* Thin pointers and the GNAT RM
@ 2001-02-02 15:05 Marc A. Criley
2001-02-02 16:43 ` Marc A. Criley
0 siblings, 1 reply; 2+ messages in thread
From: Marc A. Criley @ 2001-02-02 15:05 UTC (permalink / raw)
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
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: Thin pointers and the GNAT RM
2001-02-02 15:05 Thin pointers and the GNAT RM Marc A. Criley
@ 2001-02-02 16:43 ` Marc A. Criley
0 siblings, 0 replies; 2+ messages in thread
From: Marc A. Criley @ 2001-02-02 16:43 UTC (permalink / raw)
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
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