Rule around non-dispatchable functions doesn't match the compiler behavior

In the Object Safety section, it says:

• Explicitly non-dispatchable functions require:
  • Have a where Self: Sized bound (receiver type of Self (i.e. self) implies this).

This implies that if you have any associated function with receiver of self should be counted as non-dispatchable function. However, it is not the case. See the following code:

trait Foo {
    fn a(self);
    // fn b(self, x: &Self);
    // fn c(self) -> Self;
}

fn test() -> Box<dyn Foo> { todo!() }

Uncommenting b or c would make the code fail to compile, unless explicit where Self: Sized is added, but the rule in the reference indicates that having a receiver self already implies that bound exists.

Not sure whether it's something that should be fixed in the reference or the compiler.

Start with the Object Safety section in the Rust Reference and compile the provided Foo examples, including the commented-out methods, to compare the wording with compiler behavior. Determine whether the reference rule or the compiler behavior is incorrect, then update the documentation or clarify the discrepancy so the stated requirements match the observed behavior.