this is a gcc file, you can download it and learn its usetility, for further detail please look at t

				// Test that duplicate elimination of implicit instantiations of static				// data members works properly.								// Additional sources: comdat3-aux.cc				// Additional files: comdat3.h								#include "comdat3.h"								int main ()				{				  const bool *p = &A::b;				  f ();				}