public aliases to private/package symbols

[Martin Nowak]

> The issue is not with aliases, accessability already has a natural grey
> area:
>
> ====================
> module lib;
>
> private struct Foo {}
>
> // Should any of these be allowed?
> public Foo getFoo() { return Foo(); }
> public void takeFoo(Foo f) {}
> struct Bar
> {
>     Foo f;
> }
>
> ------
>
> module main;
> import lib;
>
> getFoo();  // Allowed?
>
> takeFoo(getFoo());  // Allowed?
>
> Bar b;  // Allowed?
>
> takeFoo(b.f);   // Allowed?
>
> b.f = getFoo();   // Allowed?
>
> // Allowed? If so, can you *do* anything with x?
> auto x = getFoo();
>
> ====================
>
The solution seems to be to check protection only during symbol lookup.
Thus all of the above are allowed and you can do with x what Foo allows  
you to
(aggregates default to public protection).