Re: Interesting effects in array renaming

[Georg Bauhaus <sb463ba@d2-hrz.uni-duisburg.de>]

Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> wrote:
: That the new view is wellcome to be inconsistent does not follow from that. 
: It is written pair lines below. BTW, for tagged types it is different and 
: semantically consistent:
: 
: procedure Foo (X : Base'Class) is
:   XX : Derived renames X;           -- Illegal
:   XX : Derived renames Derived (X); -- Legal and *CHECKED*

I'm not sure, considering

   procedure Foo (X : in out Varying'Class) is
      subtype Nono is Changeant (false);
      X1 : Changeant renames X;           -- Illegal
      X2 : Nono renames Changeant(X); -- Legal and *CHECKED*
   begin
      X2.messy := 2 * X2.messy; 
	-- constraint_error when discriminant is true
   end Foo;
 
where
package Derivs is

   type Varying (special: Boolean)
   is
     tagged record
        comp: Natural;
     end record;


   type Changeant (very_special: Boolean)
   is
     new Varying(very_special) with
      record
         case very_special is
            when true =>
               another: Boolean;
            when false =>
               messy: Integer;
         end case;
      end record;


end Derivs;


-- Georg