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From: denreimer@aol.com (DenReimer)
Subject: Re: Elaboration order
Date: 1996/03/20
Message-ID: <4io8rn$gfn@newsbf02.news.aol.com>#1/1
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reply-to: denreimer@aol.com (DenReimer)
newsgroups: comp.lang.ada
Date: 1996-03-20T00:00:00+00:00
List-Id: <comp.lang.ada>

Here's something that I'm trying to do in Ada83 and Ada95:

with GENERIC_PACKAGE;
package A_PKG is
   package INSTANCE is new GENERIC_PACKAGE ( ... );
   X : INTEGER := INSTANCE.SOME_FUNCTION;
end A_PKG;

The elaboration of X requires that the instantiated package INSTANCE be
elaborated first (both spec and body.)  The compiler will not let me use
pragma elaborate (INSTANCE);

It is not clear to me what the elaboration order should be in the case of
nested packages.  I would like to assume that for nested packages, the
elaboration is also nested.  In the case of generic instantiations, both
spec and body would be elaborated at the point of instantiation. 
Unfortunately, the LRM does not seem to make any requirements regarding
elaboration order for nested packages.  I've tried the above source code
with Ada/ED and an Alsys Ada83 compiler and it seems to work OK.

When I use gnat, I get a program error.  The Ada95 pragmas used for
controlling elaboration order seem to only apply to library units.  In the
example above, I believe that INSTANCE is a program unit but not a library
unit.  Is there some way I can force the elaboration of INSTANCE to occur
immediately?  The only other alternative I can think of is to create
another compilation unit just for the instantiation so that INSTANCE will
then be a library unit.

Thanks,
Dennis Reimer