Developers wishing to (re)construct buildings must first receive a building permit. This can take 2 to 3 years. In France, the “Abbé Pierre” association offers homeless people to come and live in the dwellings that will later be demolished. This saves costs for the owners of the land, as they no longer need to protect it from potential squatters. I find this system really ingenious, because everyone wins. It’s an association made up of volunteers that manages this, and it would be nice if the state took over and made this kind of practice official.