Re: A hole in Ada type safety

[AdaMagica <christ-usch.grein@t-online.de>]

On 13 Mai, 02:47, a...@att.net wrote:
> --
> --  May be this program will help explain the problem.
> --

(erased a lot of irrelevant stuff)

>   -- ------------------ --
>   --  Ada05_Conversion  --
>   -- ------------------ --
>   generic
>     type Source (<>) is limited private ;
>     type Target (<>) is limited private ;
>     function Ada05_Conversion ( S : Source ) return Target ;
>
>   function Ada05_Conversion ( S : Source ) return Target is
>
>       pragma Suppress ( All_Checks ) ;
>
>     begin
>       -- Compiling Error messages:
>       --   (Ada 2005) cannot copy object of a limited type
>       --              (RM-2005 6.5(5.5/2))
>       --   consider switching to return of access type
>       --
>       -- Additional References for reasoning:
>       --   RM 7.5 Limited Types ( 1/2, 1.a, 1.b/2 )
>       --
>       return Target ( S ) ;

What you are writing here is a normal type conversion with certain
rules (RM 4.6), not an unchecked type conversion (RM 13.9). For a type
conversion to be legal, the types involved have to be convertible.
Source and Target are not convertible, so this whole thing is illegal
for several reasons.

>     end Ada05_Conversion ;

RTFM