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Newsgroups: comp.lang.ada
Date: Thu, 9 Apr 2015 06:28:57 -0700 (PDT)
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Subject: Re: GNAT "alignment value must be positive"
From: marciant@earthlink.net
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Xref: news.eternal-september.org comp.lang.ada:25489
Date: 2015-04-09T06:28:57-07:00
List-Id: <comp.lang.ada>

On Wednesday, April 8, 2015 at 4:35:23 PM UTC-4, Randy Brukardt wrote:
> ...
>
> I should have added that the Recommended Level of Support does seem to=20
> require supporting that (probably should have read it before pushing=20
> "send"!), so in that sense, it's a GNAT bug to not allow it. But=20
> practically, 0 and 1 are the same for a specified alignment; nothing is=
=20
> going to be different about the default allocation, so it's doesn't reall=
y=20
> matter.
>=20
>                                             Randy.

Are you saying that it is not necessary to specify alignment zero for recor=
ds that end up specifying components of enclosing records whose layout is b=
eing fully "rep-spec'd" (pragma Pack is not being used?).
Is it not (no longer?) necessary to ever indicate - as per Ada 95 RM 13.3 [=
14] - "zero means that the object is not necessarily aligned on a storage e=
lement boundary."?  Should "object" in the above really be "subtype" or obj=
ect?  Is it no necessary to indicate "not necessarily aligned on a storage =
element boundary" for anything?

I know that those are a lot of questions but I am trying to understand enou=
gh to gain "full command" of this aspect of the language: I have always (at=
 this point about 25 years!) been very interested in hardware and communica=
tion interface design in Ada.