bjoernager/rust
bjoernager/rust
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Remove BackendRepr::Uninhabited, replaced with an uninhabited: bool field in LayoutData.

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Also update comments that refered to BackendRepr::Uninhabited.
This commit is contained in:
Zachary S 2025-01-25 20:15:24 -06:00
parent 28b83ee596
commit 7ba3d7b54e
26 changed files with 93 additions and 113 deletions
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2
compiler/rustc_const_eval/src/interpret/operand.rs
View file

@ -385,7 +385,7 @@ impl<'tcx, Prov: Provenance> ImmTy<'tcx, Prov> {
(Immediate::Uninit, _) => Immediate::Uninit,
// If the field is uninhabited, we can forget the data (can happen in ConstProp).
// `enum S { A(!), B, C }` is an example of an enum with Scalar layout that
// has an `Uninhabited` variant, which means this case is possible.
// has an uninhabited variant, which means this case is possible.
_ if layout.is_uninhabited() => Immediate::Uninit,
// the field contains no information, can be left uninit
// (Scalar/ScalarPair can contain even aligned ZST, not just 1-ZST)

8
compiler/rustc_const_eval/src/interpret/validity.rs
View file

@ -1274,11 +1274,11 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValueVisitor<'tcx, M> for ValidityVisitor<'rt,
// FIXME: We could avoid some redundant checks here. For newtypes wrapping
// scalars, we do the same check on every "level" (e.g., first we check
// MyNewtype and then the scalar in there).
if val.layout.is_uninhabited() {
let ty = val.layout.ty;
throw_validation_failure!(self.path, UninhabitedVal { ty });
}
match val.layout.backend_repr {
BackendRepr::Uninhabited => {
let ty = val.layout.ty;
throw_validation_failure!(self.path, UninhabitedVal { ty });
}
BackendRepr::Scalar(scalar_layout) => {
if !scalar_layout.is_uninit_valid() {
// There is something to check here.

16
compiler/rustc_const_eval/src/util/check_validity_requirement.rs
View file

@ -111,13 +111,15 @@ fn check_validity_requirement_lax<'tcx>(
};
// Check the ABI.
let valid = match this.backend_repr {
BackendRepr::Uninhabited => false, // definitely UB
BackendRepr::Scalar(s) => scalar_allows_raw_init(s),
BackendRepr::ScalarPair(s1, s2) => scalar_allows_raw_init(s1) && scalar_allows_raw_init(s2),
BackendRepr::Vector { element: s, count } => count == 0 || scalar_allows_raw_init(s),
BackendRepr::Memory { .. } => true, // Fields are checked below.
};
let valid = !this.is_uninhabited() // definitely UB if uninhabited
&& match this.backend_repr {
BackendRepr::Scalar(s) => scalar_allows_raw_init(s),
BackendRepr::ScalarPair(s1, s2) => {
scalar_allows_raw_init(s1) && scalar_allows_raw_init(s2)
}
BackendRepr::Vector { element: s, count } => count == 0 || scalar_allows_raw_init(s),
BackendRepr::Memory { .. } => true, // Fields are checked below.
};
if !valid {
// This is definitely not okay.
return Ok(false);