Rollup merge of #110943 - RalfJung:interpret-unsized-arg-ice, r=oli-obk

interpret: fail more gracefully on uninit unsized locals

r? `@oli-obk`

Fixes https://github.com/rust-lang/rust/issues/68538

1 files changed, 6 insertions, 0 deletions

diff --git a/compiler/rustc_const_eval/src/interpret/operand.rs b/compiler/rustc_const_eval/src/interpret/operand.rs
index 5310ef0bb3e..a7f66071fe2 100644
--- a/compiler/rustc_const_eval/src/interpret/operand.rs
+++ b/compiler/rustc_const_eval/src/interpret/operand.rs
@@ -245,6 +245,12 @@ impl<'tcx, Prov: Provenance> ImmTy<'tcx, Prov> {
 impl<'tcx, Prov: Provenance> OpTy<'tcx, Prov> {
     pub fn len(&self, cx: &impl HasDataLayout) -> InterpResult<'tcx, u64> {
         if self.layout.is_unsized() {
+            if matches!(self.op, Operand::Immediate(Immediate::Uninit)) {
+                // Uninit unsized places shouldn't occur. In the interpreter we have them
+                // temporarily for unsized arguments before their value is put in; in ConstProp they
+                // remain uninit and this code can actually be reached.
+                throw_inval!(UninitUnsizedLocal);
+            }
             // There are no unsized immediates.
             self.assert_mem_place().len(cx)
         } else {