Re: why "unconstrained subtype in component declaration" while said component given default value ?

[Shark8 <onewingedshark@gmail.com>]

On Saturday, May 26, 2018 at 3:03:23 PM UTC-6, Mehdi Saada wrote:
> Hello.
> Why is this case not allowed ? Is there really an implementation issue here ? I doubt so. Why should it be any different from the non-issue of initializing variables of unconstrained subtypes vs declaring uninitialized variables of constrained subtypes ?
>  type A (N: Positive) is record
>       II : Integer;
>       Chaine : String := Give_String(N);
>    end record;

It is allowed; try:
  type A (N: Positive) is record
       II : Integer;
       Chaine : String(1..N) := Give_String(N);
    end record;
(This assumes the output-size of Give-string is length N.)

> 
> Also, there's something that would be really cool, and I'm curious why it could not be allowed: Why can't we provide a private constrained subtype, of an inconstrained private type ?
> 
> package III is
>    type A (<>) is private;
>    subtype B is A;  -- should be a constrained subtype
> private
>    function Donne_String (N : Positive) return String;
>    type A (N: Positive) is record
>       II : Integer;
>       Chaine : String(1..N) := Give_String(N);
>    end record;
> end III;

What's the use-case for this?