{"ast_node_type":"variable","tokens":[{"end":75,"kind":"keyword","start":0,"text":"let"}]}
        let fun_features = &self.codegen_fn_attrs(fun_def).target_features;
    ) -> Option<ty::Binder<'tcx, ty::FnSig<'tcx>>> {
        let callee_features = &self.codegen_fn_attrs(caller).target_features;