Class-qualified annotation expressions

The wonderfully useful specification of type annotation expressions describes what kinds of expressions are valid type annotations.

I believe the spec does not include a case which type checkers support, although as we will see this comes down to semantics :)

class A:
    class B:
        pass

x: A.B = A.B()

The A.B annotation seems to fall under the name rule:

| name
      (where name must refer to a valid in-scope class,
       type alias, or TypeVar)

The spec helpfully continues:

Any leaf denoted as name may also be a qualified name (i.e., module '.' name or package '.' module '.' name, with any level of nesting).

The concept of a "qualified name" occurs only in this section, and the parenthetical explanation serves as it's most precise definition, as far as I can tell.

Should we extend the definition of "qualified name" to also include class members? Or maybe I should read the class as a "module" or a "package" and the existing definition suffices?

从类型和注解表达式规范开始，尤其是 name 和 qualified name 的定义，并将其与 issue 中的 A.B 示例进行比较。检查现有类型检查器如何解释类限定注解；当规范明确说明是否包含类成员以及如何涵盖该示例时，即视为完成。