prog.cpp: In function 'int main()':
prog.cpp:17:10: error: no matching function for call to 'B::func_1()'
b.func_1();}
^
prog.cpp:10:16: note: candidate: void B::func_1(int)
void func_1(int a) {}
^
prog.cpp:10:16: note: candidate expects 1 argument, 0 provided