From the C++ standard, 7.5p1:

Two function types with different language linkages are distinct types even if they are otherwise identical.

The following code tests for this and should compile (a successful compile indicates a test pass).

template <bool>
struct static_assert;

template<>
struct static_assert<true> {};

extern "C"
{
char myexit(void (*)(void));
typedef void (*CF)(void);
}

int myexit(void (*f)())
{
    static_assert<sizeof(myexit((CF)f)) == 1> e1;
    return myexit((CF)f);
}

int main()
{
}

extern "C"
{
char myexit(void (*)(void))
{
    return 0;
}
}