Define generic comparison operator

Question

I came up with the idea to define a generic comparison operator which would work with any type, for the fun of it.

#include 
#include 

        

Answer 1

As a slight aside, the nicest way I know of writing equality operators for classes with lots of members uses this idea (this code requires C++ 14):

#include 

struct foo
{
    int x    = 1;
    double y = 42.0;
    char z   = 'z';

    auto
    members() const
    {
        return std::tie(x, y, z);
    }
};

inline bool
operator==(const foo& lhs, const foo& rhs)
{
    return lhs.members() == rhs.members();
}

int
main()
{
    foo f1;
    foo f2;

    return f1 == f2;
}

Code on Compiler Explorer