Re: Null Record is not always Null

[prichtmyer@yahoo.com (Peter Richtmyer)]

Robert A Duff <bobduff@shell01.TheWorld.com> wrote in message news:<wccn0pmpan6.fsf@shell01.TheWorld.com>...

> I'm curious: why do you care what the size of a null record is,
> or an array of them?  It's rather unusual to create large numbers of
> null records!
> 
Thought somebody might ask. I am passing two structures (types) as 
generic parameters to a generic package. For some instantiations of the 
generic, one of the structures could be "null" - and I wanted to be 
able to test for null by testing the T'size of that structure 
in the generic package. But for portability I will probably pass a 
separate numeric "type_T_size" parameter so I do not need to rely on T'size
being zero when it is null.

There was really no practical reason to create arrays of the null
record type, I was just curious.   :-)    or is it   :-?

> Are you implying that you got this output with the above lines *not*
> commented out?  If that's the case, then it's clearly a bug -- if the
> compiler isn't going to give back 0, then it shouldn't let you specify 0
> -- it must give a compile-time error.
> 
My mistake - I meant to include the program without any lines commented 
out. I got those results from Gnat with all source code "active". I think
it is a Gnat bug, but I am only running with the freebie Gnat right now.

thanks all,
Peter