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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Comparing Access Types
Date: Wed, 15 Nov 2017 19:17:46 -0600
Organization: JSA Research & Innovation
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Xref: feeder.eternal-september.org comp.lang.ada:48928
Date: 2017-11-15T19:17:46-06:00
List-Id: <comp.lang.ada>

"Robert A Duff" <bobduff@TheWorld.com> wrote in message 
news:wccinei14g6.fsf@TheWorld.com...
>I wrote:
>
>> If "=" lies, then the Ada implementation is simply wrong.
>
> There were more than one Ada compiler for the 8086,
> and I'm pretty sure "=" on access values worked
> properly.  It's really not hard to get it right -- in
> fact I think the compiler would have to go out of
> it's way to get it wrong.

I doubt that. It wouldn't have worked "right" in Janus/Ada, for instance, we 
just did a binary comparison. So

   C000:DEAD /= CDEA:000D even though they pointed at the same physical 
memory.

But you could only run into that if you converted a System.Address into an 
access value; it would never happen within a correctly running Ada program 
so we didn't want to pay the extra cost of doing it perfectly right. (Same 
reason that I'd never waste time [mine or a programs] making zero-size 
objects work *right* in this sense.)

                                         Randy.