In France, as a Nuclear Engineer, I was asked to give a copy of my current working contract, of my three last monthly pay documents AND those involving a bonus. Online, I found this article L-1221-6 of the Code du Travail. This states that information asked during a hiring process should be relevant to the ability of the worker to perform.
I called the free public hotline for juridic advices and they tell me "Oh, you should,'t refuse to cooperate them, but you aren't forced" but that's didn't help me, I wanted to know if it was legal or not and it feels illegal. In the end, I ended up cooperating by giving one pay document, and reminding the reader of the document of L-1221-6, I hope it goes fine for me; however I ask this question in a broad manner so that people in France who ask themselves this question can get a proper answer.