Where was Happy Go Lucky filmed?
1972 film by Vasily Shukshin
Happy Go Lucky (1972) was filmed in Altai Mountains, Biysk and Katun, 3 places named in its Wikipedia article, in Mongolia, Russia. Wikidata records no filming location for it at all, so the article is the only recorded source. Each place says where its claim comes from.
Places per Wikipedia's article
The Wikipedia article names 3 places. Each links to the sentence that says so.

