main.cpp

#include <iostream>
#include <iomanip>
#include <type_traits>
#include <sstream>

#include <boost/tti/has_member_function.hpp>

struct int_size{
	int size() const { return 42; };
};

struct derived_int_size : int_size{};

struct size_t_size{
	std::size_t size() const { return 42; }
};

struct derived_size_t_size : size_t_size{};

struct void_size{
	void size() {}
};

struct no_size{};

struct template_int_size{
	template<typename=int>
	int size() const { return 42; }
};

struct overloaded_size{
	size_t size() const { return 42; }
	int size() { return 41; }
};


BOOST_TTI_HAS_MEMBER_FUNCTION(size)

int main()
{
	using namespace std;
//#define dbg(x) { stringstream s; s << boolalpha << left << setw(8) << has_size_method2<x>::value << #x; cout << s.str() << endl; }

#define dbg(x) { stringstream s; s << boolalpha << left << setw(8) <<\
	(has_member_function_size<x,size_t,boost::mpl::vector<>, boost::function_types::const_qualified>::value ||\
	has_member_function_size<x,int,boost::mpl::vector<>, boost::function_types::const_qualified>::value)\
	<< #x; cout << s.str() << endl; }

	dbg(int_size);
	dbg(derived_int_size);
	dbg(size_t_size);
	dbg(derived_size_t_size);
	dbg(void_size);
	dbg(no_size);
	dbg(template_int_size);
	dbg(overloaded_size);
}

output.txt

true    int_size
false   derived_int_size
true    size_t_size
false   derived_size_t_size
false   void_size
false   no_size
true    template_int_size
true    overloaded_size