Nothing really, but it mean your extensions aren't really first class syntactically. A developer has to remember that they write s.size() but not s.count_utf8_codepoints().
Bjarne Stroustrup actually has an interesting proposal to fix this by unifying free functions and method call syntax in C++17 although the proposal sounds pretty aggressive to me: http://isocpp.org/files/papers/N4174.pdf Would be an interesting change.
Bjarne Stroustrup actually has an interesting proposal to fix this by unifying free functions and method call syntax in C++17 although the proposal sounds pretty aggressive to me: http://isocpp.org/files/papers/N4174.pdf Would be an interesting change.