syntax_data: {"ast_node_type":"other","tokens":[{"end":59,"kind":"keyword","start":0,"text":"assert!(matches!(base,"}]}
source_snippet:                 assert!(matches!(base, AdtExprBase::None));
context_before:             ExprKind::Adt(box AdtExpr { variant_index, fields, base, .. }) => {
context_after:                 assert!(fields.is_empty());