Class B

examples/all_features/stringification.cpp:22–26

namespace N {
struct A {};
struct B {
    friend std::ostream &operator<<(std::ostream &os, const B &) {
        return os << "B";
    }
};
struct C {};
static std::ostream &operator<<(std::ostream &os, const C &) {
    return os << "C";