syntax_data: {"ast_node_type":"other","tokens":[{"end":72,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:                 // upvars, of which a `ty::FnDef` doesn't have any), but
context_before:                 // and with `ty::Closure` (ignoring all args other than
context_after:                 // consistent with previous (accidental) behavior.