Ambiguous injected class name is not an error

Question

What I read in the C++ standard about injected class names contradicts (as I see it) with the behavior of a sample program I will present shortly. Here\'s what I read:

Answer 1

I found it! It's right there in the standard! I was right! It should be ambiguous!

Clause 14.6.1 Paragraph

A lookup that finds an injected-class-name (10.2) can result in an ambiguity in certain cases (for example, if it is found in more than one base class). If all of the injected-class-names that are found refer to specializations of the same class template, and if the name is followed by a template-argument-list, the reference refers to the class template itself and not a specialization thereof, and is not ambiguous. [Example:

template  struct Base { };
template  struct Derived: Base, Base 
{ 
    typename Derived::Base b; // error: ambiguous typename 
    Derived::Base d;  // OK 
};

—end example]

Bottom line: This is yet another Microsoft compiler BUG. Disabling language extensions doesn't help either.