How to detect methods that can have a more restrictive access specifier

I would like to analyze a bunch C++ source code files to detect if any of the methods of the defined classes may have a more restrictive access specifier. The simple case would be methods that at the beginning were declared as public but later on only the owner class invokes them, so they could be moved to private.

Is there any automatic tool for that? I'm working in Linux, the code is C++11-compliant, and I'm playing with several clang tools, in order to build my own, but if anyone can point me to an already existing tool it will be very much appreciated.