10 struct S {  struct
11     constexpr int f(this const S&) {  in f()  argument
14     constexpr int f(this const S&, auto&&... args) {  in f()  argument
17     constexpr int operator[](this const S&) {  in operator []()  argument
20     constexpr int operator[](this const S& self, int i) {  in operator []()  argument
23     constexpr int operator()(this const S&) {  in operator ()()  argument
26     constexpr int operator()(this const S& self, int i) {  in operator ()()  argument
29     constexpr bool operator==(this const S& self, auto && test) {  in operator ==()  argument
32     constexpr int operator*(this const S& self) {  in operator *()  argument
35     constexpr operator Wrap<S> (this const S& self) {  in operator Wrap<S>()  argument
38     constexpr int operator <<(this Wrap<S> self, int i) {  in operator <<()  argument
46     constexpr S s;  in test()  argument