vars(value, fld_r, fld_t, fld_c).0
7481
}
7582
}

‎src/librustc/infer/higher_ranked/mod.rs‎

Lines changed: 13 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -4,10 +4,12 @@
44
use super::combine::CombineFields;
55
use super::{HigherRankedType, InferCtxt, PlaceholderMap};
66

7-
use crate::infer::CombinedSnapshot;
7+
use crate::infer::{CombinedSnapshot, ConstVariableOrigin};
88
use crate::ty::relate::{Relate, RelateResult, TypeRelation};
99
use crate::ty::{self, Binder, TypeFoldable};
1010

11+
use syntax_pos::DUMMY_SP;
12+
1113
impl<'a, 'gcx, 'tcx> CombineFields<'a, 'gcx, 'tcx> {
1214
pub fn higher_ranked_sub<T>(
1315
&mut self,
@@ -99,7 +101,16 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
99101
}))
100102
};
101103

102-
let (result, map) = self.tcx.replace_bound_vars(binder, fld_r, fld_t);
104+
let fld_c = |_: ty::BoundVar, ty| {
105+
self.next_const_var_in_universe(
106+
ty,
107+
// FIXME(const_generics): do we want a placeholder const?
108+
ConstVariableOrigin::MiscVariable(DUMMY_SP),
109+
next_universe,
110+
)
111+
};
112+
113+
let (result, map) = self.tcx.replace_bound_vars(binder, fld_r, fld_t, fld_c);
103114

104115
debug!(
105116
"replace_bound_vars_with_placeholders(\

‎src/librustc/infer/mod.rs‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1476,7 +1476,8 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
14761476
{
14771477
let fld_r = |br| self.next_region_var(LateBoundRegion(span, br, lbrct));
14781478
let fld_t = |_| self.next_ty_var(TypeVariableOrigin::MiscVariable(span));
1479-
self.tcx.replace_bound_vars(value, fld_r, fld_t)
1479+
let fld_c = |_, ty| self.next_const_var(ty, ConstVariableOrigin::MiscVariable(span));
1480+
self.tcx.replace_bound_vars(value, fld_r, fld_t, fld_c)
14801481
}
14811482

14821483
/// See the [`region_constraints::verify_generic_bound`] method.

‎src/librustc/ty/fold.rs‎

Lines changed: 58 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -431,22 +431,26 @@ struct BoundVarReplacer<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
431431

432432
fld_r: &'a mut (dyn FnMut(ty::BoundRegion) -> ty::Region<'tcx> + 'a),
433433
fld_t: &'a mut (dyn FnMut(ty::BoundTy) -> Ty<'tcx> + 'a),
434+
fld_c: &'a mut (dyn FnMut(ty::BoundVar, Ty<'tcx>) -> &'tcx ty::LazyConst<'tcx> + 'a),
434435
}
435436

436437
impl<'a, 'gcx, 'tcx> BoundVarReplacer<'a, 'gcx, 'tcx> {
437-
fn new<F, G>(
438+
fn new<F, G, H>(
438439
tcx: TyCtxt<'a, 'gcx, 'tcx>,
439440
fld_r: &'a mut F,
440-
fld_t: &'a mut G
441+
fld_t: &'a mut G,
442+
fld_c: &'a mut H,
441443
) -> Self
442444
where F: FnMut(ty::BoundRegion) -> ty::Region<'tcx>,
443-
G: FnMut(ty::BoundTy) -> Ty<'tcx>
445+
G: FnMut(ty::BoundTy) -> Ty<'tcx>,
446+
H: FnMut(ty::BoundVar, Ty<'tcx>) -> &'tcx ty::LazyConst<'tcx>,
444447
{
445448
BoundVarReplacer {
446449
tcx,
447450
current_index: ty::INNERMOST,
448451
fld_r,
449452
fld_t,
453+
fld_c,
450454
}
451455
}
452456
}
@@ -508,7 +512,29 @@ impl<'a, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for BoundVarReplacer<'a, 'gcx, 'tcx>
508512
}
509513

510514
fn fold_const(&mut self, ct: &'tcx ty::LazyConst<'tcx>) -> &'tcx ty::LazyConst<'tcx> {
511-
ct // FIXME(const_generics)
515+
if let ty::LazyConst::Evaluated(ty::Const {
516+
val: ConstValue::Infer(ty::InferConst::Canonical(debruijn, bound_const)),
517+
ty,
518+
}) = *ct {
519+
if debruijn == self.current_index {
520+
let fld_c = &mut self.fld_c;
521+
let ct = fld_c(bound_const, ty);
522+
ty::fold::shift_vars(
523+
self.tcx,
524+
&ct,
525+
self.current_index.as_u32()
526+
)
527+
} else {
528+
ct
529+
}
530+
} else {
531+
if !ct.has_vars_bound_at_or_above(self.current_index) {
532+
// Nothing more to substitute.
533+
ct
534+
} else {
535+
ct.super_fold_with(self)
536+
}
537+
}
512538
}
513539
}
514540

@@ -532,27 +558,34 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
532558
where F: FnMut(ty::BoundRegion) -> ty::Region<'tcx>,
533559
T: TypeFoldable<'tcx>
534560
{
535-
// identity for bound types
561+
// identity for bound types and consts
536562
let fld_t = |bound_ty| self.mk_ty(ty::Bound(ty::INNERMOST, bound_ty));
537-
self.replace_escaping_bound_vars(value.skip_binder(), fld_r, fld_t)
563+
let fld_c = |bound_ct, ty| {
564+
self.mk_const_infer(ty::InferConst::Canonical(ty::INNERMOST, bound_ct), ty)
565+
};
566+
self.replace_escaping_bound_vars(value.skip_binder(), fld_r, fld_t, fld_c)
538567
}
539568

540569
/// Replaces all escaping bound vars. The `fld_r` closure replaces escaping
541-
/// bound regions while the `fld_t` closure replaces escaping bound types.
542-
pub fn replace_escaping_bound_vars<T, F, G>(
570+
/// bound regions; the `fld_t` closure replaces escaping bound types and the `fld_c`
571+
/// closure replaces escaping bound consts.
572+
pub fn replace_escaping_bound_vars<T, F, G, H>(
543573
self,
544574
value: &T,
545575
mut fld_r: F,
546-
mut fld_t: G
576+
mut fld_t: G,
577+
mut fld_c: H,
547578
) -> (T, BTreeMap<ty::BoundRegion, ty::Region<'tcx>>)
548579
where F: FnMut(ty::BoundRegion) -> ty::Region<'tcx>,
549580
G: FnMut(ty::BoundTy) -> Ty<'tcx>,
550-
T: TypeFoldable<'tcx>
581+
H: FnMut(ty::BoundVar, Ty<'tcx>) -> &'tcx ty::LazyConst<'tcx>,
582+
T: TypeFoldable<'tcx>,
551583
{
552584
use rustc_data_structures::fx::FxHashMap;
553585

554586
let mut region_map = BTreeMap::new();
555587
let mut type_map = FxHashMap::default();
588+
let mut const_map = FxHashMap::default();
556589

557590
if !value.has_escaping_bound_vars() {
558591
(value.clone(), region_map)
@@ -565,7 +598,16 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
565598
*type_map.entry(bound_ty).or_insert_with(|| fld_t(bound_ty))
566599
};
567600

568-
let mut replacer = BoundVarReplacer::new(self, &mut real_fld_r, &mut real_fld_t);
601+
let mut real_fld_c = |bound_ct, ty| {
602+
*const_map.entry(bound_ct).or_insert_with(|| fld_c(bound_ct, ty))
603+
};
604+
605+
let mut replacer = BoundVarReplacer::new(
606+
self,
607+
&mut real_fld_r,
608+
&mut real_fld_t,
609+
&mut real_fld_c,
610+
);
569611
let result = value.fold_with(&mut replacer);
570612
(result, region_map)
571613
}
@@ -574,17 +616,19 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
574616
/// Replaces all types or regions bound by the given `Binder`. The `fld_r`
575617
/// closure replaces bound regions while the `fld_t` closure replaces bound
576618
/// types.
577-
pub fn replace_bound_vars<T, F, G>(
619+
pub fn replace_bound_vars<T, F, G, H>(
578620
self,
579621
value: &Binder<T>,
580622
fld_r: F,
581-
fld_t: G
623+
fld_t: G,
624+
fld_c: H,
582625
) -> (T, BTreeMap<ty::BoundRegion, ty::Region<'tcx>>)
583626
where F: FnMut(ty::BoundRegion) -> ty::Region<'tcx>,
584627
G: FnMut(ty::BoundTy) -> Ty<'tcx>,
628+
H: FnMut(ty::BoundVar, Ty<'tcx>) -> &'tcx ty::LazyConst<'tcx>,
585629
T: TypeFoldable<'tcx>
586630
{
587-
self.replace_escaping_bound_vars(value.skip_binder(), fld_r, fld_t)
631+
self.replace_escaping_bound_vars(value.skip_binder(), fld_r, fld_t, fld_c)
588632
}
589633

590634
/// Replaces any late-bound regions bound in `value` with

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