In an ideal communist society, there are no borders first off, so that's something to keep in mind.

Secondly, communists have historically, and continually, favored immigration as it does in fact grow the economy and further the growth of capitalism. I know that sounds backwards, but communists don't think capitalism doesn't have its uses, but more of see it as a stage one more go through before communism.

Source – Lenin on immigration: https://www.marxists.org/archive/lenin/works/1913/oct/29.htm

Thirdly, communists view nationalism as pretty much nonsense, anarchists refer to it as a spook.

Have I answered your question?

To be fair, that's not actually the fault of the immigrants, they're simply taking unfair deals that only they'd accept because they're desperate. It's easy to BLAME them, but the underlying issue is that people would exploit human beings in such a way in the first place. While I can't blame people for attempting to replace the labor force with robotics, as they're capable of doing repetitive tasks without getting tired, I can blame people for exploiting others by either outsourcing to countries without minimum wage or hiring people desperately fleeing for their lives who need money to buy basic necessities and have no background that could help them get a better job.