{"ast_node_type":"variable","tokens":[{"end":59,"kind":"keyword","start":0,"text":"if"}]}
        if let DefiningTy::FnDef(def_id, _) = defining_ty {
        // (as it's created inside the body itself, not passed in from outside).
            if self.infcx.tcx.fn_sig(def_id).skip_binder().c_variadic() {