syntax_data: {"ast_node_type":"other","tokens":[{"end":39,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // FIXME requires optimized MIR
context_before:     fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> {
context_after:         FIRST_VARIANT..tcx.coroutine_layout(def_id, self.args).unwrap().variant_fields.next_index()