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Date: Fri, 08 Aug 2014 21:21:06 +0200
From: Per Sandberg <per.s.sandberg@bahnhof.se>
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Newsgroups: comp.lang.ada
Subject: Re: Unchecked_Union record inside an other record - trouble
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Date: 2014-08-08T21:21:06+02:00
List-Id: <comp.lang.ada>

You shall not try to write interface code by hand you shall use the 
compiler
	gcc -c -fdump-ada-spec <more arguments and files>
see GNAT Users guide.

Since humans makes a heap load of errors and erronous asumptions when 
they try to translate the contents of a .h file to an .ads file, the 
compiler does a much better job.

/Per


On 08.08.2014 17:36, Victor Porton wrote:
> I am trying to interface my program with a C library.
>
> The below program does not compile:
>
> main.adb:19:14: unconstrained subtype in component declaration
>
> If this does not work, what should I do to interface a union inside a struct
> in a C library?
>
> -- main.adb
> with Interfaces.C; use Interfaces.C;
>
> procedure Main is
>
>     type Kind is (First, Second);
>
>     type T(K: Kind) is
>        record
>           case K is
>              when First  => I: int;
>              when Second => C: char;
>           end case;
>        end record
>     with Unchecked_Union, Convention=>C;
>
>     type T2 is
>        record
>           Z: int;
>           Ob: T;
>        end record
>     with Convention=>C;
>
> begin
>     null;
> end;
>