Re: derived formal types and known discriminants

[gautier_niouzes@hotmail.com]

"construction for an abstract parent type": just a wild guess: you would perhaps do something like this:

  type T is abstract tagged record
    i: Integer:= 1;
  end record;

  procedure Reset (x: in out T) is
    fresh_new: T;   --  GNAT: type of object cannot be abstract
  begin
    x:= fresh_new;  --  GNAT: target of assignment operation must not be abstract
  end;

...and you are blocked at the lines with comments.
Then a solution is a non-abstract grand-parent type:

  type Pre_T is tagged record
    i: Integer:= 1;
  end record;

  type T is abstract new Pre_T with null record;

  procedure Reset (x: in out T) is
    fresh_new: Pre_T;
  begin
    Pre_T(x):= fresh_new;
  end;

HTH...
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