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Fix a variant index and variant discriminant confusion

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Previously for enums using the `Variants::Single` layout, the variant
index was being confused with its discriminant. For example, in the case
of `enum E { A = 1 }`.

Use `discriminant_for_variant` to avoid the issue.
This commit is contained in:
Tomasz Miąsko 2021-10-11 00:00:00 +00:00
parent d5a91f3114
commit c3e71d83cd
1 changed files with 4 additions and 1 deletions
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5
compiler/rustc_mir_transform/src/uninhabited_enum_branching.rs
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@ -55,7 +55,10 @@ fn variant_discriminants<'tcx>(
match &layout.variants { match &layout.variants {
Variants::Single { index } => { Variants::Single { index } => {
let mut res = FxHashSet::default(); let mut res = FxHashSet::default();
res.insert(index.as_u32() as u128); res.insert(
ty.discriminant_for_variant(tcx, *index)
.map_or(index.as_u32() as u128, |discr| discr.val),
);
res res
} }
Variants::Multiple { variants, .. } => variants Variants::Multiple { variants, .. } => variants