Re: Formal Subprogram Access

[AdaMagica <christ-usch.grein@t-online.de>]

Am Dienstag, 13. Februar 2018 06:51:56 UTC+1 schrieb Randy Brukardt:
> "Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org> wrote in message 
> news:p5mflm$ibq$1@dont-email.me...
> > On 02/10/2018 04:03 AM, Randy Brukardt wrote:
> >>
> >> Why do you think this is correct? I can't read 3.10.2(32/5) in a way 
> >> which
> >> would prevent using a formal subprogram in this way (assuming that the
> >> profile matches, which is does trivially in this case). Indeed, there is
> >> specifically an exception allowing "an anonymous access type of an access
> >> parameter."

This is RM 6.3.1(9).

> > IIRC, you can't take 'Access of some attributes that act as subprograms, 
> > but you can use them as the actual for a generic formal subprogram. So a 
> > generic can't take 'Access of a generic formal subprogram.
> 
> There's no such rule in the RM. As Christoph noted, a generic formal 
> subprogram has convention Ada, 'Access is allowed. If you pass an attribute 
> to it, you have to wrap it in a real subprogram for this reason. (There is a 
> lot of code specifically to do this in Janus/Ada, it probably never has been 
> tested outside of a single ACATS test -- I don't think anyone ever has had a 
> reason to pass an attribute like Succ as a formal subprogram.)

But I found no rule that the generic actual subprogram parameter must not have the Intrinsic convention.

And IIRC, I once used the 'Image attribute as actual.

So now I'm confused. Is it allowed to take 'Access of a formal subprogram? If the actual is an attribute, it is Intrinsic, so 'Access is not allowed.