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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Q: setting an address with pure?
Date: Thu, 16 Jul 2015 14:14:29 -0500
Organization: Jacob Sparre Andersen Research & Innovation
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Date: 2015-07-16T14:14:29-05:00
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"Brian Drummond" <brian@shapes.demon.co.uk> wrote in message 
news:mo7t28$6h2$1@dont-email.me...
> On Wed, 15 Jul 2015 08:50:06 -0700, rrr.eee.27 wrote:
...
>> I made the type System.Address globaly visible as a 32-bit unsigned.
>> That's why the above statements work in AVR-Ada and probably in MSP-Ada
>
> Ah! Well if that is permitted by the LRM (and obviously, only for targets
> where it is valid) it certainly makes life easier!

It's permitted by the RM. There is Implementation Advice that System.Address 
be a private type, but of course the reason that it is advice is that it 
might not be appropriate to all implementations. In this particular case, 
though, its advice mainly because it would have been incompatible on some 
implementations to make it private (Janus/Ada is in that category); I think 
the feeling was that new implementations should have it private. (But we now 
know that's clearly wrong if preelaboration is going to be used with 
hardware access.)

Hopefully, Ada 202x will find a solution to this problem (and maybe even in 
the 2018 update), so it's fixed for good rather than depending on the 
goodness of your RTS implementer (many who are likely to be unaware of this 
problem).

                               Randy.