mingw32/bin/ld.exe: C:\Users\mfrom\AppData\Local\Temp\ccSKcRks.o:PizzaPi.cpp:(.text$_ZN5PizzaC2Ev[__ZN5PizzaC2Ev]+0xa): undefined reference to `vtable for Pizza' collect2.exe: error: ld returned 1 exit status

virtual void process() = 0;