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Subject: Re: Unchecked_Deallocation with tagged class type.
Date: Wed, 15 Nov 2023 21:26:06 +0100
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Le 14/11/2023 à 23:42, Dmitry A. Kazakov a écrit :
>> But what does "Finalize (OB);"?
> 
> Crashes your program. It is a bug. You should instantiate 
> Unchecked_Deallocation with class-wide type if you pass a class-wide 
> pointer.

Thanks, I haven't considered this possibility.
Note: the previous program built with GNAT FSF 13.2.0 ran without exception.

I've changed:
with Ada.Unchecked_Deallocation;
procedure test_20231113_free_class is

    type TTA is tagged record
       AA : Integer;
    end record;
    type ATTA is access all TTA;
    type CATTA is access all TTA'Class;
    procedure Finalize (O : in out CATTA) is
       procedure Free is new Ada.Unchecked_Deallocation (TTA'Class, CATTA);
    begin
       Free (O);
    end Finalize;

    type TTB is new TTA with record
       BB : Integer;
    end record;
    type ATTB is access all TTB;
    type CATTB is access all TTB'Class;
    procedure Finalize (O : in out CATTB) is
    begin
       Finalize (CATTA (O));
    end Finalize;

    OA : CATTA := new TTA;
    OB : CATTB := new TTB;

begin
    Finalize (OA);
    Finalize (OB);
end test_20231113_free_class;

It runs without exception.
One question remains about "Finalize (OB);":
Which memory size is deallocated TTA'Size or TTB'Size?

Thanks, Pascal.