syntax_data: {"ast_node_type":"other","tokens":[{"end":45,"kind":"keyword","start":0,"text":"*old_expn_data"}]}
source_snippet:             *old_expn_data = Some(expn_data);
context_before:             assert!(old_expn_data.is_none(), "expansion data is reset for an expansion ID");
context_after:             debug_assert_eq!(data.local_expn_hashes[self].0, Fingerprint::ZERO);