syntax_data: {"ast_node_type":"variable","tokens":[{"end":88,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let (downcast, base_proj) = variant_path.place.projection.split_last().unwrap();
context_before:         // base is an enum.
context_after:         assert_eq!(enum_place.projection.len(), base_proj.len());