syntax_data: {"ast_node_type":"other","tokens":[{"end":62,"kind":"keyword","start":0,"text":"Res::Def(DefKind::ConstParam,"}]}
source_snippet:                     Res::Def(DefKind::ConstParam, def_id) => {
context_before:                 let e = match res {
context_after:                         let const_span = self.tcx.def_span(def_id);