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Newsgroups: comp.lang.ada
Subject: Re: Default rep specs for record types - documented??
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From: Stephen Leake <stephen_leake@acm.org>
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Date: Sat, 05 Nov 2005 05:14:10 -0500
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Date: 2005-11-05T05:14:10-05:00
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"Ed Falis" <falis@verizon.net> writes:

> But if you order the components the same in both languages, and use
> pragma  Convention (C, ...) on the Ada side, the Ada record layout
> will match the  C struct layout.

This has always bothered me, because it is so poorly defined.

Which C compiler? With which settings of the various layout options?

If I'm compiling with GNAT, I could guess that it's 'gcc' and 'the
defaults'; but the point of rep clauses is to not guess. 

But if I'm compiling with GNAT and trying to interface to Borland C
with the equivalent of 'pack structs', it's just plain wrong.

On VAX and Alpha, this might have some meaning, because DEC defined a
binary API. But on x86, it's just a guess.

-- 
-- Stephe