I have a struct that stores a couple generic callbacks. In my test suite, I'm trying to create a specific instance of that struct in a setup function. But I can't figure out what to return when the function callback is a closure.
I made a basic repro; the crux is, what goes in <???> below?
Though that worked with my toy example, it gave me a "expected fn pointer, found closure" error in my own code. I really can't figure out why the toy example didn't do that too.
My solution, based on your hint was to just return Tracker<impl Fn(u32) -> u32>