Re: Thin pointers and the GNAT RM

["Marc A. Criley" <mcquadex@earthlink.net>]

I've been informed that the GNAT RM is in error, the correct clause uses
Standard'Address_Size:

  type X is access all String;
  for X'Size use Standard'Address_Size;

Marc

"Marc A. Criley" wrote:
> 
> While perusing the super-secret GNAT 3.13p Reference Manual to detemine
> how to force a pointer to an unconstrained array to use a "thin"
> pointer, I found exactly what I was looking for:
> 
> To specify a thin pointer, use a size clause for the type, for example:
> 
>      type X is access all String;
>      for X'Size use System.Address'Size;
> 
> However, employing this approach in a test program...
> 
> -------------------------------------------
> with System;
> 
> procedure Pt is
> 
>    type X is access all String;
>    for X'Size use System.Address'Size;
> 
> begin
>    null;
> end Pt;
> --------------------------------------------
> 
> ...produces the following error message:
> 
> pt.adb:6:33: static integer expression required here
> 
> By replacing "System.Address'Size" with 32, the code compiles and works
> correctly.
> 
> (This information is also being sent to report@gnat.com.)
> 
> Marc A. Criley
> Senior Staff Engineer
> Quadrus Corporation
> www.quadruscorp.com