#999 spurious error on derived record passed as Out parameter

[Eric Botcazou]

The error message is:

p.adb:7:03: unconstrained subtype not allowed (need initialization)
p.adb:7:03: provide initial value or explicit discriminant values
p.adb:7:03: or give default discriminant values for type "Rec"

and is issued by every compiler I tried.  This doesn't happen if the parameter 
is In Out instead of Out.  The problem is that the compiler doesn't initialize 
the temporary it creates around the call in the Out case.  This blocks the 2nd 
part of the fix for R914-006.

-- 
Eric Botcazou

with Q; use Q;

procedure P is
  D : Derived;
begin
  Proc1 (Rec (D));
  Proc2 (Rec (D));
end;

package Q is

   type T_Unsigned8  is new Natural range 0 .. (2 ** 8 - 1);

   type Rec (Discriminant : T_Unsigned8) is record
      Fixed_Field : T_Unsigned8;
      case Discriminant is
         when 0 =>
            Optional_Field : T_unsigned8;
         when others =>
            null;
      end case;
   end record;

   type Derived is new Rec (0);

   for Derived use record
      Fixed_Field    at 0 range 0  .. 7;
      Discriminant   at 0 range 8  .. 15;
      Optional_Field at 0 range 16 .. 23;
   end record;

   procedure Proc1 (R : in out Rec);

   procedure Proc2 (R : out Rec);

end Q;