syntax_data: {"ast_node_type":"other","tokens":[{"end":36,"kind":"keyword","start":0,"text":"typing_env:"}]}
source_snippet:     typing_env: ty::TypingEnv<'tcx>,
context_before:     tcx: TyCtxt<'tcx>,
context_after:     mut f: impl FnMut(Option<VariantIdx>, FieldIdx, Ty<'tcx>),