diff options
Diffstat (limited to 'compiler/rustc_const_eval/src')
4 files changed, 18 insertions, 17 deletions
diff --git a/compiler/rustc_const_eval/src/interpret/discriminant.rs b/compiler/rustc_const_eval/src/interpret/discriminant.rs index 6faac1582ab..2f0b1cb6d1e 100644 --- a/compiler/rustc_const_eval/src/interpret/discriminant.rs +++ b/compiler/rustc_const_eval/src/interpret/discriminant.rs @@ -44,7 +44,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { } } - /// Read discriminant, return the runtime value as well as the variant index. + /// Read discriminant, return the variant index. /// Can also legally be called on non-enums (e.g. through the discriminant_value intrinsic)! /// /// Will never return an uninhabited variant. @@ -65,21 +65,17 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { // We use "tag" to refer to how the discriminant is encoded in memory, which can be either // straight-forward (`TagEncoding::Direct`) or with a niche (`TagEncoding::Niche`). let (tag_scalar_layout, tag_encoding, tag_field) = match op.layout().variants { + Variants::Empty => { + throw_ub!(UninhabitedEnumVariantRead(None)); + } Variants::Single { index } => { - // Do some extra checks on enums. - if ty.is_enum() { - // Hilariously, `Single` is used even for 0-variant enums. - // (See https://github.com/rust-lang/rust/issues/89765). - if ty.ty_adt_def().unwrap().variants().is_empty() { - throw_ub!(UninhabitedEnumVariantRead(index)) - } + if op.layout().is_uninhabited() { // For consistency with `write_discriminant`, and to make sure that // `project_downcast` cannot fail due to strange layouts, we declare immediate UB - // for uninhabited variants. - if op.layout().for_variant(self, index).is_uninhabited() { - throw_ub!(UninhabitedEnumVariantRead(index)) - } + // for uninhabited enums. + throw_ub!(UninhabitedEnumVariantRead(Some(index))); } + // Since the type is inhabited, there must be an index. return interp_ok(index); } Variants::Multiple { tag, ref tag_encoding, tag_field, .. } => { @@ -199,11 +195,13 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { // `uninhabited_enum_branching` MIR pass. It also ensures consistency with // `write_discriminant`. if op.layout().for_variant(self, index).is_uninhabited() { - throw_ub!(UninhabitedEnumVariantRead(index)) + throw_ub!(UninhabitedEnumVariantRead(Some(index))) } interp_ok(index) } + /// Read discriminant, return the user-visible discriminant. + /// Can also legally be called on non-enums (e.g. through the discriminant_value intrinsic)! pub fn discriminant_for_variant( &self, ty: Ty<'tcx>, @@ -243,6 +241,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { } match layout.variants { + abi::Variants::Empty => unreachable!("we already handled uninhabited types"), abi::Variants::Single { .. } => { // The tag of a `Single` enum is like the tag of the niched // variant: there's no tag as the discriminant is encoded diff --git a/compiler/rustc_const_eval/src/interpret/validity.rs b/compiler/rustc_const_eval/src/interpret/validity.rs index 8e18b243906..6f101395ccf 100644 --- a/compiler/rustc_const_eval/src/interpret/validity.rs +++ b/compiler/rustc_const_eval/src/interpret/validity.rs @@ -302,7 +302,7 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> { }; } } - Variants::Single { .. } => {} + Variants::Single { .. } | Variants::Empty => {} } // Now we know we are projecting to a field, so figure out which one. @@ -344,6 +344,7 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> { // Inside a variant PathElem::Field(def.variant(index).fields[FieldIdx::from_usize(field)].name) } + Variants::Empty => panic!("there is no field in Variants::Empty types"), Variants::Multiple { .. } => bug!("we handled variants above"), } } @@ -1010,7 +1011,7 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> { } // Don't forget potential other variants. match &layout.variants { - Variants::Single { .. } => { + Variants::Single { .. } | Variants::Empty => { // Fully handled above. } Variants::Multiple { variants, .. } => { diff --git a/compiler/rustc_const_eval/src/interpret/visitor.rs b/compiler/rustc_const_eval/src/interpret/visitor.rs index 76ab0bb544f..3647c109a6e 100644 --- a/compiler/rustc_const_eval/src/interpret/visitor.rs +++ b/compiler/rustc_const_eval/src/interpret/visitor.rs @@ -218,8 +218,8 @@ pub trait ValueVisitor<'tcx, M: Machine<'tcx>>: Sized { // recurse with the inner type self.visit_variant(v, idx, &inner)?; } - // For single-variant layouts, we already did anything there is to do. - Variants::Single { .. } => {} + // For single-variant layouts, we already did everything there is to do. + Variants::Single { .. } | Variants::Empty => {} } interp_ok(()) diff --git a/compiler/rustc_const_eval/src/util/check_validity_requirement.rs b/compiler/rustc_const_eval/src/util/check_validity_requirement.rs index 651a797e97c..a729d9325c8 100644 --- a/compiler/rustc_const_eval/src/util/check_validity_requirement.rs +++ b/compiler/rustc_const_eval/src/util/check_validity_requirement.rs @@ -155,6 +155,7 @@ fn check_validity_requirement_lax<'tcx>( } match &this.variants { + Variants::Empty => return Ok(false), Variants::Single { .. } => { // All fields of this single variant have already been checked above, there is nothing // else to do. |