Re: Language lawyer question: Equality on 'Access attributes

[Dmitry A. Kazakov <mailbox@dmitry-kazakov.de>]

On Thu, 08 Jan 2004 23:10:44 -0500, Ze Administrator
<groleau+news@freeshell.org> wrote:

>Adam Beneschan wrote:
>> No, I'm not.  If there are a dozen named access-to-integer types
>> directly visible at that point (which would mean that their "="
>> operators are also visible), the RM rules clearly say that "=" would
>> be ambiguous.  I think I briefly touched on that situation in my
>> original post.  The question is, what should happen when only one such
>> "=" operator is a possibility.
>
>Every construct that implies a type without naming it
>effectively declares an anonymous type, right?  Can any
>two constructs 'declare' the same anonymous type?

No, but it is not that simple, because anonymous types aren't matched
by names. This works fine with unary operations, but might be
problematic with n-ary ones (like = is). It could be easy to do if ARM
would define sort of "universal access type" as it does for integers.
But this not the case. Annex K only states:

"...The type of X�Access is an access-to-object type, as determined by
the expected type. The expected type shall be a general access type.
See 3.10.2."

What is the "expected type" in the case of X'Access = Y'Access? There
is no one! So I think that GNAT formally does not contradict the
standard.

--
Regards,
Dmitry A. Kazakov
www.dmitry-kazakov.de