The book states:

Methods take a special first parameter, of which there are three variants: self, &self, and &mut self.

The reference uses typed self in a few places, but doesn't explain the exact rules.

The compiler also prints redundant and misleading diagnostics:

struct S;

impl S {
    fn f(self: Vec<Self>) {}
}

gives:

<anon>:6:10: 6:28 error: mismatched self type: expected `S`: expected struct `S`, found struct `collections::vec::Vec` [E0211]
<anon>:6     fn f(self: Vec<Self>) {}
                  ^~~~~~~~~~~~~~~~~~

Since replacing Vec<Self> with Box<Self> makes the code compile, "expected struct S" isn't quite correct.