Option comes with utility methods for various transformations, which are listed in its documentation. For any T that implements Clone (which String does), Option<&T>::cloned does what you’re looking for.
Clone is more specific than ToOwned, so .cloned() isn’t an exact match for .map(|x| x.to_owned()). For example, it won’t turn an Option<&str> into an Option<String>; for that you will have to stick with map.
Since Rust 1.35, when T is Copy, .copied() does the same thing as .cloned(), but it will fail to compile when T is not Copy. You might use this when you want to be explicit that the clone is cheap.
See also:
- How to clone last element from vector?
- Get the last element of a vector and push it to the same vector