Yes, but gcc gives you no way to explain to the compiler that %Q takes a struct foobar* as argument, so either you don't use extensions, and have the seatbelts

Yes, but gcc gives you no way to explain to the compiler that %Q takes a struct foobar* as argument, so either you don't use extensions, and have the seatbelts provided by -Wformat, or you use extensions and have no seatbelts at all.