Re: GNAT GPL 2013 bug?

[Simon Wright <simon@pushface.org>]

Adam Beneschan <adambeneschan@aol.com> writes:

> On Friday, August 9, 2013 9:11:35 AM UTC-7, Simon Wright wrote:
>   
>> > In some of the examples in your later post (like the one where Q is
>> > private and the full type is a tagged record), there isn't a problem
>> > either, since the procedure isn't dispatching.
>> 
>> So when GNAT says, at the procedure call, that a null value isn't
>> allowed and that CE will be raised, it's wrong?
>
> I just tried it on a case with "type Q is private" [not tagged] and a
> full definition "type Q is tagged null record", and I didn't get a
> warning.  In the example you posted, GNAT is correct to display a
> warning, but your procedure *is* dispatching, and this situation isn't
> the same as the part of my post that you quoted.

I was talking about a slightly different case, corresponding to yours I
think:

   package Dmitry is
      type Q is private;
      procedure P (X : access Q) is null;
   private
      type Q is tagged null record;
   end Dmitry;
   with Dmitry; use Dmitry;
   procedure Test_Dmitry is
      Y : access Q;
   begin
      P (Y);                  ------ dmitry.ada:11
   end Test_Dmitry;

and get (GCC 4.8.1 and GNAT GPL 2013):

gnatmake test_dmitry.adb  -gnat12 -f
gcc -c -gnat12 test_dmitry.adb
dmitry.ada:9:04: warning: variable "Y" is read but never assigned
dmitry.ada:11:07: warning: null value not allowed here
dmitry.ada:11:07: warning: "Constraint_Error" will be raised at run time
gcc -c -gnat12 dmitry.ads
gnatbind -x test_dmitry.ali
gnatlink test_dmitry.ali