I never use inheritance or polymorphism in my own code (even my C++ code), and almost never even have a reason to think about using it to solve a problem (there's almost always a better, cleaner way). However, I recently came across this really old reddit comment:
As an interesting exercise I figured I'd play around with his method and in the unlikely event I ever want to use C++ style inheritance in C (or any kind of inheritance really), I'll have this as an option. The only think I can think of using it for is porting others' inheritance based C++ code to C without having to completely redesign it. We'll see how it goes.