Why would a copy constructor have more than one parameter?

Question

$12.8/2 - \'A non-template constructor for class X is a copy constructor if its first parameter is of type X&, const X&, volatile X& or const

Answer 1

The old std::basic_string does have one too:

basic_string(const basic_string& s, 
         size_type pos = 0, size_type n = npos)