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From: Robert A Duff <bobduff@shell01.TheWorld.com>
Newsgroups: comp.lang.ada
Subject: Re: memory management in Ada: tedious without GC?
Date: Sun, 25 May 2008 08:35:02 -0400
Organization: The World Public Access UNIX, Brookline, MA
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Date: 2008-05-25T08:35:02-04:00
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> type X is record
>    A : Boolean := False;
>    B : Integer := 1;
>    C : Boolean := False;
> end record;
>
> May the compiler group A and C and initialize both them by zeroing memory?

Yes.

> If the initialization order were fixed, that would be illegal to do.

No -- it's perfectly legal for the compiler to initialize in any order
here, because the order does not affect the semantics (and it's easy for
the compiler to prove that).

For example, the compiler could lay out the above so that A and C
are allocated in the same word, and initialize by "move 1 into B"
then "move 0 into A,C".  That's true in Ada, and it's also true
in this imaginary "Ada with init in decl order rule".

- Bob