syntax_data: {"ast_node_type":"other","tokens":[{"end":73,"kind":"keyword","start":0,"text":"hir::FnRetTy::DefaultReturn(_)"}]}
source_snippet:         hir::FnRetTy::DefaultReturn(_) => tcx.def_span(impl_fn.owner_id),
context_before:     let span = match fn_sig.decl.output {
context_after:         hir::FnRetTy::Return(ty) => ty.span,