Question

What the best way to make a function template with the same parameters?

For example:

template<class T>
int foo(const T &item) {
    // ...
    return item;
};

template<class T, class NotUsed>
char foo(const T &item) {
    // ...
    return item;
};

int main()
{

    std::cout << foo(1)   << std::endl; // 1
    std::cout << foo('1') << std::endl; // 1

    return 0;
}

Answer 1

From what your trying to do I would suggest making the return type a template parameter.

template<class T, class Return = int>
Return foo(const T &item) {
    // ...
    return item;
};

int main()
{
    std::cout << foo<int, int>(1)   << std::endl; // 1
    std::cout << foo<char, char>('1') << std::endl; // 1
    return 0;
}