Re: "unconstrained subtype in component declaration" vs "discriminant in constraint must appear alone"

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

0012...@gmail.com schrieb am Donnerstag, 25. Februar 2021 um 01:13:32 UTC+1:
> But I'm assigning a record aggregate to a mutable type object (so with a default disciminant). 
> So why does it matter if the component's subtype is constrained (here by the discriminant, but whatever) ? 
> It's the very point of mutable objects, to cope with these assignments... or What am I missing ? 
> That's the last issue remaining.

First a word to your attitude.

You ask us a favour to look at your code. That's OK and you're welcome.
But: You ask us to do some work for you. Then may we not expect that you do your work before?

What is your work?

Provide a complete compilable reproducer.
Write it in a consitent and readable style.

Is this expectation on our side really too much?

> type Sets_of_Card is array (Nombre_cartes range <>) of Cards;
> type CARDS_SETS (Nb: Nombre_cartes := 0) is record
> Set: Sets_of_Card (1..Nb) := INITIALIZATION (Nb);
> end record;

> PACK := (pack.nb-1, Pack.Set(pack.set'First..Pack.Nb-1));

This line by itself is not the problem IF Pack really is mutable.

declare
  Pack: Cards_Set := ...;  -- mutable object (no discriminant given in declaration)
begin
  PACK := (pack.nb-1, Pack.Set(pack.set'First..Pack.Nb-1));  -- this is OK, no Constraint_Error
end;

declare
  Pack: Cards_Set (52) := ...;  -- immutalbe object (discriminant given in declaration)
begin
  PACK := (pack.nb-1, Pack.Set(pack.set'First..Pack.Nb-1));  -- Constraint_Error (discriminant check)
end;