C++ puzzle

gistfile1.cpp

#include <iostream>

/* Under GCC 4.4.1, VERSION_1 fails but VERSION_2 and VERSION_3 work. */

#ifdef VERSION_1

void show(std::string s) {
    std::cout << s << std::endl;
}

template<class T>
void do_show(T t) {
    show(t);
}

void show(int i) {
    std::cout << i << std::endl;
}

int main(void) {
    do_show(2);
    return 0;
}

#endif

#ifdef VERSION_2

void show(std::string s) {
    std::cout << s << std::endl;
}

void show(int i) {
    std::cout << i << std::endl;
}

template<class T>
void do_show(T t) {
    show(t);
}

int main(void) {
    do_show(2);
    return 0;
}

#endif

#ifdef VERSION_3

template<class T>
void do_show(T t) {
    show(t);
}

void show(std::string s) {
    std::cout << s << std::endl;
}

void show(int i) {
    std::cout << i << std::endl;
}

int main(void) {
    do_show(2);
    return 0;
}

#endif

Only VERSION_2 is valid as per 14.6.3/1 and 14.6/9.

After I posted this Gist I made a question on Stack Overflow; this excellent answer made everything clear for me. I think you're right that only VERSION_2 is valid.