syntax_data: {"ast_node_type":"other","tokens":[{"end":61,"kind":"keyword","start":0,"text":"local_expn_data:"}]}
source_snippet:     local_expn_data: IndexVec<LocalExpnId, Option<ExpnData>>,
context_before:     /// first and then resolved later), so we use an `Option` here.
context_after:     local_expn_hashes: IndexVec<LocalExpnId, ExpnHash>,