How can I check whether a member function has const overload?

Question

Lets say I have

struct foo {
    void ham() {}
    void ham() const {}
};

struct bar {
    void ham() {}
};

Assuming I have a templated fu

Answer 1

With

#define DEFINE_HAS_SIGNATURE(traitsName, funcName, signature)               \
    template                                                    \
    class traitsName                                                        \
    {                                                                       \
    private:                                                                \
        template struct helper;                              \
        template                                                \
        static std::uint8_t check(helper*);           \
        template static std::uint16_t check(...);               \
    public:                                                                 \
        static                                                              \
        constexpr bool value = sizeof(check(0)) == sizeof(std::uint8_t); \
    }

DEFINE_HAS_SIGNATURE(has_ham_const, T::ham, void (T::*)() const);

And then

static_assert(has_ham_const::value, "unexpected");
static_assert(!has_ham_const::value, "unexpected");

Demo