Why do you have to call `req.Body.Close()`? Does Go not have RAII?

Does Go have something analogous to Rust's `try!` or `?` operator, which would turn it into (pseudocode):

    contents, err := try!(ioutil.Readall(req.Body))

Or:

    contents, err := ioutil.Readall(req.Body)?

If not, why not?

(I don't know Go)