Many years ago I travelled in Poland with a Polish phrase book and asked people about a “szynk.” The only thing I managed to find out was that it was (at that time) a hopelessly outdated expression.

I guess yes. Pub (pronounced the English way) is also possible, and then there may be some more specific and/or colloquial words. Or just using the place's own name.

But on the flip-side when I hear the word 'bar' used in Poland, most often it is in reference to something like a snack-bar, or bar mleczny not a place for alcohol.

As an English speaker when I here the word 'bar' I think of a place to buy and consume alcohol, which may happen to sell some very basic food like chips or finger food.

I have often heard the word "knajpa" used as well, which is shown in some dictionaries as a pub or tavern. I assume it is a loanword from the German "kneipe"., and is also used in Ukrainian and Czech, as well as other Germanic languages.

To my sassenach mind, the words "bar" and "pub" conjure up different images. Which is meant by the Polish word "bar" is a different question however.....