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Auto merge of #99730 - lcnr:bound-vars-anon, r=jackh726 

anonymize all bound vars, not just regions

fixes #98702

r? types
This commit is contained in:
bors 2022-07-29 21:38:36 +00:00
parent 3924dac7bb 1436fa9e90
commit 211637d080
10 changed files with 260 additions and 138 deletions
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30
compiler/rustc_infer/src/infer/canonical/substitute.rs
View File

@ -7,7 +7,7 @@
//! [c]: https://rust-lang.github.io/chalk/book/canonical_queries/canonicalization.html
use crate::infer::canonical::{Canonical, CanonicalVarValues};
use rustc_middle::ty::fold::TypeFoldable;
use rustc_middle::ty::fold::{FnMutDelegate, TypeFoldable};
use rustc_middle::ty::subst::GenericArgKind;
use rustc_middle::ty::{self, TyCtxt};
@ -71,21 +71,21 @@ where
if var_values.var_values.is_empty() {
value
} else {
let fld_r = |br: ty::BoundRegion| match var_values.var_values[br.var].unpack() {
GenericArgKind::Lifetime(l) => l,
r => bug!("{:?} is a region but value is {:?}", br, r),
let delegate = FnMutDelegate {
regions: |br: ty::BoundRegion| match var_values.var_values[br.var].unpack() {
GenericArgKind::Lifetime(l) => l,
r => bug!("{:?} is a region but value is {:?}", br, r),
},
types: |bound_ty: ty::BoundTy| match var_values.var_values[bound_ty.var].unpack() {
GenericArgKind::Type(ty) => ty,
r => bug!("{:?} is a type but value is {:?}", bound_ty, r),
},
consts: |bound_ct: ty::BoundVar, _| match var_values.var_values[bound_ct].unpack() {
GenericArgKind::Const(ct) => ct,
c => bug!("{:?} is a const but value is {:?}", bound_ct, c),
},
};
let fld_t = |bound_ty: ty::BoundTy| match var_values.var_values[bound_ty.var].unpack() {
GenericArgKind::Type(ty) => ty,
r => bug!("{:?} is a type but value is {:?}", bound_ty, r),
};
let fld_c = |bound_ct: ty::BoundVar, _| match var_values.var_values[bound_ct].unpack() {
GenericArgKind::Const(ct) => ct,
c => bug!("{:?} is a const but value is {:?}", bound_ct, c),
};
tcx.replace_escaping_bound_vars_uncached(value, fld_r, fld_t, fld_c)
tcx.replace_escaping_bound_vars_uncached(value, delegate)
}
}

45
compiler/rustc_infer/src/infer/higher_ranked/mod.rs
View File

@ -4,6 +4,7 @@
use super::combine::CombineFields;
use super::{HigherRankedType, InferCtxt};
use crate::infer::CombinedSnapshot;
use rustc_middle::ty::fold::FnMutDelegate;
use rustc_middle::ty::relate::{Relate, RelateResult, TypeRelation};
use rustc_middle::ty::{self, Binder, TypeFoldable};
@ -79,31 +80,31 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
let next_universe = self.create_next_universe();
let fld_r = |br: ty::BoundRegion| {
self.tcx.mk_region(ty::RePlaceholder(ty::PlaceholderRegion {
universe: next_universe,
name: br.kind,
}))
};
let fld_t = |bound_ty: ty::BoundTy| {
self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
universe: next_universe,
name: bound_ty.var,
}))
};
let fld_c = |bound_var: ty::BoundVar, ty| {
self.tcx.mk_const(ty::ConstS {
kind: ty::ConstKind::Placeholder(ty::PlaceholderConst {
let delegate = FnMutDelegate {
regions: |br: ty::BoundRegion| {
self.tcx.mk_region(ty::RePlaceholder(ty::PlaceholderRegion {
universe: next_universe,
name: ty::BoundConst { var: bound_var, ty },
}),
ty,
})
name: br.kind,
}))
},
types: |bound_ty: ty::BoundTy| {
self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
universe: next_universe,
name: bound_ty.var,
}))
},
consts: |bound_var: ty::BoundVar, ty| {
self.tcx.mk_const(ty::ConstS {
kind: ty::ConstKind::Placeholder(ty::PlaceholderConst {
universe: next_universe,
name: ty::BoundConst { var: bound_var, ty },
}),
ty,
})
},
};
let result = self.tcx.replace_bound_vars_uncached(binder, fld_r, fld_t, fld_c);
let result = self.tcx.replace_bound_vars_uncached(binder, delegate);
debug!(?next_universe, ?result);
result
}

75
compiler/rustc_infer/src/infer/mod.rs
View File

@ -23,6 +23,7 @@ use rustc_middle::mir::interpret::{ErrorHandled, EvalToValTreeResult};
use rustc_middle::traits::select;
use rustc_middle::ty::abstract_const::{AbstractConst, FailureKind};
use rustc_middle::ty::error::{ExpectedFound, TypeError};
use rustc_middle::ty::fold::BoundVarReplacerDelegate;
use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
use rustc_middle::ty::relate::RelateResult;
use rustc_middle::ty::subst::{GenericArg, GenericArgKind, InternalSubsts, SubstsRef};
@ -1564,32 +1565,56 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
return inner;
}
let mut region_map = FxHashMap::default();
let fld_r = |br: ty::BoundRegion| {
*region_map
.entry(br)
.or_insert_with(|| self.next_region_var(LateBoundRegion(span, br.kind, lbrct)))
};
struct ToFreshVars<'a, 'tcx> {
infcx: &'a InferCtxt<'a, 'tcx>,
span: Span,
lbrct: LateBoundRegionConversionTime,
map: FxHashMap<ty::BoundVar, ty::GenericArg<'tcx>>,
}
let mut ty_map = FxHashMap::default();
let fld_t = |bt: ty::BoundTy| {
*ty_map.entry(bt).or_insert_with(|| {
self.next_ty_var(TypeVariableOrigin {
kind: TypeVariableOriginKind::MiscVariable,
span,
})
})
};
let mut ct_map = FxHashMap::default();
let fld_c = |bc: ty::BoundVar, ty| {
*ct_map.entry(bc).or_insert_with(|| {
self.next_const_var(
ty,
ConstVariableOrigin { kind: ConstVariableOriginKind::MiscVariable, span },
)
})
};
self.tcx.replace_bound_vars_uncached(value, fld_r, fld_t, fld_c)
impl<'tcx> BoundVarReplacerDelegate<'tcx> for ToFreshVars<'_, 'tcx> {
fn replace_region(&mut self, br: ty::BoundRegion) -> ty::Region<'tcx> {
self.map
.entry(br.var)
.or_insert_with(|| {
self.infcx
.next_region_var(LateBoundRegion(self.span, br.kind, self.lbrct))
.into()
})
.expect_region()
}
fn replace_ty(&mut self, bt: ty::BoundTy) -> Ty<'tcx> {
self.map
.entry(bt.var)
.or_insert_with(|| {
self.infcx
.next_ty_var(TypeVariableOrigin {
kind: TypeVariableOriginKind::MiscVariable,
span: self.span,
})
.into()
})
.expect_ty()
}
fn replace_const(&mut self, bv: ty::BoundVar, ty: Ty<'tcx>) -> ty::Const<'tcx> {
self.map
.entry(bv)
.or_insert_with(|| {
self.infcx
.next_const_var(
ty,
ConstVariableOrigin {
kind: ConstVariableOriginKind::MiscVariable,
span: self.span,
},
)
.into()
})
.expect_const()
}
}
let delegate = ToFreshVars { infcx: self, span, lbrct, map: Default::default() };
self.tcx.replace_bound_vars_uncached(value, delegate)
}
/// See the [`region_constraints::RegionConstraintCollector::verify_generic_bound`] method.

4
compiler/rustc_infer/src/traits/util.rs
View File

@ -11,7 +11,7 @@ pub fn anonymize_predicate<'tcx>(
tcx: TyCtxt<'tcx>,
pred: ty::Predicate<'tcx>,
) -> ty::Predicate<'tcx> {
let new = tcx.anonymize_late_bound_regions(pred.kind());
let new = tcx.anonymize_bound_vars(pred.kind());
tcx.reuse_or_mk_predicate(pred, new)
}
@ -334,7 +334,7 @@ pub fn transitive_bounds_that_define_assoc_type<'tcx>(
std::iter::from_fn(move || {
while let Some(trait_ref) = stack.pop() {
let anon_trait_ref = tcx.anonymize_late_bound_regions(trait_ref);
let anon_trait_ref = tcx.anonymize_bound_vars(trait_ref);
if visited.insert(anon_trait_ref) {
let super_predicates = tcx.super_predicates_that_define_assoc_type((
trait_ref.def_id(),

2
compiler/rustc_middle/src/ty/erase_regions.rs
View File

@ -49,7 +49,7 @@ impl<'tcx> TypeFolder<'tcx> for RegionEraserVisitor<'tcx> {
where
T: TypeFoldable<'tcx>,
{
let u = self.tcx.anonymize_late_bound_regions(t);
let u = self.tcx.anonymize_bound_vars(t);
u.super_fold_with(self)
}

193
compiler/rustc_middle/src/ty/fold.rs
View File

@ -44,7 +44,8 @@
//! - u.fold_with(folder)
//! ```
use crate::mir;
use crate::ty::{self, Binder, Ty, TyCtxt, TypeVisitable};
use crate::ty::{self, Binder, BoundTy, Ty, TyCtxt, TypeVisitable};
use rustc_data_structures::fx::FxIndexMap;
use rustc_hir::def_id::DefId;
use std::collections::BTreeMap;
@ -370,31 +371,55 @@ impl<'a, 'tcx> TypeFolder<'tcx> for RegionFolder<'a, 'tcx> {
///////////////////////////////////////////////////////////////////////////
// Bound vars replacer
pub trait BoundVarReplacerDelegate<'tcx> {
fn replace_region(&mut self, br: ty::BoundRegion) -> ty::Region<'tcx>;
fn replace_ty(&mut self, bt: ty::BoundTy) -> Ty<'tcx>;
fn replace_const(&mut self, bv: ty::BoundVar, ty: Ty<'tcx>) -> ty::Const<'tcx>;
}
pub struct FnMutDelegate<R, T, C> {
pub regions: R,
pub types: T,
pub consts: C,
}
impl<'tcx, R, T, C> BoundVarReplacerDelegate<'tcx> for FnMutDelegate<R, T, C>
where
R: FnMut(ty::BoundRegion) -> ty::Region<'tcx>,
T: FnMut(ty::BoundTy) -> Ty<'tcx>,
C: FnMut(ty::BoundVar, Ty<'tcx>) -> ty::Const<'tcx>,
{
fn replace_region(&mut self, br: ty::BoundRegion) -> ty::Region<'tcx> {
(self.regions)(br)
}
fn replace_ty(&mut self, bt: ty::BoundTy) -> Ty<'tcx> {
(self.types)(bt)
}
fn replace_const(&mut self, bv: ty::BoundVar, ty: Ty<'tcx>) -> ty::Const<'tcx> {
(self.consts)(bv, ty)
}
}
/// Replaces the escaping bound vars (late bound regions or bound types) in a type.
struct BoundVarReplacer<'a, 'tcx> {
struct BoundVarReplacer<'tcx, D> {
tcx: TyCtxt<'tcx>,
/// As with `RegionFolder`, represents the index of a binder *just outside*
/// the ones we have visited.
current_index: ty::DebruijnIndex,
fld_r: &'a mut (dyn FnMut(ty::BoundRegion) -> ty::Region<'tcx> + 'a),
fld_t: &'a mut (dyn FnMut(ty::BoundTy) -> Ty<'tcx> + 'a),
fld_c: &'a mut (dyn FnMut(ty::BoundVar, Ty<'tcx>) -> ty::Const<'tcx> + 'a),
delegate: D,
}
impl<'a, 'tcx> BoundVarReplacer<'a, 'tcx> {
fn new(
tcx: TyCtxt<'tcx>,
fld_r: &'a mut (dyn FnMut(ty::BoundRegion) -> ty::Region<'tcx> + 'a),
fld_t: &'a mut (dyn FnMut(ty::BoundTy) -> Ty<'tcx> + 'a),
fld_c: &'a mut (dyn FnMut(ty::BoundVar, Ty<'tcx>) -> ty::Const<'tcx> + 'a),
) -> Self {
BoundVarReplacer { tcx, current_index: ty::INNERMOST, fld_r, fld_t, fld_c }
impl<'tcx, D: BoundVarReplacerDelegate<'tcx>> BoundVarReplacer<'tcx, D> {
fn new(tcx: TyCtxt<'tcx>, delegate: D) -> Self {
BoundVarReplacer { tcx, current_index: ty::INNERMOST, delegate }
}
}
impl<'a, 'tcx> TypeFolder<'tcx> for BoundVarReplacer<'a, 'tcx> {
impl<'tcx, D> TypeFolder<'tcx> for BoundVarReplacer<'tcx, D>
where
D: BoundVarReplacerDelegate<'tcx>,
{
fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
self.tcx
}
@ -412,7 +437,7 @@ impl<'a, 'tcx> TypeFolder<'tcx> for BoundVarReplacer<'a, 'tcx> {
fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
match *t.kind() {
ty::Bound(debruijn, bound_ty) if debruijn == self.current_index => {
let ty = (self.fld_t)(bound_ty);
let ty = self.delegate.replace_ty(bound_ty);
ty::fold::shift_vars(self.tcx, ty, self.current_index.as_u32())
}
_ if t.has_vars_bound_at_or_above(self.current_index) => t.super_fold_with(self),
@ -423,14 +448,14 @@ impl<'a, 'tcx> TypeFolder<'tcx> for BoundVarReplacer<'a, 'tcx> {
fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
match *r {
ty::ReLateBound(debruijn, br) if debruijn == self.current_index => {
let region = (self.fld_r)(br);
let region = self.delegate.replace_region(br);
if let ty::ReLateBound(debruijn1, br) = *region {
// If the callback returns a late-bound region,
// that region should always use the INNERMOST
// debruijn index. Then we adjust it to the
// correct depth.
assert_eq!(debruijn1, ty::INNERMOST);
self.tcx.mk_region(ty::ReLateBound(debruijn, br))
self.tcx.reuse_or_mk_region(region, ty::ReLateBound(debruijn, br))
} else {
region
}
@ -442,7 +467,7 @@ impl<'a, 'tcx> TypeFolder<'tcx> for BoundVarReplacer<'a, 'tcx> {
fn fold_const(&mut self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
match ct.kind() {
ty::ConstKind::Bound(debruijn, bound_const) if debruijn == self.current_index => {
let ct = (self.fld_c)(bound_const, ct.ty());
let ct = self.delegate.replace_const(bound_const, ct.ty());
ty::fold::shift_vars(self.tcx, ct, self.current_index.as_u32())
}
_ => ct.super_fold_with(self),
@ -486,19 +511,22 @@ impl<'tcx> TyCtxt<'tcx> {
pub fn replace_late_bound_regions_uncached<T, F>(
self,
value: Binder<'tcx, T>,
mut fld_r: F,
replace_regions: F,
) -> T
where
F: FnMut(ty::BoundRegion) -> ty::Region<'tcx>,
T: TypeFoldable<'tcx>,
{
let mut fld_t = |b| bug!("unexpected bound ty in binder: {b:?}");
let mut fld_c = |b, ty| bug!("unexpected bound ct in binder: {b:?} {ty}");
let value = value.skip_binder();
if !value.has_escaping_bound_vars() {
value
} else {
let mut replacer = BoundVarReplacer::new(self, &mut fld_r, &mut fld_t, &mut fld_c);
let delegate = FnMutDelegate {
regions: replace_regions,
types: |b| bug!("unexpected bound ty in binder: {b:?}"),
consts: |b, ty| bug!("unexpected bound ct in binder: {b:?} {ty}"),
};
let mut replacer = BoundVarReplacer::new(self, delegate);
value.fold_with(&mut replacer)
}
}
@ -506,23 +534,15 @@ impl<'tcx> TyCtxt<'tcx> {
/// Replaces all escaping bound vars. The `fld_r` closure replaces escaping
/// bound regions; the `fld_t` closure replaces escaping bound types and the `fld_c`
/// closure replaces escaping bound consts.
pub fn replace_escaping_bound_vars_uncached<T, F, G, H>(
pub fn replace_escaping_bound_vars_uncached<T: TypeFoldable<'tcx>>(
self,
value: T,
mut fld_r: F,
mut fld_t: G,
mut fld_c: H,
) -> T
where
F: FnMut(ty::BoundRegion) -> ty::Region<'tcx>,
G: FnMut(ty::BoundTy) -> Ty<'tcx>,
H: FnMut(ty::BoundVar, Ty<'tcx>) -> ty::Const<'tcx>,
T: TypeFoldable<'tcx>,
{
delegate: impl BoundVarReplacerDelegate<'tcx>,
) -> T {
if !value.has_escaping_bound_vars() {
value
} else {
let mut replacer = BoundVarReplacer::new(self, &mut fld_r, &mut fld_t, &mut fld_c);
let mut replacer = BoundVarReplacer::new(self, delegate);
value.fold_with(&mut replacer)
}
}
@ -530,20 +550,12 @@ impl<'tcx> TyCtxt<'tcx> {
/// Replaces all types or regions bound by the given `Binder`. The `fld_r`
/// closure replaces bound regions, the `fld_t` closure replaces bound
/// types, and `fld_c` replaces bound constants.
pub fn replace_bound_vars_uncached<T, F, G, H>(
pub fn replace_bound_vars_uncached<T: TypeFoldable<'tcx>>(
self,
value: Binder<'tcx, T>,
fld_r: F,
fld_t: G,
fld_c: H,
) -> T
where
F: FnMut(ty::BoundRegion) -> ty::Region<'tcx>,
G: FnMut(ty::BoundTy) -> Ty<'tcx>,
H: FnMut(ty::BoundVar, Ty<'tcx>) -> ty::Const<'tcx>,
T: TypeFoldable<'tcx>,
{
self.replace_escaping_bound_vars_uncached(value.skip_binder(), fld_r, fld_t, fld_c)
delegate: impl BoundVarReplacerDelegate<'tcx>,
) -> T {
self.replace_escaping_bound_vars_uncached(value.skip_binder(), delegate)
}
/// Replaces any late-bound regions bound in `value` with
@ -568,34 +580,28 @@ impl<'tcx> TyCtxt<'tcx> {
where
T: TypeFoldable<'tcx>,
{
let shift_bv = |bv: ty::BoundVar| ty::BoundVar::from_usize(bv.as_usize() + bound_vars);
self.replace_escaping_bound_vars_uncached(
value,
|r| {
self.mk_region(ty::ReLateBound(
ty::INNERMOST,
ty::BoundRegion {
var: ty::BoundVar::from_usize(r.var.as_usize() + bound_vars),
kind: r.kind,
},
))
},
|t| {
self.mk_ty(ty::Bound(
ty::INNERMOST,
ty::BoundTy {
var: ty::BoundVar::from_usize(t.var.as_usize() + bound_vars),
kind: t.kind,
},
))
},
|c, ty| {
self.mk_const(ty::ConstS {
kind: ty::ConstKind::Bound(
FnMutDelegate {
regions: |r: ty::BoundRegion| {
self.mk_region(ty::ReLateBound(
ty::INNERMOST,
ty::BoundVar::from_usize(c.as_usize() + bound_vars),
),
ty,
})
ty::BoundRegion { var: shift_bv(r.var), kind: r.kind },
))
},
types: |t: ty::BoundTy| {
self.mk_ty(ty::Bound(
ty::INNERMOST,
ty::BoundTy { var: shift_bv(t.var), kind: t.kind },
))
},
consts: |c, ty: Ty<'tcx>| {
self.mk_const(ty::ConstS {
kind: ty::ConstKind::Bound(ty::INNERMOST, shift_bv(c)),
ty,
})
},
},
)
}
@ -638,6 +644,51 @@ impl<'tcx> TyCtxt<'tcx> {
);
Binder::bind_with_vars(inner, bound_vars)
}
/// Anonymize all bound variables in `value`, this is mostly used to improve caching.
pub fn anonymize_bound_vars<T>(self, value: Binder<'tcx, T>) -> Binder<'tcx, T>
where
T: TypeFoldable<'tcx>,
{
struct Anonymize<'a, 'tcx> {
tcx: TyCtxt<'tcx>,
map: &'a mut FxIndexMap<ty::BoundVar, ty::BoundVariableKind>,
}
impl<'tcx> BoundVarReplacerDelegate<'tcx> for Anonymize<'_, 'tcx> {
fn replace_region(&mut self, br: ty::BoundRegion) -> ty::Region<'tcx> {
let entry = self.map.entry(br.var);
let index = entry.index();
let var = ty::BoundVar::from_usize(index);
let kind = entry
.or_insert_with(|| ty::BoundVariableKind::Region(ty::BrAnon(index as u32)))
.expect_region();
let br = ty::BoundRegion { var, kind };
self.tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br))
}
fn replace_ty(&mut self, bt: ty::BoundTy) -> Ty<'tcx> {
let entry = self.map.entry(bt.var);
let index = entry.index();
let var = ty::BoundVar::from_usize(index);
let kind = entry
.or_insert_with(|| ty::BoundVariableKind::Ty(ty::BoundTyKind::Anon))
.expect_ty();
self.tcx.mk_ty(ty::Bound(ty::INNERMOST, BoundTy { var, kind }))
}
fn replace_const(&mut self, bv: ty::BoundVar, ty: Ty<'tcx>) -> ty::Const<'tcx> {
let entry = self.map.entry(bv);
let index = entry.index();
let var = ty::BoundVar::from_usize(index);
let () = entry.or_insert_with(|| ty::BoundVariableKind::Const).expect_const();
self.tcx.mk_const(ty::ConstS { ty, kind: ty::ConstKind::Bound(ty::INNERMOST, var) })
}
}
let mut map = Default::default();
let delegate = Anonymize { tcx: self, map: &mut map };
let inner = self.replace_escaping_bound_vars_uncached(value.skip_binder(), delegate);
let bound_vars = self.mk_bound_variable_kinds(map.into_values());
Binder::bind_with_vars(inner, bound_vars)
}
}
///////////////////////////////////////////////////////////////////////////

23
compiler/rustc_middle/src/ty/sty.rs
View File

@ -976,6 +976,29 @@ pub enum BoundVariableKind {
Const,
}
impl BoundVariableKind {
pub fn expect_region(self) -> BoundRegionKind {
match self {
BoundVariableKind::Region(lt) => lt,
_ => bug!("expected a region, but found another kind"),
}
}
pub fn expect_ty(self) -> BoundTyKind {
match self {
BoundVariableKind::Ty(ty) => ty,
_ => bug!("expected a type, but found another kind"),
}
}
pub fn expect_const(self) {
match self {
BoundVariableKind::Const => (),
_ => bug!("expected a const, but found another kind"),
}
}
}
/// Binder is a binder for higher-ranked lifetimes or types. It is part of the
/// compiler's representation for things like `for<'a> Fn(&'a isize)`
/// (which would be represented by the type `PolyTraitRef ==

8
compiler/rustc_middle/src/ty/subst.rs
View File

@ -164,6 +164,14 @@ impl<'tcx> GenericArg<'tcx> {
}
}
/// Unpack the `GenericArg` as a region when it is known certainly to be a region.
pub fn expect_region(self) -> ty::Region<'tcx> {
match self.unpack() {
GenericArgKind::Lifetime(lt) => lt,
_ => bug!("expected a region, but found another kind"),
}
}
/// Unpack the `GenericArg` as a type when it is known certainly to be a type.
/// This is true in cases where `Substs` is used in places where the kinds are known
/// to be limited (e.g. in tuples, where the only parameters are type parameters).

4
compiler/rustc_typeck/src/check/dropck.rs
View File

@ -318,8 +318,8 @@ impl<'tcx> TypeRelation<'tcx> for SimpleEqRelation<'tcx> {
// Anonymizing the LBRs is necessary to solve (Issue #59497).
// After we do so, it should be totally fine to skip the binders.
let anon_a = self.tcx.anonymize_late_bound_regions(a);
let anon_b = self.tcx.anonymize_late_bound_regions(b);
let anon_a = self.tcx.anonymize_bound_vars(a);
let anon_b = self.tcx.anonymize_bound_vars(b);
self.relate(anon_a.skip_binder(), anon_b.skip_binder())?;
Ok(a)

14
src/test/ui/generic-associated-types/anonymize-bound-vars.rs Normal file
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@ -0,0 +1,14 @@
// check-pass
//
// regression test for #98702
#![feature(generic_associated_types)]
trait Foo {
type Assoc<T>;
}
impl Foo for () {
type Assoc<T> = [T; 2*2];
}
fn main() {}