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

2024-12-01 13:12:43 +01:00
parent 37e74596c0
commit 21de42bf8d
47 changed files with 549 additions and 281 deletions
--- a/compiler/rustc_mir_transform/src/unreachable_enum_branching.rs
+++ b/compiler/rustc_mir_transform/src/unreachable_enum_branching.rs
@@ -54,7 +54,11 @@ fn variant_discriminants<'tcx>(
    tcx: TyCtxt<'tcx>,
 ) -> FxHashSet<u128> {
    match &layout.variants {
-        Variants::Single { index } => {
+        Variants::Single { index: None } => {
+            // Uninhabited, no valid discriminant.
+            FxHashSet::default()
+        }
+        Variants::Single { index: Some(index) } => {
            let mut res = FxHashSet::default();
            res.insert(
                ty.discriminant_for_variant(tcx, *index)