This song slipped into Australian singers' repertoires as just "The French Song", but it was often sub-titled "When the Sun Says Goodbye to the Mountains". It's usually sung in the English translation. A friend of mine learned it in about 1950, in Queensland. I remember it from around the same time in Melbourne, but in French.
I came across a hand written copy in a junk shop in Melbourne, in English, about 30 years ago and it had a funny mis-spelling on the word "mountains". It was given as "mounties" so that you get some strange images especially of the girl ON the MOUNTIES.
Someone smarter than me will probably post the tune. Joy