Re: type casting tagged types in the wrong

Re: type casting tagged types in the wrong

[Scott Moody]

I run this same program with GNAT 3.03 on solaris
and it reports the error correctly:

tmp.adb:24:14: downward conversion of tagged objects not allowed
gnatmake: *** compilation failed.


----source:
procedure tmp is

 type A is tagged
   record
     X : integer;
     Y : integer;
   end record;

 type B is new A with
   record
     W : integer;
   end record;

 type C is new B with
   record
     Z : integer;
   end record;

   Jim  : C;
   Jane : B;
   Save : integer;

 begin
   Jim := C (Jane);
   Save := Jim.Z;
 end;

Re: type casting tagged types in the wrong

[James A. Squire]

Scott Moody <scott@PLATO.DS.BOEING.COM> wrote:

> I run this same program with GNAT 3.03 on solaris
> and it reports the error correctly:
>
> tmp.adb:24:14: downward conversion of tagged objects not allowed
> gnatmake: *** compilation failed.
>
> ----source:
[source snipped]

I just ran it myself against the same compiler on the same platform and
to my chagrin I got the same error message.

I had figured that the bug would be consistant.  The place where I found
it
was in the Alert system that is partially coded in the Rationale.  I
added code for the other subunits besides Handle, and then I switched
the overloads of Handle so that the one for Medium Alerts called the one
for High Alerts instead of the one for Alerts.  I made sure the subunit
for Set_Alarm actually tried to read the extra field.  In this case
there was no error on the line:

Handle (HA => High_Alert(MA));

I will send this off to report@gnat.com.
--
James Squire
MDA Avionics Tools & Processes
ja_squire@csehp3.mdc.com
"one of these days I'm going to better myself by going to Knight school"