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BoundVarReplacer: trait object instead of 3 fns

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This commit is contained in:
lcnr 2022-07-25 19:27:52 +02:00
parent 05e678ccca
commit fd59d058ec
5 changed files with 164 additions and 128 deletions
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134
compiler/rustc_middle/src/ty/fold.rs
View file

@ -370,6 +370,34 @@ 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> {
tcx: TyCtxt<'tcx>,
@ -378,19 +406,12 @@ struct BoundVarReplacer<'a, 'tcx> {
/// 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: &'a mut dyn BoundVarReplacerDelegate<'tcx>,
}
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 }
fn new(tcx: TyCtxt<'tcx>, delegate: &'a mut dyn BoundVarReplacerDelegate<'tcx>) -> Self {
BoundVarReplacer { tcx, current_index: ty::INNERMOST, delegate }
}
}
@ -412,7 +433,7 @@ 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),
@ -423,7 +444,7 @@ 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
@ -442,7 +463,7 @@ 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 +507,22 @@ 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 mut 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, &mut delegate);
value.fold_with(&mut replacer)
}
}
@ -506,23 +530,15 @@ 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>,
{
mut 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, &mut delegate);
value.fold_with(&mut replacer)
}
}
@ -530,20 +546,12 @@ 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 +576,28 @@ 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,
})
},
},
)
}

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).