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From: Victor Porton <porton@narod.ru>
Newsgroups: comp.lang.ada
Subject: Re: Unchecked_Union record inside an other record - trouble
Date: Fri, 08 Aug 2014 23:28:13 +0300
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Date: 2014-08-08T23:28:13+03:00
List-Id: <comp.lang.ada>

Shark8 wrote:

> On 08-Aug-14 14:12, Victor Porton wrote:
>> You forgot "with Unchecked_Union". Certainly your code does not work.
> 
> There's no unchecked union on T2, that was T in your example.
> 
>>
>>    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;
> 
> See?

GNAT 4.9 produces no warnings for the below program.

Which compiler do you use? I suspect it is a bug in your compiler.

Or do we speak about different Ada code?

-- main.adb
with Interfaces.C; use Interfaces.C;

procedure Main is

   type Kind is (First, Second);

   type T(K: Kind := Kind'Last) is
      record
         case K is
            when First =>
               X: int;
            when Second =>
               Y: char;
         end case;
      end record
      with Unchecked_Union, Convention=>C;

   type Container is
      record
         Z: int;
         R: T;
      end record;

   function P (C: Container) return char is
   begin
      return C.R.Y;
   end;

begin
   null;
end;


-- 
Victor Porton - http://portonvictor.org