Trying to reply in this question, I found this interesting link: https://www.communia-association.org/2015/01/23/the-little-prince-almost-in-the-public-domain/
This is a 2016 article talking about the public domain status of Le Petit Prince in particular and the public domain harmonisation in general. An excerpt follows:
If you know a bit about the rules for determining when a work goes out of copyright, we can assume that on 1st January 2015 “The Little Prince” became part of the public domain. This is because in France copyright lasts for 70 years after the death of the author. And since Saint-Exupéry died in 1944, this would put “The Little Prince” into the public domain in France.
However, the harmonization of the duration of copyright is not uniform. In France, works of authors who died for France during the First and Second World Wars benefit from additional copyright protection. Copyright for works created by these authors is extended for an additional 30 years to compensate for the losses and difficulties in the commercial exploitation of their works during the war.
Beginning this year, “The Little Prince” is in the public domain almost everywhere in Europe. But in France, the novel will pass into the public domain sometime between 1 May 2033 and 1 January 2045, depending on your interpretations of the rules! Interestingly, Canadians have been freely using “The Little Prince” for the last 20 years, as copyright expires there 50 years after the death of the creator.
My question is what is the current status of the public domain in France. Having found the text of Le Petit Prince available online (see also here), does that mean the aforementioned French Law has been changed since 2016?