Getting string from Swift 4 new key path syntax?

How can you get a string value from Swift 4 new \keypath syntax? At this point I'm curious about any way at all, does not matter if it's complicated.

I like the idea of type information being associated with smart key path. But not all APIs and 3rd parties are there yet.

There's old way of getting string for property name with compile-time validation by #keyPath(). With Swift 4 to use #keyPath() you have to declare a property as @objc, which is something I'd prefer to avoid.