Re: Language lawyer question: Equality on 'Access attributes

[adam@irvine.com (Adam Beneschan)]

Ze Administrator <groleau+news@freeshell.org> wrote in message news:<6bSdnYBKy_diPGCi4p2dnA@gbronline.com>...
> Robert A Duff wrote:
> >>3.10.2(24), X'Access does *not* necessarily return any sort of type
> >>implicitly defined by the language (for which no comparison operations
> >>would be defined).  The wording of this clause is:
> >>
> >>   The type of X'Access is an access-to-object type, as determined by
> >>   the expected type.
> >>
> >>The way I read this is that the type of X'Access is the expected type,
> >>which could be a program-defined type, which *would* have comparison
> >>operations defined for it.
> 
> I'd rather agree with Robert Eachus.  If 'X' and 'Y' are
> both Integers, then X'Access obviously has to be a named
> or anonymous type that is an access Integer.  Problem is,
> there could be a dozen named types visible at that point
> which are defined that way.  Some of them could be limited.
> You are asking the compiler to arbitrarily pick any visible
> non-limited 'access Integer' type, and use it for the comparison.

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.

                                 -- Adam