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Add unwrap_unsafe_binder and wrap_unsafe_binder macro operators
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13 files changed

+135
-13
lines changed

13 files changed

+135
-13
lines changed

‎compiler/rustc_hir_typeck/src/expr.rs‎

Lines changed: 63 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1645,14 +1645,71 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
16451645

16461646
fn check_expr_unsafe_binder_cast(
16471647
&self,
1648-
_kind: hir::UnsafeBinderCastKind,
1648+
kind: hir::UnsafeBinderCastKind,
16491649
expr: &'tcx hir::Expr<'tcx>,
1650-
_hir_ty: Option<&'tcx hir::Ty<'tcx>>,
1651-
_expected: Expectation<'tcx>,
1650+
hir_ty: Option<&'tcx hir::Ty<'tcx>>,
1651+
expected: Expectation<'tcx>,
16521652
) -> Ty<'tcx> {
1653-
let guar =
1654-
self.dcx().struct_span_err(expr.span, "unsafe binders are not yet implemented").emit();
1655-
Ty::new_error(self.tcx, guar)
1653+
match kind {
1654+
hir::UnsafeBinderCastKind::Wrap => {
1655+
let ascribed_ty =
1656+
hir_ty.map(|hir_ty| self.lower_ty_saving_user_provided_ty(hir_ty));
1657+
let expected_ty = expected.only_has_type(self);
1658+
let binder_ty = match (ascribed_ty, expected_ty) {
1659+
(Some(ascribed_ty), Some(expected_ty)) => {
1660+
self.demand_eqtype(expr.span, expected_ty, ascribed_ty);
1661+
expected_ty
1662+
}
1663+
(Some(ty), None) | (None, Some(ty)) => ty,
1664+
(None, None) => self.next_ty_var(expr.span),
1665+
};
1666+
1667+
// Unwrap the binder eagerly if we can use it to guide inference on
1668+
// the inner expr. If not, then we'll error *after* type checking.
1669+
let hint_ty = if let ty::UnsafeBinder(binder) =
1670+
*self.try_structurally_resolve_type(expr.span, binder_ty).kind()
1671+
{
1672+
self.instantiate_binder_with_fresh_vars(
1673+
expr.span,
1674+
infer::BoundRegionConversionTime::HigherRankedType,
1675+
binder.into(),
1676+
)
1677+
} else {
1678+
self.next_ty_var(expr.span)
1679+
};
1680+
1681+
self.check_expr_has_type_or_error(expr, hint_ty, |_| {});
1682+
1683+
let binder_ty = self.structurally_resolve_type(expr.span, binder_ty);
1684+
match *binder_ty.kind() {
1685+
ty::UnsafeBinder(..) => {
1686+
// Ok
1687+
}
1688+
_ => todo!(),
1689+
}
1690+
1691+
binder_ty
1692+
}
1693+
hir::UnsafeBinderCastKind::Unwrap => {
1694+
let ascribed_ty =
1695+
hir_ty.map(|hir_ty| self.lower_ty_saving_user_provided_ty(hir_ty));
1696+
let hint_ty = ascribed_ty.unwrap_or_else(|| self.next_ty_var(expr.span));
1697+
// FIXME(unsafe_binders): coerce here if needed?
1698+
let binder_ty = self.check_expr_has_type_or_error(expr, hint_ty, |_| {});
1699+
1700+
// Unwrap the binder. This will be ambiguous if it's an infer var, and will error
1701+
// if it's not an unsafe binder.
1702+
let binder_ty = self.structurally_resolve_type(expr.span, binder_ty);
1703+
match *binder_ty.kind() {
1704+
ty::UnsafeBinder(binder) => self.instantiate_binder_with_fresh_vars(
1705+
expr.span,
1706+
infer::BoundRegionConversionTime::HigherRankedType,
1707+
binder.into(),
1708+
),
1709+
_ => todo!(),
1710+
}
1711+
}
1712+
}
16561713
}
16571714

16581715
fn check_expr_array(

‎compiler/rustc_middle/src/thir.rs‎

Lines changed: 11 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -16,7 +16,7 @@ use rustc_abi::{FieldIdx, Integer, Size, VariantIdx};
1616
use rustc_ast::{AsmMacro, InlineAsmOptions, InlineAsmTemplatePiece};
1717
use rustc_hir as hir;
1818
use rustc_hir::def_id::DefId;
19-
use rustc_hir::{BindingMode, ByRef, HirId, MatchSource, RangeEnd};
19+
use rustc_hir::{BindingMode, ByRef, HirId, MatchSource, RangeEnd, UnsafeBinderCastKind};
2020
use rustc_index::{IndexVec, newtype_index};
2121
use rustc_macros::{HashStable, TyDecodable, TyEncodable, TypeVisitable};
2222
use rustc_middle::middle::region;
@@ -489,6 +489,16 @@ pub enum ExprKind<'tcx> {
489489
user_ty: UserTy<'tcx>,
490490
user_ty_span: Span,
491491
},
492+
/// An unsafe binder cast on a place, e.g. `unwrap_unsafe_binder!(x)`.
493+
PlaceUnsafeBinderCast {
494+
kind: UnsafeBinderCastKind,
495+
source: ExprId,
496+
},
497+
/// An unsafe binder cast on a value, e.g. `wrap_unsafe_binder!(1; unsafe<> i32)`.
498+
ValueUnsafeBinderCast {
499+
kind: UnsafeBinderCastKind,
500+
source: ExprId,
501+
},
492502
/// A closure definition.
493503
Closure(Box<ClosureExpr<'tcx>>),
494504
/// A literal.

‎compiler/rustc_middle/src/thir/visit.rs‎

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -136,6 +136,9 @@ pub fn walk_expr<'thir, 'tcx: 'thir, V: Visitor<'thir, 'tcx>>(
136136
| ValueTypeAscription { source, user_ty: _, user_ty_span: _ } => {
137137
visitor.visit_expr(&visitor.thir()[source])
138138
}
139+
PlaceUnsafeBinderCast { source, kind: _ } | ValueUnsafeBinderCast { source, kind: _ } => {
140+
visitor.visit_expr(&visitor.thir()[source])
141+
}
139142
Closure(box ClosureExpr {
140143
closure_id: _,
141144
args: _,

‎compiler/rustc_mir_build/src/build/expr/as_place.rs‎

Lines changed: 16 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -523,6 +523,22 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
523523
block.and(PlaceBuilder::from(temp))
524524
}
525525

526+
ExprKind::PlaceUnsafeBinderCast { source, kind: _ } => {
527+
let place_builder = unpack!(
528+
block = this.expr_as_place(block, source, mutability, fake_borrow_temps,)
529+
);
530+
// TODO: stick on a projection elem
531+
block.and(place_builder)
532+
}
533+
ExprKind::ValueUnsafeBinderCast { source, kind: _ } => {
534+
let source_expr = &this.thir[source];
535+
let temp = unpack!(
536+
block = this.as_temp(block, source_expr.temp_lifetime, source, mutability)
537+
);
538+
// TODO: stick on a projection elem
539+
block.and(PlaceBuilder::from(temp))
540+
}
541+
526542
ExprKind::Array { .. }
527543
| ExprKind::Tuple { .. }
528544
| ExprKind::Adt { .. }

‎compiler/rustc_mir_build/src/build/expr/as_rvalue.rs‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -532,7 +532,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
532532
| ExprKind::Become { .. }
533533
| ExprKind::InlineAsm { .. }
534534
| ExprKind::PlaceTypeAscription { .. }
535-
| ExprKind::ValueTypeAscription { .. } => {
535+
| ExprKind::ValueTypeAscription { .. }
536+
| ExprKind::PlaceUnsafeBinderCast { .. }
537+
| ExprKind::ValueUnsafeBinderCast { .. } => {
536538
// these do not have corresponding `Rvalue` variants,
537539
// so make an operand and then return that
538540
debug_assert!(!matches!(

‎compiler/rustc_mir_build/src/build/expr/category.rs‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -41,7 +41,9 @@ impl Category {
4141
| ExprKind::UpvarRef { .. }
4242
| ExprKind::VarRef { .. }
4343
| ExprKind::PlaceTypeAscription { .. }
44-
| ExprKind::ValueTypeAscription { .. } => Some(Category::Place),
44+
| ExprKind::ValueTypeAscription { .. }
45+
| ExprKind::PlaceUnsafeBinderCast { .. }
46+
| ExprKind::ValueUnsafeBinderCast { .. } => Some(Category::Place),
4547

4648
ExprKind::LogicalOp { .. }
4749
| ExprKind::Match { .. }

‎compiler/rustc_mir_build/src/build/expr/into.rs‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -548,7 +548,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
548548
ExprKind::VarRef { .. }
549549
| ExprKind::UpvarRef { .. }
550550
| ExprKind::PlaceTypeAscription { .. }
551-
| ExprKind::ValueTypeAscription { .. } => {
551+
| ExprKind::ValueTypeAscription { .. }
552+
| ExprKind::PlaceUnsafeBinderCast { .. }
553+
| ExprKind::ValueUnsafeBinderCast { .. } => {
552554
debug_assert!(Category::of(&expr.kind) == Some(Category::Place));
553555

554556
let place = unpack!(block = this.as_place(block, expr_id));

‎compiler/rustc_mir_build/src/check_unsafety.rs‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -440,6 +440,8 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
440440
| ExprKind::NeverToAny { .. }
441441
| ExprKind::PlaceTypeAscription { .. }
442442
| ExprKind::ValueTypeAscription { .. }
443+
| ExprKind::PlaceUnsafeBinderCast { .. }
444+
| ExprKind::ValueUnsafeBinderCast { .. }
443445
| ExprKind::PointerCoercion { .. }
444446
| ExprKind::Repeat { .. }
445447
| ExprKind::StaticRef { .. }

‎compiler/rustc_mir_build/src/thir/cx/expr.rs‎

Lines changed: 8 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -917,8 +917,14 @@ impl<'tcx> Cx<'tcx> {
917917
}
918918
}
919919

920-
hir::ExprKind::UnsafeBinderCast(_kind, _source, _ty) => {
921-
unreachable!("unsafe binders are not yet implemented")
920+
hir::ExprKind::UnsafeBinderCast(kind, source, _ty) => {
921+
// FIXME(unsafe_binders): Take into account the ascribed type, too.
922+
let mirrored = self.mirror_expr(source);
923+
if source.is_syntactic_place_expr() {
924+
ExprKind::PlaceUnsafeBinderCast { source: mirrored, kind }
925+
} else {
926+
ExprKind::ValueUnsafeBinderCast { source: mirrored, kind }
927+
}
922928
}
923929

924930
hir::ExprKind::DropTemps(source) => ExprKind::Use { source: self.mirror_expr(source) },

‎compiler/rustc_mir_build/src/thir/pattern/check_match.rs‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -326,7 +326,9 @@ impl<'p, 'tcx> MatchVisitor<'p, 'tcx> {
326326
| Use { source }
327327
| PointerCoercion { source, .. }
328328
| PlaceTypeAscription { source, .. }
329-
| ValueTypeAscription { source, .. } => {
329+
| ValueTypeAscription { source, .. }
330+
| ExprKind::PlaceUnsafeBinderCast { source, .. }
331+
| ExprKind::ValueUnsafeBinderCast { source, .. } => {
330332
self.is_known_valid_scrutinee(&self.thir()[*source])
331333
}
332334

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