syntax_data: {"ast_node_type":"import","tokens":[{"end":63,"kind":"keyword","start":0,"text":"//"}]}
source_snippet: // for `Instance` (e.g. typeck would use `Ty::fn_sig` instead),
context_before: // `fn_abi_of_instance` - any other uses are either too high-level
context_after: // or should go through `FnAbi` instead, to avoid losing any