{"ast_node_type":"variable","tokens":[{"end":65,"kind":"keyword","start":0,"text":"let"}]}
                let inner = self.ecx().project_downcast(v, idx)?;
                // - variant.abi.is_uninhabited(): triggers UB in `read_discriminant` so we never get here.
                trace!("walk_value: variant layout: {:#?}", inner.layout());