Re: Extending discriminant types

[Adam Beneschan <adam@irvine.com>]

On Nov 25, 2:33 pm, "Jeffrey R. Carter"
<spam.jrcarter....@spam.acm.org> wrote:
> Georg Bauhaus wrote:
>
> > But I'm lost here, is this really a bug?
>
> True, a discrete formal ["(<>)"] allows an integer actual. But consider
>
> package P is new U (N => Boolean);
>
> What is the range of Count? 0 .. True? Generic rules are supposed to be
> pessimistic; a compiler should not allow the declaration of Count just because
> the actual for N might be an integer type. So I think this is really an error.

It definitely is.  See 12.3(11); when a generic declaration and body
are compiled, the legality rules are enforced.  I won't go into which
Legality Rules apply to this specific example, but it's enough to say
that since N (a generic formal discrete type) is not an integer type,
you can't use a universal_integer where the expected type is N.

                                -- Adam