[jankins]

> You can make `rustc` happy by following suggestions, but may end up puzzled as to the reasons for the changes it suggests.

This is how I felt, but it wasn't bad: I think you start to pick up on the patterns. In other words, learning isn't short-circuited after you've made rustc happy, even though you're still a bit puzzled - you'll carry the experience along with you and continue to learn from it later.