{"ast_node_type":"variable","tokens":[{"end":53,"kind":"keyword","start":0,"text":"if"}]}
        if let ty::FnDef(def_id, _) = *fn_ty.kind() {
        let fn_ty = callee.ty(self.body, self.tcx);
            if self.tcx.is_promotable_const_fn(def_id) {