#include <type_traits>

template <typename T>
typename std::enable_if<std::is_floating_point<T>::value, T>::type float_sum(T value, T value2)
{
	return value + value2;
}

int main()
{
	double x = float_sum(1.0, 2.0);	// It compiles
	float y = float_sum(2.0, 2.0);	// It compiles
	int z = float_sum(3, 3);		// It doesn't compile
	return 0;
}