bjoernager/rust
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Rollup merge of #133702 - RalfJung:single-variant, r=oli-obk

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Variants::Single: do not use invalid VariantIdx for uninhabited enums

~~Stacked on top of https://github.com/rust-lang/rust/pull/133681, only the last commit is new.~~

Currently, `Variants::Single` for an empty enum contains a `VariantIdx` of 0; looking that up in the enum variant list will ICE. That's quite confusing. So let's fix that by adding a new `Variants::Empty` case for types that have 0 variants.

try-job: i686-msvc
This commit is contained in:
许杰友 Jieyou Xu (Joe) 2024-12-19 16:48:07 +08:00 • committed by GitHub
commit 2a43ce03fb
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33 changed files with 186 additions and 165 deletions
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4
compiler/rustc_codegen_ssa/src/debuginfo/mod.rs
View file

@ -65,8 +65,8 @@ fn tag_base_type_opt<'tcx>(
});
match enum_type_and_layout.layout.variants() {
// A single-variant enum has no discriminant.
Variants::Single { .. } => None,
// A single-variant or no-variant enum has no discriminant.
Variants::Single { .. } | Variants::Empty => None,
Variants::Multiple { tag_encoding: TagEncoding::Niche { .. }, tag, .. } => {
// Niche tags are always normalized to unsized integers of the correct size.

7
compiler/rustc_codegen_ssa/src/mir/place.rs
View file

@ -243,6 +243,7 @@ impl<'a, 'tcx, V: CodegenObject> PlaceRef<'tcx, V> {
return bx.cx().const_poison(cast_to);
}
let (tag_scalar, tag_encoding, tag_field) = match self.layout.variants {
Variants::Empty => unreachable!("we already handled uninhabited types"),
Variants::Single { index } => {
let discr_val = self
.layout
@ -365,9 +366,9 @@ impl<'a, 'tcx, V: CodegenObject> PlaceRef<'tcx, V> {
return;
}
match self.layout.variants {
Variants::Single { index } => {
assert_eq!(index, variant_index);
}
Variants::Empty => unreachable!("we already handled uninhabited types"),
Variants::Single { index } => assert_eq!(index, variant_index),
Variants::Multiple { tag_encoding: TagEncoding::Direct, tag_field, .. } => {
let ptr = self.project_field(bx, tag_field);
let to =