This looks at it only from the context of the single dev's machine. I care more about the consistency of the source code that's checked into the repository and not getting false file diffs based on white space differences, and other formatting discrepancies. And for some reason, this seems harder than it should be.
That wouldn't be hard at all. All you need to do is assign a default style and create the diffs in that style.
The hard part is creating a tool that can change between styles. Such a tool would need to be made for every language separately which is a pain. I've been wanting to try something like this for years but have never built up the courage.
Sorry, I think I misunderstood the comment I replied to. I thought he was saying it would be hard to do diffs if people restylized each file to their liking.
I'd like to see a diff tool designed around this.