{"ast_node_type":"other","tokens":[{"end":47,"kind":"keyword","start":0,"text":"self.demand_eqtype(span,"}]}
        self.demand_eqtype(span, ty, fallback);
        let span = ty.ty_vid().map_or(DUMMY_SP, |vid| self.infcx.type_var_origin(vid).span);
        self.fallback_has_occurred.set(true);