규칙 8.15

A member declared private may be named only inside the body of the class that declares it, and one declared protected only inside the bodies of that class and of the classes that extend it, on an object of the naming body’s own class or of one that extends it; a name either rule does not allow must be refused with the remedy. The declaration a name is checked against is the one the class whose body holds it sees, whichever class that body is compiled for (Rule 8.9), and a field a derived class declares again without a modifier is public, as TypeScript allows. An object literal cannot build a class with a private or protected field, and a spread and a destructuring pattern leave such a field out, as they leave out a private name (Rule 8.12).