Re: "Must instantiate controlled types at library level." Why?

["Peter C. Chapin" <pchapin@sover.net>]

Ludovic Brenta <ludovic.brenta@insalien.org> wrote in news:2004512-132548-
992437@foorum.com:

> Peter, what do you mean when you say your C++ program "works"?  Does it
> print "I'm in X::f" or "I'm in Y::f"?

It "works" in the sense that Y::f was called despite the fact that 
conceptually Y::f no longer exists. What it doesn't do is produce a compile 
time error because I created a local class that was derived from a global 
class. If I understand the earlier post this is the essence of what GNAT was 
worried about when it complained that I couldn't instantiate a controlled 
type except at library level.

As I said, my earlier program probably invokes undefined behavior. I would be 
surprised if Standard C++ mandated any kind of sensible response in a case 
like this.

Peter