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Rollup merge of #130514 - compiler-errors:unsafe-binders, r=oli-obk

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Implement MIR lowering for unsafe binders

This is the final bit of the unsafe binders puzzle. It implements MIR, CTFE, and codegen for unsafe binders, and enforces that (for now) they are `Copy`. Later on, I'll introduce a new trait that relaxes this requirement to being "is `Copy` or `ManuallyDrop<T>`" which more closely models how we treat union fields.

Namely, wrapping unsafe binders is now `Rvalue::WrapUnsafeBinder`, which acts much like an `Rvalue::Aggregate`. Unwrapping unsafe binders are implemented as a MIR projection `ProjectionElem::UnwrapUnsafeBinder`, which acts much like `ProjectionElem::Field`.

Tracking:
- https://github.com/rust-lang/rust/issues/130516
This commit is contained in:
Matthias Krüger 2025-02-01 16:41:03 +01:00 • committed by GitHub
commit bbb8733515
1 changed files with 7 additions and 1 deletions
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8
src/base.rs
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@ -925,6 +925,10 @@ fn codegen_stmt<'tcx>(
}
crate::discriminant::codegen_set_discriminant(fx, lval, variant_index);
}
Rvalue::WrapUnsafeBinder(ref operand, _to_ty) => {
let operand = codegen_operand(fx, operand);
lval.write_cvalue_transmute(fx, operand);
}
}
}
StatementKind::StorageLive(_)
@ -993,7 +997,9 @@ pub(crate) fn codegen_place<'tcx>(
cplace = cplace.place_deref(fx);
}
PlaceElem::OpaqueCast(ty) => bug!("encountered OpaqueCast({ty}) in codegen"),
PlaceElem::Subtype(ty) => cplace = cplace.place_transmute_type(fx, fx.monomorphize(ty)),
PlaceElem::Subtype(ty) | PlaceElem::UnwrapUnsafeBinder(ty) => {
cplace = cplace.place_transmute_type(fx, fx.monomorphize(ty));
}
PlaceElem::Field(field, _ty) => {
cplace = cplace.place_field(fx, field);
}